Looking for setup suggestions

[Imechura]

Hello,

I have run into an issue that I am not quite sure how to approach. I was hoping to get some direction from wisdom of this forum.

I have a part (dozens actually) that is a 1/2" thin wall tube about 10 inches long with a 45 degree bend at the halfway point.

There is a diffuser installed at the tubing halfway point.

On one end there is a brass part that is press fit into the tubing.

I need to devise a way to remove the pressed in brass part from the tubing.

I can easily attach to the brass part because there is a hole drilled perpendicular to the part. But I have not come up with a good way to grip or clamp the tubing. I have about 2" of straight tube between the brass part and the bend.

I've tried to clamp the tubing between 2 v-blocks in a bench vise but the blocks pulled out before the part did, I'm afraid that clamping harder will crush the tubing.

I have a manual milling machine with basic tooling and a small lathe with basic tooling at my disposal.

I could try to make a better fitting v-block or a die in the milling machine to clamp on but that's quite a bit of work for me not knowing if its a good approach or not so I would like to see how others would approach it before I waste more time and metal stock.

Thanks

 

[GregSY]

I'd use a split circular block (not a V block) to grab the tubing. Look at the dies used in a tubing flare tool. In fact, I'd use the dies from a tubing flare tool. They give a lot of contact and have little ridges for more grip.

Amazon.com: TGR Professional Brake Line Flaring Tool- 45 Degree Set - Single, Bubble, and Double Flares : Automotive

 

[bhigdog]

Two blocks ( aluminum? ). 1/2" hole drilled/bored at the parting line. Mill a few thou. off one or both block faces ( trial and error ). Clamp tube in your vice between blocks......Bob

 

[sfriedberg]

I'm assuming the pressed-in brass part won't fit through a 1/2" hole. If it weren't for the bend in the tube and the brass part, you could use an ordinary collet and collet block. Or if you think that's a bit wimpy, you could use a Taper-Loc shaft bushing (or similar competitor's part). But the bend in the middle and the brass part in the end won't fit through a regular collet.

I would try round-bore clamping blocks first. Like V-blocks but cut to fit the tube OD with a slight (0.001" maybe) interference. [GregSY and bhigdog got there while I was writing. So three votes in favor of that.]

If that is promising, but not entirely successful, the next step up would be to make a collet-like clamp with more than two jaws, and ideally some jaw equalizing mechanism. This does not have to be real elaborate. Cut a female self-releasing taper in a large hunk of steel. Cut a matching male part with a 1/2" bore and a flat large-end face that protrudes slightly from the female part, then slit (bandsaw, EDM, Armstrong) the male part into 4 to 6 wedges. It would be convenient to turn a couple of grooves on the male taper that take large O-rings or retaining rings to hold the wedges together, before cutting it into the wedges. Make sure the rings will be buried below the surface of the taper when installed. Make a clamping plate from reasonably beefy (min 3/8" thick, 1/2" would be better) plate with a generous center hole to clear the tube and/or pressed-in brass part and several bolt clearance holes. Put mating tapped holes in the face of the female taper part.

You can put the workpiece in the clamp either direction. Since you are pulling something out of the tube, you might assemble the male taper part ("collet") with the small end toward the pressed-in brass part. Put the collet in the female taper part ("collet block"), slip the clamping plate over the appropriate end of the tube, and bolt it all up.

 

[Plane Parts]

can you freeze it on a bucket of water?

 

[magneticanomaly]

If you cannot get enough grip with any type of bored split clamp or collet on the straight section of the tube before deforming it unacceptably, I would try casting a clamp block out of Woods metal, or epoxy, or even concrete, to enclose the tube including the bend. Same idea as making a sand mold around a pattern in two parts. After the mold is hard, you could skim a few thousandths off for squeeze.

 

[Big Buck]

We use to make clamping blocks out of square aluminum with the hole dia. Drilled thru the middle them edm them in half. I've also removed end caps with air pressure making sure not to injure someone.

 

[NewGunPlumber]

Depending on how tight they are you could try a version of this

https://youtu.be/Q0q0E4GtSa4 gets useful about 2:30in