Drum thickness sander for thinning leather.

[LederMaschinist]

I've been looking all over for an affordable splitter that would be useful for pieces larger than a belt blank.  I'll get lucky someday.

In the meantime, I've been thinking about whether a thickness sander could do the job.  Obviously the split would be turned to dust, but it would offer a lot more flexibility in sourcing leather if I could just buy the thickest available.

I'm referring to the type of sander that is intended for thinning lumber.  The drum is horizontally oriented and there is a feed mechanism that feeds the lumber through the sander.  Many of these machines are capable of sanding veneers and other thin cuts, so it seems they might work for leather.

I have trouble believing no one has tried this, but I have looked all over and can't find any references to the practice.   And before someone suggests it, I'm not interested in using a random orbit or belt sander to do the job.  A knife is far superior to those options.

Has anyone tried this?  Does it seem like a stupid idea?

[RockyAussie]

Forgive me if I am wrong as it has been many many years since I have used a drum sander on timber. I think that the timber is fed through with rollers at the start and finish of the drum sanding operation. The leather would just bunch up and be shredded as it feeds in I think. On the other hand I remember seeing some sort of a belt sanding operation at the Packers tannery for sanding the back of kangaroo skins that worked something along these lines. I have made up something for sanding the back of the crocodile skins that come in way to thick at times but that only does about 4" across at a time and the skin has to be moved around between the sandpaper and the adjustable pressing guide. It is basically a car wheel with a 5' belt wrapped around it and by inflating the tyre I keep the belt in place. That is built into a bench top attached to a 2 or 3 hp electric motor and a swing down arm that sets the thickness and is held down firmly with large magnets when operating. The magnets stop the bounce chattering you get with springs but with crocodile you get a large amount of variance with the scales and a flatter leather would be a lot easier. Here is a couple of pics that might help the explanation.

[LederMaschinist]

Nice.  Cool idea with the car tire.

Wood planers usually use feed rollers, but most sanders use a rubber conveyor system.  You're probably correct about the rollers, although I think it depends a bit on which way the drum spins in relation to the feed.  With wood, you'd definitely want the drum to spin against the feed direction, but with leather it might be advantageous to spin the drum with the feed to prevent bunching.

Edited July 12, 2019 by LederMaschinist

[RockyAussie]

38 minutes ago, LederMaschinist said:

but with leather it might be advantageous to spin the drum with the feed to prevent bunching.

Yes that is how I have the above set up. You still have to have a way to stop it flying through as well though.  Another one I have done that suits less wide pieces may be of interest.....

[LederMaschinist]

Your setup here was actually the precursor to my post.  I have seen an older thread or two where you showed this setup.

What you basically have here is a sanding drum (belt roller) and a table (wooden rest).  This setup is what made me think a thickness sander would probably work, assuming there are no feed issues. 

It's seems there is a large gap in the leather splitting category.  You have choices of little machines that can't really manage anything wider than a belt blank, or industrial band splitters and roller splitters costing thousands.  Drum sanders are readily available on the resale market fir under $500.  It's possible they could help fill that gap.

[SilverForgeStudio]

Following as well- I appreciate Rocky for sharing his setup (again).  Hey Leder- are you a machinist?

[LederMaschinist]

I am a machinist in my day job.  In what little time I have left over I have started to dabble in leathercrafting.  I've been putting together a little studio in my basement over the last 8 months or so.  One of the abilities I'm lacking at the moment is the ability to split or thin leather in any way that's useful.

I have actually designed and built several metalworking machines for my business, and the gears are now spinning again.  I've been tossing around some designs for setups that would allow a home based leatherworker to split or thin leather at home in a useful and affordable way.  True splitting might be out of the realm of possibility, so that's why I also say thinning.

Edited July 14, 2019 by LederMaschinist

[RockyAussie]

On 7/13/2019 at 6:05 AM, LederMaschinist said:

Your setup here was actually the precursor to my post.  I have seen an older thread or two where you showed this setup.

What you basically have here is a sanding drum (belt roller) and a table (wooden rest).  This setup is what made me think a thickness sander would probably work, assuming there are no feed issues. 

