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Gersus’s build log


#1

I want to start this thread to document my build/projects and keep it all in one place. If there is a better place for this plz move it.
This weekend I bought a Ridgid, and built the default frame and temp sled. Ready for my kit to arrive tomorrow! Let me know if you see something that looks like it might give me some trouble.


#2

If I may, (& If it’s not too late) I wish that I had cut my sled with vertical grain as it would glide easier on the typical horizontal grain of the work stock. Hope to help! :grinning: Everything looks great to me so far, You Rock!


#3

Question - is this small bungee cord still the preferred cord to use?


#4

Is does the job to an extent. But if you plan to run the slack chain over the top beam, it’s not recommended.
My recommendation would be to go for a weight tensioning, as that has a constant force on the chain, independent where your sled is on the sheet.

Edit:
There are much nicer ideas for weight tensioning here in the Forum, but an ugly prove that it can be done with the roll-bearings from the kit is here: Poor man weight chain tensioning


#5

Thanks Gero!


#6

Great post! I went to our local little hardware store and I think this will work well. It clears the too beam well.


#7

Nice job! Much cleaner then mine!
You don’t need much weight, ~2kg per chain (~4.40 pound) should be enough.


#8

Thanks! The pulleys are meant for a garage door. Even have a nice smooth bearing in them.


#9

One more tip. Can’t tell for sure with the picture, but it looks like the slack chain ‘aligns’ with the metal motor mount. If the chain feeds from the side to the sprocket, you risk chain jumps. Easy fix is to add a spacer under the fixed side of the chain and under the small pulley to bring them out same distance as the sprocket.


#10

Can you post a pic?


#11


image


#12

I see what you mean now. The chain needs to stay on a plane parallel to the motor sprocket. I think my setup is good.


#13

Frame built, temp sled built, motors mounted and counter weights done, arduino firmware done, GC installed, makercam and CAD software played with. Time to calibrate! Probably this Thursday… hoping it goes well!


#14

Oh, still need to install z axis… and I can’t find the screws to attach the motor to the L bracket. :roll_eyes:


#16

Opted to go 12’ beam based on discussion in another thread about accuracy cutting full sheet.
12’ beam installed, longer chains attached. (32” added) too long, I’ll have to figure out just how much too long. Maybe it’ll reveal itself during calibration?
Cables to the motors arent quite long enough now, guess I’ll mount the arduino on the top beam.


#17

I suggest to flip the chain on the pulling side so there is more wraped around the sprocket.
Here is a close-up view around my motor, using the nylon tubes as rollers to let the chain find itself the alignement.

(You can see that I also adjust the amount of slack with a hook.)


#18

That looks much better then standard :wink: , solid and clean.
It has a bit of a japanese gate!
Make sure the motors are level. I used a clear tube filled with water that i estimate to be +/- 1mm accurate over 11.5 ft distance.
image
Also level the top of the sheet.
I’m not a fan of cutting the ‘final sled’ with a questionable calibrated Maslow. Many others did and where successful. My first sled i did by hand with a simple router circle jig.


I put more trust on my measurements then on a machine that i’m still going to make more accurate.
The second and third sled i cut on my desktop cnc to be sure that things are aligned they way they should be. Alignment of the router bit and the ring is not to be ‘under-looked’. (sorry for my ~english)
A rounding bit for the bottom of the sled and some wax and your good to run a cut.
Hope the “build log” will continue as a “cut log”.
Keep it coming :slight_smile:

Edit: If those 2 top-beams are stiffly connected, you have already decreased the amount of expected flex by ~ half. Respect.


#19

I hope this becomes a cut log too soon! :slight_smile:
The 10’ beam is very stiff. Stacking the 12’ on top I thought would be very solid but it turns out the extra distance really compounds any flex. It’s still solid, with most of any potential flex being forward/back if that vector makes sense and probably not the primary force vector placed by the motors. I still may add a kicker on the back to stiffen the out two feet.


#21

IMG_7866

Here are my results after the normal calibration.


#22

You have a ring kit. Rotation radius is 138.14mm.
The Sag correction for my 11.5 feet is 16. I think yours is ok too. This is not a very sensitive value.
Now you want to measure ±0.5mm your top motor (sprockets center) distance across the beam.
Vertical motor offset: enter your own measurement ±1mm is a good precision.

Now you should measure your total sled weight (everything hung at the chains tips) ±1 lbs.

And here you have two choices:
a) you fake a shorter motor distance ( a few mm shorter than real) to avoid the top center dip. That dip squashes vertical position for y>0, more as the sled gets close to the workspace top edge.

b) A new firmware update is expected soon. This will include chain stretch compensation to avoid the dip, using the sled weight value, and should work fine (I’m checking it out) with the new 6 point Holey calibration to help you accurately find your chain tolerances.