Manky Monkey Motors

I'm having a problem when bending the smaller 35mm dia,3mm wall tube that I'm using
to form some parts of the trike frame.

I'll try to explain, if i try to bend beyond about 30 deg the tube wrinkle's on the inside
of the bend and flattens on the outside making it look less that it's best and I'm finding
it hard to repeat bends because of this. Had no problem with the larger tube used for
the main frame.

The former I am using is 1 1/2" but it's the nearest that came with the bender

Hope that makes sense. Any idea's or comment welcome and appreciated

thanks

Eddie

Have you tried moving the rollers to a different position Eddie? The Clarkes benders have half a dozen sets of holes, so the rollers are adjustable. Moving them out further may help. If the tube isn't a good fit in the former it can also cause problems. Try packing it with aluminium, which will compress to the shape of the tube. I used a couple of cut up Coke cans when bending odd sized tube.

Thanks MM

That is the type of bender i have although not a Clarke. It does happen that I'm using the holes nearest to the pump
so i could try moving it out and see what happens and I hadn't thought of packing it might give that a go in the morning

1.1/2in is equivalent to 38mm or there abouts,I won't make any difference moving the rollers the former is much to big,As Andy said use a piece of ally plate about 1.5mm in the former this will take the shape offthe tube.

i have had the same problem with the heat pipe 33.7mm pipe using a 1 1/4" former is to small and a 1 1/2" is to big any tips would also be helpful as have had the same problem 

if you have any old roses quality street heroes chocolate tins are idea  for using as spacers as well

One other cause can be the type of tube. Is it cfs (cold finished)? When I tried bending some even with the correct former the outside flattened the inside started to wrinkle and it got stuck in the former. The only remedys I could find for this were, annealing the area of the bend or filling the tube in that area with lead (LMP bending metal would be preferable) neither of which are exactly cheap in gas but the lead method gave the best result. I now only use this type of tube in straight sections.
You should be able tell if it's cfs by the polished, usually blue black finish.

I've only ever used ERW, (electrical resistance welded), toob -steam pipe basically. Cheap & cheerful & available from Plumb Centre or most plumbers merchants. Perfectly strong enough in a properly triangulated frame, but soft enough to bend nicely in a Clarkes type hydraulic bender.

I find marking the tube in inches and a center mark then work your way along the tube each side off the center mark I tend to do 3 pumps per mark then move on to the next untill your happy with the curve
I did find if you try to bend strait away in one place it does kink a fair bit ,, im starting to find I cant bend any tighter curves because off the bender frame now its starting to annoy me now

Also I use cardbord to pack out the former its cheeper and more flexable

I have found that tring to bend with out moving the pipe after it reaches  the ark of the former it puts indents in the pipe i now move the pipe back and forward untill the desired bend is formed

Yup, there's definitely a knack to forming clean bends. Just takes a bit of practice.
Welcome to the forum Mixa.  ;)

Hi. here is what i do, work a treat.

• Seal one end with plenty of insulation tape.
• Stand it on end and fill it with water.
• Get a bucket with some sand in it and fill the bucket with water.
• Stand the tube in the bucket, so that any water you will displace goes back in the bucket :)
• Take the wet sand and SLOWLY add it to the top of the tube, so the sand will then settle to the bottom of the yube.
• Regularly tap the tube so the sand really compresses and settles.
• keep going with the filling and tapping until you can get no more sand in the tube.
• Let it rest, tap it some more and put some more in !
• Seal the open end with inssulation tape.
• Bend away!!!

Oh, and use warm water in this weather or you will get frostbite :)

This really helps a lot. I think the sand sort of converts the tube to behave more like a solid bar, or summat

Welcome to the forum

i bent todat 1 7/8" erw i have 1 1/5" or a 2" former, i new at 2" it would spread at ther sides so i used the 1 1/2" former it bent perfectly it only needed a tap with a rubber mallet to get the former off, also with 3mm wall 1 14" erw i found it better to stick to the ferthest outside holes for the rollers. and always have the welded seem on the inside of the bend ;)

** i take no resposability if you do happen to break you former doing this**

somebody ,shattered,, my 1 inch former  :o :o trying to bend high tensile solid bar  ::) ::) ::)

i had trouble with a bender once,so i smashed his face in. ;D

I went on a bender a couple of times, 1969 to 1973 and 1980 to 2001. :)

did he have a nice bum nabs  :D :D

How did you guess it was a he? Do you know Jack as well OAB.? :)

it was all ,jacks, fault  ;)

 ;D ;D ;D