Bandsaw Mill Design and Build

[Brackish]

Hi There,

I spent some time this morning playing with my design and made quite a few changes to the saw.

This go round I did not connect the sawhead to the aft carriage posts to eliminate binding.
I reduced the saw beam to 4x2 rectangle tube but added 2x2 square tube to the bottom of both ends so that I could; on the idle side nest tubes on the for tensioning and on the drive side to match the height.

I added 2x2 square tube to the front of the saw beam to mount blade guide arms.

I do not show both band wheels wheels, a jack or porta power for tensioning, motor plate, or guard provisions on it nor have I done anything about a raise/lower system (probably acme rod?)

Thanks for your input.
Mike 
r>
 

 

 

 

[Ljohnsaw]

Looking pretty good!  Make sure however you mount your drive and idle wheels that there is a way to adjust the tracking.  Can be as simple as having one of the pillow blocks be movable with an adjustment bolt pushing on it.  Only need one on each end to be adjustable.  Needs to be easy and very fine adjustments.

As far as your blade guide arms.  Assuming you will have your backstops on the same side as your drive wheel, you don't need that guide arm to be adjustable.  Just make it so you have the max room on the bed.  Typically inline with the backstop or very close to it.  Being on the outside would be better when you have a big log that sits above and beyond the backstop.

As for the adjustable, we had a long discussion about that on another thread.  Here is a link to the start with pictures from my mill (V2.0): Sliding guide, part 1  and then continued later in the thread with a bit more description of how it works: Part 2: the rest of the discussion  I'm not saying this is the only way or the best, but I did the tube-n-tube on my first iteration.  Doing it this way was much easier, lighter to build, way easier to adjust and more stout.  It also affords the ability to motorize it so you can adjust on the fly!  This is also the way WM does it on their mills, so it must be good!

[Brackish]

Looking pretty good!  Make sure however you mount your drive and idle wheels that there is a way to adjust the tracking.  Can be as simple as having one of the pillow blocks be movable with an adjustment bolt pushing on it.  Only need one on each end to be adjustable.  Needs to be easy and very fine adjustments.

As far as your blade guide arms.  Assuming you will have your backstops on the same side as your drive wheel, you don't need that guide arm to be adjustable.  Just make it so you have the max room on the bed.  Typically inline with the backstop or very close to it.  Being on the outside would be better when you have a big log that sits above and beyond the backstop.

As for the adjustable, we had a long discussion about that on another thread.  Here is a link to the start with pictures from my mill (V2.0): Sliding guide, part 1  and then continued later in the thread with a bit more description of how it works: Part 2: the rest of the discussion  I'm not saying this is the only way or the best, but I did the tube-n-tube on my first iteration.  Doing it this way was much easier, lighter to build, way easier to adjust and more stout.  It also affords the ability to motorize it so you can adjust on the fly!  This is also the way WM does it on their mills, so it must be good!

Thanks for your response.
For tracking adjustment. On the idle side the 2 nested square tubes that provide tension adjustment will be tied together with plate and the pillow blocks bolted to the plate. I was thinking I could adjust the tracking with the elongated holes of the pillow blocks and shims.
Is there no benefit to having both blade guides adjustable?
Does anyone clamp the log both sides not right up on the backstop and cut nearer the center of the log bed? In the case where there is wane or live edge both sides of the cut? I have been doing a lot of live edge epoxy slab work for restaurant bar and counters and I will be cutting slabs like that as well as dimensional lumber.

[RetiredTech]

Also, allow enough length between carriage wheels to avoid the carriage getting too tippy front to back, especially when the saw head is raised quite high.

I second. I originally made mine too short in front and had it almost tip over while working on it. I added a piece of channel under the full length to extend the wheels out further.

Does anyone clamp the log both sides not right up on the backstop and cut nearer the center of the log bed?

