Need advise on my sawmill project

[Ken Malone]

Has anybody tried to run a saw with a 12 hp ride on mower engine and trans.?Thanks

[NewYankeeSawmill]

Mine has an 18hp Briggs and Stratton, and it struggles with some of the harder wood types. I imagine you _could_ run one, but it might take some time depending on the wood.

[Jeff]

I think some of the entry level hobbiest saws have as small as 5. What that harbor fright saw have? 

[fluidpowerpro]

The first saw I had used a 6.5 HP engine. It cut up to 18" wide. It worked fine but slow.
I think you could make 12 HP work. Assuming your using the transmission because it's a vertical shaft engine? If you use the transmission the output rpm will be really slow so you will need a huge pulley on it. You will also lose some efficiency through the transmission so I would avoid using it. Get a 90 degree gearbox instead.
At the end of the day you will be much better off using a horizontal shaft engine 

[Old Greenhorn]

The engine size will get you in the game, but that transaxle will give you nothing but grief between efficiency losses and speed. If you don't have a horizontal shaft do what FPP suggests above. The transaxle will be nothing but a time suck and disappointment.

[SawyerTed]

There are considerations regarding blade speed and cutting speed relative to hp.  

Tim Cook, Cook's Sawmill, has a good article on hp and blade speed.  A internet search will find it, I can't post the link for some reason.  

The blade speeds needed don't lend themselves to the use of the transaxle.  A gear box ($$$) can be used but there's a reason manufacturers don't.  

In the long run a horizontal engine will be the best approach.   More hp means more blade speed and more hp means more torque.  More torque means less blade speed drop which means consistency higher cutting speeds. 

[RetiredTech]

 Having worked on a lawnmower transmission or two I have to agree with the advice already given. Ditch the transmission. It's designed for low speed use. The axle is probably 3/4" - 1" which is pretty small for sawmill use. Then there's the differential to deal with and the axle bearings on some are just bored through the cast aluminum casing. It's not a question of if it will fail, but when.
 As for the motor it should work. If it's vertical shaft, I saw one DIY mill article that used a drive belt with a twist to a horizontal shaft. It seemed to work for him. I don't remember if it was in the forum or on YT. Blade speed can be adjusted by pulley size.

[ladylake]

 You should be able to find around a 20 hp horizontal shaft motor cheap.  Steve

[Ken Malone]

Ditching the ride on motor and transmission idea.Thanks for the info. I'll find a horizontal shaft motor and go from there.Thanks Ken

[Ken Malone]

I'm planning to use 2 pieces of acme rod to raise and lower my cutting head.will be a Manuel crank setup to start maybe power later on.Any suggestions on setup? sprocket sizes? Shaft orientation? Should I have 4 posts or 2. I thought 4 but I'm having trouble with it jamming.is balance an issue with 2 posts?

[jpassardi]

Have you considered a chain and sprocket or a cable lift setup? The acme rods will be slow/take many turns.

[Ken Malone]

I thought the acme rods would be more acurate.
Read that somewhere.speed is not really an issue for me.later I may add a 12v motor.

[beenthere]

It's a sawmill and the accuracy of a chain is more than enough. Should be no variation along the cut, if the slack is taken out of the chain (or whatever system is used) when moved to the next position. Dropping the head down to the next set is something that has to be taken into account. Coming up not so much.

[Ljohnsaw]

The nice thing about ACME threaded rods is it is self locking. With a chain lift you will have to deal with locking. If it is a cog like latch that it is fine enough that you can hit your desired height mark.

[mike dee]

I picked up a new 2,000lbs electric winch for $49 during covid and used it to drive a chain connected to a sprocket on the manual crank that raises and lowers my cutting head. The winch uses planetary gears and doesn't drift. Being a cheap winch it goes slow and ended up being about the same speed as hand cranking it. I use the winch remote to power up and down.

Goes all day on an old car battery that lost it's oomf to crank a car.

