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Harold Hall

Workshop Processes

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Finish the jaws with a little hand fitting. Fit a fine tooth straight edged file and using the safe edge, into a vice and slide the jaw backward and forward along this. I find this much easier than placing the workpiece in the vice and moving the file. Remove burs, etc. stamp the jaws 1, 2 and 3 ensuring that this is done on the correct jaws, and the jaws are finished. If you make a second set it is essential that they are kept in sets. In this case mark the jaws 1A, 2A and 3A and the second set marked 1B, 2B and 3B.

 

If you attempt the task I do hope you find it not that difficult. You will though have to keep your mind on the job ensuring that you machine the required radius with the correct offset, etc., etc. Photograph 5 shows the finished result and that I made a second set that were adapted by fitting hexagonal jaws.

 

If you have some low profile clamps you can both thickness the jaws and make the grooves by machining them as I did, Photograph 6 and 7. This bypasses any error in the vice such as jaw lift and the inner surface not being parallel with the vice's base, etc. See page elsewhere on the site for details of low profile clamps that can be made in the home workshop.

 

Close examination of the two Photograph shows that I added an additional support when machining the groves. The low profile clamp that I used is capable of considerable clamping force and I was concerned that just possibly it may move the fixed jaw with disastrous results. I think I was being overcautious but it is better to be safe than sorry in such critical operations.

 

Material

I have not yet mentioned the subject of the grade of material to be used. In view of the amount of machining to be done, especially the teeth, a free cutting steel will be very beneficial. Unfortunately, 230M07 (En 1A), whilst made in rectangular sizes they are not easy to obtain. Rather easier is square bar in a reasonably wide range of sizes. I used 32mm square that I then split in two loosing about 1mm with the saw blade. This gave me two pieces nominally 15.5mm wide which had to be reduced to 15mm. I would also advise that it would be very worthwhile purchasing a new cutter to machine the teeth with, as it will cut much better than one that has been much used.

 

I do not see this project as a means of saving money, though if you make more than one set it just maybe, but as a way of acquiring some soft jaws for a chuck for which they are no longer available. They would also make a useful project for the workshop owner wishing to take on something different from the usual turning and milling activity.

Soft Jaws for the Three Jaw Chuck, Making
Soft Jaws, Making

Drawings

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Soft Jaws Making
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 5

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 6

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 7