1958 Deckel FP2

[DennisCA]

Update, I have been working on this problem now for nearly three months.... Though I did take a break from the problem for weeks because I just had to....

I have made pushers to try and push it out but they did not work, the 3rd gear was just stuck too hard on the shaft. As the key got cut, it tore up the shaft and created radial grooves that locked it in place.

I have tried all kinds of things but last night I finally got the 3rd gear to move axially. The trick that worked was to use lapping paste (special non embedding paste) and rotate the shaft while holding the gear in place ad pushing it forward. This was a very slow and tedious process but it was what finally yielded results along with the latest pusher I made. I have now gotten the first gear off the shaft though I cannot get it out. I'm still working on the problem, things are kinda stuck again but I am hopeful I can get things moving eventually. I might have to rebuild the pusher again to get all the way there. The shaft is definitely damaged and will need repairs. Remains to be seen what that will entail.

 

[Carl Wilson]

Keep persevering, you will get it done of that I am sure. Great and inspiring work. You are helping keep me on track in doing my own mill restoration!

Your project - the pushers you have made to aid solving this problem - all brilliantly demonstrates the lengths that are gone to and the ingenuity exercised to get these old machines back in good order.

 

[DennisCA]

Success, the shaft is now out! But the first gear is still inside, as is the big gear in the middle, there is not enough room to get them out without disassembling the lower shaft. I think I will need to do this anyway, just to clean out the gearbox and bearings, I did a lot of grinding and things might need s proper cleaning, hopefully though there is nothing wrong with the lower shaft.....

The gears themselves looks almost completely unharmed, there is a burr on one of them but otherwise they all look fine.

Here are some pictures of the shaft, as you can see it's plenty damaged, the threads on the front are completely obliterated. So now, time to consider repair options? Maybe I'll just give it to a machine shop and ask them.

 

[Carl Wilson]

Are you able to make a new shaft? Is that a possibility?

 

[DennisCA]

I can pay a machine shop to do it, but the splines are an expensive operation. Which is why I am considering repair options. Or remaking just the damaged part and saving the splines.

 

[Seadog]

The splines shouldn't be that expensive to machine. They could be done on a horizontal mill quite easily. It does look like it's been heat treated, particularly around the splines.

 

[Carl Wilson]

Forgive my ignorance. Would the splined portion be case hardened?

 

[DennisCA]

I'm not sure they are heat treated or case hardened, haven't tested yet. But all the surfaces are finish ground at least. I've put all the major dimensions into CAD now, still more modeling to go but I got the basics.

 

[eLuSiVeMiTe]

I'm not sure they are heat treated or case hardened, haven't tested yet. But all the surfaces are finish ground at least. I've put all the major dimensions into CAD now, still more modeling to go but I got the basics.

Wouldnt turning the damaged portion down and making a sleeve to rebuild the damaged parts be an option ?

 

[DennisCA]

I thought of that but how deep would you need to go, to the bottom of the key slot? And how it would it be fastened?

 

[Carl Wilson]

So turn down the portion with the keyway, make a sleeve then press that on. Then finish turn between centres to ensure concentricity of the sleeve with the shaft. Then mill the keyway? Presumably one could part off the damaged threaded piece then thread a suitable bit of stock and insert it in a similar way?

 

[eLuSiVeMiTe]

I thought of that but how deep would you need to go, to the bottom of the key slot? And how it would it be fastened?

Heat the new and freeze the old for a fixed fit.

I'd want a bit of meat underneath the keyway.

 

[Carl Wilson]

I see now that the keyway depth seems to go right down to where the threaded portion starts.

I thought that also, the sleeve would be an interference fit and shrunk on.

The sleeve could be made to incorporate a reduced diameter at the end. When shrunk on and finish turned this reduced diameter could be screw cut for the thread.

 

[DennisCA]

Yes that's something I noticed as well. I am not sure I trust an interference fit in this application. I also cannot turn between centers anymore as the front is ruined.

I do think it would be more feasible to cut the bit off before the bearing surface because of these issues, I have a fixed steady rest for my lathe to keep things aligned. Then drill and tap and fit an oversize bit that can then be center drilled, then I can turn that between centers.

 

[Seadog]

The problem with a sleeve is that the keyway runs for virtually the entire length, so the sleeve will be, in effect, just a piece of steel wrapped arond the shaft. If it was individual key seats then I'd agree with a shrink-fitted sleeve, but it seems to be a bit of a bodge in this case.

Using a fixed steady it should be easy to centre the shaft and then face and recut a centre.

 

[DennisCA]

Right well I don't think a sleeve would work in this instance.

Continued on the CAD model and made a drawing with the main dimensions, the relief cuts I did not detail because I believe they are non-critical, mainly for making sure oil gets in there and lubricates the setup I believe, it's a 45 degree cone though that is around 1mm deep and 2mm wide.

Repair options I have considered / been offered by others:

1. Part the shaft where it reduces to 27mm, bore a hole and tap it, say M20x1mm LH thread (LH required for a self-tightening thread). Fit an oversize blank onto the shaft, red loctite and machine new features.

2. Part the shaft and remove only the M16x1 thread, bore & tap a hole like in option 1 and remake the threaded portion. Turn the shaft only to clean up the burrs, so the gears will fit again. Machine a new slot opposite the old one and use that instead, leaving the old slot as is.

3. Turn down everything 27mm and below for a clean face and weld on material and machine new features. Perhaps a local shop might do spray welding, though that won't be enough to fill up the old slot, but it might not be required either to do a repair.

 

[Robbair]

Option 3 seems to be the neatest, .... even if the chosen technique didn't 100% sort the slot, you still have the option to recut the other side?

 

[DennisCA]

Well a machinist on the PM forums in California has offered to make me a new shaft if I send him the original and spline gears for fitting, I think maybe that is the best solution. I've seen his work and he is good at what he does and a Deckel user and expert.

 

[Carl Wilson]

Seems like a very good option.

 

[DennisCA]

This weekend I removed the entire lower shaft. It goes out the front and not the back.

The lower shaft components all look to be in fine shape except the front bearing I should probably replace it, it feels worn and the bearing at the rear had some kind of cover that has been destroyed somehow. Now I can properly clean out the entire gearbox. It's for the best to take it apart I can tell, my working on the upper shaft had left all kinds of debris on the lower components and bearings, would not have been good for the components to leave it as is.