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Tensioning system to improve performance in bottom corners

chain
tension

#41


#42

chain sag correctly didn’t change much at all (28.09 to 29.12, within the range of other measurements changing)

how much weight did you add to the sled? that doesn’t look right.


#43

10 lbs more


#44

hmm, I would have to dive into the math, but I would have expected that to make far more of a difference (especially based on how much the cut is distorted)

can you double check that you haven’t had a chain slip? do you see the error mirrored exactly on the other bottom corner?


#45

It’s possible that some factor other than chain sag is responsible for the skewing, or part of it. Rotation radius error causes bowing of the horizontal lines, too large a value bows downward.


#46

I’ll check the bottom right corner tomorrow morning. No chain skips. Both chains are measuring 1700mm when not connected to the sled


#47

rotation radius is identical, motor spacing only changed about 1mm, z offset only changed around .5mm


#48

I know this is a little late, but I am interested!


#49

Bottom right mirrors the error. I recalibrated with heavier weights again. Everything was the same except chain sag raised to 29. I added lighter weights and the squares are the same…not square. More weight does fix the L though.


#50


As you can see in photo, 90 degree cuts get progressively worse towards very bottom corner. Instead of adding more pulleys and counter weights, we decided to try extending 10 foot header to 12 foot first. That was the easy part.

First problem was the calibration process wanted to use a chain to measure distance between the two motors, but the chain was not long enough. Ended up manually measuring between shafts and entered 3632 mm in settings.

Then we ran the set chain length program and it measured out what it thought we would need for a frame of 3632m. But as you can see in the photo, the chains have a couple feet between them, not able to attach sled.

Before I spend the time to do manual calibrations and measure everything by hand, is it possible my old Kickstarter chains are not the same length as the new kits shipping these days?


#51

That step is for the 8’ frame. Use the ‘Next’ button to extend the chains the amount that will put the sled at 0,0 and you can attach the sled.


#52

the chains are long enough for a 10’ top beam, you need about another foot (possibly a smidge more) to use a 12’ top beam.

the chains shipped with the kit are 11’ long, 12’ long will work for cutting but to measure the motors you probably want a 12.5’ chain.


#53

EDIT: To clarify: it’s impossible to use a 12 foot header unless you also buy new 12.5 chains first. Let’s make sure NOT to say a 12 foot header is an option, unless we also say “12 foot header and new 12.5 foot chains”

After clicking Next, there is no option to Extend chains. I’m stuck.
During Calibrate, I Extend chains, it spits out default length. Press next, it asks to zero in the Z.
During “Set Chain Length Automatic”, I extend chains, it spits out default length. press Next and it says “Congratulations! Your chains have been set to a known length” and I checked Calibrate.
Also, attempts to press “Extend” a second time on initial screen results in motor making some noise but not doing anything.

(Sidebar: So far 12 foot header is good idea in theory, but doesn’t seem practical . If this isn’t easy for everyone, this route would not benefit the community. I don’t want a unique setup for just me.)


#55

I must have misunderstood which step of the calibration you were on. I assumed iot was this one:

I’m pretty sure that the ‘Next’ button should do the same thing as the ‘Move to Center’ button on that screen, extend enough chain to hang the sled at 0,0 based on the dimensions (distance between motors, motor height, rotation radius of sled) measured or calculated.
If your chains are still as shown in your picture above, the Actions/ReturnToCenter button. If the chains have been lifted from the sprockets since the chain calibration step, you could use the Actions/SetChainLength-Automatic button to run just that portion of the calibration sequence. Before doing that, though, take a moment to check Settings/DistanceBetweenMotors, Settings/MotorOffsetHeight, and AdvancedSettings/RotationRadius values.
If this doesn’t help, could you attach a copy of your ‘config.ini’ file from your home directory? All the setting values involved are stored there, and could help troubleshoot.


#56

Or 5 feet/1.5ish meters and a couple repair links


#57

I believe we removed the “Next” causing a move to center because folks weren’t expecting it to move then and it was causing concern. To get it to move to center you now need to click the “move to center” button


#58

Hey @ChuckC, I apologize. I have used a 12’ header. I forgot to mention that I had to purchase an extra length of chain, in addition to master links to connect them to the current shipped chain. I ended up adding about 20 inches to the stock 11’ chain.

It is not too difficult, but it costs $$ and takes about an hour of time. There are instructions online about how to break apart roller chain. You have to hammer one of the pins out of the chain. I was able to do it using a hammer, a drill-bit, one of the small nuts shipped in the kit, and a pair of pliers. Then you use a master link to connect it to the 11’ chain.

Given the results shown in this thread, I don’t see the default frame as being capable of cutting a full 4x8 sheet, no matter the calibration. The Maslow should be fitted with a 12’ top beam, along with appropriate chain lengths, if it is advertised as a 4x8 machine. This tension system or heavier weights are also options.


#59

It is not too difficult, but it costs $$ and takes about an hour of time.
There are instructions online about how to break apart roller chain. You have
to hammer one of the pins out of the chain. I was able to do it using a
hammer, a drill-bit, one of the small nuts shipped in the kit, and a pair of
pliers. Then you use a master link to connect it to the 11’ chain.

a chain breaker is about $15 on ebay, that makes taking one of the pins out
much easier.

Given the results shown in this thread, I don’t see the default frame as being
capable of cutting a full 4x8 sheet, no matter the calibration.

remember, different people have different tolerance for problems. slowing the
feed rate will allow you to give gravity more time to move things, and so it can
be made to work.

remember, there are people out there with the original maslow ‘winged’ frame
happily cutting away.

That said…

The Maslow should be fitted with a 12’ top beam, along with appropriate chain
lengths, if it is advertised as a 4x8 machine. This tension system or heavier
weights are also options.

I agree that this is a good idea (just don’t go too heavy or you have trouble at
the top)


#60

To go slightly back on topic,

@Jacob
What lengths of elastic cord and paracord did you use? Where did you source the elastic?
I’m building my frame with a 12’ top bar, I was thinking of using your idea but tucking the cabling above in a couple of troughs like so…

modjacob1

Think there’d be any problems if I skipped the paracord and made the whole length elastic?
My guess is that ideally, the elastic should also be mounted on a ring…


#61

Just looking at the design, it seems like some kind of tension needs to be present at all times to keep everything on the pulleys, so elastic everywhere seems logical. I am really interested in how this works, as I am planning on trying the 12’ top beam myself. Please keep us posted!