Is there a way, or a jig, to make a tube miter joint with a die grinder?

The last ones I did was with a hand file. Takes a long time.

I'm sure a creative person could make a tube miter grinder using a die grinder as the basis. But not me. However there are ways to quicken up hand mitering. bench grinding to a scribed line to miter to is a way to get close to a miter fast. I do this usually for the main tubes. If you don't have a lug or shell that you can slide the tube into, and then scribe inside of, you can make a miter scribe guide. Take a tube that slips over the main tube diameter (.125" larger diameter with a .058" wall) and miter the common main frame angles for the diameters or shapes by any method that works for you. Then the next time you need a miter about the guide's angle just slip it on and scribe away. Then notch out the bulk of the miter with a hack saw and grind the rest to the line. This cut and grind to a line should take all of a few minutes. The fine filing to the ultimate angle and shape will go faster with a good roughing out.

With a little practice basic single tube joint mitering shouldn't take much more then 15 minutes. With a lot of practice half that time. Andy.

what about a tube mitering jig? wont that cut the time to almost nothing at all?

I use an electric drill with a 1/2" chuck, a tube notcher from Harbor Freight, and different diameter holes saws. After the cut, all it takes is a little cleanup with a file to get a near-perfect miter.

I tried one, the Joint Jigger. But i found the slop in the spindle's bushing and the tube clamp's small contact made for wondering angles. My jigger was also not centered. I shimmed the bushing to get better on center but still dislaiked the tube clamp. I see that Stan uses a reinforcing sleeve on the tube. I still have mine although I've not used it in a long while. It was faster then mitering on my 6" Atlas lathe but with more chudder and tooth catching potential.

The only machine mitering that I've used that was really nice was Doug Fattic's mounted on his Bridgeport mill. It uses a collet to hold the tube and is VERY rigid. Andy.

If you have good files it should be quick. The original way miters were cut was with aircraft shears you can waste a lot of the miter that way, and then there is only a small amount to file off, but the guys who use files on bike tubing don't seem to bother.

around 2:00

https://www.youtube.com/watch?v=KIxCdTRkRHo

You can do the hacksaw bit with shears, on the kind of tubing we use. Not the BB or head tube, maybe, but then they receive miters.

Andy, I did have to experiment a bit to get the right drill speed, feed pressure, and lubrication to minimize the chatter, but eventually seemed to hit the right combination. The other thing that helped is using quality fine tooth (10 teeth/inch) hole saws instead of the cheapie in the photo.

I hacksaw. The filing part takes practice, once you get practiced, it should be relatively quick

I cut the rough shape with an air cut off wheel

Then get as close as I can to the line with an angle grinder. Its really easy to finish it up with a file after that.

Yeah, you can actually cut through the lines really well with a dremel. Sounds like taking a boy to do a man's job, which it is to and extent, but it cuts like nothing is there. The bad part is the little discs are fragile. And of course there is dust. But that is where the snips are good, they cut without any of those problems, though I have no idea what they would be like on some of the upper end tubes, works great on 4130.

Oh yeah, at one point I was looking for some info on grinder wheel explosions, the big vitrious wheels, for a safety demo. By the way, you can grind tubing out on those also. Anyway, despite all the nagging about how unsafe those wheels can be I didn't find much in the way of information, though I did find some accidental death stats. What I did find was photos of the most gruesome imaginable accidents with cut-off wheels. Heavens! If you are into that kind of thing, what a rich resource.

if you get reinforced wheels, they are pretty robust. I get mine from McMaster

Stan, Where did you get your hole saws? I bought some from this site https://syncnotcher.com/twits/ as well as some thin wall tubing supports (which I really like), but the saw's are fairly out of round. I'd like to find something better. Thanks

BTW, I use the Harbor Freight notcher as well. Had to shim up the clamp to center the saw, and when using the tubing supports it works out pretty good.

I had read that the center of the spindle was likely offset from the tubing clamp "V" bottoms, so I carefully measured both from the body (base plate), and they were the same. When I mitered my first tube, it was dead centered, so I guess I lucked out on mine.

The hole saws I bought were Rock Hard brand type SCF Bi-Metal 10 teeth per inch. They were running out when I bought mine a couple of years ago, so I don't know how their supply is. I'm strictly a hobbyist, so I'm using them infrequently and so far I've had no broken teeth.

