Chain for firewood processor

[polemidis]

Hello all, Its my 1st post here, my apologies if it would be created in another category.
I have designed an Firewood processor and I am missing a few details. I am stuck on the chainsaw size and on the availability of chainsaw bars.

Because my gas motor is not so strong I would like to stick with a 3/8" chain, but I cannot find a 3/8" bar wide enough to accept a sprocket with 3.35"-3.5" diameter (15Teeth). The sprocket is mounted on the hydraulic motor and will rotate at around 4700rpms at 1800psi.

All the harvester bars I found online are 0.404. Do you think I should go to that pitch, or is there any other way that I haven;t thought?
The regular stock bars are to narrow and the chain will not sit in the channel with such a big sprocket.

If the .404 chain is the way to go, do you know how much more power they demand compared to a 3/8"?
The hydraulic motor will develop 4700rpms at 166in-lb torque so a 3/8" chain with a 15T sprocket will move at 4400ft/min linear speed, while with a 0.404 the chain will rotate at 4800ft/min
Are that speeds adequate? Should I put a 14T sprocket with a 0.404 to maintain 4500ft/min and have more torque?

Sorry too many quastions but I do not have experience with that particular matter and I do not know what works best. I understand that the 0.404 is a safer chain. I just do not know if I have enough hp.

Thank you in advance!!!!

 

[ChoppyChoppy]

You need to run 4o4 .080 gauge if you want it to last. chainsaw bars and chains are too light duty for processor use. Yes, I know some small processors use them, and they also go through bars quickly.

Plus 404 is cheaper than 3/8" chain.

 

[rd35]

I'd just buy a longer solid bar,reshape the end at the drive sprocket so that it will fit, and cut a new bar stud slot for mounting it. Not sure how your design is set up but that's what comes to mind as I read your post.

 

[muddstopper]

Hello all, Its my 1st post here, my apologies if it would be created in another category.
I have designed an Firewood processor and I am missing a few details. I am stuck on the chainsaw size and on the availability of chainsaw bars.

Because my gas motor is not so strong I would like to stick with a 3/8" chain, but I cannot find a 3/8" bar wide enough to accept a sprocket with 3.35"-3.5" diameter (15Teeth). The sprocket is mounted on the hydraulic motor and will rotate at around 4700rpms at 1800psi.

All the harvester bars I found online are 0.404. Do you think I should go to that pitch, or is there any other way that I haven;t thought?
The regular stock bars are to narrow and the chain will not sit in the channel with such a big sprocket.

If the .404 chain is the way to go, do you know how much more power they demand compared to a 3/8"?
The hydraulic motor will develop 4700rpms at 166in-lb torque so a 3/8" chain with a 15T sprocket will move at 4400ft/min linear speed, while with a 0.404 the chain will rotate at 4800ft/min
Are that speeds adequate? Should I put a 14T sprocket with a 0.404 to maintain 4500ft/min and have more torque?

Sorry too many quastions but I do not have experience with that particular matter and I do not know what works best. I understand that the 0.404 is a safer chain. I just do not know if I have enough hp.

Thank you in advance!!!!

I think you got your math a little wrong. (rounding?) Here is the formula for figureing chain speed.
Take the chain pitch and multiply by 2. Multiply the above number by the number of teeth of the saw sprocket.
Multiply that number by the saw R.P.M.

