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[4]

Band Saw Sharpener

January Project of the Month [3]
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f350ca

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#1
Started this project some time ago. Managed to loose any drawings I made so pretty much starting from scratch with some pieces I'd already built.
My sawmill uses a 1 1/4 wide band saw blade. There are places that sharpen them but having to take them there then go get them would get old real quick. Commercial grinders are available but don't fit my pocket book. So here we go.
I had the grinding head built, used the motor and wheel from a chainsaw sharpener. The case was cut out on the plasma table so there had to be drawings.
The head moves up and down to follow the tooth profile, on a set of bearings at the back.

IMG_4030.jpg

Made the blade guides this week from some mystery stainless that I had. Machined reasonably well.
The blade will slide between the two side plates. The gap is adjusted with those two brass assemblies, the outer jaw is spring loaded against the adjustment. The back of the blade rides on two sealed bearings.
Need to machine a little off the top of the guides to get to the bottom of the gullet.

IMG_4031.jpg

A 12volt gear head motor will advance the blade and that aluminum disk will be a cam to raise and lower the grinding head as it follows the tooth profile.
The pivoting arm will connect the two via an adjustable link to the head. The adjustment will set how much is ground.
IMG_4032.jpg

IMG_4034.jpg

Still working out how to determine the shape of the cam. Present thought is to make a dummy grinding wheel that can rest on the blade. As I advance the blade just mark the rollers position on the cam, then machine to the marks. I made the follower arm with a 3 to 1 advantage to make the cam less sensitive. The teeth are only about 1/4 deep so the cam will have a 3/4 inch lobe. Will see how it goes.

Thanks for watching

Greg
 

brino

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#2
Cool Greg!
I'll be watching for the next instalment.
popcorn.gif
-brino
 

f350ca

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#3
Made some progress on the mechanism to advance the blade while grinding.
Had to cut down the stainless shoes that guide the blade. The shaper makes easy work of it. Took light .03 cuts.
The blade feed in action.

I made the finger that pushes the blade from .03 stainless, silver soldered to the shaft. Seams to be too light, you can see it flexing.
I must have been bored or got carried away in a moment or hour or two of exuberance and over machined the part that links the rod to the eccentric. But I guess it does look pretty.
IMG_4040.jpg

Greg
 

TTD

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#4
But I guess it does look pretty.
Looks pretty, indeed! Nothing wrong with a little bling every once in awhile…makes the tools feel good about themselves ;)

Really nice job on the whole system, Greg. Much beefier than the sharpener that came with the Norwood mill I had here (mill only had a 7/8” wide blade. though).

As for the finger-flexing issue, what if you revamp the end a bit & substitute the stainless with a hardened pin of sorts that fits nicely in the root of each tooth? Was thinking something like a 3/16” - 1/4” diameter shoulder bolt would work well. Even an 1/8” shoulder bolt would work…not a whole lot of force needed to advance the blade. That’s how the Norwood sharpener was set up & it worked really well.

You could have the main arm oriented so it was either off to the side of blade & a pin/bolt screwed or welded to the side of arm to catch each tooth (Norwood style), or if you wanted it a bit beefier to reduce the twisting force exerted on pin, make the end of arm a “split-finger design (arm directly over blade like you have) with pin/bolt captured at both ends.
 

f350ca

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#5
I like the pin idea Todd. It doesn't take much push to move the blade till I get playing with the adjustments. Tightened up the gap between the guides and bound the blade, thats about when the finger started flexing. For now I shortened it and its working.

Greg
 

Billh50

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#6
Wonder if this would work for sharpening bandsaw blades.
 

f350ca

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#9
The grinder motor Im using came from one of those Bill. They work great on chainsaw chain where your only grinding the chisel then filing the racker to compensate. With the bandsaw they grind the whole profile to keep the gullet depth correct.

Greg
 

f350ca

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#10
Made an attempt at cutting the cam that controls the grinding head. Made static measurements on the plate with a washer beside the follower. Got the up profile correct but it drops too fast. Need to ramp the down motion where it cuts the face of the tooth as the advancing mechanism is retracting.

Greg
 
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