Sawmill Build - Chain Slabber & 90deg Circle on the same tracks

[bandmiller2]

Pitot,your a man of action.I like the log dog setup adjustable and self locking.Do you have any provisions for toeboards to compensate for log taper??Only thing I can see is there is a minimum distance for twisted "V" belts ,too close and the belt life is dismal.Its hard to beat a well equipt warm shop.I'am sure if something isn't just right with your mill it will be redesigned post hast.Frank C.

[DanG]

The design looks good to me, in that it looks a lot like the MD design.  The one thing that concerns me is the bearing in the back-end of the engine with all that lateral pressure on the crankshaft.  You seem to be familiar with the MD and you probably know that they modify their VW engines to put a big honkin' bearing there.  Of course, it is a two piece case rather than a solid block, and that may make the difference.  I would check on it before I put much money and effort into it, though.

[pitotshock]

Do you have any provisions for toeboards to compensate for log taper??

Nothing in there yet, but I want to start out simple and expand as time goes on. My plan was just to have some 2x6's handy to adjust for taper if required. I do have a little 2 ton bottle jack sittin around though...

The one thing that concerns me is the bearing in the back-end of the engine with all that lateral pressure on the crankshaft.  You seem to be familiar with the MD and you probably know that they modify their VW engines to put a big honkin' bearing there.  

Actually I have only seen the MD through this website and photos online, so I am making a lot of guesses here. Thanks for the heads up on the VW bearing upgrade they did. The rear end bearing in an auto engine is certainly not designed for this kind of abuse. Your right in that lateral load problem and I was trying to wrap my head around adding in some bearings to support the output pulley, but nothing has popped in there yet.

What is the rough distance between shafts on the MD that the twist belt runs between? (just to give me an idea of size) As my mill is pretty small, I want to keep things fairly tight together to give the most adjustment range possible.

[Hilltop366]

Great drawings, this is very much what I was looking to do, I have a larger engine from a toyota 2200 cc Camry that I was wondering if it could be used, it makes it's power at a lower rpm. I was thinking about the stress on the rear bearing and figured it would require some sort of extra bearing(s) and mount before the pulley, it's still in the car so I am not sure what the end of the crank shaft looks like but I don't think it will be the right shape to mount a pulley directly to. I have a plate or frame sort of thing in mind  that bolts to the engine once the trans is removed with a heavy steel tube turned on the inside for bearings and internal snap rings and a shaft made to except the engine crankshaft on one side and pulley on the other.

Was also wondering if the front of the engine would be better equipped to handle the side load of a belt, it already has belts on it so I was fiquring a load in the other direction would reduce the side load or at least make it down instead of up. It might be eaiser to make a adapter to the crank pulley than the other end of the engine. A side benfit is the vert. blade shaft could be much shorter.

I was wondering if it would be better to make enclosed bearing holders with two bearings on each end for the blade shafts and put it through a piece of rectangular tubing, cut the tubing off at a angle to expose the inside to provide a place to put the bolts to mount it. I know this won't be cheap but if you add up the cost of good pillow blocks (you have 5 and I think the ones next to the blade should be doubbled for a total of 7 imo) it adds up quick.

May be some thing like this or move the main shaft to the right and reverse the position of the pulleys on it.(main pulley in center and second shaft pulley on end)

More things to ponder.

[DanG]

Pitot, I can see that you have some challenges ahead of you with that narrow chassis for this type of mill.  That factor alone may restrict you to a vertical shaft, now that I think about it.  The crossbeams on my MD are 8' wide, and I'm still restricted to about a 36" log, due to the width of the power/saw head.  It looks to me like you're going to have to cantilever the engine out to one side in order to save that width for the log.  One thing I've thought of is to use a chain like a motorcycle to transfer the power to a jackshaft, to take the strain off the rear bearing.  You could run a shaft with a pair of U-joints to a jackshaft, but that would eat up a lot of width too.

On the MD, there is an 8 groove pulley on the extended engine shaft.  Six of these grooves are for the shaft of the main saw, one for the hydrostatic drive, and one for the alternator and governor.  The main saw shaft has two six groove pulleys, and the edger(s) runs off of one of them.  Those pulleys run between a pair of pillow block bearings.

I really think you would profit by seeking out a MD, Mighty Mite, or D&L mill to saw on and study.  A lot of this wheel has already been invented.

