TGP Tubing?

[monkeyplasm]

I'm contemplating a project that will require some precision rollers.

Length of 6 feet and diameter anywhere between 2"-3". The diameter needs to be uniform and precise, runout (TIR) of 0.001" or better is desired.

I have found a product called TGP rod (Turned, Ground, and Polished) which I believe will provide acceptable precision. However, in larger diameters (say 2”-3”) this stuff is very heavy and increasingly expensive.

To reduce weight I've looked around for something like TGP tubing, but there doesn’t seem to be any such thing that I can find.

Weight loading on the rods/tubes will be extremely light, so a .065 wall tube would be just fine. I just can't have any surface imperfections (e.g. welded tube weld lines) or bowing (runout).

Anyone have suggestions of what product to look at? Thanks.

 

[dr_clyde]

I think your best bet will be to have a machine shop turn some heavy wall pipe/tube to size with a fine finish. That tolerance in that length is not really something you can buy off the shelf. I would look for a large hydraulic cylinder repair shop. They typically have lathes capable of turning that kind of work.

 

[A_Pmech]

TGP products are straight to around .001" to .002" per foot in those sizes.

At 6' wide, tubing that diameter will sag in the center of the span an order of magnitude more than your tolerance by it's own weight. If possible, go to a larger diameter tube to increase the moment of inertia relative to the section weight. The large moment of inertia also makes accurate machining of the tube OD easier.

Newspaper printing machinery uses precision rolls about 4' wide which may suit your purposes if you can use a narrower width. Many old machines are dismantled for scrap.

 

[Ohmthis]

I have seen tubing/pipe with a very heavy wall (1"-2"). That might be something that can be turned and polished to your tolerances.

 

[SM Racing]

One of my steel suppliers offers ground tubing. They use it for their NASCAR customers. They simply take regular DOM tubing (which I assume you could use regular tubing as well) and pass it through a machine that can grind the tubing to the exact diameter. you need.

 

[dr_clyde]

One of my steel suppliers offers ground tubing. They use it for their NASCAR customers. They simply take regular DOM tubing (which I assume you could use regular tubing as well) and pass it through a machine that can grind the tubing to the exact diameter. you need.

And that supplier is?

 

[Kevin54]

You don't explain what you are doing and that may help. You can use any tubing, the thicker the wall the better. Add a plug in each end, and either have a good press fit on the plug, or have a plug with 4 bolts, counterbored or countersunk to hold the plug in the ends. Have the tube then turned down to a specified diameter. After everything is turned down and you have the finish you want, then have each end bored and have a bearing inserted into each end. That way you will have the weight taken out of it, being turned down should keep things nice and round, and you can put any bearing in the end that you want. Plus doing it that way should keep your cost down considerably.