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oxford
10-24-2012, 06:49 PM
The nut was wore on my compound slide on a clausing 5914. I figured the screw threads were probably wore a little but I could tell no difference from the center threads to the ones on the ends of the screw so I thought they weren't too bad. I decided would make a new nut and ordered a piece of acme rod to make a tap out of. I got a piece of general 3/8-10 acme rod. The rod will not screw into the old nut and the threads don't look like the screw. The new rod the threads are wider(pitch is the same) and don't look as deep.

Is there a chance that the old screw is that worn evenly over the entire length and wore the nut to the point that the new rod won't thread in? Is it something with using the general rod vs a precision one?

John Stevenson
10-24-2012, 07:20 PM
If the Clausing is the same as the Colchester that it looks to be based on, model i mean then chances are they are two start threads.

You might be better off making a delrin nut.

http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-leadscrew-nuts-the-easy-way

oldtiffie
10-24-2012, 07:33 PM
The nut was wore on my compound slide on a clausing 5914. I figured the screw threads were probably wore a little but I could tell no difference from the center threads to the ones on the ends of the screw so I thought they weren't too bad. I decided would make a new nut and ordered a piece of acme rod to make a tap out of. I got a piece of general 3/8-10 acme rod. The rod will not screw into the old nut and the threads don't look like the screw. The new rod the threads are wider(pitch is the same) and don't look as deep.

Is there a chance that the old screw is that worn evenly over the entire length and wore the nut to the point that the new rod won't thread in? Is it something with using the general rod vs a precision one?

If the lathe is still usable and any back-lash in the screw is not causing a problem why not leave it as it is until of unless it really is a problem.

A moderate amount of nut or screw wear should not be a problem.

macona
10-24-2012, 07:37 PM
I am kind of surprised that there was enough use of a compound to wear the screw. How much backlash was there?

Mcgyver
10-24-2012, 07:52 PM
Is there a chance that the old screw is that worn evenly over the entire length and wore the nut to the point that the new rod won't thread in? Is it something with using the general rod vs a precision one?

I would say impossible.

This may seem too obvious, but you did buy a left hand screw, right? Everyone one I've touch uses a left hand screw so you get the motion of clockwise rotation moves the tool toward the work.

end of day, wear here doesn't matter that much here...I'd be more concerned about the ways and what they're like if the screw is worn out

oxford
10-24-2012, 08:38 PM
The thread is right hand on the compound and left on the cross slide on this lathe. The rod I got is right hand. I have not used the lathe since I got it. I have it most of the way apart for cleaning and figured I would address some problems(or future problems). Oldtiffie, the screw that came out is a single start. I did not check backlash on the dial, but when I grabbed the tool post I could move it back and forth probably a 1/16". I was going to just make a nut using evans method for the stock screw, but I figued that it would be easier to make the tap and make the nut out of solid delrin.

Something else on this. The screw is a 3/8-10. The compound dial takes .200" to make 1 revolution, wouldn't that mean it is only going to move in a half of thou for every 1 on the dial? Souldn't the compound be a 1 to 1? Maybe I am not thinking about this right.

macona
10-24-2012, 08:47 PM
Are you sure the slop was in the screw and not the thrust assembly on the dial?

There are two kinds of dials, direct reading and diameter reading. Direct reading dial tell you how far you are moving the slide in, diameter dials tell you how much you are taking off the diameter of the stock.

oxford
10-24-2012, 08:57 PM
There may have been some slop in the thrust but there is definitely slop in the screw, nut or both. I still think that most of it is in the nut.

I would think that the compound would be a direct read dial. There is a Clausing 6300 at work which is very similar to the 5914 that uses a direct read dial, I don't see what the benefit would be to change it to a diameter read dial there.

Mcgyver
10-24-2012, 08:58 PM
Something else on this. The screw is a 3/8-10. The compound dial takes .200" to make 1 revolution, wouldn't that mean it is only going to move in a half of thou for every 1 on the dial? Shouldn't the compound be a 1 to 1? Maybe I am not thinking about this right.

could it be a two start like John suggested? that would look like 10tpi but advance like 5tpi or .200 per rev....or its the style of lathe where the dail indicates how much is taken off the diameter vs the infeed

oxford
10-24-2012, 09:09 PM
I belive it is a single start screw. I marked 1 thread and made one rotation and ended up at the thread next to it. Could it be possible that these are not factory parts and someone did a poor job making the acme thread and made the nut to fit?

luthor
10-24-2012, 09:31 PM
10 tpi single start will move the slide .100". Maybe the dial is wrong or you are reading it incorrectly.

