Tube Notcher

[Mark]

A while ago, you used to be able to buy a very simple tube notcher from the likes of Northern Tool.

Northern Tool stopped stocking this a while ago, but it would appear they are now available from Frosts: Tube Notcher

Just thought I would post up the link in case anyone was after one, and was struggling to find them...

Mark

[moose]

Other notching methods are using chop saw/band saw

chop saw notching 101

which has the advantage of being able to notch very thick wall tube

this is 7mm wall dom (I used for trailing arms...) cut using a band saw

for more complex nodes where you have lots of tube joining at a point a cool little tool is a "contour gauge" like this expensive but could prob be done home-brew using welding rods threaded through a large elastic band....

[Orgasmic Farmer]

Now I am liking that contour gauge. Must surely be possible to knock up something similar for occasional use.

[L19MUD]

If only I had seen those contour gauge's before I did my cage!!!

[gibbon]

Not a fan of the contour gauge, as this works a lot lot better and its free.....!!!!!

Online tube coping calculator - link here

[Dave W]

I do something similar to the contour gauge with a piece of thin card. wrap the card around the outside of the pipe to form a tube and tape it up. Slide the newly made cardboard tube forward to meet the tube to be welded to and trim with a pair of scissors/sharp knife until it fits snugly, slide it back up the steel tube and you can then mark the steel tube by drawing around the cardboard.

A bit more faff than the contour gauge but "free" and once you've done one joint at that angle you can keep the card tube as a template for similar joins.

[missingsid]

I do something similar to the contour gauge with a piece of thin card. wrap the card around the outside of the pipe to form a tube and tape it up. Slide the newly made cardboard tube forward to meet the tube to be welded to and trim with a pair of scissors/sharp knife until it fits snugly, slide it back up the steel tube and you can then mark the steel tube by drawing around the cardboard.

A bit more faff than the contour gauge but "free" and once you've done one joint at that angle you can keep the card tube as a template for similar joins.

How about a mod to this, still fiddly but get a bag of wooden kebab skewers and stick flat on a strip of tape. Roll it up around tube then move forward until it touches. Now move each skewer up until each touch.

This requires an easy movable glue on the tape.

Other variations may work.

Marc.

[zim]

We use one like in the first post.

Bought on usa ebay for about $20. Replaced the bolts that hold it together as they were as strong as chocolate !

It's still working 3 years on

G

[simonr]

How I would make one of those contour gauges is to buy one of the ordinary linear ones for £2.99 and take all the pins out.

Roll / find a piece of tube just bigger than the roll cage tube. Then wrap rubber pipe round that and secure with a jubilee clip. Thread as many of the pins as possible between the rubber and the inner tube. Adjust jubilee clip for a suitable amount of resistance to the pins moving.

Si

[minimog]

chester tool company do a tube notcher

or you could use this copping paturn designer in this link http://www.metalgeek.com/static/cope.pcgi

its very good just type in the size of tube and the angle then print out the paturn wrap around the tube then cut

[neb]

Has anyone found any decent holesaws for the notchers, nice and deep ones?

[minimog]

i only use starret ones they last a lot longer than the cheeper brands

[zim]

I use starret, with the little teeth (not the big + small teeth). Can get them for decent prices on ebay.

G

[simonr]

I had a bit of an idea for a notcher for use with a plasma cutter!

It's a bit difficult to see how it works - but imagine the tube you want to notch threaded through the middle of the two halves.

The bigger diameter collar can be adjusted to the notch angle +/- 45 deg in this case and locked with a screw (not shown). The bit inside the collar is also locked to the tube with a screw.

The part on the right has a tube attached through which you poke the plasma torch nozzle. This is free to rotate around the tube. You rotate it, keeping pressure against the outer collar and it cuts a path defined by the profile of the collar - thus notching the tube!

©PSI Design Ltd 2011 !

Any thoughts?

Si

[CwazyWabbit]

That's really neat, I'm guessing the depth of the wave on the profiled guide is half the diameter of the tube it's designed to notch? A clever and simple idea that should be relatively cheap to produce, obviously a different one would be required for each diameter of tube you wanted to notch.

How much clearance would there need to be between the collar and the tube to allow it still to rotate and also make allowance for differences in tube batches and the expansion from cutting heat?

[simonr]

That's really neat, I'm guessing the depth of the wave on the profiled guide is half the diameter of the tube it's designed to notch? A clever and simple idea that should be relatively cheap to produce, obviously a different one would be required for each diameter of tube you wanted to notch.

That's the biggest down-side - needing a different setup for each tube diameter. You could use spacers for the two main components then just a different collar.

You're right about the collar - its just a sinusoid with half the amplitude of the diameter of the tube being notched.

At a pinch, you could use the tube notching calculator linked above to produce the profile, cut it out of card or a coke can and tape it on to a flat ended collar!

How much clearance would there need to be between the collar and the tube to allow it still to rotate and also make allowance for differences in tube batches and the expansion from cutting heat?

I've allowed 2mm - though it could probably be a bit less.

