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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Brass ACME nut repair
Now that I have my lathe "working", I started looking at its condition
a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#2
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Brass ACME nut repair
"Ignoramus22312" wrote in message
... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. Is it something you can take off, measure up and have someone make for you for less? If they did this, would you be guaranteed to have less slop? -- Regards, Joe Agro, Jr. (800) 871-5022 01.908.542.0244 Automatic / Pneumatic Drills: http://www.AutoDrill.com Multiple Spindle Drills: http://www.Multi-Drill.com V8013-R ** Posted from http://www.teranews.com ** |
#3
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Brass ACME nut repair
On 2008-07-14, Joe AutoDrill wrote:
"Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. Is it something you can take off, measure up and have someone make for you for less? If they did this, would you be guaranteed to have less slop? I can take off the part and mail it to whoever to replicate. I would obviously pay for it, but not anywhere close to $750, of course. I looked at the nut, it looks badly worn, I do not think that it was this way originally -- but, surely I would have to ascertain that again. I may be able to do something with my mill, original nut, and the McMaster nut. (as in, mill out the original nut, insert the mcMaster nut and braze in) -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#4
Posted to rec.crafts.metalworking
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Brass ACME nut repair
I can take off the part and mail it to whoever to replicate. I would
obviously pay for it, but not anywhere close to $750, of course. I looked at the nut, it looks badly worn, I do not think that it was this way originally -- but, surely I would have to ascertain that again. I may be able to do something with my mill, original nut, and the McMaster nut. (as in, mill out the original nut, insert the mcMaster nut and braze in) Ultimately, what could happen is that the McMaster is too loose or too tight and then you are almost back at square 1... But it's worth a try compared to $750! -- Regards, Joe Agro, Jr. (800) 871-5022 01.908.542.0244 Automatic / Pneumatic Drills: http://www.AutoDrill.com Multiple Spindle Drills: http://www.Multi-Drill.com V8013-R ** Posted from http://www.teranews.com ** |
#5
Posted to rec.crafts.metalworking
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Brass ACME nut repair
On 2008-07-14, Joe AutoDrill wrote:
I can take off the part and mail it to whoever to replicate. I would obviously pay for it, but not anywhere close to $750, of course. I looked at the nut, it looks badly worn, I do not think that it was this way originally -- but, surely I would have to ascertain that again. I may be able to do something with my mill, original nut, and the McMaster nut. (as in, mill out the original nut, insert the mcMaster nut and braze in) Ultimately, what could happen is that the McMaster is too loose or too tight and then you are almost back at square 1... But it's worth a try compared to $750! I think that I will buy one today. i -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#6
Posted to rec.crafts.metalworking
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Brass ACME nut repair
I can take off the part and mail it to whoever to replicate. I would
obviously pay for it, but not anywhere close to $750, of course. I looked at the nut, it looks badly worn, I do not think that it was this way originally -- but, surely I would have to ascertain that again. I may be able to do something with my mill, original nut, and the McMaster nut. (as in, mill out the original nut, insert the mcMaster nut and braze in) Ultimately, what could happen is that the McMaster is too loose or too tight and then you are almost back at square 1... But it's worth a try compared to $750! I think that I will buy one today. You can always return it if it doesn't fit the lead screw properly BEFORE modifying it. If you are going to braze it in, think about getting a piece of spare male thread to put in it to make sure it holds size during the process. Don't know if that will help or not in an overheat situation, but it's low cost insurance. Regards, Joe Agro, Jr. (800) 871-5022 01.908.542.0244 Automatic / Pneumatic Drills: http://www.AutoDrill.com Multiple Spindle Drills: http://www.Multi-Drill.com V8013-R ** Posted from http://www.teranews.com ** |
#7
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Brass ACME nut repair
On Mon, 14 Jul 2008 11:41:55 -0400, "Joe AutoDrill"
wrote: "Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. Is it something you can take off, measure up and have someone make for you for less? If they did this, would you be guaranteed to have less slop? I read posts like this frequently but in reality any machine tool built before the advent of ball screws had backlash in all its adjustments. Apprentices were taught to cope with this problem by making all adjustments in the same direction - opposite to the force being applied by the cutting tool. In your lathe's case, assuming normal turning operations, you back the tool off and then readjust it toward the work until you reach the dial setting you had used for the previous cut and then as much more as you want for the next cut. If you want less slop then just make a new nut.... after all, you've got the lathe to bore and thread the new nut. Bruce-in-Bangkok (correct Address is bpaige125atgmaildotcom) |
#8
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Brass ACME nut repair
On 2008-07-15, Bruce in Bangkok wrote:
