I am going to be setting up my frame in a few days and I have been looking at the “bolt together” design. I am thinging of actually building this frame: https://www.summet.com/blog/2018/03/03/long-board-sheet-storage-maslow-cnc-frame/
because of the additional storage or modifying either design to fit into my small workshop.
From all the designs it seems that the requirement is the upper chain motors need to be exactly 10’ across. If I modify a design or build one of my own what are the requirements for the maslow to work right?
Does the angle of the sheet need to be exactly 15 degrees
does the distance from the motors to the base that the 4x8 sheet sits on need to be a certain distance?
10 feet is fine, 12’ is better, but you need longer chains.
distance from top should be 24 to 30" . the default 18" is a little low IMHO.
15-10 degrees is fine. there is a spreadsheet that calculates forces if you really want to dial it in.
why does a wider top cross beam distance work better? more accuracy?
So as long as I have at least 10’ across the top and at least 18" from top of 4x8 sheet to the top cross beam I will be ok? once I set everything else up I can dial in the specifics?
the problem is that as you get to the bottom corners, the chain to the near
motor gets close to vertical. That means that gravity doesn’t provide much side
force to swing the sled into the corner. A wider top beam means the chains are
not as close to vertical in the bottom corners.
as you get to the top center, the chains get closer to horizontal, which means
they have to pull really hard against each other to move the sled up. This
either runs out of motor power or wears the gears out sooner. moving the top
beam higher means the chains are not as close to horizontal in the top center.
making it wider hurts the top center (but not as much as it helps the bottom
corners)
making it taller hurts the bottom corners (but not as much as it helps the top
center)
so going both higher and wider than stock helps both [1]
this spreadsheet lets you play around with dimenstions to see how what you are
looking at compares to stock (including allowing you to define different
workpiece sizes)
as for angle, we know that it doesn’t work at 20 degrees. we know it doesn’t
work at 5 degrees, 15 degrees was the stock design and we haven’t had people
systematically report tests at other angles, we thing it will work better closer
to vertical, the one concern is driving the bit down into the wood.
David Lang
[1] The maslow is very much a ‘just barely good enough’ machine design. there
are lots of things that can make it better, but they add cost and/or size to the
design.