That’s fantastic news! Thank you for running the test and the update.
I made a couple tweaks to the carriage pieces you are using and designed a laser cut steel ring which I’d like to explore as an option to replace the bent one which you had to dial in. Those were sent off to the factory this morning so we should have samples back in a week or so 
I’m really jazzed that both the pantograph and ring sled designs seem to be working out! I already bought on of @pillageTHENburn’s kits, so we will start with the pantograph, but it’s nice to have options.
However, I’m still wondering about @pillageTHENburn’s source for unstretchable twinkies.
This ring sled design is really coming along nicely! Some of the test pieces look amazing.
Has anyone designed a sled with all the holes we would need, plus maybe, a shallow ring and maybe some screw holes for brackets (the shallow ring cut into the board would be for aligning the brackets and metal ring). It seems like a well designed sled could ensure the bit is centered inside the ring… right?
Can definitely work on that!
I’m happy to add it to the Fusion360 file once it’s complete.
I just wanted to keep this thread alive and let everyone know that while We’ve been mostly focusing on getting the kits shipped, I’m still working on this idea as much as I can. What I am playing around with right now is a cut metal ring which mounts to three of the same bracket used for the z-axis to allow it to be adjusted vertically. This also removes the need for bolting through the sled making it easier to put together.
We would offer a couple different sizes for different routers.
One part that I haven’t found a good solution for yet is how to make it easy to find the center to position the router. Does anyone have thoughts on how to easily find the center of the arc?
Here’s my work in progress. Please ignore the ugly free hand plasma cut around the outside 
Difficult with the router in place, but I’d try screwing a piece of 3/4" to the bottom side and pecking a 1/4" axis hole through it with the z axis, then remove the router and base and put a piece of 1/4" stock in the axis hole, taller than the ring height above the sled. A one-armed ‘calibration piece’ with a 1/4" hole in one end and something (an edge? a sliding stop?) at the radius of the circle would align the fixture. A 3-armed calibration piece would make it easier, though more expensive.
Oooo I really like the idea of making a part that does the measuring for you. I hadn’t thought of that.
Let’s not worry too much about the router being in the way because most of the time we will be assembling the sled from scratch and we can do it in either order.
What if we used the ring itself to be the calibration piece? The ring could be flipped over and traced onto the surface of the wood. There could be some marks on the ring itself (notches in the outer edge, or holes in the ring) and connecting those points with a straight edge could make a cross at the center. After that it is just a matter of mounting the ring on the traced lines and mounting the router at the center. Maybe I’m making this too complicated…
If the line between those two marks passes through the center of the circle and we mark the points on the line where it crosses the inside edge of the ring, then the midpoint of that line segment is the center of the world.
If there were two holes drilled into the body of the ring spaced one radius apart (driller anywhere out of the way), an appropriately sized pin/nail thru one into the center of the sled would make the other hole describe the location of the ring.
If the line between those two marks passes through the center of the circle and we mark the points on the line where it crosses the inside edge of the ring, then the midpoint of that line segment is the center of the world.
-or-
If there were two holes drilled into the body of the ring spaced one radius apart (driller anywhere out of the way), an appropriately sized pin/nail thru one into the center of the sled would make the other hole describe the location of the ring.
Could also cut a disc to fit inside the ring to center it.
I figure that most people building a Maslow will have a router. Adding one pivot hole to the temporary sub-base makes cutting accurate discs really easy. The pivot hole is then used as the center hole for laying out the rest of the base.
Screw the disc into place, set the ring in place and mark the mounting points, then remove the disc and assemble. You can center the router over the hole with a vee-bit or a small diameter bit, then once the router is mounted, cut out the center of the router sub-base for dust collection and chip clearance.
a good ring should have the brackets set so they don’t interfere with the
wheels, so the exact orientation should not matter. Use the principal of
equalteral triangles to mark out the holes.
the fun is in cutting it exactly the right diameter so there is no play. that
can take multiple attempts.
Not sure I follow here. Equilateral triangles with one corner on the center and side = r would locate points on the circle, yes.
I was looking for ways to accurately place the laser cut circle centered around the router using marks or holes machined in the circle bracket.
Sure, but if it is a touch too small, it can be easily shimmed to take out that last bit of slop.
I build loudspeaker cabinets, so I have a specific router jig that can cut circles to a very high degree of accuracy. Before I elected to try the linkage approach, I was considering a ring sled. I was planning to plasma-cut a ring like Bar’s with a simple pivoting jig, then center it on the base plate in this manner.
flip the triangle upside down, with two mounting holes at the upper corner. put
screws through the two holes, then remove one and loosen the other, use it as a
compass to trace an arc, then replace the first screw and remove the second,
trace a second arc. where the two cross is where you want the bit to be. Drill
a 1/4" hole there, put a 1/4" bit in the router, with the router off, plunge the
bit into the hole to hold things in place while you fasten the router to the
base, then you can remove the router and use a hole saw (or router) to enlarge
the center hole.
I wish I remembered my geometry enough to come up with that 
and some people said we would never use that stuff
As the ring will be a fixed size, perhaps a paper template with markings will suffice? Simple to perform
