Here is a pic of my new rails.
Steve,
Your table looks like a really clean build. Have you tried just shortening your X axis pipe a bit and letting them rub? I use a waxed metal rail (Superstrut)and the friction is minimal.
Also if you have TCM drivers I recommend trying sensorless homing instead of endstops and see if its accurate enough for you. I have endstops on my MPCNC and Sensorless on the LR and far prefer the sensorless now that I have them tuned.
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My latest mod is similar to Jeff’s angles but using 3/4 square wood and it is better but still some sideway movement. How about printing some hard wheels and running them in a “c” channel?
Tell me more about sensorless homing. I have TCM2208 drivers.
Sorry. I think your need the 2209 chips, that was the major upgrade from the 2208’s. The good news is if you swap them there aren’t really any config changes.
There is already a build floating around that has everything you need as far as the firmware but the line you are after is in Configuration_adv.h:
#define SENSORLESS_HOMING
I didn’t bother with setting the sensitivity in the firmware but just used M914 codes to tune it. I would guess every build is different depending on steppers, current, and build but mine are X80 Y60 Z60.
I’m not a super precision guy but on jobs that I’ve had to restart my XY repeatability is dead on. Z is less so but that’s more because of my build than the sensors.
Good luck!
Nice clean looking table, Jeff.
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Michael, as I understand it, senseless homing works by detecting resistance in the steppers. It seems to me that the Z direction would be difficult to detect. Do you home Z up or down? Down would seem to stretch the couplers with less force than needed to lift the carriage.
I home up but have one of the doodads on my coupler that I found here on the forums.
It keeps the coupler from over stretching.
Here’s the part:
From @anttix
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Oh I forgot one piece
There is a bumper on the bottom of z tube that makes contact.
I guess you could also put it on the bottom of the z screw if you wanted.
Ok… its cutting square and accurate straight cuts. 100mmx200mm is good. The holes are a progression from 22mm dia increasingly by .05mm to find right fit for 1/2"pvc pipe. The 22.0mm hole measures 21.4 in x direction and 20.8 in y direction.
All hole are similarly lopsided. Gcode is from fusion 360. Any ideas why?
edited previous post
If the holes are starting and ending in the same spot then you have flex somewhere in the system. In order of easy to hard :
Check belt tightness
Reduce length of exposed bit
Increase amount of finishing cut
Reduce depth of cut
Slow down.
Look for plate flex
Just as a test increase your finishing pass to 1mm and see what happens.
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Sorry for delay… got distracted playing with v-carve…
Anyway… back to wanting dual endstops installed and looking at Marlin_V1CNC_Skr1p3_DualLR_2209_2.0.7.2_510-src
Is this a good place to start?