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Dr. Rob
05-08-2003, 12:49 PM
Has anyone besides myself considered making um, what the heck...(all of a sudden I lost my vocabulary...what-do-you-callums..)

(Rollers, or a rolling machine rather, for the progressive bending of round or square tube or stock, channel or angle bar, generally into constant radii or circles. Sheet metal rollers, but for bar stock.)

I get this idea every now and then, and don't think it should be so hard. The machines from companies like Roundo cost plenty; I don't know why.

Generally they're built up of two beefy slabs of sheet metal seperated by a distance of ten inches or so and mounted to a common base.

Three wheels are arranged in a common plane, in an approximately equilateral triangle. Beefy axles run through the wheels and both side plates. One of these axles is provided with a motor drive through a worm. Another of the axles is adjustable in center-distance relationship to the others, by way of a beefy screw for instance.
Beefy wheels are provided for various sizes or profiles of stock.

Now, how hard could that be? Anybody tried it?

SID
05-08-2003, 01:26 PM
DR- I made someting like that once. I put two bearing on a plate about 4.00 apart on the same x axis. bearings were approx. 1.50 dia. then I had a third solid roller that I mounted in the mill head. The plate was mounted in the mill vice, the head centered between the two roller bearings. That way, by controlling the y movement, I could control the finished radius. I was forming .125 x .375 flat material. worked well for this light aplication.
-Sid

Dr. Rob
05-08-2003, 03:17 PM
Sid, man...great minds (simple minds?) must think alike. Was well on my way to doing just that, since my mill has a big ol' table and 360* rotating head in both planes, gearbox and friction clutch...perfect. But, was advised not to subject the spindle to such abuse. Hmm, maybe I'll do both. Start with the mill trick and then move on to a real machine. Anybody else try this?

ibewgypsie
05-08-2003, 03:22 PM
Look up Model 3 bender. It will bend solid bar. The dies are kinda pricy, but you could make your own. I have one I bend .25 wall dom motorcycle frames with. I got two dies, protractor plate, ratchet handle and bender for 800 with shipping. The dies were almost half the cost if I remember.. It is the major type of bender used by race car manufacturers for roll cage bending.
HF (choke) has a small metal bender that was on sale for 50$ on the other end of the price scale.
I plan on making some laminate dies for my my model 3. I saw one site they used plywood dies bolted together to bend exhaust tubing.
For the strength and design engineering you can not beat a proven and tried product.
For mounting mine, I used the seldom used english wheel frame. I put 2 inch recievers top and bottom, just welded the mount to a 2 square stock and dropped it in. Bender pics at
http://www.vansantent.com/model_3_bender.htm
I wanna hydraulic cylinder and electric pump for mine. It is a lot of sweating to bend .25 wall.

we used to roll sheet at one place I worked.. we added 3 solid 4 inch rollers with one top under a press, both sides were independent so you could roll cones. TWO people lost fingers before I added a inverter drive to the drive roll to make it speed control.. one set of men steering in, one set steering out, one man on speed control. We built stainless dye tanks there.

Stepside
05-08-2003, 03:27 PM
I built one that will put an arc in 2 in. by 2 in. by .187 wall square tube. It is manually powered. I have done as sharp a radius as .18 inches in 1.25 square tube with a .125 wall. At this time the tube was severly distorted. On the larger radius it works fine.
It is three rollers between 2 side plates. The middle or top roller is the "powered" roller and is also adjustable as to distance.
Right now I am grooving the power roller so I can do angle. This will allow me to do angle with the leg on the inside of the arc.
.500 steel side plates. .750 bolts for axles. 1.00 bolt for adjuster.

Dave Opincarne
05-08-2003, 07:02 PM
DITTO!! I've also been thinking about something like this. Kind of like an english wheel for tubing. Three wheel, control the bend by moving the single inside wheel closer to outside two. By adding bend in small incriments and moving the workpiece back and forth from tangent to tangent. Is this what others are describing?

