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Need help on engine size for Mighty Mite bandmill - Longish

Started by rfalk, January 24, 2008, 03:02:05 PM

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rfalk

Hi,
I have been reading the forum for some months now and have learned a lot. I thank all of you for that.  I now have some questions regarding engine size for my bandmill and would appreciate any advice you can give.

I have a late 80's Mighty Mite III that I purchased used last fall. Its pretty heavy duty, trailered, with hydraulically driven feed and carriage. It has 18' wheels, a 2" blade (13'10" long), and is powered by an 18hp Kohler Magnum engine (runs both the blade and hydraulics).

I am a hobbyist and am not looking at production sawing, however I would like to get to the point where I could quarter saw some of the bigger oaks that come my way, if possible.  I have sawn a few smaller (12") black cherries and the mill seemed to saw straight and without waves....well, that is, after I got the blades sharpened properly and got the feed rate correct. More recently, I have tried to saw frozen white oak and had nothing but trouble. Wandering cuts and stopped the blade several times in a 10" wide cant.

I realize my blades might not be ideal for frozen white oak (0.020" set and 10 degree hook), but they were sharp (brand new, in fact). While blades may be part of my problem, my question to all of you is: Am I underpowered? Or, conversely, am I running too wide a blade?

I am thinking of replacing the 18hp (30 ft-lbs of torque) with a 30 hp Kohler V-Twin (47.5 ft-lbs of torque). I called Mighty Mite and their current model (IIIa) has a 25hp engine....they thought more power would help, but thought anything over 30hp would be unnecessary. They also suggested that I could go to a 1-1/4" blade....however, their conversion kit to do so is $1400.

1-1/4" blades are cheaper than 2", but is there any other reason to switch? Do wider blades require more power? If so, maybe I am better off staying with a 2" blade and a getting a larger engine.

Any thoughts? Would love to hear from any Mighty Mite owners out there.

Thanks, Bob
Wood engineer, woodworker, chainsaw miller, bandsaw miller, all around lover of wood.
Stihl 026, 361, 076 AV

deeker

I have used both 1 1/2" and 1 1/4" blades on the Norwood LM2000 with the 23hp briggs.  The smaller blade is all I use now.  Less problems, less blade for the saw to pull.  Cookssaw mfg might offer a kit to change to smaller blades at a lot lower cost.  When my blade has stopped in the cut it was because the rpms were too low, and the tension on the bandwheel driving the blade was too low.  Before we got the problem fixed, by checking the rpms and tension we went through a clutch.  After getting the blade up to the required rpms and the bandwheel tension corrected, over a year ago no problems since.  We have cut cedar, dry hard Mt. Mahogany and several others.  Also the blade "lube" helps to to keep the blade cool, not so much as a lube.  Good luck.


Kevin Davis
Ruff Cutts
To those who fight for it, life has a flavor the protected will never know.  On an empty C-ration box.  Khe-Sahn 1968

bandmiller2

Bob,I to had a problem with oak ,pine would cut perfect,oak would take the dive.I called Art at timberwolf [on long island N. Y.]he sent me a couple of blades to try.The blades he sent were 11/2"wide 1" tooth spacing worked like a champ perfect cuts, he said they wouldn't  do as well in pine .I'am no authority Bob but it seems 2" bands are a little heavy for your mill and power especially 18" wheels you won't get the band life you should and their too expensive.11/2 bands are a good compromise if their not the heavy gauge ones.I have never tried 11/4 bands on my home built bandmill so I can't comment .Do you sharpen your own bands Bob,if so you could try different hook angles.There are many here that know much more than I I'am sure they will chime in shortly.Thanks for your help on circular blade hammering,Rusty said he didn't know much about it ,found my old smith I used 25 years ago.Their is really nothing written about how to tension a blade just why and tempting tidbits pretty well kept secret.Good luck Frank C.
A man armed with common sense is packing a big piece

bandmiller2

Bob read your question again,more power is usally a good thing,but not the cure all same problems just happen faster.Sometimes frozen wood gives everyone fits,myself I just set it aside and let it thaw,cut something else.A marginal power scorce keeps a sawyer honest you have to have a sharp band,has to be set right ,right hook and mill in good shape or you don't cut worth beans.
A man armed with common sense is packing a big piece

rewimmer

Hello rfaulk,
Just wanted to add a little to your post. I like horse power and will take all I can get. The main thing is that your 1 1/4',1 1/2", etc. blade should not exceed 5500 Surface Feet Per Minute in soft woods and in real knotty pine I have to slow it down at times because of the knots. In Hard woods such as dried oak, hickory, etc. I drop my SFM by about 20%. You just have to learn your mill and what it takes to cut good lumber and get the most BF from the blade. And the same goes for the feed rate, you will get a feel that will give you good lumber and the most BF per blade. With a 2" blade it would seem it would be a little under powered for me. I am running a 27 HP Kohler on a 1 1/4" blade and it seems to be a good combination. I also feel that you could cut good lumber with the 18 HP if you take your time and not over push your mill.
Robert in Virginia

