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Broken ML7 tailstock handwheel! Help!

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Andrew Tinsley29/12/2016 16:14:24
577 forum posts

I seem to be monopolising the beginners section, so apologies for another post!

I was cleaning up my tailstock this afternoon (ML7) and the handwheel parted company from its boss! Further inspection revealed that it had been glued together with some form of cyano! The breaks are in the centre of each of the three "spokes".

Now tailstock handwheels seem to be quite rare on Ebay (you have to buy a complete tailstock to get the wheel). So a replacement isn't going to be easy to source unless I buy the complete tailstock.

Any idea of how I could repair the handwheel. I suppose I could clean up the breaks and use some form of Loctite, but I am not sure how long this would last. I am baffled as to how to do a mechanical repair, the spokes are quite thin and flat and don't seem to lend themselves to an easy repair method

Thanks in advance,

Andrew.

Swarf, Mostly!29/12/2016 16:39:48
400 forum posts
37 photos

Andrew,

You have a PM.

Best regards,

Swarf, Mostly!

Chris Evans 629/12/2016 17:16:38
997 forum posts

Look up WDS standard parts on the net. Most likely something standard can be made to fit.

Jeff Dayman29/12/2016 19:03:52
1067 forum posts
23 photos

Andrew - As Chris mentioned there is likely a standard handwheel available from tooling component suppliers close to the size needed that could likely be adapted. MSC, McMaster Carr, Jergens, etc in North America all carry many sizes in several materials.

If the broken one is cast iron, why not grind the broken edges to make a V shaped groove at each break, and bronze weld the breaks? You may need to make a simple fixture to hold the parts in alignment during bronze welding. A plate to bolt the hub to, spacers for the rim, and hold- down clamps of some kind to hold the rim to the spacers would do, preferably in rusty steel so the bronze won't stick to the fixture as easily, should it flow onto it. If you have not got access to oxyacetylene equipment you could try silver solder with a Sievert or equivalent torch, well cleaned joints and plenty of good flux. Or take the item to a machine repair or agricultural repair shop and ask them to do it.

If you were 3000 miles closer you could drop by here (Waterloo Ontario Canada) and I could do it / show you how. Not a complex fix at all with bronze welding and as strong as the parent metal usually.

Good luck JD

MalcB29/12/2016 19:32:00
224 forum posts
27 photos

Theres a Myford Handwheel on Ebay now with a £30 BIN. Also RDG part of Myford stock a range of various handwheels which one of which may be modified to suit

Andrew Tinsley29/12/2016 20:12:00
577 forum posts

Thanks for the suggestions so far, I am taken aback at the bronze welding suggestion. I do indeed have oxyacetylene and I have done a great deal of silver soldering and Sif Bronze "welding". I have always thought that cast iron was virtually unweldable by any method, let alone Sif Bronze!

I have seen references to mig welding of cast iron which had a lot of caveats, which I take to be an unreliable method. I will certainly give Bronze "welding" a try, although I am a bit of a doubting Thomas!! But then again I am always amazed at my lack of knowledge in these matters! That is why I keep asking questions in the Beginners Forum.

Andrew.

David Standing 129/12/2016 21:45:15
679 forum posts
38 photos
Posted by Andrew Tinsley on 29/12/2016 20:12:00:

I have always thought that cast iron was virtually unweldable by any method

I have seen references to mig welding of cast iron which had a lot of caveats, which I take to be an unreliable method.

Andrew.

 

Andrew

I did, many years ago, successfully stick arc weld (cold!) a cracked cast iron car exhaust manifold, but I wouldn't recommend it wink 2.

Edited By David Standing 1 on 29/12/2016 21:45:48

Jeff Dayman29/12/2016 22:19:55
1067 forum posts
23 photos

"I have always thought that cast iron was virtually unweldable by any method, let alone Sif Bronze!"

