Gentleman,
I would like to share with you my latest experience with my new build: Maslow Mark II - 3D.
My main objective was to improve accuracy, makes material handling easier and add 3D capabilities.
I addressed most of the “best practices” as described over several forum threads.
- Rigid and level frame.
- Motors and ring on the same level as centre of gravity so chains are parallel to work surface.
- Concentric router bit and ring axis; removing ring flexibility.
- Simplification of Z-axis
For now it looks like this:
As much as we all like to work with wood I decided to follow excellent design of @rbodelon [Maslow without Stretchy String, bungies or elastic cord only blind rollers]
His design is simple, rigid and most important enables level adjustment - thank you @rbodelon.
Using 40mmx40mmx2mm steel profiles, self tapping screws and torque driver, one can easily assemble frame and add simple adjustment to control beams level and beams aligment.
Sorry Maslow but I replaced famous bricks with cans filled with 2x2.5kg of melted lead. It is much more compact design and allow to lower centre of gravity. The centre of gravity, ring hight and motor sprockets are at the same level above work space - chain is now parallel to work surface.
The chain slack is tensioned by rope, two pulleys and 2kg of weight. Chain slack is kept parallel to work surface - it solves many problems with friction on motor sprockets.
Next challenge - concentric ring. As described in Ring and bit alignment - printed kit, simple pattern can be printed (or cut using Maslow) aligning router axis with the ring axis.
Simple modification of AEG/Rigid router makes very functional Z-axis as described in Z-Axis mod with AEG/Ridgid router
3D challenge.
My new router (AEG/Rigid) accepts 8mm bits. Usually such bits are available in 35mm lenght (at least ones which I can afford). Bits length is limiting factor in workable Z depth and 35mm is plenty for my boat projects (or sculpting doors and table tops projects).
If sled is replaced by gantry, there is potential to replace router with cutting laser, or plasma torch, or circular saw and convert Maslow to a multi tool cnc machine.
This is my take on that challenge: the principles of moving router stays the same but I replaced sled by gantry and carriage. I design and printed brackets to assemble X gantry and Y carriage using the same steel profiles as for frame. Cheap ballbearing on M8x40mm screws are perfect for rolling on the steel beams.
Printed brackets accurately positions ballbearings and makes gantry’s beams square within 0.1mm. No needs for precise drill press.
The gap between gantry and work top is 40mm allowing easy slide in and out sheet of plywood - sled is not interfering with material.
I assembled my Maslow, calibrated it with 1.12 firmware and GC, and cut test using 8mm bit. Here is benchmark test result:
- using old spreadsheet (average error): -0.1mm for long and 0.1mm for short
- using new spreadsheet (average of abs (error)): 0.5mm for long and 0.2mm for short.
I am pleased ;-)) I think that rigid and level top beam, concentric ring, lack of sled rotation, low friction of heavy gantry/carriage movement (vs.sled movement) and parallel to work top chain are main contributor to such good results.
My work top is far from perfect - more than 0.5mm variation of hight (low cost chipboard - I am too cheap ;-)).
My next challenge is to get to below 0.5 mm accuracy in Z.
Stay tuned.
TomD