I figure the Collar can just be laser-cut out of thin walled tube making it fairly inexpensive. For a Prototype, I can use my 4th axis!

Si

[CwazyWabbit]

On the prototype if you split that collar you could use a couple of bolts to close/open up to adjust the clearance to find which works best. If it's too sloppy there may be a tendency to twist the collar sideways as you finish the cut as the support of the scrap piece is lost. With the cut being hidden by the collar it may be hard to 'prepare' for the loss of support as you forget where the end of the cut is. Maybe just a longer collar would solve the problem (if it even exists, just hypothesising here, too early in the morning for long words really )

[moose]

Looks like a very good idea i would have one.

Go on build it and then see if you can do this with it

[CwazyWabbit]

Looks like a very good idea i would have one.

Go on build it and then see if you can do this with it

At least two of those pipes have had bits welded on .... so not perfect then Must've taken a lot of fag packets to work all those angles out

[mickeyw]

Looks like a very good idea i would have one.

Go on build it and then see if you can do this with it

That's very elaborate for a gazebo frame

[simonr]

Go on build it and then see if you can do this with it

Tell you what, you could do that with it! If you use the CAD to work out the profiles for the ends of each of the tubes, print them out and make your own collars out of a coke can & scissors.

I have a feeling that big nests of tube like that are just showing off - but on the whole unnecessary, for roll cages at least. I'd be worried that you were concentrating too much stress at one point rather than distributing it a bit. You don't want a single point failure to make the cage useless.

For the short term, I've bought a roto-broach tool on ebay to mount in my existing notcher. Hopefully it will last longer than the hole saws seem to!

On the prototype if you split that collar you could use a couple of bolts to close/open up to adjust the clearance to find which works best. If it's too sloppy there may be a tendency to twist the collar sideways as you finish the cut as the support of the scrap piece is lost. With the cut being hidden by the collar it may be hard to 'prepare' for the loss of support as you forget where the end of the cut is. Maybe just a longer collar would solve the problem (if it even exists, just hypothesising here, too early in the morning for long words really )

I'm obviously being a bit slow today - but I don't understand splitting the collar!

I see what you mean about the twisty bit being unsupported at the end of the cut. One could fix that by extending the tube on the twisty bit (the bit on the right) so it overlaps more at the max cut angle.

Si

[CwazyWabbit]

By splitting the collar I just mean cut a slit along it's length, then weld a flange either side of the slit so you can bolt through them.

So it makes it like a clamp that holds a pipe.

By putting two bolts through the flanges you can reduce the diameter and if you use a third bolt through one flange (between the other two bolts) and pressing against the other flange you can increase it. .... I probably need to do a drawing...

Edit: By collar I mean twisty bit aka the bit on the right

[simonr]

Ah! I understand! I assumed you meant the collar With the wobbly profile cut in to it on the left

However, it gives me an idea! If you made the profile collar a bit more chunky with tapped holes for the pivots, you could wind a bolt in on either side. On the ends of the bolts, use a V shape which grips the tube. That makes it more adjustable for different tube diameters and means it could clamp a tube with a bend very close to the end. It also means the follower bar on the left can be shorter and the profile collar can achieve a sharper angle for a given diameter. It's also cheaper to make.

When you cut a slot in a tube, the diameter tends to close up. For the adjustable bit, it may be enough to have a thread cut in one flange for a bolt to press on the other flange to open up the tube a bit.

I'll see what tube I have lying around and try to make a prototype!

I bought a Hydrovane 5 compressor for the workshop. Boy, what a difference it makes to the plasma cutter! With the cutter running, the compressor runs almost continuously - but it now makes a decent cut in 10mm plate where before it only managed 4mm.

Si

[simonr]

Don't try this at home folks - it didn't work all that well!

I spent the weekend prototyping the idea and found several problems.

Firstly, as you are cutting, it leaves some slag on the top surface which stops the twisty bit the torch is attached to from sliding / twisting. If you move the torch away from the collar, friction between the collar and tube being cut becomes an issue. Make a PTFE liner for the collar - it moves more easily but even PTFE just melts.

Add little bearings as wheels to help the collar rotate - and it will not slide up & down. Make six tiny caster wheels using bearings to support the collar and discover it's still very difficult to get the pointer to follow the profile as some of the angles it has to climb are very steep. Put a stack of bearings on the pointer, still little better.

Give up, go to pub!

Hopefully my rotabroach cutter will turn up soon - and I'll see how well that works compared to a hole saw.

Si

[simonr]

I gave in and bought one of these: Baileigh Notcher which turned up this morning.

I wasn't expecting it to be much better than the one I bought a few years back (which was a bit rubbish, but did the job). The Baileigh one however is really solid! It weighs 10kg and is rigid as hell with nice bearings. I've also bought a cheapo 'Mixer Drill' which runs at 800rpm and should be slow enough not to cook the hole saws. Running the saws too fast is the biggest problem with most drills. My DeWalt Battery drill goes plenty slow enough - but the battery only lasts a couple of notches.

Although the Baileigh Notcher is pretty expensive - I think it represents very good value. The old one can live in a dark corner where the Mice can play with it!

Si