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Soft Jaws

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Bill Dawes28/08/2010 19:44:16
539 forum posts
Hi all, does anyone know if I am likely to find a source of supply for soft jaws for a 3 jaw chuck I have. It is a 5" and bears the name 'Baige', Chinese made I think and supplied by Machine Mart but they are unable to help.
Bill D.
Martin W29/08/2010 00:14:40
921 forum posts
30 photos
Bill
 
Both Chester and Warco do soft jaws for 130mm 3 jaw chucks of Chinese origin. Usual disclaimers apply.
 
Cheers
 
Martin
Ian S C29/08/2010 12:09:22
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7468 forum posts
230 photos
Is it possible to diy soft jaws on the lathe, ie cut the spiral thread. he rest is easy.Ian S C
John Stevenson29/08/2010 12:27:38
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Moderator
5068 forum posts
3 photos
No Ian,
The 'thread' on the back of jaws isn't a spiral because the diameter of the scroll changes towards the outside, i.e. get bigger - larger radius.
 
To get by this each tooth is boat shaped.
Add to this the tooth form isn't central on the jaw but offset to one side. I did read up on this in a very good article in MEW, around #155 - 120 I think on why they were like this and how to set out jaws.
 
John S.
Gordon W29/08/2010 16:36:36
2011 forum posts
I've thought about buying a new set of jaws for my cheapo chuck, they arn't to dear. Then welding, or bolting, mild steel to the old jaws. Any ideas?
John Stevenson29/08/2010 22:44:23
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Moderator
5068 forum posts
3 photos
Gordon,
I use soft jaws quite a bit, not so much for production where they are mostly used but for special applications.
 
A while ago I made a set up to hold thin items such as washers and small gear blanks. Because you either need a lot of special jaws or continually having to remachine them I came up with loose jaws on top of soft jaws.
 

These consisted of three hexagonal blocks bolted to a set of plain soft jaws.
this pic shows better the build up.
 

A set of soft jaws had a tenon machined on and then all at the same setting with all three held in a vise on the mill the counter-bored holes and threads were put in so they were all in line.
 
Each hex piece had  three slots machined in to match the tenon and a spigot pressed in to match the counterbore.
 
This gives you 6 corners to machine away and three different diameters to work at depending on which hole.
I numbered the jaws and I keep a list of regular jobs / diameters with the jaw number and bolt position.
 
John S.
Ian S C30/08/2010 01:17:18
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7468 forum posts
230 photos
John S, I understand that the jaws would have to be mounted on say a face plate 120deg apart, and extra clearance in form of a curve on the outer dia of the teeth, and a liitle less on the inside, yes could be a little difficult. Ian S C
Gordon W30/08/2010 10:17:27
2011 forum posts
Thanks for that John, but all I get for the photos is a "no entry" sign, I think I understand tho'. Maybe wasn't clear in orig. posting, I intend to use the old hardened jaws and weld on soft mild steel, soft jaws not being on sale for my cheapy chuck.
Martin W30/08/2010 11:07:25
921 forum posts
30 photos
Hi
 
There is a good article on making soft jaws by Harold Hall in MEW volumes 145 & 146. Not only does it cover general use of soft jaws, specialised bolt on attachments  including hexagonal attachments but also  making soft jaws from scratch with instructions on how to cut the tooth form to engage with the scroll on the chuck.
 
Though I haven't tried to make soft jaws from scratch I did find the article informative and useful.
 
Cheers
 
 
Martin  
John Stevenson30/08/2010 23:36:16
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Moderator
5068 forum posts
3 photos
Gordon,
Photo link repaired.
 
I did a search and found the original article I was thinking off, it's in #116 by Ken Thornton.
A different method to Harold Halls method but a bit simpler.
 
John S.
Martin W30/08/2010 23:42:18
921 forum posts
30 photos
Hi John
 
That's a neat solution.
 
Cheers
 
Martin

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