tube notching / fish mouthing etc

[deadlikeme]

Hi all, just picked up my cage hoop for my ginetta and now need to sort the legs out.

Can someone help me in regards to notching the legs ready to weld onto the hoop top horizontal?

Looking for tips, advice, any machines I could build to aid the making, how to mark the pipe correctly before cutting it too sort but with a nice mouth lol

Cheers
Chris

[Minikidx14]

This is what you need A tube notcher

[dave21478]

If you don't want to invest $$$, look for a program called "winmiter".Its freeware and very basic, but works fine.

You input the diameters of tubes you are joining and the angle of the join and it outputs a template you print, cut out and wrap around the tube, which gives you the line to grind/file to for a good joint.

[deadlikeme]

yep unfortunately I only plan on making two maybe 3 max so cant justify a real notcher but that software sounds like a win win! I shall look it up, thank you for the tip!!

[Minikidx14]

Try this... www.harderwoods.com/pipetemplate.php

[cossie pop]

heres another

metalgeek.com/static/cope.pcgi

[caddygaz]

wrap a piece of paper round the tube and tape it up so you have a cylinder.

slide the paper off the tube.

flatten it.

line the the end of the paper up with the open end of the tube.

draw round the tube.

( at this point you should have a rectangle of paper with a circle drawn on it... )

next cut the circle exactly in half.

then cut out the semi-circle.

open the paper cylinder back up

slide it back onto the tube and draw round it.

remove the paper and grind to your line.

then keep offering it up and reaming the edge till it fits snug.

hope this helps. I'm not very good at explaining stuff...

this is basically what that programme does.

[Rich606]

That's alright if you're joining the tubes at 90^o, surely? Any other angle and it's rather more complicated.

[caddygaz]

this is true, but from the description of what he wants to do, i pictured it would be a 90 ( dint know how to do the degree symbol ) join.

[deadlikeme]

thanks for the comments so far guys, heres a picture of my drawing showing the angle needed on the cage. Ive just ordered a tacky angle finder of the digital kind from ebay so that help too.



the main hoop is at an 80 degree angle due to seat/head location and the rear legs are now going to so straight to shelf without the bend in, helps with forces and all that jazz.

[Clamity]

Dec 16, 2011 21:54:05 GMT cossie pop said:

heres another

metalgeek.com/static/cope.pcgi

I have used that one. Very simple and works great.

[deadlikeme]

Hey cheers guys and the pics are very helpful just to see it working

Chris

[da6t]

you can buy hand operated, guillotine style notchers, we use them at work, wouldnt be cheap though and no good for anything other than 90 degrees!! don't forget that your going to lose 8 or so mil off your length when you notch it, probably wont affect you but worth noting!

[chairchild]

After spending close to 3 days notching these tubes by hand.... I'd be damned grateful for something like that tool at the top!



We used a lathe with a cutting tool the same diameter as the tube we were cutting, but it just kept folding the tubes over if we went past 45 degrees

[Clamity]

Dec 23, 2011 17:16:47 GMT chairchild said:

We used a lathe with a cutting tool the same diameter as the tube we were cutting, but it just kept folding the tubes over if we went past 45 degrees

Interesting looking assembly in that pic. What was the wall thickness out of interest? I tried making a jig for doing this a long time ago by drilling out a short offcut of steel bar to make a doughnut shape and then boring a hole at the right angle into the side of it in a four jaw chuck on the lathe. The idea was you insert the tube and use it as a guide for a drill the right diameter. It made a right mess as the big pillar drill wrapped the tube round into a big knot and sent the vice holding it across the workshop. So don't do it that way

The tubes in my pics above are 3mm wall but took about 10 minutes each to do: chop out a V shape with a cutting disc, round it out with a flap wheel and finish off with a half round file. That online coping tool puts axial lines in at 90 degree intervals which make a handy guide where to stop cutting each side of the V. Would have thought the same technique would work ok with thinner wall tubes too.

[chairchild]

The main hoop was something around 3mm thickness IIRC, the rest is all 1.2mm. Most of them were a PITA to do, as each end were joining onto a joint of two other tubes, which were never in-line with any other cut you made on the tube, and each side had to be at different angles :\

Still got to do the front section, and the diff support section! Then build the suspension (after they've finally given us dimensions!) slap it all together, and hopefully, compete!

Lol, and what you did sounds like an industral tennis-ball thrower gone wrong;D

[phillipm]

I always just use a 4.5" grinder with ceramic flap discs for spaceframes, haven't found anything faster yet...

[Dez]

ive always found this method as quick and as easy as anything else when working with things other than 90 degrees. if its a simple 90 deg. joint i use the pillar drill and a hole cutter.

[grasser26]

Hi-What book or magazine is that info in? It looks very useful-and might go well with tea too!!

[Good Scrap]

theres a chap half way down this thread using a lathe and hole-saw for notching tubing

bbs.homeshopmachinist.net/showthread.php?t=39202&page=66



in-fact the whole thread is brilliant and inspirational to those who like to have a go at making tools rather than buying....