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Who's afraid of BigMaslow?

Hey, I’m creating this thread for people who have working “larger than default sized” Frames and to discuss the particular advantages and disadvantages of such designs.

It’s been speculated by myself, and others, that a wider frame (somewhere in the 11-14’ range) will make the bottom corners, in particular, more accurate across the full range of the (4x8) workpiece and greatly reduce the errors seen by low chain tension.

Please share your experiences with any ‘larger than normal’ machines.

My own frame is 10’ unistrut but I’ve attempted to compensate by limiting my workpiece size to 6’ width. Unfortunately, after motor mounts, I actually ended up at final width numbers not terribly dissimilar to the wood frame. Also I’m limited in my current machine placement, and will need to reconfigure a significant portion of my shop/garage to accommodate a larger frame, but I’d like to see what others have found if they have larger designs in place and running.

cheers,

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I’ve ordered a 16’ piece of unistrut for my frame. I’ll be starting on that in August so I’ll be able to contribute to this topic soon.

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@Dustcloud had a great idea (although somewhat cumbersome to manage at times) to offset your work piece on the frame as shown here: https://aws1.discourse-cdn.com/standard11/uploads/maslowcnc/original/2X/e/e7871b97a389a1d306342c7b51d6d2ca2eaffafa.JPG

This is a quick fix to get better accuracy in the corners of your 4x8 sheet - you’ll just need to break up your cut and files so you can move the board over half way through.

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does 3430mm ~11 1/4 foot motor distance and 491mm ~19 1/3 inch height to sheet count? :thinking:

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Probably, but not by much! =P

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I like working with projects that are on the full plywood sheet scale and I am on board with this!
Just got my kit and I am setting up the temp frame situation to get going right now but will go big with some fat aluminum channel I have ready and waiting for just this application!

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Got my kit yesterday and downloaded the firmware and ground control without too much hassle last night. The frame has been mostly built for a month and a half since I ordered the kit. I wanted to be able to hit the ground running. Originally the frame was Bars design but after reading the forums i decided i wanted a 12’ top beam and have that 2 ft above the work space. So i bolted extensions into the A frames and bought a 12 ft 2 x4. The original 10 ft 2 x 4 was screwed to the bottom to straighten it out and add some rigidity. As you can see the motors, bungees, and chains are installed. I’ve got 10 more ft of chain on order that’ll get here in the next week but I’m wondering if maybe i ought to move the bungee attachment point inboard maybe a foot on each side? I know there’s not a lot of experience yet with a 12 ft top beam and if someone has commented on the bungee system i haven’t seen it.

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I’m building my 12’ frame at the moment as well… remember you’ll need some sort of featherboard around the edges to use full sheet so the plate doesn’t tip off… I’m putting my featherboard on slots so I can adjust for minor variations in board thickness.

Yeah I’ve been thinking about that. I’ll also probably start adding in supports at other points to make the whole thing more rigid. I realized that my spoil board is much too nice a piece of plywood to get carved up that way so I’ll get a cheaper piece and have my first sheet for when I’m ready to make something nice.

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Hi, I’m interested in making one that supports 2140m x 2440mm melamine sheets because I work in melamine.

What I understand is that you only have to change the length of the chains and the separation of the engines.

If I’m not wrong when calibrating the motors the system asks for the size of the work area.

tell me if I’m wrong or I’m missing something

I’ve got to say that sounds like a monster of a sheet to handle!

I think you will have trouble with that geometry, particularly in the bottom half of the sheet. With the motors at least 450mm above the top edge of the sheet, the chains will have very little sideways pull when the sled is down near the bottom, and that will affect the accuracy.
?

I just finished my frame, Maslow still not arrived, although it is in the country! I built the default frame as per the instructions.

One of the main things i want to do with my Maslow was to make full size arcade cabinets, so needed a full 4 x 8 work area. So after some reading, i decided to move my motor mounts up and out. I had a bunch of leftover wood from building a deck, including a 10 x 12’ beam. I figured mounting this right on top, and bracing up the supports would move my motor mount points up by ~9 inch and out by 12 inch. I luckily have 11 foot ceiling in my Garage so this ended up like this:-

Hows this look?

Also I have a 14’ high by 12’ long wall in my garage. I was thinking if i could do a 8 x 8 work area having 2 4 x 8 in portrait next to each other. Might be a fun experiment, although probably an expensive one. Anyone tried this before or is that just too big?

Edit - I know i still need to add some boards around the edges to support the sled to cut to the edge too, figured id wait till i have a working maslow before worrying about that, as I have no leftover ply… heh.

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If you are looking to build an oversized maslow, you really should grab a copy of the spreadsheet and tinker with it (sorry, inches only currently)

for a work area of 2140m x 2440mm (85x96") going to a 12’ beam and raising the top beam by 4" will result in forces that are better than the stock maslow in all locations

David Lang

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@dlang Wish there was a net 12”x4” L type rectangular tube bracket that could easily be added to each side of the unistrut. Just dont think Im ready to deconstruct my frame yet. Would love to go edge to edge in all corners with accurate cuts, but for now Ill just keep movin ply to the sweet spot.

