Hi Dugan,
Happy to hear that you decided to build Maslow - Mark II. Please keep me posted.
“carpentry angles”
German made by Alberts Gmbh 30x140x2mm - left and right. I promise to pop up next week to my metal stockist to find out more and let you know. For now here is a picture of the label
"different design for the ‘Carriage Bracket’ "
Good eye Dougan… ;-)) I experimented with couple of design and found that design with screw (which you like) is the weakest. I broke two of them. I had to reinforce them so using threaded hole was natural solution. The latest version is even thicker (see Maslow Mark II - circular saw adapter ) The pilaSupport.stl is universal - no more left and right.
“frame”
I built two Maslows: clasic wooden and Mark II. In my opinion focusing on the issue of gaining accuracy by spreading motor distance and making table bigger is misguided. You can gain much more by making table rigid and aligning sprockets, sled, ring with centre of gravity of sled. Just by doing this in Mark II I made a leap in accuracy versus what I achieved with wooden frame (excellent discussion on accuracy on the forum). Here is an example: I cut profiles of my new rowing boat from 3mm 4x8 MDF - first picture gives you idea where profiles were located and second picture shows you a details of the parts which should be 484.5mm long, aligned on one end.
and second picture
As you see most parts are within 0.2mm with one outlier 0.8. My effective cutting area is 1129mm x 2395mm plus router bit diameter. You are not gaining a lot increasing size of the table but you multiplying problems with flexibility, handling, etc. In Poland metal beams comes in standard 6m length (19’8") so 3m is perfect - you not wasting any material. I am sure that US/Canada have the the same standard so choice is easy. My advice - 3m works for me, should work for you.
Think through twice how you will attach top beam (with motors) to the frame. The length will be established once you will find centre of gravity of your carriage. Look how poor job I did - we should establish “Rotten Tomato Award of the Week” and picture below illustrates first candidate. ;-((
“adjustment of the elements, especially gantry’s rails”
Good question! Legs adjustement works fine - I strongly recommend thick (40x40x3mm) support beams (those attached to wall and floor) Mine are 2mm and I see a little of movement. The same with horizontal X beams. My screws for Z correction are welded just in the middle and pushing against 40x20x2mm beam. But X beams sagging VERTICALLY so much better will be support illustrated on next picture. ( I am holding it by hand just for illustration - fasten angle on one side and simple nut and bolt from the bottom will give you adjustment up and down. It is too late for me unless I will disassemble whole structure - no way Jose!!!)
Also 40x20x2 is way too flexible. Top and bottom horizontal beams should be 40x40x3. It has enough rigidity to hold gantry. Buy only high quality beam and hand pick from yard watching how straight it is.
As far as Y axis is concern I am a little like “deer in head light” I have no bloody idea how to bite this challenge…
If this is the challenge at all…
Imagine distorting whole table - squash two opposite corners but keep top and bottom beam parallel, squash gantry and carriage the same way. Gantry and carriage can still move freely although local XY of table/gantry/carriage are no longer orthogonal.
What Maslow’s software see? What happen when Gcode commands to cut a vertical slot? Will slot be vertical?
That’s the beaty and elegance of Maslow design - source of error is only one: the length of chains. Slot will be vertical - gantry and carriage only supports router. This is just different type of sled - nothing more. I need exactly horizontal top beam ( the one with motors) so gravity works with me and left and right chains are stretch correctly. I need top beam supporting gantry to be horizontal to minimise forces for gantry movement. I really do not need lower beam supporting gantry to be horizontal as gantry just roll over it (making it horizontal minimize friction of gantry movement).
So adjustement of Y really does not matter and it is enough to rely on gantry bracket to keep it square.
Z accuracy is separate issue and lets put this thread on the back burner - I need a truly 3D project to gather more data to have a meaningful discusion.
“sketchup model”
By all means - please share with us your experience. Everybody will benefit - riding on ideas is best way of solving problems. The most efficient method of discovery is “try and error” and no better way of verification if idea works is to build and see what others are thinking.
Pleas keep me posted and I am keeping my finger crossed for you successful build
Cheers
Tomasz
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