Chuck K
10-24-2012, 09:32 PM
The thread is right hand on the compound and left on the cross slide on this lathe. The rod I got is right hand. I have not used the lathe since I got it. I have it most of the way apart for cleaning and figured I would address some problems(or future problems). Oldtiffie, the screw that came out is a single start. I did not check backlash on the dial, but when I grabbed the tool post I could move it back and forth probably a 1/16". I was going to just make a nut using evans method for the stock screw, but I figued that it would be easier to make the tap and make the nut out of solid delrin.

Something else on this. The screw is a 3/8-10. The compound dial takes .200" to make 1 revolution, wouldn't that mean it is only going to move in a half of thou for every 1 on the dial? Souldn't the compound be a 1 to 1? Maybe I am not thinking about this right.

10 tpi moves the compound slide .100 per revolution....your dial is reading .200 which is the diameter reduction with each revolution....assuming your perpendicular to the work.

oxford
10-24-2012, 09:40 PM
Are there lathes that use this for the compound? I can see using it for the cross slide, but can't see where it would benefit on the compound. Can anyone with a 5900 series confirm what the dial should read vs the movement. Maybe originaly there was a 2 start screw in there.

Dr Stan
10-24-2012, 10:48 PM
This is strange, most if not all of the lathes I've used had compounds that were "direct reading" or moved .001" for every .001" on the dial. A 10 TPI compound screw should result in .100" travel for every revolution, so I find it quite odd that it has a .200" graduated dial.

I scanned the manual for the 5914 Clausing, but did not see any indication of what the travel should be of the compound. If you want to read it, it is available here: http://vintagemachinery.org/pubs/181/3407.pdf

Paul Alciatore
10-24-2012, 11:12 PM
It should be easy to determine if the dial is direct reading or diameter reading. Just count the divisions on it. If it has 100 divisions, it is direct reading. If it has 200 divisions, it is reading in terms of the diameter removed. Of course this assumes a 10 TPI. single start lead screw.

I would wonder if perhaps the compound and the cross feed dials have become reversed.

dfw5914
10-24-2012, 11:14 PM
The compound on my 5914 advances .100 per revolution. The dial has 200 increments.

Forrest Addy
10-25-2012, 03:24 AM
Ideally one should have a gear tooth vernier caliper handy but there's a simple (and a whole lot less exensive) way to check the wear of your Acme lead screws.

Most wear occurs in the part of the screw that sees the most use (duh!) and the very ends see little. There's a way of checking Acme screws by the "best rire size" where a gage wire (straight shank of a drill, dowel pin etc) is selected to fiit in the thread space so it's flush with the thread OD. Rummage in your drill set for a best wire size at the un-worn portion of the thread and again at the worn portion. Work the math if you wish but you don't need to.

Use the un-worn best wire size as a gage to chase the thread of the new screw. Make the thread of the new screw to to comply with the tooth space of the unworn part of the screw. Cut the thread with 2" of extra length. Part it off for use as a gage when boring the threads of the nut.

JoeLee
10-25-2012, 08:44 AM
Both dials on my 5913 read .200. The threads on the original screws are ground. When I replaced the cross slide screw the first thing I noticed was the threads were turned......... cheaper version I guess. I find it hard to believe that the compound screw is worn unless the slide was over tightened and used a lot. I don't believe that either screw are standard ACME thread pitches. I would double check the thrust bearing behind the dial and the associated parts.

JL.....................

justanengineer
10-25-2012, 09:24 AM
Realistically, the direction and pitch of the thread make little difference in the grand scheme of things here. If you want to be picky and have it like new again, cut yourself a nut and a screw to match. You could always just convert it from whatever it is now to direct reading on the dial and a standard acme thread.

As others have said, be sure to confirm both the thrust bearing and gibs are adjusted properly.

BillTodd
10-25-2012, 09:50 AM
Hmmm, The Top-slide usually has a right-hand thread (the nut stays still while the handle and screw move) . Cross-slides and tail-stocks are usually LH (the nut moves)

If the TS dial has .200" marking it would suggest the original screw had a .200" lead so was either a single start .2" pitch or a two start .1" -

I wonder if, as speculated above, someone has replaced a two start screw thinking it was a 0.1" single start? If not perhaps the screw is not ACME , i.e. could it be a square thread or, if metric, trapezoidal ?

