Frage Scale Issue

First post here, but have been reading on here for about 3 weeks.

Just got a 420 unit and am running VCarve and am having trouble with scale. The drawing I did is 6in x 6in, but during an aircut trail run, the machine moves maybe 1/2 an inch in any direction. The preview in UCCNC looks like the drawing, so i'm guessing a scale issue.

Toolpath was exported out of Vcarve with Mach2/3 Inch settings.

Hi,

You've guessed correctly - it's an Imperial to metric issue!!

As far as I know UCCNC only "knows" about metric, so you will have to multiply eveything by 25.4!! All the parameters in the SC420 are metric (mm) too, so you have little choice anyway.

In VCarve, check the "mm" box and adjust all the sizes you have accordingly. Your .txt file says it all, the machine was moving 6mm rather than 6".

I find helps to remember that 1mm = 40 thou (very nearly) and 1 thou = 25 microns.

Peter

The UCCNC is calibrated for "steps per unit".

The STEPCRAFT parameters are setup in steps/mm

So the machine is tuned such that the calibration to the motor drives is calibrated against mm's of movement.

one could calibrate to inches also - and then the inches in Vcarve would work.

Rory,

I stand corrected - sorry if I gave the wrong info, at least I know now!!

Thanks for the help guys.

So let me see if I understand completely- I need to completely re-draft my work in metric, or teach UCCNC the proper conversion steps, correct?

Hey Stepcraft USA- If you are reading this thread, remember when we talked about how the price in the US is higher than the equivalent price in Europe and you said part of the extra funds was to provide specific support to US customers?

Here is an opportunity....

Hi,

Remotruker schrieb: ... remember when we talked about how the price in the US is higher than the equivalent price in Europe and you said part of the extra funds was to provide specific support to US customers?

Here is an opportunity....

Good luck with that! I can't recall any customer support from the US Stepcraft division in this forum. And yes - I was also in the market for a little Stepcraft (2/300) machine but then I've seen the asking prices on the US Website and immediately they lost me as a US customer ...

Think about it:
Germany: SC 2/300 for 799 € incl. TAX ($862.00)
US: SC 2/300 for $1499.00 plus TAX (= approx. $1630.00)

Considering shipping cost, customs fees and a working German forum - I assume it would be a better deal for me to order in Germany ...

Remotruker schrieb: Thanks for the help guys.
So let me see if I understand completely- I need to completely re-draft my work in metric, or teach UCCNC the proper conversion steps, correct?

No, you do not need to do anything to your drawing. You can use either metric or those old funny units from past when you make drawings. What you need to do is to select correct post processor when you are saving the g-code. The correct postprocessor for stepcraft machine configured to use UCCNC in metric is "Mach2/3 Arcs (mm) (*.txt)". So you need to ALWAYS select that post processor regardless whether you work on mm or inches in your CAM software.

When you select correct post processor, then the post processor takes your units (mm or inches) used in the CAD/CAM software, and convert them to correct units for the CNC machine (mm in stepcrafts case).

So simply save the g-code again in the V-Carve and select correct post processor and then it should get correct scale in UCCNC.

The g-code itself do not really have units in it, it is just telling that move to coordinates X100 Y200 Z10. The UCCNC then will know that to move one unit of g-code it needs to send certain amount of steps to the stepper motors, and for Stepcraft 2 machine that configured to be 133 steps for one unit in g-code.

On the other hand 133 steps in that machine will move tool for one millimeter. So when you use the (mm) version of the g-code the CAM software knows that one g-code unit matches one mm, which is what the UCCNC is configured to do also, so scale is correct.

BTW, you can also change the units in V-carve at any time, and that should not affect the drawing at all, i.e. simply select the "Set job dimensions and origin" button from the File operations list (2nd row, first icon) and change from mm to inches, and it will automatically convert everything for you. I.e. if you had 30mm circle before after that you have 1.1811 inch circle now.

i have recently set up my 6040 ,and have completed samples , now my uccnc has told me that after completing some measurements on all axis ,that i need to readjust the scale so from 1.0000 to 0.80000 now when i try to begin , there is a arc difference on xy , so it does not begin