Wadkin AGS10 Spindle repair, hit a brick wall, help

[deema]

I have a Wadkin AGS10 spindle that needs a lot of TLC. The two bearing journals are worn, in fact the rear journal is worn so badly its actually now a hollow in the spindle. Now, if I had the skill to cut square threads, which I believe the saw nut has, I would simply make a new one. However, I struggle with ACME and know I haven’t a hope of a true square thread! So, can anyone think of a solution to repair the spindle. Things I’ve considered
1. flame spraying metal to rebuild the surface. Don’t have the kit, and probably prohibitively expensive to get it done.
2. sleeve the journals with a shrink fit / silver solder / braze and then machine them up. The rear journal is too worn to allow this, ie its too small already to machine the surface clean and allow a shrink fit.
3. weld it up with the MIG and then machine. Probably distort the shaft?

anyone any other suggestions??

Thanks in advance.

 

[TFrench]

For the effort it could save, do some trial pieces to see if you can find a good recipe for cutting square threads. I've done that recently for knurling, just keep erasing it till you've got it cracked or the bit of scrap is too small!
I have got a flame spray setup but I haven't used it yet - I'm not convinced it's really safe where my lathe is - you're meant to have good extraction and that's one thing I'm completely lacking. I do know a guy down in Essex who is setup for it and would probably be happy to do it for you if you want me to ask?

 

[deema]

Cheers TFrench,
The spindle threading doesn’t have a run out / starting gutter, it’s left hand and I’m not sure how it was originally done, perhaps rolled or a die head to a stop. That’s another way of saying I don’t know how to start the thread / increase the cut depth without a gutter. If I had a CNC it would be relatively easy…..but alas, I don't…..always another tool to get

The thread start is exactly where the blade will sit, so, it has to be right and without a gutter. If you can think of a way of single point cutting it, I’d appreciate it.

I appreciate the offer of help, I will message you.

 

[TFrench]

I see your point!

 

[heimlaga]

I have repaired a spindle by stick welding once. If I remember correctly I used some special soft welding rod intended to be easy to machine. I managed to straighten it and to file the built up surface round and to the proper dimension within 0,05mm.
The problem was that there remained internal stresses within the material and over 10 years time the spindle got more and more bent until I had to bite the bullet and replace it.
Looking back I should have had the spindle professionally annealed after repairing. However the annealing heat and oxidation would have affected the fit of the bearings so this would not have been a good ideaafter all.

In this case I rekon you should ask a local machinist to turn a new spindle for you from new material. Maybe the flange could be pressed off and reused?

 

[Inspector]

Cheers TFrench,
The spindle threading doesn’t have a run out / starting gutter, it’s left hand and I’m not sure how it was originally done, perhaps rolled or a die head to a stop. That’s another way of saying I don’t know how to start the thread / increase the cut depth without a gutter. If I had a CNC it would be relatively easy…..but alas, I don't…..always another tool to get

The thread start is exactly where the blade will sit, so, it has to be right and without a gutter. If you can think of a way of single point cutting it, I’d appreciate it.
View attachment 126448

I appreciate the offer of help, I will message you.

There was a thread in the Aussie Metalwork Forum about tool holders that automatically retracted when the lathe was reversed. It would be the ticket for you if you can flick it into reverse. The tricky part is having a lathe that can be reversed on the fly. Another option would be a holder that pulled out the insert when it hits a stop on the bed. There are all kinds of carbide inserts for square section and Acme threads. In your line of restoration they would be handy to have.
Maybe it will help.
Pete

 

[Cabinetman]

Sorry Deema no help coming from me, just wanted to say that if you can’t fix it I don’t think anybody bloody well can!

 

[Sideways]

Here's an approach - just brainstorming but maybe something among these steps will spark another idea ?
Machine a new piece, including the flange whether integral or silver soldered / brazed in place.
Possibly try for some stress relief after if you "braze" by re-heating the whole thing with a torch to a lower temp and allowing to cool in a heap of sand. (I don' know how hot you need to get for this to do any good BTW, but it's something that could be done on a small scale.
You could then put the spindle back on the lathe and machine it to finished dimensions and square the flange.
Leave the shaft plain where the blade will sit on it. Cut a long LH thread with as small a gutter as you can outboard of that.
Turning a LH thread could be done if you can get your toolpost out to the far side of the work and spin the lathe in reverse but feed still towards the chuck. Yes ? Tool would be the normal way up, pointing back towards you, but needs a LH insert I guess.
When you make your nut, counter bore the inside of the nut just enough to clear the gutter and clamp down firmly on the blade. A little tolerance here will be needed to allow for thin and thicker blades. If your nut is a little thicker than normal to ensure you still have a good length of thread engaged, that probably won't affect the saw.

