Adding weights to bandmill wheels

[woodbowl]

You know how you sometimes get that unwanted dip or rise at a knot when sawing with a bandmill? Having a bit more HP would overcome some of it, but I've been thinking of stored power in the form of weights mounted onto the existing band wheels.

There are issues of course with balancing, rigid mounting and who knows what all. Slinging extra weight around would rob some HP but may be worth it in the long run. Other possibilities are a quick mount system that allows both worlds. An automobile flywheel is already balanced and has a hole in the center. A machined adapter would take the guess work out of the mounting.

Has anyone ever done anything like this before?

[Furby]

I would have to see a comparison of the horsepower lost driving the extra weight vs the gain in the "stored" power.
My guess is it would be about an even trade in this case, or even a loss, but that's only a guess.

[Trent]

The stored energy will be "put in" when the speed is ramped up. After it is up to speed, it will take very little extra power to keep it there. The trick is, how much weight will it take to make a difference? The time duration of the extra power needed is also a big factor.

[Furby]

But that means you wouldn't want to idle down after a cut or anything like that.
You would have to bring it all back up to speed again.
Right?

[pineywoods]

enough weight to do any good, and I'd bet you'd flat-spot the drive belts getting them up to speed. If you are talking pine knots, I find that making sure your blades have plenty of set makes a big difference. The 20 thou set in new wood-mizer blades is marginal for me. (I saw mostly dead pine which makes the problem worse). I put 25 thou set when I sharpen.

[Kcwoodbutcher]

I think it would take a lot more weight than an automobile flywheel to make a difference on any resonable sized knot. By adding enough weight to make a difference you would have to consider the extra strain on the bearings and engine.

[Tom]

I've thought about it a lot of times.  Balancing the wheel scared me off.

You could get away with just balancing the drive wheel and leave the idle wheel alone.

I've not picked one of them up, but, I was told that the idle wheel on my Baker weighs about 200 pounds and the drive wheel weighs about 300 pounds.   That's a big difference between that and the 30 pounds or sothat my LT40 wheels probably weighed.

While I like the ability to brake the wheels, the more I saw, the less important it is to me to stop them on every pass. 

Because I can't stop my Baker wheels, I've learned to operate with them spinning.  The only times I really miss the brake is when a band breaks or I want to perform some maintenance around the bandwheels.

Trent is right about the stored energy.  If you were able to get the wheels balanced, I don't think that carrying the weight would be any problem.

[woodbowl]

The stored energy will be "put in" when the speed is ramped up. After it is up to speed, it will take very little extra power to keep it there.  

Trent, that's the way it seems to me as well. Also, the stored energy would be released when more resistance is encountered, resulting in maintaining a constant RPM ........ for a little while, but hopefully long enough to get away from the trouble spots. Problems may arise when a long grind appears, such as at the end of a log in a swelled butt. If the stored energy is spent too quickly and more of the wide cut is demanded, the weights then seem to become a burden.

[dail_h]

   Most of the ground mills I've run had "balance wheels" belted to them. For a mill with marginal power,or one really trying to get volume out ,they were the ticket. Takes a few seconds longer to get the mill up to speed to start with,but after thats not aeproblem. When the saw got into the log , it would slow down,the wheel would take ahold ,and help through. Then it would speed back up as the carriage was returned,and reset for the next cut. The only thing you had to watch out for was a hot sawyer,who would try to get the saw back in the log before the wheel , and mill came back to speed. Now your poor undersized engine is trying to power the cut,plus bring that big hunk of iron back up to speed. You probably don't want to know how I know this last bit of trivia.
   I still got one of them big ole balance wheels out in the yard,gonna find a use for it one day.
   The extra weight would help on a bandmill,but it probably ain't practical to do.

[jpgreen]

One of my hobbies is cast lead projectiles.

I'm invisioning a mold that makes 2 halfs of a shape, say to halves of a rectangle, that would fit on each side of the bandwheel spoke. Cast those out of lead, clamp that halves together and drill some holes, so they can be bolted to the spoke in the very same position on each one.

With lead projectiles (we call em' boolits) you weigh each one for accuracy, so they are the same weight.  I think this would get you the extra weight without changing the balance.

........... 8) 8) 8)

[Tom]

I would be hesitant to drill the bandwheel to mount weights.  The bandwheel is usually already balanced and they do that by drilling holes and removing material.  A better idea might be a mount that would affix the weight to the spokes by clamps.

when a band breaks, the area around a bandwheel becomes a war zone.  For this reason I believe that any weights need to be protected.  One way would be to place the weight between spokes so that it doesn't stick out beyond the edge of the wheel. 

Just some observances and an opinion.

[jpgreen]

NO!!!!, I'm NOT talkin' bout drillin' spokes... 

These weights would clamp on em'... ;)

Ifn they didn't work, ya take em' off and go fishing..  :D

Don't give me a heart attack Tom..  ;D

[getoverit]

I have sort of a related question....

