For adjusting the length/width, I've been tossing around a different idea that I THINK might be a bit easier and more versatile, but I'd like your opinion. Use some bar stock, maybe 1-1/2" x 1/2" to tie them together, and machine a groove in them so that one rail can slide along it to set the width. Much like how it appears your end angle iron pieces are attached (hard to tell in that photo). The bar stock would add a bit of weight over the allthread you're using but there would be no holes to line up - just loosen the bolts and slide the rails to length and width, then snug them up again. It would also add some rigidity and might help with the twisting. Even aluminum bar stock might have the necessary strength and would cut down on weight a lot. Alternatively I guess you could use some lengths of the low-pro strut I mentioned earlier and that would save you having to machine a groove too. I don't know if I'm doing a great job of explaining what I mean, but it's kinda hard to take pictures of an idea before it's built.
Basically though the cross braces would attach like those on the Alaskan mill with the added capability of variable width. What do you think?
I think I know what you mean but a diagram would be useful.
Obviously the cross members can't go on top because the mill needs to slide on the rails but underneath also has some complications.
On about my 3rd set of rails I did use cross pieces of 1/4 x 2" solid steel stock. Even this setup still twisted for lengths over 10ft. It looked like this;
To support the rails I made a dozen or so adjustable length spikes that ride in the rail and stick into the log.
The support provided by the spikes was not all that good and (as seen before on this site) I think bolt heads riding direct on the bark would be better. However, the reason I gave up on this is because I mill a lot of weirdly shaped pieces of wood, when there are variables lengths of metal (Spikes dangling down from the rails) one really needs to know where they all are and after two accidents where I ran the chain into the spikes I threw them into the metal scraps bin. There was also an awful lot of mucking about sliding on/off the spikes.
I have since settled on this setup as I think it is the most stable when cutting the first slab.
I try and arrange the inner edges of the rails to sit on the log and the all thread cross pieces to sit on, or in grooves in, the bark. I usually put the rails on the log and adjust the width, and then adjust the end pieces to suit, mark the where the all threads cross the log, remove the rails and cut grooves in the bark with a CS for the all thread to sit in. Of course not all logs will have all three contact points available. In some cases with longish distances between contacts I place wooden wedges under the rails. This has worked well and if the chain runs into the wedges its no big deal.
Here is a view of the adjustable ends - these work very well, especially being able to screw those bolts into the end grain.
I have slabbed some crooked short (6 ft) logs where only these end pieces have been supporting the rails - this worked fine because the rail is heavy duty.
Working in a yard means not having to carry my rails too far but if ,and when, I go bush I will have to make myself a lighter set of rails.
Cheers
The dust flys!
