Traub A25 Issue

Well,
I in the not so distant past, purchased a Traub A25 Screw machine... two vertical slides, longitudinal cut attachment, single tailstock. Got it up and running, but found that the clutch mechanism, and hence the cams, will not turn reliably...I expect a shear pin somewhere in the cam drive arrangement...occasionally it will revolve for a few turns, then stick. I do know that the machine had this problem before I received it, as it had been parted a bit (parts replaced). There are, no doubt, a few of the readership on the site familiar with the Traubs. Before I delve into the mechanism...any advice on the repair?

Purchased the machine for...$200, and it came with a complete set of manuals, complete collet set, complete gear set...no bar-feed, however it does have the optional bar shut-off.

I run an A42 occasionally and have an A25 in parts all over the place. Never worked on the clutch assembly. That said, it turns with the handle easily all the way through the cycle? The collet could be too tight or something else may in a bind to make the clutch slip. The bar is the same size so the clutch does not get alternately tight and loose?
You have checked to make sure the feed motor and sprockets are still turning when the feed stalls out?
I probably have the clutch around here but I doubt if I could find it, I tried to find the longitudinal turning attachment for some one else and could not find it(we have moved since the machine was taken apart).

Fred,
Yes, everything remains in operation...clutch, chain, gears...everything save the cam shaft that the clutch drives. I believe that the way it is operating, there is a sheared pin or lock-screws slipping...occasionally catching. What I am seeing is that the clutch is free and running, but the shaft does not turn when engaged. There is no work material thru the spindle at this time. The crank is difficult to turn through a cycle with the motor not running. The cam shaft doesn't really stall out...it randomly stops...catches, and then stops again. I will be dis-assembling the clutch from the cam shaft to determine how they lock up...there lies the problem...or not.

I am thinking you may have several issues. I just pulled the bar out of my A42 and cranked it by hand. The over all cranking resistance is minimal through most of the cycle with slight changes on the rapids and collet closing.I can feel the resistance change as the cams do their rapid approach and definitely feel the resistance change when there is a bar in the collet.
If you have moderate to heavy resistance all the time perhaps one of the cam shaft bushings is galled up or otherwise too tight. If so that may have caused the clutch problem. Check the free play in each shaft by trying to turn each back and forth by hand. You should be able to feel and hear the free play in the gear train.

If it is easier to turn the feed handle hand with the spindle turning that would indicate the feed clutch is dragging and giving assist when the spindle is on, another problem. Disassembling and cleaning the clutch may fix this also.
Even if the clutch is toast and no parts were available you could make the feed direct and power the feed with a small DC motor. The cost to do something like that would be minimal and add no expense to running the machine.
I did look for the A25 clutch mechanism over here only found some other things I have been looking for for years.

Thanks, Fred, and I will update as I dig into the machine.

Just to clarify minimal turning effort, I can turn it through easily with one finger on the handle, almost needs 2 fingers when the cross slide cam starts.
Your machine did not have water soluble coolant when you got it? If so you may be disassembling most of the machine and cleaning it out. I had to do that on this A42. It has had nothing but dinosaur oil in it since. (Mobilmet Nu and an Mobilmet 427)

Fred,
Problem identified and solved. I removed the clutch mechanism and opened up the rear of the machine to view the worm gear...no issues(I expected a chewed gear assembly...the kiss of death). I had earlier backed off all of the cam operations for the four slides...save the tailstock. The mechanism there was out of position and jammed into place, allowing only a few turns of the clutch mechanism before locking up. freed the cam drive on the shaft and everything smooth now. Thanks again for your help. On another note, do you have a spare feed tube and follower you might sell? I will be making one shortly, otherwise.

Glad it was easy. These old Traubs are almost bullet proof. I am attaching a photo of part of the feed mechanism that I have from an A25. If interested you pay the freight and it is yours, note the outside stand and tube are missing. If you will take it I can include all the A25 stuff I am sure I will not use (it will cost a little more freight). I posted some photos of a shop made bar feed based on a A42 bar feeder. http://www.practicalmachinist.com/vb/cnc-machining/options-bar-feed-retrofit-279639/
I can also post photos of the original A42 as well as others if you want to copy something else.


If you

Hi Guys, I`m new to here, but just checked up this forum on Traub lathes. I`m Richard

Hi guys, I ran Traub A25`s and other auto lathes for 9 years, now 15 years ago and have just brought 2 old A25 Traubs. One looks like I can get it going quite easily, the other a bit sad. They both have no bar feed, but have the weight stand, shut off switch and one has a good follower.
So I have to make a new bar feed which I have done years ago. Its not to hard bar will take a couple of days I suppose. The hardest part is milling a 3mm wide slot done the length of heavy wall tube. If you need some ideas or help I`ll keep you posted.
Another few set-up problems, I remember, if you find it hard to wind the cycle over by hand are -
- the Collet chuck clamping adjustment is done up to tight
- a cam follower is trying to climb up onto the cam to quickly, or is not set properly
- if you have a dead stop adjuster on any of the slides that is bottoming out to hard, this doesn`t help.

I used to make my own cams from mild steel, turning up and parting-off discs in a centre lathe, then case hardening then with a USA product called Kasenit, but we have been unable to get this in New Zealand for years now. I`ll probably use 01 Gauge plate or high tensile 4140 steel if I need to and flame hardeden the cam faces.
If you have any questions on production set-ups let me know I may be able to help, I previously made 100,000`s of components on Traubs including internal and external threaded part on a Traub with a rock-over threading attachment. Unfortunately I cat find one, even from the UK, where you can still get spare parts for Traubs.
Regards Richard

TMGURU,
If you are not too far along on your bar feed look at the one I made here:
http://www.practicalmachinist.com/vb/cnc-machining/options-bar-feed-retrofit-279639
If you are committed to slotting the tube you may want to use a slotting/slitting saw instead of an end mill.
Making a shop made rock over attachment for a Traub would not be impossible if you can not find one. I made a 2 position dove tailed slide for a Traub copy that overhead guide bars. I used it to drill and thread with a die head. I could post photos of that attachment or more photos of the bar feed if you like the idea.

Contacts

Hello,
Do you work with these types of equipment, Traub Type A25 Automatic Lathe? Because we have a branch here in the USA and we sell spare parts for this type of equipment.
If so, could you give me the companies you work for so we can get in touch?

Awaiting return,
Thank you.

cristianomm said:

Hello,
Do you work with these types of equipment, Traub Type A25 Automatic Lathe? Because we have a branch here in the USA and we sell spare parts for this type of equipment.
If so, could you give me the companies you work for so we can get in touch?

Awaiting return,
Thank you.

Click to expand...

Generally spamming on old posts is frowned on this forum. That said if you have parts that are difficult to find and can help members keep the old machines cranking out parts it may be tolerated.
This forum has a section where you can purchase advertising, you might want to look into that.
I do have an A42 Traub that needs nothing now, but may in the future. If you want to send me a PM with contact info I will put in on file.

well now i am looking for a manual for the Traub 15-20-25,