My bandmill engine has a centrifugal clutch and uses one 4L680 belt to drive it. I think that most of the time the reason I see dips is because the belt is slipping. Do y'all use one belt or would a double belt setup be better?  I suppose if you added weights to the wheels, the double belt would be even more important?

[jpgreen]

Double banded belts are the best. The double belt with the solid banded back.. 

[Larry]

4L belts work great on a washing machine...not so good on a mill.  Belts are designed to transmit only so much horsepower dependent on the pulley size and belt design.  Double pulleys with 4L belts is still going to be inadequate.

Changing to a cog belt might solve your problem.  You would need an AX style or even better a BX (if it will fit).  Your still flying by the seat of your pants...some of the industrial belt suppliers might be able to give you an engineered answer as to what you need for belting.

[slowzuki]

I went through a headache of trying to keep my belts from slipping and ended up with a pair of b's on my 10 hp mill.  I also upsized the drive pulleys.  When they slipped the cutting performance did a nose dive, and so did the blade.

Since fixing the slip, I can accurately determine when a blade is dull now and change it out.

[mike_van]

This question i've thought about for a few days - My old IH baler [and all the others] had flywheels, mainly to get the plunger stroke to work, all that stored energy is needed to chop off the hay where it comes in & compress it into a bale. All these parts though are rigid though, through bearings, whatever - The band mill has a "non rigid" part though, that being the band.  A lot of that stored energy might go to waste because of this. I'm not scientific enough to figure it out, but i think there will be problems that cancel any gains - like the pulling the band as opposed to pushing it? The drive side pulls the band into the wood, where does all that "stored energy" go when hitting a knot? Does it just push the band on the other side of the drive wheel? Any slippage from band to tire also results in losses. I know the large hi-strain bandmills have big heavy wheels, but they have to, to run that 12" x 30' band blade. getoverit  -  drive belt slippage very hard to detect - unless it's smoking or squeeling - I had a little 1/2 hp air compressor a few weeks ago that wouldn't compress anymore - I though it was shot being 30 years old - all it needed was a new belt - :D Theres another flywheel, on there, carries the energy on the compress stroke -   Be nice if someone would do a study on bandwheels though, same mill, etc, etc, but use 100 lb. wheels, then change them to 40's and see if there's a big difference.   I'm sure that someone like Woodmizer has,  they seem to be on top of a lot of the tech stuff in bandmills.  If it's a cost vs gain thing, they've probably done it.

[logwalker]

Mike, you could put a bicycle computer on the idle wheel. I did a post last spring on the install. You can get them for $10 at Walmart. It will show you your actual blade speed which should be about 55 to 60 mph. An if it is slipping it will be obvious. Search for "band blade speedometer" in sawing and it will pop up. Does anyone know how to link to the old post? Joe

[Larry]

Joe, you could make a link to your original post by pasting like this;

https://forestryforum.com/board/index.php?topic=15598.0

Or more better...read how to do it right here...see Insert Hyperlink

https://forestryforum.com/board/Themes/default/help/posting.english.html#bbcref

Than you can do it like this;

Joe's Speed-O-Meter

And thanks for the tip Joe.  I watch my tach, listen to the motor, listen to the band, watch my feed reostat, and watch the speedometer.  Like the speedometer better than anything else as it is my first warning of a band getting ready to take a dive.

[Rail-O-Matic]

I have experimented with adding weight to my home made band mill, I have used car wheels and tyres for the driving force, I have also used an ordinary shop bandsaw and converted it into a horizontal unit, driven by a 13 Hp Honda GX engine, the lighter weight of the conventional unit, were easy to drive, but relied upon the engine to keep things going.

The home made unit with car wheels are six times heavier and stayed in there when the going got tougher, so I can say the heavier wheels are better once into the wider boards and working harder, you must judge the power to the push along rate with a smaller engine, larger engines once at their working speed are no quicker to cut than a smaller engine.

If you cut with a pushed unit rather than a motor fed unit, you have a better feel of things as you progress along the log, the blades also stay sharper longer too, and any obstacles are easier to feel, if you push too hard, the band tends to get lots of very small cracks along it, shortening the life and overall trueness of the band.

On similar sized re-saws, like Stenner and Wilson, they have heavy crowned wheels, but the electric motors are relativly small, something like 10 + horses, the larger weights of the wheels keeps them going, the motor is there to top up the power once cutting begins and strain drops off when the blade is out of the timber.
Check out http://www.amazon.com/Hitachi-CB75F-14-1-Resaw-Band/dp/B0000223KH, 4 inch re-saw 2.8 hp motor single phase.

[Dangerous_Dan]

Why not add weight to the crankshaft on the engine instead of the band wheels?  ???
You could get some big pulleys and just mount them on the crank if you have space.

[Slabs]

Waaal now there Olen!!

Inertia works both ways.  "A body at rest tends to remain at rest until acted on by an outside force".  Namely your motor.  And yours ain't the beefiest motor.  Also a flywheel would be a gyro mounted on a moving platform.  Wander what it will try to do when it's moved at 90 degrees off the spinning axis as you engage the feed and take off down the carriage.

Aw heck.  It would probably take out your blade brake right quickly anyway.