More sharpening advice

AaronS · February 01, 2024, 08:00:33 PM

Hi all, it's me again. Thanks for everyone's advice last time helping me realise my grinding wheel was way too worn down.

But unfortunately I'm still having sharpening troubles... I just can't get my blades to feel like they were from the factory! And I word it that way because I'm 99% positive they're properly sharp. No light reflecting off the tips, tiny burr after sharpening, super sticky sharp feel, etc.

In addition, I'm getting light blade chatter the whole way through the cut, which I assume is related.

The good news is that they're cutting very straight, even with the spruce. It's just harder to push and the lumber is a bit stripey due to the chatter.

I'm slowly going insane questioning everything... any and all suggestions would be greatly appreciated!

Joe Hillmann · February 06, 2024, 08:52:37 PM

Are you also setting them when sharpening them?

Are the blades just dull but otherwise good or did you hit metal/dirt/rocks before trying to sharpen them?

Have you tried looking at the blades under a magnifying glass? I found wearing a cheap $1 pair of reading glasses when sharpening lets me see things I can't without some magnification.

How many blades have you tried sharpening? Do they all have the same issue?

How many times has the blade been sharpened?

Can you post a picture of the lumber and the blade teeth?

PAmizerman · February 06, 2024, 08:58:33 PM

Sounds like a set problem. Not a sharpness problem

Gere Flewelling · February 07, 2024, 10:06:48 AM

I not sure what you have for a setter but if it doesn't give you a dial indicator reading on each tooth once it is set then you can't be sure you are maintaining the .025" set the teeth need to be set to. I would suggest you take a red or green Sharpie and color the top edge of a group of teeth being sure to color the entire gullet as well. Then set the teeth and then run them through the grinder/sharpener. If when you are done you see remaining sharpie color that means you haven't ground the whole tooth. I suspect you might see some color near the top of the back of the tooth. If the face and back of the tip of each tooth has color on it, it hasn't been sharpened. After that you need to de- burr the band. Especially the left/inner teeth. Many believe this is not necessary, but it is part of the sharpening process in my opinion. I use a 3/8" piece of hardened steel ground at a bit of an angle on each end to run by each tooth to de-burr them. I think an old sharpened wood chisel would do the same thing. If you follow these steps you should be able to saw straight and true. Good luck! Don't give up!

barbender · February 07, 2024, 02:48:03 PM

I've never had a blade that was sharp, feed hard. It should almost pull itself into the cut. No matter the set. A poorly set blade wouldn't start to feed hard unless it cause the blade to rise or dive in the cut to a point that the band was rubbing and causing resistance.

A dull blade can cut straight. When I had a manual push feed mill, I had a blade that was still cutting straight even though I could feel it was dull by how hard I was having to push. It finally broke from me pushing so hard on it, but it sawed nice and straight right up to that point.

I think your blades are still dull, or they have a negative hook. General makes a nice little machinists protractor that works great for checking your angles.

For an extreme example of what a nice sharp blade with a negative hook angle will cut like, take a new blade, turn it inside out and install on the mill so the teeth are backwards. Some of us have done this by accident when a blade supplier ships blades coiled the opposite direction from what out mill takes. Don't worry, you won't get far into the log😁

AaronS · February 10, 2024, 02:08:52 PM

Hadn't checked the forum for awhile, so just catching up now. Thanks everyone!

So the blade that was chattering turned out to be a set problem, yes. Bought a proper set of digital calipers and half of the teeth (all pointing one way) are overset 4 or 5 thou. Not sure how to unset them all without that unsetter I've seen a couple of times on here...

The others I checked and are all set properly. Yes Gere, the setter I use has dials, which seemed to be reading fine, not sure how that one blade got messed up.

Barbender, I measured the hook angle with a (plastic) protractor and as far as I can tell, it's right at 7 degrees.

Joe this is their first sharpening. I've done 2 or 3 from this new batch.

