Homemade tubing roll pressure carriage guides

I’ve read through I bunch of these homemade tubing roller threads, and I know it’s been beat to death, but I’m wanting to do something different than I’ve ever read , and need advice on what I need.

The tubing roller I’m building is going to be an open design so it’s not caged and an actual ring can be rolled without having to disassemble the unit to remove tube.

The bearing carriage, or I’ve heard it called the slide, that moves up and down to create the pressure to bend the tubing, I’m wanting to have linear bearing guides instead of slide plates to keep it the load equal on both side or at least keep all sides of carriage moving in unison.

I’m not sure if I need square or round linear bearing, or if square do they need to be a closed bearing that would wrap around the entire guide bar or an open where one side is,well,open? It’s going to be a high load I would think so if I could get some info I would appreciate it. Picture below is the design I’m building.

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You are focusing on solving something that is not a problem. There is no need for perfection in this movement- in terms of left to right movement, you just need a single contact point, it doesnt matter if its perfectly centered between the two lower rolls or not. Made properly, a simple greased sliding fit works really well.
If you have extra money or time, there are several other areas that you will see much more bang for your buck- ie-

-make a double front plate, of thicker material. 1 1/2" thick plates is a good start. 2" would be better.

-increase shaft and bearing size. a minimum of 1 1/2" diameter shafts, but, again, 2" would be better. Make of out of something decent- 4340 or some similar tough but hard material.

-make sure you have a hefty sprocket/chain drive connecting the two lower driven rolls- or, better yet, upgrade to hydraulic motors- 3, if possible. Driving all 3 rolls makes a machine much better- its what Roundo does. BPR uses gear drive on a very high torque, low rpm gear motor- thats the second best solution after individual hydraulic motors.

-add hydraulic up/down to the center top roll- again, you will find it much easier to use and much more capable if you do.

all of these things will increase accuracy, repeatability, ease of use, and capacity.
your linear bearings will do nothing in any of these categories.

Here is the parts diagram for my slightly larger BPR rolls (Eagle in the USA) I bought em new almost 20 years ago, and have subjected them to way above and beyond the call of duty- and never a problem with the sliding function. What wears is the keys holding the dies on the shafts, the retention pin on the top slide, and the dies themselves. Those are the stress areas. Overbuild the drive train, and the rest takes care of itself.

Copy this design as much as you can- it will be worth it. These guys make hundreds of machines a year, they know what fails and have corrected it over time.
Here is a photo of my machine rolling 1 1/2" diameter solid stainless round bar into a tight (24" diameter) circle. All that engineering makes this very difficult rolling possible.

Hell yeah,thank you so much.the motor and drive I have is a 1/8hp Balfour right angle with a gear box, off of a set of tank roll positioner. It has some heavy sprockets mounted to the shafts that turn the wheels and that’s why I thought about using that. I would like to gear the whole thing like the plate rolls I work on at work but that would be to costly for me as I am just starting out,trying to build up some things before I go out on my own. On the shaft I actually already ordered 1-1/4” bearings and I went with that size bc the only dies I could find info on,which were very very few, I only saw 3/4” bore,so I figured 1-1/4 bearing bushes down would be fine. Do you have any info/specs or a website that lists there dues dimensuons?

Okay so no guides just slide plates,gotcha. As for as hydraulic cylinder for the bending roll I was looking at a screw actuators as I am not wanting to have to buy a hydraulic pump and all of that.the plate rolls I use are very old and instead of hydraulics it uses two I think it’s a worm gear to lift the rear roll so do you think something like that would work? I agree that hydraulic it’s the best way and maybe one day I will.

That’s a badass roller you have and I will take your advice copy it as close as I possibly can. Again I appreciate it.

