I'm tuning in my Eustathios Spider 2 and the Z is complicated because there

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(Ted Huntington) #1

I’m tuning in my Eustathios Spider 2 and the Z is complicated because there are 2 different gears 32T on the screw pulley and 20T on the motor pulley. The ball screw is 1204, so 4mm pitch (I see Eric uses a 2mm pitch lead screw). Looking at Eric’s config file my values are somehow double in Marlin. He has 160,160,2560 but mine are closer to half that: 80,80,(1280?) - on a 3D benchy test print I find that 1280 is about 1.2x too small. I reached 1280 by:
200steps * 16microstep / 4mm pitch = 800 * 32/20= 1280 steps/mm
but 1.2x = 1536steps/mm
does anybody know the formula there?

(Walter Hsiao) #2

The calculations seem fine to me, are you sure you received a 20 tooth pulley and not a 16 tooth version? If you’re using a 16 tooth pulley (or a 40 tooth pulley on the ballscrew, but I don’t think that would fit), it should be 1600 steps per mm on z.

(Ted Huntington) #3

@Nathan_Walkner
I got these: http://www.robotdigg.com/product/29 1.8degrees so definitely 200 steps (with 16 microsteps set on my ramps 1.4 board). I am realizing now that perhaps Eric is using 0.9 degree (400 steps) motors- but all Robotdigg has in 60mm size is that one I bought, which is 1.8degrees.

(Ted Huntington) #4

@Walter_Hsiao
I’m fairly sure they are 20 tooth pulleys- how are you calculating 1600 steps/mm on the z? I calculated 1280, but in practice I have tuned it to around 1462-1494 steps/mm on the z.

(Walter Hsiao) #5

1600 is only if you’re using a 16 tooth pulley, same as your math above, 800 * 32/16 = 1600. I think I’m running at 3200 z-steps/mm (16/32 pulleys on z, 400 step motor, and 4mm pitch ballscrew).

(Ted Huntington) #6

@Nathan_Walkner
maybe there is someway to check on the LCD in Marlin- I just started using the LCD interface.

(Ted Huntington) #7

oh ok- so the equation I am using is correct. I have no idea, but for whatever reason 1494 seems to be pretty accurate. Thanks everyone for your help.

(Ishaan Gov) #8

I don’t know if @Eclsnowman runs ball screws or TR12x2 Misumi Leadscrews; if it’s the latter, that may explain why his numbers are about double yours

(Ted Huntington) #9

@Ishaan_Gov
Thanks Ishaan- the last time I saw Eric still had lead screws on his Eust Spid 2 but wanted and recommended using ballscrew which I did. That explains why the Z is double but what explains the x and y being double? The BOM doesn’t specify 1.8 or 0.9 degree so I’m not sure what Eric has, but the RobotDigg only sells 1.8 for 60mm size.

(Daniel F) #10

Does the system turn smooth? Maybe you are loosing steps. Did you adjust the current of the z stepper? Are the pulleys tightened properly? It could also be slip on the pulleys, as you configured more steps that it should actually be.

(Ishaan Gov) #11

@Ted_Huntington , what’s the microstep setting on your drivers?

(Ted Huntington) #12

@Daniel_F I tightened the belt and I think that helped somewhat- and I am noticing something unusual on the Z. There is a “thunk” sound in between layers (when the X and Y are moving but not the Z). I changed the step stick and still the thunk is there, regularly for every layer. The firmware (Marlin 1.1.0-RC2) is pulsing the z motor- but I have seen this when the step stick is damaged, and when the speed was set too high. I have another RAMPS board I may try- just to eliminate if it is the PCB- but I think it must be firmware.

(Ted Huntington) #13

@Ishaan_Gov
they are all set for 16 microsteps (all 4 jumpers in place on the RAMPS).

(Ted Huntington) #14

ok wow I totally solved it, whew! When I upgraded from Marlin-1.1.0-RC2 to RC3 I found what was wrong. In Marlin, never set
#define DISABLE_Z false
to true- in particular on a Eustathios, because it will temporarily unlock the Z stepper motor and the stepper motor falls back a little. I had set this to true on a different printer because sometimes it is nice to slightly adjust the Z on the first layer- but it totally caused havoc - so I will never do that again. I guess on a RepRap Mendel it doesn’t matter as much because there is maybe less weight on the Z motor?

After I set that back to false I find that 1280 works fine- thanks everybody for all your help.