[pineywoods]

Just some comments on adapting automotive engines. Very similiar to the problems encountered when using an automotive powerplants in aircraft. Keep in mind that those crankshafts are cast, they crack and break easily when subjected to un-intended side loads. forged steel cranks are a real good idea. The neatest conversion I have ever seen was thunk up by a guy named Steve Whittman of air racing fame. A foot long piece of the outboard end of a chevy truck axle, the outside face machined off flat and holes drilled to mount in the place of the flywheel. Think big metal flower pot the size of the bell housing with a good sized hole in the bottom, and a flange around the top. Bolt that on to the bell housing mounts, with the stub axle sticking out through the hole in the bottom. Then mount a big honkin sealed double row ball bearing in the hole in the bottom of the flower pot. Also gets the engine out of the way of whatever you are powering.. Cheap and simple, but rugged, the kind of thing Steve was famous for.

[Hilltop366]

Good point DanG about the width perhaps if the engine was raised up and the blades more centered under the engine the engine could hang over the track on either side when at the outer most position this way it would not be too out of balance, the balance is something I didn't consider when making my CSM and had to add out riggers on the engine side (and yes I have tripped over them a few times).

Pineywoods what your talking about for a output shaft is more or less what I had in mind except I was thinking about using inner and outer bearings to eliminate side load, I guess it is a little different than spinning a prop, where the belts are putting pressure on one side.

Another mill to look at that Meadows Miller put me on to is the Rimu.

[pitotshock]

OK, more food for thought.

Keep in mind that those crankshafts are cast, they crack and break easily when subjected to un-intended side loads. forged steel cranks are a real good idea.

My intention is to have a fairly small sawmill and only using ~30hp from the suzuki engine (say 3300 RPM instead of Max hp at 5500 RPM). So I would not expect loadings to be excessively high. I am trying to mentally compare the design of the crankshaft and bearings from a Kohler Twin 30hp engine against the Suzuki Swift engine and I would have to say that the auto engine is a lot beefier. Surely if the Kohler/Briggs etc crank can be side loaded to this degree, the auto derivative can be?

This is the insides of a Kohler twin



The suzuki 3cyl engine block and crankshaft bearings. (Design as expected)





Below is the Suzuki Swift engine being used for the power source in ultralight aircraft. You can see that these use a cogged belt to reduce the rotational speed for the prop. These engines are developing somewhere around 60hp and you can see both the supported and unsupported versions. The unsupported setup will put side loading on the engine bearing to the same degree as the this would



The unsupported belt drive - pulley attached directly to flywheel


Bearing supported pulley drive



For their lowest output engines they use the unsupported version. When the engine power is increased they switch over to the supported type.

[pitotshock]

Ok here is the circular blade superimposed on my small mill tracks. This shows the two extreme positions and the engine position.





Looks a little tippy when cantilevered out that far. But you could put the battery and fuel tank on the opposite side to balance it out a bit. The engine itself is only 140lbs; put some blades, bearings, pulleys etc and you are up over 200+lbs. You can see why I ran the pulleys off of the flywheel and put the blade in the front. Trying to compact this design as much as possible.

Need to go really high on the frame to get over the top of the engine to put cross bracing in place on the right hand side

[Fla._Deadheader]

What type pilot bearing is in the end of the crank ???  If It's a bushing, what about a plate that attaches to the bell housing holes, with a Flange bearing that just might fit inside the space created by the crank case, or, reverse the bearing to the outside of the plate. I'm referring to some engines that have the flange for the Flywheel recessed as it were, inside the plane of the block.

  Put the pulley on the shaft that will be run through the flange bearing and into the crank. Shaft would have a collar welded on to bolt to the crank flange. Put the pulley outboard of the bearing ???

  That would reduce the side load a bunch, and have a greasable bearing as well ??? 

  We did something similar on the Porsche engine we first had on Homey.

[Hilltop366]

Yep I see your point about the compactness it probably don't get any better than what you have drawn.
It may be that the easiest way to cure the overhang problem is to make wider tracks.

[Don_Papenburg]

Insted  of a twisted belt in the short distance ,why not a 90* gear box?  Surplus Center has a few.

[pitotshock]

Insted  of a twisted belt in the short distance ,why not a 90* gear box? 

Yes I think a 90* gearbox would work very well to power the edger shaft. But, in general I am keeping this build as cheap as I possibly can (just for fun, really). If I was forking out the cash for a 90* gearbox I would probably go towards a swing mill design. Those mills are such and interesting concept that works very well on the manual machines.

[pitotshock]

Found a company website that does commercially built chainsaw mills, thought I would share the link with everyone who may not have seen them yet

http://www.lmsaws.com/chainsawlog.htm


Side note, my 4 stroke chainsaw mill is progressing well, but I am now into fabricating all the small parts. So a lot of work is goes into a handful of parts. This follows the 80/20 rule, I am spending 80% of my time on 20% of the machine.

