Splicing sandpaper

Tano · Post by **Tano** » Wed Apr 08, 2009 8:57 pm

Hi Guys,
I would like to build myself a belt sander to shape the briar. Just purchaced the roll of sand paper. The question is how do you splice the ends together? Some have suggested to tape the ends with duct tape, or strip some grit to expose the cloth then apply contact cement, or epoxy the ends. Those that made these suggestions admitted that all have failled.
Now I turn to the experts for help. What say you?

Frank · Post by **Frank** » Wed Apr 08, 2009 9:28 pm

I took a quick look at my manufactured belts and one thing they all have in common is that they're spliced at an angle, not straight across the belt.

The heavier weight belts are spliced using a lap joint, i.e. about 1/2" grit removed, the edges tapered (like a flat ground knife edge), and then glued.

On the lighter weight belts, the ends are butted together and a narrow, thin strip of flexible, but strong, plastic or nylon is glued over the butt joint on the back of the "sandpaper".

I can't think of a glue to recommend, but I think Epoxy cures too brittle to make a lasting joint.

It is also preferable to use cloth backed abrasive rather than paper. Make sure it's good quality - it'll piss you off no end using cheap generic "sandpaper" when it wears out after a few short uses.

I know I was.

Post by **KurtHuhn** » Wed Apr 08, 2009 9:37 pm

Given the time involved in making grinding belts, and the questionable quality of such that you'll get from using sandpaper strips to make belts, I'd suggest sticking with the standard sizes from established sources. At worst, your homemade belts will piss you off, at worst they'll take out an eye when they self destruct as you turn on the grinder.

If you're building a grinder, stick with 2x72 belts, as those are most popular and most readily available in grits from 24 (and less!) right on up to 600+. Since you're building it yourself, you've got all the freedom to build it your way anyway - might as well build it to use consumables that can be bought at any decent machine shop.

Tano · Post by **Tano** » Wed Apr 08, 2009 9:58 pm

Kurt,
The 2x72 belt you are suggesting are these the flexible J weight? Where in the USA can a person get them? I have not found any in my Province. The only ones I see are the stiff belts.
The origin of my escapade comes from a picture of Rainer's sander.
http://pipedia.org/index.php?title=Belt_Sander

Frank · Post by **Frank** » Wed Apr 08, 2009 10:09 pm

I've used these guys for many, many years, no complaints: http://www.trugrit.com/

staffwalker · Post by **staffwalker** » Thu Apr 09, 2009 2:19 am

Yes, Trugrit is an amazing place to buy belts. I just called a couple of weeks back to ask if they could have me some 42" belts cut down to 3/4" wide. Since they had to cut them I assumed they would be expensive and take a while, not so, three days later I received a dozen at a buck fifty each which is about the same price I pay for the standard one inch ones. Highly recommend them for belts.

bob gilbert

Post by **KurtHuhn** » Thu Apr 09, 2009 10:40 am

In a glorious episode of thread convergence, you can get them from McMaster-Carr. Catalog page 2628 for plain aluminum oxide - which is all you need for wood. They carry an entire range of belt sizes, no doubt something to fit your needs.

Now, as far as belt flexibility goes - I don't know. I almost never use a belt grinder without a platen or contact wheel, and when I do, I want it to be fairly stiff. I do not use a sanding setup like the one you linked to, so I don't have any experience in that regard.

Olivier · Post by **Olivier** » Thu Apr 09, 2009 2:15 pm

I find that the overlap joints causes unwanted vibration and tends to bump the workpiece away from the contact wheel every time it passes. Some belts are spliced with a thin carbon fibre strip. Works like a charm. It is also of utmost importance that the belt is perfectly lined up otherwise you will end up with a belt that runs all over the place. IMHO DIY is not worth the effort. Buying proper belts will surely reduce the risk of injury. Machines like these at http://www.herbst.co.za/machines/basic- ... el-grinder are easy to build and can use 2"x72" and 1"x72" belts and a variety of sizes contact wheels. If you need the dimensions and basic info on such a machine I will be more than happy to assist you. I have templates for a very similar machine which can also be modified easily to suit your needs.

Tano · Post by **Tano** » Thu Apr 09, 2009 3:06 pm

Thanks for all the tips, Guys. I'll ponder this further and see what happens.

Alan L · Post by **Alan L** » Fri Apr 10, 2009 4:21 pm

If you really want to do the Rainer method and keep a hand behind the belt while shaping, you just about have to use the J weights. I use that method from time to time on a KMG 2x72 grinder with the slack belt attachment, available from http://www.beaumontmetalworks.com.

Keep in mind, though, that if your skin hits the edge of the belt it's kinda like touching the teeth of a running bandsaw blade, but not as messy.

Sort of a combination papercut/burn with some flesh removal involved. If you run the belt slow enough to be able to keep a hand on the back (due to heat buildup) you'll get away with minimal loss of blood, though.

I've taken to wearing a kevlar glove on that hand when I use that method, as it cuts down on the ouchies.