Holding thin round stuff

    I've got a situation where I have to drill 3 holes, then accurately cut out a slot in the lid of a small cookie tin. I made the fixture pictured
here to do the deed: http://www.flickr.com/photos/steamboat_ed/6098845979/in/set-72157624880649814     --The trick I came up with: I layed the thing out with a measuring tape, making certain that the center of the round thing was a little over some nice round numbers in X and Y, relative to a reference corner. Once everything was drilled, tapped and fastened in place I put the fixture in the vise with a part mounted. Using a dial indicator that touched the outer rim I found the exact center of the part. I reset my DRO to 0,0 here and then went looking for the edge of the fixture with an edge finder. I marked down the numbers, then milled those two edges to 'round out' the distances. Next time I use the fixture I know the center of the round thing is exactly 6" in X and 2" in Y, instead of some weird number I'd never remember.     --Still and all I'm not real happy with the fixture and I'd be interested to know what others may have done in similar situations. I didn't want to go overboard on design since I'm only doing maybe 50 of these and the 'customer' is me. ;-)
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Holtzapffel's suggestion for clamping oddly shaped artsy workpieces was a custom wooden 'collet' closed by an external steel ring. The lids could use an internal plug for support. I make such things out of either glued plywood scraps or a chunk of firewood, depending on grain requirements. If it's stationary you could close it with a Vise Grip chain wrench.
The wood doesn't scar the finish or damage cutters. Scrap credit cards like AARP sends are good for padding finished or uneven work in a milling vise too.
jsw
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For one-off's I've used plaster of paris to make a holding jig. It's readily removed with just water. In your case could you spray a part with mold release and fill it with bondo, or similar, to make the jig? Art
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wrote:

You must be thinking of dry wall compound cause plaster of paris is permanent, been playing with the stuff for the last couple of weeks. Took awhile to figure out the correct mix again, probably have it written down somewhere. Plus BTW, water first, drill, then powder!
Wood works for the OP, I milled a perpendicular round hole through thin walled round tubing once. For those lids, I'd made a jig to have it centered and clamp it from the top. Like a plywood disk screwed to a rectangle of plywood that is left bolted to the table then one clamp to hold it down the work.
I'm getting to the point of being afraid to throw anything away cause there are so many alternate uses for things. Like yesterday I was using one of those rubber spatula's for an extended finger to thread in a bolt that I could only reach with one finger. Might as well toss that one in here. Yesterday I was cutting up maple slabs and the cheapy 2X3 table saw stopped while cutting two at a time. The motor is bolted onto a approx. 2" X 3" steel box. Found the clip broke that holds onto the brush holder. Tryed to duplicate the clip and gave up and soldered the wrong wire to right holder. Got it all together and as I plugged it in I said "What could possibly go wrong?" and it spun the wrong direction. Took it apart again, plus had to drill out the housing to punch out the blind bearing, and instead of re-soldering to the other brush holder I turned the stator 180 degrees. Took about 3-4 hours, but It has lots of life left now.
SW
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    [ ... ]

    Hmm ... in buying used electronic service toolkits, I wound up with a set of spring-loaded thimbles with spring-loaded clips for various sized hex nuts -- which is great for that particular task. (I have, before, used double-sided tape to hold the nut to the fingertip.)
    As for screws -- I've got both straight and Phillips screw starters which have a twist-lock. You pushed the screw onto the end of the driver and part of it rotates to lock the screw in place. For the straight blade, it is the middle which rotates relative to the rest of the blade. For the Phillips, one cross-blade rotates relative to the other,a nd both have gripping surfaces. Obviously, these are useless for applying much torque, but great for starting screws -- or for picking screws out of recesses -- cock the driver, move it down onto the screw head, and press. When it goes "snap" pull out screw and driver.
    I haven't seen those in stores for years -- but presumably someone still makes them.
    Enjoy,         DoN.
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Used to be a staple item at the radio/TV supply places I used to go to. Another business gone the way of the buggy whip. Had another sort that worked better, a variation on the wedge driver for slotted screws, where there's two right-angled petals that get expanded by a plunger. That one really locked the Phillips and crosspoints in place. I've see a smaller version at the local model railroad supply where they've got lots of small specialty stuff like that.
Anymore, you can get really tiny rare earth magnets which solves the problem of pulling trim screws out of deep holes. Useless for nonmagnetic stainless and nylon numbers, but those are rarely in the bottom of holes that deep. I use small disk magnets in sockets and nutdrivers for starting nuts in the same circumstances. Particularly handy where the bottom area is inaccessible and a dropped nut is gone forever or worse, will get caught in the works.
Stan
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    [ ... ]

    [ ... ]

    That sounds like a neat approach.

    Hmm -- a No. 1 Phillips, a No. 2 Phillips, and perhaps a No. 3 Phillips and I would be happy there.

    Unless they come from my drawers of screws. I've picked up quite a few large bags of SS Phillips hardware at hamfests over the years. :-)

    Except for brass nuts -- mostly found on terminal studs on the back of D'Arsonval style meters, where magnetic materials are a no-no, and places where the environment can be nasty -- as in telephone junctions boxes on the outside of a house. (Actually, they used them indoors a lot too, once upon a time.

