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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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Half nuts disengage by themselves
The cleanup of the lathe is basically done all around, the VFD is
wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this. i |
#2
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Half nuts disengage by themselves
In article ,
Ignoramus25542 wrote: The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this? Wear and/or maladjustment. How much backlash does the closed half-nut have? (This ordinarily does not matter unless one is making very accurate and long screw threads, but is used to gauge wear.) Joe Gwinn |
#3
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Half nuts disengage by themselves
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#5
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Half nuts disengage by themselves
On Feb 4, 8:11*am, Ignoramus25542 ignoramus25...@NOSPAM.
25542.invalid wrote: The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this. i First things first. Have you ever cleaned them? I've seen half nuts pack up with swarf and gummy oil so much that they would not engage fully. A good cleaning may make them almost as good as new. Or not. John Martin |
#6
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Half nuts disengage by themselves
On 2010-02-04, Joseph Gwinn wrote:
In article , Ignoramus25542 wrote: The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this? Wear and/or maladjustment. How much backlash does the closed half-nut have? (This ordinarily does not matter unless one is making very accurate and long screw threads, but is used to gauge wear.) Joe... Thanks... I called Clausing and talked to Tito. He told me to first clean the leadscrew very well and check the wear on slots of the round slotted circle that closes half nuts. This leadscrew proved exceptionally difficult to clean, in fact, I may just take it off and use a powerwasher or take it to a hot shower. I spent a lot of time cleaning it and it is still not as clean as it should be. The half nuts are $100 from Clausing, so even if they are bad, it is not the end of the world. i |
#7
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Half nuts disengage by themselves
On 2010-02-04, Ed Huntress wrote:
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message .70... Joseph Gwinn fired this volley in news:joegwinn- : In article , Ignoramus25542 wrote: ... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this? Wear and/or maladjustment. How much backlash does the closed half-nut have? (This ordinarily does not matter unless one is making very accurate and long screw threads, but is used to gauge wear.) Joe Gwinn Iggy, odds are you'll find almost no thread at all in the half-nuts. As they become severely worn, the will tend to "hop" out of engagement. There's only one solution -- replace them; if you're really in a pinch, you can re-make the parts, but I'd look for replacements first. LLoyd And one additional point: If it does come down to making the replacements, and you have to make them on the same lathe, MAKE THEM NOW! Once the half-nuts won't hold engagement at all, you're screwed. A few points of note. 1) New half nuts are $100 from Clausing (and I think they include a new slotted circle for engaging them) 2) I have an extra pair of worn half nuts that came with the lathe 3) I think that you guys are right, I will try to take off the carriage and apron and look at half nuts. Taking that stuff off will be beneficial in other ways, such as cleaning the sliding surface, etc. |
#8
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Half nuts disengage by themselves
"Ignoramus25542" wrote in message ... On 2010-02-04, Joseph Gwinn wrote: In article , Ignoramus25542 wrote: The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this? Wear and/or maladjustment. How much backlash does the closed half-nut have? (This ordinarily does not matter unless one is making very accurate and long screw threads, but is used to gauge wear.) Joe... Thanks... I called Clausing and talked to Tito. He told me to first clean the leadscrew very well and check the wear on slots of the round slotted circle that closes half nuts. This leadscrew proved exceptionally difficult to clean, in fact, I may just take it off and use a powerwasher or take it to a hot shower. I spent a lot of time cleaning it and it is still not as clean as it should be. If you have the lathe running, set it to a slow speed/feedrate and wrap a piece of heavy cotton cord ONCE ONLY around a groove in the leadscrew at one end; pull hard on the cord; traverse the cord to the other end. Soaking it in paint thinner, or, in a pinch, WD-40, will help clean out a lot of gunk. The half nuts are $100 from Clausing, so even if they are bad, it is not the end of the world. i |
#9
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Half nuts disengage by themselves
