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- Jan 22, 2011
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I've often touted soft jaws for the lathe as a simple way to get around a chuck that perhaps isn't quite up to holding a part for secondary operations, or smooth round bar accurately. I had a need for some the other day and remembered to take a few pictures of an easy way to do a set. I'll try to get them in order.
The part and some drops from an old job:
Drilled thru and counterbored to fit the socket cap screws that normally hold the top jaws on.
Roughly the idea while laying on the surface plate.
Setting up to bore them to size and true them up. Note the 1/2" drive socket in the master jaws. This is to give the chuck something to tighten against for boring the soft jaws. You have to use something of the diameter that will allow you to bore the jaws to size and get as much contact area for the part to be machined as you want. In this case, I didn't want/need much area. You could work it so they would be like pie-jaws, but you would have to do something different that round stock as I show here. Like I said.. easy Soft-Jaws.
Boring in progress.
Bored and ready
With part to be machined
Finished part in chuck
All this took about half an hour, including machining the part. TIR was near zero when finished. And of course, there's no way to get them back on the chuck exactly in the same position, but they can be rotated to a new position and bored there, or lightly chucking a part, snugged into place and skimmed. Or turned 90 or 180° and started from scratch. You can leave a shoulder instead of boring through as I did here if you need repeatable length chucking. I had to grab the inside of a spool shaped part, to I had to make sure they were short enough, and bored through. Uses only limited by imagination. I always get many uses out of the ones I make.
The part and some drops from an old job:
Drilled thru and counterbored to fit the socket cap screws that normally hold the top jaws on.
Roughly the idea while laying on the surface plate.
Setting up to bore them to size and true them up. Note the 1/2" drive socket in the master jaws. This is to give the chuck something to tighten against for boring the soft jaws. You have to use something of the diameter that will allow you to bore the jaws to size and get as much contact area for the part to be machined as you want. In this case, I didn't want/need much area. You could work it so they would be like pie-jaws, but you would have to do something different that round stock as I show here. Like I said.. easy Soft-Jaws.
Boring in progress.
Bored and ready
With part to be machined
Finished part in chuck
All this took about half an hour, including machining the part. TIR was near zero when finished. And of course, there's no way to get them back on the chuck exactly in the same position, but they can be rotated to a new position and bored there, or lightly chucking a part, snugged into place and skimmed. Or turned 90 or 180° and started from scratch. You can leave a shoulder instead of boring through as I did here if you need repeatable length chucking. I had to grab the inside of a spool shaped part, to I had to make sure they were short enough, and bored through. Uses only limited by imagination. I always get many uses out of the ones I make.
