MPCNC stutters

[jeffeb3]

@remon_v

But is it necessary to tram the CNC at this point?

No. The worry was that it was so far off that it was causing big bites. I don’t think you’re that far off.

@remon_v

Is the Shapeoko comparable to the MPCNC in terms of rigidness?

I don’t know anything about the shapeoko.

@remon_v

What I understand about chipload, is if you go to slow you dull your router bit.

It depends. You will need to replace your bits. They are consumables. They will make more cuts to remove the same amount of material, and they can get hotter, which can dull them faster, but only if you exceed the temperature where they get softer. It really isn’t something a beginner should worry about, IMO.

You have to see there are people who think things have to be perfect, and they end up spending $15k on a machine and follow all the rules. That’s fine. This is a different beast. This is about opening a door that was previously closed to the rest of us. If you can cnc something, then you’ve got a lot of projects that open up. You won’t be able to do it fastest or with the most precision. But you can do it.

The remaining chatter doesn’t look too bad. A finishing pass would clean that right up.

[remon_v (Ramon)]

@jeffeb3

No. The worry was that it was so far off that it was causing big bites. I don’t think you’re that far off.

Good to hear, then I will leave it like this for now, I first want to do some projects.

@jeffeb3

I don’t know anything about the shapeoko.

It’s also a hobbiest oriented machine like the X-carve. But they cost around $2000,-

@jeffeb3

It depends. You will need to replace your bits. They are consumables. They will make more cuts to remove the same amount of material, and they can get hotter, which can dull them faster, but only if you exceed the temperature where they get softer. It really isn’t something a beginner should worry about, IMO.

I’ll do some testing, what do you think about the Feeds & Speeds I used for the butterfly?

@jeffeb3

You have to see there are people who think things have to be perfect, and they end up spending $15k on a machine and follow all the rules. That’s fine. This is a different beast. This is about opening a door that was previously closed to the rest of us. If you can cnc something, then you’ve got a lot of projects that open up. You won’t be able to do it fastest or with the most precision. But you can do it.

Yes exactly, I’m also on the Dutch cnczone forum. Sometimes it’s easier because I can write in Dutch. But the machine most of the guys at that forum have are more (semi) professional.
The first advice someone gave me is that my DOC was to low… it should be at least 9mm or so…

I’m pretty happy with my machine, I still can’t believe this budget machine can do great stuff.

Yes I should have done a finishing pass, I’ll do that next time.

[remon_v (Ramon)]

Hey guys,

So someone asked me to do an engraving on some coasters so I was trying to do this on some MDF first. The result is pretty good, although it’s really small 80x80mm.
What I do notice is the circle isn’t a circle but more like an egg shape and not everything is straight (like the small letters). It’s a bit squased in the height/Y-axis, so the ratio between the x and y isn’t correct.
How can I improve this?

I did improve some things in Fusion 360 already.

[remon_v (Ramon)]

I haven’t tried anything yet, but would it be better to set my microstepping a bit lower? I think it’s set to 1/32 microstepping now. Is 1/16 better for the MPCNC?

[jeffeb3]

No. IMO, there isn’t any significant difference between 1/16 and 1/32.

This looks like a mechanical issue to me. Loose pulley, or loose belts, or a long Z or something.

[remon_v (Ramon)]

I will check everything when I’m home… could it be that the bolts are too tight? I’ve tightened everything. The X and y axis doesn’t have to be really tight right?

And what about firmware settings of my stepper motors? I saw this thread:
https://forum.v1e.com/t/skr-v1-3-tmc5160-voltage-question/11988

Is this possible for the MKS Sbase board?

I have these stepper motors, 17HS19-2004S1

[jeffeb3]

What kind of drivers do you have? Drv8825s have a little screw on the top to adjust the current.

[remon_v (Ramon)]

Yes those drivers, but they are on the board I think… they can’t be taken off or something.
Maybe a jumper?

[jeffeb3]

Ah. It probably has digipots. But I’m not familiar with that board.

[remon_v (Ramon)]

Oké, so I should be looking in the firmware somewhere?

This is what I found on a google search:
https://www.modelbouwforum.nl/media/50095652_598514860601811_7200556317201661952_n.244408/full

[remon_v (Ramon)]

Hey Jefe,

In my first thread you also mentioned digipot, I didn’t understand it at the time but I still don’t know what you meant by it. Could you have a look again please?

Makerbase MKS Sbase

Don’t mess with gcode until you have all the axis driving the right direction. There’s no reason to think playing a gcode file will fix things when a manual move is broken. Are you sure you successfully flashed it? Send an M119 and see that there are X2 and Y2 in the report. You might want to unset the digipot current, and change the driver type, but those changes would be subtle. Be sure to adjust the driver current with the little trim pot. You can, I think it is in the advanced and it …

In ‘Configuration_adv.h’ is where I find the settings of digipots, btw how do I post the code like you do in the other thread?:

/**

• @section stepper motor current

• Some boards have a means of setting the stepper motor current via firmware.