On Mon, 14 Jul 2008 11:41:55 -0400, "Joe AutoDrill" wrote: "Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. Is it something you can take off, measure up and have someone make for you for less? If they did this, would you be guaranteed to have less slop? I read posts like this frequently but in reality any machine tool built before the advent of ball screws had backlash in all its adjustments. Apprentices were taught to cope with this problem by making all adjustments in the same direction - opposite to the force being applied by the cutting tool. You can adjust the cross slide in the opposite direction if you pull it by hand to "aid" it's motion. i In your lathe's case, assuming normal turning operations, you back the tool off and then readjust it toward the work until you reach the dial setting you had used for the previous cut and then as much more as you want for the next cut. If you want less slop then just make a new nut.... after all, you've got the lathe to bore and thread the new nut. Bruce-in-Bangkok (correct Address is bpaige125atgmaildotcom) -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#9
Posted to rec.crafts.metalworking
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Brass ACME nut repair
On 2008-07-15, Bruce in Bangkok wrote:
On Mon, 14 Jul 2008 11:41:55 -0400, "Joe AutoDrill" wrote: [ ... ] Is it something you can take off, measure up and have someone make for you for less? If they did this, would you be guaranteed to have less slop? I read posts like this frequently but in reality any machine tool built before the advent of ball screws had backlash in all its adjustments. Apprentices were taught to cope with this problem by making all adjustments in the same direction - opposite to the force being applied by the cutting tool. In your lathe's case, assuming normal turning operations, you back the tool off and then readjust it toward the work until you reach the dial setting you had used for the previous cut and then as much more as you want for the next cut. And -- one thing which you can do is to mount a dial indicator with a two or three inch travel so it measures the motion of the cross slide. This will be more accurate than a worn leadscrew in a worn nut. (If it were just the nut worn, you would have the same backlash all the way through the range, and your dials would be accurate enough. However, if the leadscrew is worn, that will be more so in the middle of the range, and will introduce extra errors -- unless you are measuring cross-slide travel with something which does not depend on the leadscrew. My 5418 had the leadscrew and nut so badly worn that it was producing 0.070" of backlash in the middle of travel -- and this on a 1/2" diameter leadscrew which produced a full 0.100" travel per rotation when in good shape. However -- the leadscrew and nut were a lot less expensive for mine -- at least back when I got it. :-) If you want less slop then just make a new nut.... after all, you've got the lathe to bore and thread the new nut. And at least you have a larger bore than I did. Beware that you will probably need to make a left-hand thread ACME, not just a normal ACME if your cross-slide is like mine. Check it out before you order anything. Good Luck, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
#10
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Brass ACME nut repair
On 16 Jul 2008 04:24:23 GMT, "DoN. Nichols"
wrote: And at least you have a larger bore than I did. Beware that you will probably need to make a left-hand thread ACME, not just a normal ACME if your cross-slide is like mine. Check it out before you order anything. Good Luck, DoN. If he's making nut and screw, he COULD use a RH thread - the cross-slide would just work backwards and take a bit of getting used to (and the scale would read backwards) ** Posted from http://www.teranews.com ** |
#11
Posted to rec.crafts.metalworking
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Brass ACME nut repair
"Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. You can also buy the appropriate acme tap and make a new nut. The nut part number you list above is for a right-hand nut. You might want to take a closer look at your old nut/screw---most I've seen are left-hand. Bill |
#12
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Brass ACME nut repair
On 2008-07-14, BillM wrote:
"Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. You can also buy the appropriate acme tap and make a new nut. $150 The nut part number you list above is for a right-hand nut. You might want to take a closer look at your old nut/screw---most I've seen are left-hand. Good point, I think that you are right. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#13
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Brass ACME nut repair
On Jul 14, 11:36*am, Ignoramus22312 ignoramus22...@NOSPAM.
22312.invalid wrote: Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. i deal with it by ignoring it. There's no climb-milling issue on a lathe. Look into Moglice |
#14
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Brass ACME nut repair
On 2008-07-14, Jim Wilkins wrote:
On Jul 14, 11:36*am, Ignoramus22312 ignoramus22...@NOSPAM. 22312.invalid wrote: Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. i deal with it by ignoring it. There's no climb-milling issue on a lathe. Look into Moglice What about facing? -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#15
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Brass ACME nut repair
On Jul 14, 2:06*pm, Ignoramus22312 ignoramus22...@NOSPAM.
22312.invalid wrote: On 2008-07-14, Jim Wilkins wrote: ... I deal with it by ignoring it. There's no climb-milling issue on a lathe. Look into Moglice What about facing? The free play on my lathe is 0.052" on the cross slide, 0.038" on the compound. The compound at 29 degrees would be more likely to slip forward and dig in if the tool had a large top rake, but I know better than to grind it that way. A top rake of 10 - 20 degree doesn't cause problems. I tried 60 degrees once after seeing it in an old book and did have trouble. |
#16
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Brass ACME nut repair
On Jul 14, 2:06*pm, Ignoramus22312 ignoramus22...@NOSPAM.
