|Project by Div||posted 08-24-2010 09:28 PM||18976 views||13 times favorited||19 comments|
I promised some people that I will post this contraption, so here it is. It is a shop built sharpener for the band saw blades I use on my sawmill. The blades I use are 32mm wide with a 22mm pitch.
The machine was built with mild steel off cuts from the scrap bin. I have a metal lathe and could make the machined pieces but these are not many. I found the grinder motor at a junk yard and modified the shaft to accept the grinding wheel. The feed motor is a 12 volt wiper motor from a car. Now I can’t drive my truck when it is raining…
It took me quite a few evenings to figure the mechanisms! I ended up building a mock up in timber to confirm and refine the mechanisms. The hardest part was establishing the correct shape for the cam. This determines the “path” of the grinder wheel over the blade.
I’ll try and explain the operation: The feed motor advances the blade via that threaded rod thing that goes through the aluminum block. There is a fork at the end of the rod with a pin through. This catches on a tooth, advances the blade a certain amount, then returns to catch and advance again. At the same time and in sequence with the advancement, the cam causes the grinder motor to move in such a way that it follows the profile of the tooth. Thus it grinds the tooth evenly along its shape. The height of the grinding wheel above the blade can be adjusted by the knurled wooden knob. This determines the amount of grind along the top of the tooth. The length of the forked rod can also be adjusted. This sets the amount of grind along the vertical of the tooth.
I hope all that makes sense…
A tank underneath the machine contains water which is pumped with a tiny aquarium pump onto the blade as coolant. Therefore the 3 switches: one for feed, one for grinder, one for coolant pump.
The machine works a treat and I have used it for years. I get supersharp blades that let me mill 3mm veneers. If like me, your wallet is thin, build your own!
-- Div @ the bottom end of Africa. "A woodworker's sharpest tool should be his mind."