Saw is throwing fine dust when milling.

[pike it alot]

So i'm running a 660 w/MKIII and i'm milling dry spruce and my saw dust is a fine powder.I remember a very experienced miller said it should not be like that.I havn't milled in a couple of years but before I was milling birch which is a much harder wood and it wasn't taking half as much effort as it is now.I was running ripping chain and then tried convential and had about the same results.I'm thinking I don't have my depth gauges set deep enough,but not sure.HELLLP!

 

[darren_palms]

Just sawing in general if you are getting fine sawdust then you chain is getting dull or your rackers are to high.

 

[pike it alot]

both chains are sharp.I'll try bringing the rackers down even more.Thanks

 

[excess650]

Bob's rule of thumb, raker depth 10% of gullet width. Keep the chain sharp!

 

[hamish]

If your feed rate is decreasing or your discharge is changing you are fighting a dull or inefficent chain, yet also your climate and species being milled may be a factor.

Bet your logs are frozen at present as are mine, make a big difference, regardless of the sharpness and efficency of ones chain.

 

[BobL]

Post a close up side on pic of a cutter and I'll pass my "evil" eye on it.

 

[Trx250r180]

Im getting fine chips also with my 660 mounted to a norwood mill,im getting nice looking boards,i sem tp get better boards with skip tooth square over full comp square or round,on a 12 foot log om getting 4 passes for a tank of fuel,is that normal,i just got this mill and have lots to learn still ,my boards were 14.5 wide also,on some fir im getting fine black dots after wood sits a bit indoors,is that from bar oil ? Or can wood mold that fast ?

 

[pike it alot]

I'll try and get some pics on here tomorrow for your "evil eye" Bob.I just finished bringing the rackers down and sharpening the ripping chain and going to try another run with the mill after work tomorrow.I have always had a bad habit of forgeting to bring down my rakers.I haven't done much milling,most of the time just cutting firewood.In my opinion cs milling is one of the most enjoyable things i've ever done ,looking forward to doing and learning more.

 

[BobL]

Im getting fine chips also with my 660 mounted to a norwood mill,im getting nice looking boards,i sem tp get better boards with skip tooth square over full comp square or round,on a 12 foot log

Sounds like a raker problem again - a 660 on a 14.5" wide cut should make lovely fat chips.

om getting 4 passes for a tank of fuel,is that normal,i just got this mill and have lots to learn still ,my boards were 14.5 wide also,on some fir im getting fine black dots after wood sits a bit indoors,is that from bar oil ? Or can wood mold that fast ?

I've never cut fir but I know that if you sharpen the chain and leave the metal dust on the chain it can react with tannin in the wood and turn black but in your case I would suspect some sort of mould.

 

[mtngun]

on a 12 foot log om getting 4 passes for a tank of fuel,is that normal

No. I normally use 1/2 - 3/4 tank per pass.

im getting fine black dots after wood sits a bit indoors. Can wood mold that fast ?

Mold, especially in your humid climate.

 

[Trx250r180]

No. I normally use 1/2 - 3/4 tank per pass.

Mold, especially in your humid climate.

i wonder if the bar oil is making it mold ?i have an auxilury oiler for the bar tip ,the boards ive left outside dont seem to mold ,just if i bring them in the shop to dry faster by the wood stove


on my rakers im at .030 ,if i cut rounds it makes nice chips ,just when i rip im getting the finer chips ,ive tried grinding a round chain to 10 degrees for ripping ,that chain went pretty slow compared to a 25 degree square chain ,maybe im not pushing hard enough when i mill ,the bar seems to chatter if push too hard so i go pretty slow to get a nice cut here is a mock up of the mill ,i have mounted to my car trailer now for the flat deck with a 16 foot ladder for a track View attachment 278974 View attachment 278975

heres what my chain looks like View attachment 278976

 

[BobL]

i wonder if the bar oil is making it mold ? i have an auxilury oiler for the bar tip

I've never heard of that before

,the boards ive left outside dont seem to mold ,just if i bring them in the shop to dry faster by the wood stove

Mould likes warmth

on my rakers im at .030

Get yourself a filoplate depth gauge and/or some vernier callipers.
The raker should be about 1/10th of the gullet width.
If the gullet is 0.5" wide the rakers should be 0.050" - yep that much
The ratio of gullet width to raker depth depends on many factors.
I would imagine in fir at 14.5" wide 660 could easily deal with a 8:1 ratio used. This means if the chain is new when the gullet width is 0.25" the raker should be set to 0.25/8 = 0.3125 or 0.03"

,if i cut rounds it makes nice chips ,just when i rip im getting the finer chips

That is normal even with a well sharpened chain but your cut widths are so small

ive tried grinding a round chain to 10 degrees for ripping ,that chain went pretty slow compared to a 25 degree square chain

How slow do you mean - did you time any cuts?
Did you lower the rakers to suit the changed angle?
It should go marginally slower as at 10º the cutter chops the fibres at almost 90º whereas at 25º there is some slicing action happening. However, 25º also creates a slightly wider kerf which slows down the overally cutting speed.

,maybe im not pushing hard enough when i mill

You should not need to push much, it's a sign the top angle cutting angle or hook is not sufficiently aggressive but then again if the rakers are too high then no amount of TPCA will help.

the bar seems to chatter if push too hard

That's a sign the rakers are too high.

heres what my chain looks like

Can't tell much from that shot, when I say "side on" I mean like this.
It does not need to be that magnified but it does need to be fully flat side on.

I get a better finish using just semi chisel than either full chisel or square ground chain. Sharply pointed cutters as used by either full chisel or square ground chain will leave scratches in the lumber whereas semi chisel will at worst leave wide scallops.