22312.invalid wrote: What about facing? -- What about facing? John Martin |
#17
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Brass ACME nut repair
On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312
wrote: Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. ========== All three appear to be viable alternatives, however be reminded that the screw may have worn in addition to the nut. If this is the case, although the total "slop" may be less, you can have a condition where the fit is tight at the ends and loose in the middle. I would try the "easy" fix (#2) first if the screw wear is not excessive, making sure that the epoxy sets up where the screw is "big" to avoid binding. Two brand names are Moglice and Turcite [Both manufacturers are very proud of their products and charge accordingly....] There may be cheaper generic or "knock off" products available. Any of our readers have some suggestions? http://www.moglice.com/ http://moglice.de/ http://www.mtsandtg.com/specialty/turcite http://www.paragonprecisionllc.com/?...FQEpIgod8id0TQ http://www.moglice-turcite.com/ It may be possible to disassemble and send the screw/nut to one of the machine rebuilders and have the moglice cast in place. An old time way to "fix" this was to open up the nut [ream the hole bigger, smoke the screw [to prevent adhesion], and pour babbitt. Lindsay Books has several good babbitt books if "old world craftsmanship" appeals. Books indicate this was a common half-nut repair at one time. http://lindsaybks.com/ http://lindsaybks.com/dgjp/djgbk/babbitt/index.html {scroll to bottom of page for 2 additional books} For some ideas [be setting down when you check prices] see http://www.techno-isel.com/Tic/acme_lead_screws.htm http://www.abssac.co.uk/Products/Spe...crew_nuts.html Good luck and let the group know how you make out, any problems, etc. Unka' George [George McDuffee] ------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end? Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625). |
#18
Posted to rec.crafts.metalworking
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Brass ACME nut repair
On 2008-07-14, F George McDuffee wrote:
On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312 wrote: Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. ========== All three appear to be viable alternatives, however be reminded that the screw may have worn in addition to the nut. If this is the case, although the total "slop" may be less, you can have a condition where the fit is tight at the ends and loose in the middle. I would try the "easy" fix (#2) first if the screw wear is not excessive, making sure that the epoxy sets up where the screw is "big" to avoid binding. Two brand names are Moglice and Turcite [Both manufacturers are very proud of their products and charge accordingly....] There may be cheaper generic or "knock off" products available. Any of our readers have some suggestions? http://www.moglice.com/ http://moglice.de/ http://www.mtsandtg.com/specialty/turcite http://www.paragonprecisionllc.com/?...FQEpIgod8id0TQ http://www.moglice-turcite.com/ It may be possible to disassemble and send the screw/nut to one of the machine rebuilders and have the moglice cast in place. An old time way to "fix" this was to open up the nut [ream the hole bigger, smoke the screw [to prevent adhesion], and pour babbitt. Lindsay Books has several good babbitt books if "old world craftsmanship" appeals. Books indicate this was a common half-nut repair at one time. http://lindsaybks.com/ http://lindsaybks.com/dgjp/djgbk/babbitt/index.html {scroll to bottom of page for 2 additional books} For some ideas [be setting down when you check prices] see http://www.techno-isel.com/Tic/acme_lead_screws.htm http://www.abssac.co.uk/Products/Spe...crew_nuts.html Good luck and let the group know how you make out, any problems, etc. I have ordered a nut from McMaster and will have it tomorrow. I will report my progress. The nut is big enough (3/4-5 ACME thread inside a 1 1/4" square) that I can attach another brass piece to it that would be attached to the cross slide. i Unka' George [George McDuffee] He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end? Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625). -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#19
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Brass ACME nut repair
On Mon, 14 Jul 2008 15:27:39 -0500, Ignoramus22312
wrote: I have ordered a nut from McMaster ====== also see http://www.roton.com/Sleeve_Nut.aspx?line=Acme It might be better to epoxy the nut in place as it will be easier to get back out if necessary..... also easier to shim into exact position. Setscrews might be good also. Unka' George [George McDuffee] ------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end? Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625). |
#20
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Brass ACME nut repair
On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312
wrote: Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. 4) Split the nut and make it adjustable. I've done this on two machines, a lathe and a surface grinder. On the lathe, the nut was rectangular and there was enough material around the thread to install two guide pins and two adjusting screws. Drill and ream for the guides before cutting the nut in two. The grinder's nut was cylindrical with a thin wall. I cut it in half and turned a fine male thread on each piece. A coupler with matching threads and the same OD as the nut allows for lash adjustment. None of these options will account for the inevitable unequal wear in the lead screw. -- Ned Simmons |
#21
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Brass ACME nut repair
On 2008-07-14, Ned Simmons wrote:
