# Slab Mill



## bradleywellsoff

Check this mill out. Just getting into milling. All I've really been doing is slabbing, and getting tired of the chainsaw. Seems like this would be a little easier to build than a band saw mill. Has anyone had any exp. with one of these?
http://www.youtube.com/watch?v=r2SaQu-t8aM


----------



## mics_54

hmmm
It is a chainsaw. Except this one has probably got all the disadvantages of a regular chain mill with a few more added to boot. Longer chain. Longer bar. What were the advantages you were thinking?


----------



## bradleywellsoff

MICS 54,
Has a more powerful power head. Looks like it could be 10-12 hp. I see the longer bar and chain as an advantage to cut larger material. Looks more stable and alot easier on the back than the alaskan mill that I am currently running. The Alaskan Mill is nice, but requires a straight edge for the first cut, then an adjustment to the mill with a knuckle busting wrench for additional cuts. Being on a budget, (like most) could be built with alot less $$$ than a band saw mill. Just a few of the advantages I was thinking of. Looking to purchase or build my first mill. Width capacity and cost are major factors.
Any advice would be helpful.
Thanks, Brad


----------



## TexasTimbers

It's a nice slabber. Made by Peterson in new Zealand. They make swing mills. I plan to get one of their swing mills whenever the wife turns her head long enough. 

I'd love to have that slabber for a weekend. Have about 20 crotches I'd like to take apart. Some too big even for that slabber.


----------



## Daren

TexasTimbers said:


> I'd love to have that slabber for a weekend. .


:yes:. There is not even anyone close to me with a Peterson or Lucas swing mill, Id'a hired/helped them on a few. I too have almost pulled trigger on a swinger with the slabbing attachment more than once over the years. But they really shine on LARGE logs. For small-medium logs you just can't beat a bandmill. I have had opportunities to slab out big logs (and crotches) 60"-70"...100" across, but not the equipment. The thing about those swingers is you don't have to move the biggies, set the mill over it and saw away. But they are expensive :whistling2:. Having said that so is a hardwood slab 4'-6' wide . _IF_ I had access to the big ones all the time I would have a swing mill also no question.


----------



## dirtclod

I've been wanting a slabber (or the use of one) to break down some large logs. Even considered building one on tracks. But it's just thinking. 

Like TT, doing some big crotches would be handy. I have some 3-5' diameter trees to do. Too big for the mill. Can't even budge them from where we'll drop them. So breaking them down into quarters will make them easier to move to the mill for even easier board making. We'll be in quarter-sawn heaven. And dreaming of some 4-5' wide slabs 20' long.

Here's a 5' dbh red oak we were given 3 years ago. I just noticed how big that crotch looked (7' across?) a couple weeks ago. It's still waiting for a plan. 









I don't know about Peterson specifically, but I've seen some that offer several different engine options. You've got to admit. 4-stroke engines are not as loud as 2-stroke.


----------



## slabmaster

I've thought of using 4-stroke engines for milling, but they just don't have the rpms to drive a milling chain with speed.And if you gear them for speed , you lose too much power.So for a bar&chain mill, i would use a big 2 stroke engine.Just no way around the rpm/weight advantage of a 2-stroke engine.


----------



## TexasTimbers

slabmaster, I have been "dreaming" with a couple of other dudes on other forums about building a 4 stroke slabber. I have all the parts necessary to do it including an 18HP Briggs. 

The thing about the 4 stroke that we believe is, with enough horses you don't need RPM's. There are 3 rules when using 4-strokers you need to remember:

I. Torque is King. 
II. Torque is King.
III. Torque is King.


----------



## Daren

TexasTimbers said:


> I. Torque is King.
> II. Torque is King.
> III. Torque is King.


Just like drag racing...:yes: RPM is nothing if you cannot put it to _work_.


----------



## dirtclod

I may not know enough about these conversions and fall flat on my calculations. But here's the little I understand and the results of my calculations when comparing a Husky 575 XP chainsaw engine to Briggs 18 hp engine.

