Bandsaw Blade Sharpener with Indexer

[jteneyck]

After a gentle prod from one of our members I'm posting the bandsaw blade sharpener I recently built based on the original design by Derek Cohen.  Essentially, I copied Derek's sharpener approach and added a tooth indexer.  

Here's an overview shot:



I used a HF Dremel tool knockoff.  It's mounted to a right angle sled by drilling a 2-1/8" diameter hole at the edge of a small plywood bracket that screws to the sled.  The angle it's mounted at is about 22° which is the angle of the back of the teeth on my Woodmaster CT.  Sharpening is by means of diamond cutoff wheels that I bought from Amazon for cheap.  The sled rides against the bandsaw fence.  This is pretty much a copy of Derek's design.   

You could stop right here and have a workable system.  It's actually not hard to index the blade and then gently push the sharpening wheel against the tooth to sharpen it, index and repeat.  But I decided to add an indexing system to make it easier and to speed up the process.  The indexer is just a small strap hinge that I cut the end off to better register in the blade gullet, mounted to a piece of plywood with a runner that registers in the miter slot. 



A small shim under the hinge brings it up to the right height for the sharpening wheel to contact the back of the tooth where it needs to be.  

To use it you lift the blade:



When the tooth clears the indexer it falls into the gullet, and then you pull the blade down until it stops.



Now gently push the sharpener forward until it taps the blade.  A couple of gentle taps is all it takes.  I think maybe I removed a couple of the 0.001's, just enough to create a sharp beak on the tip of the tooth.  



How's it work?  Well, the cut quality was nearly as good as a brand new blade.  Moreover, the ease with which the board fed into the blade was noticeably less.  



My blade has 1.3 tpi, but I think this type of sharpener will work on blades up to at least 3 tpi although it might require some fiddling with the angle of the indexer.  

John

[cputnam]

Well done John! I love it! Beautiful synergy from folks on Woodnet: 1st Jack Edgar posted about using a Dremel on bandsaw blades, then Derek builds a positioning jig and then you add the indexer. Now I am trying to generalize the indexer to cover more blade tooth counts.

[John Mihich]

Time to patent it and make some money.

Good idea.  I hand hold my dremel.  Makes the blades sharper and last a whole lot longer

[Willyou]

You have done some nice work with this. However, I'm going to do a bit of nit-picking that some will say doesn't matter. I say it is important to maintain a consistent tooth height and by grinding the top of the tooth you are introducing the opportunity to make each tooth different. To prevent that, you need a support at the back of the blade to keep it from flexing backwards and you need a very precise stop on the grinder in order to grind a consistent amount on each tooth. The latter would be difficult to do using wood fixtures. Granted, using your method can certainly "improve" a seriously dull blade but lacks some important precision in order to maintain a smooth cutting blade. Think in terms of a hand saw that is jointed before final tooth shaping and sharpening.

Using a diamond coated cylinder grinder on the underside of the tooth (gullet) is a better way to go. It will sharpen just a well without as much risk of changing the tooth height.

[jteneyck]

You have done some nice work with this. However, I'm going to do a bit of nit-picking that some will say doesn't matter. I say it is important to maintain a consistent tooth height and by grinding the top of the tooth you are introducing the opportunity to make each tooth different. To prevent that, you need a support at the back of the blade to keep it from flexing backwards and you need a very precise stop on the grinder in order to grind a consistent amount on each tooth. The latter would be difficult to do using wood fixtures. Granted, using your method can certainly "improve" a seriously dull blade but lacks some important precision in order to maintain a smooth cutting blade. Think in terms of a hand saw that is jointed before final tooth shaping and sharpening.

Using a diamond coated cylinder grinder on the underside of the tooth is a better way to go. It will sharpen just a well without as much risk of changing the tooth height.

All true.  However, in practice I found the same thing that Derek did; you don't need to support the back of the blade or use a stop in order to get consistent results.  How can I say it's consistent?  Look at the cut quality.  Further, sharpening the cutting face of the tooth still changes the "length" of the tooth, no different than sharpening the back.  It doesn't matter which face you grind, it changes the length.  

I think sharpening the face of the tooth would be better, to be honest, but it's not nearly as easy to devise a simple jig to do so.  Manually sharpening with a round cylinder is beyond my skill set and I'm not going to ruin a $150 blade trying.  I'm looking for a semi automatic approach like what I showed.  Please develop one and show me how.  Thanks. 

