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Processor chain speed

Started by SPD748, August 25, 2014, 08:47:38 AM

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SPD748

I'm going to run a .404 chain on an 18H bar for my processor. The .77 in^3 hydraulic motor will spin around 4500 rpm at 15 gpm. With a 13 pin sprocket, the chain speed would be around 1970 fpm or 33 fps. Is this fast enough to cut efficiently?

-lee
Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

whitepine2

 I think you are a little slow as most saws run over 10K this is what I went by. You could check the RPM's on any saw and go by that,don't think you need that kind of speed but if you got the power go for it.
First saw I made went at about 10K small fast motor but did the job
until got a motor with more power worked better but never checked
the RPM, if it works don't fix it.

SPD748

Thanks WP.

The motor I'm looking at has what appears to be a 5000 rpm max speed. Theoretically this speed would be achieved at around 17-18 gpm. Would you think I could push a little more oil to the motor or do I need to look at a larger sprocket?

... or should I run it at ~33 fps and be happy :)

I read a spec sheet on a Husky chainsaw which stated the chain speed was 65 fps. That speed would require the motor to spin at 9000 rpm with a 13 pin sprocket. I'm no engineer however I really don't see this little motor staying together at that speed :o

-lee
Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

Hilltop366

I would think it all depends on the power available.

I made the mistake of trying to get chainsaw chain speed on a chainsaw mill I had built that used a 16hp b&s engine, the engine didn't have enough power to cut at that chain speed, so I changed the driven pulley to gear it down. I think where I went wrong is the .404 harvester chain comes with the rakers cut much lower than standard saw chain so the cutters take a bigger bite.

SPD748

Quote from: Hilltop366 on August 26, 2014, 09:10:14 AM
I would think it all depends on the power available.

I made the mistake of trying to get chainsaw chain speed on a chainsaw mill I had built that used a 16hp b&s engine, the engine didn't have enough power to cut at that chain speed, so I changed the driven pulley to gear it down. I think where I went wrong is the .404 harvester chain comes with the rakers cut much lower than standard saw chain so the cutters take a bigger bight.

My processor will be powered by an 85 hp John Deere diesel engine. The saw motor (Webtec/Danfoss/whoever owns the company now) is .77 in^3 in displacement which, according to the webtec site, makes 7.5 hp at 1500 psi with a 2500 psi cap. The site states that the maximum speed for the motor is 5000 rpm.

-lee
Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

Hilltop366

I can't comment on the hydraulic motor side of things just the chain from my own experience.

I think you have lots power if you can get it to the chain it should cut well.

The Oregon web site says:

Minimum
3,000 ft./min. 15 m/sec.

Recommended
8,000 ft./min. 40 m/sec.

Maximum
8,000 ft./min. 40 m/sec.


http://www.oregonproducts.com/harvester/pdf/18HX.pdf

Hilltop366

Another link that might help you out.

Both of these links point out that these are harvester chains not chainsaw chains, I see that the rakers are 0.50 for the harvester chain verses .025 to .030 for chainsaws.

http://www.oregonproducts.com/pdfs/Harvester_HandbookA106976af.pdf

SPD748

That brings up an excellent point that I haven't considered, Hilltop. I take it that the harvester chain would require more power to pull than a saw chain based on the bigger 'bite' of the harvester chain. Would I need to run a .404 / .063 gauge saw chain on a 16H bar?

-lee
Frick 0 Handset - A continuing project dedicated to my Dad.

410 Deere, 240 Massey... I really need a rough terrain forklift :)

Sawing Since 1-19-2013 @ 3:30 pm
Serving Since 2002
"Some police officers give tickets, some gave all."

Hilltop366

Yes and yes, that second link to the handbook has a lot of good info in it.

blackfoot griz

I'm running 15 gpm @ 1500 psi for the clamp, saw motor and saw cylinder and have enough power to run a .404 chain.  If you push 17-18 gpm @ 2000--2500 psi to that particular saw motor you will have no problems!  My guess with 18 gpm @ 2000 psi on a 13 or 14 tooth sprocket is that you will have a 5- 7 second cut on a 12 inch block.

My guess with your combo, you will be waiting for your splitter to return the home position--in other words the saw cycle would be quicker than the splitting cycle.

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