Home Made Expansive Wheel

This visual article was made by Mr.Carlos Eduardo Klering of Nova Petropolis, Brazil. This expansive wheel is meant to be used on an ordinary bench grinder where you would normaly use grinding stones or buffing wheels. With this device you can use several kinds of sand belts with diferent grits for grinding, sharpening or restoring damaged edges of your favorite knives. It's all a very good solution for low budget hobby knifemakers.

For better understanding of all visitors we will use the metric measure system. If you would like to convert measures just use google or one of the several tools available onb the internet.

We advise you to take all protective precautions when dealing with any kind of machinery. The Brazilian Bladesmiths website and the author take no responsability for any injuries one might inflict to his or herself fabricating or using this device. Be very carefull when grinding or sanding knives.

Have fun!

Jeff Velasco


List of components:	1. a piece of EVA 170x170x50mm 2. a 12mm drill 3. a mill cutter (8, 10 or 12mm) 4. 50grit hardbacked sand paper	5. drill press 6. band saw or hand metal saw 7. bench grinder or small buffer

	Here we have some basic plans for the wheel. The standart EVA you will find is too thin and for most sand belts available on the market you need it to be 50mm wide. The solution was to glue another EVA layer on the bottom of the block. You can use any sort of general use cement. Ask for the hardware store guy what should work best. After you have glued the two layers you will have a 50mm thick block. Mark the center and from there use a string or a drawing compass to make the circle. Use a hand or band saw to rough cut the edges until you have something as close to a circle as possible.Use a hand or band saw to rough cut the edges until you have something as close to a circle as possible
	This wheel's diameter is160mm. I use it on a 1/2 HP grinder and it holds enough but it's not very precise. Remember EVA is kind of soft so I don't advise wheels any bigger or much more power on the grinder. Now measure the grinder's shaft and choose your drill. My shatf is 12.5mm so I used a 12mm drill to make the maim hole on the center of the circle.That way the fit will always be tight.
	Your grinder must have a limit on the shaft screw, so we must bring down the side so we can make it fit properly. You don't need a milling machine, just a mill cutter on a drill press and steady hands.Take into consideration that you need room for a washer and the nut. Here I used a 10mm cutter. The limit on my grinder, the washer size and the nut brought me to a 25mm cut into the wheel.
	See that the cut was smooth and that it's flat enough to keep the wheel from woobling.
	Now atach the wheel to the grinder and check for proper fit.
	Turn on the grinder and use a 50 grit sandpaper with hard backing to make sure the wheel is completely round.
	Now mark a second circle inside the outher circle. This will be the guideline for the next drilling process. A 160mm wheel is farily big so if the "teeth" are to close to the center the wheel might desintegrate, or if they are too far away it might not expand enough. Since EVA is cheap, you might want to try more than once and see what's best for you. I do recomend a distance of the outher circle between 20mm and 25mm.
	Set an angle of aprox. 45 degrees and trace another line. That will be the guide for the teeth cuts.
	Start drilling. You might want to use a 10mm drill here.
	It should look like this when finished. Those "teeth" are the reason why the wheel expands.The cuts MUST be made in the same direction the grinder turns, that way the air will get in the holes and make the teeth expand and the wheel will get tight on the sand belt.
	Start cutting using the lines you traced before.
	Try to use a band saw, but if you don't have one and can't find someone who has one, you can try to use a hand saw. Be extra carefull to cut it evenly and straight.
	Here is the wheel turing on the grinder, ready to receive a belt. After you are finished use a sewing measuring ribbon to find out the circunference. Add to that 5mm and you will have the lenght of your belts. Call your belt suplier and have him cut the proper lenght and glue it for you.
	Be carefull not to run your wheel without a sand belt for too long. It will tear itself apart in a few seconds. Here is a 3D drawing of the wheel. Have fun!
	Thank you very much!

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