rfalk

Thanks for the replies! Sounds like I need to think about engine size and my sawing technique. Bob
Wood engineer, woodworker, chainsaw miller, bandsaw miller, all around lover of wood.
Stihl 026, 361, 076 AV

rfalk

I wanted to complete this thread by letting all interested know that we finally got a 30hp Kohler on our Mighty Mite mill to replace the 18hp.....wow, we were able to saw nicely through 16"+ of White Oak....we had to keep the feed rate extremely slow to clear saw dust, but we now don't have the mill bogging down trying to power both the blade and hydraulics.......seems that more horsepower really helped solve our problem.

We bought a rebuilt Command Pro 750 for about $1000....significantly less than a new one...if interested in a new engine for a mill, check out M&L Saw Service in Iowa. Here is their Ebay store:


http://stores.ebay.com/Small-Air-Cooled-Engines_W0QQssPageNameZl2QQtZkm

Engine delivered was as advertised. Michael, the owner, seemed very honest and helpful. BTW, i am not affiliated with the company...only bought an engine from him and thought I would pass on the good luck we had. Cheers, Bob
Wood engineer, woodworker, chainsaw miller, bandsaw miller, all around lover of wood.
Stihl 026, 361, 076 AV

Dave Shepard

Glad to hear you got it sorted out. What blade did you end up running?


Dave
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

rfalk

We are still running a 2" blade...have about 20 of them and changing over to 1-1/4 will require machining of the band wheels and guides.....may do it in the future, but will wear out the 2" bands we have before making the investment. bob
Wood engineer, woodworker, chainsaw miller, bandsaw miller, all around lover of wood.
Stihl 026, 361, 076 AV

Tom

Making the guide wheels match the blade will be important, but, I wonder if you might get away with using the same band wheels.   When you put a larger band on a small wheel, you cause the band to cup as all of the pressure is in the middle.   If you put a smaller band on a larger wheel and can get it to ride far enough foward to keep the teeth off of the wheel, It seems that it would still work. Don't you reckon? :)

rfalk

Tom,
I had the same exact idea.....I figured the 1-1/4 blade should center itself even though our Mighty Mite wheels don't have much crown (unlike a shop bandsaw)....so, I bought a 1-1/4" blade to fit as an experiment....it was a Timberwolf and I tried their low tension method, adjusted the guides as best as possible (the guides moved to accommodate the 1-1/4" blade, but at full retraction only sat a few millimeters behind the set of the tooth).....seemed to run ok....blade was stable for awhile....about half way down the log, hit a knot and the blade shifted back (maybe too little tension from the Timberwolf method?) and between the guides which took all the set out of the blade.....I ended the experiment at that point......

Mighty Mite tells me the biggest single improvement they have made to their bandsaws is going to a 1-1/4" blade....seems to be more forgiving (as in, not everything has to be in exact adjustment for it to cut), so they said.....however, I am still confused about the disadvantage of a wider blade.......resaws seem to have quite wide blades.....bob
Wood engineer, woodworker, chainsaw miller, bandsaw miller, all around lover of wood.
Stihl 026, 361, 076 AV

Left Coast Chris

Bob,

From a mechanical standpoint, the wider blades tend to be thicker also.  That takes more horse power to run them and the thicker blades will generally not take the flexure cycles the thinner blades do.  Think about the big resaws and how big in diameter their wheels are.  That is so the thicker blade will not flex so far as it is riding on the wheel.  With 18" diameter wheels the blade is doing alot of flexing as it rotates.  This creates heat, heat expands the blade and tension goes down if your adjustment is manual (like mine).

Also, the frames of the smaller mills are only so strong and can only pull so much tension on the blade without the frame starting to distort or twist.  Blade tension is measured in psi.  If your frame can only pull x number of pounds on the blade before starting to twist or deflect the psi = pounds of tension/cross section of the blade.  The less wide and thinner blade will have more psi in tension with the same frame stress. 

My home made woodmiser clone has a 2x6x3/16" tube for the frame arm between the wheels and I can crank the tension so the frame begins to twist.  That maxes out my tension.  I run 1-1/2" blades because I got some used ones but I know my blade tension situation would be better with 1-1/4" wide and thinner blades.  That would probably help my peformance.

Also,  you mentioned you had to slow down to clear the sawdust.  The gullet depth is an issue there.......... I have had good luck with woodmiser blades but we all slow down with oak.  I also have a crank with a rope to move the head up and down the monorail.  I am just a hobby sawer but the manual aspect lets me feel how the blade is feeding in the wood and I slow down based on how hard Im cranking the head along. 

Food for thought.
Home built cantilever head, 24 HP honda mill, Case 580D, MF 135 and one Squirel Dog Jack Russel Mix -- Crickett

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