Largest use of panel space

If you are going to be cutting the whole 4x8 rectangle, I recommend using a 12’ top beam. I have seen some posts where the limit is physical in nature. With a 10’ top beam, at the bottom corners, the cutting forces can be greater than the tension in the chains. This causes the chains to sag substantially more than what is captured in the firmware. When this happens, the sled position is uncontrollable. You end up with a rogue cut, where the sled wonders for a few inches.

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Ah yes, the wandering cuts. I really want to do a longer top beam and thought about starting off that way but decided to not push it and start off more standard and get that going well before venturing off.

One limit you might face could be (hope i remember this correctly) that there could something in the software limiting cutting over the dimensions of your sheet. Sadly until today, the user has no option to tell GC where X0/Y0 is on the sheet. It’s always calibration that tells me, so if that is off from the real world, the cut might not go to one of the edges.

Until today?

Yup, but there is light at the end of the tunnel.
We have have some crazy cool guys/geniuses/wizzards (i don’t know what to call them) working over the calibration and getting forward.

If you have the resources, a wider top beam will help on getting things well and trying forked firm/soft-ware has a good chance to give you a head-start compared to the standard. Check your dedication if there is a little room :slight_smile:

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Nice. Best place to find longer chain?

Stuck one this one :frowning: . Sold out on
and the new suppliers, from the little i know are focused on complete kits.
Direct message them and ask, because questions are free.
For other sources the US guys will hopefully help here.


Just for the likelihood from statistical data i made a assumption/guess that you are also in that region :wink:

Was this an effect that was partially mitigated with a heavier sled?


From what i’ve seen with the second heaviest sled was that it did, plus i could go down with the frame angle to compensate more.

yep, in the US.

How about this:


Spot on! ANSI #25, pitch 0.25" (~6.35mm) looks like the right thing!

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The connecting links are important. Additionally, you will have to press the pin out of the chain in order to break it. I was able to do it with a hammer and nail; however, it was difficult and frustrating. If you want to avoid the frustration, you will need a press.

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Yes. I believe so. However, you’d have to double the sled weight in order to get the same result, in terms of outward force at the bottom corner, as adding 2 ft to the beam length. Then you run into issues at the top-center.

If you know you’re going to be using the whole 4x8 cutting area, and you have room for it, I would recommend going with a 12 ft beam right off.


yeah, double weight is a hard sell. That said, I am sure there are others in the same position as I am where another 2 feet won’t fit.

For us, a somewhat heavier sled, slower cutting speeds in the lower corners, and, if possible with your CAM program, judicious use of cutting direction (I know there are threads related to this, but I don’t have time right now to search for them. If I can find them later I will edit) should mitigate most of the wandering.

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How cool is this, I had some chain at the house I had saved from junking an old processor years ago. I checked and its the exact chain I need! Not really a hoarder but I have some tendencies lol :wink:
Bog maslow here I come.
What is the preferential height of top beam for a 12’ beam?

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Am I going to be able to use the standard calibration instructions located here in the wiki since I’ve gone to a 12’ beam?
I was reading the linked post and its freaking me out a bit.

I initially used the standard maslow calibration (estimating left-right motor distance, top beam height, and sag correction factor). Then I had to cheat the Distance between motors because the top center positions were too low.

On my maslowCNC frame (11.5 feet top beam), I had to extended chains, and set chains length through GroundControl.
Here are my physical settings:
Distance between motors: 3501 mm (the real one)
Motor offset height: 618 mm
Extend chain distance: 2000 mm
Chain length: 3450 (that is what can go beyond the sprocket, but Ihave more behind it to connect loose chain pulling mecanism)
Rotation Radius 138.14mm (I use the ring kit)
Chain sag correction: 12

Now did you see the improved Holey Calibration beta test? If you do want to try it, I invite you to post your question on that topic.

This one will tune both chains tolerance, distance between motors, and motor offset height. It includes chain stretch correction and does not need chain sag correction (but you have to measure the sled weight and enter it to ground control.)


I’m not sure I’m computer savvy enough to mess with script.

Maybe you can post your initial machine parameters and measurements on this forum. I could run the script for you, and reply with the outcome.


Cool, thanks Joshua. I’ll work on it and let ya know.

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