On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312 wrote: Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. 4) Split the nut and make it adjustable. I've done this on two machines, a lathe and a surface grinder. It is in such a bad shape, that doing so would not help. On the lathe, the nut was rectangular and there was enough material around the thread to install two guide pins and two adjusting screws. Drill and ream for the guides before cutting the nut in two. The grinder's nut was cylindrical with a thin wall. I cut it in half and turned a fine male thread on each piece. A coupler with matching threads and the same OD as the nut allows for lash adjustment. None of these options will account for the inevitable unequal wear in the lead screw. The lead screw is just $22 at McMaster-Carr, I will just buy it if I find a lot of wear on the existing one, but I expect (and saw) most of the wear on the brass nut. So I will start with the nut first. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#22
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Brass ACME nut repair
"Ignoramus22312" wrote in message ... On 2008-07-14, Ned Simmons wrote: On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312 wrote: Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. 4) Split the nut and make it adjustable. I've done this on two machines, a lathe and a surface grinder. It is in such a bad shape, that doing so would not help. On the lathe, the nut was rectangular and there was enough material around the thread to install two guide pins and two adjusting screws. Drill and ream for the guides before cutting the nut in two. The grinder's nut was cylindrical with a thin wall. I cut it in half and turned a fine male thread on each piece. A coupler with matching threads and the same OD as the nut allows for lash adjustment. None of these options will account for the inevitable unequal wear in the lead screw. The lead screw is just $22 at McMaster-Carr, I will just buy it if I find a lot of wear on the existing one, but I expect (and saw) most of the wear on the brass nut. So I will start with the nut first. I'm not positive, but suspect that the nuts and leadscrews sold by McMaster-Carr might be somewhat low precision. That might not be important for the compound or cross slide where travel is usually short, but you should be aware of it so you can make an informed decision. Mike |
#23
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Brass ACME nut repair
On 2008-07-15, Mike Henry wrote:
"Ignoramus22312" wrote in message ... On 2008-07-14, Ned Simmons wrote: On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312 wrote: Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. 4) Split the nut and make it adjustable. I've done this on two machines, a lathe and a surface grinder. It is in such a bad shape, that doing so would not help. On the lathe, the nut was rectangular and there was enough material around the thread to install two guide pins and two adjusting screws. Drill and ream for the guides before cutting the nut in two. The grinder's nut was cylindrical with a thin wall. I cut it in half and turned a fine male thread on each piece. A coupler with matching threads and the same OD as the nut allows for lash adjustment. None of these options will account for the inevitable unequal wear in the lead screw. The lead screw is just $22 at McMaster-Carr, I will just buy it if I find a lot of wear on the existing one, but I expect (and saw) most of the wear on the brass nut. So I will start with the nut first. I'm not positive, but suspect that the nuts and leadscrews sold by McMaster-Carr might be somewhat low precision. That might not be important for the compound or cross slide where travel is usually short, but you should be aware of it so you can make an informed decision. I think that all cross slides should have backlash, I just want to have it smaller. I think that I can do it without breaking anything and can always reuse the old nut. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#24
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Brass ACME nut repair
"Ignoramus19502" wrote in message ... On 2008-07-15, Mike Henry wrote: "Ignoramus22312" wrote in message ... On 2008-07-14, Ned Simmons wrote: On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312 wrote: Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. 4) Split the nut and make it adjustable. I've done this on two machines, a lathe and a surface grinder. It is in such a bad shape, that doing so would not help. On the lathe, the nut was rectangular and there was enough material around the thread to install two guide pins and two adjusting screws. Drill and ream for the guides before cutting the nut in two. The grinder's nut was cylindrical with a thin wall. I cut it in half and turned a fine male thread on each piece. A coupler with matching threads and the same OD as the nut allows for lash adjustment. None of these options will account for the inevitable unequal wear in the lead screw. The lead screw is just $22 at McMaster-Carr, I will just buy it if I find a lot of wear on the existing one, but I expect (and saw) most of the wear on the brass nut. So I will start with the nut first. I'm not positive, but suspect that the nuts and leadscrews sold by McMaster-Carr might be somewhat low precision. That might not be important for the compound or cross slide where travel is usually short, but you should be aware of it so you can make an informed decision. I think that all cross slides should have backlash, I just want to have it smaller. I think that I can do it without breaking anything and can always reuse the old nut. I was thinking more in terms of the error per unit of screw length, such as an error of 0.003"/inch of screw. That number is pulled out of thin air so is probably not typical and may not even be close to typical. And again, the issue is probably not a show stopper, just sonething you should be aware of. |
#25
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Brass ACME nut repair
First off, make sure everything is tight. 1/8 in is a boatload of slop for a
5 tpi nut. It mean your threads are only .075 thick at the base. It is a good chance that some of the slop is coming from the nut being loosely mounted or the handle on the screw not being mounted tight enough. If the lash drops down to something reasonable, learn to work around it and buy a new nut when one falls in your lap. If it is still that large, take a good look at the screw as well. McMaster carr sells a left hand bronze cylinder nut in 3/4-5 #95090A412 for 38 bucks. You could probably machine something up to fit. Paul K. Dickman "Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#26
