Optimising an 090 for milling

[Big Beech]

Ha, yeh if only!! was a late night but an early morning get up over to east Sussex to see the good ladies grandparents on the farm. so, sorry for the phone tap talk crap.
but basically, I did not move the vane to max out at 11k. I will see how we go tomorrow morn first and then may do a redo tach n tune on site. but the thought of taking the dam starter box on and off will be a pain no doubt. we will see :msp_smile:
hopefully will get the video on the go to.

thanks for your help Harry and sorry to derail your initial thread
simon

 

[mtngun]

I'm hoping the high(er) chain speed of the 8 pin will mean I don't have to lower the rakers too much

Why ? What is so important about surface finish ?

If the board is to be planed, then surface finish won't matter. Surface finish won't even effect how much has to be planed since there is usually more variation in thickness for other reasons when using an Alaskan mill.

If the board is to be used a rough lumber, then once again surface finish won't matter.

You'll be hitting the limiter the whole time or will need to drop the rakers a lot resulting in increased stresses on the chain.

Huh ? I've never broken a 3/8 chain while milling, and my milling saws never run at max rpm.

The OP seems to assume that an 090 has a surplus of power. Wrong ! :msp_thumbdn: There is no such thing as a surplus of power for milling. If your powerhead is not working hard while milling, then your chain is not sharpened correctly.

The OP assumes that there is something wrong with aggressive rakers. Wrong ! Aggressive rakers are a good thing for milling.

 

[harrygrey382]

Why ? What is so important about surface finish ?

If the board is to be planed, then surface finish won't matter. Surface finish won't even effect how much has to be planed since there is usually more variation in thickness for other reasons when using an Alaskan mill.

think I'll have to contend this. I haven't fully decided how I'll be finishing, but at least some will be for a dining table. So I'm wanting full width slabs. I doubt I'll be able to find a planer or thicknesser around here that will take these widths so may be doing it by hand, not sure yet. Either way, assuming I mill them flat, consistently and dry them properly (I know all big assumptions) the better the surface finish the less work later. I disagree about there being necessarily more variations for other reasons. True sometimes other things go wrong, but not always. If everything goes right (and I've had plenty of boards where it has) all that needs cleaning up are the saw marks.

so, if raker height does affect surface finish like a lot of experienced millers say it does - I'm interested. I'm not saying there is anything wrong with aggressive ones, I've just read several times they make the finish rougher. It would have been ideal (too good to be true maybe?) if someone had made a grading of raker height vs surface finish in a given situation!

The OP seems to assume that an 090 has a surplus of power. Wrong ! There is no such thing as a surplus of power for milling. If your powerhead is not working hard while milling, then your chain is not sharpened correctly.

I wasn't assuming this. I was assuming the 090 revs lower and has more torque than say an 880 or 660 (fair assumption, eh?). And I was asking how people who have used one for milling make the most of this situation seeing as chains and sprockets these days are designed for higher revving less torquey saws that are the norm

 

[mtngun]

some will be for a dining table. So I'm wanting full width slabs. I doubt I'll be able to find a planer or thicknesser around here that will take these widths so may be doing it by hand

Why not use a router sled ?

if raker height does affect surface finish like a lot of experienced millers say it does - I'm interested. I'm not saying there is anything wrong with aggressive ones, I've just read several times they make the finish rougher. It would have been ideal (too good to be true maybe?) if someone had made a grading of raker height vs surface finish in a given situation!

When running VERY aggressive rakers (8 - 9 degree angle) and the Malloff grind, I typically see washboarding on the first pass, sometimes on the 2nd pass, but then smooth cuts on subsequent passes, as the cutters gradually lose their sharpness and take smaller bites. So it's not just a question of rakers, but also sharpness and cutter angle.

Aggressive rakers allow the saw to cut freely, without pushing hard on the mill. Typically people who run standard rakers will rock the saw from side to side to try to get the chain to bite.

I commonly see 1/8" thickness variations on boards (from one spot to another) due to the Alaskan mill, regardless of surface finish. The Alaskan mill and the guide board are not perfectly rigid, things flex and wobble, and the bar flexes, so you get some variation. Then when the board dries it often cups a bit. If I'm going to plane a board, I usually take off at least 3/16", regardless of surface finish.

I was assuming the 090 revs lower and has more torque than say an 880 or 660 (fair assumption, eh?). And I was asking how people who have used one for milling make the most of this situation seeing as chains and sprockets these days are designed for higher revving less torquey saws that are the norm

Most of what we know about milling chains comes from Will Malloff, who used a 090. The Malloff chain grind also works well on high revving saws. It cuts rougher, too. Malloff aimed for speed, not surface finish.

Generally, anything that makes the chain take a bigger bite -- raker angle, cutter angle, cutter sharpness -- will produce a rougher finish, but cut faster. Anything that takes a smaller bite will produce a smoother finish, but cut slower.

 

[BobL]

When running VERY aggressive rakers (8 - 9 degree angle) and the Malloff grind, I typically see washboarding on the first pass, sometimes on the 2nd pass, but then smooth cuts on subsequent passes, as the cutters gradually lose their sharpness and take smaller bites. So it's not just a question of rakers, but also sharpness and cutter angle.

I think the reason washboarding happens more likely on the first (and also last) few passes on a log is the cuts are narrower and wood is slightly softer so the cuts can be made at a speed that enables the chain speed to synch with the cutting speed. If it happened just due to chain sharpness then I would see it every time I touched up or swapped to a fresh chain.

