We do a lot of stainless steel tubing fabrication and have found that milling and abrasives both work well for coping. Using a small diameter mandrel on a stationary belt sander does a good job if the mandrel diameter is close to that of the tubing. Jancy makes a machine for this purpose but it's quite expensive and is sized primarily for pipe as opposed to tubing. Has anyone built such a machine?
I make a lot of Stainless steel handrails for houses and boats.
I use a 10" atlas lathe. The tube is mounted in a vise mounted to the toolpost rest. A holesaw is mounted in the lathe chuck and the tube end is fed across the holesaw. It works really well and can be used for very accurate angle coping.
The vise is very easy to build and basically consists of 2 u-bolts that hold the tube against 2 V-blocks. The V-blocks are mounted in the T-slot of the toolpost rest of the lathe.
The degree markings for the toolpost rest can then be used for the coping angle.
You can either use a holesaw and feed it in from the end, or use a roughing mill and feed it in from the side.
You just want to make sure that the center of your V-blocks matches the center of your lathe chuck.
It is much easier to use than the smaller tube cutting jigs, and cost almost nothing if you already have a lathe.
I can send you a picture of mine if you like.
I used to do this in a Bridgeport when building bow and stern rails for sailboats. Tip the head to change the angle. With the end mill, you feed into the side of the cutter rather than plunging as you would with a holesaw. This made it very easy to shave a very small amount off the the cope, or make a small adjustment to the angle. This was very important on something as irregular as a boat rail where odd compound angles on both ends of a piece were the rule.
A two piece split block sized to the tubing clamped to the table, or in the vise (or to the cross slide on a lathe), makes clamping quick and avoids marring the finish on the tubing. Most of what I did was 1" ornamental tube for which a 6 flute endmill worked very well.
I had a large hollow shaft worm reducer set aside to make a dedicated machine to avoid tying up the mill, but never got around to it.
Ned Simmons
Following up on Ernies suggestion of using a lathe for tubing coping, I gave it a try and it works really well. For holding the tubing, my Aloris boring bar holder worked really well with the added benefit of being able to quickly adjust the tubing position above or below the centerline of the mill for weird off center copes. The Aloris tool holder I have is sized 1" with a bushing to allow clamping 3/4" . I see in the J&L catolog that Aloris also has a holder that would do 1.25" and 1". These 2 holders will cover most of the tube sizes we deal with. I set the lock screws firmly but not rock hard and did not mar the tube. It was necessary to debur the edge after coping to get the tube out of fixture- it's a snug fit. All in all I'm very pleased and again thanks for the tip.
This works really well on stubborn tubing, like 4140. For oddball sizes, just bolt a big block of Al. onto the toolpost mount, bore it thru with an end mill in the lathe chuck, slit one side of the hole & drill/tap for a pinch bolt to grip the tube in the hole. perfectly on center!
bill m
Dueknot wrote:
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