The final answer will be the chain speed in inches per minute, just divide by 12 to convert to feet per minute.
Your .404x2x15x4700rpms =56964 inmin. Divide that by 12= 4774ftmin. I am guessing you just rounded the number up to 4800ftmin

Now the question is to whether your hyd motor will pull the chain. I will just add a comparison I made using a 3120 chainsaw. 9000rpms, chain speed, 65.9fts. 8.5hp and 7.7nm torque. The 7.7nm converts to 68.150742595inlbs. first thing too look at is chain speed, I dont know sprocket size on a 3120 chainsaw, but for this comparison it doesnt matter, we are measureing chain speed, not engine rpms. Your 4774 ftmin converts to 79.11ftsec, so your chainspeed is about 1.6 times faster than a standard 3120 chainsaw. Now the question becomes will the motor have enough power to pull the 404 chain. Chainsaw torque is 68 inlbs, your hyd motor you claim 166inlbs. So first glance would suggest you have about 2.4 times more power to pull the .404 chain than the 3120 chainsaw. Next you will need to look at the hp your hyd motor produces, 166inlb=9.6ft lbs. 9.6ftlbs x 4700rpms =8.7hp. The 3120 gas chainsaw is only 8.5hp so you are 2tenths more hp with your hydraulic motor. Assuming the hyd numbers you posted are correct, then you should be able to pull the .404 chain at least as well as a 3120 husquvarna chainsaw.

This is still not a accurate comparison. Torque numbers are rated at the shaft of the motor or engine. Going with a larger sprocket will reduce the torque number. The bigger the dia of the sprocket the lower amount of torque. Going from a 7 or 8 tooth sprocket to a 15 tooth I would estimate about a 50% reduction in torque. Your suggested torque numbers are over twice the numbers for the 3120 chainsaw. There are formulas available to get the exact number, but I dont know the dia of a standard sprocket or the dia of the 15 tooth sprocket so I cant do the math. With a hyd motor, you do have the option of increaseing the hyd psi to increase available torque, as long as you have the engine hp to pull the hyd's.

What cuin size and type hyd motor are you using an rated oil flow.

 

[polemidis]

Thank you everybody! Mudstopper yes, my numbers are rounded man! Noone wants to hear the small details especially when they are going to be wrong 100% Losses in pressure through all the valves, losses in flow etc
Thank you very very much for your analysis! Everything you said sounds correct, except the hp, it doesnot look right! Starting with a 16hp gas engine, putting only 8.5hp in the chain seems too little! Anyway, it does not make sense to investigate more.
I leaning towards the Parker 0.58in³ that will get 12gpm with a maximum pressure 1800psi. Am I right that you do not like the Parker? Nice to meet you in that forums too my friend!

So, thank you guys. I am confident that it will work. In addition I will have a hydraulic circuit with some "intelligence" so hopefully everything will work fine! It will read the pressure the saw motor develops and before it goes too high and stall, it will gently stop pushing the motor into the wood. I will keep you posted about the results!

 

[Bobby Kirbos]

Thank you everybody! Mudstopper yes, my numbers are rounded man! Noone wants to hear the small details especially when they are going to be wrong 100% Losses in pressure through all the valves, losses in flow etc
Thank you very very much for your analysis! Everything you said sounds correct, except the hp, it doesnot look right! Starting with a 16hp gas engine, putting only 8.5hp in the chain seems too little! Anyway, it does not make sense to investigate more.
I leaning towards the Parker 0.58in³ that will get 12gpm with a maximum pressure 1800psi. Am I right that you do not like the Parker? Nice to meet you in that forums too my friend!

So, thank you guys. I am confident that it will work. In addition I will have a hydraulic circuit with some "intelligence" so hopefully everything will work fine! It will read the pressure the saw motor develops and before it goes too high and stall, it will gently stop pushing the motor into the wood. I will keep you posted about the results!

Are you using an Arduino or Raspberry Pi for the "intelligence", or a mechanical solution?

 

[Huskybill]

Are you putting flow control valves on the hydraulic feed and chain speed?

 

[polemidis]

Are you using an Arduino or Raspberry Pi for the "intelligence", or a mechanical solution?

Are you putting flow control valves on the hydraulic feed and chain speed?

Hydraulics. Here is the diagram. The only valve in question is the "LRBC" modulating valve, maybe I need a pressure relief valve with remote instead. I am currently working with Sun's distributor to figure the correct one.

