Questions about shop made threading dial
I am going to make a threading dial for my Jet 1024. It seems pretty
straight forward, but I want to do a sanity check and ask a couple of questions. 1. My Logan 200 and the Jet have the same lead screw (8 tpi). I assume that this means I should use a 16 tooth dial gear, as that is what the Logan has. 2. The lead screw looks like an Acme thread, could it be something else? If so, how would I figure out what it is? 3. What is this kind of gear called? I.e., when I call Boston Gear, what should I say I need? Is "To fit an 8 tpi Acme thread sufficient"? Thanks, Bob |
In article ,
Bob Engelhardt wrote: I am going to make a threading dial for my Jet 1024. It seems pretty straight forward, but I want to do a sanity check and ask a couple of questions. 1. My Logan 200 and the Jet have the same lead screw (8 tpi). I assume that this means I should use a 16 tooth dial gear, as that is what the Logan has. 2. The lead screw looks like an Acme thread, could it be something else? If so, how would I figure out what it is? 3. What is this kind of gear called? I.e., when I call Boston Gear, what should I say I need? Is "To fit an 8 tpi Acme thread sufficient"? Since there is no load on the teeth, tooth form is not important. -- Free men own guns, slaves don't www.geocities.com/CapitolHill/5357/ |
I agree with Nick. The form is not important. But I am pretty sure
that the form for mating with a Acme thread is a 14.5 pressure angle. Dan Nick Hull wrote: Since there is no load on the teeth, tooth form is not important. -- Free men own guns, slaves don't www.geocities.com/CapitolHill/5357/ |
In article ,
says... 3. What is this kind of gear called? I.e., when I call Boston Gear, what should I say I need? Is "To fit an 8 tpi Acme thread sufficient"? Ignoring the tooth form, which Nick has responded to, you won't be able to buy a stock gear of the proper pitch. If I did the math right, you'd need a 25.133 diametral pitch gear (8 x pi), or a 1.01 Module (metric) gear. Huh, maybe you could get away with a 1.0 Module. I don't think McMaster carries Module gears, you can get them from Ametric if you're willing to give it a try. http://www.ametric.com/home.htm Since the tooth form will be wrong, you might consider a design that would allow disengaging the thread dial when it's not being used, especially if this is a lathe that doesn't have a separate shaft for the regular feeds, i.e., the lead screw is always turning. Ned Simmons |
On Sun, 07 Aug 2005 15:31:37 -0400, Bob Engelhardt
wrote: I am going to make a threading dial for my Jet 1024. It seems pretty straight forward, but I want to do a sanity check and ask a couple of questions. 1. My Logan 200 and the Jet have the same lead screw (8 tpi). I assume that this means I should use a 16 tooth dial gear, as that is what the Logan has. 2. The lead screw looks like an Acme thread, could it be something else? If so, how would I figure out what it is? 3. What is this kind of gear called? I.e., when I call Boston Gear, what should I say I need? Is "To fit an 8 tpi Acme thread sufficient"? Thanks, Bob Hi Bob, I'm not sure if this helps or not, but the threading dial I use on my 1024 (the twin of yours...) is from a 9" South Bend, same 8TPI lead screw, but the gear on the threading dial is 32 teeth. I stumbled on the SB indicator and having nothing to lose, just tried it on my Jet, which did not have one when I got it. Nice smooth operation with minimal slop. Works fine. I am pretty sure that someone else here can tell you what sort of thread form a SB uses. Should be close enough. -AL A. PS, how did you make out with the backgears? Did you get that all straightened out? -AL |
Nick Hull wrote:
Since there is no load on the teeth, tooth form is not important. Good point. That will make one easier to find. Except ... Ned Simmons wrote: Ignoring the tooth form, which Nick has responded to, you won't be able to buy a stock gear of the proper pitch. Oh, no! That means I'll *have* to buy a dividing head (to make my own gear on the mill). I'm sure that my wife will understand. VBG If I did the math right, you'd need a 25.133 diametral pitch gear (8 x pi)... IIRC, the formula: (# teeth + 2) / OD gives the DP. In this case: (16+2)/.715 = 25.17. Pretty close - it has to be an approximation, that "teeth + 2" is just too simple to be dead on. Since the tooth form will be wrong, you might consider a design that would allow disengaging the thread dial when it's not being used, especially if this is a lathe that doesn't have a separate shaft for the regular feeds, i.e., the lead screw is always turning. I'm just using the basic design from the Logan (a pivoting assembly), which allows disengagement. But the Jet does have a separate lead screw, so I'm covered twice. Thanks for the replies, Bob |
