Chuck jaws

This topic has 18 replies, 11 voices, and was last updated 24 June 2014 at 19:24 by nousername70901.

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4 January 2011 at 11:36 #61732
macmarch
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@macmarch
Happy new year to all.

Having determined that I cannot get a set of soft jaws for a chuck I want to know if the material used hardened and tempered through or case hardened. Either way can I heat and anneal them done to the point where I can machine the tops off and drill 2 holes in to clamp soft blocks onto them?

ray
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4 January 2011 at 11:36 #5346
macmarch
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@macmarch
4 January 2011 at 19:06 #61747
John Olsen
Participant
@johnolsen79199
I wonder if one of those drills that will go through a file would be able to tackle them? Then to remove the tops you could just grind the jaw. Or maybe you could grind off the top, and then just braze the soft piece on. This would probably spoil the temper of the jaw, but of course that does not matter, and it does not matter if it stays hard either. The other way that occurs to me for making holes in hard material would be spark erosion.

regards

John
4 January 2011 at 19:21 #61749
macmarch
Participant
@macmarch
Thank you John,

I have a set of these drills that I use for drilling spanners. I’ll give them a try.

Do to the nature of what I will be using them for I need to be able to achieve a flat surface to clamp the ‘soft’ jaws to. I use external and internal jaws. The main problem will be to tap the holes!

cheers

Ray
4 January 2011 at 19:27 #61750
Tony Pratt 1
Participant
@tonypratt1
Hi Ray, I should imagine they are mild steel case hardened purely on the cost involved in using a “better” type of steel but I stand to be corrected. If case hardened, a carbide drill should go through say 2mm deep into the soft steel and you will have no trouble tapping it, use a drill slightly larger than the thread O/D

Tony
4 January 2011 at 20:06 #61751
Ramon Wilson
Participant
@ramonwilson3
Ray,

I would think they are in all probability case hardened. Unless you need to keep them as they are at present could you get the ‘nose’ of the jaws ground down to the level of the next step. That way you could then drill and tap the core and have a longer surface upon which to mount the soft jaw.

The big paradox is bring yourself to grind the jaws to find out.

I would be interested as I’m sure others would in hearing how you get on – I have a ‘new’ used chuck bought his year with no soft jaws either

Regards – Ramon
4 January 2011 at 20:10 #61752
JasonB
Moderator
@jasonb
I should think a lot will also depend on the quality of the chuck, its likely to be easier going with a cheap far eastern item than a quality Pratt Burned or similar.

If its a big chuck you may be able to get away with counter boring your holes from the back for cap head screws and tapping the soft jaw blocks without loosing too much of the teeth. Possibly plunge cutting with a carbide endmill.

Jason
4 January 2011 at 20:40 #61756
Brian in OZ
Participant
@brianinoz24148
Hello Ray,

Just a thought, why “modify” a perfectly good set of jaws on/in your chuck, how about fabricate a set of “shoes” for the jaws out of the soft material, then just super glue them on or maybe use some Selastic to hold them on temporarily. When the job (requiring the soft jaws) is finished, take them off and stash away for next time, leaving your chuck jaws untouched.

Brian (in sunny ?? OZ)
4 January 2011 at 20:45 #61757
V8Eng
Participant
@v8eng
Issue 166 of MEW had a couple of articles on making / using soft jaws.

Sorry this is short on detail, but I cannot get to my previous issues at present.
4 January 2011 at 21:10 #61765
macmarch
Participant
@macmarch
Wow, lots of ideas. Thank you all.

The chuck in question is a brand new 5C 3 jaw. I will take one jaw to the grinder. If case hardened then I’ll give a good blast with the oxy. Also just looked at Harold Halls article in MEW 146. I’m tempted to have a go and make a set or two. Has anyone done it?

Whatever happens I’ll post the results.

cheers

Ray
5 January 2011 at 11:33 #61782
MICHAEL WILLIAMS
Participant
@michaelwilliams41215
Clamp the soft jaws to unmodified existing chuck jaws . Make your soft jaws to look something like hexagon nuts with the hole through tightish fit on existing chuck jaw smallest diameter steps . Arrange clamping screw(s) to come in radially and lock on the outside of the chuck jaws .
5 January 2011 at 13:53 #61788
John Stevenson 1
Participant
@johnstevenson1
Ray,

Yes they will anneal.

I have done quite a few sets PB, TOS etc and not come across one set that hasn’t annealed.

John S.
5 January 2011 at 14:24 #61790
Gone Away
Participant
@goneaway
What would be the simplest way to anneal them … for someone without any sensible equipment. Could they be, for example, heated on the rings of an electric stove?
5 January 2011 at 17:38 #61800
macmarch
Participant
@macmarch
Well I’ve checked the jaws and they are indeed hard, in fact a deep grind at the back shows that they are H & T through. I must asume the spec is something like EN8 ,16 or 24T. The drills I have that will cope with spanners etc don’t even look at them.

Tomorrow morning I’ll give them a good soak in the oxy and go from there.

The article by Harold Hall makes very interesting reading. I don’t need the jaws to have full form teeth. I will only be holding light section Aluminium discs so no great clamping power needed. Therefore even though I will anneal the jaws I will also make a set but use H & T silver steel pins as the teeth.

Again thank you for all your help so far and I will put up pics of the final result.

Sid, Apart from oxy any decent propane burner with a reasonably large burner will do the job. Just remember that the heat treatment will have been done in an oven. Heat to dull cherry, (its not the temp yopu require), and hold it there for a good 5 minutes, 10 would be better. Then bury the part in dry sand. You need to get the cooling to take as long as possible. Its all to do with grain recrystalisation. This is why when you have hardened silver steel and then proceed to temper, It as best to put the part in the oven. This will allow time for the grain structure to change correctly. Also there is no panic to dunk the part as the colours run. You can watch the parts change colour slowly.

cheers

Ray
5 January 2011 at 19:05 #61815
Ramon Wilson
Participant
@ramonwilson3
Ray, just an aside to that – one of the best heat retainers for stress relieving I’ve found is spent ash – sand is okay especially if heated first before putting the part in but ash will hold the temp longer

You just need someone with a coal fire! All those loco owners?

Regards – Ramon
5 January 2011 at 20:07 #61818
macmarch
Participant
@macmarch
Forgot about ash. Used to use it back when I was an apprentice. we had plentiful supplies from the old pot bellied stove in the workshop.

ray
7 January 2011 at 18:15 #61943
macmarch
Participant
@macmarch
Success! Gave them a good going over with the oxy and buried them in preheated sand, (haven’t got a coal fire) The bandsaw took the unwanted bits off. Drilled and tapped then fitted 1″ x 2″ x 1/2″ steel ‘soft’ jaws. Job done.

Just goes to show that you learn something everyday, 50 years in engineering and didn’t realise that you can soften hard jaws.

cheers

Ray
7 January 2011 at 18:54 #61949
Ramon Wilson
Participant
@ramonwilson3
That ‘s great to hear Ray, soft jaws are so useful.

Mine are on a second life using hexagonal additions but the new chuck will need something at sometime.

It’s also what makes this site so great too eh

Regards – Ramon
24 June 2014 at 19:24 #156188
nousername70901
Participant
@nousername70901
Nothing to do with modifying chuck jaws. Does any one know how to true a set of hard jaws. My three jaw chuck is slightly out of true on one jaw and seem to grip at the back before the front. I think I saw an articale on this subject in a model magazine some where but can not remember where.Pete
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