Chain HP Limits

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bacon K5

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Does anyone know of a reference for hp ratings for different saw chains? I have a homemade bandsaw Mill that works ok, but I'm thinking of converting to a large scale chainsaw Mill using a 36-42" bar and a forestry harvester sprocket drive. Obviously I want to keep the chain thin to minimize material removed, but I don't want to get something weak either. I'd like to run 20-25hp on this and I assume a harvester uses much more than that, but I want to have the data to support it. Thanks.
 
Does anyone know of a reference for hp ratings for different saw chains? . . . I'd like to run 20-25hp on this and I assume a harvester uses much more than that, but I want to have the data to support it.

Call Oregon Customer Service. They do a lot of technical harvester support:

We're here to help, call 1-800-223-5168, Monday through Friday 6:30 AM - 4:00 PM PST. For questions about your order, please contact an Oregon Products Customer Support Representative at 1-800-223-5168.

Philbert
 
Lucas slabbers run fairly powerful motors
eg
The Lucas Super Slabber is powered by an 23HP Briggs and Stratton, Vanguard engine and is capable of cutting up to 2.7m (9’) wide and a depth of 271mm (10.5”).
Lucas also has a 30HP mill that runs a slabber
They use standard 404 chain.

The load back on the engine is limited by the raker depth used.
I've heard of users dropping the rakers significantly and while it cuts fast (but no faster than a BS) the finish is RABB - rough as a bears behind.
You will get a MUCH better finish with a BS.

In fact, seeing as you plan to only run a 36-42" bar which reduces to a 30-36" cut, I don't see why you are wasting your time with chains and go straight for BS setup.
It would be a different thing if you were needing to cut 50+"
 
Like I said in my original post, I already have a BS setup but I cut a lot of hard white oak that is 30+ wide and my homemade BS setup has reached it's limitations. I run into wavy cuts and have no way to sharpen my own blades. Rather than invest in improving my BS I want to use the bits and pieces I have laying around to make a slabber.

So far I've been unsuccessful getting any useful information from stihl, Oregon, or Carlton for ratings on handheld chains. Liability reasons I'm sure. Oregon does make 16H .063 chain that is rated for high power, but finding a durable bar/sprocket combination that I like isn't as easy.
 
Lots of good stuff in there, but I don't see any HP ratings. Did I miss it?
 
Rated by motor displacement; you will have to estimate horsepower based on that.

Check out 50 cc saws, for example, and see what typical horsepower ratings are for them.

Did you call Oregon's 800 number re: harvester chains?

Philbert
 
So far I've been unsuccessful getting any useful information from stihl, Oregon, or Carlton for ratings on handheld chains. Liability reasons I'm sure. Oregon does make 16H .063 chain that is rated for high power, but finding a durable bar/sprocket combination that I like isn't as easy.

Maybe because up to a point the applied power is not that relevant.
What matters more is the back load on the chain and how the chain is set up.

If a sharp pico chain is set up with 0.005" rakers the back load on the chain will be 5/8ths of bugger all so this could be spun with a 100HP motor.
It will make a lot of fine dust and cut very slowly. With a powerful powerhead the tendency will be to then push it too hard especially as the chain gets blunt so it will overheat then stretch and then come off the bar. Breakages are also more likely.Long term it will overheat stretch and break.

If the same chain is set with 0.025" rakers it should cut fine whether a 5 or 50HP power head is used provided the chain is kept sharp at all times and it is not pushed when blunt it should be OK.

If the rakers are dropped even more on the same chain - now you can prepare for chain breakage.

Like I said above, Lucas slabbers run 60"+ bars with 30HP power heads run 404 chain without any problems.
What else do you need to know?
 
What else do you need to know?

A lot actually. Everything you said is true, kind of, but a chain or any mechanical member can withstand a certain amount of tensile stress. That stress can be back calculated into a torque based on sprocket diameter and engine speed which relates directly to HP. Raker depth, skip vs full tooth, sharp vs dull, and force on the cutting are bar are all variables and valid inputs, but if those are all you use to size a system it will be dangerous at best. You'd be sizing via Russian roulette and just waiting for a break. If done properly a break should only happen due to neglect, excessive wear, or some accidental impulse.

The above is exactly why the chain mfgs are reluctant to give the info out - too many variables that most people don't consider.

I've found the 18HX chain is properly rated for the hp range I want and while it's .080" vs .063" the kerf is only .020" wider. Being able to sharpen my own cutting tools and knowing everything is up to the task far offsets the extra wood I'll take out in my opinion. I'll run a 12t sprocket on a 1" shaft with dual belts, PTO clutch, on a 25hp engine. In the future if I run into another cheap engine I can add a secondary and still have margin on the chain.
 
The above is exactly why the chain mfgs are reluctant to give the info out - too many variables that most people don't consider..

And I'd say they don't provide the info because its meaningless. If they provided it and some ningnong decided to use the max HP motor but with the worst possible chain setup and the chain broke then they may be held liable. It's the same reason car manufacturers don't provide info on the maximum HP motor that can be put in a motor vehicle.
 
A lot actually. Everything you said is true, kind of, but a chain or any mechanical member can withstand a certain amount of tensile stress. That stress can be back calculated into a torque based on sprocket diameter and engine speed which relates directly to HP. Raker depth, skip vs full tooth, sharp vs dull, and force on the cutting are bar are all variables and valid inputs, but if those are all you use to size a system it will be dangerous at best. You'd be sizing via Russian roulette and just waiting for a break. If done properly a break should only happen due to neglect, excessive wear, or some accidental impulse.

The above is exactly why the chain mfgs are reluctant to give the info out - too many variables that most people don't consider.

