DIY slip roller, tubes or solid?

[EddyCurr]

One afternoon an engineering student was riding across
campus on a shiny new bike. He ran into a friend of his,
also an engineering student, who said, "Wow, that sure
is a nice bike. Where did you get it?"

"Well, the darnedest thing happened," said the first engineering
student. "A girl came riding up to me, got off the bike, threw
off all of her clothes and said I could have anything that I wanted."

"Wow, that's great," remarked his friend. "Good choice, her clothes
probably wouldn't have fit you anyway."

.

[Norman Bain]

I am trying to figure out gears. When matching gears what things need to match for the gears to mesh right? I was looking at some gears that all listed a 16DP but then mentioned 1/8" pitch and .870" pitch, and whatnot. Then there is metric gears, I am lost.

What I am looking for is two 2.5"OD gears to be mounted on two rollers. Then a 6"OD(ish) idler gear as well as a 1.5"OD(ish) idler gear. All 4 need to mesh with each other. Cheap is best so I have been looking on ebay for used or left overs. Seem to be plenty on there and many of the sizes I need but the tooth pitch and stuff confuse me. I had my shopping cart full of a set of gears I thought were all matching (all 16dp gears) but then before I was going to check out I noticed the 2.5"od gears had 62 teeth, and the one 5.75" gear had 66 teeth. That doesn't add up to a very good gear reduction and doesn't make sense for the teeth meshing well even though they are both 16dp.

Bore makes no difference as I can make it bigger or turn down the shafts to whatever I need.

Help!

Try this for a design. There are 4 gears required to make the pinch rollers turn in the correct (same) direction wrt the stock being fed thru them.

In this design (which is still a work in progress) the top roller is attached to an arm that rotates about the axis of the top ider. This allows the top and bottom pinch rollers to be at any distance between each other (to accommodate thicker or thinner stock) while at same time keeping the gears in perfect mesh.



My feeling is that the bottom pinch roller is the one that has the crank. The bottom pinch roller is cranked anti-clockwise in this view. The gear on bottom pinch roller drives the wide idler; which in turn drives the narrow idler; which in turn drives the upper pinch roller in correct direction.

The upper and lower pinch rollers in the model are 50mm diameter.



My apologies for such a scruffy model. It was something I was tinkering with back in May 15. I see I have started adding in the bearings and it is all a bit broken. Also see that this version has a radius roller design (not fully shown) that aims to be small in diameter so as to get as close to the main (pinch) rollers as possible. The radius roller was aimed to be supported along its length and was also on arms that caused it to move in the arc of the lower pinch roller.

The gears are all modeled; can be imperial or metric; can be resized by changing the number of teeth and (for metric) the module number. The model then provides the pitch circle radius for each gear. The bearing centers for each pair of gears (shafts) are then modeled to be the addition of the pitch circle radius for the pair.

This image is of a portion of the equations. Changes are made to the values starting with "CONTROL_" and the model updates to match.


I would provide a run of the model if you provide some metric gear tooth counts and module size.

Cheers,
Norman

[metalbender]

The plans I found in the Metalweb sites use sprockets instead of gears. Upper and lower are driven, the rear one free wheeling. Mine has 2" solid rollers 25" long. It takes quite a bit of grunt to roll a 3" cylinder for stove pipe from 16 ga material 10 inches in length. A longer crank handle would help, just haven't got to that. Every time I use it I'm reminded though, as in yesterday.

[Boostinjdm]

I was just planning on chain driving the two lower rollers. The rear one will pivot around the front ones axis to provide the pinch. The top roller would be free wheeling and mounted with some quick release method. Or maybe just some big bolts and keep a wrench handy. I really have no need to roll full cylinders.

An electric gearmotor with a high reduction would be a nice way to power the rollers.

What were you planning for power VPT?

[vpt]

I am going the pinch route where the two pinching rollers will be the powered ones. The "bending roller" will be the free roller.'


I want the gears to incorporate gear reduction spots for the hand crank handle. Looking for something like 1:1 off one of the rollers, a 2:1 off one of the idler gears, and then a possible 5:1ish stand alone idler gear. I plan on all arm power right now but am leaving the build open on the drivetrain side for a possible motor addition later on.

Yes I like to shoot from the hip. I never was much of a plan guy. I do plan ahead a few steps when building something but I am not the type that needs a completely planned out CAD drawing in front of me in order to get anything done. Its all in my head.

[vpt]

Here is a funny one...