I read on another build where the builder put his backrest on the side where the blade enters the log. He would make his first cut then when he turned the flat side against the post the blade would enter the cut on the fresh cut side instead of the bark side. I would think you would need a really good clamping system for that to work as the blade would be constantly trying to pull the log away from the post instead of pressing it to it. His idea was the blade would stay sharp longer.

[Brackish]

The saw frame size or carriage is kinda arbitrary at the moment.

The width i will determine after i'm satisfied by the design, I will figure for a standard blade size by essentially adding or removing (in design) width of the track the wheel base width the carriage cross bars and the saw head beam while leaving the ends and pillow block design alone.

the height of the carriage frame and length fore and aft I could use some suggestion. 
I am a little curious as to where the balance will be and not sure yet how long to make the wheel base fore and aft.

I think the saw bed will be out of 24' stock in order to cut 16' logs that means 4' before and 4' of track available before and after the log. but should the base be 4'? 

I have also seen some suggested methods of capturing the carriage on the track that I will consider 
Mike

[Brackish]

Does anyone clamp the log both sides not right up on the backstop and cut nearer the center of the log bed?

Posted by: RetiredTech
 « on: Today at 05:15:24 PM 
I read on another build where the builder put his backrest on the side where the blade enters the log. He would make his first cut then when he turned the flat side against the post the blade would enter the cut on the fresh cut side instead of the bark side. I would think you would need a really good clamping system for that to work as the blade would be constantly trying to pull the log away from the post instead of pressing it to it. His idea was the blade would stay sharp longer.



The idea is that some on my intended use is to produce slabs with live edge on both sides, not cutting with a cut edge on the backstop.
like these bar room tables I am epoxying this week. (had to buy this >:( from a nice guy tho!)
for

 

[RetiredTech]

I didn't realize you were after a live edge on both sides, I was picturing something like a bar or mantle piece with one flat edge and one live edge. I'd still go with the backstops on the side the blade exits. There's a lot of people on here smarter than me, and that's the way I see most mills made.

[btulloh]

The log doesn't have to be centered on the bunks to get two live edges. It would be overly complicated to have movable backstops. There could be some benefits when sawing gnarly stuff with protrusions, but I don't think it's worth the extra complication.

On the other hand, I would like to see somebody build one that way.  

[Ljohnsaw]

I think the saw bed will be out of 24' stock in order to cut 16' logs that means 4' before and 4' of track available before and after the log. but should the base be 4'?

There are a couple ways to do this.  You need to be able to position your head (at the start of the cut) such that you can load the log.  So, the distance from the rear wheel to the front of the saw frame is what subtracts from your bed length.  At the far end the distance from the front wheels to the back of the blade is what you subtract.  You can raise the blade and run the head back to the start.  Not the most convenient but that determines the max log you can cut.  Would be better to subtract the amount from the front wheels to the back of the saw frame - where you can clear the log/board for easy removal.  And then, probably better to give yourself at least a foot or two wiggle room to load logs so you don't knock your saw head off the track, so I've been told :

The other way is to add a section of light weight track at each end to "park" the saw head.  It doesn't need to be as strong as the main track as it is not supporting a log.  Just the weight of the head.  These sections could also be removable and/or fold up for transport or storage.

Also, think about the geometry.  The farther the wheels are apart (with the blade being somewhat centered), the less affect irregularities in the track have on the cut.  Not saying you have any, but if you have sections (like me) that have a little bump at the connecting point, that distance will reduce the effect down by at least half - making it unnoticeable.

[Crusarius]

My legs under my 2 post mast are 39" long. The legs are not centered on the skate.

I used 6x2x.188 for my bed. I can support one corner of the bed and jump on the opposite and there is no visible deflection.

For my main rails its is the 6x2x.188 tube with a piece of 3/8" flat stock welded to the tall side. If you do not full weld everything and you space your welds out you should not have any trouble at all with heat affected distortion.

Here is a picture of my wheel / skate setup. The green piece is a tipover prevention and works very well keeping the head on the tracks. The aluminum plate is my rail scraper. It actually sits against the rail normally, not sure what happened in the picture?


