Hi all-- I use telescoping brass tubing of the hobby shop variety for my tuning slides. Currently, I cut it with a razor saw in a mini-miter box. Works OK, but it’s slow and does not always leave a good, even cut edge. Does anyone have any other ideas? I’ve thought of a plumber’s pipe cutter, but I’m afraid that it will mash the end of the tubing, leaving it unable to telescope. Chucking this thin stuff in my lathe will also mash it.
Paul, check with the hobby store. They make a cutter similar to the plumbers only the cutting blade is thinner.
Have you tried using the next size smaller tubing (or a wooden dowel) inside the tubing you plan to cut? it helps support the metal leaving a cleaner undeformed edge.
If you have a lathe, where’s the problem for just a bit of inside deburring, after rough cutting with a plumber’s wheel ?
You could also check out with a bicycle shop. They have special saw guides to cut clean the 1", 1"1/8, 1"1/4 tubes used for bike steerings. These support bearings and believe me they’re better cut smooth. If it’s high whistles sizes you’re interested in, you can examine these steel tools, and find inspiration ? Most good bike shops should have a Park Tools catalog, with a section for professional workshop tooling.
I understand the problem, and it’s tough. when I turn the 9/16" OD tube down to 0.480, the wall is only about 0.020 thick. Cutting used to be an “adventure”, until I remembered that my jigsaw uses straight-end, clamp-in blades. Pop in a 60TPI jeweller’s saw blade, drop in the miter guide, and voila! Smooth edge, almost no roughness, cuts without warping or bending. Sure, it’s a little slower than cutting wood, but it works and doesn’t damage the thin tube!
Cheers, 
Bill Whedon
There’s another aspect of this I forgot to mention. Brass hardness is all over the map when you buy it, unless you specify. I always buy “half hard”, which still has some malleability, but when worked will harden almost to the level of mild steel. If your tube is real soft, any wheel-type cutter is going to cause some swaging effect unless you support it inside with something harder than the brass - not wood. That makes it possible to damage your cutter wheel if you choose the wrong steel insert, and if it’s close enough to the ID to prevent the swage, you also have the possibility of getting it jammed in the tube unless your tolerances are quite close, and you’re working in a specific temperature range.
If you use a wheel-type cutter, cut a small fraction long to leave enough that you can remove the swage with a very sharp knife, or use a long multibladed tapered reamer to open it back to nominal.
Another solution is to anneal the cut edge by heating to somewhere around 650F (varies wth type of brass) and quenching. Probably too difficult to control with thin stuff unless you have a small electric annealing oven with a pyrometer. Once it’s annealed, a simple tapered and polished steel dowel can be used to swage it back to nominal.
Personally, I prefer the jeweller’s saw!
BTW, did you get the mill yet?
Cheers,
Bill Whedon
I use a 10" Miter saw for most of my cut off work. It’s the fastest way that I’ve found and works great for everything but ferous metals. Plus, you can set up a length jig. I’m also setting up my table saw to cut small pieces. (I can’t take the credit, though… miter saw idea by C. Goldie).
I used to use a pipe cutter, but that was way too slow and as Paul said, it misshaped the tube… that didn’t matter much since I then really misshaped the tube by pounding it over a steel mandrel, but the speed was a real issue.
Erik
[ This Message was edited by: ErikT on 2002-11-01 11:37 ]
[ This Message was edited by: ErikT on 2002-11-01 11:37 ]
I have a Bandsaw with a certain size blade that cuts metal and wood. It cuts brass very nicely.
I’ve been cutting windways lately with a milling machine and learned that you have to approach the metal a certain way or the loose ends will grab and twist up. Once you learn the right approach, it makes very consistant cuts.
On 2002-11-02 10:49, Daniel_Bingamon wrote:
I have a Bandsaw with a certain size blade that cuts metal and wood. It cuts brass very nicely.I’ve been cutting windways lately with a milling machine and learned that you have to approach the metal a certain way or the loose ends will grab and twist up. Once you learn the right approach, it makes very consistant cuts.
If you’re using a 2-flute, try a 4-flute cutter and increase the spindle speed. Brass mills well at a touch over 1000RPM. The swarf will be chips instead of threads, and the milled surface will be nicely polished with a slight “machine-turned” reflection. Hope this helps!
Cheers,
Bill Whedon
I’m using 4-flute cutters, it’s not the speed that causes the problem. I’m cutting a free edge of a slot and the metal is very thin and can be grabbed by the bit if you approach it in the wrong manner. Otherwise, it works fine.
BTW - To anyone cutting pipe with a plumbers pipe cutter, the sharp edge ring created by the cutter will reduce sound level big time. The air flowing over that bump creates some sort of interference wave in the bore. It can almost render a whistle silent. So before you blame it on the fipple voicing, make sure to debur first.
Okay, you have to “sneak up on it from behind”, so to speak. I understand. Those blade tips pack quite a wallop when hitting thin stuff! What wall thickness do you use? Mine is 0.040 nominal, which makes for a slightly heavy whistle (to which I add by using a solid brass fipple) so I don’t have the sort of problems you describe.
Another approach that suggests itself, is to use a smaller cutter and make several passes. Lower tip velocity = lower impact at given RPMs, and the finer cut is going to have less of a tendency to snag things.
Finally, if you’re using TiN coated cutters, deep-six 'em and go to plain HSS for brass. TiN dulls the edges ever so slightly, due to the plating process. You can see this dulling effect quite well with a 20X loupe. I had some issues with hanging swarf using TiN coated mills, and solved the problem by switching to HSS. That stuff barely notices brass, anyhow, and will last just about as long as the TiN-coated, without the problems.
Hope this stuff is of some use to ya!
Cheers,
Bill Whedon
Imperial tools makes tools for all materials of tubing. I’ve had best results from talking to a rep. and explaining the task. They are normally happy to provide options.
http://www.newmantools.com/imperial/ or
http://www.medicalgas.com/PDetail1.html or
http://www.go2marine.com/frameset.jsp?servletPath=/g2m/action/GoBPage/id/30491F/&df=3