Precision filing thin brass tubing

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jacob
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Precision filing thin brass tubing

Post by jacob »

I have some thin 5/32 brass tubing that I need to make slightly shorter (about 1/16").

Ideas:
1) Clamp it in a vise and use a flat file. My concern is that I'm going to pinch the tube which would be catastrophic (for the project).
2) Clamp it in the drill press and use the press to slowly push it into some sandpaper presumably giving enough control to grind the brass away. Pinching concerns are slightly less due to the 3-jaw chuck but still there.
3) Freehand or build a jig to feed it into my disc sander.

Burrs are also a concern. I don't own a deburer and my reamer is too big. Any way to ghetto this? Round nail? End of drill bit?

Also looking for a ghetto way to lay out the exact length w/o "blue ink" and a scribe. I have a pair of plastic calipers :-P

sky
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Re: Precision filing thin brass tubing

Post by sky »

Put a piece of sandpaper on a table. Mark the desired length with an exacto blade by rolling the tubing and marking the desired cut line all the way around. Hold the tubing in your hand and rub it on the sandpaper. Check frequently to see that the end of the tubing is parallel with the mark.

Cheepnis
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Re: Precision filing thin brass tubing

Post by Cheepnis »

W/O access to an appropriately small tubing cutter I would use the finest flat file I've got, set flat on a table, then very gently file the tube down by moving the tube across the stationary file. Brass shouldn't burr too bad if you go very slow. When you're done some emery cloth can clean up the outside and a needle file the inside, if need be.

Campitor
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Re: Precision filing thin brass tubing

Post by Campitor »

I've done this sort of operation. Using a box cutter blade, mark a line on the tubing at the desired length. You can use a sheets of paper as shim to hold the blade to the correct height while you spin the tube vertically against the blade. You can also hold the blade vertically while you spin the tube horizontally. Brass marks easily with a fine blade

Once you have the proper removal height marked on the tube, you spray glue a piece of sandpaper, (600 or 800 grit) to a flat tile and using your hand, gently rub the tube on the paper until the desire amount is removed - or use your disk sander and make sure to clamp a piece of wood at a 90 degree angle to the disc sander to help you hold the brass tube at the correct angle.

ZAFCorrection
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Re: Precision filing thin brass tubing

Post by ZAFCorrection »

Do it materials science specimen style. Let the end of the tube set in some kind of epoxy which you can easily dissolve later. That will provide a support to cut or polish to your heart's content with good control and minimal risk to the tube.

http://www.ebsd.com/hints-tips-for-ebsd ... e-mounting

wheatstate
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Re: Precision filing thin brass tubing

Post by wheatstate »

I would consider clamping a the largest drill bit that slides inside tube in the vice as a buck.
Tube would rest on top of vice.
Perhaps with a hole in a wood block to prevent drill bit rotation.
A drop of hot glue, tape, paper could make tight fit
Drill bit height could be measured off vice and be slightly more than target length.

basuragomi
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Re: Precision filing thin brass tubing

Post by basuragomi »

I would drill a hole equal to the tube OD in a block of wood as a makeshift collet. Stick it in, use an exacto+calipers to mark the length and file. Maybe some hot glue to fix it in place around the back end. Doesn't seem wide enough to risk pinching unless your files are really dull. If the end gets deformed use a drill bit shank or other round thing to round it back out against the wood.

jacob
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Re: Precision filing thin brass tubing

Post by jacob »

I chickened out and bought a mini tube cutter. https://www.amazon.com/gp/product/B0002SRK2G/ has delrin(?) support instead of two rollers so it can cut any length. To cut really short tubes, I superglued a wood dowel to the tube in order to hold and turn it and then used acetone to dissolve the superglue when done.

I used sanded off the outside burr using a piece of 400 sandpaper on the table and just free-handing it.

The inside burr is substantial though. I used a drill bit (fortunately I have a good drill index) while holding the tube in my hand (don't do this at home or you might shave off some fingertip skin!---possibly cover in masking tape); then used an exacto blade to round the edge. Not a clean solution but seems to do the job.

So overall a combination of all the suggestions above. Dunno why the vise/file was stuck on my mind when I asked ... probably too much recent focus on shortening steel rods.

Cheepnis
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Re: Precision filing thin brass tubing

Post by Cheepnis »

What was the application?

jacob
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Re: Precision filing thin brass tubing

Post by jacob »

I'm building a second clock.
See the first one here: viewtopic.php?p=228754#p228754

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Ego
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Re: Precision filing thin brass tubing

Post by Ego »

Last week I saw three traditional cuckoo clock pine cone weights in a 50 cents a piece junk pile and thought of your clock.

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