"Oil-Feed" is the input from Port A of the Directional Valve, "Oil-Rtrc" is the Port B.
Anything with "GAU" is a pressure gauge, the saw motor return goes to the tank since there is no need for reverse.
"Feed-Ext-Cyl" is the cylinder that pushes the chainbar into the wood. Anything with "rtrc" is the retract.
The cartridge names are the identifiers in Sun Hydraulics webpage (just remove the numbers if you want to look them up)

In short that this circuit is doing (hopefully!!!! ) is:
After the oil enters from the "Oil-Feed" port, Tees before the sequense valve (SCCA) and extends the Clamp. Then the sequence opens and Tees into 2 paths:
a)Downwards to the Feed Cylinder through an flow valve (11-FCCB) permitting 1gpm
b) Towards the Saw Motor through the "FXDA" flow valve allowing 12gpm
Both the above valves are adjustable, and I will be able to tune the speed so I can cut fast but not stall the saw.

For fine tuning, or for knots, dry hardwood etc I have this extra "intelligence" where the "LRBC" valve is (maybe I will replace it with another cartridge, this one may not be the correct one)
I am sensing the pressure of the saw (dotted lines, this is the remote pilot), and when it reaches a high enough pressure (I will have to fine tune that) it opens the Feed Cylinder and backfeeds it towards the tank. The "CXBA-100" check valve(I will replace it with the CXDA) will keep backpressure of 150psi to smooth things out before it drains to the tank (through the return at the directional valve).

The 12-FCCB is to adjust the retracting speed of the feed cylinder/clamp. Maybe I do not need it- its too much?

The idea is not mine, I got it from 6kproducts, and even though they do not provide the circuit, they deserve some credit. If this manifold works, you can copy it guys, its Open Source for non-commercial use. Same thing with the firewood processor, I have developed the CAD plans, and I am correcting them as I fabricate it. Feel free to copy them, its here. The "0-Master-CAD.fcstd" file in the hardware folder. It needs Freecad to open. Its in active development, so no Bill of Materials yet, neither detailed steps on how to replicate it.
Here are some pictures:
What is missing is the most important part, I know!!! No Saw Cutting yet, I am waiting to define the bar, get the diameter of the sprocket etc.. The CAD has the main idea, I just need some details before I cut the pieces on the CNC plasma cutter

 

[Little Al]

If your processor motor is strong to do the required job you will as said in #2 post a 404x 80 gauge chain first signs of hang up /jamming =result broken chain Our boss had a small processer built for cramped spases it ran a 3/8 x063 chain never knew a chain last longer than a couple of hrs It's been stood unused in the back of the shop for to my knowledge the last 6 years keeps getting hyd bits acquired for other purposes

 

[polemidis]

If your processor motor is strong to do the required job you will as said in #2 post a 404x 80 gauge chain first signs of hang up /jamming =result broken chain Our boss had a small processer built for cramped spases it ran a 3/8 x063 chain never knew a chain last longer than a couple of hrs It's been stood unused in the back of the shop for to my knowledge the last 6 years keeps getting hyd bits acquired for other purposes

If I understood well you mean that if the chain stalls the motor, the chain will be broken soon?
If thats true then the hydraulic circuit above that detects the pressure on the saw motor is even more important that I thought! Once tuned it will never stall

 

[Marshy]

@polemidis, you should do an internet search for "harvester" or "processor" chainsaw bars. Idk what length you are looking for but here is a GB bar in 0.404 pitch that is 20" long. The heal on the processor bars are very wide.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/p/2055772185?iid=231916550522

Here is a 32" Windsor sprocket nose bar but unknown pitch.
https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/182271666708

 

[Little Al]

If I understood well you mean that if the chain stalls the motor, the chain will be broken soon?
If thats true then the hydraulic circuit above that detects the pressure on the saw motor is even more important that I thought! Once tuned it will never stall

