"Bob La Londe" wrote in message news:sgucqi$8k5$
1@gioia.aioe.org...
On 9/3/2021 2:32 PM, Jim Wilkins wrote:
Perhaps I should just wait until I have a setup problem it might solve.
DING! DING! DING!
I have a Starret one of these. I used it once to hold a small
cylindrical item suspended off the side of the vise. It worked a real
treat.
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Some tooling such as the 5C collet blocks and small 6-jaw enable a new range
of work-holding, but this thing probably doesn't.
One that has for me is a shop-made collet sleeve that holds bolts centered
on either the shank or threads in a 5C collet larger than the bolt's hex
head. For the gantry track I needed Grade 8 bolts whose threads began 0.180" (the channel web thickness) past the last shear plane. The head, shank and rolled threads aren't concentric or aligned axially.
The 3/4" diameter collet sleeve blank was bored 0.370" to match the bolt shanks, then tapped 3/8-16 which gave shallow grooves that the threads
readily engage. Grooves in the OD near the ends hold O rings that keep it together after slitting it lengthwise into three pieces.
My previous screw holder design is a cup with the bottom tapped for smaller screws that are threaded up to the head. I use it to add a tapered end and root-diameter pilot to make them self aligning, which is very handy on
awkward connections like the antenna mast joints up on my roof.
This began when I tried to turn Segway battery mounting studs from 1/2" stainless bolts for a robot, rather than sawing up a scarce reject chassis casting. Chucking the bolts by the hex head gave wobbling threads. The cup shaped holder provided a long straight engagement in a 1" collet and let me
cut the stud taper close enough to the head as well as drill and tap the end for the battery retaining screw. The ID of the cup has to be larger than the socket that tightens the bolt head.
After I get current projects done I'll slit the cups so they clamp onto the threads instead of requiring either the screw head or a nut to be tightened. They aren't always square to the threads and throw off alignment.
That's the nature of my industrial machine shop experience, experiments and prototypes that I usually designed as I made and tested them, sometimes in
my basement. Generally the company machinists demanded a finished blueprint
and refused to do any old-time hand work like filing to fit. I've collected
the fine tooth, safe edge Swiss-type files that change filing from crude to precise.
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