 

When I first built my mill I made it so the fixed guide was in line with the back stop. That was a HUGE MISTAKE. Every time I was cutting a log (since we all know how straight they look till they hit a sawmill) the log would protrude past the backstops and jam the carriage on the guide wheels. I ended up moving the head over 2.5" to avoid that problem.

Take a look at my build. It covers most of the question you have. See sigline for link.

[Crusarius]

Here is a picture of my bed in the early construction phase.



 

And here is the picture I wanted to post for the rails.


 

Also, check out my gallery for a ton more pics.
https://forestryforum.com/gallery/thumbnails.php?album=7990

[RAYAR]

I spent some time this morning playing with my design and made quite a few changes to the saw.

I reduced the saw beam to 4x2 rectangle tube...

...nor have I done anything about a raise/lower system (probably acme rod?)

Thanks for your input.
Mike

I would reconsider that 2X4 rectangle tube to something much more stout, as the is a tremendous amount of force on this piece from the tension of the blade.

My mill was built using a garage door lift system using cable for the head lift system. It works good, but I believe the best system would be chain and sprockets, minimum schedule #40 chain size.

My thoughts on these
Ray

[Crusarius]

My saw frame uses 2x2x.188 for the frame. The pillow blocks are bolted to that so there is only the offset of the pillowblock height. I do not have any noticeable deflection.

[Brackish]

My saw frame uses 2x2x.188 for the frame. The pillow blocks are bolted to that so there is only the offset of the pillowblock height. I do not have any noticeable deflection.

Crusarius 
I just read thru your build thread. Nice Work.
any final thoughts on the 2 post design? 
I saw your comment about it walking.
is there any issue with your saw beam being so far ahead of the posts? is it front heavy or did the engine etc balance it out?
My design is considerably different in that its a four post the motor will be facing the other direction the and the band wheels will be closer to the 2 posts supporting the saw head (at first I drew it as using all 4 posts capturing the saw head with tube in tube or 'nested tubes' but I was advised to only capture it with 2 posts to avoid binding while raising and lowering.
I like your backstop and log clamping and you overall did nice work.
Thanks, Mike

[Brackish]

I suppose id probably want the saw to be slightly forward heavy so that the nested tubes normally sit in the position that they would be driven into by the force created by pushing the blade into a log?

[Crusarius]

2 post design. I like it. Would not be opposed to using it again. The best part about it is the sawframe is in front of the mast so the blade has full access to change. I do not have to snake it around a frame.

The walking was early on, I think I ended up fixing that by shimming the skate wheels so the flanges on the wheels did not rub on the track sides. The entire carriage moves easy enough that a steady breeze will move it or if the mill is not level.

It is definitely front heavy. and because of this it does not go up as fast as I would like (threaded rod binding). I used to have the tube in tube design you are going for and it worked well with no problems. I ended up switching that out for cam followers because the tube in tube just kept shaving the paint off the mast. If  I was able to balance it better this would not be a problem.

With my design (Linn Lumber design) the engine drives the saw the opposite direction as most other manufacturers. This really isn't a problem except for the fact that then engine is on top of the sawframe making it very unbalanced. This is not a problem with the leg setup I had. The biggest issue I do not like about it is the fact I have to flip every blade to put on the mill, then flip it back to sharpen. My next mill will not have the engine in that orientation.

The carriage is very well balanced with the way I built the legs. I do however, highly recommend a retainer of some type to keep the carriage on the mill. I have had some issues that without those clips would have meant derailment for sure.

Keep in mind you can do a lot more with geometry than you can with over sizing components. For example my legs are 39" long. But the mast is roughly 12" from the one end. this gives me a solid 24" of support under the sawframe. What you do have to watch for though is the blade hitting the skates. That is why my bunks are 2" higher than the side rails.

The backstops, I would not do that again. they work and are nice to have them all connected but the rotating is a nightmare and a half to try to align. I had them at 90 degrees before the mill got final paint. I have not been able to get them perfect since.

