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Black Forest
10-28-2017, 11:20 AM
I want to build a powered leather splitter. There are two rollers the the leather feeds between to force it onto the cutting knife. The bottom rooler is knurled and slring loaded to push it against the flesh side off the leather. The thickness of the split is determined by the distance between the top roller and the blade. Tah is usually adjusted with a knob on top of the machine.

Now my question. How would you design the gearing so the distance between the rollers can vary but still be gear driven? At tbe moment I am designing it with four gears on one side.

Illinoyance
10-28-2017, 11:32 AM
George H Thompson published plans, I believe in Model Engineer for an initial pinch roll for bending metal sheet. He used a 4 gear arrangement to drive the top roll. Try a Google search.

reggie_obe
10-28-2017, 11:37 AM
I'd copy the design of one of the Landis machines.
http://www.pilgrimshoemachine.com/stitching_machines_d.html
Might even find a suitable candidate of German Ebay.

CCWKen
10-28-2017, 11:42 AM
I wouldn't think you'd need too much movement for material thickness. The gears on my 3-in1 sheet metal roller are just stacked so the thickness is limited to tooth engagement. You could extend this movement by allowing the movable gears to arc or move on a tangent to the drive gear(s). I could draw an example but loading pictures is such a PITA.

Black Forest
10-28-2017, 12:04 PM
I only need about 7 mm travel.

CCWKen
10-28-2017, 12:16 PM
That would be a piece of cake. You wouldn't even have to swing on an arc. Just make the driven gears move on a parallel vertical line. Adjust the spacing on the gears so full engagement is on a center line. 3.5mm up and 3.5mm down would still give more than enough tooth engagement unless you're pumping 300hp. through the gears. :)

Alan Smith
10-28-2017, 02:11 PM
One of my clients, a bearings and belts suppliers, has a couple of skiving machines in at the moment to measure up for replacement belts. There seemed to be a lot of belts and not many, if any gears. I'm back there next week, I'll have another look.

boslab
10-28-2017, 03:25 PM
On a rolling mill the rollers are coupled to the gearbox with driveshafts, the bottom roll is fixed so straight through will do, the top must be able to raise and lower, so it's coupled with a driveshaft with two universal joints in, on a mill they call them wobble boxes, perhaps you could do the same?
Mark

Norman Bain
10-28-2017, 04:02 PM
As the OP suggests, a 4 gear approach does work to create a mechanism that allows adjustment while at same time maintaining full contact of the gearset.

http://downloads.purposebuilt.com.au/NJB/SheetMetalRoller/EndView.jpg

Black Forest
10-28-2017, 04:28 PM
One of my clients, a bearings and belts suppliers, has a couple of skiving machines in at the moment to measure up for replacement belts. There seemed to be a lot of belts and not many, if any gears. I'm back there next week, I'll have another look.

Those are probably using a bandknife. Just like a bandsaw blade but no teeth and sharpened. That is how belts would come into play.

Black Forest
10-28-2017, 04:32 PM
This is what I want to build or something similar.
https://www.youtube.com/watch?v=9bPmLCu3Otk

rohart
10-28-2017, 08:19 PM
When I motorised my bead roller, I used bicycle chain. I took a couple of bike cassettes apart to get the gears. You can run chain with enough slack to allow quite a lot of adjustment and movement, and it's so cheap you can experiment with gearing as much as you like. You just need to make up a few adaptors for your shafts.

A little hiccup as you start, till the chains are tight, is unlikely to mess with the feed.

So I take it you'll be adapting the shearer for skinning cattle ? Or are we really talking sheepskins here ?

wtrueman
10-29-2017, 02:39 AM
That would be a piece of cake. You wouldn't even have to swing on an arc. Just make the driven gears move on a parallel vertical line. Adjust the spacing on the gears so full engagement is on a center line. 3.5mm up and 3.5mm down would still give more than enough tooth engagement unless you're pumping 300hp. through the gears. :)

I bought a probably nearly unused scroll saw, got a largess blade and sharpened it. It works well. My two cents.

