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binfordw
05-11-2010, 04:56 PM
Hi,

I need a small bender. I want to cleanly and accurately bend up to 3/16"x 6" plate to 90deg. I can't seem to find a low cost solution really. Most all benders/brakes I find only rate what they can bend in full width, i.e 18gax 24" or similar.

Anyone know what I can use?

Thanks

camdigger
05-11-2010, 05:03 PM
At 3/16" thickness you're out of the sheet metal brake territory and up in the press brake territory, IMHO.

A tubular steel frame and a $40 20T bottle jack will do what you want.
http://i766.photobucket.com/albums/xx301/camdigger/PA251338.jpg

I've seen one that had the bottle jack underneath the bottom die pushing up with the upper die tied to the side rails too. That configuration allowed multiple bends much tighter than mine will.

CCWKen
05-11-2010, 07:29 PM
How many bends do you need to make? A few pieces of 2" angle iron and a shop press will do it but if you're making a lot of pieces, make something like Camdigger shows but use a wider lower die opening. The wider the opening, the less tonnage required to bend. It will take about 14 tons with a 2" lower die.

Black_Moons
05-11-2010, 07:35 PM
at 6" you might just consider a vise brake if you have a SERIOUS vise.
http://www.rv7plane.com/fuselage/files/fuselage199.jpg

Anything past 6" is rather outside its capacity.. but its pertty cheap/easy to make!
Not sure if it will do 3/16" however.. Might be a little too much to ask of a vise.

camdigger
05-11-2010, 07:45 PM
Bmoons idea might work with a wider die opening like Ken suggests.

Like most things, the answer will be related to what you have available already and what you are prepared to do and/or spend to make it happen.

I used to have a link to bending force requirements vs punch and die combinations, hmmmm, wonder where that went??:D :o

Editted P.S. Found it! have a look here for bending tonnages... http://www.americanmachinetools.com/pressure_table.htm

From the chart, 7 ga - 0.187" material with a die with a 1 1/2" opening and a punch with a nose radius of 0.187" will require 11.2 tons force per foot of width to make a 90 degree airbend - so 5.6T for a 6" width. If you could be content with the bend results from a 3" die opening, you could do the bend with a properly anchored 3T arbor press.

Mark K
05-11-2010, 08:33 PM
This might work for you...

http://www.lowbucktools.com/platebrake.html

Williams Low Buck Tools, Plate Brake.

Mark

binfordw
05-11-2010, 08:47 PM
Thanks for the tips,

I dont have any punch/dies anymore, I used to have a couple somewhere.. Anyhow I milled a 1/4 plate into a punch and then a V die, and started on a press frame for a bottle jack. It worked on a piece of 16 gauge well but I didnt mill the bottom die right, its too small for thicker materials.

I think when I get the punch die sized right it will work fine for what I need. I had looked on ebay for used punch/dies but didnt see anything "cost-effective" enough to buy. I guess milling some will be fine, its not like Im going to use them enough to wear them down.

Oh and very cool vise setup, I hadn't seen those before really neat!

DR
05-11-2010, 08:59 PM
Press brake capacity ratings are usually made with a lower die width of 8 times the material thickness.

8 times .187 is near to 1-1/2" die width.

As others have said, make a wider die to lower the required tonnage. But, a wider die equals larger bend radius which may or may not be acceptable.

Willy
05-12-2010, 02:00 AM
Timely post as I'm just in the preliminary stages of building a small press brake myself.

Camdigger, thanks for the link to the bending tonnages and how it relates to die width and or spacing, just what I was looking for. Good looking brake you built, I remember seeing it in the other press brake post, I like!

Black_Moons, I like your vise mount brake, just right for the smaller jobs. I have seen them before but can't remember where I saw one last, where did you get yours?

Black_Moons
05-12-2010, 04:32 AM
willy: I don't have one, but I have seen them at KMStools and ebay.

garagemark
05-12-2010, 06:47 AM
Camdigger, do you have a couple of "rough" dimensions for your press brake. My monitor is so shi*** y that I cannot see the die area very well. Is it a straight wall or does it conform to the punch profile.

I like it... I must have one like it...

Thanks,
Mark

GKman
05-12-2010, 08:55 AM
For the die, I just stood a couple of pieces of square stock on one corner and welded them to the base plate. Make the included angle about 80* to allow for springback. Ditto on the punch.

http://img.photobucket.com/albums/v494/gkman/P2200041.jpg

camdigger
05-12-2010, 11:10 AM
Camdigger, do you have a couple of "rough" dimensions for your press brake. My monitor is so shi*** y that I cannot see the die area very well. Is it a straight wall or does it conform to the punch profile.

I like it... I must have one like it...

Thanks,
Mark

The lower die is two lengths of 3/4"? rod skip welded to a short piece of wide flat bar. IIRC, I spaced the rods aprt with a length of 3/8" material.
The thread that has some of the details of my press brake is here.http://bbs.homeshopmachinist.net/showthread.php?t=37212&highlight=press+brake