Calibration Accuracy

Hi All,

I finally have my Maslow setup and running. I have run the calibration several times already, (feels like groundhog day every time) reinforced the top beam to reduce flex, fairly stiff now and introduced the weighted chain tension system.

I was running my first test cuts for a project utilising a 3mm MDF sheet (because it’s cheaper than an $80 18mm birch sheet) and I have found it is cutting outside of the work area to 10mm below bottom edge) when the actual height of the drawing (1219.2mm) should fall just inside the edge of the work area.

What am I doing wrong? Is there a way to correct this? Is it rotational radius or distance between motors?

Thanks y’all in advance.

My MakerMade Ring Maslow 12 foot setup is as follows;
Measured distance between motor shafts (centres) = 3580mm +/- 0.5
Calibrated distance between motors = 3561.32
Measured Motor Vertical Offset = 565-568mm
Calibrated Vertical Offset = 566.4
Measured work area = 2444mm x 1223mm
Triangulation System
Bottom Feed

Calibrated Rotation Radius = 133.8
Calibrated Chain Sag = 29.490565

Calibration Benchmark Test Results

Small squares Width = Perfect
Small squares Height = 1.125 Avg
Horizontal Measurements = 0.5 Avg
Vertical Measurements = 9.83333333 Avg

Calibration Benchmark Test Actual Measurements

Square top left = 100 x 101.5
Square Top right = 100 x101.5
Square bot left = 100 x 101
Square bot right = 100 x 100.5

top horizontal = 1904.5
Centre Horizontal = 1904.5
bot horizontal = 1905

Vertical Left = 910
Vertical Centre = 910.5
Vertical Right = 909

Other Details

Ground Control v1.26
Sled Diameter 16”
Sled thickness 16mm (Melamine)
Router and Ring hardware centered
Sled weight = 9.5kg (20.94lb)
Frame Angle = 15 degrees
Wasteboard 18mm MDF

Fortunately this might be one of the easiest issues to fix. The vertical offset of the motors will shift everything up without causing any distortion so you should be safe to adjust that setting without impacting any of the others.

Hi there @bar,

Thanks for your reply. I switched from ground control for Mac to WebControl Windows so I could run the Holey Calibration. Had to dust off the old Windows 8.1 laptop and install updates.

I ran Holey Cal once and got a Calibration error of 2.68, ran it a second time, and got 3.54. After which, I ran my test drawing again, and it looked good. Ran the Holey Cal a third time and the final results were;

Height = 555.13726
Distance tween Motors = 3586.80356
Left Chain Tolerance = 0.32451
Right Chain Tolerance = 0.22113
Calibration Error = 4.215etc,etc.
Ran my test cut again, and all looks really good.

So yes, you are right, lessening the vertical offset was one of the necessary changes. As well as distance between motors. It was very nice to have the calibration program work this all out for me though. Thanks to all who developed that @madgrizzle and others.

I would like to say that I am really impressed with what you have conceived and developed here. The Maslow CNC router is AWESOME! I’d like to buy you a beer @bar. :wink:

I filmed my process of modifying a Ryobi RRT1600-S, one of the cheapest routers available at our HomeDepot equivalent here in Australia. So I will post that up soon.