This is my go to picture about this.
Same saw, same wood, equally sharp chain, the only difference is the right hand cut is 30%^ wider than the left.
BTW rakers are only at 6.5º on these cuts.

 

[820wards]

I've been reading that, and it's pretty good. He doesn't talk about sprocket sizes, and just says he sets his rakers at .045 and makes no mention about surface quality. The 090 has a lot of talk and I know will have no problems holding revs with an 8 pin 404 in 32" of cut. But I was wondering if others have found this is enough chain speed or they could get more, and the effect of raker height on surface finish.

Thanks Gerry that's great. So I'll start out with an 8 pin sprocket, then drop the rakers incrementally keeping an eye on the finish. Do you know how many revs in the cut your motor is making?

A stock 820 PowerBee motor operating RPM range with a 3/4" intake with a stock exhaust is around 7600rpm if I remember correctly give or take a 100rpm. I have installed a 1" bore intake/carb, carbon fiber reed valves and a 2" exhaust. Without putting a tach. on the motor I think I'm easily in the 8,500rpm range WOT. With .042" rakers I still have gotten smooth cuts even with the black Oak I have milled.

Do you know how a racing sprocket will hold up to milling? This is my second mill - the first one I made on your plans and was great, but didn't survive the move from UK to Australia. My new one is also using your plans. I've got a nose oiler for it but haven't used it yet - been using the 070 on it and the bar just wasn't getting hot. Might hook it up for the 090 though.

I think your 090 will do quite well with an 8pin sprocket since you have the torque of a large motor. I usually run my mill, a .134cc motor at 3/4 throttle when milling. I have also welded in an additional baffle on my fan-recoil shroud that forces additional air over the cylinder head to keep the engine temp good over longer milling cuts, so I've never had excessive heating problems even in warm-hot weather. Your 090 is a great motor, take care of it and it will provide may hours of milling service.

Cool to hear you tried my mill design, good luck on your next build. Post us some photos if you can of your build.

jerry-

 

[splitpost]

bump

 

[harrygrey382]

yeah hanging out to get milling but it's not going to happen for a couple of weeks... Liking the 8pin 404 for bucking though

 

[820wards]

yeah hanging out to get milling but it's not going to happen for a couple of weeks... Liking the 8pin 404 for bucking though

With a shorter bar for bucking and an 8pin sprocket, your 090 should tear through firewood. Have fun! I have three logs to mill myself, but it's been too hot here to mill and I don't want the wood to be checking on the ends.

jerry-

 

[WidowMaker1]

generally always running 8 tooth .404 on my 090, does it all with ease

 

[chunez]

what is the malloff grind everyone talks about? Is it just the matchbook trick to adjust the hook depth?

 

[J D]

what is the malloff grind everyone talks about? Is it just the matchbook trick to adjust the hook depth?

From the book...

Most people run closer to a 5° top plate filing angle as it reduces the chances of accidentally filing the top plate with a slight reverse angle

 

[chunez]

Thanks! So basicallu

From the book...
View attachment 1139419
Most people run closer to a 5° top plate filing angle as it reduces the chances of accidentally filing the top plate with a slight reverse angle

ok so the big difference is filing at 0-5 degrees instead of 10 degrees like most manufacturers sell? How does one adjust the inside/outside angles to 40°? Or that will just happen anyways when you file at 0°?

Also, this is just for full-chisel chains? I thought you wanted semi-chisel for milling because it stays sharp longer?

 

[J D]

ok so the big difference is filing at 0-5 degrees instead of 10 degrees like most manufacturers sell?

Adjust to what works for you & your cutting conditions/setup. Much the same as some will sharpen at 25° as opposed to the traditional 30°. 0° is what he found worked for him on the wood he cut. I run 5-10°

How does one adjust the inside/outside angles to 40°? Or that will just happen anyways when you file at 0°?

That is the top plate cutting angle or "hook". It is set by adjusting the angle your grinder comes down on or how low you drop the file into the gullet when hand filing. I have mine around 50°

Also, this is just for full-chisel chains? I thought you wanted semi-chisel for milling because it stays sharp longer?

Same applies to both. Both styles of chain have their advantages/ disadvantages much the same as x-cutting.

Take a look at the CS Milling 101 sticky, all your questions & then some will have been covered there... & probably several times over

 

[Lightning Performance]

I think every sawyer who's concerned about chain eventually finds what works for him and then converses with others with lots of experience to see what works for them. You're going to have to find your own groove first and buy Malloffs book if your clueless.
I run between °5 -20° top plate face angle. The rest changes according to many factors including chain sequence or cutter type.

 

[poleframer]

I milled for years with an 090. I built a mill very similar the the one posted by lwmibc in the "best beginner sawmill for wide logs" thread.
I did go through a couple top ends, I'd stick with the smaller sprockets and not push the saw to it's max. I really doubt you will see much difference in cutting speed, if you keep your chain sharp.
I also had a power feed made of a boat winch and a drill that helped my surface finish a lot.
Like a power feed on a lathe, it's more difficult than you think to move at a controlled steady pace. I would mostly set the drill speed by listening to the saw run, and board appearance. The surface of the boards really improves at a slower feed rate.
About 6-7 years ago I built a band mill, and like it a lot more for these reasons.
#1- fuel. I use a small diesel engine and can do more milling on a gallon of diesel than 5 gallons of mix. That 090 is a thirsty beast.
#2- noise. I wore ear plug under ear muffs while milling. People a mile away knew when I was milling.
All in all, the 090 is probably the best milling chainsaw there is.