1. Welcome Hearth.com Guests and Visitors - Please enjoy our forums!
    Hearth.com GOLD Sponsors who help bring the site content to you:
    Hearthstone Soapstone and Cast-Iron stoves( Wood, Gas or Pellet Stoves and Inserts)
    Caluwe - Passion for Fire and Water ( Pellet and Wood Hydronic and Space Heating)

Chain Speed on Different Bars

Post in 'The Gear' started by firecracker_77, Aug 25, 2013.

  1. firecracker_77

    firecracker_77 Minister of Fire

    Joined:
    Dec 16, 2010
    Messages:
    1,438
    Loc:
    NWI office - 2 Heritages; Chicago home - Woodstock
    So...this may be an obvious thought, but if my saw sprocket rotates at X rpm and I change the bar size downwards, the shorter chain makes a full revolution in less time. So if you dropped a bar size from 32 down to 16 inches, the chain is traveling at double the rpm? If that's the case, I'm getting a super short bar for my 441 and the thing will rip and tear.

    Helpful Sponsor Ads!





  2. TreePointer

    TreePointer Minister of Fire

    Joined:
    Sep 22, 2010
    Messages:
    2,035
    Loc:
    Western PA
    Assumptions:for this discussion:
    1. Both bars have the same diameter tip sprocket.
    2. Both bars are run with no load (not in wood).

    The linear chain speed is constant. The rotation speed of the sprockets is constant. Both of these are determined by the speed of the drive sprocket, which is determined by engine rpm. The drive sprocket has enough power to make the difference in chain mass and friction negligible.

    Analogy:

    You travel at 65 mph on a mile track and a half mile track. For a given time interval, you will travel around the shorter track twice as many times as the mile track. Your wheels will not rotate faster on the shorter track.
    Joful, Bigg_Redd, clemsonfor and 3 others like this.
  3. StihlHead

    StihlHead Guest

    Excellent analogy by TreePointer above.

    In general though, your WOT chain speed will likely increase some with the shorter bar (less drag and friction). Hence you may need to re-tune your saw when you put on a shorter bar to keep the engine from over-revving. The engine rev limit would also keep your original idea from becoming a reality (you would blow your 441 engine with 2x fast spinning loops).

    Also, there is no free lunch. Power is torque x revs, so if you get more revs, the torque drops and you will bog the saw a lot easier. The flip side is that with a shorter bar, you may have torque to spare, so swapping out to a larger rim will increase your chain speed w/o bogging. I usually use an 8 slot rim with 16-18 inch bars on my 361s, and with 18-20 inch bars on my 044. Inboard clutch saws are great for that. Try an 8 slot rim on your 441 with a 16-20 inch bar. They are pretty cheap, and more revs work well when doing some types of cutting. The power remains the same, but revs increase and torque drops. The default rim on the 441 saws is a 7 slot.
    Joful, clemsonfor and MasterMech like this.
  4. firecracker_77

    firecracker_77 Minister of Fire

    Joined:
    Dec 16, 2010
    Messages:
    1,438
    Loc:
    NWI office - 2 Heritages; Chicago home - Woodstock
    I somewhat understand. Not completely.

    On a shorter chain, a specific cutter will pass through the wood twice as often on a bar half as long so it's moving twice as quickly?
    JOHN BOY likes this.
  5. StihlHead

    StihlHead Guest

    You are stuck on your original track. It is not moving twice as quickly (or fast), but traveling half the distance.
    Jon1270 likes this.
  6. TreePointer

    TreePointer Minister of Fire

    Joined:
    Sep 22, 2010
    Messages:
    2,035
    Loc:
    Western PA
    True, one specific cutter will pass through the wood more frequently on a shorter chain (it's traveling on the shorter track). That would be one cutter doing, say, twice the work in a given time period. While each individual cutter on a long chain will have fewer passes through the wood in a given time period, there are many more cutters doing work in that longer chain.

    To put it another way, the speed (linear chain speed, ft/s) at which a single tooth passes through the wood does not change when you chain bar length. The frequency an individual tooth makes a pass through the wood does change.
    clemsonfor and bryan like this.
  7. MasterMech

    MasterMech Guest

    If you want it to rip and tear, bump the size of the sprocket up. If you've been watching the videos of my MS460 that I've put up, that saw is running a 20" bar with an 8 pin rim. It rips alright.... ::-)
    TreePointer likes this.
  8. TreePointer

    TreePointer Minister of Fire

    Joined:
    Sep 22, 2010
    Messages:
    2,035
    Loc:
    Western PA
    Bingo!

    There's your increased chain speed.
  9. JOHN BOY

    JOHN BOY Minister of Fire

    Joined:
    Sep 20, 2012
    Messages:
    532
    Loc:
    Western Mountains ,NC
    Try a 18 inch bar you'll be amazed. I agree with the statements above but also disagree to some extent that a 32 inch bar will also have more drag going throw the wood. Frankly i wouldnt run anything bigger then a 25 on the 441 , but thats just me.
  10. firecracker_77

    firecracker_77 Minister of Fire

    Joined:
    Dec 16, 2010
    Messages:
    1,438
    Loc:
    NWI office - 2 Heritages; Chicago home - Woodstock
    That's great b/c it's the bar that came with it and I have bought a spare chain. I would never go bigger than a 25". I like smaller stuff... which is why I told them to downgrade my 290 to a 16" bar when I bought that one last October.
  11. DexterDay

    DexterDay Guest

    Put an 18" and an 8 pin rim on that 441 and she will RIP!!!