No hitting a knot or getting nipped /twisted I was refering to the chain taking a shock& suffering breakage due to being to light/flimsy& breakage occurred even though the relief valve operated may be your set up is different but I would try to stick with the 404 chain

 

[muddstopper]

Thank you everybody! Mudstopper yes, my numbers are rounded man! Noone wants to hear the small details especially when they are going to be wrong 100% Losses in pressure through all the valves, losses in flow etc
Thank you very very much for your analysis! Everything you said sounds correct, except the hp, it doesnot look right! Starting with a 16hp gas engine, putting only 8.5hp in the chain seems too little! Anyway, it does not make sense to investigate more.
I leaning towards the Parker 0.58in³ that will get 12gpm with a maximum pressure 1800psi. Am I right that you do not like the Parker? Nice to meet you in that forums too my friend!

So, thank you guys. I am confident that it will work. In addition I will have a hydraulic circuit with some "intelligence" so hopefully everything will work fine! It will read the pressure the saw motor develops and before it goes too high and stall, it will gently stop pushing the motor into the wood. I will keep you posted about the results!

The formula for converting torque to hp is HP = Torque x RPM ÷ 5252.(9.76x4700)/5252=8.59 hp.
Before reading to much into that 8.59hp number and the comparision I made to a 3120 chainsaw. You might want to review this link about measureing hp and torque and the relatonship to force. https://www.yourmechanic.com/articl...que-twisting-power-of-your-car-by-tim-charlet.
While the comparison I made is accurate it is also misleading. This is because you are increaseing the size of the sprocket as well as the pitch of the chain. The actual force being applied to your saw chain is probably half of what the 3120 chainsaw is producing. You mention me not being a fan of Parker. That is not true, I am a very big fan of Parker and Eaton products, I just believe your choice of a .58cuin hyd motor is going to disappoint. Once you mentioned that other forum, I remembered your post on this subject there. I dont have all the numbers one needs to do all the math, but I do know of several folks that have used that very same motor for their processor builds and every single one of them used 3/8 chain and all of them complained of a slow cutting speed and bogging in the cut. Some ended up swapping that motor for the larger .75cuin motor. Will your .58cuin motor work, yes, but again I think you will be disappointed in the performance. More so if always sawing large dia wood. With that small motor, I dont think I would even consider the .404 size chain, at least not until I did the math needed to determine the actual force it will produce. Maybe KevinJ will step in and help do the math.

 

[muddstopper]

Its raining here so I sat down and done a little math.
Since I didnt know the dia of a 7th or 15th sprocket. I took the pitch of chain and multiplied by the number of teeth to come up with some numbers. A 3/8 pitch chain with 7 teeth should have a circumference of 2.625inches. A 3/8x15 tooth sprocket would be 5.625in. and a .404x15tooth would be 6.06in. Torque is a measure of force applied to a radius of a center point. In this case the shaft of the hyd motor used to turn the sprockets. You can apply 100lbs of force/torque to a outer rim of a sprocket and if it that force isnt great enough to turn that sprocket, you havent done any work. The sprocket has to move in order for the chain to cut. Using the 4700rpm numbers posted for the hyd motor speed, it As you increase the circumference of the sprocket the more force it is going to take to move it, but if you only have 100lbs of force to apply the force is not going to change. This is what happens to the force of the hyd motor, it is only capable of exerting so much force, yet we are increaseing the size of the sprocket. This means it will take more power to move the chain than is being provided. Since the hp and torque are all the motor can make, you will see a reduced amount of work (chain speed) that can be done. To gets the same amount of work from a larger dia sprocket, you would have to increase the amount of power the hyd motor can make. Going from a 3/8x7 tooth sprocket to a 3/8x15 tooth sprocket would require a power increase by a factor of 2.14x and going to a .404x15 tooth sprocket would require a 2.30x increase power factor. So while on paper, it would seem the little .58cuin hyd motor might work, it isnt going to compare to the performance of the 3120 chainsaw and would only cut at about half or less than half the speed of the gas chainsaw. Anyways, that is the best way I can explain it, probably some engineers here that can explain it a whole lot better than me.