"Ignoramus25542" wrote in message ... On 2010-02-04, Ed Huntress wrote: "Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message .70... Joseph Gwinn fired this volley in news:joegwinn- : In article , Ignoramus25542 wrote: ... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this? Wear and/or maladjustment. How much backlash does the closed half-nut have? (This ordinarily does not matter unless one is making very accurate and long screw threads, but is used to gauge wear.) Joe Gwinn Iggy, odds are you'll find almost no thread at all in the half-nuts. As they become severely worn, the will tend to "hop" out of engagement. There's only one solution -- replace them; if you're really in a pinch, you can re-make the parts, but I'd look for replacements first. LLoyd And one additional point: If it does come down to making the replacements, and you have to make them on the same lathe, MAKE THEM NOW! Once the half-nuts won't hold engagement at all, you're screwed. A few points of note. 1) New half nuts are $100 from Clausing (and I think they include a new slotted circle for engaging them) 2) I have an extra pair of worn half nuts that came with the lathe 3) I think that you guys are right, I will try to take off the carriage and apron and look at half nuts. Taking that stuff off will be beneficial in other ways, such as cleaning the sliding surface, etc. And look for settled gunk in the apron. -- Ed Huntress |
#10
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Half nuts disengage by themselves
On 2010-02-04, Ed Huntress wrote:
And look for settled gunk in the apron. Regarding taking off apron: I did try this once. It did not work: the "carriage locking screw" would not unscrew all the way. I did not want to force it and I had other issues, so I gave up and moved on to other things, but now is the time to look at it. The carriage locking screw connects to a plate under the carriage, so that when you tighten it it grabs the bed. The screw unscrews, but stops midway and I wanted to know if I am doing something wrong or should just use a bit more force. i |
#11
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Half nuts disengage by themselves
"Ignoramus25542" wrote in message ... On 2010-02-04, Ed Huntress wrote: And look for settled gunk in the apron. Regarding taking off apron: I did try this once. It did not work: the "carriage locking screw" would not unscrew all the way. I did not want to force it and I had other issues, so I gave up and moved on to other things, but now is the time to look at it. The carriage locking screw connects to a plate under the carriage, so that when you tighten it it grabs the bed. The screw unscrews, but stops midway and I wanted to know if I am doing something wrong or should just use a bit more force. i Good question. I hope someone who knows your lathe can give you an answer, because it would be a bugger to strip a special screw trying to find out. -- Ed Huntress |
#12
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Half nuts disengage by themselves
On Feb 4, 11:29*am, "Ed Huntress" wrote:
"Ignoramus25542" wrote in message ... On 2010-02-04, Joseph Gwinn wrote: In article , *Ignoramus25542 wrote: The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this? Wear and/or maladjustment. *How much backlash does the closed half-nut have? *(This ordinarily does not matter unless one is making very accurate and long screw threads, but is used to gauge wear.) Joe... Thanks... I called Clausing and talked to Tito. He told me to first clean the leadscrew very well and check the wear on slots of the round slotted circle that closes half nuts. This leadscrew proved exceptionally difficult to clean, in fact, I may just take it off and use a powerwasher or take it to a hot shower. I spent a lot of time cleaning it and it is still not as clean as it should be. If you have the lathe running, set it to a slow speed/feedrate and wrap a piece of heavy cotton cord ONCE ONLY around a groove in the leadscrew at one end; pull hard on the cord; traverse the cord to the other end. Soaking it in paint thinner, or, in a pinch, WD-40, will help clean out a lot of gunk. The half nuts are $100 from Clausing, so even if they are bad, it is not the end of the world. i AND DON"T WRAP THE CORD AROUND EITHER HAND!! Attaching the cord ends to the end of a board and holding the board would add a safety factor, and let you pull harder. Dave |
#13
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Half nuts disengage by themselves
John Martin wrote:
On Feb 4, 8:11 am, Ignoramus25542 ignoramus25...@NOSPAM. 25542.invalid wrote: The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this. i First things first. Have you ever cleaned them? I've seen half nuts pack up with swarf and gummy oil so much that they would not engage fully. A good cleaning may make them almost as good as new. Or not. John Martin The half nuts on my Wards/Logan were gunked like that . Crud between the halves blocked them closing all the way . Makes 'em wear faster too . -- Snag New ones for mine were about the same price . |
#14
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Half nuts disengage by themselves
Ignoramus25542 wrote:
If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this. If your half nuts are in good shape, crap/chips embedded in the half nuts. Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller |
#15
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Half nuts disengage by themselves
"Ed Huntress" wrote:
If you have the lathe running, set it to a slow speed/feedrate and wrap a piece of heavy cotton cord ONCE ONLY around a groove in the leadscrew at one end; pull hard on the cord; traverse the cord to the other end. Soaking it in paint thinner, or, in a pinch, WD-40, will help clean out a lot of gunk. That is an excellent suggestion! Btw, if you haven't seen his model of lathe, it has a rather fine pitched lead screw so a bit of dirt is a lot of dirt. Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller |
#16
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Half nuts disengage by themselves
"Wes" wrote in message ... "Ed Huntress" wrote: If you have the lathe running, set it to a slow speed/feedrate and wrap a piece of heavy cotton cord ONCE ONLY around a groove in the leadscrew at one end; pull hard on the cord; traverse the cord to the other end. Soaking it in paint thinner, or, in a pinch, WD-40, will help clean out a lot of gunk. That is an excellent suggestion! An old, old trick. g Btw, if you haven't seen his model of lathe, it has a rather fine pitched lead screw so a bit of dirt is a lot of dirt. Wes I don't remember it, but that would make it even more suitable. That's how I clean the screw on my SB. -- Ed Huntress |
#17
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Half nuts disengage by themselves
"Ed Huntress" wrote:
That is an excellent suggestion! An old, old trick. g I know, and I've heard it before but the other day when I looked at my screw that is the same only other then shorter, I couldn't remember that trick for cleaning. I guess you win the been around long enough to know that one award. No monetary value. Btw, if you haven't seen his model of lathe, it has a rather fine pitched lead screw so a bit of dirt is a lot of dirt. I don't remember it, but that would make it even more suitable. That's how I clean the screw on my SB. That is going to be my way on my lathe also. Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller |
#18
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Half nuts disengage by themselves
Ignoramus25542 wrote:
The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this. Classic case of worn half-nuts. But, take the whole mechanism apart, there may have been a detent mechanism that has gotten gummed up or worn. If not that, then it is likely due to wear of the half-nut threads that are now pushing the nuts apart. It could also be a misalignment of the nuts to the leadscrew, swarf packed into the half nuts preventing them from fully closing or something like that. Jon |
#19
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Half nuts disengage by themselves
Ignoramus25542 wrote:
On 2010-02-04, Ed Huntress wrote: And look for settled gunk in the apron. Regarding taking off apron: I did try this once. It did not work: the "carriage locking screw" would not unscrew all the way. I did not want to force it and I had other issues, so I gave up and moved on to other things, but now is the time to look at it. The carriage locking screw connects to a plate under the carriage, so that when you tighten it it grabs the bed. The screw unscrews, but stops midway and I wanted to know if I am doing something wrong or should just use a bit more force. Geez, I'm not sure. Is this a classic Atlas, or a Clausing industrial lathe? I know the Atlas pretty well, I'm the moderator of the Atlas-Craftsman group on Yahoo. I wouldn't be too surprised if there is something to prevent the clamp plate from completely unscrewing and falling into the half-nut mechanism. I don't think the Atlas had such a protection. Anyway, you should be able to run the carriage at least partly off the right end of the bed to examine the parts. Take the tailstock off and then remove the right-end leadscrew bracket. Jon |
#20
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Half nuts disengage by themselves
Ignoramus25542 wrote:
This leadscrew proved exceptionally difficult to clean, in fact, I may just take it off and use a powerwasher or take it to a hot shower. I spent a lot of time cleaning it and it is still not as clean as it should be. One trick is to grind a small screwdriver or similar piece to match the thread, and then run the lathe at low speed and hold the tool in the groove. A keyed Acme screw is a little harder to clean this way, but it definitely works. If swarf is packed totally hard in the screw, water won't get it out, anyway, and that is likely part of the threading trouble. If the screw is packed with rammed-in chips, the nuts will be worse! Jon |
#21
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Half nuts disengage by themselves
Ed Huntress wrote:
Btw, if you haven't seen his model of lathe, it has a rather fine pitched lead screw so a bit of dirt is a lot of dirt. Hmm? It would almost have to be either 8 or 16 TPI for Imperial thread pitches. Jon |
#22
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Half nuts disengage by themselves
On 2010-02-04, Ignoramus25542 wrote:
The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this. I can think a few possible causes: 1) A large chip embedded in the Acme thread of the leadscrew (or the long key groove used to power the power feed in some machines). 2) A bent leadscrew, bumping the half-nuts open. 3) Badly worn half-nut threads. (It is possible to cast new ones in Babbit metal.) 4) Missing detent spring in the half-nuts lever assembly. 5) Is the interlock between the half-nut lever and the power feed lever working properly? It should not be possible to engage both at the same time. Each should lock out the other. 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 --- |
#23
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Half nuts disengage by themselves
On Feb 4, 7:39*pm, "DoN. Nichols" wrote:
On 2010-02-04, Ignoramus25542 wrote: The cleanup of the lathe is basically done all around, the VFD is wired the way I want and things are cookin'. Got something else going on... If I try threading, the half nuts would not stay engaged, they lose this engamenent in a second or so. If I hold the engagement lever, they they do stay engaged, but I feel the lever kind of bumping. What would be the typical cause of this. * * * * I can think a few possible causes: 1) * * *A large chip embedded in the Acme thread of the leadscrew (or * * * * the long key groove used to power the power feed in some * * * * machines). 2) * * *A bent leadscrew, bumping the half-nuts open. 3) * * *Badly worn half-nut threads. *(It is possible to * * * * cast new ones in Babbit metal.) 4) * * *Missing detent spring in the half-nuts lever assembly. 5) * * *Is the interlock between the half-nut lever and the power * * * * feed lever working properly? *It should not be possible to * * * * engage both at the same time. *Each should lock out the other. * * * * 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 --- I found that a tooth brush is pretty good for cleaning the lead screw. Just hold it against the screw at an angle. If the crap is packed really tight in the (fine) threads a brass brush would be better. Don't think I'd use a steel implement to run in the threads. My olde 6" Atlas would develop a similar symptom and it turned out to be crap collected in the threads thereof. A good cleaning and oiling and we were good to go. As Jon wrote above, On this lathe the whole carriage can be removed by sliding it off the right hand end off the bed. Only had to remove the lead screw bearing to to this. Wolfgang |
#24
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Half nuts disengage by themselves
"Jon Elson" wrote in message ... Ignoramus25542 wrote: On 2010-02-04, Ed Huntress wrote: And look for settled gunk in the apron. Regarding taking off apron: I did try this once. It did not work: the "carriage locking screw" would not unscrew all the way. I did not want to force it and I had other issues, so I gave up and moved on to other things, but now is the time to look at it. The carriage locking screw connects to a plate under the carriage, so that when you tighten it it grabs the bed. The screw unscrews, but stops midway and I wanted to know if I am doing something wrong or should just use a bit more force. Geez, I'm not sure. Is this a classic Atlas, or a Clausing industrial lathe? I know the Atlas pretty well, I'm the moderator of the Atlas-Craftsman group on Yahoo. I wouldn't be too surprised if there is something to prevent the clamp plate from completely unscrewing and falling into the half-nut mechanism. I don't think the Atlas had such a protection. Anyway, you should be able to run the carriage at least partly off the right end of the bed to examine the parts. Take the tailstock off and then remove the right-end leadscrew bracket. Jon My Atlas 1/2nuts always are disconnecting from the drive screw. What should I look at there? |
#25
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Half nuts disengage by themselves
In article ,
Ignoramus25542 wrote: On 2010-02-04, Ed Huntress wrote: And look for settled gunk in the apron. Regarding taking off apron: I did try this once. It did not work: the "carriage locking screw" would not unscrew all the way. I did not want to force it and I had other issues, so I gave up and moved on to other things, but now is the time to look at it. The carriage locking screw connects to a plate under the carriage, so that when you tighten it it grabs the bed. The screw unscrews, but stops midway and I wanted to know if I am doing something wrong or should just use a bit more force. I took mine apart and cleaned it without difficulty. It was very dirty. The carriage clamp bolt just unscrewed, so I bet that you are being blocked by some spooge on the ordinarily unused part of the bolt thread. Do not try to force it, at least not initially. Instead, use a scriber or pick to break the deposits up first. Soaking with acetone also helps a lot, as does ordinary methylene chloride based paint stripper. Once the bulk deposits are removed, a little force is OK - the parts are all made of steel. I just looked at the manuals for 5900 and 6900 series lathes. The carriage clamps are identical, as shown on page 31 (pdf page 38) of the 6900 series manual. It's just a bolt screwing into a block. Joe Gwinn |
#26
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Half nuts disengage by themselves
Bill McKee wrote:
My Atlas 1/2nuts always are disconnecting from the drive screw. What should I look at there? First, clean the screw and nuts and associated mechanism. You may need an awl or something to pick the most stubborn bits of swarf out of the teeth. If the half nuts or the cam that engages them are badly worn, there may not be much you can do to help them. If you have a 3/4" leadscrew, replacement parts are available from the Clausing Service Center for what seems a reasonable price. If the leadscrew is bent, it need to be straightened. Also check that the leadscrew is running through the center line of the nuts. if the bed has been ground or something it might be off-center. My recollection is now hazy, but I seem to recall a detent ball and spring that helps retain the cam and engagement handle in position. So you can check the condition of that. If the teeth of the nuts are worn very much, they form a ramp that drives the nuts apart. Also, a really badly worn leadscrew can get the same way. The only hope there is replacement. Jon |
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