There is an article on making said gear with a lathe on a the yahoo SB10k group. Its a jpg file if you want it email me (despam my address), also one of HSM magazines had a recent article on hobbing a threading dial gear. Looks like a interesting project, I made a thread dial but bought the gear. DE Hi Bob, I'm not sure if this helps or not, but the threading dial I use on my 1024 (the twin of yours...) is from a 9" South Bend, same 8TPI lead screw, but the gear on the threading dial is 32 teeth. I stumbled on the SB indicator and having nothing to lose, just tried it on my Jet, which did not have one when I got it. Nice smooth operation with minimal slop. Works fine. I am pretty sure that someone else here can tell you what sort of thread form a SB uses. Should be close enough. -AL A. PS, how did you make out with the backgears? Did you get that all straightened out? -AL ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
I am going to make a threading dial for my Jet 1024. It seems pretty
straight forward, but I want to do a sanity check and ask a couple of questions. 1. My Logan 200 and the Jet have the same lead screw (8 tpi). I assume that this means I should use a 16 tooth dial gear, as that is what the Logan has. 2. The lead screw looks like an Acme thread, could it be something else? If so, how would I figure out what it is? 3. What is this kind of gear called? I.e., when I call Boston Gear, what should I say I need? Is "To fit an 8 tpi Acme thread sufficient"? Thanks, Bob check this out.... ebay item #7536944404 I have an Craftsman/Atlas 12x36 with 8TPI leadscrew and this one is the same as mine. Will probably work on yours. Bolts to the apron, loosen mounting screw and the unit swivels away from the lead screw to disengage. HTH Ken. |
Al A. wrote:
... the threading dial I use on my 1024 (the twin of yours...) is from a 9" South Bend, same 8TPI lead screw, but the gear on the threading dial is 32 teeth. ... Your dial is rotating at half the speed (relative to the lead screw) as a 16 tooth dial. Does that mean that your dial has twice as many marks? There are 4 marks on my Logan dial: "1" & "2" 180 degrees apart and a "|" between them. PS, how did you make out with the backgears? Did you get that all straightened out? The bushings on the spindle pulley were badly scored, so I replaced them. Of course, they were not a standard size, so I had to turn them to fit (Catch 22 - I needed a lathe to fix my lathe). Boring them out wasn't a big deal, but one of them had a *taper* on the OD! Re-assembling it was a lot easier after boring out the bull gear a smidgen. After it was all assembled and I added oil to the reservoirs I discovered that the inboard seal on the outboard bearing was bad (leaked). It would have been easy to replace, but I'm not going to take it apart again just for that seal. I'll just keep adding oil. Bob |
Response top posted:
Hi Bob :) If you can get your hands on a copy of the Home Shop Machinist, May/June 2000, page 38, Peter Lott has a four page article called " the Lathe Thread-Chasing Dial- - - Lathes with Inch-Thread Screws". He goes into the whys, hows and wherefores of the threading dials and how he made one for his 12" Seneca Falls Star lathe. Lots of good info including how he calculated the drive gear. Also a 'Thread Chasing Dial Table' for use with even and odd thread lead screws. Best of luck Bob On Sun, 07 Aug 2005 15:31:37 -0400, Bob Engelhardt wrote: I am going to make a threading dial for my Jet 1024. It seems pretty straight forward, but I want to do a sanity check and ask a couple of questions. 1. My Logan 200 and the Jet have the same lead screw (8 tpi). I assume that this means I should use a 16 tooth dial gear, as that is what the Logan has. 2. The lead screw looks like an Acme thread, could it be something else? If so, how would I figure out what it is? 3. What is this kind of gear called? I.e., when I call Boston Gear, what should I say I need? Is "To fit an 8 tpi Acme thread sufficient"? Thanks, Bob rgentry_at_oz_dot_net _AT_ = @, _dot_ = . to eMail |
Ned Simmons wrote:
... you won't be able to buy a stock gear of the proper pitch. ... I just found a gear! The Logan company has a replacement gear. But ... it's $45 gasp!. I happen to have a '71 Logan parts catalog where that part is $5.75. A vivid example of the power of compounded inflation - that is only about 6% per year, compounded. I think that I'll keep looking, Bob |
It really isn't that hard to make one. You need to make a hob by
making a copy of your lead screw (left hand thread), mill a couple of teeth and relieve it. Make a mount for your toolpost for the blank to rotate, put the hob in the spindle between centers, and advance the blank into it. You don't even have to harden the hob it you make a brass gear. It helps to gash it first to be sure you get the right number of teeth, otherwise you might get one mor or less than you need. A spin indexer is close enough for this step. To make the hob without a threading dial, just don't disengage the half nuts. It gets a little tedious and you may have to rotate the spindle by hand at times, but it can be done. |
For a threading dial, you could make the gear out of various plastics.