[Mooseherder]

I have tractor trailer landing gear on my homemade mill that my friend built.  A 12 volt electric motor moves it up and down okay.  A logger whiplashed the mill head unloading logs a couple of years ago and snapped the right side rod.  It's welded up and working but not good as new . These type gear boxes are two speed. Granny and fast granny.

https://www.truckspring.com/heavy-duty-truck-parts/trailer-landing-gear.aspx

[Ken Malone]

 I like that set up.Thanks for the pictures.you got me thinking.

[Nebraska]

url=https://forestryforum.com/gallery/displayimage.php?pid=356810][/url]

Chain lift set up on my old Timberking B16

Actually it's pre Timber King was a Belsaw product. But it is pretty accurate and the gearbox does hold its place fine. 

[Ken Malone]

  another good idea!

[jpassardi]

Another option is a dump truck tarp gearmotor - works well for me, powered through a cheap PWM controller for variable speed.

[Ken Malone]

Ya! And I know where I can get one.Thanks

[jpassardi]

You're welcome. Be sure to use a PWM controller so you can creep up on your cut height.

[moosehunter]

Ken, 
 I see that you have posted two different threads re your sawmill build. I would like to suggest that you just have one thread. Ask all of your questions on it and have all of your responses in one place.
We like following along with new builds.
Good luck!
mh

[RetiredTech]

While trying to find the sawmill build I remember seeing with a verticle shaft motor I ran across this one, and right in this forum too. It's not the one I was looking for, but it's a unique build to say the least.
Lawnmower Engine Powered Bandmill (sawmill)
It just shows what you can do with what's on hand if you put your mind to it.
Here's one picture from his gallery.

[Ken Malone]

Now the question,should bed travel on 4 posts or 2. I have started with 4 but seems to be binding a fair bit. I thought that 4 posts would be more balanced once motor and other gear is mounted.Should I rethink this? Thanks Ken

[fluidpowerpro]

My experience has been that 4 posts is much better than 2. When I say 4 posts, its 4 posts to support the whole carriage plus 2 posts that the saw head rides up an down on. This is like whats done on the Hud-son Oscar series of saws. 

[Ljohnsaw]

I have 4 posts and 4 ACME screws. I made some brackets that wrap 3/4 of the way around the uprights. I tucked in some 1/2" thick blocks of UHMW plastic for a low friction fit. It's definitely not a precision fit. IMO, it is fine to wobble about. It's the height that is critical that it be robust.

You can see one behind my scale.

The scale is magnetically stuck to the post with a toggle clamp at the bottom.

[Ken Malone]

How do I add a photo?

[Magicman]

Look at the last item on the Index Page:  How to Post Photos.

[esteadle]

l22

[fluidpowerpro]

I like the 1 HP per tooth in the wood analogy but I think you really need to define cutting speed along with it. 
I have cut a 36" red oak log with my 16 HP mill at an "ok" speed but would love more HP to go faster.
What I think is "ok" I'm sure would be unacceptable to others.
It would be interesting to know what manufacturers use to estimate cutting speed per HP, cutting width, species and blade characteristics. 
I know there are more variables but those are probably the biggies.

[jpassardi]

My personal experience: I upgraded from a Kohler 15 HP to a Kohler 25 HP. I forget the exact numbers but it was about a 40% increase in torque. It cut like a different mill right away, especially in wide cuts. I can now feed quick enough that I'm not making fine powder sawdust on wider hardwood cuts.

[Ken Malone]

I got some 1" 6 tpi acme rod but having a hard time finding nuts for it. any suggestions? I'm in Nova Scotia and there are very few options locally.moose herder id like to see more picks of your complete acme set up if I could.Thanks.oh I scrolled back and see all your pictures.

[Mooseherder]

Here is how mine is attached on both sides with steel plate. 