Bill

Duffy
10-25-2012, 10:07 AM
Is there any possibility that this is a STUB ACME thread? The pitch will be the same, but it sure wont fit the nut!

RussZHC
10-25-2012, 02:23 PM
Duffy: that is what I was beginning to wonder too...

"jayhawkman" on PM at one time sold a repair kit, with a 4" chunk of 4140 round and a 4" length of 3/8" - 10 precision acme" for this model of lathe, so I assume those are correct sizes (thread and diameter, no mention of number of starts))

rohart
10-25-2012, 06:27 PM
Colchesters have a dial that reads diameter. So a 3/8x10 compound screw will advance 0.100 per revolution but take 0.200 off the diameter. You must ignore the dial when you measure the pitch of the screw. Put a gauge on the compound, and rotate the dial until you have a handle on what's going on.

Colchester Bantams, as JS observed above, also use a two-start on the compound. This would mean that the profile of the thread would conform to a 5 tpi thread.

lane
10-25-2012, 06:49 PM
For now don`t worry about the dial . Lay the screw on a bench next to a steel rule and count the threads on the original screw are use a regular thread pitch gage . Try 10 threads per inch first . I bet it is 5 threads per inch with 200 on the dial.also mike the diameter in a few of the unworn places. The neet think about a acme thread is they are NOT necessarily a specif fractional size . The screw on my lathe is a 5 pitch screw but is .540 diameter not .500 as you would think. Try the measurement thing and check back.

oxford
10-25-2012, 07:30 PM
Thanks for the replies. It a 10tpi screw. The dial also has .200" for one rev. At least someone confirmed that there slide only moves .100" for every rev and there dial also has .200" on it. That clears up one thing, that it is the correct thread pitch and a single start screw, although I still find it odd that the compound has this. I am also wondering now if the threaded rod that was sent from McMaster is a stub acme thread, that would make some sense. Here is a pic of the old screw next to the new rod.

http://i296.photobucket.com/albums/mm177/klx411/DSC04596.jpg

As far as making a acetel nut using Evans method, how would you go about making a nut like this. I was thinking of making a nut out of some crs but instead of threading just make a straight bore then doing a slight press of the molded acetel nut into it then putting a roll pin through to hold it in place. Any other ideas.

http://i296.photobucket.com/albums/mm177/klx411/DSC04598.jpg

caveBob
10-26-2012, 12:46 AM
As far as making a acetel nut using Evans method, how would you go about making a nut like this. I was thinking of making a nut out of some crs but instead of threading just make a straight bore then doing a slight press of the molded acetel nut into it then putting a roll pin through to hold it in place. Any other ideas.

http://i296.photobucket.com/albums/mm177/klx411/DSC04598.jpg

Don't know if parts for your Clausing are interchangeable with an Atlas 12"... if this one is:

http://www.tools4cheap.net/prodimages/atcomplg.jpg

...you can get it at Tools4Cheap here: http://www.tools4cheap.net/proddetail.php?prod=nutatlas12comp

Mcgyver
10-26-2012, 08:51 AM
Thanks for the replies. It a 10tpi screw. The dial also has .200" for one rev. At least someone confirmed that there slide only moves .100" for every rev and there dial also has .200" on it. That clears up one thing, that it is the correct thread pitch and a single start screw, although I still find it odd that the compound has this. I am also wondering now if the threaded rod that was sent from McMaster is a stub acme thread, that would make some sense. Here is a pic of the old screw next to the new rod.


well its not a two start and its going the right direction.....

maybe Duffy nailed it....that bottom one doesn't look deep enough. Have you measured it? The depth of the acme should be half the pitch, much less for the stub, ie minor diameter should be P (pitch) smaller than major

If they sent you the wrong one, get it replaced.

if measurement shows its not a stub, measure with thread wires and check machinery's handbook.....if its within tolerance it'll fit. Do the same at the end (unworn section) of the original.....there's only so many things that could be wrong and they are easily checked.

The nut basically doesn't matter for accuracy or anything else....might be easiest just to use the original if you can get the right screw

JoeLee
10-26-2012, 09:43 AM
I wouldn't make the nut out of any plastic type material, simple reason being it's too soft and will give too much under a load.
Especially since that nut extends about an inch below the bottom of the slide. You know it's going to give.