 

[polemidis]

Muddstopper I do not recall exactly your other post man, I just remember your objection on the 0.58 parker, and when I was doing the math I end up that I need the 0.58! I recall you proposed some other type of motor (bent axis) but not exactly hat. Plz let me know what you believe is best. I havenot bought the motor yet. Only the pump and I am getting 12gpm at 1800psi max for the saw motor.
I would like to stick with what most people propose on the 0.404 chain.
The 0.58 motor with the 0.404 and a 14T sprocket gives me 4425ft/min and 166in.lbs
The 0.75 motor with the 0.404 and a 14T sprocket gives me 3422ft/min and 215in.lbs
The 14T sporocket is 3.29" OD btw.
Do you think I need more torque and less speed? One is going to be in the expense of the other

 

[polemidis]

Other than the motor discussion which is still ongoing, thank you all for your comments. I decided to go with the 0.404 it is heavier duty/stronger, allows me to use harverster bars, and because I can choose one that will fit exactly with my sprocket wide sprocket.
Thank you!

 

[muddstopper]

Muddstopper I do not recall exactly your other post man, I just remember your objection on the 0.58 parker, and when I was doing the math I end up that I need the 0.58! I recall you proposed some other type of motor (bent axis) but not exactly hat. Plz let me know what you believe is best. I havenot bought the motor yet. Only the pump and I am getting 12gpm at 1800psi max for the saw motor.
I would like to stick with what most people propose on the 0.404 chain.
The 0.58 motor with the 0.404 and a 14T sprocket gives me 4425ft/min and 166in.lbs
The 0.75 motor with the 0.404 and a 14T sprocket gives me 3422ft/min and 215in.lbs
The 14T sporocket is 3.29" OD btw.
Do you think I need more torque and less speed? One is going to be in the expense of the other

I think your 12gpm at 1800psi is going to be your achilles heel. With your 16hp motor you can bump the pressure up to about 2000psi or your oil flow by about 1gpm, but that is not going to help you much. You could go with a bigger engine and add more pressure to increase cutting power, but not sure that little hyd motor can take it. You might also consider going with a larger cuin standard gear motor, and over flow the oil a little to get the rpms you desire. The larger motor will give you more power at the same psi, and by over flowing the oil, you can get the rpms you need. I also wouldnt give up on the ideal of using 3/8 chain. I believe they are rated for up to 50hp, but dont quote me on that. I have looked at a few of the small homeowner type processors. From what I can tell, most of the manufacturers are using standard gear motors and they are over flowing the oil to get chains speed.

The numbers I gave for the 15th sprocket are for its pitch x tooth count. For a 14tooth sprocket the numbers would be 5.56. You should be able to use that number to compare against the 3/8x 7tooth sprocket which is standard on the 3120 chainsaw.

The hyd motor I suggested was this one, https://www.poclain-hydraulics.com/en/products/motors/m-mv/m1. It is a high speed axial piston motor. You can see the torque numbers are 4641lbft, Thats at 1000psi.. Up to 34hp but at a price as it those numbers are rated at 4641psi and around 18gpm. $$$$$'s. I have been told by a factory rep that I can bump the speed up to around 4500 rpms by increaseing oil flow, as long as I am not maxing out the pressure. A bent axis motor is commonly used on harvesters. These motors are usually a smaller cuin size, such as your .58cuin motor, but they also require around 5000psi to make any power.. The bent axis is expensive and so are the pump/engines to pull them. I have a new Rexroth bent axis I believe is rated for 9000rpms and 5000psi, and 2 of the proclain motors. I have one proclain motor mounted to a 27in harvester bar with .404 chain and 14th sprocket, but have never hooked hyd to it to see how it performs. This set up is over kill for most processors.

