Lowrider seems to be cutting way smaller than I designed. please help

Software / Firmware Fusion360
1

I designed a piece in fusion it’s a 16" by 16" piece but for some reason it moves like it’s trying to fit the shape inside a penny, this also happened with the crown design I got from the V1 site. I even connected a pen to my cnc and it makes the right pattern just much smaller than what I want.

2

The units in the gcode have to be mm. If inches made it all the way to the gcode, then it will print 25.4x too small…

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3

I had the same problem, and I needed to change what kind of stepper drivers I had in Marlin code, also I had to adjust DEFAULT_AXIS_STEPS_PER_UNIT.

Don’t be intimidated by it. :smiley: You can also search V1 forum about it.

4

You should not need to adjust that with the common boards we use here or you configured the firmware yourself.

5

Okey. And I am using V1 Marlin.

Hardware
Bolt+Belt+Motor Kit from Ryan
Ramps 1.4 + LCD from Ebay

Firmware
Marlin-MPCNC_Ramps_T8_16T_LCD_32step

I had to adjust this (default was DRV8825):

#define X_DRIVER_TYPE  A4988
#define Y_DRIVER_TYPE  A4988
#define Z_DRIVER_TYPE  A4988

And this (default was 100, 100, 400, xxx – I think) :

#define DEFAULT_AXIS_STEPS_PER_UNIT   { 100.3, 100.3, 400, 100 }

Did I choose incorrect Marlin version?

6

AFAIK the A4988 drivers are max 16 step/unit, so, the 16" becomes 16 mm and steps/unit are wrong can indeed lead into penny-wise :wink: formatted cut’s…

1 Like
7

Aha, okey. That makes sense.

But I can only find 32step pre-configured for Ramps 1.4:

8

You could try dividing the steps per unit for the X and Y axis by 2…

9

@Zager360, ignore this side conversation. Considering the scale of the error on your post, I suspect it is units in the gcode.

@dailybombs, Yes, the Ramps firmware is configured for drv8825s, which (when all the jumpers are installed) are 1/32nd stepping, which is 200,200,800. The a4498 maxes out at 1/16th, which is 100,100,400. If you want it at 100.3,100.3, that’s not a big deal. You didn’t have to change the driver type, but it works a little better that you did.

BTW, we have newer firmware. We haven’t updated that github, but the new firmware is in MarlinBuilder releases. There is a V1CNC_Ramps which is the same as the one you are using, but based off of newer Marlin firmware. We’ll be updating the MarlinBuilder ones in the future and no longer updating the one you downloaded.

I’m pretty sure that this isn’t OP’s problem, just because of the size of the scale.

10

The problem was within the .gcode, I change my units from inches back to millimeters and that fixed it.
Thanks for all your help!

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