 
No, CI is very repairable with bronze welding. I do repairs that way regularly on CI items, as did my father and grandfather before me, who taught me how to do it. (They were small town car and agricultural repair professional mechanics and worked on everything mechanical. )
 
Vee out the joint , get everything clean with grinding or at least a stainless steel or steel wire brush, heat both sides to dull red heat before applying bronze. Use the flame to "wash" a bit of flux onto the joint off the rod. Continue heating until the bronze starts to run and fill the joint. If the bronze starts balling up, or you get a pocket that won't fill over or fill evenly, it's likely dirty. Clean it up by a bit of grinding and try again. Everything from car manifolds, engine blocks/heads with freezing damage to pumps, handles, impellers, machine parts, and tooling components in cast iron can be repaired this way. Welding cast iron with any electric welding method is more difficult and riskier than bronze welding, because the joint is brought to heat more gently by oxyacetylene heating, reducing internal stresses, and because the process is not as hot as electric welding, there is virtually no carbon migration to the weld puddle boundary. This is a major issue with welding cast iron electrically, and is dependant on the metallurgy of the CI of the original parts as well as preheat , current/weld heat and type of rod used in the welding ops. I have seen many electric welds in CI parts fail where the new weld and original broken portion of the part just pulls away from parent metal and you can clearly see a zero strength soft carbon layer at the break. Electric welding CI certainly can be done, and I have done it for applications with parts operating at very high heat, but generally bronze welding is far less risky for applications operating with lower heat or no heat. To fix such failed electric welds the carbon can usually be ground out and the joint bronze welded as usual.
 
I know for a fact that literally hundreds of bronze welds on CI I did as long as 30 years ago to recently are still in service in many types of machines with no problems at all. I have several in my workshop downstairs, too.
 
(Do note though for extreme heat applications in CI , ie operating at red heat, like in diesel engine cylinder head valve seat repairs, bronze welding is not the best choice.)
 
Good luck with your handle. JD
Andrew Tinsley29/12/2016 23:10:21
577 forum posts

Thanks Jeff for your time and trouble in outlining the technique required. It seems straightforward enough and I will give it a go in the morning!

So another one of my long held believes bites the dust!

Andrew.

Hopper29/12/2016 23:28:43
avatar
2038 forum posts
23 photos

I have a six-inch bench vice that before my ownership was broken in half, god knows how, and then bronzed back together. So far it has taken years of punishment without failing. So I imagine bronze should work fine on a handwheel.

They do come up on eBay regularly. Maybe just quiet right now due to the holidays, or being too cold out in the shed. Many of the model engineer suppliers beside RDG stock them too.

not done it yet30/12/2016 00:43:27
1221 forum posts
9 photos

Looking at pics, I think I would likely clean off the cyano, glue it with loctite, support it rigidly, drill and tap across the cracks and loctite in three screws. Clean it up and it should be as good as new?

Edited By not done it yet on 30/12/2016 00:44:03

Bandersnatch30/12/2016 01:23:09
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898 forum posts
36 photos
Posted by Hopper on 29/12/2016 23:28:43:

They do come up on eBay regularly. Maybe just quiet right now due to the holidays, or being too cold out in the shed. Many of the model engineer suppliers beside RDG stock them too.



Just an observation: the OP stated that his was an ML7 part whereas, as far as I could see the one(s) in the link above were all S7 parts. The complete tailstock assemblies are afaik interchangeable at that level, but not the handwheels.

When I broke a handwheel on a rusted-up tailstock from an ML7 I was restoring, I followed eBay for 6-9 months without seeing an ML7 one. In fact the only one I found was with a chap (private individual) in the UK who wanted £34 (in 2009) but would only ship to Canada by a premium courier service for a cost of £50. I would have been fine with basic mail with or without insurance but to no avail. He refused to ship any other way (nice of him to be so cavalier with my money). So I declined.

I'd also tried the the usual culprits at that time .... Myford (the original) had some (they did eventually respond) but at extremely Myford prices. RDG, Chronos and the others didn't.

Mine had broken in the main boss, not the spokes as the OP's one was, and in the end I was able to machine it back and make a shrink-fit +loctite insert which I viewed as a temporary solution until a suitable part became available. In fact it's lasted fine now for 6+ years and is essentially invisible so I gave up looking.