Briggs 18 hp verticle shaft Vanguard: torque = ~35 ft.lbs. @ 3600 rpm. Source = http://www.jimsrepairjimstractors.com/torque-specs.htm

Husky 575 XP chainsaw: 5.8 hp @ 9000 rpm. Source = http://www.usa.husqvarna.com/node3100.aspx

I couldn't find Husky's torque ratings. So using the formula hp = torque x rpm / 5252 I should be able to figure it out since Husky did show the rpm rating at max hp.

5.8 x 5252 / 9000 = 3.3846222222222222222222222222222 or around 3.4 ft.lbs.

As I understand it, when a given amount of horsepower is put into a gearbox the same amount will come out, less any friction. So the main change through the gearbox will be torque and rpm.

Assuming you wanted to compare both engines using the same sized sprocket/bar combo at the business end, then you need a gearbox ratio to convert the Briggs' 3600 rpm to the Husky's 9000 rpm.

9000 / 3600 = 2.5

So the Briggs' 18 hp with 35 ft.lbs. @ 3600 gets converted to 18 hp with 14 ft.lbs. @ 9000 rpm after going through the gearbox. (35 / 2.5 = 14 and 3600 x 2.5 = 9000.) This still doesn't include any frictional losses in the gearbox...but they should be minor.

So the results of the comparision of the Husky being used as-is -vs- the Briggs going through a gearbox is:

Husky = 5.8 hp and 3.4 ft.lbs @ 9000 rpm
Briggs w/gearbox = 18 hp and 14 ft.lbs. @ 9000 rpm *

* does not include gearbox frictional losses.

That was fun! But now my head hurts.:laughing:

Does it look right to you?


----------



## Daren

dirtclod said:


> Does it look right to you?


If you say so :laughing:. The math I think about in these type of situations is length of service. A Briggs (or Honda or Kohler or...) at 3500 rpm will run for years, decades. Change the oil and feed it gas. A 2 stroke engine by it's very design (no oil bath, the oil is mixed with the fuel) simply will not last as long as a 4 stroke I don't care what anyone says.

There is the weight to power ratio advantage a 2 stroke has. But we are talking mounted on a mill head here not carrying it around in the woods. A 4 stroke hand held chainsaw would be impractical.

Mixing (and burning) oil the whole time does add to the cost of operation. They are noisy (2 stroke) my little 13 HP Honda purrs like a kitten, I sawmill in the middle of town-no complaints.


----------



## dirtclod

One error I spotted was I took the wrong torque rating from the Briggs chart. Here's what it should be:

Briggs 18 hp verticle shaft Vanguard: torque = ~25.25 ft.lbs. @ 3600 rpm.

So the Briggs' 18 hp with 25.25 ft.lbs. @ 3600 gets converted to 18 hp with 10.2 ft.lbs. @ 9000 rpm after going through the gearbox. (25.25 / 2.5 = 10.1 and 3600 x 2.5 = 9000.)

And the final output ratings end up:

Husky = 5.8 hp and 3.4 ft.lbs @ 9000 rpm
Briggs w/gearbox = 18 hp and 10.1 ft.lbs. @ 9000 rpm *

* does not include gearbox frictional losses.

Even using the proper torque rating I'm still not able to get the output of the gearbox to equal 18 hp when taking the calculated torque and rpm output through the horsepower formula. But it's close at 17.3 hp. Close enough for me.

Hey I couldn't agree more Daren...definately the lesser of two evils.


----------



## TexasTimbers

clod that was some fancy calculatin. I am seasick now though and the room is spinning. :wacko:


----------



## dirtclod

Ok, ok!. I see the little error that kept it from perfectly balancing. The torque on the Briggs from the chart s.b. 26.26 not 25.25. So the final results should be:

Briggs w/gearbox = 18 hp and 10.504 ft.lbs. @ 9000 rpm

That's ~ 3 times the hp and torque of the Husky. I'd say she'll do a good job.


