cheaper way to machine miter?
a number of companies make these things they call "tubing notchers" which are essentially a drilling jig for use with a hole saw, that holds the tube at an angle and drills vertically. you can clamp it to a drill press or they say the preferred method is just clamping it to a workbench and using a hand drill. there are also framebuilding-specific "mitering machines" but these are a lot harder to find than the "tubing notchers" which are marketed for things like building race car frames.
eastwood makes what seems to be the highest quality tubing notcher. i asked them and they said it will work fine with thin wall cromoly tubing. the angle range for that one is 30-90º. there's a link at the bottom of my post.
what i'm wondering is if anyone has heard of these being used for mitering tubes for framebuilding and whether they are rigid enough for the task.
i know...the ideal setup would be a vertical mill and some high-quality hole saws (more than $100 each), but i'm wondering if one of these "tubing notchers" and some cheaper hole saws (along with plenty of cutting oil) would be rigid enough to prevent bad cuts or lots of broken holesaw teeth.
here is the URL for the Eastwood one:
If you are just building a few frames find the tubemiter.exe program. Those cheap notches are not very ridged and not worth the money in my opinion.
Older I get, Better I was
"cheaper way to machine miter? "
A 10" half round ba$tard file.
Every time I see someone mention tubing notchers and building bike frames, it's always negative. Not precise, have to be aligned/shimmed, won't hold thin tubes tight enough without crimping, etc.
+3 for the vise, block, and file method. You can hand cope a tube just as fast or faster than you can set up a notcher, mill, whatever.
A mill would be nice to have for other things though...think of the stuff you could make!
agreed.. a mill would be useful for sure. and you're right about the setup and actual mitering taking just as long or longer than hand-mitering. a mill could be nice because once you had something set up you could make that same cut a bunch of times (i.e. small scale production, or whatever). it would also be handy for those quick 90º miters that could be done by hand pretty easily too. maybe it would shave off a little time. imo not worth the cost unless you are larger scale and/or also use a mill for other stuff, like machining your own jigs or fixtures.
Originally Posted by SamHall
good point on the crimping thin-wall tubes thing. i asked eastwood about that awhile ago but i doubt they realized quite how thin i was talking about. also i think if you could do all your miters by machine for under $300 it would have caught on by now. seems like these tubing notchers are not worth the headache.
Yes, i'm aware. my post was about machine miters a.k.a. mitering by machine, not by hand.
Originally Posted by velonomad
Older I get, Better I was
Someone had to be the wise***** It was my turn
Originally Posted by coyotecrust
But seriously I have a drill drive notcher , It work fine for mild steel tubing over .049 wall. I used one for building cage karts a few years ago when my son and I were racing. But these wear quickly and soon the cuts go off center. Best success I had with thin wall tubing and the notcher was using a carbide grit holesaw from LS Starrett. The hole saws were $40 each
Best cheap set-up for precision tube coping I have seen is a Grizzly combo mill (vert and lathe) The Grizzly new goes for around $1k.
Another vote for the hand miter, at least until you can afford a good mill. I haven't had much success at all with notching tools whether driven by a press or a hand drill. In point of fact, all such miters have, at least for me, required a fair degree of touch-up with the aforementioned file. So between set-up and touch-up, I found the notcher to be slower than the file.
3 features of 4130 and similar chromo tubing
- So thin it is cutable with aircraft snips, so in larger sizes you can rough out the metal with "scissors"
- So thin it files incredibly fast
- Nice clean cutting material ideal for fast filing
I agree with comments above that unless you have a production need, hand work is actually faster. Sometimes a craft gets burdened with stuff like Bridgeport mills just because an early prominent book writer, or whatever, was a machinist by training. The old story about if you all you have is a hammer everything looks like a nail. A Bridgeport is to bike building what a nuke power plant is to boiling water.
On the other hand, these days, machine tools are going so incredibly cheap, it's hard to pass them by, grab them while you can, this is a once in an earth time opportunity. A burke horizontal mill sat for a week or so on Practical Machinists buy and sell forum at 400 bucks!!!!! Unbelievable.
So no mater how you look at it, this use doesn't really seem to cry out for a jigaroo.
"you can clamp it to a drill press"
That's kind funny really, if you think what a drill press is it's basically a milling machine for on end drilling type milling which is exactly what is called for here. When people try to turn milling drill presses into mills (see articles in current issue of Machinist's workshop, or either of several videos on the subject) The main grip is side loading the bearing, which isn't happening here. The only missing part is at most a vise that is x-y positionable which is a relatively cheap chicom accessory. I've been thinking on the problem about 60 seconds, and I think I could position the tube for drilling in a fixed vise with nothing more than a single dial indicator, or moveable stop, so even the X-Y table probably isn't necessary.
I think part of the reason why people use the big expensive stuff on these kinds of jobs is that they can't think their way around a simpler set-up.
If you are going to use hole saws, you don't so much need the expensive Strawberry saws, though I have heard in the long run they last so long they pay for themselves, what you do need is something like a threaded MT for your drill press or possibly the Paragon unit that mounts hose saws, both under 10 bucks. These take all the wobble out of normal arbours, some of which are designed to function bare handed or not ket plugged with the wooden offcuts, moreso than desiver concentric holes the same diameter as the saw.
Then you need to track down a hole saw that cuts to the right size, and keep in mind the tubing mouth can be flared to make it slightly bigger or smaller, and this is perfectly respectable. though not workable with lugs.
Also, Strawberry or otherwise, if you think through your method, you may be able to get your cutter order down to 2 for the major cuts in the bike, which really isn't unreasonable. I remember one post a while back where a guy wanted to buy about 5 of the Strawberry hole saws, until someone pointed out you mostly only need two sizes (assumes 1.125 stems).
Also, to be a triffle pedantic, going back to the "cheaper way to Mill" part of the title, I wouldn't call what those jigs do "milling". While a lot of workers find the graduated angle scales and bearings reasuring, it's not anything like the accuracy potential of machine shop tools (including a drill press). And.. they don't call them "mill" files for nothing.