Perpendicular cylinders

[tenacioustanaka]

Here's a question my feeble mind just can't seem to work out.

When working with dowels or plastic tubes/rod, especially in small scale it is very difficult for me to get that accurate perpendicular cut at the base allowing the cylinder to stand perfectly erect. I can't figure out how to rig some sort of cutting or sanding jig to accomplish this. Normally I either cut or sand at too much of a bevel thus causing the rod to lean. Who here among us is the geometry whiz and can help me figure this puzzle out?

When I mean small scale I'm speaking of rods/tubes of Destroyer smoke stack size and smaller in 1/700.

[Ron Smith]

Here's a question my feeble mind just can't seem to work out.

When working with dowels or plastic tubes/rod, especially in small scale it is very difficult for me to get that accurate perpendicular cut at the base allowing the cylinder to stand perfectly erect. I can't figure out how to rig some sort of cutting or sanding jig to accomplish this. Normally I either cut or sand at too much of a bevel thus causing the rod to lean. Who here among us is the geometry whiz and can help me figure this puzzle out?

When I mean small scale I'm speaking of rods/tubes of Destroyer smoke stack size and smaller in 1/700.

Anything I need perfectly perpendicular that's over .125" diameter I chuck in my lathe after cutting too long and face off the ends to the correct length. Anything between .0625" and .125" diameter I use a mini-tubing cutter. Solid metal from .020" to .1" I can cut with a special sheer cutter that works kind of like dikes. Tubing and plastic rod below .125" diameter can also be roll scored then snapped free, careful alignment while rolling the score will make it perpendicular. One just has to be very careful cleaning up the end, no matter how you do it, with a file.

[Karsten]

I bought a Zona Mini Miter Box for use with a Razor Saw. It will do 45, 30, 60 and 90% angles. Cost about $5.00 plus shipping and a razor saw.

Karsten

[RNfanDan]

I bought a Zona Mini Miter Box for use with a Razor Saw. It will do 45, 30, 60 and 90% angles. Cost about $5.00 plus shipping and a razor saw.

Karsten

Exactly the thing I was going to suggest, too---not necessarily Zona brand, as there are a number of labels these items are sold under. Personally, I prefer the extruded-aluminum type, but there is also a hard plastic version available. I've had my aluminum one for over 20 years and it's indispensible.

It has a variety of grooves cut into it for both large and small stock. I lay the rod or tubing so that the end protrudes just past the box-edge, then either sand, file, or blade-cut the stock square. Works like a charm!

[Karsten]

I bought a Zona Mini Miter Box for use with a Razor Saw. It will do 45, 30, 60 and 90% angles. Cost about $5.00 plus shipping and a razor saw.

Karsten

Exactly the thing I was going to suggest, too---not necessarily Zona brand, as there are a number of labels these items are sold under. Personally, I prefer the extruded-aluminum type, but there is also a hard plastic version available. I've had my aluminum one for over 20 years and it's indispensible.

It has a variety of grooves cut into it for both large and small stock. I lay the rod or tubing so that the end protrudes just past the box-edge, then either sand, file, or blade-cut the stock square. Works like a charm!

I would most likely agree with RN that maybe the Zona is not the best as it is plastic and the slots of the blade is pretty tight...I time I am sure it will get sloppy if I model that long.

I did just come across this that includes the saw and may be a better way to go in hte long run.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... :IT&ih=002

Karsten

[reigels]

A tube cutter will work down to about 1/8 of an inch. Smaller than that and I usually just score the tube by rolling it under a razor blade or x-acto held perpendicular to the tube and snapping it. You might want to try a block of wood or some other 90* solid to align the stock and the blade.

http://www.ares-server.com/Ares/Ares.as ... t&ID=20132

[Pieter]

Another trick which also helps in getting your funnels or other hollow objects to scale thickness is the following. Make your cylindrical object some 0.1 mm thinner than needed. Cut it some 5mm shorter then actualy needed. Take a piece of paper and mark out a rectangle in which one base is the exact length of your object and the the other 3.14 times the diameter of your cylinder. Cut out and soak in diluted white glue. Wrap it around your cilinder and when dry reinforce with superglue. Sand the edses. This is actually an old card modelers trick which is used to reinforce masts and funnels.

[Andy G]

To mark a truly perpendicular line on a cylindrical rod/pipe before cutting, I do this:

Get your pipe.

Get some straight-edged paper longer than the circumference of the pipe. (Cigarette papers are good for 6mm diameter and below.)

Start wrapping the paper carefully around the pipe at the correct distance for the mark.

You'll see, as you wrap, that the straight edge of the paper only truly overlaps and lines up with itself if the paper is perpendicular to the pipe.

With care, you can jiggle the paper to ensure that the angle is correct as you wrap.

Once two or three layers are on, hold the paper in place, and mark the pipe & paper with a felt-tip pen. Remove the paper.

Andy

[RickF]

I would agree with the use of a mitre box for cutting. For trueing up a previously cut tube, use a "V" block, or obtain a piece of angle iron and grind the end flat and true. Just press the tube into the "V" and gently sand/file the end of the tube using the angle iron as a stop.

Rick

[tenacioustanaka]

Excellent, Thanks to you all.


Looks like for my very small applications that angle iron trick may be the best way to go for now. Once I get to those stacks then I may scope out a small pipe cutter. Of course that mitre box looks tasty too. Hmmm, decisions decisions.