[fluidpowerpro]

I was going to suggest Surplus Center but they only show 7/8 -6 . Are you sure it's 1"?

[beenthere]

A reasonably good, competent machinist can make the "nut" for your threaded rod.

Have you looked at McMaster-Carr for what they might have?
https://www.mcmaster.com/products/nuts/lead-screws-and-nuts~/acme-lead-screws-and-nuts/?s=acme+nuts

[ladylake]

I got some 1" 6 tpi acme rod but having a hard time finding nuts for it. any suggestions?

Try Roton, they have  all sizes at good prices.  You want to use a bronze acme nut, last way longer.  Steve

[Ken Malone]

Ordered bronze nuts from Roton. Thanks everybody for sugestions. This is the best source for info .I have found. Great to get advice from people who know what there talking about.

[Ken Malone]

Do I need a centrifugal clutch on the motor to drive wheel or just an adjustable idler pulley to engage blade

[jpassardi]

A lever engaged idler pulley is less expensive and less prone to wear out but either will work.

[Ken Malone]

Going with idler pully. Thanks

[Ken Malone]

Any suggestions to pull y ratio and motor size to run acme rods up and down. Using 6 tpi 1" acme.

[Ljohnsaw]

A lot of trial and error for the sprocket sizes. Mine is dual speed via a 12/24 VDC switching. Since you are using 6tpi, I would make a guess that you will probably want to raise at 1"/second at the fastest. So the ACME rod will need to spin about 360 rpm for quick moves and be able to slow down to half that to hit your mark via voltage or a PWM controller.

I have tiny (12 tooth?) sprockets on the rods all connected in a loop. Then a larger sprocket on two on the left side. A smaller loop of chain hooks those to the wheelchair motor. I changed the sprocket on the motor a couple times until I liked the speed and power.

Here is an early picture of the setup with just one rod connected to the motor.

The big sprocket got moved to the motor and replaced with a slightly smaller one.,

[ladylake]

 My mill uses a 1/2 hp 56c motor mounted to a 5 to 1 right angle gearbox with about a 6" no 40 sprocket driving 1 1'4 5 tooth per inch acme screws. The sprockets on the screws are the same size as the gearbox sprocket.  That works out to about 350 RPM on the acme screw. Mine is 5 tpi with  6 tp I'd shoot for 400 RPM Steve 

[Ken Malone]

Now on to idler to engage the drive wheel. Any suggestions and picks would be much appreciated.

[Mooseherder]

Mine is direct drive unfortunately.  I've got my mill tarped up for winter now. We got about 8 inches of snow for Thanksgiving.

[Ken Malone]

No snow yet here in Nova Scotia but she's a comin

[Hilltop366]

I can wait a little longer (a lot longer really) for snow here on the Southwest end of NS, what area are you in Ken?

I wonder how well a riding mower transaxle would hold up as they are not made to use most of the power the engine produces as most of the power is required for the blades, the drive belt is often the weak link but some models are more prone shaping axles or breaking teeth off a trans gear then the gear tooth lays over and jambs in the next go round and forces the case apart. Generally a yard and garden tractor have much tougher transaxles than a riding mower.

[Ken Malone]

Hey hilltop Ken here in upper nine mile river.

I picked up a 14 1/2 briggs horizontal shaft and going to run mill with belt and manual idler pulley.
Just about ready to give her a try.

[Ken Malone]

Is a compression spring needed on the blade tensioner? I was told it is a must but I'm not sure.

[jpassardi]

You really should have a spring: air bag, coil or rubber. The problem with not running one is that as the band expands with temperature it grows in length and tension is lost. The spring maintains band tension. The wheel belts provide a minimal amount of "cushion".

[ladylake]

 Yes put a spring tensioner on your mill.  Steve

[Ken Malone]

I picked up a 1/4 hp gear motor that is rated at 18 rpm ratio 95:1 does this mean the shaft turns 1710 rpm? It is rated at 750 in lbs torque I'm hoping to raise and lower mill with it.Any thoughts?

