Maslow Mark II - 3D

What about making a post of some sort for each chain with a threaded hole in the top to insert a M2? The screw would fit into the empty hole of the last link and provide a pivot point.

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Wow, I’m seriously considering trying this for our Maslow. After all, we already have the rails for our panel saw option.

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I really like this idea and I will try to make my own version. Thanks for all the info.

I was thinking about making a design so the cutting bed is adjustable. Maybe bolts to adjust it in and out to help get it flat/parallel?

WB

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I’m a big fan of this design as well. I’ve been through the Community Garden / Github files and I have some questions and/or seek advice:

I’m in the US and haven’t been able to track down the “carpentry angles” you reference in your BOM. I looked pretty far and wide, even referencing the ‘DMX’ brand apparent in one of your photos: Can you please provide us with a little more specification or description of those elements?

I noticed that the Fusion & STL files have a slightly different design for the ‘Carriage Bracket’ than is shown in your photos. Looking at the STL, I see that the printed element has thread that might take an M8 screw… I have to say, I prefer the design from your photos that doesn’t rely upon a 3D printed “nut” to fasten into. I’m likely capable of making this change to the design myself, but I’m curious why you changed the STL from the “as-built” bracket.

Until you proposed this strategy for a frame, the conventional wisdom in this forum had been that additional accuracy could be gained by extending the distance between motors and, to some extent, the distance between the top corners of the work surface and the motors. Achieving 0.5mm accuracy across all points of a 4x8 sheet of plywood is good enough for me, but I wonder if you have any insight or can speculate on whether or not your design could be improved by increasing the distance between the motors and/or the distance of them to the top corners of the working surface.

My last question is to simply ask for additional detail on the strategies you used to allow adjustment of the elements, especially gantry’s rails. From what I can tell from you photos, you have bolts to adjust the rail in the Z axis. How many of those did you use? Where did you place them?
Did you implement any strategy to accommodate the Y axis?

I ended up quickly building a sketchup model that combined the ‘bracket’ Fusion file and the table drawings… simply to get a better idea of the assembled … assembly. I’m happy to share it, if it seems like it could be useful.
Let me also say that my Git skills, while lacking, might just be enough so that any progress that I make toward elaborating instruction on how to build a TomD frame could be merged into the Master, if you’re willing. Please let me know and I’ll assure that any changed I’ve made and will make are tracked correctly by Git.

Best wishes,
dugan

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going to a coreXY drive would give you far better than 0.5mm accuracy, without
needing to go any wider than ~9 ft (6 inches off each side for skirting)

using motors on the top corners to move the sled will cause you to have to fight
with all the inaccuracies and still deal with the min/max force issues, needing
a wider/higher top beam to get better forces inthe corners.

David Lang

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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On the contrary, the comment I quoted comes from one of the most brilliant entries I’ve read. In your wonderfully imaginative iteration you have still managed to encompass the true simplicity of the Maslow CNC. Very eloquent.:trophy:
I nominate it for “The best of Maslow”.

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Thank you @TheMerryYeoman for your kind word - I appreciate it

wrong recipient - how to delete post?

Dugan - check this out https://www.amazon.de/dp/B01N4AJHA3/ref=sspa_dk_detail_8?psc=1&pd_rd_i=B01N4AJHA3&pd_rd_w=pTnQY&pf_rd_p=00903874-3af0-47e0-8622-ee58087f71cf&pd_rd_wg=D4eMN&pf_rd_r=R5QNHJWXDFJ0P7CZA1VM&pd_rd_r=fb17ad65-7496-11e9-bd09-6b265a2d278b
and this
https://www.amazon.de/GAH-Alberts-333584-Sparren-Pfettenanker-links-sendzimirverzinkt/dp/B008KGADTO/ref=pd_rhf_dp_p_img_4?_encoding=UTF8&psc=1&refRID=T0A45FF3DYZ6SK7S923X

as far as angles go, take a look at the unistrut angles

especially P1956 P1957 and P2484 and P2484W

By sticking with the ring, this design doesn’t eliminate many of the possible
sources of error. A stronger top beam/frame will impact the possible error from
top beam flex. The gantry eliminates variability of friction (while adding
possilbe addtional friction if the gantry tries to rack due to the asymmetric
pull on the sled if it’s at one extreme)

I would not have guessed that the gantry improved friction enough to apparently
counter the racking issue (which shows why people should try, even if ‘experts’
like me provide discouragement on theoretical grounds :slight_smile: )

going to coreXY will eliminate the error due to chain stretch (the chain is
under pretty stable tension continually), sag will be less of an issue (the sled
is much more contrained), gravity (and therefor top beam length) will no longer
be a factor, frame tilt will be far less of a factor (and if the sled is
prevented from lifting out of the guide would be a non-factor), the ring
dsappears entrely, and probably a few more benefits that I can’t rattle off
immediatly.

But a workng machine trumps all ‘it could be better’ arguments :slight_smile:

David Lang

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There are going to be versions of these sorts of things available at any
lumberyard (the big box stores will have some, but not all of them), but these
are all designed as reinforcements, to hold wood parts together with lots of
nails (they are designed so that you have a nail in every one of those holes),
and their purpose is to hold the boards in place, not be structural in
themselves.

the unistrut angles I postedabove are MUCH heaver, either 3/16" or 1/4" thick.

David Lang

Dave - what do you exactly mean by “coreXY”?
Tomasz

it’s a way to drive a gantry machine where the motors are stationary (and if you
arrange it properly, you can make it so there are no mechancal parts below the
workpiece for the sawdust to fall on)

https://corexy.com/theory.html

look on youtube for the Ant PCB mill for a small CNC designed for cuttng
PCboards that uses coreXY and includes good videos on the assembly that show the
belt/chain routing.

David Lang

Is that a rolling calliper?

It is my modification of ordinary calliper. As long as tape and calliper are in the same units vernier still works but I can measure long distances with vernier accuracy. Well almost - keep in mind that tape is not as tight as slider and it is easy to miss-align and screw the measurement.
I do not know what rolling calliper is - I just bought cheap Chinese typical one; unscrewed slider and replaced it with tape.

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Thank you Dave - interesting!!!

Thanks to all for your helpful replies!!

TomD that is a sweet caliper modification.

I’ll check back in when I’ve had a chance to absorb all that you guys have relayed and made some progress on my build.

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In case you missed it, that inspired me to make a 3d printable version, see

David Lang

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Tape calliper would have been a better translation, in dutch we say “rolmeter” rolling measurer.
Keep in mine that the accuracy of a tape measure is quite low, a class II has almost 2 mm possible fault per meter, so while that calliper gives you good resolution, it doesn’t give you reliable accuracy. 0.05mm resolution with 2mm accuracy doesn’t make sense
http://www.pewa.de/DATENBLATT/DBL_CT_BANDMASSERSATZ_DBL_DEUTSCH.pdf if you want to know about precision ask a german :slight_smile: