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heating circle mill blade

Started by leastofthese, December 12, 2010, 05:29:43 PM

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leastofthese

hello, i'm new to milling and i have a meadows portable mill. it seemed to be sawing fine and the other day it got so hot it dished in to the log side. dished so bad it was rubbing the blade guard on the inside. it turned out i had lost all my lead, so i corrected that problem, but now it seems to heat pretty quick. i was sawing some big butt cuts and thought tension might be causing some of the problem. so i went to some small logs, 12" to 20" ( the butts were like 30" or so) it seemed like it was doing better, then started heating up again. i did sharpen teeth also. so i got a couple of questions, how do you tell if you shanks are worn( spilling dust in the cut, i see it coming out between the blade and the log)?  and how much heat or how many times heated til i need to get it rehammered. i forgot to mention its heating at the eye area. carriage and husk are connected so i don't think there has been a whole lot of misalignment between the two. and like i said it was running fine. any advice would be appriceated.

Ron Wenrich

A saw doc will tell you that heating a blade just once may be enough to cause it to need hammering.  But, that hasn't been my experience.

How did you lose your lead?  Are you sure you have enough right now?  Sometimes when your saw dishes, you might nick your headblocks, and that will damage your teeth on one side.  That takes a lot of filing to get rid of the problem.  What may be happening is that you damaged your teeth on the log side, so your saw will lead out.  The saw will always lead towards the longest side of the tooth.  This opens your saw and allows your log to rub against the eye, and that heats the saw.  This is my best guess of what has happened.  It only takes a few teeth to get the saw to pull.

The cure is to either change teeth, or swage out your existing teeth and get both sides even.  A spider gauge helps to even up the sides.

Shanks shouldn't be a problem, if the saw was sawing before.  Shanks should last for about 1 million bf or more.  They'll start to get rounded, but you can sharpen them up with a file.  If you change shanks, you will need to get the saw hammered.  If you have bad shanks, they'll show up pretty quick when you get into frozen wood. 

The only other spot to check is your saw guides.  When you set your lead, you should have loosened your guides up so the saw wasn't rubbing.  If your saw is pushing on the guides, you'll not get a good reading on setting the lead.

The way to set lead is to start out with a tooth at the saw guide, and measure the distance.  I usually adjust the carriage to a whole number.  Then, take the saw to the board splitter side, push the carriage ahead, and measure the same tooth to the same headblock.  You should get the whole number plus a fraction.  That fraction is your lead.

If your guides are pushing on the saw when you're sawing, then that is like putting lead on or taking it off.  If they aren't tight, they can move when you're sawing. 
Never under estimate the power of stupid people in large groups.

leastofthese

thanks mr. ron. my teeth were damaged after the first heating where the saw was rubbing.  i filed them and it seem to help. it sure enough cut a lot better. it only seems to heat when i get into  say 10" cuts. i also read somewhere(after i had already changed my bits) that u should change bits one at a time so that u put the shanks back in their original locations. i did not do this, but i think it was sawing good after that.

NMFP

Re swage the teeth.  The width of the tooth isnt wide enough for the body of the saw to clear the kerf.  For example, if you have a .25" thick blade, the width of the kerf should be wider than that.  Circle mills like this are swaged to gain clearance for the body of the saw just like bands are set to provide clearance for the body of the band.

What size blade are you running and what style teeth are you using?  Also, what gauge is the saw?

If your lead is correct, saw is hammered correctly, teeth are sharpened and swaged correctly, your saw should run as cool as a cucumber.

Let us know how you make out.  Swaging isnt a hard job, just a little time consuming?  Are you using and andrus sharpener or a jockey sharpener.

Good luck with this project and let us know how you make out.

Thanks.

NMFP 8)

bandmiller2

Leastof,Ron pretty much covered it.Have you set your lead before, and do you know how much you need?? The way I determine lead is to set it between 1/32 and 1/16" then cut a good sized cant.If the back of the saw  mark the cant heavily at gigback not enough lead. If the saw tends to pull the cant away from the last headblock too much lead,it really shows up on the last board. Are your bearings good on the arbor? Frank C.
A man armed with common sense is packing a big piece

leastofthese

thanks for the replies. i did not swage, and i hand filed.2 1/2, 9/32 in 8ga.plate. i did set the lead but probably more like an 1/8". back of the saw hits not really on the gig but when the upstroke first hits the log. hope that makes sense. sawing pine in louisiana. thanks

Ron Wenrich

Lead is what it needs to be.  Although I've seen numbers of where it is supposed to be set, sometimes it needs to be set heavier.  I had one mill that needed 3/8".  But, you start at the low side and work your way up.  You may have it set a little to high, which will have your saw lead into the log. 

When your saw is running, is it running against the guides?  I run mine so that the board side is snug.  But, sometimes that changes when I change species.

Although your track and husk are tied together, your track to the either side of the husk must be in line.  Other wise you'll be putting pressure on the saw as your carriage makes a small arc.  And, your bearings on your carriage can't have any play.  Your carriage may be changing a little position as it travels.

Hand filing can give you problems.  I've hand filed for 30 years.  But, I still can get the angle on my tooth wrong.  If you make the inside angle too fat, you'll have heat problems.  I use a jockey to keep my angle honest and hand file to give it a better edge.   I just hand file during the day and use the jockey about every 3rd or 4th time.  It does make a difference.

The other thing that can happen is that you get the angle on the front of the tooth off.  You may have a tendency to file the tooth longer on one side than the other.  The saw will lead in the direction of the long side. 



Never under estimate the power of stupid people in large groups.

leastofthese

i also found an 1/8" jog in the guide track in about the center 6 feet of the mill. right where the husk is. this doesn't seem like much, but it probably is enough to heat my blade ain't it. thanks again.

bandmiller2

You've probibly located your problem.Seems strange that a big, heavy, powerfull mill is so sensitive to minor adjustments.Level and verticle headsaw are important too.Frank C.
A man armed with common sense is packing a big piece

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