2 post vs. 4 post mills

[welderskelter]

I am building a two post mill but I see there are quite a few guys with four posts thought I would find out which is liked the best. Harold

[Dan_Shade]

my opinion is the quality of the blade guide mechanisms and the rigidity of the frame are what comprise the quality of a sawmill.

[Left Coast Chris]

Hi Welder,

The hardness of the round stock that the rollers ride on is very important for the cantilever head mills.   Be sure to not use mild steel.  It will form a flattened surface on the round stock over time and the head gets much more difficult to push. 

[pineywoods]

Most of the folks that bad mouth the cantilever head mills ain't never run one. There's lots of advantages to a cantilever head, especially if you're gonna saw large, knotty, limby logs and stuff like crotches. BUT building one wouldn't be a trivial project. 4 poster would be much easier to build. My hat's off to anybody who builds either kind. Then there's the swing mills, a whole different ball game.

[bandmiller2]

Harold,I think you mean one post on each side of the track ways,not cantilever.Yes you can but four posts would tend to be more stable and give you more latitude in the future for repowering or outher modifications.With two posts balance becomes more critical,of course for a simple manual it will work OK. Frank C.

[ladylake]

 I think a 2 post with good heavy metal should work fine, maybe even better than a 4 post mills which don't seem to have a lot of cross bracing. Make sure to use a long enough cross piece on the bottom so no weight is hanging out past the wheels.  Steve

[welderskelter]

Yes, Bandmiller2 you are right. I didnt mean cantilever. I used 4x4x3/16 Tubing for frame. I think it feels solid enough.  I just didnt care for the 4 post configuration because of the many different stress places. A square box can be a welders nightmare when it comes to twisting. I can make adjustments easily on a 2 poster. Thanks Harold

[ladylake]

  I think you'll end up way more ridgid with your 4" 2 post mill than with a 4 post with 2" tubing.   Steve

[welderskelter]

Yes ladylake, but I can also heat one spot to correct a misalignment rather than 2 or 4 . I believe the guys on here that have heavy mills seem to have less trouble with sawing than the lighter mills. Just my thought. Thanks Harold

[Tom]

Heft is important, but not the most important. A sawmill is better made to have adjustments for fine tuning than depending on a torch to bend metal.   You will probably be regularly putting logs on your mill that will exceed a ton.  As we have, you might even put them on there that are in the three ton range.  I dare say that some mills have seen logs bigger than that.  They aren't always tenderly and gingerly placed, but get dropped and rolled onto flat spots. It's a real war zone.  Not to mention the stability and support of the landing gear that has to prevent twisting and bending.

If the mill is to be transported, weight becomes a factor, for licensing.

I have run both 4 posts and Woodmizer's cantilever mill.  Much of the negative hype about cantilever mills is just untrue. If you look at the cantilever from a bit of a different angle, you realize that it is a four post mill too.  It has two rails, one above the other and there are posts that support the head of the mill that ride on each rail.  It's just that we speak of 4 post mills as having 4 equal sized legs that are horizontally aligned rather than vertically aligned, that we make much of a deal about it at all.

A two post mill with one stanchion on one side and one stanchion on the other side, is still a 4 post mill, in my mind. For stability, the points of contact with the rails define the style, not the manner in which the points are reached.  With one stanchion on each side, there will have to be a lot attention spent on the twisting. The distance from the wheels to the stanchion will produce a pretty good bit of torque on connections.

'Course, I have to go back to an old analogy from my motorcycle racing days.  Every track has a groove that is supposed to be the fastest way around.  If everybody stays in that groove, following that idea as gospel, the race will conclude in a single file of racers.  Somebody has to get out of the groove and do something different if they stand a chance of winning.

So, experiment away!  Perhaps you'll do something that no one has ever thought of. 

[welderskelter]

Thanks for all the input has been great to hear all the different opinions. I have more questions than you can shake a stick at but I better start a new post for that. Thanks and yall come back now ya hear.

[welderskelter]

How much adjustment do I need to build into my band mill to accomodate different length blades? Not all blades are exactly the length you order are they? I am going to be using about 24 in. tires with approximately 50 in. between centers . Need to know how much slide I need to put in for different length blades. Thanks Harold

[Meadows Miller]

Gday

sorry i missed you there back in november  welcome to the forum Mate  ;) ;D ;D ;D 8) 8)

With blade adjustment 4" of travel will be more than enough  ;) and when you measure the band length do it with about 1" from been closed hard up as this will cover you against getting in a bind if you get a short band aswell mate  ;)

Regards Chris

[Tom]

You might find that you had wished that you had put everything in one thread.  Talking about the same subject (your sawmill) on different posts can have other posters wondering what they are talking about.  Later on, you will want to collect everything into one spot and it will be scattered to the winds.

[bandmiller2]

Hal,are you using the 4x4 for the carriage uprights or for the ways the carriage runs on??The carriage that carries the bandsaw is like an upsidedown "U"you can't crossbrace at the bottom because it would interfere with the log.It helps if you use "V" wheels on boath sides to give some support at the bottom of the carriage.Use ball and roller bearings whenever possible.The more ridgid you build the easier to get good cuts.Frank C.

[shinnlinger]

Lots of good info here.

I will only add that My Turner is a 2 post and it has cut lots of very accurate lumber IF I have a sharp band,  adjusted guides and keep the rails clear of junk from time to time.

Dave

[welderskelter]

Thanks Chris. I was wondering just how close they get to the right length. I thought 4 to 5 in. might do it thanks. Harold

[Fla._Deadheader]

I'm thinking we have 3 inches of travel on the tension bolt. Figure it will give you double the distance, because the blade runs both ways. It's not like a piece of rope.

  2" will allow 4" of blade length. We never had blades very much out of length. All they try to do is, match where the teeth join, so sharpening is not messed up.

[jpad_mi]

I designed for 3inches of travel when I had a threaded tensioning system. I changed over to hydraulic tensioning and went with a 1.5inch stroke cylinder because I got it cheap. I was worried that it wouldn't be enough stroke, but it has been fine. I'd feel better with three inches though.

[Fla._Deadheader]

"V" wheels on both sides, You better have that track 101% dead on. If not, BIND City, or carriage climbing up the track, producing uneven cuts. Have to modify mine a tiny bit, and, my track is just about perfect.

  I'm going to spin my unguided wheels on my lathe, and use a side grinder to widen the grooves a tad.

[beenthere]

FDH
I'd heard of a reason that the tracks are not both for "V" wheels.  And you reminded me what it was. 

[Fla._Deadheader]

Glad to be of assistance, BT.  8) 8) ;D ;D

[bandmiller2]

I have "V" boath sides just takes a little longer to fine tune,also a little endplay on one side helps. Frank C.

[Tom]

you can have v wheels on both sides if you do as Baker has done and let one side float on the axle while the other side ties the head to the rail.

[logwalker]

You should be able talk to blade supplier and find out the actual sizes available. Because of the 2 alternate tooth/1 raker tooth pattern there are set sizes. You need to keep the number of teeth divisible by 3 so your automatic setters can work properly. Good thing you thought of this now.

Joe