Cincinnati Toolmaster X lead screw repair

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torchmd
Posts: 26
Joined: Wed Jan 12, 2011 9:43 am
Location: Greenville, SC.

Cincinnati Toolmaster X lead screw repair

Post by torchmd »

Hello!

Hope someone can help me out with this. I bought a Cincinnati tool master model 1, with a Bridgeport J-head rather than the original Cincinnati head... It currently lives in my garage like a millennial, just taking up room and leaving greasy stains on the floor. :(. I thought I got it for a decent price, and it would do for what I wanted, but I am finding it may be a white whale.

So, I have been trying to fix some of it's shortcomings. It needs some repair, and some love. But the repair is becoming more difficult than I anticipated. The head is easy, as parts are available. but the table and such is much more challenging. Parts are just either not available, or so damn expensive, it is like I am trying to transplant organs! So, I'm trying to fix some stuff. I could get a Bridgeport lead screw for about 300$, but it is not a 1:1. I am not confident to try and retrofit the lead screw...

Now, in its prior life, its as operated by drunken monkeys, so the table is just beyond ugly, but still usable. I was planning on cleaning it up some with some epoxy. It was missing some parts, and apparently was abused to get it back into working order. The x -axis lead screw has had the nut completely stripped off. Replacement does not seem to be an option. I have looked for machinists near me to see if I can get it fixed, but keep getting either no answer what so ever, or "sorry buddy, can't help you with that". I think the latter is because they only do cnc work...

so, I'm looking for ideas. Originally I had two ideas... 1) turn off the old threads down to 5/8 od, and turn a new 5/8 thread, or 2) turn off the old threads, and turn a new collar with 7/8 threads and an internal ID that will fit on the new OD of the shaft end and either braze it, or lock tight it on, which should be ok. I guess I could key and pin it also. But I think lock tight would work.

My problem, I do not have a lathe big enough to turn this shaft. I had thought that I could set it up on my 10/22 lathe with some steady rests, drill the end of the shaft and thread it with a tap, and turn it on the lathe with a dog, to be able to turn the threads off, but wanted to reach out before I injured myself and see if anyone else had thoughts... IT should be an interesting discussion if nothing else.

Any help would be appreciated.

Michael
Rich_Carlstedt
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Location: Green Bay Wisconsin USA
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Re: Cincinnati Toolmaster X lead screw repair

Post by Rich_Carlstedt »

Michael, It;s been almost 50 years since I worked on a Cinnci Tool Master
What is the size of the X axis leadscrew ( D , L, and pitch )?
It is RH as I recall
Also doesn't that mill have zero-backlash nut on the leadscrew ?

Are you going to install a DRO on the mill ?
If so, then pitch and screw quality become non rec. for a replacement
Rich
torchmd
Posts: 26
Joined: Wed Jan 12, 2011 9:43 am
Location: Greenville, SC.

Re: Cincinnati Toolmaster X lead screw repair

Post by torchmd »

Hey Rich,

I apologize. It is a 36 inch table, so the lead screw is 43 inches long, with 24 inches acme threaded, and 1 1/4 diameter. The thread is 6tpi, IT does have a zero backlash nut on it, and I do have a DRO so not worried about that. I think I just need to get the threads fixed, but having trouble finding someone who can do it, or figuring out how to do it myself! :(

THank you!

Michael
Bob D.
Posts: 381
Joined: Thu Jun 21, 2012 10:43 pm
Location: Saco, ME. USA

Re: Cincinnati Toolmaster X lead screw repair

Post by Bob D. »

Some pics are in order of just what you are trying to deal with. My take is the acme threads are ok. You have spoiled threads for a retaining nut on one end? If that is the case, I would set it up in a lathe and pick up those old threads and then keep going until you have a serviceable thread of whatever diameter it comes out. Then make a bastard nut to fit. Can do any thread pitch/dia you want on a lathe, not just what is standard.
You just need to find someone to do it if your lathe isn't big enough....
3/4" Juliet II 0-4-0
3/4" Purinton Mogul "Pogo"
3/4" Hall Class 10 wheeler
3/4" Evans Caribou/Buffalo 2-8-0
3/4" Sweet Violet 0-4-0
3/4" Hunslet 4-6-0
3/4" Kozo A3. Delayed construction project

1 1/2" A5 Camelback 0-4-0
torchmd
Posts: 26
Joined: Wed Jan 12, 2011 9:43 am
Location: Greenville, SC.

Re: Cincinnati Toolmaster X lead screw repair

Post by torchmd »

Hey Bob,

I did something wrong, I thought I attached pictures… typical. 🤦🏻‍♂️ I will see if I can add them here.

Your summation is correct. I have buggered retaining threads. and turning them off to new threads was my goal, but the lead screw won’t fit on my 10/22 lathe, and I can’t find anyone near me who can do the work, surprisingly enough. The machine shops I have called either don’t call back, or “don’t do that kind of work”. ?!? I guess in this day and age, just buying a new one is the best option, at least here.

So, my question is, is there a way to turn off the lead screw threads in a small lathe?

