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Maslow Mark II - 3D


#1

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.

  1. Rigid and level frame.
  2. Motors and ring on the same level as centre of gravity so chains are parallel to work surface.
  3. Concentric router bit and ring axis; removing ring flexibility.
  4. 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 with AEG 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


UniStrut Frame designs
#2

I’d give it two likes if I could


Mod so sled does not ride on cutting surface
#3

Just wow!


#4

Love seeing another tube steel frame! Good idea to use self-tapping screws, much easier than weld everything together like I did. Keep up the good work!


#5

Excellent work, I would like to se a video of it working, keep going


#6

I second that… especially cutting something 3d :slight_smile:


#7

Great design and built! Will borrow some of that if i attempt an X/Y Maslow.
I screams for a pannel-saw exchangeable sled.


#8

Well done. This is the eloquent manifestation of what I was trying to convey with my “Nick Offerman” post.


So excited to see this!


#9

Fantastic! You mentioned boats, will you be making foil shaped rudders etc?

Would love to see a video and some more close-up pictures, great work!


#10

Thank you @USA1181 - yes my old sailing boat waiting for restoration, my daughter needs SUP and I will build second rowing boat for myself. I need time! So many projects…
…look at this Why I need Maslow - skiff and SUP
Cheers
Tomasz


#11

Thank you guys for kind words…
Watching cnc video is boring like watching paint to dry … ha ha ha … but if you insist ;-))
Sorry for raw video but I am not cameraman and I do not know how to edit clips ;-((



New challenge emerged: classical Maslow is forgiving for uneven worktop surface - sled just follow “peaks and valleys” and cut is relative to local depth. In my design Z distance is relative to gantry and flat worktop and parallel to gantry is a must - and that is the challenge ;-((

#12

Hi @TomD, do u have plans and material list for building it, I’m really interested in building one


#13

Hi Allan,
I do but not in the presentable form - a lot of hand drawings and notes; a lot of changes and experiments as usual with prototype. I have to reverse document “as build” without all “bugs”.

I do have gantry and carriage brackets models in Fusion360 f3d and stl format which I can share with you. I am in Poland so everything is design in metric. You should find steel profiles 40mmx40mmx2mm and 40x40x3 in your local steel stockist. If not then you have to redesign brackets and beams to inches and feet.

If I found time and generate plans I will post it in Community Garden - two pieces you already have Ring alignment and z-axis.

Ring and bit alignmentSimple pattern to align ring and router bit and reinforce ring mount

z-axis for AEG routerModification of AEG router

You can also find pictures of my old Maslow build to illustrate why I decided to build a metal frame - I need accuracy and precision and ease of material handling.

https://forums.maslowcnc.com/t/why-i-need-maslow-skiff-and-sup/6260/11?u=tomd

Cheers

Tomasz


#14

How well does it operate at the sides? It looks real smooth operating in the middle… :+1:


#15

No difference - when I cut test file (depth ~2mm) squares cutting goes as smooth as what you have on video.
There are no rotation of the sled and very little friction on bearings. My carriage/sled is quite heavy 5kg of lead and 3kg of router and ring so I have good tension on the chain. Everything is inclined 15deg so only fraction of weight pushes against rails (perpendicular to work space component) - rest hangs on chains and unfortunately - SPROCKETS. This is the weakest link - how long it will last.
With carriage/sled in the upper part of work space we have weight of carriage times tangent of angle between chains!!! Thats a big force for small bearings at the motors. It worries me.
The horizontal beams on which gantry hangs, takes only weights of the gantry; gantry is pushed towards workspace by perpendicular component of router/lead/ring weight and parallel component hangs on chain. We need that component to be reasonable strong to minimise chain sag, but we are paying prize by overloading sprockets bearings ;-((
The results of such force distribution is frictionless (well almost) X-Y movement but overload of motors.


#16

Wonder if you can make a sprocket block to spread the force on the bearings.
?


#17

I know this might be a known concept.
Seeing that your frame creates a gantry of sorts,
Can that gantry have mounted the Maslow motor system and occupy that gantry area only to mill that area or sector?
Either manually or some simple force for a given time of operation have that gantry occupy an overlapping section to stitch the project over the 8 foot length?
Like a panorama photo stitch.
Wondered if this would improve the accuracy .


#18

Thanks for the info I’ll try to build it


#19

Allan
This may help - dimensions of the frame.
table Drawing iso v2.pdf (78.3 KB)
table Drawing top v3.pdf (96.8 KB)
table Drawing side v1.pdf (103.7 KB)
And additional more detailed pictures;
Start with even and level surface; clamp before drill ;-))


Adjustments of beam linearity; my local friendly mechanic welded nuts to the beams;

Lower carrying gantry beam can be adjust to be parallel to top beam

Adjustment of the frame so workspace is not warped (wheel at the bottom is just temporary help to lift frame by one person - not very good idea - discarded later). Later on I replaced 2x4 support with 40x40x2 steel profile.


2 x 4 (as a matter of fact 34mm x 70mm) adding stiffness to workspace

New and improved, high tech flatness measurements ;-))

Details of carriage

…and gantry.
The sequence of steps in construction is very important:

  1. set top beam level
  2. make bottom beam parallel
  3. Adjust hight of gantry to resulted distance between top and bottom beam
  4. Construct carriage and adjust width of gantry to result distance: use shims to minimize tolerance. I was able to be close to zero with negligible loose. If satisfied tight all screws.

    You should end up with ~40mm hight

    Have fun!
    Cheers
    Tomasz

#20

This is great. Love the effort to reach that hallowed precision. Good luck!