So I've eliminated the question of set and all that remains is that somehow I'm not sharpening properly... why, I have no idea. I think I might just take another trip out to my old blade sharpening guy and get him to look them over, see if he can tell me what I'm doing wrong.

ladylake · February 10, 2024, 03:33:08 PM

Post some pics, straight from the side and straight from the top. Steve

Gere Flewelling · February 10, 2024, 04:12:31 PM

AronS- You can make a set adjuster / fine tuner out of a 4" x 3/8" bolt. Put it in a vise vertical and with a hack saw cut down into the threaded end about the width of the hacksaw blade. Now when you find an occasional over or underset tooth you can use this tool to set down over the tooth and flex it a little in the direction it needs to go. Do this while it is being measured at the dial indicator. It doesn't take much to bring the tooth back into alignment. Once you learn how to use it, you will use it a lot. Note: this tool will not work on the Ripper brand blades as it will snap off the tooth. I found that out the hard way. I have to use a small pair of water pump pliers to grip the tooth near it's base and flex it. It works great on every other brand of band I have tried. The roller de-setters are great but usually are only needed when all or many of the teeth are over-set. I only use my roller de-setter on bands that have struck metal and are really messed up. The bolt tool will work on a sharpened band without dulling teeth.

Bradm · February 10, 2024, 10:27:59 PM

Quote from: AaronS on February 10, 2024, 02:08:52 PMSo I've eliminated the question of set and all that remains is that somehow I'm not sharpening properly... why, I have no idea. I think I might just take another trip out to my old blade sharpening guy and get him to look them over, see if he can tell me what I'm doing wrong.

Pictures would help and do you have a new and unused band that you can compare to? Please include closeup pictures of both the sharpened band and the grinding wheel. My guess is, without seeing pictures, is that your tooth face is still dubbed and/or you have ground the top down too much resulting in a shallower gullet with less room for sawdust.

ladylake · February 11, 2024, 04:03:24 AM

I make the gullet on mine shallower on purpose, cuts straighter. That is not the problem. Steve

AaronS · February 12, 2024, 09:13:39 AM

Gere, thanks for the tip about colouring the blades to see how I'm sharpening. Tried it on 3 teeth but unfortunately (or fortunately?) the grinding wheel smoothly hit the entire face and back sides of all 3.

I'll post some pictures below for y'alls consideration. This was just after sharpening and after I took a few passes through a cant to test it. Set measured between 19 and 21 thou. Still cut straight, but definitely not as easy to push as a new blade.

AaronS · February 12, 2024, 09:18:02 AM

.

barbender · February 12, 2024, 11:40:51 AM

3 of the pictures I can't see what I need to be able to tell if there is a problem. However, the blade in pic #2 has negative hook. Bad.

Get a picture of the teeth, from the top up close with a light on it.

ladylake · February 12, 2024, 12:55:35 PM

Also send a pic of how your stone is dressed. Does your sharpener have enough tension to hold the blade steady when sharpening. If not enough tension it could push the blade ahead when the stone comes down resulting in less hook. Steve

SawyerTed · February 12, 2024, 06:09:18 PM

It might be an optical illusion/camera angle that makes it look like negative hook. The blade certainly appears to have a peaked tooth rather than a hooked tooth in the photos.

Do you have a new blade with the same hook angle as the resharpened ones?

Take a careful tracing of 5 or 6 teeth on the new blade. Compare the teeth tracing to the resharpened teeth. It should be clear if you have negative hook. Your teeth on the Resharp should be very close to the tracing. If not, the comparison should give some clues on what's wrong.

You can also mount a new blade in your sharpener to check the stone shape and adjustment by lowering the stone in the gullet of the new blade with the sharpener turned off. Effectively using the new blade as a gage to check the stone.

Magicman · February 12, 2024, 06:21:00 PM

Saw blade tooth gauge for 6 different tooth profiles:
Part Number 065691

The section of blade on the right is a Turbo 7. I painted the gauge for quick reference; White = 10°, Green = 4°, and Red = 7°.

AaronS · February 13, 2024, 12:00:50 PM

Yes, you're all right :/

Took it to the sharpener and hook angle is yet again only 3 or 4 degrees.

He said it's nicely sharpened of course, but something is up with my hook angle.

I dressed the stone referencing a new blade, so I'm confident the profile is correct.

Something seems to have changed though... when I started sharpening months back everything was fine, but only recently have I started ruining my hook angle... could something have slipped or moved on the sharpener? It's Woodmizer's BMS25. I always check the angle with the template before I start and it's perfect.