Nylon and Deldrin would probably be better choices, but I have made gears out of Lexan ( Hey it was what I had ). Dan paul wrote: You don't even have to harden the hob it you make a brass gear. |
paul wrote:
... make one. ... make a hob ... Make a mount ... make a brass gear. ... Oh - I like that. Another skill curve to climb ("because it's there"). Bob |
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DE wrote:
There is an article on making said gear with a lathe on a the yahoo SB10k group. ... Thanks. I "joined" the group and found the article. |
Ken Sterling wrote:
check this out.... ebay item #7536944404 ... Duh - why didn't I think of that. eBay! Of course - you can get anything on eBay. I checked the Completed auctions - there were some dials that were bargains and some weren't ($110??? - no way). Thanks, Bob |
Bob Gentry wrote:
... Home Shop Machinist, May/June 2000, page 38, Peter Lott has a four page article called " the Lathe Thread-Chasing Dial- - - ... Just what I need! HSM doesn't have that back issue and none of the Massachusetts libraries subscribe, but I'll have our librarian do a nationwide search (ain't the 'net wonderful?). Thanks, Bob |
Bob
My Enco 1024 has an original threading dial. I also have an Atlas 10" thread dial and a Logan 9 with thread dial. I'd be happy to make any measurements or comparisons that would help. - - Rex Burkheimer WM Automotive Fort Worth TX |
Rex B wrote:
.... I'd be happy to make any measurements or comparisons that would help. Thanks, I think that I'm all set. I've been looking around and I'm pretty confident about it. I was kinda in the dark about the number of teeth on the gear. Scott Logan (I think it was) in a Yahoo post explained it: the number of gear teeth divided by the screw tpi gives the highest number on the dial. E.g., 16 / 8 = 2, the dial has "1" & "2". The number gives the fractional pitch possible. E.g., 1/2 for 2, 1/4 for 4. Bob |
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Bob Engelhardt wrote: Al A. wrote: ... the threading dial I use on my 1024 (the twin of yours...) is from a 9" South Bend, same 8TPI lead screw, but the gear on the threading dial is 32 teeth. ... Your dial is rotating at half the speed (relative to the lead screw) as a 16 tooth dial. Does that mean that your dial has twice as many marks? There are 4 marks on my Logan dial: "1" & "2" 180 degrees apart and a "|" between them. My 12x24" Clausing (with an 8 TPI leadscrew) has four numbered markings 1, 2, 3 & 4, with four index marks half way between them. I suspect that is what you would need with a 32 tooth pickup gear. BTW One thing which I have not seen mentioned yet in this thread is that you will either have to cut your teeth at a slight angle (to match that of the Acme thread on the leadscrew), or to mount the shaft of the dial at an angle to allow the gear faces to line up with the leadscrew thread. It is not much of an angle (precisely how much depends on the diameter of the leadscrew in combination with the thread pitch. (It calculates out to 2.28 degrees with a 1" diameter 8 TPI leadscrew.) In either case, you may have to make corrections to the gear form to compensate for the angle. Be glad that you're not making a threading dial for a Metric leadscrew. That has to have four different gears -- all of which mesh with the leadscrew, one at a time, to handle all of the pitches common in the metric system. (This is one of the places where the Imperial system works out easier, because so many of the threads are a power of two relationship with other threads.) When you need to handle a 1.00mm, 0.80mm, 0.60mm, 0.45mm and other such, the design of a threading dial gets a bit more complex. And, of course, there is an additional bit to the threading charts to tell you which pickup gear to use with a given thread. :-) 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 --- |
Bob Engelhardt wrote:
I am going to make a threading dial for my Jet 1024. ... Thanks for all the replies in this thread. I have finished my dial, after many distractions. Here is a pictu http://home.comcast.net/~bobengelhardt/thread-dial.jpg I made the gear by hobbing a piece of plastic, unknown lineage. But it machined real nice - long smooth curls, very waxy in appearance. And strong (tensile). The threading dial that I copied had a spur gear, but I cut a worm wheel, to fit the worm lead screw. The tool I ground to cut the hob was not very precise, but it works. I "gashed" the gear on the lathe by using the feed gear train to step the spindle. I also hobbed the gear on the lathe with the hob between center and by making a blank holder to fit the lathe tool holder. There is a spring under the head of the mounting SHCS. It supplies enough pressure to hold the gear against the screw, but allows the dial to be swung away. Thanks again, Bob |
Bob Engelhardt wrote:
I am going to make a threading dial for my Jet 1024. ... Thanks for all the replies in this thread. I have finished my dial, after many distractions. Here is a pictu http://home.comcast.net/~bobengelhardt/thread-dial.jpg I made the gear by hobbing a piece of plastic, unknown lineage. But it machined real nice - long smooth curls, very waxy in appearance. And strong (tensile). The threading dial that I copied had a spur gear, but I cut a worm wheel, to fit the worm lead screw. The tool I ground to cut the hob was not very precise, but it works. I "gashed" the gear on the lathe by using the feed gear train to step the spindle. I also hobbed the gear on the lathe with the hob between center and by making a blank holder to fit the lathe tool holder. There is a spring under the head of the mounting SHCS. It supplies enough pressure to hold the gear against the screw, but allows the dial to be swung away. Thanks again, Bob Nice, Bob. However, the "spring under the head of the SHCS" has me concerned. Do you tighten the SHCS to "prevent" the gear from moving away from the lead screw? If not, I think I would recommend that you do, to prevent a little piece of swarf from making your dial "jump a tooth" when you're not looking..... could ruin a good project someday G Glad you're now ready to start doing some threading..... Ken. |
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