Slicing Tubing

[CaddyDaddy]

What do you fella’s use (method/fixture/etc...) to slice in half, lengthwise a piece of styrene tubing? For example, say I have a 3” long piece of .080 tubing. How would I cut it so I end up with two separate pieces, each 3” long, and each half-round? As always, you have my thanks in advance!

[Rick L]

Good question. Unless you have access to a milling machine, I can’t answer that.

[Bainford]

It's pretty tricky to get two nicely symmetrical tube halves from one piece of tube. It may be much easier to start with two 3" long pieces of tube and cut away half of each piece. File, sand, trim as necessary to obtain two identical 'halves'.

[Muncie]

just the standard hobby shop jeweler saw.  It's straight and long enough that it can smoothly follow the cut. Sometimes it works out with one cut.  I've also used Trevor's method. 

Also works great on aluminum tubing.

extra fingers out of the way. it cuts flesh easier than plastic.

Edited February 8 by Muncie

[Ace-Garageguy]

Frankly, I wouldn't even try to saw 80 thou styrene stock in half. 

I'd just sand half of it off.

Pretty easy if your abrasive is stuck to an imobile flat surface, and you draw the stock along it lengthwise.

I quit trying to save every last bit of stock.

My time is worth more than a 3" piece of .035" half-round wasted (you'll lose at least .010" for the saw kerf).

Edited February 8 by Ace-Garageguy

[NOBLNG]

2 hours ago, CaddyDaddy said:

What do you fella’s use (method/fixture/etc...) to slice in half, lengthwise a piece of styrene tubing? For example, say I have a 3” long piece of .080 tubing. How would I cut it so I end up with two separate pieces, each 3” long, and each half-round? As always, you have my thanks in advance!

Does it need to be hollow? You can buy Half round solid in most smaller sizes. If I had to do it, I would use a piece of.040” thick as a guage. And use a scriber or back of a #11 blade to scribe a line. Flip the tube around and do the opposite side. Gently deepen the scribes until it parts.

 

Edited February 8 by NOBLNG

[CaddyDaddy]

I like both the “sanding” and the “.040 fixture and scribe” ideas.

Now, let’s take my original question one step further:what to do when cutting a much larger diameter tube, such as to use as a transmission/driveshaft tunnel?

[Ace-Garageguy]

5 minutes ago, CaddyDaddy said:

I like both the “sanding” and the “.040 fixture and scribe” ideas.

Now, let’s take my original question one step further:what to do when cutting a much larger diameter tube, such as to use as a transmission/driveshaft tunnel?

IIRC, the largest diameter Evergreen tube is 1/2 inch, suitable for a driveshaft tunnel but not for a trans hump.

Anyway, I've done that one frequently, and that's where the razor-saw works a treat.

Mark your cut lines first so you know they're true to each other.

It's easiest if you can fixture the tube so it doesn't roll around while cutting. 

Something like the center groove of an aluminum X-Acto miter box can work well, but there are lotsa ways to do it.

A setup like NOBLNG's is another good option...probably better than the razor saw.

 

[Rick L]

To get a flat even half round out of tubing, lay the .08 tube down on a flat surface with double sided tape and sandwich each side with a flat layer of .04 shim stock along the lengths also taped to the flat surface. Sand down the tube length wise with a sanding block until you reach the shim stock.

[Skip]

I have done this before, it's quite interesting what you can do with a file and a small machinist vise. First chuck the tubing in a vise to the desired cut depth, then file it down to the top of the vise jaws. The end result is a parallel depth of cut with little if any need for additional dressing with either a file or sanding stick.

[dusty_shelf]

You can cut a piece of sheet styrene that is measured to the circumference and length needed, gently heat it until soft and then wrap it around a rod/dowel that is of the correct diameter.