Swarf, Mostly!30/12/2016 09:21:05
400 forum posts
37 photos

Andrew,

My Private Message (aka 'PM' ) to you is still showing as 'unread'. I suggest that you log in and click on the 'inbox' icon in the green bar at the top of the screen.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 30/12/2016 09:21:42

Nicholas Farr30/12/2016 10:37:54
avatar
1603 forum posts
822 photos

Hi, stick welding of most grey cast iron is not that difficult to weld with the correct electrode. I used to have to weld some fairly heavy parts during my old maintenance job at times. This **LINK** is the last cast iron part that I welded using nickel-iron electrodes that were designed for the cold welding of cast iron. You still need heat, but it is relatively cold compared to brazing or gas welding. The biggest problem you find though, is not the welding, but the cooling down period, when the part is most likely to fail by cracking beside the weld or in some other place, this is largely overcome by correct pre-heating and maybe post-heating and allowing the whole job being allowed to cool slowly. My job was left amongst some warm refractory bricks to cool down, but hot ashes from a fire or hot sand are both effective.

Regards Nick.

P.S. This may interest you http://www.castolin.com/en-US/product/eutectrode-244 some info on the welding procedure in the download.

Edited By Nicholas Farr on 30/12/2016 10:54:40

Martin Cargill30/12/2016 11:11:13
52 forum posts

We come across this from time to time when reconditioning machines. One method we use is to find another similar handwheel with a larger centre section and bore it out. Then take your broken handwheel and turn the outside until it will fit the inside of the new one. This can be an interference fit (fit it by heating the outer and freezing the inner) or it can be fitted with Loctite or Araldite. Screws or pins can also be used but as this is not a safety critical component they are probably overkill.

Martin

Andrew Tinsley30/12/2016 13:26:23
577 forum posts

Thanks everyone, so far the Ebay lead turned up something entitled ML7 tailstock handwheel, but it most certainly wasn't one from the picture that was there!

Hello Swarf! I did read the email from you (It was your well written profile!) I did reply. Is there another PM from you? If so it hasn't arrived yet!

Thanks again everyone,

Andrew.

P.S. I am off to try Sif Bronze "welding" on the beast!

Swarf, Mostly!30/12/2016 13:48:16
400 forum posts
37 photos

Hi there, Andrew,

The member's profile is different from a PM, it is accessible to all - a PM is only accessible to the addressee (and maybe to moderators).

I say again, look in your inbox, accessible by clicking on the 'inbox' icon in the green bar at the top of the page (you need to be logged-in to do this).

Best regards,

Swarf, Mostly!

Jeff Dayman30/12/2016 21:31:15
1067 forum posts
23 photos

How did the bronze welding effort go Andrew?

Andrew Tinsley01/01/2017 19:49:47
577 forum posts

Hello Jeff,

The welding went very easily and seems to be well strong enough for the job, I am afraid the finished item isn't very pretty, difficult to get a file into the places that need most fettling! It didn't do the chrome finish on the wheel a lot of good either! Apart from those two downsides, I can recommend the use of bronze welding for CI. As I said before,. another of my fixed ideas going down the drain.

Thanks everyone for your help.

Andrew.

Jeff Dayman01/01/2017 21:27:27
1067 forum posts
23 photos

Hi Andrew,

Glad to hear you got a good structural bronze weld repair. I wouldn't worry much about making it it pretty if it works OK. For cleaning up the excess bronze you might try the small dia longish grinding wheels intended for sharpening chainsaws in a Dremel style electric die grinder. The cheapie Chinese die grinders are great for this - you can beat the hell of them and when they are done after a year or two, for the few dollars paid for them you can toss them without much remorse. The chainsaw grinding wheels are handy and the red-brown soft grinding wheels are also, the ones about 1/2" diameter. HSS cutters for the Dremel style tool will also deal with bronze but are harder to control - they tend to dig in and groove out one spot.

Might be wise to give the welded areas a lick of grey primer paint to keep rust down, I find recently welded items rust quickly of course because all the oil and paint gets burned off.

Do check your chromed areas for any loose flakes where you were welding, and remove them - they can cause nasty cuts. Personally I don't like chrome anywhere on tools for just this reason, much rather have painted or plain polished / oil finish CI where my hands contact the controls. Luckily on my ancient SouthBend lathe and mid - 1980's Taiwan made mill there is no chrome to be worried about.

Cheers and Happy New Year to all JD

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