If I was dead set on making one I would use bronze or brass. You could try making a tap out of the ACME rod by turning a taper on it and then slotting the taper and relieving one side of it a bit. In other words you would almost be making a self tapping screw out of the ACME rod. That may do some cutting in soft material.

JL................

oxford
10-26-2012, 10:03 AM
If I was dead set on making one I would use bronze or brass. You could try making a tap out of the ACME rod by turning a taper on it and then slotting the taper and relieving one side of it a bit. In other words you would almost be making a self tapping screw out of the ACME rod. That may do some cutting in soft material.

JL................

That was my original plan. I figured that the original screw must have a little but of wear and using a piece of new rod to make a tap would cut the threads with a little interference so it would work good on the old screw. Then when the rod showed up and was different from the old one is where things went down hill. I will have to try and measure the new screw and find out if it is speced for regular 3/8-10 acme threads.

I could always make a new nut with the new rod and then put a piece or the rod onto the old screw, but for that much work I think I would be better off finding some 2 start acme so I can get the slide movement to equal what the dial reads. Anyone have a short piece of 3/8-10 RH 2 start acme rod they want to part with.

I am seeing this going back together with the old nut and screw for a while untill I can get things sorted out.

cameron
10-26-2012, 11:08 AM
Looking carefully at the compound screw and the screw beneath, it appears they are not the same pitch. There's almost a half pitch difference in 29 threads. Doesn't that suggest the compound thread pitch is 2.5mm?

(2.54 -2.5)X29 = 1.16mm = .046", roughly 1/2 pitch.

JoeLee
10-26-2012, 11:14 AM
Looking carefully at the compound screw and the screw beneath, it appears they are not the same pitch. There's almost a half pitch difference in 29 threads. Doesn't that suggest the compound thread pitch is 2.5mm?

(2.54 -2.5)X29 = 1.16mm = .046", roughly 1/2 pitch.
I noticed that too ! You can see that the threads on the rod start to get ahead of the threads on the original screw. You can forget reding the dial with that rod. Did you check with the Clausing service center to see if the screw and nut are still available???

JL...............

Bill Pace
10-26-2012, 12:19 PM
I've run into this acme thread incompatibility phenomenon a couple times, the latest also being a Clausing in the 100 series.

Lane said he had seen it often also and thought it was that the mfg did proprietary threads??

I also got a length of 1/2-10 thread from Mcmaster, but I also got one of their 'general purpose' acme nuts that matches it also. Your existing nut looks exactly like mine did, 3/4 diameter?? - what I did was to turn the Mcmaster nut down to 3/4" dia and then mill the existing nut/threads away to match the diameter of the new nut and silver soldered them together (take care to get the new nut in line with the travel path) I also did this on a cross feed screw and also with a tail stock screw.

http://www.mcmaster.com/#general-purpose-acme-nuts/=jw1gq9

Mcgyver
10-26-2012, 01:09 PM
I noticed that too ! ........

I did as well, but is seemed so slight I figured it was parallax and maybe a bit of wear at one end.... oxford, since you're the only who can view and test, what say you? are they in fact the same pitch when compared over their lengths?

Peter.
10-26-2012, 01:52 PM
I wouldn't make the nut out of any plastic type material, simple reason being it's too soft and will give too much under a load.


I don't agree with that at all.




http://i296.photobucket.com/albums/mm177/klx411/DSC04596.jpg

As far as making a acetel nut using Evans method, how would you go about making a nut like this. I was thinking of making a nut out of some crs but instead of threading just make a straight bore then doing a slight press of the molded acetel nut into it then putting a roll pin through to hold it in place. Any other ideas.


That's exactly what I did on my lathe and it worked just fine.

oxford
10-26-2012, 03:27 PM
As far as I can tell by eye the thread pitches are the same. It will sit tooth to valley with no apparent gaps(except in depth). I will agree that they do look different in the picture. I think it is camera angle and shadows and the original screw didn't lay exactly flat next to the new screw.

As far as a manufacture specific thread, it could be though the piece of 5/8-10 LH acme rod that I got for the cross slide fits into that nut. That nut is also wore pretty bad so it may not be saying much. I know that the nut is available from Clausing and probably the screw as well although I don't think I would want to know what the cost of the screw would be.

