Wide Throat Bandsaw Mill Ideas

      Thoughts on the technical challenges of building a mill capable of producing up to five-foot slabs. November 3, 2010

Question
Does anyone out there own a bandsaw with a 36" or wider throat? I am looking to saw through logs to make table tops. I'm considering making or having made a bandsaw with 48"-60" throat. This is not for high speed/production but the quality of cut is important, any thoughts on using 1 1/2" blades with a cut this wide? I would also consider hiring someone to do this work, but I also don't want to use a chainsaw mill due to kerf loss. Any thoughts are appreciated.

Forum Responses
(Sawing and Drying Forum)
From contributor G:
Most mill makers are building portable mills. The wide throat mill would be over-width. My mill is 30" and at the limit for trailer width. I suppose you could get an over sized load permit. I am sure Mighty Mite would make you a special mill that would be bigger, they could come up with a rotating saw for trailering. Likely the Gen III would be the one to modify.



From contributor E:
Hud-son Forest Equipment has an Oscar 52" that fits your specs.


From contributor J:
The Woodmizer LT40 cuts up to 36" and it comes manual or hydraulic.


From contributor K:
I don’t have a Woodmizer so I could be wrong , They can cut a 36" log but the distance between the guides is smaller I think?


From contributor A:
About the widest cut on a Woodmizer is 27 inches. It is the throat opening that the questioner is talking about and he is looking for an opening of about five feet. The problem is going to be pulling a band through that much wood even a two inch band. There are some very large band mills that cut seven feet but they have blades eight inches wide and take out about 1/4 inch kerf and cost six figures. A dedicated slabber like a Lucus or a Peterson would be a better bet. There would not really be that much kerf loss and you would produce a flatter cut.


From contributor T:
You can cut that wide but doing it with a 1.5" blade is not a good idea. I have used a bandmill with 36" cut and it would start to get wobbly at full width. You end up wasting more material than a chainsaw mill. If you have a wide band like 4" plus with high tension you can cut wider.


From the original questioner:
I appreciate the responses. I would be primarily cutting cherry, walnut, and maple. The mill will be set up stationary. The mill I want to have built would be manual operation so I don't know if beam strength would be an issue? By the way I have successfully used Woodmizer mills at the max throat 24"-27" with no waving cuts using 1 1/4" blades (sharp blade and slow feed rate).


From Gene Wengert, forum technical advisor:
I have seen saws with this large an opening, but they were using 6-foot diameter wheels and 6" to 10" wide bands. A large saw is needed to keep the saw from moving in the cut deep inside the log. A wide saw is stiff and can also use a lot of tension. Further, the back of the band with a wide saw will help steer the blade. Basically, you can look at old saw designs (especially in the Pacific Northwest) and use them rather than reinventing the wheel. For large hardwoods in the east, in the past we used a circular saw (about 20" useful opening even with a 60" diameter blade) and then a top saw. A bandsaw to do what you want was too expensive, especially when only a few logs were so large.

Have you considered using a large chain saw and then machining the pieces (perhaps using a floor sander) to the required thickness? Sawing is indeed a difficult situation for you, but I suspect that drying will be even more difficult. A cut near the center of a log will certainly cup, especially with a 36" diameter log.



From the original questioner:
Actually, the boards from the outside of the log tend to cup more. The center boards usually split near the pith, if anything. I have considered chainsaw mills. Saws with enough power to run them are costly as are the bars and chains. I believe there would also be more maintenance (sharpening) related to the chain as well as wear to the bar. Dedicated slabbing mills like the Peterson and Lucas are quite costly as well, and I don't have the volume of large logs to justify the expense.


From Gene Wengert, forum technical advisor:
Cupping is most likely from flatsawn pieces cut from the center of the log. The risk of cupping when the piece is more than 12" to 15" from the pith is not likely to cup at all.


From Gene Wengert, forum technical advisor:
In order to saw a 36" wide (or more) piece of lumber, the power will be quite large. It will take a wide and thick saw blade to transfer that much power.


From contributor D:
It can be done: I built my first mill in1986. Forged 30" band wheels from 3/8 x 3" steel and welded in spokes - 36" between the guides. I used a 3" wedge set band blade and 20 hp engine - all manual. It was accurate to 1/16". The largest log I cut was 54" diameter. I made a lot of 36" wide boards which eventually shrank to 34 1/2" and were used with wooden hinges for "1 board doors" in a log cabin.


From contributor A:
Well since the $20 grand for a dedicated slabber is too high the why not build a pit saw? Or a large powered bow saw? You could take one of my broken blades and build a frame like a coping saw head and make it slide back and forth on a rail and then just track it through the log. They used to split large logs with pit saws and saw lumber. There was one here powered by a water wheel. Like most things it comes down to time and money. The more money you spend the less time it will take to do it. But with a pit saw it could be done in a day. With $20 grand the log will be sawn in less than an hour.


From contributor R:
I built mine just so I could do what you are wanting to do. The head also has enough travel/adjustment that I can run standard 13'2" blades most of the time. Actually I can run just about any standard blade. My head rig is 7' wide and the drive wheel is mounted inside the upright post. The idle wheel can run out past the other post (but that would be useless).

Be warned what has been stated is true. The blade will cup inside the cut, it is very slow, and it does take a lot of HP to pull the blade through the cut. You'll need to wedge the slab as you cut. If you have a band break in the cut, good luck getting it out. Also loading big logs is hairy even with a mill built out of 4x8 3/8 tubing.

You should be able to build a chainsaw slabber for under a couple grand if you use a small i/c engine instead of saw heads. You should be able to find harvester hubs and sprockets that would fit a 20+hp Briggs or Kohler. Or you can drive the chain via a jack shaft set up.



From contributor U:
A couple of years back we did tackle a job to make table tops out of a 4' diameter white oak - we ended up going with the old Alaskan jig and a big Stihl saw (MS 66 - now 660). We ordered ripping chains from Baileys and had them re-sharpened as needed at a local place near us. Over the course of two or three days we whittled that 10' log down into lots of 6/4 and 8/4 boards with the widest ones being 48". With the infrequency of need to cut that wide, we thought it best to go with the chainsaw mill and that did work out real well. There is heavy kerf loss compared to the band mills, but there were too many advantages to pass up the chainsaw for a band on these sized logs.

We could haul the chainsaw and jig to the tree, verses the other way around - which is a big deal with large trees, and the coin factor. It cost us very little to make those wide boards versus trying it with a specialty band mill. The handling and drying were by far more of an issue than how to do the cut for us though. That being said I am much happier behind the control head on the Woodmizer 40 Super, buzzing through the normal sized logs, spitting out great lumber day in and day out than dealing with the hog logs.



From contributor S:
I have both an Alaska mill - 56" with a Stihl 880 and a Woodmiser LT40. The comments regarding both are pretty accurate. The LT40 will cut between 24-28" depending on the position of the log. The Alaska mill works well but takes a large kerf. The Alaska mill is fast and can be rigged to function with one operator. A large Alaska mill with a good powerhead will cost about $2K.


The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor H:
I built a portable bandsaw that cuts up to 60". It is electric over hydraulic and I run 2” and 3” 042 blades. The key is to have the blade perfectly level to the deck. It cuts perfect, but it did cost about 20k to build and was completed in three months. Keep the tooth speed under 5,000 and buy sturdy guides.



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