Is there already an established best height for the chain from the surface of the workpiece?
you want the chain to be parallel to the workpiece
you want the chain at a height that roughly balances the sled. The router moves
in and out, so there is no one perfect height.
If the chain is too close or too far away, the sled will tend to tilt away from
the workpiece (top or bottom depending on which direction it’s wrong)
I’m frame designing and looking to design-in adjustable motor mountings so
that chain height may be adjusted based on thickness of sheet material being
this is a good idea. The system can tolerate some chain misalignment and some
inbalance in the sled, but it’s good to be able to minimize this.
Please read the thread ‘musings on frame design’. you really want to make sure
that the motors do not move relative to each other. A design that has a straight
piece of material between the motors is far better than something that gives the
motors leverage to bend things.
Thank you for the advice. I am trying to design in flexibility wherever possible. I intend to make a large rectangular frame with bracing, I figure if I can get a big square frame to start it’ll reduce flexing, and give me the potential to build other things into and onto it. Not quite sure how it’s all going to fit in the garage just yet. Maybe make it inflatable! ;¬)
The unistrut frames I’ve seen so far are awesome! It’s a great way to get a good, rigid frame.
On the note of material thickness, @dlang, you may remember an off-topic tangent I had recently about using a lead screw to adjust the motor position to keep the chain parallel. We could specify the material thickness in the program, so that the motors could be adjusted to always be at the right level for the material being cut.
I’m open to better, cooler ideas to address this, but I just wanted to throw it out there when it actually was in context.
What I would do is attach a block to the top beam so that the gap between that
block and the frame is zero when nothing is mounted on the machine and the sled
is against the back of the machine.
That way you can just loosen up the bolts holding the beam in place, slide it
forward, stick a couple pieces of scrap (one the thickness of your wasteboard,
one the thickness of your workpiece) behind this block, slide the beam back
until it clamps the scrap and you have it set to the ‘perfect’ distance.
realistically though, you should be able to get ± 1/4 to 1/2" (or more) without
any problems, so unless you are going from milling on metal to milling on inch+
thick stuff, you probably can just set it for something that’s parallel with
1/2" plywood (plus your wasteboard) and leave it as-is.
I like it. Much simpler. No programming that needs to be done. I had a feeling that my idea was over-engineered.
In running my machine, I’ve noticed exactly this. I haven’t done any fiddling with the motor position for different materials and I haven’t experienced any chain jumping because of it. I’ve been able to cut at the level of my spoilboard all the way up the the face of a 3/4" sheet of plywood.
I’m in the process of setting up my Maslow and am struggling with how tall to make the frame. I like the alternative design of the stud wall idea, but did not want to make the structure so tall. Is the critical part of the motor placement the height above the workpiece top edge or is it the initial angle of the chain?
I cannot emphasize that point enough. I have a “shortened” frame that’s 112" instead of the full 120" and there is a definite point maybe 6" in from the side of the bed where the chains get too close to vertical and anything cut there is basically useless. In my next iteration of the machine, I’m planning on going somewhere between 120" and 168" to alleviate that problem