Topics created by mrehorstdmd

@chrishamm Thanks! Updated. I'll let it run for a while and see how it goes. I do run a VPN on the computer that is accessing the Duet board. I'll try switching that off and see if it behaves differently.

For anybody who does make a sand table, there is a dedicated online gcode generator for them here:

https://sandify.org/

Unfortunately it does not have a 'cat' mode..

@mrehorstdmd said in New use for Arrakis 2.0 corexy sand table mechanism:

I want to try using cement

Mix it with pigment-powder and make coloured tiles.

I went through 3 cards before I found one that was working right. That fixed it. Thanks!

@paulg4h You don't really need regulated supplies to power motors. If you use analog power supplies with plenty of capacitance you probably don't need to worry about power supplies blowing up due to transients.

The protection circuit protects anything that you might have sharing a power connection with the motor. If you don't share connections there's not much need for the protection circuit as far as I can tell.

@mrehorstdmd you can send 16 microsteps in I1 mode or up to 256 with I0 (no interpolation) mode. (Maestro is an exception, it can use I1 with other microsteps also).

But the limiting factor is the number of steps per time: the limit is about 100 to 200 kHz per axis*) from the Duet side, and typically 100...200 kHz for the external stepper driver.
E. g. 256 microsteps * 200 stepper-steps * 5 rotations/s = 256 kHz, which is already too much.

*) https://forum.duet3d.com/topic/18694/duet-maximum-achievable-step-rates

@stephen6309 Doh! Of course! Thanks!

Without knowing what sort of voltage spike to expect I'd say the safest thing to do is power those servos from a supply that is separate from the one that powers the controller board. You might not need to protect the power supply if you use an old-school, unregulated linear supply with plenty of capacitance.

The servo driver you use with the 1XD board might have some protection built in- I'd check the documentation. I used the cheapest servos available and their integrated drivers seem to be able to withstand the spikes (maybe they just used high voltage rated components), but the spikes definitely get outside the motor, requiring some protection circuit.

The REDump circuit might not be able to handle voltage spikes coming from a 48V motor as is. I'd probably use higher voltage rated Darlington transistor, diode, and capacitor. You might want to check the diode current rating against the motor peak current rating, too.

Video here

@oliof I see. Thanks!

@oliof said in Dumb question about travel limits:

you fell into a 6dof robot shaped hole (-;

yes, it's a very deep and dark hole and I haven't found my way out of it yet 😉

When the patent of Tripteron is expired, I may try to build a printer. It should have high precision. When the patent is expired, we could finish the code and push it to the official RRF together.

@mrehorstdmd
Get well soon!
I'd simply add the macro call to config-override. And put M501 in config.g as usual.

@mrehorstdmd

Very neat.

Frederick

@mrehorstdmd said in Finally... Arrakis!:

@phaedrux Go ahead, say it, it's very shagadelic!

I like the mirrors idea. I may try that...

Yeah, it would fit in a Shisha-bar, especially with psychedelic mirrors inside. (Kaleidoscope pattern)

@mrehorstdmd why not look at neopixel support now its been added for the duet 2? I think the limit is something like 60 or 80. Would this be enough?

Yes. The display is often truncated and/or rounded, but the underlying math uses single precision floats, which guarantee, in most cases, 6 or 7 significant digits of floating point. This means that the translation from base-10, to binary, and back to base-10 does not change the value of those 6 digits. Beyond that, there will be small errors.

In practice, this means that if you are specifying 5.0025 as a value, you still have an extra digit. If you specify 100.0025, that last 5 is not guaranteed to translate to binary and back cleanly (though, in some cases you are guaranteed 7 digits), it might turn out as 100.00250244140625 or something. That said, since it would be close enough, the step generator would likely round it to the intended value and there may be no problem whatsoever.

This nifty calculator helps illustrate what happens: https://www.h-schmidt.net/FloatConverter/IEEE754.html

I guess you're not always guaranteed to have 6 digits, as in the case of 1.02, but it's close enough and you're guaranteed to NOT have precision past 7 digits.

@dc42 Thanks, that's the thing I want to test, so I will interrupt the 24V supply instead of using M17/M18.

@zapta The supply I used had overvoltage protection. good for 28.8-33.6 V. Apparently the voltage spike exceeded 33.6...

It's actually PT100 connected to the duet3d daughterboard.

OK, got it working.

Thanks!