4 passes per tank sounds unusual - you are going WOT the whole way right?

 

[Trx250r180]

here is a side angle ,thanks for the help with this Bobl View attachment 279033 View attachment 279034 View attachment 279035 i think i just took 2 swipes off each raker with the file .right around .025

this is a semi skip i had in my pickup but ground the same as my full skip ,cutters have real close to same material left


4 passes per tank sounds unusual - you are going WOT the whole way right?
i have been going about 2/3 throttle ,without the end of the bar supported on this mill its a little jumpy at wide open ,im trying to think up some kind of bracket to keep end of bar from flopping ,make more solid like an alaska mill

 

[pike it alot]

Just got through trying out the mill after bringing down the rakers some more and holy smokes the saw almost pulled itself down the log,very smooth boards and used at least 50% less fuel,if not more.I was also getting 4 passes down a 8'-10' log of about the same size.

 

[BobL]

OK here are your raker angles

On this one your raker angle is ~3.3º ie dust making territory
A Carlton file-o-plate raker setter generates an angle of ~4.5º which is the bare minimum I would even think about using on any CS.
For most cutting (milling or cross cutting) I start my 880 with full comp at 6º - that's a gullet width to raker depth ratio of 10:1.
For smaller Aussie hardwood logs I use 6.5º for any softwoods I use 7.5º

This one has an angle of ~7.3º - NOW we're cooking!
For a 660 on narrow cuts I would take it to 8.5º - if you go
I use a digital angle finder (DAF) to measure mine but I don't use it every time I set the rakers. I set them at home in my shop with the DAF but in the field I swipe them every 3 or 4th touch up which on my logs are after almost every big cut.

BTW I think it is worth rounding the rakers over and not leaving any even slight corners on them. The rakers do bite into the wood and corners on rakers create resistance which takes away from cutting power. Also clean out the gullets so the sawdust flows easily out of them.

i have been going about 2/3 throttle

WOW - no wonder you have such good fuel economy but this is not right, you absolutely have to run the CS flat out - that is what they are designed to do, at 2/3 throttle the saw won't be getting the cooling it needs (ie fan moving too slow) and will have very little power to do any work. Two strokes only have any real OOMPH at close to WOT.

 

[BobL]

Just got through trying out the mill after bringing down the rakers some more and holy smokes the saw almost pulled itself down the log,very smooth boards and used at least 50% less fuel,if not more.I was also getting 4 passes down a 8'-10' log of about the same size.

Excellent . Read my post above and adjust accordingly - using the method I describe and you will maintain good cuttings speeds until the cutters start breaking off the chain.
You can keep reducing the rakers until the chain starts to really grab and vibrate the and maybe even stall the engine. Then back it off from there a bit.
Chain companies don't want you to know any of this because they want to sell you new chains.

 

[pike it alot]

Well here's some pics BobL.When I brought the rakers down I shaped them the same as they where originaly.Would I be better of angling them like the pics you show?

 

[BobL]

Well here's some pics BobL.When I brought the rakers down I shaped them the same as they where originaly.Would I be better of angling them like the pics you show?

Looking a lot better, so - how does it cut?

Raker shape doesn't matter too much as long as they have some sort of smooth curve.

In the first picture the right hand cutter looks like it has a lot more "hook" or a greater "Top Plate Cutting angle" than the cutter on the left. If the cutters facing one way have more hook than those facing the other way the saw may cut preferentially to one side.

Your raker cutting angles are around 8.3º, if the rest of the cutters have the same hook as the right hand cutter I expect that chain will be pretty grabby and produce a fair bit of vibe but give them a try and see how you go.

If you want to pick up a few seconds per milling pass then clean the cutter gullets out of any excess metal as this helps the chips to flow easier out of the cutter. Well that's what the racing boys do :msp_biggrin:

 

[runningflenser]

many thanks to BobL

Man BobL really has some good input info. I've been reading these old posts b/c I also am running a stihl ms 660 on an alaskan mill cutting 28 to 20" oak. I'm getting fine dust clogging my bar oil port. I'm running brand new stihl 3/8" skip tooth chain on a 28" & 36" bar. Maybe I should take the rakers down on this new chain? Many thanks to BobL for the work into the pics and excellent information.

 

[BobL]

Man BobL really has some good input info. I've been reading these old posts b/c I also am running a stihl ms 660 on an alaskan mill cutting 28 to 20" oak. I'm getting fine dust clogging my bar oil port. I'm running brand new stihl 3/8" skip tooth chain on a 28" & 36" bar. Maybe I should take the rakers down on this new chain?

As well as gullet width, the optimum raker depth or angle depends on the wood, and width and saw power/torque. I reckon starting at a 6º raker angle and working it up from there. I used 7.5º on those recent short (<4ft) small diam (<18") hardwood logs I cut up earlier this week with my 441, and could probably have gone to 8º.

Just watch out that when you go too high the chain will get really grabby, there will be more chain vibe and finish might not be as good.

Many thanks to BobL for the work into the pics and excellent information.

I'd like to be able to give the credit to my dad who took me bush many times while he was felling trees from when I was about 6 years old. I used to do his touch ups from when I was about 9 years old, but I can't give him the credit because he use a fixed raker height/depth and that's how he taught me to file and he sometimes used to blame me when the saw didn't cut. Chains were to be thrown away when they still had many hours more cutting left in them but he wasn't paying for chains out of his own pocket.

It was only in the last 5 years that studied how chains work, read the Carlton chain manual and worked out what the Filoplate raker adjuster was doing did I work out what was going on.