engine horsepower and wavy boards?

[JBeyer]

Trying to understand this wavy board and engine horsepower thing. thot that wavy boards were cause by bad blade tension and pushing too hard or too little when it came to knotty logs/lumber. How much does increased engine horespower affect wavy board chances and what can be done technique-wise if all you can afford is a Hud-son with a 6.5hp Briggs for your own uses and hobby shop? Looking to get myself a mill but only going to pay cash to avoid the pitfalls of trying to make a mill payment. just want to make a few boards, make a few cheap tables... Mainly to spend time with my dad making things and keep myself busy. Any recommendations for smalller mills and their hp?

[ladylake]

 
With small hp it's easy to lug the engine down slowing the band which will cause wavy cuts, if you cut slow enough keeping the RPM's up it should cut straight.   Steve

[ely]

steve is correct, just got to get a feel for the limitations of the mill. also different wood has different sawing characteristics.

[dboyt]

Depends a lot on the size of the log, knots, and species.  If you saw clear yellow poplar or pine-- and stay under 14" diameter-- you should be fine.  You can cut harder woods, if you scale back on the diameter so that you can keep your rpms up and still maintain a decent feed rate.  If you want to cut hickory or pecan, stay under 10" diameter, and you should be ok.  You can do some good cutting with hobby mills, but just because the mill can handle a 20" diameter log doesn't mean that you should cut it.  Overtightening the band to get a straight cut can stress the bearings on the mill, depending on the design, so don't overdo it.  Have fun, get the kinks worked out, and, if you enjoy it, keep an eye open for your next sawmill.

[POSTON WIDEHEAD]

I don't know your situation when it comes to obtaining logs. But if you are able, choose good clear logs with little to no knots. But if you're like me, I don't have much of a choice sometimes......I have to take the good with the bad.

[drobertson]

I have battled wave from time to time, like most probably have. horse power and speeds and feeds always play a part.  I would say make sure you  have a good drive system, that is to say, from engine to belt that drives the blade, try to keep this tight. Knowing nothing about your mill or design, I am blind to your set up but power lose will cause wave. As well as head stability.  It is a touchy feely kinda thing. Keep rpm's up, and a steady feed, feel the load, and check blade clearance on you guides. If you have a good alignment, and speeds and feeds are right, it should make satifactory rough cut lumber.  It might take some tweeking. This part is a pain, but in the end a straight board is sweet,  message or call, if you need to,  no worries.  I have felt your pain, and It kinda stinks.  sharp blades, good alignment, must be first.   david

[Delawhere Jack]

I'm currently running a manual mill with a 13HP Honda engine, I've never felt like it was underpowered. I've cut cherry and walnut up to 22" wide, no problem. On a manual mill the only thing the engine needs to power is the blade through the wood (no alternator, hydraulics etc). It doesn't take very much power to cut with a bandmill.

Good sharp bands and properly adjusted guides are crucial regardless of HP.

On a side note. I see some of the the WM mill offered with as much as 51HP. I can't imagine why any bandmill would need that much power.

[learydeere]

I had a hud-son mill before and had the same issue. I found that what they recommend for blade tension isnt enough it needs to be half again as much and you always need a razor sharp blade on or it will dive on you

[hackberry jake]

My mill came with a 13hp engine, I swapped it with a 20 hp. It does make a difference. The carriage is easier to push and the saw cuts straighter... Don't ask me why. You would think it would just take a little longer to make a cut. Most of my wavy cuts were because of not enough set.

[bandmiller2]

With lower HP mills the set and sharpness of the band is all important.Sometimes with lightly built mills,just tensioning the band will flex the frame and change alignment.I would try different brands of bands,like say Timberwolf or WM and double check alignment.Sometimes we all run into a wavy log. Frank C.

[drobertson]

This is true, I was running re-sharpes on my last batch of pine, pulled them for wave, finished the job, switched to oak, then back to pine. put the same bands back on and they ran like a champ. go figure that one. Not complaining, just head scratching. all the same some logs are just a pain.  some pine has a bunch of resin and is tough to cut.  If a blade acts up change it out, but don't throw it out. Two minutes is all it takes to find out if a blade is right or not. 