There's a fair bit of work in this isn't there. Must be a better way !

 

[hennebury]

I rebuild a lot of machines with worn shafts. have made a few shafts and flame sprayed a few, but you can also order shafts cut to size and threaded, I think that may be your best bet. I am sure that you could find a company to supply them online. Flame spray is not that expensive to get set up, if you plan on doing a few more. I would rather make new shafts rather than repair if it was feasible. Not sure on how to do that thread, I haven't done any like that, I like the idea of a gutter and a counterbore in the nut.

 

[clogs]

thats an easy repair really...I'd def keep away from heat....
If u get it hard chromed and centerless ground back to size as good as new....
prob cheaper tha getting a new shaft made....
look in the classified adds for old motorcycles....I'm sure there's a firm in Leighton Buzzard, Beds that do this all the time....they spcialise in the repair of irreplaceble headstock shafts on vintage bikes...
also they rechrome/repair ball races bearings as well....

 

[deema]

Not sure on how to do that thread, I haven't done any like that, I like the idea of a gutter and a counterbore in the nu

Thats a good idea, the downside would be that it would limit the blade thickness, preclude the use of a dado stack,
Really nice work, terrific result you have achieved on that shaft. I’m avoiding acetylene in the workshop, the insurers don’t seem keen! When I’ve watched the process, it also makes my knees shake, fearsome!

I’m going to contact a flame spray chap TFrench has kindly put me in contact with.

 

[deema]

If u get it hard chromed and centerless ground back to size as good as new....

Thanks for the suggestion, I’d not thought of hard chrome. I will have a look at what’s around. There us a fair build back needed.

 

[deema]

Turning a LH thread could be done if you can get your toolpost out to the far side of the work and spin the lathe in reverse but feed still towards the chuck. Yes ?

Cheers Sideways, your right, a LH thread can be turned towards the flange by moving the tool post to behind the part, however without some form of instant tool retractor as suggested by Inspector, at the end of the cut you create a gutter. I have removed the flange, and wondered about hiding the gutter underneath that. However its not very wide and I’d create a void right where the flange needs the most support to maintain its concentricit.

Somebody has been here before me, the inner land on the flange has been turned off, can’t think why it has been done. I’ve pointed at where you can see a witness of where it once was.

 

[deema]

Evidently, the bearings have been changed around 5 years ago. The bearing next to the flange was stuck, and the shaft was taken to a blacksmith who heated it up to white hot to removed the bearing. I’m wondering if it really needs stress relieving in case the heat cycle has created stresses? What do you think?

 

[clogs]

Deema.....there u go....
as for hard chrome.....
they will machine it to a leval surface and then rechrome the damaged area.....
it can be really quite thick...it's what is used on hydraulic cylinder rams for diggers etc....
same thing, they chrome up the rod then centerless grind them to size....
easy peasy.....
it used to be very expensive but it's now used alot in industry, hence cheaper....
just found the address.....
hope this helps.....

AM Philpot (Hard Chrome) Ltd
Unit D, Cradock Road Ind Estate
Luton, Bedfordshire
LU4 0JF
Tel: 01582 571234
24 Hour: 07831 276789
Fax: 01582 584924
[email protected]

 

[deema]

Clogs. Your a star, I will give them a shout.

 

[Inspector]

Evidently, the bearings have been changed around 5 years ago. The bearing next to the flange was stuck, and the shaft was taken to a blacksmith who heated it up to white hot to removed the bearing. I’m wondering if it really needs stress relieving in case the heat cycle has created stresses? What do you think?

Unless the blacksmith quenched it while hot or they used an exotic air hardening steel, which I doubt, it will be normalized (can't anneal ferrous metal) and already be soft, maybe softer than original. Getting it hardness checked, possibly by the hard chrome people, will tell you. If you have another similar shaft they can compare with would be better. If the original hardness isn't above HRC45 you should be able to cut a new thread in pre-hardened metal with an insert cutter assuming you can lick the left hand, square thread, fadeout challenges.

Pete

 

[deema]

Thanks everyone for all of your help and suggestions. For completeness, the quote for hard chrome and grind is £201.60 including VAT. The quote for flame spraying and machining the surfaces back up is £75 to £90 (not sure if this is exvat) depending how how much powder is used.

The spindle is for a chap, and depending on what he wants doing to it will determine what we will do next.

 

[TFrench]

The hard chrome quote is actually surprisingly reasonable.

 

[deema]

TFrench, totally agree, I was pleasantly surprised how reasonable the quotes are, a lot less than I’d anticipated.