iDRY Vacuum Kilns

Sponsors:

Amount of cutters...

Started by sigidi, June 20, 2005, 11:41:23 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

sigidi

Can I run more cutters on my slabbing bar? currently I have 13 pairs I think for a 1375mm (4'7") cut

QuoteIANABI think the question of skip chain is based on how many cutters are going to be in the wood at once. Each cutter needs a certain amount of power to drive through the wood and there will be an optimum number for each powerhead. Say for example you have 10 cutters in use with a 20 inch bar, but you then change to a 40 inch bar. Will the saw drive the 20 cutters now in use? Or are you better to switch to a skip chain and still have 10 cutters working properly?
Going to skip chain on the 20" bar would only give you 5 cutters in use, this would make for more vibration  and probably slower cutting. With REALLY big bars the same logic applies and you end up with chains that have 8" between cutters.

A well respected and trusted friend, who has a huge amount of knowledge, time and experience with chainsaws - 20+ yrs scratched his head at the Lucas skip chain. Said something about running full comp, not sure if I understood him correctly, but given what Ian said regarding amount of cutters in the cut at any given time and power of the engine to drive an amount of cutters, how do I know if I can run more cutters in a length on chain for my bar?

I know Ian runs a Peterson, but can't remember if he has a slabbing bar or not. My local rep for Lucas has mentioned some trialing he has done regarding the chain on the slabber and said something  along the lines of a full width cut almost 1400mm wide, should proceed at about a metre a minute. Now I never get this kind of cutting with my slabber.

Would a few more cutters mean faster cut's? How can I find out if the engine can handle more cuts without buying rolls of chain and testing out different combo's? Would more cutters mean smoother finishes or rougher finish to the cut? What info do I need to work out amount of cutters the engine is capable of driving?

Any help would be great!!
Always willing to help - Allan

maple flats

Run the question past the mill mfgr. They most likely have proven specs on many diff saws as to how many cutters you can go. If that fails check with the saw mfgr, tell them the situation and get their take on it.
logging small time for years but just learning how,  2012 36 HP Mahindra tractor, 3point log arch, 8000# class excavator, lifts 2500# and sets logs on mill precisely where needed, Woodland Mills HM130Max , maple syrup a hobby that consumes my time. looking to learn blacksmithing.

rebocardo

> Would a few more cutters mean faster cut's?

No, I would think it would mean a slower speed. When using chain more cutters mean the same or slower cutting. More cutters means more wood or dust in the kerf which has to be cleaned out. More cutters means either a more powerful engine to achieve the same quality or the same or faster chain speed. Full comp on a smaller mill will produce a smoother cut, it goes slower too. The stuff I have before cut looks planed.

I used the skip to cut the cants and bark off and then switched to full comp low profile to make the final boards when the majority of the wood was gone after the cants where made.

You are talking a cutting width almost five feet wide! I can't see running chain full comp in that unless you have huge horsepower or are cutting small pieces. In that case I imagine chain speed is the most important thing. I have noticed when chain speed on the smaller mills slows down you start getting chain marks in the wood.

Lucas works in a competitive enviroment and you are using an engineered solution. I imagine if full comp would benefit production and quality they would at least offer it as an option. Plus, they probably have a engineer (with a degree) on hand for design and quality. I would not modify or add a different chain without passing it by them first.

If they tell you they experimented with full comp and it does not improve the quality and only slows down the mill, then you have your answer.

The additional benefits of a smoother or faster cut might not outweigh a broken wornout chain or excessive wear on the motor or components.


sigidi

All valid points thanks, rebocardo
Always willing to help - Allan

jokers

Quote from: rebocardo on June 22, 2005, 10:32:25 AMWhen using chain more cutters mean the same or slower cutting.

Maybe that's true when milling or cutting very large resinous wood but it's not true for bucking and felling the typical hardwood. I have no experience with chainsaw milling.

If you don't believe me or want to consider the simple mechanics of more teeth through an area in a given time, just consider what chain complement the racers use.

Clearing chips from the kerf is a function of two components, enough space for the chips so that they don`t impede cutting action and enough teeth and rakers to keep the volume of chips produced moving. Fewer cutters eqaul fewer chips. Empty space between the cutters means lower efficiency.

If a powerhead will not pull a certain length bar with full comp chain in hardwood, you need a bigger powerhead. I have first hand expereince with this on bars up to 36", beyond that the circumstances change a little and chip clearance does become an issue on felling cuts.

Russ

StihlDoc

In general, full skip and semi-skip chains require less feed force than full compliment chain when using 36"+ bar lengths that are fully buried in the cut and cross cutting softwood. In milling applications, the chip produced is relatively small in comparison to the chip produced when cross cutting and does not usually require the extra space between cutters that full skip chain provides. Keep in mind that not every cutter is performing a cutting action as it feeds through the kerf. The cutting process is quite random due to the chain speed and the bouncing of the cutter through the kerf. When using full compliment chain, only every 4th or 5 th cutter is actually perfoming a cutting action as it travels through the kerf.

sigidi

So StihlDoc given what you said, do you think I ahould be able to run more cutters on the chain and if so what would be the disadvantages or advantages of running more.