[WDH]

I suggest that you shoot for about 15 HP minimum.  With that, you can cut anything that will fit on the mill.  You nay have to look for a used mill depending on your budget.

[tyb525]

On a side note. I see some of the the WM mill offered with as much as 51HP. I can't imagine why any bandmill would need that much power.

Once you run one, or even just watch one...you will know. It will leave your 13hp in the dust. No offense intended, I have a 10hp, and I'm not afraid to admit it is slow even with everything perfect and perfect logs!

Some sawyers out there do it for production, and they need that power. Just like some loggers need a semi to haul logs, even though a 1ton flat bed can haul a few logs also.

[drobertson]

My 51 hp has cut wavy boards, not due to  excessive feed or speed. just weird logs or weird blades. or bad adjustment.  Sharpe blades, good adustment and the right feed will fix this problem, feel the cut, manual or power, and it will work. Our mills are on the feel basis anyway, regardless of the hp. If you want 20,000 ft a day go for a circle mill.  Other wise find the honey spot, stay with it and be patient.  Just my opinion. Not saying you are hogging the cut, just trying to make a point.  It can get frustrating, I have been there. Take a breath and a break, and make small ajustments.  Just remember what you have done.   

[Delawhere Jack]

On a side note. I see some of the the WM mill offered with as much as 51HP. I can't imagine why any bandmill would need that much power.

Once you run one, or even just watch one...you will know. It will leave your 13hp in the dust. No offense intended, I have a 10hp, and I'm not afraid to admit it is slow even with everything perfect and perfect logs!

Some sawyers out there do it for production, and they need that power. Just like some loggers need a semi to haul logs, even though a 1ton flat bed can haul a few logs also.

What I don't get is how adding 20HP more can make a band cut any faster? There are inherent limits in the band speed and feed rate, regardless how much horsepower is behind it? Am I wrong?

I see it as a 1972 Nova with 10" slicks and a 4.11 rear. (or whatever). If 700HP will burn the tires off the rims, what good is 1,500HP going to be in the same car?

Maybe I'm just dense..... :-\

Anyway, I'm more than doubling my HP next week, and getting hydraulics!  ;D

T- 8 days until "Christmas"!!

[Leigh Family Farm]

I just have to say this post is educational to say the least. Thanks to all you guys for helping me learn the industry. Keep it up!

P.S. Go big or go home, right?  ;D

[tyb525]

There really isn't a practical limit behind feed rate and speed ;D

The blade on the 51hp mill will take a much bigger bite per tooth than a 13hp mill. Also the blade will probably spin faster, both factors increasing cutting speed. Sometimes they use 1 1/2" bands, sometimes not.

You'd be amazed at how these bands can perform under pressure. A low HP mill is probably not pushing the band at all, just the motor. Actually, having to cut slowly due to lack of HP can cause a wavy cut also, and heating of the blade. That is why they are much more sensitive to dull bands.

51 horse mill doesn't really care as much if it has a dull band, but it shows up in the lumber as waves.

[thecfarm]

I have a manual mill with 20hp. Some knots are hard. I kinda feel it's the speed I am pushing. Too fast will make it dive I feel. But so will a dull blade too and many other things too.

[Brucer]

What I don't get is how adding 20HP more can make a band cut any faster? There are inherent limits in the band speed and feed rate, regardless how much horsepower is behind it? Am I wrong?

The secret to making a small band cut straight is to keep the cutting speed at or above 25 m/s (5000 ft per min). If the band slows down for any reason it will start to wander, no matter how sharp or how well aligned.

Things that will slow the band down are:

• wide cuts
• hard knots
• feeding it too fast into the wood
• dull teeth

It's torque, not horsepower that pulls the blade through the wood. Horsepower is just torque multiplied by speed (or put another way, speed is calculated by dividing avaliable horespower by the required torque). When the blade runs into something that's tough to saw it requires more torque, so that slows the blade down. The engine responds by opening the throttle to provide some extra horsepower, thereby providing enough torque to get the blade back up to speed.

If you hit a hard knot, the blade will slow down before the throttle opens up enough to get the blade back up to speed. So you get a ripple.

Wider cuts and dull blades demand more torque. If you're trying to push your head too fast the engine will be maxed out. No more horsepower available so the blade will start to slow down. Again, you start to get ripple.