• The power on motor currents are set by:

• PWM_MOTOR_CURRENT - used by MINIRAMBO & ULTIMAIN_2

•                     known compatible chips: A4982
  

• DIGIPOT_MOTOR_CURRENT - used by BQ_ZUM_MEGA_3D, RAMBO & SCOOVO_X9H

•                     known compatible chips: AD5206
  

• DAC_MOTOR_CURRENT_DEFAULT - used by PRINTRBOARD_REVF & RIGIDBOARD_V2

•                     known compatible chips: MCP4728
  

• DIGIPOT_I2C_MOTOR_CURRENTS - used by 5DPRINT, AZTEEG_X3_PRO, AZTEEG_X5_MINI_WIFI, MIGHTYBOARD_REVE

•                     known compatible chips: MCP4451, MCP4018
  

• Motor currents can also be set by M907 - M910 and by the LCD.

• M907 - applies to all.

• M908 - BQ_ZUM_MEGA_3D, RAMBO, PRINTRBOARD_REVF, RIGIDBOARD_V2 & SCOOVO_X9H

• M909, M910 & LCD - only PRINTRBOARD_REVF & RIGIDBOARD_V2

*/

//#define PWM_MOTOR_CURRENT { 1300, 1300, 1250 } // Values in milliamps

#define DIGIPOT_MOTOR_CURRENT { 138,138,138,138,138 } // Values 0-255 (RAMBO 135 = ~0.75A, 185 = ~1A)

//#define DAC_MOTOR_CURRENT_DEFAULT { 70, 80, 90, 80 } // Default drive percent - X, Y, Z, E axis

// Use an I2C based DIGIPOT (e.g., Azteeg X3 Pro)

//#define DIGIPOT_I2C

#if ENABLED(DIGIPOT_I2C) && !defined(DIGIPOT_I2C_ADDRESS_A)

/**

• Common slave addresses:

•                    A   (A shifted)   B   (B shifted)  IC
  

• Smoothie 0x2C (0x58) 0x2D (0x5A) MCP4451

• AZTEEG_X3_PRO 0x2C (0x58) 0x2E (0x5C) MCP4451

• AZTEEG_X5_MINI 0x2C (0x58) 0x2E (0x5C) MCP4451

• AZTEEG_X5_MINI_WIFI 0x58 0x5C MCP4451

• MIGHTYBOARD_REVE 0x2F (0x5E) MCP4018

*/

#define DIGIPOT_I2C_ADDRESS_A 0x2C // unshifted slave address for first DIGIPOT

#define DIGIPOT_I2C_ADDRESS_B 0x2D // unshifted slave address for second DIGIPOT

#endif

//#define DIGIPOT_MCP4018 // Requires library from GitHub - stawel/SlowSoftI2CMaster

#define DIGIPOT_I2C_NUM_CHANNELS 8 // 5DPRINT: 4 AZTEEG_X3_PRO: 8 MKS SBASE: 5

// Actual motor currents in Amps. The number of entries must match DIGIPOT_I2C_NUM_CHANNELS.

// These correspond to the physical drivers, so be mindful if the order is changed.

#define DIGIPOT_I2C_MOTOR_CURRENTS { 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 } // AZTEEG_X3_PRO

[remon_v (Ramon)]

This is what I fine on this website:
https://git.x2d2.de/3D-Printing/Marlin-Firmware/blob/1dad6e754b1fc09e9018e663c7afc5da1794d0ae/config/examples/Mks/Sbase/Configuration_adv.h

So I think I have to alter this line:
#define DIGIPOT_I2C_MOTOR_CURRENTS { 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 } // AZTEEG_X3_PRO

to something like:
#define DIGIPOT_I2C_MOTOR_CURRENTS { X.X, X.X, X.X, X.X, X.X } // MKS SBASE: 5

Fill in the Current of my stepper motors in the ‘X.X’

[ttraband (Tom Traband)]

Older drivers line the A4988 and the DRV8825 have small potentiometers (pots) on the board for manually adjusting the maximum current to the motors. Newer drivers allow this to be set digitally through firmware/software, so they are digi-pots.

[remon_v (Ramon)]

Thanks Tom,

So should I alter the line in the ‘Configuration_adv.h?’
And my stepper current is 2.0A, so should I change it to 2 Amps?

[ttraband (Tom Traband)]

I’m running the older drivers, so I can’t advise you on what settings to use. I do recall reading you had to pick a value that mapped to the current you were aiming for, it wasn’t as simple as entering the amps you wanted, but since it wasn’t directly applicable to my situation it hasn’t stayed in my head.

[remon_v (Ramon)]

I will wait untill someone verified it before I change something

[jeffeb3]

Like I said, I haven’t used that board, so I’m not sure which of the current settings is the right one.

But it is probably one of those you mentioned.

Digipots are potentiometers that are set digitally. Which means the software can control the current limit. There are many different types, controlled with different software. So you’ll need to figure out which software setting is right for your board.

[remon_v (Ramon)]

What current shall I try? It’s rated for 2.0A… if I feed it with 1.6A (80%) would that be a good value?

[jeffeb3]

If you go too high, the motors will heat uo enough to deforn the pla. You want to keep them under about 50C. 1A seems like it should be fine, honestly.

[remon_v (Ramon)]

Oké… I feel really stupid… I think I know why my latest test/work was out of ratio (squased).
1 of the stepper motors wasn’t connected and it wasn’t really obvious at all.

Now the next problem… now I want to get the dual endstops to work.
When I home the Y-axis everything is fine, but when I home the X-axis something is not working.
1 of the stepper motors isn’t moving at all.