Lead screw worn out

FCJimmy · Mar 4, 2015

I have an old (1970's) 12 1/4" swing Craftsman Commercial lathe that has a worn lead screw. The only one I could find (about 2 yrs ago) was listed at $457.20 !!!!! Does anybody here know a cheaper way around this situation? Could the screw be turned end for end so the worn area is farther away from the headstock, maybe? Or, is there someone who makes the same type of threaded rod in a stock "ready rod" form that cold be adapted to fit? Any ideas would be welcome at this point. :wall:

Wizard69 · Mar 4, 2015

FCJimmy said:
I have an old (1970's) 12 1/4" swing Craftsman Commercial lathe that has a worn lead screw. The only one I could find (about 2 yrs ago) was listed at $457.20 !!!!! Does anybody here know a cheaper way around this situation? Could the screw be turned end for end so the worn area is farther away from the headstock, maybe? Or, is there someone who makes the same type of threaded rod in a stock "ready rod" form that cold be adapted to fit? Any ideas would be welcome at this point. :wall:

Is it an acme thread? You can buy acme "all thread" fairly cheap but you would have to work out fixing it To the drive hardware. How well acme threaded rod would work depends upon the design of your machine and your creative skills.

You could also try one of the suppliers of Chinese machines to see if there is a lathe with a similar Leadscrew. You would have to rework that Leadscrew which of course requires a working lathe. The problem here is that this wouldn't be a trivial job and the Leadscrew likely wouldn't be cheap as a spare part anyways.

Either of those two avenues will start to make that $457 look cheap. Your other option is to cut a completely new screw, either yourself or have a local shop do it. Again that $457 will begin to look cheap.

goldstar31 · Mar 5, 2015

I would guess that this is a ? Left hand? thread. What has also to be considered is the clasp nuts.

However, for what it is worth( and I haven't seen the job), the leadscrew will probably be worn classically about 6 to 9 inches from the chuck end. So having checked the clasp nuts why not reverse the leadscrew. Again, if the leadscrew is really worn, I would doubt that the rest of the lathe is much good. My take whilst others may differ.

Norman

tornitore45 · Mar 5, 2015

What are the negative effects of this wear?
As long as you keep sufficient drag to engage one side of thread it does not matter what the gap to the other side of the thread is, 0.0002" or 0.050"
You can still make good treads.
Steel lead screw, bronze half nut... I would be looking at improving the nut.

RGS · Mar 5, 2015

It is 3/4" 8tpi and can be made with acme all thread. The issue is cutting the slot for power cross feed. Here is a link of one being made. There are a couple of more forum posts out there of someone making them but I was unable to find them now.

http://www.machinistweb.com/forum/showthread.php?t=2879&highlight=atlas+lead+screw

I have also heard of some turning the lead screw end for end as you mentioned.

Gordon · Mar 5, 2015

I have not seen your lathe but I had an Atlas lathe many years ago and the problem was the half nut was worn out. The half nuts are brass or die cast and wear easily. At that time I was able to purchase replacement parts. The Craftsman was made by Atlas so the parts are interchangeable so that gives you more places to look.

RGS · Mar 5, 2015

If you need new half nuts you can still order them from Atlas which is now Clausing. I order new ones last winter and they were about 35.00 dollars + shipping. The ones I order were PN of 10F12 but mine is an older Craftsman 12" not sure but I think they are the same. Phone # of 269-345-7155 or 800-323-0972.

Clausings web site http://www.clausing-industrial.com/partsService.asp

It is cheaper for new ones from Clausing than used ones on Ebay.

digiex-chris · Mar 5, 2015

don't forget the method squeezing two halfs of delrin (with the minor diameter of the thread bored out between them) around a short piece of the rod you used and then heating the end of the rod until the delrin squeezes into the shape of the thread in order to make half nuts (or leadscrew nuts for a mill, or whatever). Appears to work very, very well. That way, you don't have to do any threading with your now-worn leadscrew in order to prepare a new leadscrew. Just machine the ends to length and whatever's needed to drive it, which is often just simple cylindrical turning.

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

FCJimmy · Mar 5, 2015

Thank you all so much for your replies! Those links are fantastic, and I learned some really neat stuff as a result. The pictures tell the whole story, and that lathe is identical to mine. Yes, the split nut on mine is also a 10F12, and the price I got from ebay about 2 years ago was $60.77 ! I will look up the acme screw stock on the web, and I'm sure it will be much less than the $457.20 quoted back then also. I bought a Van Norman #12 mill about 6 years ago, and have never used it, as it was out at my Dad's shop, and very unhandy for me to get to, and I really had no large projects for which I needed it. I will now probably use it to make my lead screw slot, and am very happy I have it to use. By a crazy coincidence I just inherited a "Star" lathe, and a Chinese made Mill/Drill, and all the collets, cutting tools, degree attachment, vise, hold-downs, etc., so now have an abundance of machine tools from which to choose when building future projects, and feel truly blessed by the machinist gods

My first Father in law taught me how to use a little 9" lathe to make muzzle loading gun parts back in 1970 when I got home from Viet Nam, and I have been totally grateful for every minute of time and patience he provided to help me learn a lifetime hobby of amateur machining, among all my other hobbies through the years. I feel like this forum is the continuation of my "training", and really appreciate all the knowledge available here.

RGS · Mar 5, 2015

Atlas still stocks a lot of parts for our lathes and the price is often less than used on EBay. Unfortunately I don't think the lead screw is one of them. That is also a item that I need to make for mine.

Where are you located in NW Oregon?

RonGinger · Mar 6, 2015

Have a look at http://www.wedin.com/ They offer all sizes of lead screws and nuts. I purchased a screw and nut from them for my Clausing 8513 mill. I got just a length of screw and had to machine the ends myself.

FCJimmy · Mar 7, 2015

Thanks again for all the help. I checked with Wedin, and their stock lead screws were too short, and a little more money than I wanted to spend. I then checked McMaster Carr, and they were the answer. I can get the split nut from Clausing for $34.63, and can buy a 6ft. piece of precision ground acme thread rod from McMaster Carr for only $78.40! They had it in 3' or 6', and the 3' was just a little too short for my machine. I didn't ask about shipping, but I'm sure it won't be too terrible on either part. Now I just have to wait until I get my tax return and have a little "mad money" to spend

RGS · Mar 7, 2015

Here is another source for lead screw. You order it by the foot. Have never order from them myself but someone on another forum recommended them.

http://www.roton.com/Mating_Components.aspx?family=7059433

FCJimmy · Mar 9, 2015

You guys are the greatest!! I went from figuring I'd have to spend $517.97 plus shipping to get my lead screw and split nut (ebay prices), to now finding out I can make my own lead screw using 4' of acme rod from Roton, and a split nut from Clausing, and it will cost a grand total of $81.35 plus any shipping charges that may apply. WOW, what a difference a little networking can make! I will recommend this forum to anyone I run across who does machining, as we can all help each other through communication, for sure.

FCJimmy · Mar 11, 2015

RGS, sorry I overlooked your question before...I am a few miles north of Portland.

Kernbigo · Mar 29, 2015

mc master carr has acme threaded rod

FCJimmy · Mar 31, 2015

I just ordered a 6 foot piece of acme thread rod from McMaster Carr yesterday, so will be seeing it one day soon. I don't know how soon I'll be repairing the old lathe, as I now have a new one to use if I need it, but will probably fix it next winter when I get back to inside projects. Thanks again for all your help, and I will post pic's when I make the new lead screw.

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