Thanks for all the praise on the build. I learned a lot and really enjoyed doing it. One day if someone wants to buy this one I am planning on building a very different one.

[Crusarius]

Brackish, that is not necessary. Personally I would prefer the tubes to be floating inside each other. As soon as you contact the log and start sawing it will push against the uprights taking care of the what you want. The other thing is to if it is slightly front heavy then you will get friction causing raising and lowering to take more work.

[Brackish]

I think I am still going for the tube in tube design at the moment but I still have some uncertainty on the balance between too tight and its binding and too sloppy.
Would sloppy lead to more band blade marks in the slab?
how much does a constant feed speed help in a smoother cut? i.e. does a power feed create a much cleaner cut?

As far as ACME rods for the lifting
What size rod should I use? is there a more common or preferred size or should I just be looking to satisfy the strength needed.
How are ACME rods terminated into a bushing at the bottom and top? 
How are ACME rods adapted to a chain gear at the top?
Mike

[Ljohnsaw]

Slop is not bad. Binding is bad! I have movement and I don't think it affects the cut.

My second set of ACME rod is ¾" IIRC. One inch would be better. Get the longest nut you can in bronze for better wear. Weld or use a coupler with set screws to attach regular rod to the end. If you had access to a lathe, turn the end down.

A thrust bearing on the bottom would be great. Set screws for the sprockets as well. You MUST wrap the chain as much as you can, like up to 180° so it won't hop a tooth.

Had power drive and didn't like it with my limited 18hp.

[Crusarius]

I thought about adding power feed but I don't think I ever will. I like being able to feel the cut, that way I can adjust speed accordingly.

I would not go nay less than 1" acme rod. Will smaller work? Yes. but for longevity I would lean tow3ards the 1" with a large brass nut.

the looseness of the tube in tube is not a concern at all. once you start cutting the sawhead is pushed against the mast and keeps the head from moving. if the sawhead is not against the mast you are not feeding fast enough.

I bought my acme rods from Linn Lumber. they were already machined for pillowblock bearings on both ends and key slots on one end. I just used a #40 sprocket with key and I needed to do almost a full 180 degree wrap to prevent chain skipping.

I am still not sold on the acme rods for lift. But they do work. I would love to find a way to make the lift faster but the down is perfect speed.

[JRWoodchuck]

I think my acme rods 1" and have had no issues in 6 years other than lift speed as well. I had mine machined down to 3/4"on each end for a pillow lock bearing at the top and it seems like a trailer axle bearing at the bottom. The top was also machined down the rod further to make room for sprockets as well. On the tube in tube the longer you make your sliding body the less bind there will be even if the head is unbalanced. I think mine are 14" ish long. 

[rusticretreater]

My Woodland Mills saw uses HDPE(cutting board plastic) to control the freeplay of the tube inside of tube design.  Flanges are needed to hold the bushings in place.  The beauty of the design is that they are adjustable. 

It also has a really nifty dual cable lifting system. There is an acme screw inside the cranking mechanism.  It doesn't take much effort to raise and lower the mill head.

Hope this gives you a few ideas.




 

 

 

 

[Crusarius]

What I wouldn't have given to see that routing a long time ago when I was playing with different lift setups. Better late than never  Thanks rustic.

[Brackish]

Ok
I still plan to continue my mill build but...
For less the the cost of my list of materials I purchased a used Hudson mill from a local guy that was nice enough to deliver set up demonstrate and give me several hours of training and questions and answers. 
It is much less capable than the mill I want to build but I'm sure this will be beneficial to my design ideas as well as get me milling. 

I cut my first boards yesterday.

I am considering ordering the stock and start with the frame for the track for the mill I want to build. I think I could use the frame as a platform for the hudson mill I bought as I don't want to be trying to keep the track level on the ground. 

[fluidpowerpro]

That's a great plan. By using the first mill you will learn what you want on the one you build.