Like you mentioned, in milling/slabbing cuts the 'chip' isn't a chip, more so dust. Lucas do have a chain for slabbing less than 750mm (30") which is 2 on, 3 off and then the 2 on 5 off for over 750mm.

Although as mentioned earlier in the thread Rebocardo mentioned you would think Lucas would have a very qualified fella crunching the numbers to make sure the best fit???
Always willing to help - Allan

StihlDoc

Based on my experience, I suggest using full compliment chisel chain filed at a 10 degree top plate angle and the depth gauges lowered to 0.8 mm. With Australian hardwood I would keep the depth gauges at 0.65 mm. The only advantage I have had running full skip chain is for slabbing because the dirt in the bark dulls a chain quickly and full skip chain is faster to sharpen because of the fewer amount of cutters. I find that full skip does wear the bar rails out faster vs. full comp chain but I am willing to sacrifice the bar wear vs. the faster sharpening. I currently rip with STIHL 63PM Picco chain filed at 10 degrees on an 066. Cutting performance is slightly better than full comp 3/8" chisel but it leaves a much smoother surface finish on the lumber and the narrower kerf gives slightly more yield. It may not be durable enough though for that dense hardwood you mates have in the land of Oz.

sawmillsi

Sigidi,

I think both Warren and Geoff Lucas are engineers (and very good ones at that).

They are the ones who developed (with/for Oregon) the 5 off and 2 on cutter pattern that Petersons now use as well.

I think, like most things developed/invented, this has come about through first a lack of product on the market (to fill a void) and secondly through lots of trial and error.

I am confused, if Lucas and Peterson both recomend this type of chain (and they both have lots of experience), why do you need to re-invent the wheel (or chain as it may be)?

To those who might be unsure about whats being discussed, its ripping accross the grain, not with it and not cross cutting. Chainsaws were never intended to do this action, only cut trees downa nd buck them to length.

Simon

sawmillsi

Hi STIHLDoc,

I agree with you about the 10 degree top plate angle and the 0.65mm depth cutter gauge, but about the chain - i have personally broken 3/8" chain on a 48' bar using a STIHL MS880 (about 13hp) crosscutting Australian hardwood (Iron Bark).

When slabbing with motors from 18-27hp, I think it would be mad to try and use chain other than 0.404" chain. Sure you loose more to sawdust, but think of the savings in hospital bills from the chain not breaking.

Simon

StihlDoc

Agreed. You gents have some very dense hardwood that we never see the likes of in the U.S. It's amazing that the saws, chains and bars hold up as well as they do in your Country.

Big Stan

I've read your inquirey..I can't find your mill type,horsepower and whether your  doing cuts perpedicular to the log.(straight across..hardest cut on any gear)
What species are you predominately cutting, also your log sizes your cutting.
I note your "pet hate" of striking metal ..a real major [I have typed a profane word that is automatically changed by the forum censored words program I should know better] when cutting salvaged timber..
After cutting about 20 yrs we bought a metal detector, about $600.00 incl GST
We have picked up a thin guage 3" nail at 20" depth , twice..in front of witnesses at Austimber 2004..Albury last year, both bought one, the head of a 2" nail at 10 " deep in a metre dia. Tassie Myrtle log, found lost important bolt in heaps of sawdust,star pickets overgrown in a log, heaps and heaps of nails, spikes..mango trees are the worst, highway side tree's..from politicians signs, market signs.
I beleive in em so much I approached the best manufacturer known and have become an agent..I'll sell you one @ a good price.
I agree with a few of your replies,there is some basics to be adhered to, but on the other hand, it's worth finding a suitable chain pattern for your various needs..
Australian timbers have amazing idiosyncrasies to contend with.
Regards, Big stan

sigidi

Sorry Stan my apologies...

runnning a Lucas 18hp with slabbing attachment, doing edge to edge cuts down the length of the log. so far I have slabbed, bluegum (forest red gum), white mahogony (yellow stringybark) red mahogony (red stringy) red ironbark, grey ironbark, spotted gum, cadaghi, and turpentine oh and Gympie messmate.

Most have pretty high density, mind you I think I have fallen in love with stringybark for it's smell, ease of cutting and great grain.

Size of logs is a tough one, I mostly slab from 500mm up to capacity of bar which is about 1350mm I think (when it gets too big I just trim it down with the 372 :D)

Metal detector - so far my metal detector is my eye's, which more often than not only work on my blade rather than the log >:( they have picked up a few close ones but also let go a few too many, luckily it has been on my own cutting so far and as such haven't needed to charge out customers. But by all means send me info on ya metal detectors...
                                                                   I just last week lost the slabbing bar drivehub nut whilst slabbing out in a field, under normal circumstanges I would have found it, but that day I moved the mill 5 times and each log was rolled over 180 deg, which meant that I covered the running path of the nut 5 different times. I figured I would buy one cheaper than looking under the five logs :D ;D

Thanks for coming over and giving me some advice
Always willing to help - Allan

Thank You Sponsors!