It's seems there is a large gap in the leather splitting category.  You have choices of little machines that can't really manage anything wider than a belt blank, or industrial band splitters and roller splitters costing thousands.  Drum sanders are readily available on the resale market fir under $500.  It's possible they could help fill that gap.

It would be interesting to find out more on the drum sander idea. They are rare as rocking horse poo here in Australia and I doubt there would be any for that lower price unless they are fit for parts only. In my experience keeping the leather under some sort of control whilst undergoing the sanding has been very challenging compared to timber. Another factor is trying to keep the job down to a one man operator, meaning not wanting to have a feed out person as well. Another machine I made many years back I still use today uses a rubber V belt to transport the belts as I sand the edges and the belt needs to be rough sandpapered on the run every hour or so of use. If this is not done the belts will shoot through and not get sanded properly on the edges.  This one I can use by myself as I am able to reach over and take the belt as I feed another one in. Note at the back there is a rubber roller that sits between the sanding drums and keeps pressure down in order to restrain the belt down onto the V belt. It has a spring that is adjusted down to suit the pressure of the work. This is very little sanding pressure compared to trying to do a whole larger piece of leather.

This flasher one below I have been working on does 3 different sanding jobs at the same time but has the disadvantage of being to long for a single operator. It worked well on dress belts edge sanding but the motors were insufficient in the lower rev range for my hornback belt sanding. Further motor testing is now being done. This model I designed so that by turning a wheel on the side I could get the table tops to adjust to the wider and thinner belts with just a simple turn. It will probably be all redesigned to be shorter again to suit a single operator.

I will try and load a video or 2 over the next week showing how they operate.

[LederMaschinist]

I like your style RockyAussie.  If you can't get it, just make it.  Although it appears you have a bit of a rust issue going on there.  Call it coastal patina.

I was going to provide links to drum sanders from craigslist in Australia, but sure enough, I couldn't find a single one for sale. 

Here's the type of sander I'm talking about if anyone isn't sure what I'm referring to:
 

https://www.grizzly.com/products/Grizzly-12-1-1-2-HP-Baby-Drum-Sander/G0459

Edited July 15, 2019 by LederMaschinist

[SilverForgeStudio]

@LederMaschinist Not a prob- if you want to explore a  "Novel" way to thin with a knife look into the industrial planer blades- M4 or D2  and up to 18 inches long- Although at 1.25-1.5 inches wide as well.  If you use any HSS you are ahead of the curve for edge retention with a decent hardness (using a chisel grind).

Use some mild steel with a couple of press fit bearings, angle iron struts for bracing and stabilization and roller assembly for pinch/guide and a 16tpi thread to the blade height adjust (divisor of 64 for "easy" thickness calculations).

Ive been trying to cobble one up around home but "life" keeps getting in the way- I like Rockys' sander assembly but dont have the room in my little garage for the setup... Im still just experimenting and tinkering... You may have a bit (HA! A Ton is more like it!) more ability with the machining shop versus my hacker-space tinker bench!

Just a thought- Be safe and as always- have fun!

[LederMaschinist]

I've though about building a hand cranked machine from scratch.  I actually do a lot of grinding and cutter work in my day job, and in my opinion the blade would actually be the easy part.  I thought about modifying a purchased rolling mill used for jewelry making and such.  It basically already has everything but the splitting blade already there.  The bottom roller would have to be textured for grip, and perhaps mounted on springs to apply even pressure on leather that's uneven in initial thickness.

The other route I have considered is basically a guided "plane" where the blade follows closely behind a roller that would apply pressure to the leather to hold it in place and and ensure it's pressed flat against the work surface.  The plane would ride on a rail suspended over the work surface and would shave a strip about 1" wide.  The working idea would be you lay the piece of leather on the work surface, grain side down, and pull or push the plane across the leather.  Then you'd advance the leather over slightly less than the width of the cutter, and take another pass.  You'd basically thin the leather in 1" wide passes more or less "mowing" it thinner.  Even a large piece would go quickly.  And size would only be limited by the length of the rail that the plane rides on.  I'd use inexpensive linear rail with a bearing block to guide the plane.