JoeLee
10-26-2012, 04:22 PM
Well last year I replaced the cross slide screw on my 5900 and the screw and nut assy. cost me $225. There was a bit more work involved in making that screw because my lathe has the taper attachment, the dial end of the screw is splined or broached internally and the opposite end is turned down to fit the end bushing. Your compound screw is short and simple, so is the nut..... it's not a T nut. It has to be less than what I paid for my cross slide screw. I would with out a doubt at least inquire about the price.

JL................

oxford
10-26-2012, 04:46 PM
Was that $225 the cost from Clausing? I was quoted over the $300 mark($325 I think) for the cross slide shaft and $56 for the nut. This was for the standard screw, not the one for the taper attachment. I got a piece of precision threaded rod for that to splice in and I am going to attempt making a steel t-nut with the Evan acetal nut insert.

I was going to do the same for the compound except re-use the old screw since it didn't look like there that much wear on it. I then decided it would probably be easier to get a piece of rod, make a tap and a solid nut of acetal. Thats where the problems started.

JoeLee
10-26-2012, 08:40 PM
Yes the $225 was the cost of the cross slide screw and nut. This was the screw used if your lathe had the taper att. Internally splined as I mentioned in my previous post. The standard screw (no taper att.) was much cheaper.
I just can't see that short screw and nut costing $300. Something doesn't sound right.
Below is a picture of my cross slide screw.

JL...............

http://i911.photobucket.com/albums/ac317/JoeLee09/Clausing%20Cross%20Slide%20Screw/InternalSpline.jpg
http://i911.photobucket.com/albums/ac317/JoeLee09/Clausing%20Cross%20Slide%20Screw/ShaftTail.jpg

oxford
10-26-2012, 09:54 PM
The cross slide screw was $300+, I didn't get a price for the compound screw.

JoeLee
10-27-2012, 10:19 AM
Usually the screw comes with the nut. Your 5914 is a little bigger of a machine than my 5900, but I can't see there being that much difference.
Perhaps the price has gone up?? The compound screw should be much cheaper.

JL...................

Mcgyver
10-27-2012, 10:44 AM
oxford, you were on the right track with buying threaded rod.....and the wheels fell off the cart on it fitting the nut. So the next step is measuring - did get a chance you to measure the threads as suggested? Measure the one you bought and an unworn section of original with mic and thread wires. If you don't have them, you can use wire in a pinch but the thread wires can be bought for small dollars and are something the tool box should have Since pitch, direction and starts aren't the issue, there are only so many things it could be - all determined by measuring

1) the threaded rod you bought is out of tolerance
2) the threaded rod is a stub acme
3) the original screw is custom size

1 & 2 get fixed by getting the right thread stock. 3) gets fixed by making the screw yourself. Not hard since you've measured with thread wires an unworn section of the original.



The cross slide screw was $300+, I didn't get a price for the compound screw.

:eek::eek:

They send a machine shop the drawing, then mark it up 100% or more. The markup on parts is rude.

With more money than time I can't fault buying it out, otoh hand we have lathes and its a good project. Buying a length of acme threaded rod saves some of work, or you could just make the whole thing.

oxford
10-27-2012, 02:34 PM
I measured the depth of thread the best I could. The book I have here at the house said depth should be 1/2 of the pitch plus .010" for clearance for standard acme. So 3/8-10 should be .060" with clearance. It did not give specs for stub acme in it. The old screw I got right around .060" in the center and a little less on the ends. The rod from McMaster only measured around .041" of depth. I think that this would make it a stub acme from what I can gather for specs on the internet (I saw where it is around 2/3 less depth than regular acme). I guess I am going to have to give McMaster a call, I hope they don't plan on having me pay for the return shipping.

Mcgyver
10-27-2012, 05:40 PM
stub should be 1/3P (yes I had to look it up lol), plus some clearance (and inaccuracies in measuring if you say you are using the rod of a caliper or such....not sure how you're going at it) .041 could be stub. As I think about, depending on the class of thread, there might be that much clearance. It's certainly not 1/2P that you want so I'd say Duffy was right.

i agree call them...imo the easiest path to fixing the problem imo is getting back on the one you were on....but with the right screw stock. I'd use the original nut, it does not affect accuracy.

oxford
10-27-2012, 06:51 PM
I was measuring the best I could with a drill bit, although I am lacking on the small wire sizes. I checked the original screw with a .062" drill bit that I ground the sides on. I know not the best but probably pretty close.