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Brass ACME nut repair
On 2008-07-14, Paul K. Dickman wrote:
First off, make sure everything is tight. 1/8 in is a boatload of slop for a 5 tpi nut. It mean your threads are only .075 thick at the base. Yes. They are very thin. The whole brass nut looks like totally worn ****. (but the steel screw looks good, superficially). It is a good chance that some of the slop is coming from the nut being loosely mounted or the handle on the screw not being mounted tight enough. I wish. If the lash drops down to something reasonable, learn to work around it and buy a new nut when one falls in your lap. If it is still that large, take a good look at the screw as well. McMaster carr sells a left hand bronze cylinder nut in 3/4-5 #95090A412 for 38 bucks. You could probably machine something up to fit. I rather like item 95270A523, I think that it will be easier to adapt. (and cheaper too) i Paul K. Dickman "Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#27
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Brass ACME nut repair
On 2008-07-14, Ignoramus22312 wrote:
On 2008-07-14, Paul K. Dickman wrote: First off, make sure everything is tight. 1/8 in is a boatload of slop for a 5 tpi nut. It mean your threads are only .075 thick at the base. Yes. They are very thin. The whole brass nut looks like totally worn ****. (but the steel screw looks good, superficially). Check the width of the crest of the thread on the screw. Compare the crest in the middle and at the extreme ends to get an idea of how worn it is. (The accurate way to do this is with an optical comparator and with dial indicators on the slides.) As an example, the cross-slide leadscrew in my Clausing 5418 looked like this at the ends (as it should) (Of course -- view with a fixed pitch font like Courier -- I expect Iggy to do this normally, but others may not): _ _ _ _ _/ \_/ \_/ \_/ \_ But the middle looked like this: _/\__/\__/\__/\ _ The nut was worn too -- but not nearly as much as the leadscrew. Good Luck, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
#28
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Brass ACME nut repair
On 2008-07-16, DoN. Nichols wrote:
_/ \_/ \_/ \_/ \_ But the middle looked like this: _/\__/\__/\__/\ _ The nut was worn too -- but not nearly as much as the leadscrew. I have this too, but not much. I received the nut today and it does fit the leadscrew. I machined it today to be of yoke shape instead of square. I need to solder a little extra brass padding to complete the shape, and drill/tap that for the screw. I hope to have a replacement in a few days. I will not in any way disturb the original nut, so this is all quite safe. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#29
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Brass ACME nut repair
DoN. Nichols wrote:
... The nut was worn too -- but not nearly as much as the leadscrew. !!! That's not good - it would be much better to have to replace the nut than the lead screw. Or do you suppose that the nut had already been replaced, perhaps more than once? If not, do you suppose that the nut being softer had picked up steel dust & had acted as a lap on the screw? Is this normal? Bob |
#30
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Brass ACME nut repair
On 2008-07-16, Bob Engelhardt wrote:
DoN. Nichols wrote: ... The nut was worn too -- but not nearly as much as the leadscrew. !!! That's not good - it would be much better to have to replace the nut than the lead screw. Or do you suppose that the nut had already been replaced, perhaps more than once? I suspect the nut was replaced many times. This lathe came with a matching serial number bed turret and no tailstock, and I believe that the longitudinal feed was almost never used (the threading dial was in a drawer, and showed no signs of ever being mounted), and that all threading was done using Geometric die heads (or the like) in the turret. However -- the cross-feed was used for parting off work regularly, so I suspect that it had been through several nuts on that one leadscrew. Nobody cared that the dial was not accurate, because nothing was being turned to diameter with it. The precision turning was done with box tools in the turret, so they just tossed in a new nut (the cheapest part) to keep it working at the parting function. I had to chase down a tailstock for normal use, though I do use the turret for production runs of certain parts from time to time. If not, do you suppose that the nut being softer had picked up steel dust & had acted as a lap on the screw? The nut (being bronze not brass) is not *that* much softer than the mild steel of the leadscrew. I suspect that the lubing of the leadscrew and nut was ignored more than the rest of the lathe, because the lube point tends to get buried under chips. Is this normal? In a turret lathe used for production -- I think so. The next replacement would probably have needed a new leadscrew as well even for that function. But the compound leadscrew has very little wear or backlash, because that was ignored most of the time. Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
#31
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Brass ACME nut repair
On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312
wrote: Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. Here is how I did similar repair on 13: S.B. lathes. http://pages.cthome.net/errol.groff/...rew_repair.htm Errol Groff |
#32
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Brass ACME nut repair
On 2008-07-14, Errol Groff wrote:
On Mon, 14 Jul 2008 10:36:05 -0500, Ignoramus22312 wrote: Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. Here is how I did similar repair on 13: S.B. lathes. http://pages.cthome.net/errol.groff/...rew_repair.htm Errol Groff Very nice page Errol. I will see first if I can keep the screw, but if not, I will buy a screw also. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#33
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Brass ACME nut repair
