Thread: building a pressbrake

I have been wanting a simple pressbrake for years, I find lots of old mechanical ones but very few hydraulic ones. I decided to build a closed sided press a good friend of mine built a 10ft open side press but he spent a fortune building the thing. I was looking at the press made by fab 123. It is made of plate and runs about 50 tons. I am going to build a 4ft press with maybe 40 to 50 tons I found a smokin deal on 4in hydraulic cylinders 50 bucks each they are 8 inch stroke. I figure that would put me on the lower end of 40 tons maybe mid 30s. Should I just suck it up and buy the 5 inch cylinders and get 50 tons and have any of you guys built a pressbrake before?

Tonnage is gonna be determined by what you want to doo with it.....

IIRC (without looking at the chart) 1/4" plate will require (with a standard
8x thickness die opening) 20 tons per lineal foot.

Your 4' press brake would require 80 tons if you want to run 1/4" plate, and
use the standard 2" die opening (min leg about 1 1/2").

Can you find a cheap mechanical and bolt on cylinders? Just a thought

These guys make a simple press brake with minimal castings or complicated machining.
Their 40 ton 4footer is rated for 10 gage. Ten grand, made in the USA. Seems cheap to me. I doubt you will end up with less than half that in materials by the time you are done, and, of course, probably triple that in time...

B48/040 | Iroquois IronWorker

I have seen the Iroquios ones that is a neat design using a single cylinder. I want to build one just for the experience I have no pressing need for one other than I have room and think it would be fun. I would like to bend 1/4 inch so I should probably up the tonnage a bit or make wider dies. I have seen a few press brake builds on the net and one of them is a cnc, that is over the top nice. Anyone have pics of some. I am thinking up acting and using 2inch plate. If the thing comes in around 4000lbs I will be looking at around 4 grand in it.

We just bought a small (25 ton) press brake. It's a Promecam (French) and works really great except for the fact that it's an uplift style. If you have a choice make yours so the top die moves down--makes it much easier to line your workpiece up if it's not moving. Accurpress is only a couple miles from us and they have a very good selection of die crops. They ship all over North America so I can hook you up with the right person if you're interested.

Here's a link to their site. The Load Calculator (in the upper RH corner) will help you determine what your capacities will be...

Accurpress / Accurshear - Press Brakes, Press Brake, Shear, CNC press brake, CNC shear, CNC gauging, hydraulic press brake, hydraulic shear, accurpress, accurshear, accurcrown, pressbrake, shear, brake, metal forming, fabrication

Im glad im not the only one with this idea. Iv been wanting to biuld one for a few years now but have no real day to day use for it. So Iv been try to collect parts as I see them cheap. The big thing I need is some real heavy I beam witch steel has a big price tag used. I wanted to be 8' plus 4"to6" Iv seen one biult this way on a show called Praire Farm Report. they got the tonage by usein arms kind like on the Iroquis only the were turn 90degrees and ran out the back and used 2 4"x24" cylinders one on each side. the arms were concted side to side and pivoted on a very heavy tube to keep them equal and parallel. it easly bent 8' of 1/4" no prblem.

I think tonnage will be more determined from the beam, rather than the cylinders. I would pick the beams, and work backwards from there.

The 5 inch will produce 29.45 tons with 3000psi on the tube side.

This guy built a nice one:

Homebuilt CNC press brake Mach3 - YouTube

I agree with Kpotter, that single cylinder mechanical linkage is cool. I like the mechanical advantage aspect, as well.

In looking at Youtube stuff, I wondered about using rollers for the lower die, to avoid scoring the metal. These guys are way ahead of me:
Fab Supply Rolla-V Press Brake Die - YouTube

I thought it was cool as hell: a die with rollers that are non-cylindrical.