1/8 hp is kinda like when VW bugs had 29hp engines.
My rolls, which are rated for 2" schedule 40, have a motor that is 3.5 hp 3 phase. Roll speed is about 10rpm.
For raising and lowering the center, upper roll, an acme screw is good- you want a big one, though, as all your downpressure is achieved there. Maybe 1 1/4" or 1 1/2" Acme, with a crank on top. Its part no.71 on the drawing.
The shafts for the rolls are turned down, on mine, to about 1" od where they go thru the roll. But are bigger where they go thru the bearings. And they are keyed- a keyway is cut in both the id of the roll and the od of the shaft, and a square key is used. Easier to make that way, but you cant have the two driven, lower rolls, slip on the shafts. Upper center roll can just be unkeyed, and held on by a big nut. It can spin, it actually may help things. But the bottom ones need to run together and not slip, which is why most cheap rolls have sprockets and drive chain on them to the motor, so they both spin at the same speed and in tandem at all times.
If you use lighter weight materials, you will find out where the stress points are, and what breaks. Its a learning experience.

big sturdy tools cost money. Even if you build em yourself. But you will learn a lot, and improve it with time.

If you change to a enclosed design you need nothing like the materials, i have done 15x60mm flat steel the easy way on mine with nothing but needle roller bearings and 25mm chromed hardened pins. I can't do 1 3/8" square though, just would not go, but that possibly was not mild steel but something harder.

The biggest I was planning on rollin is 2” thin wall tubing. The problem is getting material that thick and then having to move it around as I will be building it in my garage by myself. The place I work builds pressure vessels and I have been there a long time building these things and have never seen a piece of 1-1/2” thick plate. The closest to that would be a 20” flange and that thing way heavy. I was thinking of building out of .75 or 1” 6061 or even 7075 aluminum but you’ve got me thinking now that’s a bad idea? The original plan was to do a caged design until I realized I would have to take it apart to remove a ring but that design for sure has its place._

And since I done have a a mill to do any precision holes to mount bearings, I’m going to have to use 4 bolt pillow blocks. Do y’all have any recommendations on a type as all are not created equal?

Also if it was just the motor powering it I would not use it but the gear reduction case make a huge difference. We have rolled some big heavy tanks with this setup and never had a problem but that’s what they were built far. Also like hydraulics where they stop immediately when you let off I can do the same by setting the brake in the controller. It’s a baldor 90v dc motor. But I wouldn’t even think about using it if it didn’t have the gear box.

I'm not sure of the status of this thread but here are some pix of a triple roll I built years ago to roll brass rings for banjos. I have rolled everything under the sun with it and it hasn't exploded yet.

Stuart

atomarc said:

I'm not sure of the status of this thread but here are some pix of a triple roll I built years ago to roll brass rings for banjos. I have rolled everything under the sun with it and it hasn't exploded yet.

Stuart

View attachment 253586 View attachment 253587 View attachment 253588

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you should look at atomarc's design-
looks like his plate is only 3/4" or so, but his shafts are nice an big, and decent sized bearings at both ends.

thats at least a one horse motor, gear drive to lower rpm, then a chain driven gear set that drives the two lower rolls.
hand crank height adjustment on top center roll.

tank rolls need torque, but dont hit any resistance. I am guessing the 1/8 hp motor is going to stall out way before 2" tubing.
There is a lot of resistance in the downward pressure needed to get a radius. Of course, you can roll a tiny increment of radius at a time, and crank it tighter, but that gets old fast.
Find a bigger motor. For 2", I would want a minimum of a horse and a half, and that is for thin wall 2".

Just for accuracy's sake, all the rolls are powered. Motor is 1/2hp and gear reducer is..if I recall, 50:1.

I found it very misleading on exactly how much 'oink' it takes to bend/roll steel. Brass, not so bad.

Stuart

I had no idea that anyone had commented on this and just noticed so thank y’all. I’ve got my front and back plates shape cut out but still needing to find someone to water jet the slide slots in those plates. I took your advice Rise and everyone’s for that matter But ima go with the T slot design similar to yours “Rise”. I bought a lathe and mill that is on their way after I was quoted 600 just for the carriage and that’s if they don’t have to buy a piece of metal. 600 was to just face and true a block of steel and shoulder notch it. I’ll do it myself now. Thank yall