I thought about it last night, here’s what I came up with: The lead screw was originally turned between centers apparently, as there is a center hole on each end. I could drill this out, and tap it to say 3/8 threads, then make a threaded insert from square bar that will screw into this tapped hole. Then I can hold the lead screw in a couple of steady rests, and center the insert in a 4 jaw chuck to turn the threads. THere will be a lot of lead screw hanging off the end of the lathe, and I have no way of holding this beyond about the center. Will this be safe? It seems like a lot of material hanging out in the middle of no where….

Any ideas would be appreciated.
Attachments
78BB7583-2767-45DF-915F-2EA47E15508E.jpeg
26ED91F3-5C2B-43E6-854E-213BBF0F94F2.jpeg
EEE3CE15-3950-44C8-A050-BA822FC776B5.jpeg
F561C7CD-42EF-4192-9E0F-1D5FFD375D51.jpeg
kl7sg
Posts: 75
Joined: Thu Oct 08, 2020 12:00 pm
Location: Springtown, TX

Re: Cincinnati Toolmaster X lead screw repair

Post by kl7sg »

What is the diameter of the leadscrew?
On my lathe, you can run the leadscrew thru the chuck as far as you need.
So a long piece, like yours, can be turned and threaded if the diameter is less than "1.5 inches"
Anyway, I think I can do it if your not in a hurry.
Have a nice day,

Mike
Bob D.
Posts: 381
Joined: Thu Jun 21, 2012 10:43 pm
Location: Saco, ME. USA

Re: Cincinnati Toolmaster X lead screw repair

Post by Bob D. »

Yep, those are boogered. I would really hate to lose the original center. You don't list your location. You need to find a small shop that has a lathe with a large enough spindle thru hole so the lead screw can be chucked up. Straight forward job. Or a bed long enough to work it between centers. Maybe a Vocation school?
I don't think you will have enough support with your idea. 3/8’ bolt doesn't have much cross section.
You have a bit of threads at each end of the damage. How about an adjustable die that fits that original thread. Recut working down until it is as closed up as possible. Make a nut thick enough to engage the entire thread area with undersized threads. I think you will have enough engagement to assemble. Then drill and tap the end 3/8” fine thread. Use an Allen bolt and washer to buttress up against the new wide nut. That will back up your weakened threads from shearing.
Only hand tools needed for the leadscrew repair.
3/4" Juliet II 0-4-0
3/4" Purinton Mogul "Pogo"
3/4" Hall Class 10 wheeler
3/4" Evans Caribou/Buffalo 2-8-0
3/4" Sweet Violet 0-4-0
3/4" Hunslet 4-6-0
3/4" Kozo A3. Delayed construction project

1 1/2" A5 Camelback 0-4-0
whateg0
Posts: 1114
Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: Cincinnati Toolmaster X lead screw repair

Post by whateg0 »

Where are you located? There are a lot of, including me, who would be willing to help you out. I can fit it through my spindle. I don't really think losing the center is that big of a deal in this case. It's never going to be a new part again. But it's a pretty easy deal to turn the end down and put a new thread on.
John Evans
Posts: 2366
Joined: Tue Jan 20, 2009 9:33 pm
Location: Phoenix ,AZ

Re: Cincinnati Toolmaster X lead screw repair

Post by John Evans »

And here is another excellent reason why people should at least show a state etc. in their profile ! I would be happy to help out as my Clausing will pass 1-3/8+ thru the HS.
www.chaski.com
torchmd
Posts: 26
Joined: Wed Jan 12, 2011 9:43 am
Location: Greenville, SC.

Re: Cincinnati Toolmaster X lead screw repair

Post by torchmd »

I will fix that now. It was an unintentional omission.

I’m in Greenville South Carolina.

The lead screw is 1.25 in diameter.

That is what I was worried about with trying to support it hat way. Plus with a hole drilled in the end and turning it down it is getting really thin. 😬
whateg0
Posts: 1114
Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: Cincinnati Toolmaster X lead screw repair

Post by whateg0 »

Looks like about $30 ships it FedEx ground, $60 round trip, which is still far less than making or buying a replacement.
torchmd
Posts: 26
Joined: Wed Jan 12, 2011 9:43 am
Location: Greenville, SC.

Re: Cincinnati Toolmaster X lead screw repair

Post by torchmd »

That would be awesome.

I’m getting more like $60 each way. The shaft weighs about 35#, so 40# with packing, 44 inches long, 3 x 3 box… UPS says 56.80 one way…. I may have to consider that, but the cheapskate in me wants to avoid shipping the shaft half way across the nation, at least for now. I may have no other choice though. I called another machine shop today, and the guy stopped me 5 seconds in to tell me the is backed up with his regular customers, and didn’t have time… :( The other thing I consider is that a new x-axis for a Bridgeport is only about 300$… we are at 40% the cost… of course, this isn’t a Bridgeport…. There is that. I have looked to see what the thread measurements are on the Bridgeport, to see if it would fit in the nut.

I’m going to wait a minute, but I sincerely appreciate the offer. I may ask you in a bit if you would still be interested, if that is ok.

A million options, but no solutions… :(
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