I just ordered the cylinders 2 5x10 inch cylinders and a 22 gallon per min pump. I went to the steel yard and got a 12x1 in flat bar cut into 5ft lengths and ordered 2 18in 2 inch thick steel plates with nice curves burned out. I think I will have about 3 grand in the thing, Then I will machine a 4 way die and get the whole thing powder coated. Hope it works, makes me wish I had a horizontal boring mill to do some of the machine work.

if you watch you can pick up the old mechanical ones pretty cheap, cheap enough I would never consider building one... but thats just me. There is not a more dangferous machine in a fab shop than a brake press, be mindful every second when running one.

Sorry for the bump, super busy, seems I have just enough time to read a thread, and then its off to something else, so here's my advice Kevin: Make sure that you are aware of two things with press brakes (I say that from running a fab shop where I do mostly cnc punching and cnc press brake work myself(slash defacto foreman) day to day, and the rest of my guys do the welding/cutting/polishing etc. now), 1)you have to have a setup on the "bed" (lower slab/part, upper is your "ram") where you can tram the bed up and down on an angle. That will serve two purposes, the first will be that you can make the ram/bed perfectly parallel, which is an uber-important necessity in press brake work for a consistent bend left to right on your piece. The second reason is that under heavier loads, your frame will tend to flex, and this can cause the brake frame to twist, and give you different tram settings for different materials/thicknesses. I.e. 16ga crs will be different from 11ga 304 s/s. Reason number two for a tramming apparatus is so that you can bump-brake cones (don't laugh, you would be astonished at how useful it is). If I was you I would weld/cut/fab some sort of enclosure where you have a DTI mounted to the bed/frame interface near your tramming setup so that you can measure your bed movement as you tram it into level as you bend your test pieces. Typical fab shop with a reg run of the mill press brake might be 4-6 test bends in any given angle/material to get your angle accurate while you are tramming out any error. Here is what I think your problem will be: your motion control. Unless you are going through the effort of making some sort of crazy shim/stack stop block setup for each side (going to be a horrendous pain in the ass to do work with that kind of a rig), you will have very little control as to the final BOS (bottom of stroke) position. That position is crucial on brake work, 1)for repeatability so when you do a test bend, you know your actual bend is going to be the same as your scrap/tests (as well as all the bends in a multiple piece run), and more importantly 2) because sheet metal is way more sensitive to BOS for a bend angle than most people think. Let me give you a few examples. We work in mostly 16crs/ss-10ga crs/ss sheet metal wise. With a 5/8'' open die (our universal compromise die that we use for most runs, although we have a large selection), 16 ga has a sensitivity of .002" per degree of bend when you are close to 90deg. I.e. if your BOS is .002 lower than your previous bend, you are getting an angle 1deg more acute than the previous one, and vice versa. That doesn't sound like a lot, but 2 deg. off on a 6" flange will result in butcher work to get it in shape if you can't re-strike spot on. As the material thickness grows, the sensitivity to BOS declines accordingly. I.e. 14ga is .0035-.004 per deg, 11ga is .005-.007 per deg, 1/4" is .012-.16 per deg (that is for the punch/die combinations that we happen to use, but i'm giving it as an example). Most press brakes solve the problem by using three speed ranges in their solenoid controlled stroke. First: fast approach, where your ram is basically dropping under gravity that is just barely impeeded by hydraulic resistance. Second: your regular pressing speed (most presses will let you alter this speed as a 10-100% range). Third: finishing speed,(super slow) which is reserved for the last approx. .050" of the stroke, which lets the press have a faster response per inch with the linear actuator that is giving feedback to the controller, ensuring a more accurate bend(also adjustable 10-100% for speed). Without the fine control of the multiple stages, I don't see how you will be able to air bend accurately without stop blocks (which will be a problem tramming around if they are set on the bed vs. some sort of shelf on the frame). Either way I'm up for seeing what you do, just wanted to give you a heads-up as to a lil more in-depth look about what you are replicating. Take lots of pics as you go, and good luck.
-Andrew