D-Bot 3D Printer

[tekkydave]

10 hours ago, Gina said:

Which slicer do you use with the Duet Dave?

I use Slic3r these days. I liked Cura but had problems getting it to run consistently on Ubuntu. 

[tekkydave]

10 hours ago, Stub Mandrel said:

I do wonder if without the ldlers the back one would be prone to slipping.

I didn't have any slippage when I first installed them but I wasnt happy that the belt only contacted about a third of the pulley. My main issue is the motor stalling, probably too much friction from the weight of the bed and the screws. 

[Gina]

Sounds like you need a bigger motor.  What size are you using at present?  (length)

Edited January 22, 2018 by Gina

[tekkydave]

1704HS168A - Nema 17 77ozin (=55 Ncm) 1.68A current. Got it from Ooznest

http://ooznest.co.uk/3D-Printer-Electronic-Parts/Motors/NEMA-17-Stepper-Motor

Its 48mm long.

Edited January 22, 2018 by tekkydave

[tekkydave]

I have to add that it is all working fine at 180mm/min which is as fast as it needs to be. Accuracy is more important than speed.

With dual leadscrews each with their own motors I could only get 225mm/min.

Edited January 22, 2018 by tekkydave

[Gina]

There's a 60mm long NEMA 17 though not from Ooznest.  I've seen them from other sellers I use.  But if you're satisfied with what you've got, fair enough.

[tekkydave]

Another option is 3x leadscrews each with their own motors. This would allow true bed levelling by the Duet but would also need either an expansion board (Duex) or custom driver board.

[tekkydave]

4 minutes ago, Gina said:

There's a 60mm long NEMA 17 though not from Ooznest.  I've seen them from other sellers I use.  But if you're satisfied with what you've got, fair enough.

Ooznest do a 60mm motor with 82 Ncm holding torque. Would probably give some improvement but its not going to be blindingly fast in any case.

[Dr_Ju_ju]

Duet, by default wires the two Z motor ports in series on the board, so in theory you could just do some additional breakout wiring to have all three motors running in series As long as the drivers can supply enough current (2.4A limited from 2.8A) (https://www.duet3d.com/wiki/Duet_Features)

Edited January 22, 2018 by Dr_Ju_ju

[tekkydave]

Yes, that's a possibility.

I'll see how it goes for now before spending any more cash on it.

[tekkydave]

I might try running it off 24V to see if it makes a difference. I'll disconnect the 12v fans & extruder heater cartridge first though  

[Gina]

I was going to suggest running 3 motors in series from a 24v supply.  No individual control though.

[tekkydave]

Just did a quick experiment running the Duet off a 24V supply.

With 12V I was getting 180mm/min maximum z axis speed

With 24V I can get it up to 380mm/min before the motor starts stalling

24V might give my 0.9 degree Titan motor a bit more oomph as well.

Seems a no-brainer to go 24V then. I'll have to get a 24V PSU, 24V fans and a 24V heater cartridge.

I can't think of any downsides to it unless anyone else has a view.

[Dr_Ju_ju]

As you are driving the bed from the mains, as am I, I bought one of these https://www.ebay.co.uk/itm/24V-Best-quality-15A-360W-Switching-Power-Supply-For-LED-CCTV-Regulator-AC-to-DC/252989158017?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649, the only problem with it, was a noisy fan, soon rectified with a quieter device.

Also double check all the end stops, any case fans, LED strips etc. and plan accordingly...

[tekkydave]

Thanks for the link. I was hoping to get a slightly less powerful PSU and get one without a fan if possible.

As you say I don't need Amps for the bed as it is on a SSR. I could probably manage fine on a 240W (10A) supply.

[Dr_Ju_ju]

Non fanned supplies have more 'open' casing, giving the potential for small items, like motor screws, to drop inside... 

I worked on the basis of 5 off 2A motors plus additional for heaters fans etc. giving the closest approximation to 15A

[tekkydave]

Unless I change the design I only have 3 large motors and 1 small one (extruder). I suppose a larger PSU gives a bit more room for expansion later with LED lights etc a possibility.

[Gina]

I plan to use 24v for my Giant printer.  I already have a 24v 60w cartridge hotend heater to go with a Volcano hotend.  I shall need a 24v hotend fan.  I might also change to 24v on my Titan printer (I have two 24v hotend heaters).  It has a 24v bed heater running off one of those 24v 360W PSU that Julian linked to.  That has a DIY power MOSFET driver but the Duet could handle the 15A directly, though only with a massive 24v PSU.  It would be nice to upgrade the bed heater on that to mains voltage - makes sense.

[Gina]

The 24v PSU fan doesn't make much noise depending on the load and even at full load it's not too bad.

[Gina]

One thing I'm thinking about is that if I want to run off 24v, I can't use an ATX PSU (12v).   I shall want a 5v PSU and an SSR to switch the main 24v supply so that the printer can power down (except for 5v) when printing has finished and hotend cooled.  I often print overnight.

[tekkydave]

The 12V supply I have at the moment had a really noisy fan in it. Replaced it with a quieter one but it was still fairly noisy. I ended up putting a buck converter inline with the fan to slow it down a bit!

[tekkydave]

Ok. I have taken Julian's recommendation on the PSU and ordered one. Also ordered the 30mm and 40mm fans I need plus a 60W 24V cartridge heater from Makers Hut.

[tekkydave]

16mm test cube. The height is near enough

 

[Dr_Ju_ju]

If you don't want to wade through the myriad pages of info on configuring the Duet, I've come accross this site which boils down the info into manageable chunks https://betrue3d.dk/blog-posts/ especially the "configuration walkthrough and adjust" which is a better explanation for the PID tuning...

[tekkydave]

Wow - loads of useful info there. Cheers.