----------



## TexasTimbers

So I guess torque is king after all. :gunsmilie:


----------



## bradleywellsoff

I would most likely use a 15 - 20 hp vertical shaft engine. There dosent look to be a gearbox on the mill in the vid. Looks like an extention off of the shaft to a clutch and sprocket assembly. Not a real good shot of that area though. Where could I source a gear box? Mabey an rideing mower trans? I could have a 5 speed slab mill!:brows: Some type of direct drive system would be alot less complicated to set up.


----------



## dirtclod

A right-angle gearbox for a horizontal shaft engine. Or for a verticle-shaft engine, an in-line gearbox, or two different sized pulleys/cogs and a V-belt/chain... There's more than one way to skin a cat. Just watch which way you point that exhaust. 

I wouldn't use the clutch from a standard chainsaw head - too whimpy. Get a heavier clutch like's used on bandsaw mills. 

I'm liking the verticle shaft engine and two pulleys and a v-belt. There's more than enough power left over to overcome the power loss of a v-belt. The parts are less expensive and easier to get.


----------



## TexasTimbers

dirtclod said:


> I'm liking the verticle shaft engine and two pulleys and a v-belt. There's more than enough power left over to overcome the power loss of a v-belt. The parts are less expensive and easier to get.


Great minds ....... because that's exactly what we decided some nearly 3 years ago. I am not running behind schedule. I never do. :yes:


----------



## bradleywellsoff

dirtclod said:


> I'm liking the verticle shaft engine and two pulleys and a v-belt. There's more than enough power left over to overcome the power loss of a v-belt. The parts are less expensive and easier to get.


Yea. I think I'm going this route. Simple to build and less moveing parts to break down.

Thanks for everyone's input, Brad


----------



## slabmaster

dirtclod said:


> Ok, ok!. I see the little error that kept it from perfectly balancing. The torque on the Briggs from the chart s.b. 26.26 not 25.25. So the final results should be:
> 
> Briggs w/gearbox = 18 hp and 10.504 ft.lbs. @ 9000 rpm
> 
> That's ~ 3 times the hp and torque of the Husky. I'd say she'll do a good job.


 I see alot of errors! I was talking the same hp. of both and then compared. Ans as for the small husky you compared it to, that's not a milling saw.Try a 395 compared to a 7 hp briggs.At 12,000 rpm not 9,000. See who wins then!:yes:


----------



## Daren

slabmaster said:


> 7 hp briggs.


No one would put a 7 HP 4 stroke on a slabber, we all know it would be underpowered. We are not trying to compare apples to apples here, yes it is going to take more displacement on a 4 stroke, but design (in our imagination ) a doable solution...that gets away from 2 stroke. I have a Jonsered 2095 Turbo that is making 7+ HP (6.7 stock), they were part of Jonsereds chainsaw mill package...I have ripped with it. Boy does that stink compared to running a bandmill.

The original poster said _"All I've really been doing is slabbing, and getting tired of the chainsaw." _We just went from there.


----------



## TexasTimbers

I've got an old Norelco electric razor I never use anymore. I wonder if I took the motor out of that and attached a 9" pulley somehow . . . . . . . .


----------



## Daren

I don't know. dirtclod would be the guy to talk to, he could figure out the math part. You would have the RPMs for sure. Whatcha got goin' ? A big popsicle stick resaw job :laughing:


----------



## TexasTimbers

Daren said:


> Whatcha got goin' ? A big popsicle stick resaw job :laughing:


:laughing:


But nah. Some guy inherited a wooden match stick factory but his religious doctrine won't let him have anythng to do with fire, so he wants a quote on resawing all the macth sticks into flat tooth picks. 

I figure if I can make a small enough micro-slabber I can get 3, maybe 4 picks out of each stick. I am also looking for a market for real fine match stick dust if you have any idees. :nerd:


----------



## dirtclod

I having trouble finding two of the three (rpm x torque / 5252 = horsepower) of the ratings on small engines. Husky published enough info to extrapolate the missing info. But the 4-stroke manufacturers are publishing just their torque without the rpm or horsepower ratings. Consumer Reports had this to say about it and the lawsuits that are being filed over some dubious practices in this area: http://www.consumerreports.org/cro/...00&CMP=KNC-CROYPIHOMEGARD&HBX_OU=51&HBX_PK=pi

I'll keep looking - maybe I can find enough ratings to compare like sized 2- and 4-stroke.