A bigger engine will deliver more torque at a given blade speed. That allows wider cuts, or faster cuts, or cutting with dull blades. It might not help a lot if you hit a hard knot because it still takes time for governor to get the engine back up to speed.

Diesel engines have better torque characteristics than gas engines. They won't "notice" knots as much so they are less likely to cause ripples when cutting wood with big, hard knots.

Electric motors (and steam engines ;D) have the best torque characteristics of all.

[JustinW_NZ]

Agree with the above,

I have a 43HP diesel and just got through sawing up some frozen hardwood.
You could notice the "half frozen" sap in the center as the motor would bog down a bit and if u didnt back off I would get some mean blade diving.

So I think as others have said, listen for the motor and watch the speed and all things being equal it should be fine.

Cheers
Justin

[ladylake]

On a side note. I see some of the the WM mill offered with as much as 51HP. I can't imagine why any bandmill would need that much power.

Once you run one, or even just watch one...you will know. It will leave your 13hp in the dust. No offense intended, I have a 10hp, and I'm not afraid to admit it is slow even with everything perfect and perfect logs!

Some sawyers out there do it for production, and they need that power. Just like some loggers need a semi to haul logs, even though a 1ton flat bed can haul a few logs also.

What I don't get is how adding 20HP more can make a band cut any faster? There are inherent limits in the band speed and feed rate, regardless how much horsepower is behind it? Am I wrong?

I see it as a 1972 Nova with 10" slicks and a 4.11 rear. (or whatever). If 700HP will burn the tires off the rims, what good is 1,500HP going to be in the same car?

Maybe I'm just dense..... :-\

Anyway, I'm more than doubling my HP next week, and getting hydraulics!  ;D

T- 8 days until "Christmas"!!

Sounds like next week you'll be finding out first hand how much extra HP helps cutting speed and accuracy..  My 27 hp Kohler was underpowered in wide cuts in hardwood, my Isuzu diesel make those cuts way faster and straighter.  I think a 1-1/4" band would be maxed out with around 35hp  with the 50hp diesels better suited for 1-1/2 to 2" bands.   Steve

[thecfarm]

Justin,you got me for a second with that frozen wood. ;D In a few months I'll  be in the frozen wood and you'll be in summer weather.

[JustinW_NZ]

Justin,you got me for a second with that frozen wood. ;D In a few months I'll  be in the frozen wood and you'll be in summer weather.

haha yip - bring on summer!  8)

[Delawhere Jack]

On a side note. I see some of the the WM mill offered with as much as 51HP. I can't imagine why any bandmill would need that much power.

Once you run one, or even just watch one...you will know. It will leave your 13hp in the dust. No offense intended, I have a 10hp, and I'm not afraid to admit it is slow even with everything perfect and perfect logs!

Some sawyers out there do it for production, and they need that power. Just like some loggers need a semi to haul logs, even though a 1ton flat bed can haul a few logs also.

What I don't get is how adding 20HP more can make a band cut any faster? There are inherent limits in the band speed and feed rate, regardless how much horsepower is behind it? Am I wrong?

I see it as a 1972 Nova with 10" slicks and a 4.11 rear. (or whatever). If 700HP will burn the tires off the rims, what good is 1,500HP going to be in the same car?

Maybe I'm just dense..... :-\

Anyway, I'm more than doubling my HP next week, and getting hydraulics!  ;D

T- 8 days until "Christmas"!!

Sounds like next week you'll be finding out first hand how much extra HP helps cutting speed and accuracy..  My 27 hp Kohler was underpowered in wide cuts in hardwood, my Isuzu diesel make those cuts way faster and straighter.  I think a 1-1/4" band would be maxed out with around 35hp  with the 50hp diesels better suited for 1-1/2 to 2" bands.   Steve

That's what I was thinking. Eventually you reach the limit of how much dust the gullet can remove....
I wasn't considering that the 51's were using larger bands.

[dboyt]

Gotta remember, too, that the bigger mills are doing more than just cutting wood.  You've got the carriage feed and hydraulics taking power, as well.  My old TimberHarvester took about 8 hp just to keep the hydraulic pressure up, whether it needed it or not.  I didn't complain about it when I was loading, turning, and clamping logs by just pushing a lever, though.