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michael3fingers
07-11-2010, 07:28 AM
hi all

I have just about finished my HMP 200 bender. I am about to start on the dies.

I was just wondering why most bending dies are only about a little over 1/4 of the full circumference?

Having the option to make my own I can increase that considerably providing I leave some room for the thing that draws the pipe through.

Wouldnt more of a circumference allow me to bend close to 120 degrees, maybe I want to build a trombone or something...

thanks for any responses I may receive.

DR
07-11-2010, 11:48 AM
hi all

.................................................. ..................................................

I was just wondering why most bending dies are only about a little over 1/4 of the full circumference?

.................................................. ..........................................

.

My guess is you've been looking at low cost, poorly made dies.

The dies I'm familiar with are basically half the pipe/tube circumference.

Arthur.Marks
07-11-2010, 01:05 PM
Any good die I've ever seen is equal to radius depth on the circular die. Then there is another section---such as in the case of the DiAcro bender design---that is also radius depth but straight. This straight portion is pulled over the rounded die on a tangent. The result is nearly 100% coverage of the tube at the point of bending.

If using a three roll bender, once again, use full radius depth. Any more doesn't gain anything. Any less is inherently less support on the tube and more likely to kink.

michael3fingers
07-12-2010, 02:29 AM
I think I am being misunderstood.

I know all dies have a concave half the size of the desired pipe tube what ever.

What I was asking was why are the dies not closer to 360 degree round?

From what I can gather to make a round die you turn a complete round and cut it into 3 pieces.

It just seems like a bit of a waste to only use 1/3 of the die when I could use maybe 180 deg and be able to bend past 90 deg?

this is an example of a larger radius
http://image.rodandcustommagazine.com/f/10613813+w750+st0/0811rc_07_z+tube_bending+mb_die_cheater_die.jpg

and this is a smaller example
http://favoriteprojects.com/bend_die.jpg

also can some one tell me the ideal pivot point in relation to the centre of the radius?

thanks guys

ecortech
07-12-2010, 09:48 AM
I believe with that type of bender, due to the geometry of the bender itself it not possible to bend much more than 90°. Also in any bender you can't bend past 180° or you can't get the die out of the completed bend. In practice most bends you will have to make, 99% of the time you will find that they are 90° or less. I can't actually remember the last time I bent anything over 90°, and I bend a lot of tube, for many different things.

Ed

Dawai
07-12-2010, 09:57 AM
http://img.photobucket.com/albums/v85/ibewgypsie/sscn1388.jpg
Hunk of metal to do a 180 die, costs near as much as the die professionally made. I bought them.. Now, they have went up about 30% tho.

Bending.. I used to bend sideways.. clearance.. NOW, I turn the bends upward..

GKman
07-12-2010, 12:43 PM
I have hand operated 180* benders for steel tubing. Have wondered if you could laminate the dies like a master padlock. A different radius milled in each layer and stacked up to aproximate the desired pipe diameter.

michael3fingers
07-13-2010, 02:16 AM
thanks erryone

It cleared it up nice.

Anyone chime in on the rough location for the pivot point.

I know it needs to be off center so it kinda levers the die around but by how much?

Most places on the net are bender plans heavy, and die plans light...

Once again thanks guys

ecortech
07-13-2010, 08:55 AM
Die assembly instructions here
http://www.pro-tools.com/pdf/HMP-200-HYD-DIE-ASSEMBLY-INSTRUCTIONS.pdf

Ed

DR
07-13-2010, 05:37 PM
.................................................. .................

Anyone chime in on the rough location for the pivot point.

I know it needs to be off center so it kinda levers the die around but by how much?

Most places on the net are bender plans heavy, and die plans light...

Once again thanks guys

Hmmm...........That's something that had never occurred to me. So, I went to the shop and checked a whole bunch of professionally made dies. The dies were all 180 degree for 3/4" tube with various radii. The center hole/pivot point was within .002" of being on absolute center in every one of them. The few thousands off from center was no doubt due to my quickly using a caliper to check.

What do you mean by the off center pivot levering the die around?

RussZHC
07-13-2010, 09:59 PM
DR: I think he is talking about the "pivot tab placement" in the earlier reference linked.

What has always had me wondering (mathematically challenged :o ) is how those tab placement numbers seem to have no specific relationship e.g. an inch change in radius, 6" to 5" moves the pivot
1 1/8" whereas a smaller change of radius only moves the pivot point
1/8".

DR
07-13-2010, 10:03 PM
DR: I think he is talking about the "pivot tab placement" in the earlier reference linked.

What has always had me wondering (mathematically challenged :o ) is how those tab placement numbers seem to have no specific relationship e.g. an inch change in radius, 6" to 5" moves the pivot
1 1/8" whereas a smaller change of radius only moves the pivot point
1/8".

Yeah, I guess I don't understand what he means. The bender I have has a stationary pivot point.

dsharp
07-14-2010, 12:15 AM
http://www.toolsforbending.com/literature.asp They have some useful literature.

Paul Alciatore
07-14-2010, 01:57 AM
I'm not familiar with this type of bender, but couldn't you bend 90 degrees then move the tubing 90 degrees around the die and bend another 90? That works with conduit benders.

As for removing the bent tubing from a die that was over 180 degrees, you could make a split die which would be disassembled and removed in two pieces. Seems like you could do up to 360 degrees that way.