cutting long beam with CSM

[Backwoods]

I got a 27’ log that I am planning on cutting into two beams for the frame of my bell saw circular mill. I have a have a home built csm that is 48” (60” bar) that I have never milled with. The log is Doug fir and straight with no tapper. It measures 16” at both ends.
I see where a cross piece fastened to both ends of the log with rails sitting on that is common. However the longest boards I have are only 20’ long. Are there some tricks to setting up a straight edge for cutting long logs?

 

[peterrum]

Check the posts here on Malloff's book "Chainsaw Lumbermaking". Check out Chapter 8. He uses a system with running a string along the top of the two endboards then putting lag screws in the top of the log to support your top guide board. It might work for you or you can rig up something similar. With his method you can cut beams up to 50' if you want. Good luck

 

[excess650]

I just extend my 10' 2x4s by screwing others to them. As long as they are properly supported to limit flex, vibration, and sag, its not problem.

 

[mtngun]

Even if you had a long enough guide board, it would require several middle supports to span 27 feet.

Malloff's lag screws are one method, but awful time consuming and lotsa luck getting them perfect.

One thing I have done, is chainsaw a notch in the top of the log, midpoint along the log's length, about 1 1/2 feet long, and about 4" deep. Basically, you cut out a chunk of what would normally be the slab. Now you can screw a board on the edge of this notch, to support the guide board. Height of this board is determined by stretching a string over the end boards, similar to Malloff's lag bolt method.

For a 27 foot log, several of these middle supports would be appropriate.

To me, this method is faster and easier than zillions of lag bolts.

 

[Backwoods]

Today I set up the chainsaw mill and cut two sides of the log that I am making beams out of. Setting up the saw takes a considerable amount of time. It took well over an hour to get the bar changed and the mill bolted up to the bar, the dogs had to be removed to mount the mill on the saw.

The saw seems to be upside down to me but the adjuster bolt on the mill will not allow it to mount the other way.

I took the small saw and knocked all the high spots off the log so that the 2x8 would sit solid on the log. I nailed stickers on using small nails to help hold the 2x8 in place.

I made the first cut by myself, and the oldest boy showed up while I was sharpening the saw and helped with the second cut. This works much better and cuts smoother with two people on the saw. Note that in the forth picture there is a stinger on the bar, a guard on it will be in place before I use it with a helper. (I ran that end)

I still have the two squaring cuts to go and then split it in half to make two 6x12 beams.

 

[peterrum]

One thing I have done, is chainsaw a notch in the top of the log, midpoint along the log's length, about 1 1/2 feet long, and about 4" deep. Basically, you cut out a chunk of what would normally be the slab. Now you can screw a board on the edge of this notch, to support the guide board. Height of this board is determined by stretching a string over the end boards, similar to Malloff's lag bolt method.

I like this method also mtngun.

 

[RPM]

Why such a long bar for this log? Your power head looks like it might balance the whole rig but otherwise I have found it hard to balance a setup like that with the excess bar and mill out riggered to the side.

And I can appreciate that might be the only bar you have....so ignore my question if so.

 

[irishcountry]

Looking good you got it done thats all that matters good job

 

[deeker]

Backwoods, it looks great!!!!

 

[BobL]

Good job, don't forget to post the final pics of the beams.

The saw seems to be upside down to me but the adjuster bolt on the mill will not allow it to mount the other way

The way you have it is the normal way. Mounting the other way would mean the throttle would be even lower than now meaning you would have to bend a little more to get your hand onto the throttle.

 

[Brmorgan]

I use Malloff's end block / chalkline / lag-bolt system almost solely, but then again I use a 14' 2X8 as my guide so it's not as rigid as a ladder or Unistrut etc. I carry a Lithium-Ion 18V impact driver to drive the lags though, so I don't find it takes too much time to do. I couldn't imagine driving them all with a brace & bit or ratchet. I also drive lags down through the guide board into the log - this lets me fine-tune for flat as I can suck certain parts of the board tighter to the log if needed.

I've never cut anything in the neighborhood of 27' long, but the 20' beams I made this summer were done with only a 10' guide board and the lag bolt method, and turned out almost perfectly flat. The only inconvenience I find with the method is having to carry around a case full of different bolt sizes and lengths. I do have plans for a better system by next season.

 

[woodshop]

Good job... never tackled anything more than 14ft long, and that was a pain to keep strait and even.

 

[Rockfarmer]

Like BRMorgan said theres nothing straighter than a tight string It is the best guide

 

[Backwoods]

Why such a long bar for this log? Your power head looks like it might balance the whole rig but otherwise I have found it hard to balance a setup like that with the excess bar and mill out riggered to the side.

And I can appreciate that might be the only bar you have....so ignore my question if so.

I have two other bars and a stack of chains just not a shorter mill. A smaller mill would be easier to balance. The bottom cut was much better then the top cut. I as soon as I get my new fuel tank for the bandmill I plan to set this log on and make three cuts, which will give me a pair of 6x12. That will also allow me to compare how much work is involved in both methods. The band mill had a 20’ bed on it but with the aid of the forklift and some blocking it should be capable of milling a longer log like this.

 

[Backwoods]

Same saw shorter bar shorter mill (barrowed) cutting results were about the same just a bit easier to handle.

Note that the beams are about as straight as the road. They will work for what I need them for.

 

[peterrum]

They will work for what I need them for.[/QUOTE]

At the end of the day thats all that matters, good job.