Looking for some slabber info.

[Dave Shepard]

I'm curious about slabbing bars and chains as used on Lucas and Peterson slabbers. Are they proprietary? Chain speed and size of chain? Thanks. 

[terrifictimbersllc]

I had a Peterson 10" WPF for 8 yrs. Had the slabber attachment and that is what I mostly used.  The bar was a GB brand and I replaced it twice in 260 hr . Double ended bar, cutting width on the mill was 60"

The chains I made up myself using OR16 harvester chain. 404/063 cut off the tops of every 5 links with an angle grinder, leaving about 12" between pairs of teeth sharpened at 15 degrees. Same as the hyperskip chain that Peterson sold but less expensive.

Peterson upgraded the nose roller during my time to one that had very little wear.

The drive sprocket was a standard harvester one.

I ran a smaller replacement pulley on the right angle gearbox input when using the slabber to increase the slabber speed, to get approx the same chain speed as the 8" swing mill.

I can come up with more details if anyone wants.

[Dave Shepard]

Thanks for the reply. I see Cannon makes an 84" bar. Around $1,200 shipped. Haven't found a GB, but I've only just started looking. Number of pins on the sprocket, and rpms would be good to know. Trickier info would be what hydraulic motor to use. A Peterson DWS would do what I want, but it looks like that's at least a $25k machine. I'm just trying to figure how much I have here, and how much I have to buy.

[Ianab]

The GB bars are Australian made, which explains why you would find them on NZ or Aussie mills. Cannon is probably easier to source in the US, and I see they will do custom bars, so you should be able to special order practically anything. 

As for chain speed, a regular saw is driving the chain at around 5,000 feet per minute. So you need to do a bit of maths using the engine rpm / pulley and sprocket sizes  / chain pitch etc. The engine rpm and sprocket size are generally fixed, so you would use pulley sizes to adjust the sprocket rpm and get optimum chains speed.  The clip on slabbers tend to run the chain a bit slower than ideal, hence the plan of using a different drive pulley to speed it up a bit. 

[Dave Shepard]

Thank you. This will be driven with a hydraulic motor.

[Ianab]

Thank you. This will be driven with a hydraulic motor.

So probably high torque but lower RPM? You can correct for that with pulley sizes between the motor and sprocket drive shaft. Again, some maths needed to work out the ratios. Driving sprocket / chain at ~500 rpm is going to be underwhelming. A larger "harvester" size sprocket might want to be spinning at 4,000 rpm to keep up the chain speeds. It can be done, but you need some numbers to work with. 
 

[longtime lurker]

I've cut a few slabs with a Lucas.  I had slabbing attachment for the 10" mill rather than the dedicated slabber so it wasn't as effective as it could have been but it did a good enough job.

If I was building my own - and I thought about it a fair bit a few years ago - not the way I'd go.

Hydraulic motor for sure but do a google search for "Westford rail mill" look at the rail mill not the slabbing mill which is an improved alaskan setup.
That's how I'd do it...bar vertical means that you don't have to compensate for bar sag by crowning it up with shims. Bar vertical means you don't have to worry about sawdust building up under the bar causing issues. Bar vertical means easy slab removal at the end of a cut because gravity is your friend.

Anyway I thought on it some, figured out a basic vertical mill set up that allowed for a bar nose guide to keep it running straight... had a few talks with my hydraulics guy about motors and gearing.... then figured out I could buy a big band headsaw and a carriage for little more than scrap money and do the same job at ten times the speed without having to reinvent the wheel. Yeah sharpening costs and band costs but for an occasional use machine the dollars added up. 

Since then I no longer do slabs so haven't gone any further but just thought I'd share a different perspective for you to consider.

[Dave Shepard]

Thank you. This will be driven with a hydraulic motor.

So probably high torque but lower RPM? You can correct for that with pulley sizes between the motor and sprocket drive shaft. Again, some maths needed to work out the ratios. Driving sprocket / chain at ~500 rpm is going to be underwhelming. A larger "harvester" size sprocket might want to be spinning at 4,000 rpm to keep up the chain speeds. It can be done, but you need some numbers to work with.
 

TTllc mentioned that the Peterson was basically using harvester chains and sprockets. I'm guessing I'll find a motor from that equipment that will work. I am hoping it will be direct drive.

[Dave Shepard]

I'll check out the rail mill, but much of what I why to do would not be suited to a vertical cut. Tramp metal being a major concern, a big band would also be a concern.

[Ianab]

TTllc mentioned that the Peterson was basically using harvester chains and sprockets. I'm guessing I'll find a motor from that equipment that will work. I am hoping it will be direct drive.

They usually use a jack shaft to both get the gearing correct, and isolate the motor from any vibration feeding back from the chain. Hydraulic motors are usually high torque but low rpm, but you can fix that with a couple of pulleys. 

[customsawyer]

I have the Lucas dedicated slabber. I have only put about 50 hours on it, so wouldn't call myself proficient with it. I bought it used about 5 years ago with 80 hours on it. The first thing I did was buy a new bar, since the previous owner was cutting corners with used engine oil for the lube. I think the new bar from Baileys was around $800.00 back then.

[scsmith42]

Dave, ten years ago I built my own dedicated slabber on a spare Peterson WPF frame.  Some of the detail of the build is here.  I used a 30hp gasoline engine and belt drive.

https://forestryforum.com/board/index.php?topic=76301.msg1158070#msg1158070

Bar is a GB 7' overall length.  I can cut straight through a 6' diameter log.  I used a harvester sprocket (they are hard to find in the smaller diameters - usually have to wait a few months after ordering).  Chains are hyper skip from Frawleys.  Also used to order from Left Coast Supplies and Baileys.