----------



## dirtclod

Ok, I found it on a Honda GXV340 8.9 hp verticle-shaft engine. http://www.honda-engines.com/engines/gxv340.htm 

I'll compare that to a Husky 3120 XP 8.4 hp chainsaw. http://www.usa.husqvarna.com/node3099.aspx?nid=55779&pid=35285

I realize that some of these 2-stroke engines can attain 11,000+ rpm. But I'm going to use 9000 rpm instead. Even though they can rev higher than 9000 rpm, they deliver their peak power at a lower rpm. In this case per their specs their peak horsepower is at 9000 rpm. Besides running a 2-stroke at its max rpm will lead to premature failure. So ideal operating speed s.b. 9000 rpm.

The Honda GXV340 engine has 8.9 hp at 3600 rpm. So using 8.9 hp x 5252 / 3600 gives you 12.984111111111111111111111111111 ft.lbs. torque. For ease, let's round that to 13.

The Husky 3120 XP chainsaw has 8.4 hp at 9000 rpm. So using 8.4 x 5252 / 9000 gives you 4.9018666666666666666666666666667. ft.lbs. torque. For ease, let's round that to 4.9.

The speed ratio of the Husky to the Honda is 2.5. So we need to divide the Honda's torque by 2.5 in order to attain the 9000 rpm of the Husky. So 13 / 2.5 = 5.2 ft.lbs. torque for the Honda at 9000 rpm. So the final tally:

The Husky 3120 XP chainsaw has 8.4 hp and 4.9 ft.lbs. torque at 9000 rpm.

The Honda GXV340 engine has 8.9 hp and *5.2 ft.lbs. torque at 9000 rpm

*You still need to factor in frictional losses in any gearbox/chains or belts and their shaft bearings that are used to step up the rpms to 9000. But it appears the Honda held its own.

The Husky weighs 22.9 lbs. I assume that's dry. The Honda weighs 71.2 lbs. There's one reason why you don't use a 4-stroke chainsaw. The other is that ability to operate in any position. But I think Daren mentioned this earlier.


----------



## TexasTimbers

That's good stuff dirtclod.

But since the 4 stroker will not be turning at 9000 rpm I'll go for all those gobs of torque because the chain speed on the 4 stroker, although slower, is going to stay steady even when you lean in into it like a bull. The rpms on 2 stroker are not going to remain anywhere near 9000 and I bethcya if they go head to head the 4 stroker will kick butt and take names. 

I don't know that for a fact just my gut feeling. When I really lean into my 395XP with the 6' bar on it, the chainspeed drops dramatically. Those last red oak crotches I cut were from standing dead trees that had also been lying around my logyard between 2.5 and 3 years. I had taken them over about a 6 month period so I don't which ones were which, but they were hard as rocks. 

I think I would have had a much better rate of feed with a 4-stroker and a winch to pull the bar through the log. But when you are freehanding a 395xp with a 6' bar from the vertical, you don't need no steeking winch.


----------



## dirtclod

I hope I didn't overlook something and use the wrong formula in converting the rpm and torque through the gearbox. I just did it for the exercise. A qualified engineer would be better. 

Now that I've had time to think about it, what I said earlier about going with a heavier clutch is incomplete. The clutch should be sized to the horsepower but calibrated to the load. Heavier is better...but it would still have to be calibrated so it would slip when it needed to or else it would snap chains.

I don't know if you could stand to watch a chain driven directly at 3600 rpm. You may not be able to push it hard enough to slow it down but it might put you to sleep. Go with a 13 hp engine with a gearbox or belt/chain and pulleys/cogs. This way you get enough extra torque to push it hard and still have full rpms.


