Dual headed Chainsaw Mill
- Thread starter PhilB
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Some nice fab work there - did you do it all yourself?
One thing I'm a bit worried about in the long term is the way the mill is locked to the ladder. This means the sideways forces of the chain on the log and the reaction force of the mill on the ladder are not coplanar which will result in a very slight racking of the mill frame continually pushing the bar and chain upwards into the kerf. The reaction to this force will push the chain down against the bottom bar rail. Unless the mill itself is really rigid to prevent this from happening, this may eventually wear the chain and bar unevenly. While your mill does look very rigid the occasional shakes of the mill in the vid suggest that it is still not stiff enough. The situation is magnified because of using a ladder which is quite thick which makes the distance between the bar and the bottom of the mill greater than would be the case if narrower log rails were used. The other factor is is that two power heads means that the forces involved are much greater than for one so the mill frame needs to be even stiffer than usual.
One other thing locking the mill to the ladder does is require the ladder to always be very firmly fixed to the log. This is less of a problem once the first cut has been made but can be a problem on the first cut on some logs especially if one wished to split a log in half on the first cut.
The ideal orientation for the counteracting forces of the chain on the log is for the saw to push back on the log as near as possible to the line of the kerf. This is why people experiment with wheels and sliders etc. I have tried both methods and prefer the ability to move the mill around on the log rails. It enables me to do things like start and finish cuts slowly on an angle. Some of this is because I prefer to work alone - something that is unlikely to be possible with a double header
One thing I'm a bit worried about in the long term is the way the mill is locked to the ladder. This means the sideways forces of the chain on the log and the reaction force of the mill on the ladder are not coplanar which will result in a very slight racking of the mill frame continually pushing the bar and chain upwards into the kerf. The reaction to this force will push the chain down against the bottom bar rail. Unless the mill itself is really rigid to prevent this from happening, this may eventually wear the chain and bar unevenly. While your mill does look very rigid the occasional shakes of the mill in the vid suggest that it is still not stiff enough. The situation is magnified because of using a ladder which is quite thick which makes the distance between the bar and the bottom of the mill greater than would be the case if narrower log rails were used. The other factor is is that two power heads means that the forces involved are much greater than for one so the mill frame needs to be even stiffer than usual.
One other thing locking the mill to the ladder does is require the ladder to always be very firmly fixed to the log. This is less of a problem once the first cut has been made but can be a problem on the first cut on some logs especially if one wished to split a log in half on the first cut.
The ideal orientation for the counteracting forces of the chain on the log is for the saw to push back on the log as near as possible to the line of the kerf. This is why people experiment with wheels and sliders etc. I have tried both methods and prefer the ability to move the mill around on the log rails. It enables me to do things like start and finish cuts slowly on an angle. Some of this is because I prefer to work alone - something that is unlikely to be possible with a double header
Bob,
Thanks, Yes I fabbed the Mill myself.
I've already started redoing the mounts for the powerheads, similar to aggiewoodbutchr's method. This should reduce the shake.
For the first cut I screw wood stops to the cant for sideways movement and shims to support the middle of the ladder. There may be a problem with deep cuts, but the mill is very stiff. The uprights are 1/4" wall thickness. The frame rails are 80/20 1515 extrusions.
Time will tell.
Thanks for your comments.
Phil
Thanks, Yes I fabbed the Mill myself.
I've already started redoing the mounts for the powerheads, similar to aggiewoodbutchr's method. This should reduce the shake.
For the first cut I screw wood stops to the cant for sideways movement and shims to support the middle of the ladder. There may be a problem with deep cuts, but the mill is very stiff. The uprights are 1/4" wall thickness. The frame rails are 80/20 1515 extrusions.
Time will tell.
Thanks for your comments.
Phil
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glennschumann
ArboristSite Operative
Again, nice work!