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Thanks, I Just finished putting everything together and cut the final sled. I know my calibration was probably way off, need another pair of hands to properly measure alot of stuff, especially when i cant reach the motors without a ladder… heh. But i can report even with my presumably ‘bad’ calibration, the final sled cut was 18’ exactly across and like 17.9 high. Spent some time on it with round-over bits, sandpaper and the 3D printed vac attachments I remuxed from the ones on the Garden. Came out pretty good i think. Deliberately went to lower left as far as i could to do the cut.

Also got the auto z homing using a $12 sheet of 16 gauge steel and spindle / vac power on/off using aux 1. Trying to think of uses for the other aux pins. Couple ideas i had, no idea if they would work or not?

  1. Thermasistor mounted above spindle, trigger an alarm if for instance the temp shoots up in case of a flame? Know machines like this should never be left unattended, but would think in the event of a flame up, the resistor would shoot up and trigger an alarm pretty quick. More of a ‘hey look over here’ alarm then anything meant to leave the thing unattended.

  2. Depth gauge / gauges mounted as close to the spindle as possible, maybe just outside the housing. either using a proper depth gauge or even just a micro switch to detect sled lift. Know there would be issues when it goes over material that is already cut, but just spit balling here.

  3. No idea if this is possible either, but maybe a mouse sensor for tracking actual movement, thinking more ir or laser then old ball one. Can forsee issues with this as well with depth of material already cut and sawdust though. And of course the sled rotating as it moves.

No idea if any of these are any use or have been suggested before, but putting them out there for people with more know-how with the Maslow then myself in case they have not.

Question about the motor spacing, is there a magic ratio between height and seperation? I went up 9 inch and over 12, but you mention going up only 4 and over 12? so it is 3:1 or is the bigger the better within reason ok, regardless of ratio?

AUX5&6 are both Analog inputs on the current PowerControl board and the TLE5206 board…

So that means they could read a Thermasistor? Or a light-sistor thingy? Drawing a blank on its name right now in the case of a lift sensor? if it sees light the sled is probably lifted? Also spelling it seems…

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It does - a thermister or photoresistor, or a whatever-sistor.

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Hi,
I’m planning to order a Maslow around month’s end, so naturally I’ve been reading and scheming. My thoughts on mechanical ways to retain the Maslow concept while improving the 4x8 precision are to:
–replace all the non-vertical chain with heat-set pre-stretched spectra (dyneema). I’d move the motors to the bottom corners, and run the chain purely vertical, eliminating most chain sag, as well as “plucked string” movement caused by sudden tension changes.

–grow the frame to improve line geometry to the whole working surface. I’m planning a 14’ top beam, 3’ above the ply top.

–to make light 3d work possible without worrying about sled support, i’m considering mounting my non-sled to a pair of roller-coaster track kind of pipes, that in turn are mounted to a pivot at the center of the top beam. The pipes/sled tracks would then ride at their bottom/outer edges on 1x3’s mounted on edge around the work surface. In an ideal world, I’d learn the firmware language and add polar or radial kinematics support for the firmware, and use a single point attachment since the pivoting rails prevent any localized sled rotation.

I can’t post the drawing here directly, but here’s a dropbox link if it helps.
Frame pdf

Now somebody tell me that my ideas have been all tried before and rejected, or that it’s not a Maslow if it doesn’t slide on the workpiece, or that mechanical solutions are all best “just handled by the software”! :grinning:
That is to say, criticism gladly accepted!
-Chad

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–replace all the non-vertical chain with heat-set pre-stretched spectra
(dyneema). I’d move the motors to the bottom corners, and run the chain purely
vertical, eliminating most chain sag, as well as “plucked string” movement
caused by sudden tension changes.

you don’t have enough vertical space to have enough chain, and your spectra will
still sag, so you haven’t eliminated the problem, just changed it.

we have chain sag pretty much taken care of in software, so there’s not much to
gain from this.

If you could eliminate the chains entirely and go to some other line on a
take-up reel (especially if you can measure the movement of the line instead of
the motor) you would have a win.

–grow the frame to improve line geometry to the whole working surface. I’m planning a 14’ top beam, 3’ above the ply top.

this is good
min force 7.64 pounds, max force 24.88 pounds (stock 3.26, 33.74)
you probably don’t need to go nearly as high 26" above would be 8.38, 33.09

–to make light 3d work possible without worrying about sled support, i’m
considering mounting my non-sled to a pair of roller-coaster track kind of
pipes, that in turn are mounted to a pivot at the center of the top beam. The
pipes/sled tracks would then ride at their bottom/outer edges on 1x3’s mounted
on edge around the work surface. In an ideal world, I’d learn the firmware
language and add polar or radial kinematics support for the firmware, and use
a single point attachment since the pivoting rails prevent any localized sled
rotation.

I’ll say what I’ve said many times before, if you want a rail system, go with a
corexy setup and you will be much better off. you would eliminate all the ugly
math and dependence on gravity as a force and have a fairly conventional CNC
machine.

sled rotation doesn’t matter, so don’t go to a lot of effort to eliminate it.

these rails will add a lot of extra weight to move, a lot of extra friction, and
a place for sawdust to accumulate and affect things.