Calibration trouble!

Hey gang! I have had my machine for a while but only recently had time to get up and running. I have spent my Labor Day weekend trying to calibrate and get up and running. I have several questions but firstly a dilemma. I worked through the calibration process in Makerverse (as well as I could. I think that maybe some of the instructions are missing :man_shrugging:) and made it all the way to the last tab to run “cut,” calibration. My home position wasn’t perfect and was hitting probably -1/2", -1/2" but I figured I coul

d sharpen my aim later. Anyway, as I run my calibration cut to the bottom right quadrant, I noticed that the groove turned downward. Before I could click the stop, the left side chain nail was ripped from my top beam and, naturally, the sled dropped. I jerked the plug on the router and DUE. The nail bent pretty bad and the head broke off. So, a couple of things:

#1 The nail-What is the diameter and type of nail used? Where can I get more if I can’t find them at the local hardware store? Also, would it be beneficial to replace it with a screw or something?

#2 The cause of the problem- Any idea why this happened? I had ran the normal calibration just before. I had my soft limits enabled. The bit hadn’t even reached near the end of the board so, I’m not sure that overextension was an issue.

Thanks so much for any help anyone can offer. I really like this machine and I’m not quite discouraged but I have hit several walls so it is time to reach out for help :sweat_smile:

It just needs to be small enough to fit in the end of the chain, other than that pretty much anything will work. It’d be hard to find a screw that’s the right size, but if you can find one that would work also.

My guess was going to be over extension so you’ve got me stumped :grin:

Thanks for the feedback! I’ll tack it back together and try again. Maybe the chain dragged it off or something. T

This is the pattern it managed to cut. It’s kind of funny looking at it after what happened :joy:

the grove turning down like that indicates that the chain being fed out from the left stopped moving. If it ran out of slack and/or caught on the nail, that could account for the problem.

Good call! That makes sense because the right side motor would still be feeding chain and allow it to make a clean turn downward. Meanwhile, the left motor is trying to continue feeding slack but, since it was close to the end of the chain, it dislodged the nail. That makes perfect sense! Any idea where to begin looking for the issue? I suppose I could reassemble the chain and start back at chain calibration, right?

the issue is the nail holding the chain was too far from the motor and got yanked out. Are you using a 12’ beam? if so, did you get chain extensions for that extra beam length? If not, the nail was just placed about 6 inches too far away.

I would reassemble the chain and then extend it manually and see what exactly is
binding up as you get to the bottom corner. is the slack end of the chain too
far from the motor? does the slack chain management catch on something? some
other problem?

by moving manually (in smaller moves) you can se as things are getting close to
being in trouble rather than havng things break.

David Lang

It is a 10’ beam. Actually, it is cut exactly at 120". I placed the nail per the assembly instructions but, that definitely sounds like a reasonable theory.

Good idea. Maybe I will put on a bump cap before as well. That spring is no joke! :joy:

I’m having the same issue, I got the complete M2 kit a month ago and started builing it as per the pdf in /pages/m2-resources. When reaching the bottom corners for the “precision” step, I ran out of chain, the mobile sprocket reached the nail and it ripped it out.
What I’m trying now is lifting the bottom skirt a bit (about 4 inches) and moving the nails 1 inch closer to the motors and moving the motors 1 inch closer to the center of the beam. I tested reaching the bottom corner of the board (minus the rotational raduis) in diagonal with the chain without the sled and it seems to just about reach fine. I’ll retry the calibration today and see what happens.

Does someone know what’s the max leght that the spring can be stretched without stressing it?

I’m including some images to show what I was talking about:
These are the 4 inches I was going to gain from lifting the bottom skirt:

This is sprocket meeting with the nail brfore it got ripped out, you’ll notice the color is differente, cause I already had to replace the nails due to a prior issue with the chain alignment, the width of the nails is 2mm by the way (see this post: Chain motors spin at different speeds during Y axis movement )

first off, springs or bungee cords provide the most tension when you want the
least tension, and the least tension when you need the most tension. weights are
much better (they at least don’t increase tension when it’s harmful.

how long are your chains? On my system (10’ top beam, 11’ chains) the ends of
the chain on the nail need to be much closer to the motors, basically with just
enough room for the sprocket as it’s reaching the far bottom corner.

David Lang

I like the weights idea, do you have a link or something to get more info on how to do that?
I’m terrified of the idea of the nail snapping again and getting whipped in the face by the bike chain, which I’m assuming is painful to say the least.

one example is:

many people have posted versions that use pullys and put the weights behind the
machine. I was lazy and left them out at the ends

this doesn’t solve the problem of running out of chain and tearing the nail
loose, you have to get the nail close to the motor and move manually down to the
bottom corners to make sure you don’t run out of chain.

David Lang

I have seen pictures of the set up with weights. That is a good idea. I saw someone attach what looked like 5# aerobic workout weights to the chains somehow. I guess that the overall goal is just to provide some form of resistance that will take up the chain slack as the machine moves around, yeah?


In the worst case (cutting at the far bottom corner), with a 10’ top beam, there
is less than four pounds of tension on the chain from the sled. If you pull on
the slack side harder than that, the backlash of the geartrain affects your
position and you aren’t exactly where you think you are.

the maslow uses a pully (in the picture I posted, you see a cloathline pully
that I use intead of the sprocket and s-hook, can’t go flying), so the weight
can be double this minimum tension, so up to ~7 pounds. what you want is the
least amount of weight that controlls the slack of the chain to keep it from
interfering with anything and keeps it aligned so that it feeds properly.

I just used a length of paracord attached to the cloathsline pully and a length
of electrical conduit sweep to redirect the line, cheap, simple, and nothing can
come loose.

David Lang