Similar to an earlier suggestion, but slightly different: split the nut, so
it is like a pair of jam nuts, and then turn one half so the slop is taken out. Then, cross drill and pin, or silver solder, or come up with some other method of holding them. |
#34
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Brass ACME nut repair
thr split nut ideas are great if you have little wear and want to lessen the
slack, however, if you have more wear in one part of the screw than the other, this is likely to bind when you get out of this sweet spot... just a thought. "Leo Lichtman" wrote in message ... Similar to an earlier suggestion, but slightly different: split the nut, so it is like a pair of jam nuts, and then turn one half so the slop is taken out. Then, cross drill and pin, or silver solder, or come up with some other method of holding them. |
#35
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Brass ACME nut repair
Fixed an HF XY table with similar woes by compressing the nut in a BFP
in small increments until the lead screw had no lash. Worked well. JR Dweller in the cellar Ignoramus22312 wrote: Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. -- -------------------------------------------------------------- Home Page: http://www.seanet.com/~jasonrnorth If you're not the lead dog, the view never changes Doubt yourself, and the real world will eat you alive The world doesn't revolve around you, it revolves around me No skeletons in the closet; just decomposing corpses -------------------------------------------------------------- Dependence is Vulnerability: -------------------------------------------------------------- "Open the Pod Bay Doors please, Hal" "I'm sorry, Dave, I'm afraid I can't do that.." |
#36
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Brass ACME nut repair
I have been reading your threads and it is clear you have never rebuilt a
lathe. You will find that this is the tip of a big iceberg. You can do 2 things, rebuild it right, use it like it is, or sell it and buy one that isn't clapped out. So let's examine the first option. You don't have the tools to make your own parts, so you either have to buy the parts or pay some one else to make them. The advantage is you will know how to do this right the next time. You will spend a lot more money and time than you think and finally understand why it was sold for what you paid in the first place. The second option will teach you how to use a lathe. It will also teach you the tricks necessary to do accurate work with junk. (very valuable) Most importantly, sooner or later you will get a chance to use a good machine and then you will understand the difference first hand. After that, you will know why your machine was sold for the price you paid. The third choice is one you should make, but won't, until you experience either option 1 or option 2. Lastly, how do I know this? Because the brass nut is not brass. It is bronze. Probably Phosphor or Silicon Aluminum and much harder than brass. Please do not take offense to this reply. I am not trying to insult you. This is solid advice because many of us have been there and done this before, including me. I think this task is not only beyond your skill set, but you probably do not have access to a complete machine shop that this task will require. Furthermore, I really do not want to see you to waste the money option 1 will cost, because it isn't economically prudent. You are far better off spending the correct money for a good machine. Let me put option 1 in perspective. The last lathe I rebuilt was a 13 x 40, late model South Bend and it wasn't clapped out. It took me 18 months and $3,000 and I had all the tools I needed before hand. That cost did not include the purchase price. I did it because I liked the machine, not because it was the smart thing to do. Another thought you need to make is that the cost of the working machine typically represents about 50% of the total investment. The rest is the investment in tools and accessories. Often this last 50% can be even more. So I suggest you think about compatibility of tool cross use and the cost and general availability of the tool family, as this can vary widely as well. Steve "Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#37
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Brass ACME nut repair
On 2008-07-14, Steve Lusardi wrote:
I have been reading your threads and it is clear you have never rebuilt a lathe. yep You will find that this is the tip of a big iceberg. You can do 2 things, rebuild it right, use it like it is, or sell it and buy one that isn't clapped out. So let's examine the first option. You don't have the tools to make your own parts, so you either have to buy the parts or pay some one else to make them. The advantage is you will know how to do this right the next time. You will spend a lot more money and time than you think and finally understand why it was sold for what you paid in the first place. The second option will teach you how to use a lathe. It will also teach you the tricks necessary to do accurate work with junk. (very valuable) Most importantly, sooner or later you will get a chance to use a good machine and then you will understand the difference first hand. After that, you will know why your machine was sold for the price you paid. The third choice is one you should make, but won't, until you experience either option 1 or option 2. Lastly, how do I know this? Because the brass nut is not brass. It is bronze. Probably Phosphor or Silicon Aluminum and much harder than brass. Please do not take offense to this reply. I am not trying to insult you. This is solid advice because many of us have been there and done this before, including me. I think this task is not only beyond your skill set, but you probably do not have access to a complete machine shop that this task will require. Furthermore, I really do not want to see you to waste the money option 1 will cost, because it isn't economically prudent. You are far better off spending the correct money for a good machine. Let me put option 1 in perspective. The last lathe I rebuilt was a 13 x 40, late