HI, I am going to be adding a couple of additional tubes to my chassis but I need to use round tube, it will be welded at an angle on to the side of other round tube so considering how to cut the arc in the end of the tube to get a good close fit before welding.
Does anyone know a source for a grinding bit or tool to make this easier?
Cheers
Mark

Do a search for a shareware program called tubemiter, very good for marking the tubes and then easily ground out with an angle grinder and tidied up with a file.

Mick

Or you could get your self a 'Bird mouth' cutter, try looking on E-bay U.S. for them

Jason

Get tubemiter.

Cut a two 45 degree cuts with your hacksaw and fileout.

Pat...

And the instructions:

I think someone should make something like this and do it for everyone at a small fee:
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quote:

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Originally posted by Avoneer
I think someone should make something like this and do it for everyone at a small fee:

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quote:

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Originally posted by Deckman001
Or you could get your self a 'Bird mouth' cutter, try looking on E-bay U.S. for them

Jason

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Maybe, I don't have one, a friend told me about them, so maybe the name got lost in tranlation from waddon to South Croydon !!

Jason

Here's a low-cost alternative, if you've got a drill press. Looks like it'd take a little bet of setup, but then you could quickly cut out the ends as needed.

http://texaslocost.homestead.com/Suspension.html

Thanks for all the ideas guys

I used my Piller drill with a hole saw, ended up bending the morse taper that held the chuck when it snagged. I failed to grip the tube firmly enough, mind you its was 2" scaffold pole. Take care and use lots of lubricant.

Don't mess around... just use tubemiter or similar, make a paper wrap, glue it on (3M spray adhesive works a treat), and whiz it out with the angle grinder. A 1.6mm disc can cut remarkably close to the line.

I build cycle frames for a living and do a couple dozen joints like this every week. Hole saws are difficult to use, tend to rip the thin walled tube, and involve too much setup for just a couple of joints. We've tried jigs like the one Avoneer showed, but holding the hole saw steady enough for a nice clean hole is difficult. They're just not meant for this sort of application, but they work well on heavy walled pipe. A big lathe with a milling cutter can work, but it's even more effort to set up and cutters aren't cheap. The proper machine for the job is a tube/pipe notcher like this:
(we just got one at work) but you need to do a few hundred joints to make it worthwhile.

Yeah, will be going that route, just a bit more control than the hole cutter.
Cheers

quote:

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Originally posted by Deckman001
Or you could get your self a 'Bird mouth' cutter, try looking on E-bay U.S. for them

Jason

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I mark the ends of the tube and then put the form on with a die grinder with a carbide cutter in it.

The chop saw method, if understood, is a science. With known tube size and joint angle, tube can be notched with great accuracy. The notch is achieved by cutting two opposing angles on one end of a piece of tube, to form a point. The cross-section of this cut will be an elliptical cut due to the shape of the tube. Changes in both of the two angled cuts must be made for the intersection angle and the size of the two tubes being joined. The only real limitation is the max angle of the chop saw.

You start with what I call the base angle. This is the angle of both cuts if the joint was 90*. For an example, I am fitting Two tubes together that are both 1.75", at an 90* joint. The base angle, or the angle of both cuts is 28*. These two cuts must meet at a point, and the point must also be centered on the tube.

What if I want a 15* joint with my 1.75" tube???? You must start with your base angle, which was 28* for 1.75"(remember above), and subtract 15* from one cut, and add 15* to the other cut to form a perfect notch. So now I must make a 13* cut and an 43* cut with the point centered on the tube. Perfect coped joint, with no grinding.

Remember your base angle will change with the tube being cut and the tube that you are fitting to.

Here are a few examples of base angles...

2.0" to 2.0" tube, base angle of 30*

1.75" to 1.75" tube, base angle of 28*

1.5" to 1.5" tube, base angle of 26*

1.25" to 1.25" tube, base angle of 22.5*

1" to 1" tube, Base angle of 20*

Now to fit different size tubes together

1.75" to 2" tube, base angle of 25*

1.75" to 1.25" tube, base angle of 45*

1.25" to 1.75 tube, base angle of 20*

1" to 2" tube, base angle of 12*

Thanks Tim

One for the future

Mick

A good quality round grinding wheel of the same or smaller diameter as the curve required will do the trick! As already mentioned remove as much as you can with a saw or angle grinder, and finish off with the wheel.
Cheers J&J