    Or -- can cause short circuits down the road. I'm currently working on a couple of old Tektronix 7000 series 'scopes right now. The first one (a 7704), had bad (low resistance) 100 uF 18V electrolytic capacitors in the power supply -- replaced, but other things are not working right either Lots of things to trace out in that one. The other one (a 7623 storage 'scope) has two 1800 uF 75VDC electrolytic caps which appear to have gone open or dry, and I'm not sure that I can find any of the same format (tab mount on PC board through holes like used to be in old TV electrolytics), so I may have to do some creative modification to mount something which will fit and work.
    It was a major task, digging out an electronics workbench which has been buried for about fifteen years (and which mice and a chipmunk had used for a smorgasbord with acorns and sunflower seeds. :-)
    Enjoy,         DoN.
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wrote:

Used to be a staple item at the radio/TV supply places I used to go to. Another business gone the way of the buggy whip. Had another sort that worked better, a variation on the wedge driver for slotted screws, where there's two right-angled petals that get expanded by a plunger. That one really locked the Phillips and crosspoints in place. I've see a smaller version at the local model railroad supply where they've got lots of small specialty stuff like that.
Anymore, you can get really tiny rare earth magnets which solves the problem of pulling trim screws out of deep holes. Useless for nonmagnetic stainless and nylon numbers, but those are rarely in the bottom of holes that deep. I use small disk magnets in sockets and nutdrivers for starting nuts in the same circumstances. Particularly handy where the bottom area is inaccessible and a dropped nut is gone forever or worse, will get caught in the works.
Stan
***************
I still have a couple from my tv/radio repair shop days of yore. They're marked Quick Wedge and they have a site. http://www.quickwedge.com / Art
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    [ ... ]

    Aha! i finally found it - -a single one marked "Phillips MP-1" which will handle from #1 through #3 sizes, at a price of $27.23. It is on this page:
    <http://www.quickwedge.com/1000v.htm
along with a few non-holding ones.
    Thanks,         DoN.
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A few smaller tool companies such as Cal-Van, K-D, make screw starter-extractor tools sold in autoparts and retail stores. (K-D 2282 Screw Holder and various other models)
The ones I have will lock into either slotted or philips recess screw heads by cocking the mechanism on the end, then pressing the tip into the screw cut/recess to lock the screw onto the tool. These types doesn't have an actual molded handle, just a knurled section on a length of aluminum round stock, and a magnet on the back end.
-- WB .........
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On Tue, 6 Sep 2011 19:23:06 -0400, "Wild_Bill"

OTOH, Robertson drive fasteners are automatically held in place by the tapered mating surfaces of the driver. Gerry :-)} London, Canada
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Gerald Miller wrote:

Not the ones I've seen and had to remove. Every damn one of them was sloppy, and I burnt up a bit about every six screws because they would wear down the corners till they just spun in the screw heads..
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00:23:18 -0400 typed in rec.crafts.metalworking the following:

    Is that a problem of the bit design, or of the bit construction?
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pyotr filipivich wrote:

I have no clue. I used new, brand name bits on existing screws in my garage. The former owner had built racks that hung from the roof out of 2x4s and plywood. they weighed several hundred pounds each, and hung so low they were in my way. I never want to see another of those screws again since I had to remove the damaged heads with a surface grinder, then use a crowbar to pull the wood off the threads. Then I had the fun of removing the damaged screws with vise grips. At one time there were a half dozen mobile factories around here, and the place was crawling with surplus hardware. The used barrels of those damn things, and a lot of it ended up at the local building surplus dealers. they may have all been rejects, or salvaged by the original owner. He was the local 'Mr. Fixit' for the subdivision and I don't think that he ever did anything right.
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15:24:31 -0400 typed in rec.crafts.metalworking the following:

    Hmmm, sounds to me like a "special case" where the screws had "set up" in whatever they were sunk into, and were not going to come out easily, regardless of the drive type. I've had a few of those myself. Such an experience can color one's opinion of the product. OTOH, Robinson heads do work well for installs.
    Does anyone still use slotted head screw?
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pyotr filipivich wrote:

Yes, for electrical work.
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On Wed, 07 Sep 2011 00:23:18 -0400, "Michael A. Terrell"

You must have been using a No. ! bit in a No. 2 fastener. Gerry :-)} London, Canada
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wrote:

We see good and bad examples of square drive bits and screws. I have a box of #2 square stainless screws that strip more easily than Phillips. T27 for me!
jsw
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On Wed, 7 Sep 2011 23:15:33 -0400, "Jim Wilkins"

He must have forgotten to seat the driver in the head and/or tried to drive a screw from a sideways angle. Neither works, as he discovered.

Have you tried another brand of driver bit? Quality varies all over the map with those things. DAMHIKT. What I hate is when the bit breaks in the screw. It can't be drilled out, but sometimes a prick punch can loosen it.

Yeah, torx rocks!

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These are definitely extra-soft screws, stainless steel deck screws from some overstock/closeout place. So I predrill and set the clutch light. All the other stainless screws from there have been fine; Robertson just isn't very popular around here even though the older carpenters are Canadien.
Snappy now sells quick change hex-shank tapered drill bits like the kitchen cabinet installers use.
http://www.woodcraft.com/Images/products/148014.jpg
jsw
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