model South Bend and it wasn't clapped out. It took me 18 months and $3,000 and I had all the tools I needed before hand. That cost did not include the purchase price. I did it because I liked the machine, not because it was the smart thing to do. Another thought you need to make is that the cost of the working machine typically represents about 50% of the total investment. The rest is the investment in tools and accessories. Often this last 50% can be even more. So I suggest you think about compatibility of tool cross use and the cost and general availability of the tool family, as this can vary widely as well. Steve Steve, what did you have to fix with your lathe? As far as the machine shop goes, I have a mill, which is not much but it lets me do quite a few things that I need. Anyway, I think that you are right. And I had some experiences with DIY projects that ended up costing many times more than would be new brandname items, if I take the cost of my time into consideration. Anyhow, for now, my plan is to keep the lathe for a couple of months, learn how to use it a little bit, fix easy things (such as that on/off switch that I talked about, nut etc) and then I will sell it, properly described of course. i "Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#38
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Brass ACME nut repair
Smart boy! Good plan. I had two other lathes, a horizontal mill, 2 vertical
mills, 18" shaper, saws, and all the measurement tools including a precision level and a set of spindle calibration bars. On your lead screw nut issue, you must assume wear on both the nut and screw. Of course you will have more wear on the nut than the screw, but the point is that you will not eliminate all the back lash without introducing screw bind at the extremities of travel. Many times the follower nut is a split type with a wedge between the two halves. This will allow some backlash elimination by winding down the wedge. I do not know if this is true in your case. A bigger problem is of course the way wear. This will occur in the location of most use, eliminating the ability to correctly adjust the gib. This will manifest itself exactly in the same way as nut bind, so when setting up the nut, back off the gib to eliminate the confusion and optimize each, one at a time. Remember, you don't have to have everything perfect for the machine to be useful. You do have know how to tune it up though. Also on the same subject, many times the nut is not centered on the leadscrew in the vertical plane at the factory. Be prepared to remove the alignment pins, mill the mount surface of the nut or shim the nut as required. This entire operation can be further complicated if the lathe is equipped with a taper attachment, because the cross feed leadscrew in many cases is differential, forcing you to resolve any bind or looseness issues with that end first. Steve "Ignoramus22312" wrote in message ... On 2008-07-14, Steve Lusardi wrote: I have been reading your threads and it is clear you have never rebuilt a lathe. yep You will find that this is the tip of a big iceberg. You can do 2 things, rebuild it right, use it like it is, or sell it and buy one that isn't clapped out. So let's examine the first option. You don't have the tools to make your own parts, so you either have to buy the parts or pay some one else to make them. The advantage is you will know how to do this right the next time. You will spend a lot more money and time than you think and finally understand why it was sold for what you paid in the first place. The second option will teach you how to use a lathe. It will also teach you the tricks necessary to do accurate work with junk. (very valuable) Most importantly, sooner or later you will get a chance to use a good machine and then you will understand the difference first hand. After that, you will know why your machine was sold for the price you paid. The third choice is one you should make, but won't, until you experience either option 1 or option 2. Lastly, how do I know this? Because the brass nut is not brass. It is bronze. Probably Phosphor or Silicon Aluminum and much harder than brass. Please do not take offense to this reply. I am not trying to insult you. This is solid advice because many of us have been there and done this before, including me. I think this task is not only beyond your skill set, but you probably do not have access to a complete machine shop that this task will require. Furthermore, I really do not want to see you to waste the money option 1 will cost, because it isn't economically prudent. You are far better off spending the correct money for a good machine. Let me put option 1 in perspective. The last lathe I rebuilt was a 13 x 40, late model South Bend and it wasn't clapped out. It took me 18 months and $3,000 and I had all the tools I needed before hand. That cost did not include the purchase price. I did it because I liked the machine, not because it was the smart thing to do. Another thought you need to make is that the cost of the working machine typically represents about 50% of the total investment. The rest is the investment in tools and accessories. Often this last 50% can be even more. So I suggest you think about compatibility of tool cross use and the cost and general availability of the tool family, as this can vary widely as well. Steve Steve, what did you have to fix with your lathe? As far as the machine shop goes, I have a mill, which is not much but it lets me do quite a few things that I need. Anyway, I think that you are right. And I had some experiences with DIY projects that ended up costing many times more than would be new brandname items, if I take the cost of my time into consideration. Anyhow, for now, my plan is to keep the lathe for a couple of months, learn how to use it a little bit, fix easy things (such as that on/off switch that I talked about, nut etc) and then I will sell it, properly described of course. i "Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
#39
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Brass ACME nut repair
Steve, can you share, what did you have to do to fix up your lathe?