Black Forest
10-29-2017, 05:01 AM
I bought a probably nearly unused scroll saw, got a largess blade and sharpened it. It works well. My two cents.

Are you using it on leather?

Black Forest
10-29-2017, 04:51 PM
This is a side view of a popular splitter. I get a feeling that it could be better engineered with todays possibilities. What do you think?

https://www.use.com/images/s_2/469b02b30537c8b5942f.jpg (https://www.use.com/NbpIg)https://www.use.com/images/clicklarge3.gif (https://www.use.com/NbpIg)

boslab
10-29-2017, 04:55 PM
An old fashioned mangle with a planer blade?
Mark

reggie_obe
10-29-2017, 05:18 PM
This is a side view of a popular splitter. I get a feeling that it could be better engineered with today's possibilities. What do you think?


I think the companies that made for the leather industry, be that shoes, boots or trim, designed and built them as well as they needed to be.
For instance, why do you think it needs to be motorized to be better?

MrFluffy
10-29-2017, 07:06 PM
Looks complicated, and four gear drivetrain also.
It strikes me that this is rather similar to the issue with a bead roller for driving the top roll. There they get away with just imperfect geometry as the gears move out of mesh for the limited movement.
https://s-media-cache-ak0.pinimg.com/originals/f3/bf/47/f3bf474a40408a64fd2d1cf35c8d70d4.jpg

Black Forest
10-31-2017, 08:31 AM
I had a little time before lunch so I modeled what I would like to build. The rolls will be just over 300mm wide(12 inches). The difference in what I want to build and what I have seen in person and on the internet is the way that I will deal with leather thickness and clamping pressure between the rollers. This will be a slide within a slide arrangement. The red slide is controlled by the top knob. The red slide determines the thickness of the split as in how far the top roller is above the cutting blade. Leather is split with the hair side up and the flesh side down against the knurled roller. The blue slide will be for adjusting the clamping pressure. Doing it this way will allow me to change how thick of a split I make from piece to piece without having to adjust the clamping pressure for each piece. This will save time and be more efficient. The wider the split the more clamping pressure is required to make the split.
I bought an old shoe makers skiving machine off Ebay for 29 Euros. I bought it just to get the two gears on the side that are mounted on the roller shafts. The gears have long teeth on them to allow for more or less spacing between the rollers. The unit I bought was not complete and not usable as bought. I did make enough of the missing parts to get it to work for splitting straps not wider than 35 mm.

https://www.use.com/images/s_2/5a18c6f025ecceb4e4cf.jpg (https://www.use.com/NckxO)https://www.use.com/images/clicklarge3.gif (https://www.use.com/NckxO)

wierdscience
10-31-2017, 08:55 AM
Why not use just two gears on a fixed center distance off to the side of the machine and send power to the shafts via a couple universal joint driveshafts?

Black Forest
10-31-2017, 09:56 AM
Why not use just two gears on a fixed center distance off to the side of the machine and send power to the shafts via a couple universal joint driveshafts?

That is certainly one way to do it. But the amount of adjustment needed is minimal. As in 7mm max. The long tooth gears accomplish this without any problem.

RichR
10-31-2017, 10:07 AM
The long tooth gears accomplish this without any problem.

Until they start to wear, or become "long in the tooth" so to speak.:rolleyes:

Black Forest
10-31-2017, 08:13 PM
Until they start to wear, or become "long in the tooth" so to speak.:rolleyes:

This splitter won't see much duty and I mean hardly any at all so I am not worrying about wear. It might break but it sure won't wear out with how much I will use it.

lugnut
10-31-2017, 08:50 PM
When I think about a drive for a adjustable feed/and splitter I think how the swing arm on a motor bike works. it could use either chain or gears along a arm.

Black Forest
11-01-2017, 06:36 AM
Here is the machine I bought for the gears. You can see in the picture the long teeth to allow for movement of the two rollers.

https://www.use.com/images/s_2/b548122f411804985ebe.jpg (https://www.use.com/NdFws)https://www.use.com/images/clicklarge3.gif (https://www.use.com/NdFws)