Ladylake, I'm pretty sure it's tensioned enough... although I'm not sure how much is enough

doc henderson · February 13, 2024, 12:51:31 PM

I had a reference to set up at 7° and ended up with a neg. hook angle. for one I was trying to make the whole profile including the gullet nice and shiny/sharpened. second, I wonder if it required a setting at more of an angle to get the desired finish angle. I have been told to just barely skim/kiss the front and back of the tooth.

SawyerTed · February 13, 2024, 01:25:07 PM

It looks like the wheel is coming down on top of the tooth then grinding the face incorrectly. The side of the wheel should lightly grind the face of the tooth.

The pusher arm that advances the blade through the sharpener may need to be lengthened. That way each tooth will be pushed further past the grinding wheel and allow the face to be ground by the side of the wheel. Check the fastener that connects the arm to the cam just to be sure the arm pushes uniformly.

You've got the correct cam installed for the blade profile? I noticed the BMS25 has an accessory kit of various cams.

ladylake · February 13, 2024, 02:26:17 PM

Quote from: AaronS on February 13, 2024, 12:00:50 PMYes, you're all right :/

Took it to the sharpener and hook angle is yet again only 3 or 4 degrees.

He said it's nicely sharpened of course, but something is up with my hook angle.

I dressed the stone referencing a new blade, so I'm confident the profile is correct.

Something seems to have changed though... when I started sharpening months back everything was fine, but only recently have I started ruining my hook angle... could something have slipped or moved on the sharpener? It's Woodmizer's BMS25. I always check the angle with the template before I start and it's perfect.

Ladylake, I'm pretty sure it's tensioned enough... although I'm not sure how much is enough

Watch the blade a when the push arm is going back and the stone is coming down, it shouldn't move at all. Steve

Gere Flewelling · February 13, 2024, 02:51:58 PM

AronS-we are throwing a lot of advice at you on this subject and I am sure it can be a bit overwhelming. Thanks for acknowledging us when we respond. I have another bit of advice that I don't think anyone else has suggested yet. While sitting here watching my Cat Claw sharpener doing it thing I am wondering if you sharpener has an adjustment to apply friction to the sides of the band and hold it there when the advancing arm is resetting to the next tooth. I have forgotten to tighten mine down once in a while and noticed that the band will back up slightly when the advancing arm releases and is moving to the next tooth. That would certainly give you the negative hook everyone is talking about. I watched a YouTube video on your sharpener but didn't hear band clamp tension mentioned. Seems like it must have something to keep it in place and I do know that this is a wear area on my sharpener. Maybe on yours as well. Fingers crossed!

AaronS · February 13, 2024, 08:16:55 PM

Thanks for everyone's suggestions!

Ladylake and Gere I'm going to take a look and see whether the tensioner is doing it's job or not. And you're welcome Gere

Thank you for the encouragement.

SawyerTed, yes I put the 7 degree cam on right after I got the sharpener.

And Doc Henderson, yes I'm tempted to set the angle more than I'm supposed to just to see what happens. With an old blade of course

AaronS · February 14, 2024, 02:31:10 PM

Well tension is still good, pretty much as tight as I can make it. What's even stranger is that when I took a piece of tin and cut into it with the wheel while it was clamped, I got a perfect 7 degree angle. Some pictures below (the top line was traced of the top of the blade clamp). I noticed a tiny bit of sway side-to-side of the whole grinding wheel assembly, but I can't get the hinge any tighter... could that be it?

SawyerTed · February 14, 2024, 02:46:03 PM

The sharpener doesn't appear to be pushing the teeth far enough past the stone. The stone looks like it is coming down on top of the tooth.

The arm that pushes the blade needs to be longer. It should have an adjustment to push the tooth further.

Bradm · February 14, 2024, 03:19:12 PM

That's a massive radius on the grinding wheel where it sharpens the face. Grinding wheels are designed to breakdown in the areas where they work so if you take a 0.010" cut the wheel will start to develop a natural 0.010" radius and over time, as you try to compensate for it will cause it to develop a bad negative hook resulting in a dubbed (flattened out to negative profile) tooth face.

If you look at the shallow profile grind above, it looks as if the radius on the wheel is riding up almost the full tooth face.