[Ken Malone]

I have a 18 rpm dc gear motor.when I power it up with a car battery I get about 3 rpm.Any thoughts? It also says 90 v on the tag . What does this mean?

[Hilltop366]

I would think v=volts which would explain the low rpm at 12v.

[Ken Malone]

Do you mean it would take 90 v to get the 18 rpm?

[Hilltop366]

I think so.

It was likely made to run with a controller that converted 120 AC to 90 DC. 

[Ken Malone]

Yup your right.came off a treadmill.

[Ken Malone]

I'm now on to building blade guides. I've seen many different configurations  just wondering what is the best.Any ideas or pictures would be great. Thanks Ken

[Ljohnsaw]

Ken, Do yourself a HUGE favor and just buy the Cook's roller guides. That's what I finally did after having regular bearings lockup at least once a year.

I made my own drilled mounting bolts with a zerk fittings to grease them. That was mounted on a rod that fits in a square 2"X1/4" wall tube. Two bolts per side allow for full adjustability.

In retrospect, I should have just used a piece of solid square stock instead of the round, it would have been easier to fab.

This was after rusting all winter.


This also shows the supports for the adjustable arm.


The whole boring build thread

[jpassardi]

I agree with John, you can get the assemblies from them with adjusters and save some fab time.
I also suggest their felt/diesel dripper if you plan to mill pine. I retrofitted one to my Woodmizer. Buying the parts separately is nearly the same cost.

[Mooseherder]

I have a 18 rpm dc gear motor.when I power it up with a car battery I get about 3 rpm.Any thoughts? It also says 90 v on the tag . What does this mean?

This is the Dayton Gear motor on my mill for forward and back.

[fluidpowerpro]

I would say the 90v is the intended operating voltage.

[Ken Malone]

Just installed a new centrifugal clutch but it doesn't disengage . It turns at idle speed. Any thoughts? Thanks Ken

[fluidpowerpro]

When I first got my saw the idle speed was set too high so the clutch didnt disengage. Whats your idle speed set at? Try bumping it down a bit?

[Ken Malone]

My idle speed is 1700 rpm. The clutch is not supposed to engage until 2000 rpm.

[Ljohnsaw]

That's a pretty high idle. I like it down below 1,000. I think mine is around 7 or 800.

[Ken Malone]

What do you have for an engine? I don't think mine will run that slow without quitting. Thanks Ken

[fluidpowerpro]

1700 sounds high to me also. Mine is at about 1000. It's a Briggs 16 HP Vanguard.

[fluidpowerpro]

Was just thinking...
If it engages at 2000 it might need to drop below 1700 to disengage. Everything has a dead band and for a mechanical device like a clutch 300 might be too close. On mine I noticed that when getting close to engaging or disengaging, it makes sort of a clanking noise.

[Ken Malone]

Ran it full throttle for about 2 min. Now it's working fine😁

[Ken Malone]

Just wondering what the blade tension should be and how to gauge it .Thanks

[barbender]

There was a thread on here about a poor man's strain guage a long time ago. Two clamps and a dial caliper. Open the caliper up an inch or two, clamp the jaws to your blade. Zero the caliper out. Now tension your blade, and watch the reading on your caliper as you tighten. The problem is first- I never did this, just read about it; and second, I don't remember how to convert the measurements into psi of strain. Obviously this would be onerous to do every time you put a blade on, so you would figure out a method to correlate the adjustment on your tensioning device with the corresponding correct strain. Clear as mud?😊

[Ben Cut-wright]

The dial caliper method of strain measurement works quite well. I've used it on many (same size blades) and compared the measurement with a dedicated strain gauge.  They are close and often identical.  Conversion charts are available online.  It's not necessary to measure every blade, IMO.  Note the position of the tension mechanism for the representative blades and adjust to that set point when replacing same-blades.