Board logo

compound mitre joint
mars103 - 13/9/06 at 04:09 PM

hi

Im trying to make thee front assembly for the chassis,

how the hell do you cut those joints well?

ive heard rumors of paper templates on this forum, if someone could send me a link it would be greatly appriciated

cheers

Matt

MikeRJ - 13/9/06 at 04:47 PM

Mark the tubes using a scriber etc and cut one side at a time with a hacksaw, rather than trying to cut all the way through at once.

zetec7 - 13/9/06 at 05:11 PM

I used a cheap horizontal bandsaw, set up the angles carefully (to the blade, not the fence of the saw), and cut. My angles worked out perfectly (mind, I used McSorely plans..).

mark chandler - 13/9/06 at 06:45 PM

Wrap a bit of card around the tube and use this as an extension.

Cut with sissors, when you have the correct angles just slide up the tube and mark the metal, voila !

When you make the rear hoop stays this technique makes cutting the fish mouths out really easy

Regards Mark

big_wasa - 13/9/06 at 06:49 PM

I marked each face as above

mistergrumpy - 13/9/06 at 06:59 PM

I've just spent 3 and a half days trying to reckon these out. In the end I used a paper model of non-specific angles to get my head around what it should look like then I tried on bits of wood and then in the end I marked the metal as the final cut should be then cut each face separately and finally filed it down to fit a jig I made. A complete bastard of a job and I reckon it still has a bit of a twist in it after the fannying around I've had today!

kb58 - 13/9/06 at 07:46 PM

It's amusing how everyone says square tubing is easier, but after a couple of the above jobs I think that impression is challanged. My chassis contains both round and square, and the round junctions are easier IMHO.

MikeRJ - 14/9/06 at 08:46 AM

quote:
Originally posted by kb58
It's amusing how everyone says square tubing is easier, but after a couple of the above jobs I think that impression is challanged. My chassis contains both round and square, and the round junctions are easier IMHO.


If you have the proper tool for fishmouthing it might be easier, but if only equipped with a hacksaw, file and angle grinder give me RHS any day! In fact if you are accurate with marking and cutting, you only need a hacksaw.

Alan B - 14/9/06 at 04:14 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by kb58
It's amusing how everyone says square tubing is easier, but after a couple of the above jobs I think that impression is challanged. My chassis contains both round and square, and the round junctions are easier IMHO.


If you have the proper tool for fishmouthing it might be easier, but if only equipped with a hacksaw, file and angle grinder give me RHS any day! In fact if you are accurate with marking and cutting, you only need a hacksaw.


I agree with KB here on this.
Of course Mike has a good point about the tool, but a fishmouthing tool is actually quite inexpensive.

Square tube is pretty good for single plane (2D) construction but can get harder for the compound angle stuff, and lead to really ugly joints (if even if well executed) due to the cut tube's footprint where it meets the other tube causing overhangs. This isn't a problem with round tube.

Just more food for thought.

leto - 14/9/06 at 05:40 PM

mars103
If you can't find it I can make one. Do you want it “By the book” or any derivate, like McSorely or shorter J?

I use another technique for cutting compound angles, see post 8 in this thread.

lexi - 16/9/06 at 05:34 PM

Thank God I`ve done all that and got on to a lot of the other Bastard jobs that lie ahead of you
Alex

mistergrumpy - 16/9/06 at 05:56 PM

Its not over yet. You'll find two more to do on the back and at least two on the transmission tunnel.