I've found the 18HX chain is properly rated for the hp range I want and while it's .080" vs .063" the kerf is only .020" wider. Being able to sharpen my own cutting tools and knowing everything is up to the task far offsets the extra wood I'll take out in my opinion. I'll run a 12t sprocket on a 1" shaft with dual belts, PTO clutch, on a 25hp engine. In the future if I run into another cheap engine I can add a secondary and still have margin on the chain.
Bob has been doing this for a long time, he is very smart and not kissing ass here but if you were to check out his postings you would probably see that he’s got **** figured out.
Imo I think raker height has everything to do with how much load a chain can take, and saying this now I am realizing that the type of wood you cut is an added variable.

You want a fixed variable to figure this out, I understand that. If you really want that take three different types of chains and put some weight on them. I’m gonna guess that they will all hold at least 60lbs probably more.
But that doesn’t really tell you anything, it’s the cutting conditions, the wood the raker depth, the chain speed, the heat that fatigues the metal, the sharpness of the tooth, the weight of the chain itself (inertial force on chain via the tooth) the speed of the saw (how many teeth are on the rim)that tells us when a chain fails.
These are way too many variables to consider and thus you can’t just say 3/8 chain supports this kind of HP.
So...

If bob says from experience that picco chain holds up with a smaller raker height better than a higher one with a 30hp was what does that tell you? It tells you from his experience that these chains are tough, and it’s really not a dangerous situation to run smaller chain on a big saw.

Imo after extended use employing physical checks is your safety margin. How many times did you have to re tension your chain? If you’ve had to re tighten your chain more than 4 times you should start checking for rivet slack. When that happens a chain is now stretching its ties farther than designed and it’s on the verge of snapping.
With proper sharpening and raker depth imo the cutting tooth will be gone before this actually happens with today’s chains!
 
These are way too many variables to consider and thus you can’t just say 3/8 chain supports this kind of HP.

No offense, but this is literally the most incorrect statement I have ever read on a forum. I'm a mechanical engineer and these kind of calculations are what I do for a living. I'm not arguing anyones experiences or stories, but just because you ran a 30hp engine on a 3/8 chain does not mean you USED 30hp (because of all the variables weve discussed). Id prefer to size everything so that if I do end up using the full power of the engine, it wont cause issues.

HP is a load at a speed - it DIRECTLY ties back to a tensile load which a chain is rated for. Consider a log chain (the kind you find in a tractor). Would you say the load it can carry depends on what kind of wood youre towing or what kind of ground it's dragging on? No. The chain gets rated for a load and all those factors determine how much of that rated load you actually use.

I know arguing on a forum is like peeing in the wind, but with all due respect, this is a subject I am confident in and your liberal use of "imo" and some of the incorrect statements ive seen are quite honestly scaring me. I'm only responding to try to educate and help prevent injury. Please dont take this as chest pounding.


If anyone cares, heres some reference material to keep you safe if using high power. This same information exists somewhere for .063 and smaller chain and thats what I was looking for but have not found. I know it's "worked" for some, but thats not what I was asking for - I want the actual data.

Check out page 22 for all technical data on 11, 16, and 18 harvester chain
http://en.oregonproducts.com/pdfs/Harvester_HandbookA106976af.pdf

Check page 7 for Stihls equivalent.
https://m.stihlusa.com/WebContent/C...nManuals/STIHL_Harvester_Saw_Chain_Manual.pdf
 
No offense, but this is literally the most incorrect statement I have ever read on a forum. I'm a mechanical engineer and these kind of calculations are what I do for a living. I'm not arguing anyones experiences or stories, but just because you ran a 30hp engine on a 3/8 chain does not mean you USED 30hp (because of all the variables weve discussed). Id prefer to size everything so that if I do end up using the full power of the engine, it wont cause issues.

HP is a load at a speed - it DIRECTLY ties back to a tensile load which a chain is rated for. Consider a log chain (the kind you find in a tractor). Would you say the load it can carry depends on what kind of wood youre towing or what kind of ground it's dragging on? No. The chain gets rated for a load and all those factors determine how much of that rated load you actually use.

I know arguing on a forum is like peeing in the wind, but with all due respect, this is a subject I am confident in and your liberal use of "imo" and some of the incorrect statements ive seen are quite honestly scaring me. I'm only responding to try to educate and help prevent injury. Please dont take this as chest pounding.


If anyone cares, heres some reference material to keep you safe if using high power. This same information exists somewhere for .063 and smaller chain and thats what I was looking for but have not found. I know it's "worked" for some, but thats not what I was asking for - I want the actual data.

Check out page 22 for all technical data on 11, 16, and 18 harvester chain
http://en.oregonproducts.com/pdfs/Harvester_HandbookA106976af.pdf

Check page 7 for Stihls equivalent.
https://m.stihlusa.com/WebContent/C...nManuals/STIHL_Harvester_Saw_Chain_Manual.pdf

So rather than learn how to sharpen your bandsaw blades, or just finding a good business to sharpen them for you, you want to go to the trouble of rebuilding your saw for chain? Call the MFGR, if they have the data and their team of lawyers are comfortable with it being released, I'm sure they'll send it to you.

If you were dealing with primarily yard trees, I could maybe understand wanting to use chains but it sure seems odd to give up the thin kerf and known power requirements of a BS mill in pursuit of a wide slabbing CSM. Maybe you just want the challenge and want to jump from BS -> CSM but why not expend the same effort into fixing your BS mill to reduce the wavy cut? Tensioning device or wheel heft or any number of things could be the culprit. If you plan on cutting more than just a few trees, that is a lot of money turned to dust.

Being an engineer, it seems like you're divorcing yourself of one problem to move to a bunch of new ones. The devil you know is better than the devil you don't. But if you just want the challenge, good luck. I hope you'll post pics/info as you continue.
 
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