Would a U-shaped chainsaw mill be plausible?

[StevenBiars]

So I was tinkering with some mill mock-ups last night, and I started scribbling some designs. In the process of doing so, I improvised a possible *cheat* for those of us that lack a longer chainsaw bar. My initial thought was of constructing an Alaskan type chainsaw mill, but employing a double sided track, similar to a paper clip. This would allow the sawyer to cut down one side of a log, rotate, and then finish the other side. Since the bar length would be shorter, in theory it wouldn't suffer from nearly as much sag as a larger counterpart. The first side to be cut would have kerf-sized spacers placed to compensate for sagging so that the other side can be cut. Thoughts on this?

 

[BobL]

So I was tinkering with some mill mock-ups last night, and I started scribbling some designs. In the process of doing so, I improvised a possible *cheat* for those of us that lack a longer chainsaw bar. My initial thought was of constructing an Alaskan type chainsaw mill, but employing a double sided track, similar to a paper clip. This would allow the sawyer to cut down one side of a log, rotate, and then finish the other side.

So you want to run a single sided mill with the bar buried up to the nose down one side mill and then run it along the other side?
If so, that's an interesting proposition.

The biggest issue I see with that is the load on any saw with a bar that is trying to rip with the bar buried up to nose. Any saw doing that constantly in a rip cut, runs a hotter powerhead and hotter bar and chain because there is no chance to aux oil the B&C.

Since the bar length would be shorter, in theory it wouldn't suffer from nearly as much sag as a larger counterpart. The first side to be cut would have kerf-sized spacers placed to compensate for sagging so that the other side can be cut. Thoughts on this?

Single ended mills might not suffer from sag but they do suffer from droop. If they have the same droop for each cut on the same side of the log it doesn't matter because the cuts will all be parallel to each other. But if the log or saw are rotated, then the opposite cut will be out by twice the original droop. I"m not saying it's impossible but some serious form of kerf alignment and bar droop adjustment mechanism will be needed. By the time that gets sorted it is probably cheaper and a lot easier to get a bigger bar.

Probably more than most I like to complicate my mills but given what I know about single and double sided CS mills this is one approach I would not give a second thought to even on a drawing board.

 

[Timberframed]

I think it might work. Some of those Granberg mill frames don't support the bar at the nose but it would be a plunge type cut for the first haif of the log. Chip removal would be an issue then.

 

[mtngun]

Will Malloff made some mills that operated on that principle, but they were not Alaskan type mills.

Seems like the Granberg Small Log mill could be used as you described, but I don't know why anyone would want to do it that way. You'll be making 2 passes instead of one, so the already slow process would be even slower.

 

[Talltom]

The Logosol mills use a guide on one side of the log. This works well when cutting completely through the log, but not as well when the nose is buried. I have used the Big Mill system with the saw captured by the guide rail and the Timberjig with a wooden rail to quarter logs that are too big to put up on the mill. I always get some twist to the cut when the nose is buried. This is true when using the same bar and chain that cuts straight when the cut goes all the way through the log. The twist seems to always be downward at the tip as the cut progresses. Could be that the rotation at the tip pushes it down, or that the additional sawdust buildup does the same thing, or that minor existing problems with the bar and chain or set-up are magnified by the additional stress. I have not tried cutting from two directions with the log up on the mill, since logs that size are usually too heavy for mill. Once the log is cut in half, I can quarter it without burying the nose. I mark the original cut faces, shim them on the mill to average the twist, cut them from the bottom a little thick and plane the marked face. Lots more work on four boards, but the rest come off the saw flat and straight.

Your idea might be a good cheat for a few cuts where you don't have a long enough bar, but I wouldn't expect accurate cuts and it would be of little advantage when slabbing the log. BTW, if you do cut from two directions, you will gt better results if the tip is only a little past the center of the log.

 

[hamish]

I always get some twist to the cut when the nose is buried. This is true when using the same bar and chain that cuts straight when the cut goes all the way through the log. The twist seems to always be downward at the tip as the cut progresses. Could be that the rotation at the tip pushes it down, or that the additional sawdust buildup does the same thing, or that minor existing problems with the bar and chain or set-up are magnified by the additional stress. I have not tried cutting from two directions with the log up on the mill, since logs that size are usually too heavy for mill. Once the log is cut in half, I can quarter it without burying the nose. I mark the original cut faces, shim them on the mill to average the twist, cut them from the bottom a little thick and plane the marked face. Lots more work on four boards, but the rest come off the saw flat and straight.