I've played around with chain speeds; currently running around 3600 FPM.  What I found at 5000 FPM was that the chains would stretch pretty badly long before the teeth were worn out.  Slowing down the speed helped a lot.  Sourcing replacement bar tips for the GB bars can be a challenge; last time I purchased from an Australian supplier and it took a couple of months.

If I were to redesign it today, I would opt for a mechanical clutch instead of the electric one I used.  

I recently rebuilt part of it and strengthened the mounting system for the pillow blocks to the frame.  

Let me know if you have questions.

Scott

[Dave Shepard]

Thanks Scott. Good info in that thread. Plenty of challenges to overcome, but that's what makes interesting. 

[scsmith42]

Dave, If i were to rebuild it one thing that I'd seek out is a wider chainsaw bar (at least wider in the middle).  It will sag less and have a better transition to the harvester sprocket.

My system is designed to put a pre-load into the bar from each end to help reduce sag.  It works fairly well.

My driveshaft is 1" steel but the harvester sprocket is 25mm metric (slightly under 1").  Similar to this one:  

https://www.zoro.com/oregon-harvester-rim-drive-sprocket-404-pitch-12-tooth-orc12404xl/i/G706003098/

 What I've ended up doing is sourcing heat-treatable steel shaft from McMaster and then turning down one end to fit the .404 pitch harvester sprocket.  I'm milling a metric slot in the one end for harvester sprocket key, and a 1/4" slot in the other end for the pulley key.  After machining I'm having the shaft heat treated.

Because the lip between the 1" bar and the 25mm sprocket is only around .016, I'm using a 1" shaft collar to snug the sprocket up to.  End of the shaft is drilled and tapped for a 3/8" course thread bolt to hold the harvester sprocket snug against t he shaft collar.

[Dave Shepard]

I met a vendor at LogRite today that has a lot of looong chainsaw bars, and also sells and sharpens Wood-Mizer bands. I'm waffling between band and chainsaw bar for the slabber. They have 8', 10', and 12' bars in stock.

[scsmith42]

Something that Richard (CuttingEdge on FF) once told me what that he though in wider cuts a chain slabber was better because it was more ridgid when cutting through knots, versus a band that would deflect more.

It's a toss up...

[Hilltop366]

When figuring don't forget that a harvester chain takes almost twice the bite as saw chain so running it slower than a chainsaw is not as big a deal as one would think.

I had built a CSM with a 16 hp vertical shaft engine, the first part that failed was the bar tip (Oregon harvester) so if I was doing it again I would run some chain oil directly to the tip bearing or even better use a separate (much heavier) bearing with another harvester sprocket on it using a double end bar.  A good source for a reasonably priced bearing assembly that is designed for side load might be a car wheel bearing assembly, you would need a short stub machined to accept the sprocket.

Make sure you know your bar dimensions before getting the drive sprocket so you don't get a sprocket wider than the bar.

[Dave Shepard]

My Kubota diesel is 21.5 HP. Hoping that is enough. Bar will probably be an eight footer, although it would never see that much in the cut. Realistically, 4-5 is the most it would see in solid wood.

[Dave Shepard]

Finding a gearbox that will work looks like it's going to be challenge. 

[scsmith42]

My Kubota diesel is 21.5 HP. Hoping that is enough. Bar will probably be an eight footer, although it would never see that much in the cut. Realistically, 4-5 is the most it would see in solid wood.

Dave, if a 5' diameter log / crotch is the widest that you will ever mill, consider a shorter bar.

Wider bars 

1 - have more sag to deal with
2 - require longer (and more expensive) chains)
3 - are heavier and more expensive.

I have a 7' bar, and have a 6' maximum width of cut by the time that the support distance is factored in on each end.

Also (and this is very important), you will want a means to make slight adjustments to the bar angle on each end.  When I first built my slabber, the dimensions were so precise that I did not need to have an angle adjustment.  However, in ten years of use the wear on the components has put play in the bar so that I've had to go back and fabricate an adjustment system to keep the bar from diving in the cut.

Some diving will occur naturally when one edge of the chain wears more than the other (dirt / rocks in bark, etc) so you can never get totally away from it.

As far as gearboxes go, Surpluscenter.com is your friend. Here is one related for your HP for less than $200.

https://www.surpluscenter.com/Power-Transmission/Gear-Reducers-Gearboxes/Gearboxes/1-1-32-HP-RA-Gearbox-Same-Rotation-In-Out-13-1423-S-G.axd

Various ratio's are available.  My engine rpm to shaft rpm is currently pretty much 1:1 but your diesel RPM is probably lower than my 30hp gasoline engine, so you may want something different.

[Dave Shepard]

The primary purpose for this mill is to cut long curved timbers for crucks, and tall forked posts. Not a lot of actual wood, just a lot of width. Those gearboxes have a maximum 1,800 rpm input speed. Also, not sure they can be run with one shaft in the vertical orientation. 

[Hilltop366]

I was thinking a while ago that if I was to make another CSM I would be tempted to do away with all the extra drive pieces like pulleys, belts, jack shaft, bearings and clutches and mount the saw sprocket direct on the engine shaft I think I would also use a deadman kill switch on a push bar kind of like a push lawnmower.

[Dave Shepard]

I'm thinking electric is the real way to go. I just don't have a working genset right now. 

[Hilltop366]

The primary purpose for this mill is to cut long curved timbers for crucks, and tall forked posts

Maybe a wacky idea but that has never stopped me from saying it out loud before.

Could a person take a bandsaw mill head from a 2 or 4 post mill type and put solid rubber wheels on it?

Put the log on a flat deck and push the mill around the curve, for a forked post go up the post as far as you can then finish coming back from the other ends.