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View Full Version : Tube coping (mitering) belt sander?



glenj
05-03-2004, 04:28 PM
I am thinking of building/converting a belt sander to use it for coping or mitering thin walled steel tubing. I picture some interchangeable sized rollers on the drive shaft end for the various cut sizes and a crowned belt tracking idler on the other end. To hold the tubes a set of "V" jaws in a vice. To position the tubing, a small (5"x5" travel) cheap X-Y vice (rebuilt so it actually works) and some sort of rotary base. The tubes are between 3/4" and 1.5" diameter and have a wall thickness between 0.016" and 0.035".

Has anyone here ever built a belt sander or have any experience with belt tracking? I've tried making 2-1/2" dia miters on the sander drive drum as it is and it seems to work fine, not eat the belts too quickly etc. Any sage advice before I jump in?

ralenr
05-03-2004, 08:20 PM
glenj,

Take a look at these links. They gave me a number of ideas. Maybe it will trigger some things for you too.

[url="http://beaumontmetalworks.com/index.html"]http://beaumontmetalworks.com/index.html[
http://www.stephenbader.com/
http://www.unigrinder.com/
http://www.mstarling.com/The_Craft/Tool_Plans/_Belt_Grinder/_belt_grinder.html

Allen

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CCWKen
05-03-2004, 09:29 PM
Might be easier to just get one of these.

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=42324

For $30, it doesn't seem worth making a bunch of drums. All you need is a bi-metal hole saw for the size tubing you're cutting. These can be used with a drill or drill press (1/2").

wierdscience
05-03-2004, 11:36 PM
I got my hands on one of those belt copers that Trick tools sells and I have to say I'm hooked,it will cope ANY wall thickness tube even down to .025"

The one I used tracked the belt on the motor drive end for obvious reasons,the motor end pulley also carried the crown,the work end roller was straight.

Biggest think I did notice is in order to facilitate a wide range of tube sizes on a single belt length the tensioner had a large travel,about 8" as I remember,it was a piece of telescopic tubing(square)with a stout spring.

The tracking was simply a gimble affair,picture a face mount ac motor with a 1x1" square cross section ring bolted on the front,the ring had two pins drilled in and the tracking/tensioner had a bigger ring welded in with coresponding holes in it,the motor was able to pivot about 5* side to side by means of a large wing lever.

The work end belt rollers are a straight faced steel roller turned to a diameter to match the tubing being coped LESS the thickness of the grinding belt.The rollers had their own ball bearings(sealed)and the shaft projected through each end by about 1/2".Each end had two opposing flats milled on and the shaft simply rested in two 3/8" wide slots milled in each side of the frame,belt tension holds them in.

It had a 6" mill vise with a swivel base and v-grooved jaws.The centerline of the v-groove was on the centerline of the belt roller.

The vise was mounted on a set of 1" linear bearing blocks for the x travel with a lever to provide fast travel back and forth across the width of the roller/belt.The y axis was a set of rods with bronze bushings and a acme threaded leadscrew with a simple handwheel.

It worked real nice,you just rough cut the angle on the tube with a chop saw ,set the vise angle and ground away till you hit your layout line.It used the blue Zirconia belts and a cool mist system to both control the dust and keep the belt and tube cool.

We were mitering and copeing 2"-.095" chrome-moly tubing,a 45* saddle took about two minutes start to finish,real slick.I got to build one.

glenj
05-04-2004, 01:14 PM
Those drill powered tube notchers don't work on the tubing I'm using. It's very hard and very thin. Clamped in a split block of the right diameter in the vice on the mill and cut less than 1/8" from the block the cutting teeth catch and crumple the leading edge of the tube. These tubes are between C$60 and C$100 per tube so I want a solution that can reliably cut the tubes without the risk of damage involved with hole saws.

Thanks for the links to the belt sanders. I guess I'm trying to build a smaller, less powerful version of the following.

http://www.vansantent.com/coping_machine.htm

Here is another setup I use in the lathe to miter the tubes. Anything over 0.025" it works just fine. These new tubes are .016" thick though.

http://img30.photobucket.com/albums/v91/glenjohannesson/Shop%20Photos/Frame%20Building/Tube_Mitering.jpg

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