-Dave

wierdscience
05-09-2003, 12:07 AM
I have been building one for about three years now!I never get finished because its one of those projects that as soon as I start something comes up to stop me.I am making mine out of5/8"plate for the sides and 2-1/2"shafts for the bottom two rollers both of which are driven,the third roller is dead and is mounted on a large caged needle bearing,I plan to use steel plate burnt out to make the dies,I used one of the roundo machines once to make some spiral staircase rails,we took 1.5"square tubing and twisted it in the lathe with a 3/4 turn,then we fed it into the roller and by bending a little each pass we formed a perfect segment of a helix,the rest of the guys in the shop as well as the boss were all empressed.

Dr. Rob
05-09-2003, 02:51 PM
Yes Wierd, something like that. I think needle bearings are almost a must because of the tremendous axial load. Well...better, anyway.

Dig the trick on the spiral staircase thing. Twisting the tube BEFORE rolling...fiendishly clever. Those railings are something I've done too, and it can leave anyone scratching their heads as to how to go about it.

Yeah, on the dual drive. It may be neccessary, since just one wheel might not provide enough friction to push the job through. I was thinking to get away with a couple of sprockets and roller chain. Don't know about the diameter of the wheels yet, but those axles gotta be BEEFY.

Had this idea once for a smaller version, utilizing two telescoping square or rectangular tubes, like 5" or 6". The outside tube has the two wheels and axles on it; the inside tube has the third. The inner tube slides in the outer, and provides stable framework and steering for things like a hydraulic jack or screw. Drive could be from any of the three. Hmmm...

ibewgypsie
05-09-2003, 04:58 PM
On the sheet roller, we kept busting bearing pillow blocks. I used brass bushings with steel pipe outers, greased and fitted. The bottom two rollers were driven, kinda hard to start if I remember, we'd have to raise the top put end in.. and run back and forth while lowering top roller. usually was some loss on both ends too.
If you get something to working please post pictures.

wierdscience
05-09-2003, 11:39 PM
I used a needle bearing with a 3"od 2"wide and an id of2-1/4"with an inner race,the catalog says they are good for 15,000#'sat 400rpm,we will see,for the slide I have a piece of 1"plate about 10x12"held on with some gibbs made from 1x2" flatbar bolted on with many bolts,similar construction to a square way on a mill.I was going to use 8" od rollers closer together,but then I talked to an old hand at a local shop that does this sort of thing and he told me bigger wheels spaced further out are better,he sugjested 12"od set about14"apart,says it will provide for more traction and less effort to bend what ever cross section I will be using.This guy works in a shop that does nothing but round work,they got a big set of rollers that will handle8x8x5/8"tubing,and a bigger one that will bend a 18"wide flange beam the hard way!This is a sight to see in the process the flange on the outside gets thinner,it went from .500"to about.375"before they were through,they also got a cnc plate bending roll with 4 automated power rollers that will do some really neat stuff like making an eliptical tube out of 3/4"plate!I didn't stay to long,big plate rolls are a sexual atraction for me, http://bbs.homeshopmachinist.net//biggrin.gifalong with mills,lathes,planers,boring mills,etc. http://bbs.homeshopmachinist.net//biggrin.gif

barts
05-10-2003, 12:22 AM
I made a roller for 1/2" EMT; I used it to
form the gentle bends I needed for the canopy
on our 19' steam launch. The two idler wheels havecam follower bearings (needle), the main
roller which is hand-driven uses two ball
bearings. It's way over-built and a buddy
used it to make duck blind forms out of 3/8"
pipe... All the rollers are attached to some
8" angle...


- Bart

Dr. Rob
10-07-2003, 02:49 AM
I just went and got this thread out of the filing cabinet, since Knucklehead started that other one on the same topic. Might as well let them run concurrently, so's we can see what we decided last time around.