----------



## Daren

dirtclod said:


> The Husky 3120 XP chainsaw has 8.4 hp and 4.9 ft.lbs. torque at 9000 rpm.
> 
> The Honda GXV340 engine has 8.9 hp and *5.2 ft.lbs. torque at 9000 rpm


To take this another direction kinda. What does that Big Husky powerhead cost $1500+ ( MSRP was $1729.95 on your link) you can buy 3-4 Briggs of _equal_ power for that money. It is IMO going to take a bigger 4 stroke, I mean why not if you are building might as well get the most bang. A guy can pick up a Briggs 21 HP V-twin for the same money, or an 18 and have some change left for other parts.

I know the "smaller", but still bad boy, chainsaw engines like the 395 that was mentioned are $1000. Or even about the smallest saw _I_ would want to do much ripping with like a 575 is $700 (?)...$700 is going to buy a Briggs/Kohler/Honda pick your flavor, 13 HP.

So apples to apples 2 strokes are more expensive to buy for this application, operate (we know how long a tank of fuel last in a chainsaw, then add the mix oil to that cost) and I have said it before, they just will not last as long.

I know plenty of guys running chainsaw mills, some just love them (they never ran a bandmill :shifty Some get burned out on them pretty quick. This is not a chainsaw mill VS any other kinda mill debate. Just tossing around slabber mill options.

The prices I quoted are new. A guy could buy used and rebuild, but the new price was a best baseline for me.


----------



## AZ Termite

Just to add my two cents. If you are going to go four stroke, you will want to get the honda. I work for a nation wide equipment rental company. I have been there 8 1/2 years, we have had lots of small equip. with both Briggs and Honda, and it has been my experience that the Honda will far outlast the Briggs. Honda engines no matter the size 5,8,11,18 hp are almost bullet proof. They start in 1 or 2 pulls everytime. If they don't, after the second pull you now there is a problem. The spark plug, dirty air filter or water in the fuel are usually the cause, an easy fix. The Briggs after you pull on until your arm is ready to fall off will vibrate itself to death, and they are much noisier than the Honda. If the Briggs won't start it could be a hunt to find the problem.Just my two sents.


----------



## Daren

I will agree. I never pushed it, even though I have mentioned Honda more than once. That is what is on my mill, love it, again like I have said purrs like a kitten (or as your implied well balanced, smooth/quiet running). The business next door to me is a lawnmower/small engine repair shop...he has made small fortune in his life working on Briggs/Tecumseh...never works on Hondas he said and very rarely Kohlers, they just don't need "fixin'"


----------



## Kirk Allen

Not sure of the HP ratings on some of the motors I saw at our Rural King farm supply yesterday but they had a diesel that looked very similar in size to the 18 hp Honda sitting next to it and it was $900. Diesel are known for torque.


----------



## don716

OK, I know this might sound crazy but I have thought of this a while back and wondered if it would even work so here goes. I have a Kubota 21HP Diesel Tractor with a rear PTO rating of 18 hp. Is there a way to rig up a saw mill so that you can pull the tractor up to the mill and connect a driveshaft and start milling?????? Would the rear PTO have enough torque to do the job?I was just thinking how neat it would be to have another use for my tractor. I can run it @ 2600 RPM's all day. Give me your ideas or thoughts on this.

Donny


----------



## bradleywellsoff

don716 said:


> OK, I know this might sound crazy but I have thought of this a while back and wondered if it would even work so here goes. I have a Kubota 21HP Diesel Tractor with a rear PTO rating of 18 hp. Is there a way to rig up a saw mill so that you can pull the tractor up to the mill and connect a driveshaft and start milling?????? Would the rear PTO have enough torque to do the job?I was just thinking how neat it would be to have another use for my tractor. I can run it @ 2600 RPM's all day. Give me your ideas or thoughts on this.
> 
> Donny


Dont see why not. You would have to build a slideing platform so you would be feeding the log thru the mill. One more use for the Kuba.


----------

