Sunday, October 23, 2011

Making A Third Hand Jig

This is a great lesson in why it is often easier and cheaper to buy something than make it. You can get a 3rd Hand Jig for under $7.00 which functions reasonably well and even has a magnifying glass. But as with many things that is too easy a route to take.

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Some 3/8” steel chucked in the lathe.

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Groove cut.

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A Shaplane radius tool is used to turn a ball end. Setup takes a while but once done it’s easy to get relatively uniform results.

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The finish is pretty good.

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One down…

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I needed 6 but I cut seven, just in case. Notice there’s a bit of variation in the turned down shanks. As you can see by the precision CAD drawing I’m not that worried about tolerances. The goal was to make a functional third hand tool as rapidly as possible.

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Dressing the stem a bit.

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Drilling a hold for a push fit on the shank of an alligator clip.

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The alligator clip ends are a bit springy so they will stay put in the hole. Later I may make a better tweezer to replace them.

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Setting up the vise so a hole is drilled on center. The ruler trick works well.

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Drilling…

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Three pieces with 1/4” holes.

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Drilling for a #8 tapped hole.

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Three pieces done.

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Drilled and reamed a 5/8” piece of steel rod for the shank of one of the ball pieces.

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Drilled for a #8 screw.

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Another part done.

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Drilling three pairs of steel plates. Two holes for the balls and one for the #8 screw (one piece clearance, the other tapped.)

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Tapping.

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Almost done, sort of.

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Matched pairs screwed together.

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Ends radiused for clearance and aesthetics.

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Drilling some brass rod for a press fit on the heads of the #8 SHCS.

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Knurling.

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Cutoff.

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Knurled heads pressed on the screws. Note that I sanded and polished the parts.

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All together. It mounts in one of my Panavise bases. Once tension was set on the screws it holds well in position and adjusts relatively easily. Whole thing took about 4 hours not including the time spent cleaning up the shop afterwards…

6 comments:

John Bear Ross said...

Very nice. What are you going to do with the $7 you saved? ;)

Best,
JBR

Nick Carter said...

It goes towards the $600 I just spent on a used makerbot...although my accountant says that's not how finance works.

BetterDriver said...

You should put some hemostats on there, instead of those weak clips. They lock, and I much prefer that to the weak clips.

Nick Carter said...

Yup, that's the next project, putting better grippers in place.

Anonymous said...

I would like to know your thoughts on the SHAPLANE Radius Tool, I have a 10K myself and would like to get a ball turner. What model are you using? I was looking at the model that does the 1 5/8 inch ball-item# A1-248-05.

Thanks for you time.

Nick Carter said...

I have the smallest one, the 1-5/8" ball. It works ok but setting the toolbit is a bit tricky - you have to measure between the back of the toolholder and the tool tip. It would be easier to use in a lantern toolpost rather than a quick change toolpost. I think the Holdridge ones are superior and there are other options such as making an "up-and-over" style or getting one of the inexpensive OMW ones.