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Torque increase

Started by charles mann, August 04, 2022, 11:51:50 AM

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charles mann

I have a fully stock stihl 661 with a 7 tooth sprocket. Is there a way to increase the tq on it, at a reasonable cost? I need to, but dont want to, csm a blk walnut and pecan log, both are around 43" on the big end, so i need to get a 54"+ bar. 

I know more tq will result in less speed, longer cut time. But pulling that much chain through that width of cut will more than likely be above the power range of the saw, but for 2 logs, cutting 12/4 slabs, i wont have but maybe 7 or 8 slabs per log. 

Running a skip tooth might aid in reducing the load/strain on the power head, should again, increase cut time. 

I am NOT looking at CS milling wide cuts/slabs, more on the once in a blue moon type thing, but i have a request for some BWN tables and need to work on a wedding gift dining table for an acquaintance the pecan log came from. 

Thoughts/advise? 
Temple, Tx
Fire Fighting and Heavy Lift Helicopter Mech
Helicopter and Fixed Wing Pilot

doc henderson

 you can decrease the size of the drive sprocket if available.  I do the skip tooth on my 880 with a 5-foot bar.  It will pull the regular chain, but bogs easily if I apply to much pressure.  It is easy to do with dogs in the wood.  you can also alter the angle back and forth to keep the chain contacting less wood in the cut.  figure how to keep the bar and chain well oiled.  I am not a CSM guy.  I own one but have never taken it out of the bos.  or find someone with a band mill that has the capacity for the log.  keep the chain very sharp, like maybe several sharpening's per slab cut.  I would use wedges behind the bar and chain to keep the kerf from clamping down on the back side of the bar not doing the cutting.  It may help you to put the log on a slant to help with forward movement.  I think if you are pushing the limit of the saw, you should maximize all factors that take power away from the job of cutting.  I would dread this, so make it easy on the operator.  I would want a setup so you can just stand and hold the throttle and with little effort manipulate the machine.  I free hand split a 5 foot by 8-foot maple log with mine, and it went better than I planned.  I use a full skip chain.  you will have lots of chips.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

doc henderson

Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

doc henderson

Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Ianab

Quote from: charles mann on August 04, 2022, 11:51:50 AMRunning a skip tooth might aid in reducing the load/strain on the power head, should again, increase cut time.


It won't necessarily increase the cut time. Having 1/2 the number of cutters each taking a decent bite can be faster than a full comp chain that's only scraping dust (because you don't have enough power to keep that many working). 

Any saw / chain / wood combo would have a sweet spot where each cutter is working properly, and the saw still has enough power to drive them. Exactly what that number is will depend on "things". But whatever that number happens to be, if you exceed it with a longer bar, cutting speed quickly drops off. 
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

lxskllr

I'd just try, and see what happens. I've milled oak with a 661 and ~32"(36" bar) completely buried where I was chopping off bark/knots so the mill would pass, and it wasn't struggling at all. I'm thinking it'll be /ok/ with a skip chain. Not great, but good enough for a one-off project.

charles mann

Quote from: lxskllr on August 05, 2022, 06:04:15 AM
I'd just try, and see what happens. I've milled oak with a 661 and ~32"(36" bar) completely buried where I was chopping off bark/knots so the mill would pass, and it wasn't struggling at all. I'm thinking it'll be /ok/ with a skip chain. Not great, but good enough for a one-off project.
I was planning on trying it, but wanted to see what folks would recommend on increasing the tq. I researched the forum via a google search and there were several topics about this subject but all were on smaller saws. I came across a youtube vid of a guy trying 5 different muffler styles and using a new chain each time, it seems a gutted 3 ported muffler (2 ports on the side and 1 on top) was the best overall in cut time and cooler temps. So that may be an option, if i can source a 3 port muffler, but his looked kinda homemade, which im not deterred by that and can do the welding. 
I dont have an issue pulling a 36" bar and full teeth ripping chain, but im going to a bigger bar and more teeth, so i figured the added drag of the bar length and links, plus 6+" of somewhat 3-4 yr old downed and dry/seasoned hardwoods might put a bit more strain. But like you and i said, a 1 off job here a d there shouldnt hurt it. 
@doc henderson 
Iv done quite a bit of CS milling, and im sure not even close to others on here. I got the 661 to replace my jonesred 2166 and very aging husq 372 and cut max width of my 36" milling rails with no issues, other than sharpening after each cut, which isnt an issue, just a time consuming process. An 880 is much larger and more powerful saw than a 661, and i shoulda got the 880, but $2000 vs. $1400 is big chunk of pennies and wagging an 880 around the woods and up a tree, thanks, but no. 
Temple, Tx
Fire Fighting and Heavy Lift Helicopter Mech
Helicopter and Fixed Wing Pilot

charles mann

@doc henderson i reread my comment to you. The last part "thanks, but no" wasnt a hard no to anything you mentioned, just my old tail aint wagging that much saw around and def not free climbing a felled tree, looking like a gorilla in the tops, trying to handle that much saw. Def not now that i found out how bad off my back is. Iv never been shown and explained how broke it was. Iv gotta have 4 spinal ears broke/cut, fuzed back the vertebrates, goota get 2 disks replaced, and gotta get pins and screws to keep thing in alignment. Been dealing with it for 12 yrs and didnt know the extent of the damage till a few weeks ago. Gotta take it easy from here on out, esp for a few months, maybe yrs, after surgery. 
Temple, Tx
Fire Fighting and Heavy Lift Helicopter Mech
Helicopter and Fixed Wing Pilot

doc henderson

It is hefty, I think over 50 pounds with fuel and that bar.  I carry it to my mill area, or to the truck and no farther than needed.  It is not bad with a half scabbard and the bar behind, but a hand on the handle and the other way behind under the bar scabbard.  the weight of the saw is all you need in the cut, so in a way, I try to relax and just keep control of the direction, but no need to crank on the dogs, if the chain is sharp.  I know you are a mechanical guy, so it was my honor to throw out a few ideas to forward the conversation and try to provoke some ideas.  I took it as a no thanks to 50 pounds of saw.   :D thanks Charles.
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

doc henderson

you may recall I got the 661 and had troubles with it, so the dealer gave me full credit towards the 880.  
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

charles mann

Quote from: doc henderson on August 06, 2022, 03:28:25 AM
you may recall I got the 661 and had troubles with it, so the dealer gave me full credit towards the 880.  
Guess i need to start complaining then. But mine is 6 yrs old and purchased it on the valentines day special the stihl dealer was having. A 661 with a 36" bar and chain, with my ag tax card, cost $999 after the stihl discount. 
Temple, Tx
Fire Fighting and Heavy Lift Helicopter Mech
Helicopter and Fixed Wing Pilot

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