Round Work, V Blocks and Parallels

[EmilioG]

Like most of you, I've had to drill holes or machine round rods, tubes, pipe etc..
What is the best way to hold round work in a milling vice like a Kurt?
I have some short tubes that fit on my B&S v blocks but I can't use the clamps
because they get in the way of the drill chuck or spindle w/R8.

Is it OK to sit these short tubes on parallels fairly low in the vise and clamp?
Can I use angle iron and clamp the tube on each end with vise grips?
What is safe and not safe? Please advise,

I would like to get Starrett 568's, also the thread on the B&S v clamps is a strange 5/16"-20!
Maybe I could cut short clamp bolts in 5/16-20? (don't have a lathe).

 

[rgray]

I had to hold a small round item in my mill vise just the other day. Can't remember what I was doing but I held it with a small V-block I made on the surface grinder out of some D-2. Worked great.
Pic is of a 1/2" boring bar in it....much bigger than I was working with, would probably want to use a spacer on the opposite side of the vise jaw with something that big.

 

[JimDawson]

Setting rods and tubes on parallels is completely acceptable. Rods are not a problem but tubes can be an issue sometimes in that the can be crushed a bit by the vice. You can't tighten the vice any tighter than the crush strength of the tube. Make sure when setting on parallels, that you keep the diameter below the top of the vise or it will just squish out.

Many times I set larger shafting right in the bottom of the vice, for keying and the like. Sometimes I will clamp a rod in the vise and then hang the end out to work on that. Angle iron works as you describe in some cases, I have done that before.

Just about anything is safe if you are comfortable that the setup will not allow the work to move under the forces of machining. About 1/3 of machining is figuring out how to hold on to the work.
.
.

 

[Andre]

Setting rods and tubes on parallels is completely acceptable. Rods are not a problem but tubes can be an issue sometimes in that the can be crushed a bit by the vice. You can't tighten the vice any tighter than the crush strength of the tube. Make sure when setting on parallels, that you keep the diameter below the top of the vise or it will just squish out.

That bring up a very good point. Whenever I have to hold a thin piece of material in a lathe chuck or vise I turn a wood dowel to snugly fit inside and boost the crush yield strength. Still can't wrench on the chuck key, but it helps.

This was a rolled piece of sheet metal from a friends factory-flawed Daisy 8888 front sight. With the wood plug it didn't crush in the 4 jaw and allowed me to shorten it with ease.

http://i1379.photobucket.com/albums/ah150/andregross3127/182_zpsa402765b.jpg

 

[machinistmarty]

You can make a set of jaws with vees milled in them. One jaw will usally suffice.

 

[EmilioG]

You can make a set of jaws with vees milled in them. One jaw will usally suffice.

That's a good idea. I've been thinking of making soft jaws in Al and brass. Just make them thicker and with grooves
to hold round work. Thanks to all.

 

[uncle harry]

You could drill some square or rectangular material to the rod O.D. & saw it in half making a pair of conformal jaws.

 

[EmilioG]

Thanks. I will proceed carefully. I can't afford to ruin these Cnc'd and welded parts.
I drill and tap the bungs (welded) then weld both tubes together.

 

[EmilioG]

This should work. (in a Kurt vise), or should I use just one v block?

 

[Andre]

This should work. (in a Kurt vise), or should I use just one v block?

Probably best to use two; four points of contact not just three. If you find it slipping, put some printer paper around the tube to prevent movement.