Very nice work!!! I'm particularly facinated my what appear to be UHMWPE guides on your rig just below the main rails. I've been vexed by the difficulty of having the mill rub against the log, causing muscle sapping friction. The guide plates on a Granberg Alaskan help, but when you are nearing the bottom of the log, the upright of the mill often contacts the log, as the guide plates are so far below the top of the cant, and the top of the cant sticks out so far. I tried putting wheels from a roller blade on my mill, and this helped a bit, but I think I'm going to steal from you, and add an adjustable wheel or two just below the main rails, designed to roll on the side of my 2x12 guide that I always have on my log. I'll post pictures when I complete this... I'm in the middle of milling a 33' 18" ash for a friend (when it is below 90 degrees) and I think this will help... if not, I"ll know why soon.
Congrats on the work!
Schumann
Very nice work!!! I'm particularly facinated my what appear to be UHMWPE guides on your rig just below the main rails. I've been vexed by the difficulty of having the mill rub against the log, causing muscle sapping friction. The guide plates on a Granberg Alaskan help, but when you are nearing the bottom of the log, the upright of the mill often contacts the log, as the guide plates are so far below the top of the cant, and the top of the cant sticks out so far. I tried putting wheels from a roller blade on my mill, and this helped a bit, but I think I'm going to steal from you, and add an adjustable wheel or two just below the main rails, designed to roll on the side of my 2x12 guide that I always have on my log. I'll post pictures when I complete this... I'm in the middle of milling a 33' 18" ash for a friend (when it is below 90 degrees) and I think this will help... if not, I"ll know why soon.
Congrats on the work!
Schumann
This will almost certainly lead to the problems I described above. Despite it's problems the back pressure needs to be on the log not the rails, or the bar should be free floating like a bandsaw mill. Phil's mill looks much more rigid than a consumer mill.
BTW one way to reduce the shakes is to add a bungee cord like this.
It doesn't eliminate the shakes but it dampens them a bit and stops them building up.
glennschumann
ArboristSite Operative
Thanks for the information on attaching the UHMWPE slides. Clever.
I'll keep my eyes (and arms) out for vibrations as I try my modification. I figure that my approach is going to be easy enough to try, and easy enough to verify as I can implement the experiment from the control condition in about 10 seconds in the middle of a cut. I can also "unimplement" it in the same amount of time.
I'll keep my eyes (and arms) out for vibrations as I try my modification. I figure that my approach is going to be easy enough to try, and easy enough to verify as I can implement the experiment from the control condition in about 10 seconds in the middle of a cut. I can also "unimplement" it in the same amount of time.
Existing power head mount
I thought I would post pictures of my existing mount before I posted the new improved mount (stronger I hope). The new mount should reduce the shaking as seen in the video. I hope to be done with it tomorrow.
I thought I would post pictures of my existing mount before I posted the new improved mount (stronger I hope). The new mount should reduce the shaking as seen in the video. I hope to be done with it tomorrow.
Nice fab work!
I should have the mod done in an hour or two. It's looking good.Improved Mount
Here's the improved mount for the power head. The stiffener and clamp are made of 4140 chrome/moly steel. The stiffener (larger piece) is 1/4" thick. The improved mount is much stiffer.
Phil
Here's the improved mount for the power head. The stiffener and clamp are made of 4140 chrome/moly steel. The stiffener (larger piece) is 1/4" thick. The improved mount is much stiffer.
Phil
Yeah I would definitely polish the cover ! 
How easy is it to adjust the chain tension?
How easy is it to adjust the chain tension?
Now that's what I call a chain adjuster! 
Jerry,
Thanks, The bar is a 50" double ended, which with my setup allows for a 35" cut. I do have a 66" double ended bar for a future mill. For now I will use the 50" bar until I get a good handle on any modifications I will need to do. So far it's working out great.
Phil
Thanks, The bar is a 50" double ended, which with my setup allows for a 35" cut. I do have a 66" double ended bar for a future mill. For now I will use the 50" bar until I get a good handle on any modifications I will need to do. So far it's working out great.
Phil
flashhole
Addicted to ArboristSite
Great thread guys, thanks for all the detailed pics and explanation. Nicely done!
