prototype bandsaw blade sharpener

[roghair]

Here is a short clip of my prototype bandsaw blade sharpener I put together. Main purpose of this prototype was to test if I could keep the Gullit shape accurate combining the horizontal movement (sinus) and the vertical movement (cam). If someone is interested I can explain in more detail how I made the cam.
For the grinder I used a cheap chainsaw sharpener ($ 20 or so). The up-down/ blade transport is still manual which is OK for now. I can always add a motor to that.
The result is encouraging, but there are some points for improvement. The band I sharpened seems very sharp, but before I do the others I will test this one on the mill. I leave the set for what it is now, but that is an other project I guess  ;)

http://www.youtube.com/watch?v=N3t3RPE63Ck

[Delawhere Jack]

Roghair, I am in the process of building a sharpener as well. I am using a 1/2hp motor which will power the grind wheel via a belt and a shaft mounted in pillow blocks.

I have an idea of how I will make the cam, but I would be interested in hearing your method. I may make the pivoting lever longer on the cam side, perhaps by a 2:1 ratio. This would allow for a little less precision in the cams, (mostly it would compensate for my aging eyesight), and would provide some mechanical advantage for the motor driving the cam.

After watching your video, maybe I'll set mine up with a hand crank on the cam. Finding a suitable motor to drive the cam has been delaying my progress. I can always add a motor at a later time when I find one that suits my mizerly budget.

[Peter Drouin]

Nice job, but I think you need a lubritant so the blade tip don't burn then turn blue, 

[woodyone.john]

D J,when I was rebuilding my wm sharpener and wanting it to be mains powered I bought an old singer sewing machine for $10 complete with optional electric motor and speed control.Try to adapt it to the wm cam assembly was too onerous for me in the end. My engineering tools are an angle grinder and a stickwelder.As a direct drive the motor might be too fast but belt driven and geared down I'm sure it would work.cheers john

[Ljohnsaw]

Just a general comment.  I see you doing a straight grind on every tooth. I have no experience with these blades (yet), but I was assuming an alternating grind to match the offset such that the side of the tooth cuts, like a chainsaw.  Am I way off base on that assumption?  If all you need is a straight grind, then that sure simplifies the process!

[Dave Shepard]

I don't know anything about sharpening, but that's a pretty slick contraption you've made there.

[roghair]

Ijohnsaw, I think this is what all the sharpeners do. After the grinding they set the teeth, altough some people prefer the other way around  ???

[roghair]

Delawhere Jack, I just answered a PM, here is part of it:

Before I started this project a watched a lot of youtube clips several times.
I saw that ¼ of the cam (90 deg) was for the Gullet, 90 deg to raise the grinder above the tooth, 90 deg to lower to the point of the tooth and 90 deg to grind the hookangle. In order to measure the gullet I blew it up big time and measured the depth every mm. 22 points in total (7/8" is 22,2 mm). I put these values in an Excel spreadsheet and added values for the up, down and hookangle quarters. those values can be linear and are not critical since there is no grinding in the up and down quarter and the grinding in the hookangle quarter takes place without horizontal movement.
If you have all the values in an excel you can choose to insert a so called 'radar chart' which basically gives you the shape of the cam. You can make the base circle bigger to add a fixed nummber to each value. 

Now the big challenge is to have the right horizontal movement relative to the cam position during the 'gullet quarter'. To achieve that, I made the 'connecting rod' (that pushes the blade) adjustable in relation to the cam. You can rotate and fix each one independent on the axle. By turning the axle slowly you can define the push/ pull from the connecting rod relative to the cam position and fix it. A bit trial and error. I had to grind the cam a little while on the axle to achieve the exact gullet shape.

[Bandmill Bandit]

the CBN grinder system works very well IMHO.

The wheel profiles available pretty much cover any thing I have needed to this point.

But good luck in your project.

[WmFritz]

Looks like you've about got it figured out.. good for you roghair.  . Keep us posted.

[drobertson]

Not to shabby rouge! I would try to increase the speed,(time spent in the face of the tooth) just to reduce the heat if it is even a problem, looks like a lil heavier cut than I make, but results are in the pudding, nice work!   david

[Delawhere Jack]

Delawhere Jack, I just answered a PM, here is part of it:

Before I started this project a watched a lot of youtube clips several times.
I saw that ¼ of the cam (90 deg) was for the Gullet, 90 deg to raise the grinder above the tooth, 90 deg to lower to the point of the tooth and 90 deg to grind the hookangle. In order to measure the gullet I blew it up big time and measured the depth every mm. 22 points in total (7/8" is 22,2 mm). I put these values in an Excel spreadsheet and added values for the up, down and hookangle quarters. those values can be linear and are not critical since there is no grinding in the up and down quarter and the grinding in the hookangle quarter takes place without horizontal movement.
If you have all the values in an excel you can choose to insert a so called 'radar chart' which basically gives you the shape of the cam. You can make the base circle bigger to add a fixed nummber to each value. 

Now the big challenge is to have the right horizontal movement relative to the cam position during the 'gullet quarter'. To achieve that, I made the 'connecting rod' (that pushes the blade) adjustable in relation to the cam. You can rotate and fix each one independent on the axle. By turning the axle slowly you can define the push/ pull from the connecting rod relative to the cam position and fix it. A bit trial and error. I had to grind the cam a little while on the axle to achieve the exact gullet shape.