When the nose is burried, and tension in the wood has a real hard time trying to sort itself out as it is still partially attached to the wood beneath it. Thru and thru cuts do still react but no where near as a kinda cut, cut (cant think of a better word right now).

 

[dfdye]

I have done a few logs with the "around the world and back again" method described, and I would only recommend it if no other option exists. From a cut quality standpoint, the tip being buried creates a pretty gnarly pattern in the center of the board which was magnified by the fact that my kerfs didn't perfectly line up at the end of the "return" cut. I am sure that some of this could have been mitigated by making fine adjustments to the mill, but I don't see this method as being practical for much more than the one-off cut that your normal mill can't quite handle. There might not be as much "sag"'with a short bar, but the tip will still act up in the cut (well, at least that's what happened to me!)

BTW, my experience was with an ~30" white oak from a neighbor's yard, and I used a 20" bar with an open ended mill for trying to get some full width slabs. After doing a few of those, I just quartered the other logs and used my 28" bar for normal milling. I'm nowhere close to an expert on milling, so this may well be a viable method for a more experienced operator, but I certainly won't be doing it again unless I'm stuck and don't have another option.

 

[820wards]

I think it might work. Some of those Granberg mill frames don't support the bar at the nose but it would be a plunge type cut for the first haif of the log. Chip removal would be an issue then.

Milling half a log would defiantly generate more heat on the bar trying to cleat sawdust chips. I milled a log with my mini-mill where the bare was not long enough to cut clear through the log. It really worked the saw harder than I liked and the bar/motor were much hotter when I finished.

Bob mentioned that there would be no way of oiling the nose of a bar buried so deep and then there is a problem with the log pinching the bar. On the log I milled I had to use wedges every 6" or so just to keep the log from pinching the log, and this log was maybe 18" across. Now try that with a 30 or 40" log I'm predicting an engine meltdown.

jerry-

 

[StevenBiars]

Milling half a log would defiantly generate more heat on the bar trying to cleat sawdust chips. I milled a log with my mini-mill where the bare was not long enough to cut clear through the log. It really worked the saw harder than I liked and the bar/motor were much hotter when I finished.

Bob mentioned that there would be no way of oiling the nose of a bar buried so deep and then there is a problem with the log pinching the bar. On the log I milled I had to use wedges every 6" or so just to keep the log from pinching the log, and this log was maybe 18" across. Now try that with a 30 or 40" log I'm predicting an engine meltdown.

jerry-

I suspected heat and oiling may be an issue, but I thought I would ask. The problem arose when I started considering a chainsaw mill as a side project to the bandsaw mill I'm currently working on. I certainly wouldn't want to try it on a huge slab, but I was curious to see what might happen if a bar were a few inches short of cutting through the log. The reason for this is that I've come across quite a few logs that are flared or bent in places and my bar certainly won't make it all the way through in some of the flared areas.

-Steven

 

[820wards]

I certainly wouldn't want to try it on a huge slab, but I was curious to see what might happen if a bar were a few inches short of cutting through the log. The reason for this is that I've come across quite a few logs that are flared or bent in places and my bar certainly won't make it all the way through in some of the flared areas.

Steve,

OK, now I know what you are dealing with. I to have had logs that I have milled with my mini-mill that did not protrude the full length of the chainsaw bar, maybe 1-2". Encountering that, I used wedges along the cut to keep the log pinching the bar. I ended up free had cutting those pieces apart. If you will be mill the entire length of a log that, say, has 3-4" left to mill, it will pinch the bar and you will need to use wedges to keep the saw cut open. You'll know when it's starting to pinch the bar. I found that if I had a helper with a hand full of wedges, he could tap them in with my wood mallet as I milled along the log.

Speaking on the flared part of the log. I usually try to free hand cap that part of the log off anyway to make it easier to set my rails level to the pith unless you plan to use that piece for something like a stool back.

Good luck and have fun milling.

jerry-