    Changing to the 8 pin changes the gearing, which will increase the actual chain speed. But with a loss of torque. But by dropping 7" of bar length, you won't need as much torque. Once you step over 20", then slap the 7 pin back on...

    I like to run 20" 8 pin rim on my 460 mag... Makes me smile :) A lot.... ;)

    image.jpg
    TreePointer and JOHN BOY like this.
  12. JOHN BOY

    JOHN BOY Minister of Fire

    Joined:
    Sep 20, 2012
    Messages:
    532
    Loc:
    Western Mountains ,NC
    Thats what i run on the 044 ,and nothing stops it. A muuffler mod on the 290 will really wake that saw up...there so restricted.:(
  13. firecracker_77

    firecracker_77 Minister of Fire

    Joined:
    Dec 16, 2010
    Messages:
    1,438
    Loc:
    NWI office - 2 Heritages; Chicago home - Woodstock
    I would screw up a muffler mod. I'm not mechanical.
  14. MasterMech

    MasterMech Guest

    If you can operate a handheld drill, you can do a MM on that 290. You only have to pull the deflector cover really to get it done. The more difficult part would be re-tuning the carb but I bet a dealer would do that for you for free, seeing as how you just bought that pretty new 441C-M and stuff. ;)
    clemsonfor and TreePointer like this.
  15. Gary_602z

    Gary_602z Minister of Fire

    Joined:
    Oct 30, 2009
    Messages:
    930
    Loc:
    Lake Odessa,MI
    Come on Dexter, nobody keeps their tools hung up and runs a saw with with a worn out bar like yours!:)

    Gary
    clemsonfor and DexterDay like this.
  16. amateur cutter

    amateur cutter Minister of Fire

    Joined:
    Aug 20, 2010
    Messages:
    1,170
    Loc:
    West Michigan
    8 pin on my 046 with a 20" bar, is a really nice combo. I also run the 8 pin on the 064 at 24" with skip chain. Does well for me.
    I keep telling you guys, Dex buys His firewood, & polishes His saws for pics. Is that bench carpeted? A C
    ailanthus and DexterDay like this.
  17. shawn6596

    shawn6596 New Member

    Joined:
    Sep 7, 2013
    Messages:
    86
    I run a 670 ECHO with a 24" bar. It is my go to saw. I recently went to a skip tooth chain, and o-my. It is a monster. The oregon skip tooth was only $17. Also some how I lost the top of 2 cutters and I called the guy up and he offered to send me some replacement cutters. I love the chain so much I ordered 2 more and he threw the cutters in. It came to less than $45 for both chains and shipping. I ordered them friday and they were here today.
  18. HittinSteel

    HittinSteel Minister of Fire

    Joined:
    Aug 11, 2008
    Messages:
    1,587
    Loc:
    Northeastern Ohio
    Appears it is!....... and it's cleaner than my living room carpet :eek:
  19. MasterMech

    MasterMech Guest

    That's actually not a half-bad idea (the carpet), if you build saws for sale, cosmetic condition is everything when it comes to final value.
    clemsonfor and DexterDay like this.
  20. Jags

    Jags Moderate Moderator Staff Member

    Joined:
    Aug 2, 2006
    Messages:
    14,638
    Loc:
    Northern IL
    Another way to look at this is feet per minute traveled. With a long bar - the chain is moving at xxx ft per minute. Shortening the bar doesn't change this. Only a change in engine RPM or the Gearing (sprocket) can change this. At the same feet per minute - the chain is moving at exactly the same speed no matter how long or short the bar is (not accounting for resistance, etc.). The same amount of cutters are passing a given spot.
    Nixon and TreePointer like this.
  21. MasterMech

    MasterMech Guest


    If the chain sprocket is able to haul say, 80 inches per second (that's roughly 55 MPH ;)), then the length of the chain loop does not affect that. Doesn't matter if you have 40" of chain or 60" in the loop, it still passes a given point at the rate of 80" per second. Only altering the drive sprocket size or the engine RPM will change that rate of 80" per second.
  22. lukem

    lukem Minister of Fire

    Joined:
    Jan 12, 2010
    Messages:
    3,687
    Loc:
    Indiana
    I usually line my workbench with a big sheet of cardboard (pallet slip-sheets that I get from work) for stuff that is really messy (tear down), or needs to be really clean/prevent scratches (final assembly). I throw out the cardboard like a dirty kleenex once I'm done. A couple staples with the staple gun in two corners keeps them in place nicely.
  23. MasterMech

    MasterMech Guest

    I'm currently making do with a makeshift bench fabricated out of a damaged ping-pong table cut in half and screwed together. ;lol
  24. firecracker_77

    firecracker_77 Minister of Fire

    Joined:
    Dec 16, 2010
    Messages:
    1,438
    Loc:
    NWI office - 2 Heritages; Chicago home - Woodstock
    It makes sense now.
    MasterMech likes this.
  25. firecracker_77

    firecracker_77 Minister of Fire

    Joined:
    Dec 16, 2010
    Messages:
    1,438
    Loc:
    NWI office - 2 Heritages; Chicago home - Woodstock
    How many CC?

Share This Page