I do not want to eliminate all backlash, just some. The screw has wear, but not much. I will post some numbers on the backlash prior and after the replacement. i On 2008-07-15, Steve Lusardi wrote: Smart boy! Good plan. I had two other lathes, a horizontal mill, 2 vertical mills, 18" shaper, saws, and all the measurement tools including a precision level and a set of spindle calibration bars. On your lead screw nut issue, you must assume wear on both the nut and screw. Of course you will have more wear on the nut than the screw, but the point is that you will not eliminate all the back lash without introducing screw bind at the extremities of travel. Many times the follower nut is a split type with a wedge between the two halves. This will allow some backlash elimination by winding down the wedge. I do not know if this is true in your case. A bigger problem is of course the way wear. This will occur in the location of most use, eliminating the ability to correctly adjust the gib. This will manifest itself exactly in the same way as nut bind, so when setting up the nut, back off the gib to eliminate the confusion and optimize each, one at a time. Remember, you don't have to have everything perfect for the machine to be useful. You do have know how to tune it up though. Also on the same subject, many times the nut is not centered on the leadscrew in the vertical plane at the factory. Be prepared to remove the alignment pins, mill the mount surface of the nut or shim the nut as required. This entire operation can be further complicated if the lathe is equipped with a taper attachment, because the cross feed leadscrew in many cases is differential, forcing you to resolve any bind or looseness issues with that end first. Steve "Ignoramus22312" wrote in message ... On 2008-07-14, Steve Lusardi wrote: I have been reading your threads and it is clear you have never rebuilt a lathe. yep You will find that this is the tip of a big iceberg. You can do 2 things, rebuild it right, use it like it is, or sell it and buy one that isn't clapped out. So let's examine the first option. You don't have the tools to make your own parts, so you either have to buy the parts or pay some one else to make them. The advantage is you will know how to do this right the next time. You will spend a lot more money and time than you think and finally understand why it was sold for what you paid in the first place. The second option will teach you how to use a lathe. It will also teach you the tricks necessary to do accurate work with junk. (very valuable) Most importantly, sooner or later you will get a chance to use a good machine and then you will understand the difference first hand. After that, you will know why your machine was sold for the price you paid. The third choice is one you should make, but won't, until you experience either option 1 or option 2. Lastly, how do I know this? Because the brass nut is not brass. It is bronze. Probably Phosphor or Silicon Aluminum and much harder than brass. Please do not take offense to this reply. I am not trying to insult you. This is solid advice because many of us have been there and done this before, including me. I think this task is not only beyond your skill set, but you probably do not have access to a complete machine shop that this task will require. Furthermore, I really do not want to see you to waste the money option 1 will cost, because it isn't economically prudent. You are far better off spending the correct money for a good machine. Let me put option 1 in perspective. The last lathe I rebuilt was a 13 x 40, late model South Bend and it wasn't clapped out. It took me 18 months and $3,000 and I had all the tools I needed before hand. That cost did not include the purchase price. I did it because I liked the machine, not because it was the smart thing to do. Another thought you need to make is that the cost of the working machine typically represents about 50% of the total investment. The rest is the investment in tools and accessories. Often this last 50% can be even more. So I suggest you think about compatibility of tool cross use and the cost and general availability of the tool family, as this can vary widely as well. Steve Steve, what did you have to fix with your lathe? As far as the machine shop goes, I have a mill, which is not much but it lets me do quite a few things that I need. Anyway, I think that you are right. And I had some experiences with DIY projects that ended up costing many times more than would be new brandname items, if I take the cost of my time into consideration. Anyhow, for now, my plan is to keep the lathe for a couple of months, learn how to use it a little bit, fix easy things (such as that on/off switch that I talked about, nut etc) and then I will sell it, properly described of course. i "Ignoramus22312" wrote in message ... Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. -- Due to extreme spam originating from Google Groups, and their inattention to spammers, I and many others block all articles originating from Google Groups. If you want your postings to be seen by more readers you will need to find a different means of posting on Usenet. http://improve-usenet.org/ |
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Brass ACME nut repair
Ignoramus22312 wrote: Now that I have my lathe "working", I started looking at its condition a little more closely. On my lathe, the cross slide is moved by a 3/4-5 ACME screw, that moves a brass nut attached to the cross slide. There is a lot of wear in this, as in, maybe 1/16 to 1/8" of slop. I was thinking about fixing this. Three things come to mind. 1) Buy a McMaster ACME brass nut 95270A123 and attach it to a custom made part to fit under the cross slide. 2) Do something clever like wax the screw and inject epoxy into the nut to take up the slop. 3) Make a replacement part on the mill and lathe. Has anyone dealt with this issue. Clausing wants $750 (not a typo) to custom make this part for me. First, measure the thickness of the thread land of the LEADSCREW at the ends of travel and the middle. If it is much thinner in the middle, all of the above plans will end up binding when away from the center of travel. But, you have a workable lathe! You can cut a new screw and a new nut. Make the screw first, as it is pretty easy to do. Then, you can cut the nut, and test-fit with the screw until it is a snug but working fit. Remember that the cross slide is a LEFT HAND thread! Don't ASK why I know this so well! If the screw actually turns out to be fine (unlikely) you can just make a new nut. But, note that a screw with differential wear is not very accurate to move from here to there, so if it is worn, and you don't have a DRO, you really want to take the opportunity to replace/remake it. Jon |
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