Is the feedrate for Z-Axis hard coded? (solved)

Testing my new c-beam z-axis I put 2 commands on the marco buttons.
makro 1: G0 Z10 F800 makro2: G0 Z0 F100
Both commands take 3 seconds to move the 10mm :frowning:
Yes, I have a pitch of 10mm now :slight_smile:

Edit: GC/FW 1.25
Edit 2: F1 makes also no difference, so feedrates for Z are entirely ignored or not implemented?
Edit 3: Found part of the answer here:

Edit4: Further digging showed that F is ignored for G0 (max is used) but works for G1.

Remaining is to figure out how to adjust the speed to match feedrates in g-code.

Full success! (Disclaimer: This are the setting for my particular c-beam! Unless you have the exact same hardware, do nut use this settings!)

Changing the $18 to 20 instantly gave me the expected results. With a possible travel of 72mm I’ve chosen 60mm travel for testing to stay away from the ends. F60 takes 1 minute for 60mm, F120 30 seconds.
Above it seems not quite linear because to get to 20 seconds I need to use F188 instead of F180 (21.5 sec).
The error is small enough to ignore. With $18=20 and a pitch of 10mm the max speed the standard z-motor will move my Z is 180mm/min = 3mm/sec (translating to F188 in g-code).

For those wondering how I got a pitch (actually lead) of 10mm:
The c-beam has a lead of 8mm (2 mm pitch x quadruple thread = 8mm). I’ve ordered a bunch of ‘Teeth Timing Pulleys’ and belts in different sizes. Although I did order a idler pulley to tension the belt, playing around with pulley sizes, I ended up not needing it. The result was 25 teeth on the z-motor and 20 teeth on the c-beam side. This seems to have given me the extra 2mm to end up with exact 10mm travel per rotation of the z-motor. The full travel is accurate to the 10th of a mm measured with a caliper and the speed matches the g-code close enough. Could not be happier. Time to build a sled for this thing.

My Christmas crib this year :slight_smile:


Thanks for posting this. I asked a question in the z-axis consolidation thread, but I think this answers it. Looks like we have similar set ups, though I went with the 200mm axis, and I kept the motor up top. I am hoping to mount it to my steel sled this weekend, though that will require me to thread two more holes in the axis and put four new holes in the sled, so we’ll see how much I can get to.

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As for tonight i’m hoping to do the ‘sled balancing act’ tomorrow and add some weight plus getting a look and feel with first moves. Maslow sled the 3rd (low CGZ):

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You’ve cut things with a previous incarnation, correct? Or am I misremembering? I have yet to make chips with mine :frowning: Hoping to soon, though.

Not really. From the 21 months the first part was calibrating several times with each new release and finding bugs. The frame was modified 2 times and will have to be adjusted to this sled again. For the stuff i want to build the precision was never good enough till now, but i have big hopes with things moving on the math side and alternative calibration methods will bing me in the range to finally start cutting.
My dream is to utilise almost all of the sheet and space parts the width of a bit.
2 year old ‘lift-desk-light’ is still on hold, but hopefully this year will allow me a gradual transition from sitting at a desk to standing at it.

Nice. and I understand about the wait. I should send a pic of the shelves and desk I made from a single 4x8 sheet of MDF. Ideally I’d like to be able to make the same using the maslow, but out of plywood. I love my desk, and the shelves, which the kids have inherited (I originally designed them so I could also use them as steps to get to high shelves, so there is no danger when the kids climb that they might tip).

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can you please walk through how this was calculated? What does $18=20 do exactly? How did you arrive at that number using your 8mm c beam lead screw with 20 to 25 tooth belt driven pullies? I am using 2mm lead screw with two 12 teeth pullies for a 1:1 drive ratio with a 120rpm motor speed. How would I calculate the number to put into GC 1.25 settings or a macro.

Once I do have that number do I just hit macro 1 button before I start a cutting job?

This information was provided by @blurfl linked in my first post and came with a warning that it could affect coordinated x/y/z moves. I don’t see why because it just sets the voltage for the z-motor to maximum. The coordination should not be affected as this is calculated from the encoder steps, I guess.
Since there is neither an option in the settings, nor in the GC.ini, the 2 options are to create a macro or to change it in the firmware Settings.cpp with each new release before uploading to the arduino.
I have done no tests on coordinated moves till date!
Need to go to work, but will try to answer the rest as far as possible this evening.