 

[polemidis]

Mudd, I just realized what is the 3120 chainsaw that you used for comparison! Thats a monster! Yes, the 0.58motor is close to its limits, 0.5gpm more to reach its maximum rpms, but it could take up to 2500psi, so in case of and upgrade to the gas engine I will can just increase the relief values without touching anything else.
Now on what you say is my achilles heel of the 16hp gas engine, it is that we just have different standards!. For me, anything similar to the 359 saw that I currently have is satisfactory! I mean, the past years I was processing firewood manually with a log splitter. The addition of the processor alone will cut 3 labor hours per cord + the savings on my back! For my setup, it is perfect, and the cost of about $4000 in equipment for the processor its good return on investment!!
The 16hp motor is cheap and available to everyone. I could go with a 30hp diesel and have all the power of the world, but the motor itself will cost $4000 instead of $300.

While I spent 200+ hours in development of the machine in research and CAD, it feels great that I will keep the plans open for anyone to build that machine. Its my return to the society, (and to all of you that helped me in the forums). So time well spent

Thank you everyoby, I think I have all the answers I needed to continue.

Feel free to ask anything you want about the processor. The link to the CAD files is https://gitlab.com/go_commons/firewood-processor but it is still under development.

 

[muddstopper]

My point of using the 3120 chainsaw for the comparison was because of your desire to use a .404 chain. With that in mind, you can put a .404 chain on a lot of smaller saws than the 3120, that doesnt mean a smaller saw would pull the .404 chain very well. As to the 359 chainsaw, its rated at 3.9 hp. I dont think you would want to try running a .404 size chain on that saw. Compareing hp numbers between the two saw sizes the 3120 saw has 2.13 times the hp as the 359. the change in sprocket size between a 3/8 7tooth sprocket and a 15 tooth sprocket is the 15 tooth is 2.14 times larger. This almost identical to the difference in hp numbers. This suggest that your .58 cuin motor will pull a 3/8 size chain similar to a 359 chainsaw. I didnt find the torque numbers listed for the 359. Also the 359 runs a short bar 16 to 24 inch, and also .325 as well as .375 size chain. I dont believe you mentioned what lenght of bar you planned on using on your processor and not knowing anything about what species of wood you will be dealing with or what size in dia wood you process might be trying to saw. With a solid mounted bar mounted to lever up and down, you should realize you will need a longer bar to saw smaller dia wood than you would normally run on a hand held chainsaw. My suspicion is that you might endup with a saw bar closer to 24in lenght and using a 3/8 chain on a 359 compariable size saw motor would work, but not as well as running a 3/8 chain 16in bar on the same saw. As I said in my first post, the .058 hyd motor will work to power a saw chain, just not as well as other options.

From a personal perspective, I think for the money a person spends designing and building a firewood processor, cheaping out when designing the hyd chainsaw is a bad place to be trying to save money. You will spend more time waiting on the saw to make the cut than you will spend on splitting the wood. That does not mean I believe you need or even want a hyd chainsaw that is comparable to a 3120 size gas powered chainsaw, but if one is looking at running a .404 size chain, then one should at least try to match a proven platform that will work with a chain of that size. I do believe you will be sorely disappointed if you try running a .404 chain with your little .58 cuin motor.

 

[polemidis]

The majority of wood species is red oak mostly, with white ash, red and sugar maple and with yellow birch following. We will see. I will report back. I just ordered the 15Teeth 0.404 sprocket. And I am 90% sure that I will stick with the 0.58 especially now that I ordered the 15T with the longer pitch of the 0.404 I can get enough linear chain speed. If the 16hp motor is insufficient, Harbor Freight has a cheap one with 22hp, I will just increase the max PSI to 2500. But I think it will be fine, as I know another guy in the forums that has the 0.58 and he is satisfied.

We will see man! Honestly thank you for all your time spending replying!!