Soft jaws

[steamdaveParticipant @steamdave]

Somewhere, sometime ago there was a description of how to make soft jaws for a 3 jaw chuck. The method used hex aluminium with holes bored through the centre to fit over each jaw projection and secured somehow to the jaws.

Does anyone remember the design and where I would be able to find it? A Google search doesn't bring up anything for me.

I have seen Harold Hall's design, but I don't want to drill the jaws of my Pratt Burnerd chuck.

Dave
The Emerald Isle

[steamdaveParticipant @steamdave]

[Clive Brown 1Participant @clivebrown1]

Not quite answering your question but I recently bought soft-jaws for a 5" PB 3-jaw chuck from Rotagrip. Quick delivery and cost abour £30 including postage.

[steamdaveParticipant @steamdave]

That's £30 too much for me Clive!

Dave
The Emerald Isle

[Thor 🇳🇴Participant @thor]

There is one solution at Mike's workshop, that may be of help. Another here.

Thor

Edited By Thor 🇳🇴 on 29/07/2022 11:08:38

[JasonBModerator @jasonb]

Just drill and tap a hole in from 3 corners of the hex stock so you can put a clamping screw in that bears on the back of the jaw., the three remaining corners are what you use to grip the work

[DC31kParticipant @dc31k]

There is another version here: https://www.cgtk.co.uk/metalwork/m250/hexsoftjaws and that references MEW 224.

[mike robinson 2Participant @mikerobinson2]

here you go

[steamdaveParticipant @steamdave]

Posted by DC31k on 29/07/2022 14:34:45:

There is another version here: https://www.cgtk.co.uk/metalwork/m250/hexsoftjaws and that references MEW 224.

That's it DC. Many thanks.

Also, your idea Mike was one I had seen before but had forgotten about.

Now to put some redundant ali hex to good use.

Dave
The Emerald Isle

[old martParticipant @oldmart]

I have bought several job lots of used soft jaws on ebay very cheaply. You have to take a risk that they fit, as the descriptions do vary from concise to totally pathetic. Some have had only 1/4 machined away and some are 90% gone. The most worn are candidates for milling your own brand of slot and tenon for tops to be attached by SHCS. I have made some steel, some aluminium and a rotatable brass set made out of a section of hexagonal bar.

Making the complete jaws is possible with a rotary table on the mill, but I don't have the patience.

[BufferParticipant @buffer]

Here's how I make my jaws last.

[old martParticipant @oldmart]

Good idea, Buffer, and there is room at the other end of those jaws for another three for outside use.

[JohnFParticipant @johnf59703]

I seem to recall that many years ago Myford Nottingham sold a modified set of soft jaws that used a similar idea to Buffer's system above but they used Hex bar for the inserts and the recess in the jaw was machined to accommodate the Hexagon. Depending on what was being machined etc this gave up to 6 stations on each set.

Always thought it was a great idea !

John

[egaParticipant @ega]

Here is Myford's rather unsatisfactory leaflet:

[old martParticipant @oldmart]

That Myford picture by ega is exactly the design that I used for the brass jaws I described in an earlier post, made simply because I had a bit of hexagon brass stock laying about. The have not found a job yet.

[Neil LickfoldParticipant @neillickfold44316]

Softjaws are great for one off jobs, but I find that when it comes for the repeat of that job, having to recut is a pain compared to just loading the previous setup. At home, I would rather make a sleeve with a step in it etc to hold the part. Mitybite do a range of inserts for softjaw solutions. One that I did at work was a piece of angle and screwed to the jaw with the hole very slightly offset for the countersunk screw. The inserts can be replaced and then the previous parts are run again. For worn chucks, having a support piece in the back to help the jaws pivot and then clamp down on the front is very useful. The back support will vary with each worn chuck. Some might only need a piece about 0.05mm or 2 thou smaller than the short part being held, while others might work better with a piece the size of the work piece as a support.

[robjon44Participant @robjon44]

Hi all, I would go with ega's drawing above, on the rare occasions I have needed small bored soft jaws I have 2 sets lovingly hand crafted from nuts with 1" diameter threads, one with the corners inward & one with the flats inward, grip a small piece of hex bar, then skim the o/d to clean up, dot punch, remove, drill & tap for securing (cap screws) & Bobs your uncle or lazy person (your choice), tie up on piece of string & hang up in plain sight ready for the time they are required again & yes I know its a little crude we are not making fings for Mr Rolls & Mr Royce but in a previous lifetime I have done.

BobH

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by ega on 31/07/2022 23:24:11:

Here is Myford's rather unsatisfactory leaflet:

I suspect the Myford soft jaws were bought in from:

Rod

[egaParticipant @ega]

Rod:

Interesting.

I don't suppose you have the "feature article on page 82"?

[Roderick JenkinsParticipant @roderickjenkins93242]

Here you are:

[egaParticipant @ega]

Rod:

Many thanks for this interesting article by the late Stan Bray.

The precise construction is not clear, to me at least, from the Myford leaflet but I suppose that the jaws are located on some form of register and, of course, retained by the screws seen in SB's photo.

In my case, I bought a set of soft jaws and machined locating recesses in them for replaceable slave jaws.

If the slave jaws are merely trued with a reamer without stabilising them in some way the result might be unsatisfactory.

[Steve NeighbourParticipant @steveneighbour43428]

If any of you watch 'Blondie Hacks' on YT – she made some copper soft jaw 'covers' which work really well.

They are quick and easy to make – I used a piece of copper sheet, and cut a template to suit, folded to shape so that they simply 'clip' onto ea jaw.

obviously nowhere as good as a set of purpose 'machined' ones – horses for courses !!

Steve

[Paul LousickParticipant @paullousick59116]

Protective jaw covers are OK to prevent marking the part if run-out is not critical in a 3-jaw chuck. For an accurate mounting if the jaws are worn or not an adjustable chuck are machinable soft jaws.

Youtube video showing how to bore the soft jaws to suit your job using a jaw spider **LINK**

[DC31kParticipant @dc31k]

Posted by ega on 03/08/2022 09:45:31:

The precise construction is not clear, to me at least, from the Myford leaflet

The photo below the Myford leaflet explains it very well. The groove in the hexagon locates in the tongue on the base jaw. The flat of the hexagon (which is perpendicular to the groove) locates on the step in the jaw, the back side of the cross-groove milled in the jaw.

It relies on the pressure from the work pushing the soft jaw against the step, so only five out of six degrees of restraint are provided, so you could not grip the inside of a tube with the jaws, but for normal, external gripping, it should be highly repeatable.

The concept is 50% of a traditonal tenon-and-groove two-piece jaw setup. See for example,

https://www.chestermachinetools.com/product/3-jaw-self-centering-2-piece-jaw-chucks-plainback/

Soft Top Jaws for Bison 2 Piece Jaw Chucks American Cross Tenant By Bison

For information, this type of jaw is made to ASA B5.8 or IS 15248 2002 or ISO 3442 (and the dimensions in the international versions are direct metric conversions of the original imperial units).

Have a look at 11:47 onwards here: https://www.youtube.com/watch?v=JplJAxX3buA

[steamdaveParticipant @steamdave]

Just to show that I do follow up on the answers to my questions. Well, some of them!

These are my soft jaws. 2-1/4" Ali hex. The holes are .700" and the jaws are locked in place by M3 cap screws with the heads reduced in diameter a few thou. The front faces have deliberately not been faced.

Dave
The Emerald Isle

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