As I was watching one of the rollers go round and round in the lathe this morning I was thinking to myself about these nice smooth surfaces I am trying to get on the rollers. I was thinking what kinds of stuff might ruin the nice surface and I started thinking of the slag from the plasma cutter on parts I will be rolling. Then it struck me, is a "pinch" roller the best for rolling stuff like plasma cut fire rings with slag and stuff on the cutouts? Maybe a pyramid type roller would be better suited for what I want to do?

What are the benefits of a pinch roller over a pyramid roller?

[J.Ramsey]

I am going the pinch route where the two pinching rollers will be the powered ones. The "bending roller" will be the free roller.'
I want the gears to incorporate gear reduction spots for the hand crank handle.

That's pretty much how my Grizzly 16 gauge x 50" roll is set up.

The gear on the crank handle shaft has 13 teeth, the gear it drives is a 41 tooth that drives the top roller,behind the 41 gear also keyed to the roller shaft is a 14 tooth gear that drives the 20 tooth idler gear located to the right which drives below it another 20 tooth gear that idles on the shaft behind the 13 tooth crank gear which then drives the 14 tooth gear on the lower roller.
The lower roller has about 1/2" vertical adjustment,the rear "forming" roller 3-1/2"
It takes a hair over 3 turns of the crank handle for one roller revolution.

[metalmagpie]

No comment on the relative merits of pinch vs. pyramid. But if you clean the slag off the torch-cut edges (plasma slag knocks off a lot easier than oxyfuel slag, sticky bits: use a sharp chisel) it won't hurt your rollers.

You know, if you cut correctly with a plasma cutter there isn't a whole lot of slag and you can tap the piece with a screwdriver and what there is falls right off.

metalmagpie

[vpt]

Thanks very much Ramsey for the pics! That is exactly what I had planned!

No comment on the relative merits of pinch vs. pyramid. But if you clean the slag off the torch-cut edges (plasma slag knocks off a lot easier than oxyfuel slag, sticky bits: use a sharp chisel) it won't hurt your rollers.

You know, if you cut correctly with a plasma cutter there isn't a whole lot of slag and you can tap the piece with a screwdriver and what there is falls right off.

metalmagpie

Yes pretty much everything I ever cut you can knock off the slag with a screw driver but every now and then an edge or corner will get a pimple of metal or hard slag that doesn't come off. I just wonder if it will be enough to cause me trouble almost every time I try to roll something or not so often?

[J.Ramsey]

I use a flap wheel on a 5" grinder on any offending edges because if not ....in time the burrs will show up as dings on roller.

Same goes for any material that goes thru either of my brakes.

I won't even consider any plasma or flame cut material to get re cut on my foot squaring shear.

[Norman Bain]

I found myself needing to do a refresher on Pinch vs Pyramid styles. Found a good link below.

http://metal.brightcookie.com/7_form/form_t1/htm/form1_2_1.htm

An a short list of the advantages and disadvantages of each is here.

http://metal.brightcookie.com/7_form/form_t1/htm/form1_2_1apop.htm

The pinch style to me seems more versatile for the home shop. The pinch rollers truly "grip" the stock and feed it onto the radius roller.

Pinch style should result in less slippage; therefore less potential skew. The pinch style also allows forming closer to the butt ends of the stock being rolled.

Cheers,
Norman

[vpt]

http://metal.brightcookie.com/7_form/form_t1/htm/form1_2_1.htm

Cheers,
Norman

Thanks for posting that!

An interesting tidbit at the bottom of that page. Double initial pinch roll! With the center roll stationary and the bottom two rollers move toward or away from the center roller (I assume at a downward angle away from the center roller). Looks to me this design could be used as both a pinch roller and pyramid?

[vpt]

How come no one ever mentioned getting and involute cutter (one to make all matching gear teeth no matter the diameter yes?) and make my own gears?

Some friends you are.

[RussZHC]

'Cuz fairly common DP in many sizes are relatively cheap, http://www.ebay.com/itm/CLAUSING-100...8AAOSw4HVWDE~U unless you want the making exercise which is not a bad thing...that listing happens to have two pinned together but a fairly wide ratio between them

[vpt]

Missed out on a very nice Carrol 10" dividing head on ebay for $270 shipped...

After the finding of the double pinch roll, if I go that route the gearing idea might all be out of the question. I have to ponder over the idea for awhile. If I go with the double pinch roll a chain system might be used. Our local Fleet Farm happens to have a complete selection of chains and sprockets too.