Kerf thickness?

Okrafarmer · October 29, 2012, 12:45:48 AM

I am using factory new Woodmizer Double-hard blades. I am quite pleased with their performance in log, so far. However, I am a bit stunned that the kerf is so wide. Right out of the box, the kerf seems to be about 3/16 of an inch or just a hair less. Definitely more than 1/8 of an inch. I was under the impression that some circle mills have a 1/4 inch kerf. So where is my big kerf savings? I keep thinking the kerf should be only 1/8 or so.

And how do you spell curf? My spell-checker doesn't like it. Cerf? Kurf?

beenthere · October 29, 2012, 12:59:33 AM

Seems the primary goal is good sawing from the band.

Kerf is right.

Okrafarmer · October 29, 2012, 01:34:42 AM

Quote from: beenthere on October 29, 2012, 12:59:33 AM
Seems the primary goal is good sawing from the band.

Kerf is right.

I'll add it to the dictionary.

There, done. :P

LeeB · October 29, 2012, 01:55:40 AM

How much is your blade fluttering? Buggered up v-belts and trash under them can cause a lot of flutter. Also insufficient tension on the band, or too much. Could also be set wrong. I usually get about 1/8" kerf or just a tad less.

Okrafarmer · October 29, 2012, 01:56:55 AM

I keep seeing this reference to a .087" kerf. In the book put out by/along with Woodmizer, for instance. But my kerf is at least .15 and may be more than that. Maybe .175, which would be twice the .087. Maybe a different style of blade would help. Just wondering.

Okrafarmer · October 29, 2012, 01:57:51 AM

Quote from: LeeB on October 29, 2012, 01:55:40 AM
How much is your blade fluttering? Buggered up v-belts and trash under them can cause a lot of flutter. Also insufficient tension on the band, or too much. Could also be set wrong. I usually get about 1/8" kerf or just a tad less.

Hmm-- you could be right. Maybe the old v-belts need to be replaced. Good idea.

Bibbyman · October 29, 2012, 02:51:54 AM

You didn't mention blade thickness. .055 blade will take a wider kerf than .045.

Set will also change the kerf. I don't recall the set on factory new 7° DoubleHard blades but it may be more than other grinds.

We tend to use .100 for out kerf setting using 7° .045 DoubleHard blades.

Chuck White · October 29, 2012, 05:32:39 AM

Seems like a big kerf Okra!

I use .045 WM blades and set at .025, so .045 blade thickness plus .025 set, each direction equals a kerf of .095.

Less than 1/10 of an inch!

ladylake · October 29, 2012, 06:03:33 AM

Surly not the blades, how much down pressure are you running. Should be 1/4" for good blade control. Not enough or none would let the big wheels variations make a bigger kerf. Also bad guide wheel bearing or out of round guide wheels . Steve

hackberry jake · October 29, 2012, 06:24:22 AM

I think it might be the blade. Too much set would be my guess. I got a wm blade with not enough set once. Okra if you could just take some of your set off and send it too me then we'll both be making (the right amount of) sawdust! 8)

Nomad · October 29, 2012, 07:41:10 AM

Okra, if you're getting more than 1/8" kerf it's got to be more problem than just tooth set. Guessing you're using .045 bands, you'd need .040 set to get a 1/8" kerf. (.045+[.040x2]= 0.125) Something else has to be not right.

ladylake · October 29, 2012, 07:51:19 AM

That's right, the set to cut 3/16 would look nasty. Teeth would be pointing just about straight out. Steve

POSTON WIDEHEAD · October 29, 2012, 08:00:23 AM

My blades are .045. When I saw a cant wanting 1 inch boards, I set my simple set at 1- 1/16 inch. That will give me a perfect 1 inch board.

ladylake · October 29, 2012, 08:10:37 AM

Maybe try pushing your feed rate more. Steve

jcbrotz · October 29, 2012, 08:33:57 AM

Check your blade guides tilt, me best would be your rollers are not parallal with the bed. How much is your blade moving/fluttering when it running and not in the log? What blade are you running.

drobertson · October 29, 2012, 08:34:56 AM

Okra, if your blade is a .055, the kerf should be in the neighborhood of .110. this is what I set the Lt 70 I was working on for my friend. It was cutting on the number. I set mine for .093, using .042 blades, again it cuts on the number. I have experimented with more set, in the .030 range, it starts to get a bit raggid.

Kansas · October 29, 2012, 09:11:36 AM

We run heavy set, due to the fact we are cutting cottonwood a lot. But I would never figure more than 1/8 inch, and usually its less. There is one thing. When you measure a board, don't ever use the tape measure with the end on it. go up the tape a little ways and use that. That is something we have to make sure we drill in to the new guys that you don't just check the thickness by using the end of the tape. That steel thing can get way off. When you are cutting a bunch of half inch deck boards, and its off an 1/8 inch, due to wear, it can really mess things up.

Okrafarmer · October 29, 2012, 09:48:31 AM

Good advice, guys. The mill is cutting very straight and true, so I'm happy with that, but now it seems from what you're saying that some things need to be adjusted. I probably need to arrange for a WM rep to come and do one of the magical service calls and get all the stuff spiffied up and teach me a few things. Until then, I'll keep cutting straight lumber and loosing a little extra sawdust. I can replace the Vee-belts, and maybe that will help. They are looking a little rough.

Road Runner · October 29, 2012, 11:02:57 AM

Okra, Woodmizer is having an open house in Newnan, GA on 11/3 and 12/8. You might call them (770-251-4894) to see if they will be doing an alignment demonstration like they did in SC last week along with a quartersawing demo. This would be a short trip for you and watching someone who knew what they were doing was time well spent for me.

thecfarm · October 29, 2012, 11:54:31 AM

I have no idea what thinkness or kind of WM double hard blade you are using,but I have one and did not notice any diffeance with my other bands.To tell you the truth I don't even know if I can tell which is which now.

MartyParsons · October 29, 2012, 06:15:31 PM

.042 thick blade is .090 thousants
.045 thick blade is .096
.055 Thick blade is .110
1/8" is .125 so all of the above blades are less than 1/8" total kerf. Good rule is double the blade thickness = total Kerf loss.
Marty

tyb525 · October 29, 2012, 06:45:30 PM

Okra, on my mill, if the blade is too loose and the feed rate too slow, it will cause the blade to vibrate up and down and make the kerf bigger.

A major cause of this is a dull band, or simply too slow feed rate. It forces you to saw too slow, and due to the slow feed rate the blade heats up, expands, and reduces tension on the blade.

Okrafarmer · October 29, 2012, 06:57:10 PM

I haven't noticed much difference in kerf between a sharp blade and a dull blade.

Roadrunner, maybe I can make it to one of those WM demos. Sorry I missed the SC one. Wish someone had told me.

learner · October 29, 2012, 10:44:54 PM

I've just been running this LT40 SHD for 3 monthes now but have learned a few things about it. Your blade guides can Really affect your cuts and kerf. I suggest making sure the blade is running level accross your rails and guide rollers. Also make sure your feed is running true. Any up or down movement of your head can change your blade angle, tension and cut(you get waves in your cut).
I haven't figured out how to put pics on here so. Check at the base of your vertical masts. The upper guide rails and wipers. WM reccomends cleaning the upper guide rollers daily. I suppose because if something gets stuck to one of the rollers it can cause the head to move up over the obstruction and change your blade height from the rail. Hence a wavy cut and change in the kerf. Just a thought.