Forum Replies Created
Hi Steveoz & TimF,
Good to see your progress steveoz and the design changes you made to use 25mm & 16mm pipes from Bunnings. I also live in Oz and last year I built a ‘repstrap’ version of Morgan and used the same pipes for the arms as well. I used no printed parts except for the extruder. Printing accuracy is not perfect but good enough to make my first set of real parts. (I posted details in this forum, but the November postings seem to have been lost).
I used 32mm OD PVC for the supports which I did find in Bunnings. The trick is to go to the electrical department rather than plumbing – as 32mm class-A conduit. Class-A conduit only comes in orange. There is also a grey class-B version but that has thinner walls and is not as rigid. Conduit is considerably cheaper than similar plumbing pipes. You obviously don’t need this now for your build, but other Oz builders like TimF may find this info useful.
m114 values after home then move to x100, y100.
SCARA Theta:117.22 Psi+Theta:242.69
SCARA Cal – Theta:117.22 Psi+Theta (90):35.47
SCARA step Cal – Theta:268.98 Psi+Theta:296.67
>>>g0 x100 y100
SENDING:G0 X100 Y100
SCARA Theta:33.82 Psi+Theta:144.72
SCARA Cal – Theta:33.82 Psi+Theta (90):20.90
SCARA step Cal – Theta:77.61 Psi+Theta:262.22
Machine has been calibrated to Quentin’s flowchart plus some minor tweaks to the m365 x & y scaling factors to produce a round 154 mm drive wheel. X and Y motors are 0.9 degree per step but I only have drivers capable of 16 micro-steps rather than 32. Arms lengths recorded in Marlin configuration.h are both 149.000 mm. My machine is a repstrap version with aluminium tubing arms and wooden drive wheels – but is otherwise fairly standard.
Hi Francois & Quentin,
I initially had a similar problem with the arms wanting to go behind the top platform – until I realized that one or both of my theta and psi motor connections were probably wrong. Once I got those right the calibration process went smoothly as per Quentin’s flowchart.
In case you are using Ramps electronics and standard motor wiring colors of blue, red, green, black – I got the correct results when both the theta and psi motor plugs were oriented with the blue wires facing the power-connection end of the Ramps board.
Yes by all means – use the info in any way you like – especially since it is just a variant of your brilliant design.
Here are some pics of my “Repstrap” version of Morgan…
“Strap” uses 25mm and 16mm aluminium tubing for the drive column and for the arms. The z axis drive uses plain 8mm threaded rod instead of Alpen SDS drill (unavailable locally) for the z axis. Today I ironed out a z-wobble problem by adding a bracket just above the drive wheels. This holds a flanged bearing to take the platform load and allow use of a flexible motor coupling at the top. Electronics is Ramps 1.4.
I tried to upload some pictures but failed – sorry.