From the current Missouri Precision Tools on-line catalog:

"Fine Tooth - 10 TPI Bimetal Hole Saw, 1-3/8" depth

We've gathered up all the Fine toothed hole saws from all the warehouses, and have limited numbers of limited sizes.

For fine cuts in metal sheets and are particularly recommended for cutting tubes as sudden stoppages due to binding are greatly reduced.

Our customers have repeatedly praised the concentricity and smoothness of cut when used to notch tubes for miter joints for tubular construction of bicycle frames, custom auto frames and aerospace fabrication."

Here are the two Rock Hard catalog pages:

excellent thanks

apparently the quality on those went way down leading up to the company going bankrupt.

I read that on another site (one poster said that recent Hard Rock hole saws were "crap"), but didn't see it anywhere else. Mine are a couple of years old and I haven't had any problems.

all I know is that mine were nothing special, whereas I bought them because of all the praise. I would say you can go to a borg and buy Lennox that would work just as well

All this talk about miter cutters got me to try to put my Jigger back together. I haven't yet found all the parts... Andy.

Here's the Harbor Freight Notcher Manual (pdf).

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OP & Andrew; I recently had to replace almost all my original frame making tools, files, torches, frame jigs, etc., (as well as adding an alarm system to the shop). I went back and forth and did a lot of research on mitering tubes. In the end I selected this kit (JD2 Notch Master, TWITS, Snap Collars, and a initial set of saws to be replenished as needed);

The JD2 Notch Master has a heavy duty 1 1/4" thick steel frame and a polished 1" stainless steel shaft running on double sealed needle bearings. So far I have not been able to find any slop in it at all, but it runs buttery smooth. It is also really simple to setup and use. The old $50 unit I had used for quite a while is a wobbly, inprecise tool in comparison.

Find the JD2 unit through Amazon ads or directly here; https://www.medfordtools.com/notchmaster.html

Here is a pix;




Medford Tools and Supply Order
-----------------------------------
Item Ref. Price ea. Qty. Description
101200 $279.00 1 Notch Master Tube Notcher <<<<<
T-WITS-19 $19.95 1 3/4 TWiTS
T-WITS-25 $19.95 1 1 TWiTS
T-WITS-29 $19.95 1 1-1/8 TWiTS
T-WITS-32 $19.95 2 1-1/4 TWiTS
SYNC-SCL14K $ 89.95 1 Snap Collar 14pc Tube Kit
SYNC-SCL114T $ 9.95 2 Snap Collar 1-1/4 Tube
BIF-16 $ 9.95 1 5/8 fine tooth hole saw
BIF-19 $ 9.95 1 3/4 fine tooth hole saw
BIF-25 $10.95 1 1 inch fine tooth hole saw
BIF-32 $10.95 3 1-1/4 fine tooth hole saw
BIF-35 $11.95 2 1-3/8 fine tooth hole saw
BIF-38 $11.95 2 1-1/2 fine tooth hole saw
BIF-44 $12.95 1 1-3/4 fine tooth hole saw
BIF-51 $13.95 1 2 inch fine tooth hole saw
LEN-30857 $3.95 3 Hole Saw Adapber 1/2x20 to 5/8x18

Hope that helps OP

/K

How funny is that. I drive past Medford Tools every single day to work and have been looking for a tube notcher. They always ha e catch religious sayings on their billboard that make me chuckle.

I found that doing business with Medford Tools was a delight. Fussy attention to details and customer support, reliable pricing, and quick well packed delivery. I do remember the shock when that Notch Master arrived. I seemed to weight a ton... or darned close to it. I used a wheel cart to run it down to the shop so I would not have to carry the box...

I'll have to stop and check it out on my way home from work. Not to mention I've got a Xmas bonus coming from work.

I use hacksaws and files with paper templates. Once the template is on the tube, it takes about one song on the radio to do all the cutting and filing.
The paper templates work great for round tubes but I don't know of any for oval shapes like chainstays. I score the stay inside the BB shell then start cutting.
Does anybody hand file odd shapes like chainstays mated to a socketless BB shell? Do you eyeball it or is there a good trick? I haven't had a reason to do that yet, just wondering.

there are templates for chainstays too. It's a little more fiddly to fit them, but not that big of a deal. Well, it is a big enough of a deal that I have considered making a fixture to cut them on my lathe.

I like the template method even though there is a vocal contingent of framebuilders that insist you should be able to do it without them