WOW! You Sir have many talents!

You've given me some good insights on making the cams. My plan was to allow a stationary contoured grinding wheel to trace a new band, and measure the movement of the pivot arm on the cam end. The complexity arises from the circular actuation of the blade pusher as it relates to the height of the grinding wheel. But, if I measure the height of the pivot arm at the point where it should contact the cam, then I can step it off in horizontal increments of band advancement and mark those on a cam blank.

This is probably not the clearest explanation I could provide, but I've had a couple beers tonight.... :

Thank you for sharing your design.

JC

[Chuck White]

Only thing I see that I think should be changed is the feed speed.

To much time in any one area and you'll burn the blade!

Other than that, you've got a great thing going there!

Two thumbs up:   

[stefan]

That is one nice looking sharpener!
And, very impressive work on how to find out the cam profile.

[Nomad]

     Roghair, that workmanship is as impressive as the mill you built! 
     As suggested above, I'd consider speeding up some.  Also, it appears you're taking a rather heavy cut on the face of the tooth and less so on the back.  Try it the other way around.  Just kiss the face, but take a bit more from the back of the tooth.  And great job!! 8)

[bandmiller2]

Roghair,very impressive,the hard part is done just find a small motor with a gear reduction or a separate gear box with a motor belted to it.Its a demo but a little lighter cut would be easier on the bands and is all that's needed.I find that even cams for certin tooth profiles require a couple of cuts before they clean up the whole gullet.Is your hook angle adjustable.? A DanG good job mate. Frank C.

[roghair]

... The complexity arises from the circular actuation of the blade pusher as it relates to the height of the grinding wheel. But, if I measure the height of the pivot arm at the point where it should contact the cam, then I can step it off in horizontal increments of band advancement and mark those on a cam blank....
JC

That might work indeed. Keep in mind that if the circular actuation is making half a turn (push forward) half of that horizontal movement is roughly linear. Use that linear part to grind the gullet. Otherwise you have to deal with a non-linear horizontal speed while making the vertical movement for the gullet. That is why I use one quarter of the cam to make the gullet. Mention the first part of the push forward, the blade is not moving (during the non-linear part). I realize this might not be clear at all, sorry for that.

[roghair]

It's been a few days ago, but thanks for the input from you all. Is it a problem if you grind slow and got some blue-ish metal? The reason the feed is slow is because it was manual and I turned the wheel too slow  ;D. Now I have a 24V motor with gearbox to feed the blade and turn the cam. I only need to find (or make) an adjustable powersupply for it.
After grinding some teeth the grinder was taking too much from the face and less from the back  of the tooth (as mentioned by Nomad). Reason for this was the adjustment screw was moving by itself. This problem has been resolved now. There were some other parts with too much play that needed modification.

Frank, the hookangle is adjustable:

[Delawhere Jack]

Roghair, I understand what you said, in a general sense.... :D

My build is nearly complete. I have designed mine so that an oversize cam blank can be installed offset slightly, I will fasten a pencil on the pivot arm to mark the cam as I drag the grinding wheel (not turning) over a tooth.

I looked into the Excel "Radar Graph" feature that you mentioned. Although I will not be using the graph to make my cam, it is a very handy tool that I'm sure I will use in the future.

One more trip to the hardware store and I should be ready to go!

[roghair]

DJ, looking forward to the pics!!

[Delawhere Jack]

Well it's finally done. Well, it is functional anyway. My advice to anyone planning to build one of these..... buy one instead.  ;D

The amount of hours, and the number of trips to the hardware store, Grainger, my dads' place to use his much better equipt shop, etc, added up to a LOT of hours... :-\ But, I just finished my first band and it looks pretty good.




 



 

[customsawyer]

Great job on the build. All you need is a little tweaking to get it right. Here is a video of my sharpening. Hope it helps you on yours.

http://www.youtube.com/watch?v=qJOL0xb6VsY&feature=player_detailpage

[Delawhere Jack]

I can't take much credit. I basically copied the Cat Claw design. There are still a couple items I need to improve, like the band feed arm. Currently I've got a coupler nut on each side of the crank block. I'll change that to a heavy spring on the back and a theaded knob on the front, and fine thread (Just like the Cat Claw!)

I saved enough money on this, maybe I'll go a little crazy and buy a setter. Hmmm.... Nah, I'll build one! 

[roghair]

DJ, looks great! Are you turning the cam manually, like I do? What is the Cat Claw design (don't we all copy what works well  ;D. We say 'better a good copy than a bad design')

I finally have a little motor and power supply for the feed/cam. Hope to be able to install it today and shoot a new video.

customsawyer, seems you have a whole production line running in your grinding shop. I recognise a setter and sharpener from Cook's, what is the other sharpeners brand?
Which one do you prefer; the one that follows the gullet with a narrow grinding wheel (like Cook's) or the one that makes the gullet profile with the shape of the grinding wheel?

[roghair]

Now with motor feed:

http://www.youtube.com/watch?v=qorfoH2lwAw