Once I get the thing put together more pics will come.

[fishpharmer]

Thanks, Pitotshock, neat link. Although I believe Tom shared that previously, looks familiar, not sure. 

I look forward to your results.

[pitotshock]

Here are a couple of updates.

On the chainsaw slabber, I have the drive shaft completed and tensioner pulley installed. Just waiting on my 1/2-10 ACME tap to arrive in the mail so I can cut the nylon nuts and install all of the raise/lower mechanisms into their final place.





Further design and development on phase 2 (90 deg circular saw) is going well. While the small car engine was a good distraction it is not going to be part of the immediate build as it was going to add too much complexity for this build at this time. Maybe it will become a phase 3. Besides couldn't find the engine I wanted for free as of yet...

So here is the updated design with the 18" diameter blade turned up onto the vertical to improve the deeper cuts and the space between the two shafts made as great as possible to give the 90 degree twist belt a chance. This design built around my existing tracks will allow up to a ~30" diameter 16' long log to be sawn. Big enough for me.





I also pulled the 17hp vertical shaft Briggs Intek engine for phase 2 out of the lawn mower last night.

[Hilltop366]

Nice to see you are making some progress. On the csm I was wondering if you have a way to adjust the blade or saw carriage (front to back and side to side) so it is running on the same plane as the log bunks. I used a long straight edge set across the saw bar at 90° and measure down to a bunk on each side of the bar. Looking forward to the first test run!

Cheers

[pitotshock]

Adjusting the chainsaw bar to be parallel to the bed is done with each of the four acme screws on the frame. Each threaded rod is 10 threads per inch with a 16 tooth chain sprocket on the top. So, rotating one of the rods by one tooth on the sprocket will get an adjustment in that corner of 0.100"/16= 0.006". Kind of overkill for this application, but you will be able to true the blade in both front/back and left/right directions.

[Hilltop366]

That should do the trick.

[pitotshock]

OK, so my 1/2-10 ACME tap arrived and I cut the nylon nuts that ride on the 4 ACME threaded rods. The blocks are machined to a snug fit inside the ends of the frame.

Like So







Then the four screws are activated with one hand crank by a 35 series roller chain. The ACME rod has 10 threads per inch, the sprocket welded on those have 16 teeth and the hand crank has a 40 tooth sprocket. That makes the hand crank move the bar 1/4" per revolution.








All the forces side to side or front to back are transmitted through the split linear bearings, which were machined from blocks of nylon. These forces are taken into the cart by 1" cold rolled round bar. I really wanted chromed bar, for corrosion and wear, but was not to be had for cheap.





Here is a pic from below of the belt drive and the electric clutch. Note that I completely screwed up the tensioner pulley as it is on the wrong side! It will have to be moved over the the opposite side to work properly. Don't know what I was thinking that day...





Next up is mounting the fuel tank, battery, bar oil tank and a panel for the engine.

[Hilltop366]

Looks good, next thing you know you will be cutting some wood!

Looks like the tensioner pulley is a V type, if so I would suggest switching to a flat pulley and put it on the outside of the belt that way it will put more belt on the driven pulley for added traction,it will need it, if not never mind.

A source of cheap chrome rod is old car struts and shocks (might not be long enough for this) Your not the only cheap assed on here  :D

[pitotshock]

My original idea for the chromed bar was to use the front forks from a motorcycle and just take out the inner tube. Large diameter and plenty long enough. The only thing is you would need 4 for this design and that means 2 bikes with the same front forks. If I ever upgrade this setup I might do that. There is a bike wrecking yard not too far from here, that you can pick through and find the stuff you need.

[Hilltop366]

Bike forks! , man never thought of that, good one.

[pitotshock]

OK guys,

here is the latest update. Things are progressing well; got the tanks in place, wiring and control panel built. Got engine started and running (to test the wiring). Disassemble, paint and reassemble. The paint is a two part urethane industrial coat that was on special at the local auto supply place.

This is the assembled saw, just a few pieces to go now






The 1/4" polycarbonate shield for protecting against the rotating bits


The control panel

[pitotshock]

Well I got the last components put on the machine, namely the chain oil system which consists of a 12VDC solenoid valve and a brass needle valve. This is only switched on when the electric clutch is engaged, so no oil is being wasted




Made up my chain (.404 / 0.080) and installed it





Fired up the engine and engaged the chain. Started turning and the clutch seemed to fail. Made a whining noise for about a second and came to a stop. When you turn the belt by hand the clutch just has a grinding feel to it. I think it's cooked. Will have to disassemble and take this one apart.

Just figures, when everything is ready, one of the most expensive pieces breaks...