What Size Belt For A Diy Belt Sander

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mattthemuppet2

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hey all,

I really shouldn't be thinking about this as I have far too many projects and far too little time, but the idea of making a combo belt disk sander has been tickling my brain for ages. Partly because I was given a bunch of steel and alu disks (8in?), some with a diamond coating, as they were being thrown out of the Geo department, partly because I'll soon have a spare 1/3hp motor with a 5 step pulley when (hah!) I put a treadmill motor on my Walker Turner drill press.

General plan is to have the motor behind the sander, with a belt running to a common jack shaft, which drives the disk and the bottom roller of the belt. Single pulley on jackshaft, 5 step pulley on motor and a sliding hinge type thing to both tension and align the drive belt. Sanding belt will hang off the side of a tower made out of 4 pieces of 1in.sq tubing from my old TV antenna and the rollers will most likely be ~2in wide, due to some scrap pieces I have that would suit. I won't be using one of the 3 roller+ designs as that's a way beyond my fabbing abilities.

Question is - what's a commonly available 1 to 2in wide belt size? As I can build to suit (within reason), I'd rather go for a size that a) works and b) is common (+ therefore cheap). I've heard 2" belts are better than 1", but that's about it. Also, for general use, most likely knocking edges off cuts (metal and wood) and prettying up crappy surfaces, what sort of grit would you recommend? I have a 100grit white norton wheel on my bench grinder for grinding bits.

thanks!

bah, should get back to work now :(
 
thanks Toolmaster, plenty of different options for that size from what I can see. Any opinion on an everyday all round grit or is that a piece of string type question?
 
I think I'd go 1" wide and save the 2" for when you build a 2x72. I have the 2x72 and feel like I should build a 1" x ?? for knocking off burs etc.
 
I would go to ebay first and source out different sizes of belts up to 4" widths in industrial cloth backed grades-----find the best bargain on a large quantity and then build your sander to use them----I have very good 3" and 4" wide belts in different grits--so they will be used in my build----the coarser grits are better because they cut nice and will wear smoother after much usage---I will never have to buy extra belts again ---one belt disk sander I made is 6 x 102 vertical and about a 15" disk sander and also has a 4" x 16" drum sander------Dave
 
Hi, with a 1/3 hp motor, I think I would go with a 1x42 belt. I built a 2x72 belt grinder with a 2 hp motor. It seems like it has the right amount of power.
Jamie
 
Given your description and limitations, I would also go for a 2 X 48" belt. They are widely available, fairly cheap and come in every grit you will likely use. They make them in Zirconia, ceramic, AlOx so you will have what you need for whatever you grind.

The splice in belts have a shelf life of about a year, give or take a few months. Old belts will often snap at the splice and may injure you when they do so try to buy what you need at the time and buy new when you have a lot of grinding to do. A small amount of stick wax lubricant applied to the belt will reduce clogging and help the belt cut better and wear slower.

If you can, I suggest you consider making a really good tool rest for your grinder. It should be steel to reduce any tendency for the piece being ground to snag. Ideally, the tool rest should be indexable to those angles you plan to use the most. If possible, include a slot for a protractor.

Most importantly, you need a really solid platen that is dead flat and resistant to wear - I use a Pyroceram liner over a piece of O-1 ground steel and it will stay flat for many years of hard hobby shop use.

1/3 HP is on the weak side. I can bog down a 1/3 HP belt sander just grinding HSS tool bits. If you can, use something near 1 HP for this size belt. Variable speed would be ideal so you can slow down when using fine grit belts.

I would also leave enough room under the lower wheel for a pan partially filled with water - it catches the debris and cuts down the dust you breathe.

Speaking of lower wheels, use a contact wheel if you can afford it. A 5" or 6" wheel would be a good size and will allow you to do really heavy stock removal at need.

For tool grinding, I like a 34 grit AO belt and a 60-80 grit belt for general use. Belts are available up to 600 grit and finer. AO is fine for general work; Zirconia will last longer and get more done but they cost more.
 
My grinder is a 2 x 60. I can easily rip a belt down to narrower widths if I need to get into a tight spot. You might want to build your grinder with lots of adjustment so you can use multiple length belts.
 
hmm, lots of interesting points, thanks everyone! Hadn't really thought of the power issue, the motor is (will be) a spare that I'll want to keep, so I figured I might as well use it! It'll have 5 speeds and I can work out the right size pulley for the jack shaft from that. I'll have to measure the pulleys on the WT motor, but I think that they're around 1.5, 2, 3, 4 and 5in give or take. If I use a 2in jack shaft pulley and a 2in drive wheel, I should get 1300, 1750, 2600, 3500 and 4375rpm on the belt, which with the 2in drive wheel should = 680, 900, 1400, 1800 and 2300sfpm. Not a huge range, but for what I'll be using it for, it should do. I always keep my eyes open for treadmill motors, so the motor might get replaced at some point.

Sounds like 1x42 would probably be the best for this size motor, but it shouldn't be hard to make a 1" and a 2" wide platen if I upgrade the motor later to use 2x48 belts. Planning on using pyroceram too with a mild steel backing. Tool rest will be steel and as robust as I can make it. Not sure about the protractor as I'll have that built in on the disk side, but tiltable would be useful. Most likely I'll still be using my bench grinder for HSS bits, but it wouldn't hurt to rough them out on this first. The 1" belt might be better too for those awkward inside corners and I'll have the disk on the other end for larger straight edges.

Good call on the multiple belts too!

Mike, cool tip on the water pan - is this for the belt to run through or as a dust trap?
 
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