John  

John

[Stwood_]

Sharpening just the top, you will eventually change the gullet. The blade may be worn out, breaking by then anyways. Blades can only bend going around a wheel so long, before cracking in the gullet. The gullet is sized to carry the waste out.

Do you have an auto sharpener for your band mill, or do you send those off?

Bandmill sharpeners sharpen the front and top of each tooth, keeping the gullet profile.

[Willyou]

I agree that we are talking very small differences. However, grinding the top WILL change the height of the tooth as measured from the tip to the bottom of the gullet or back edge of the blade. Grinding the underside may move the point back slightly along the blade axis, it will not change the tooth height but for a infinitesimal amount.

You can use a cylinder on the underside freehand very quickly and easily. You have to really push it to do something wrong. Try it on an old blade. The down side is that you need different size cylinders for different gullet sizes.

How will grinding the top change the gullet? Grinding a little on the underside will not change the gullet in any detrimental way.

I have no experience with auto sharpeners. However, I'll wager that they are designed to maintain consistent tooth height.

[jteneyck]

Sharpening just the top, you will eventually change the gullet. The blade may be worn out, breaking by then anyways. Blades can only bend going around a wheel so long, before cracking in the gullet. The gullet is sized to carry the waste out.

Do you have an auto sharpener for your band mill, or do you send those off?

Bandmill sharpeners sharpen the front and top of each tooth, keeping the gullet profile.

I built an automatic sharpener for those blades.  You can see a short video of it running here.  But it's a crude device; not one I would use for my carbide tipped Woodmaster CT, even with a diamond grinding wheel.  You only sharpen the face and grind the gullet.  That way the tooth height remains essentially constant, although the overall width of the blade slowly gets smaller.  After 2 or 3 grindings the blades break, usually around 10 total running hours.  

With regards to the CT, I don't care if the gullet depth slowly diminishes.  We're talking a few thousandths out of something like a 3/8" deep gullet.  If I ground the face of the tooth I'd be forced to grind at least part of the gullet, too.  I'd rather not do that, even thought it's technically the proper thing to do.  If I get even as little as 2X the useful life out of a CT before it breaks then I'm money way ahead compared to sending it out to be sharpened.  I believe Derek reported that he sharpened his CT 4 or 5 times before it broke or he retired it, I can't recall.  Time will tell if mine lasts that long. 

John

[Stwood_]

Yes. Saw your sharpener. Looks good.
My sharpener I had came from a RRshop that sharpened blades for the bandsaw that cut wooden beams on box cars. Yes, it was old.
I modified it so it would grind the tooth it was feeding. Previously it had a tooth between the feed pawl and grind stone, which after several sharpening's threw the teeth off. Heavy grind, light grind, etc.
I ground my own Woodmizer blades plus some others. It was adjustable don to 4t per inch.
Wished I had kept it at times, but I sold it with my LT30 Woodmizer mill.

[Timberwolf]

Well done John!  I love it!  Beautiful synergy from folks on Woodnet:  1st Jack Edgar posted about using a Dremel on bandsaw blades, then Derek builds a positioning jig and then you add the indexer.  Now I am trying to generalize the indexer to cover more blade tooth counts.

..........................
Theres a Youtube video floating around out there that is very similar to the one posted...The fellow has a lot of machines and jigs that he makes out of wood....Another fellow posted a video proving his NEW hand sharpened  { Dremel } Timber-wolf blade was sharper than a NEW Timber-wolf right out of the box...He made a sled with a pulley and weight..He timed how long it took to make the cut through the same board. The hand sharpened blade speed was very impressive. I hope I can find the videos..

Edit....
I did find the video of the indexing sharpener...I have seen several iterations of this design, but indexing to me is overkill, because I can sharpen  a 93" 6ppi blade in about twenty minutes on the saw using the "gullet" method with a round diamond burr in a Dremel.. and without "jigging up"...

https://www.youtube.com/watch?v=Ui16m3D90j0

And another good design.........

https://www.youtube.com/watch?v=Blf4kN0jDJs

This fellow sharpens his the way I started doing it nearly 15yrs ago...with a rotary burr, but this is not the video I was really looking for that showed how much sharper a blade can be compared to a new one of the same brand.

https://www.youtube.com/watch?v=1sE-LZ1D4gM