D-Bot 3D Printer

[tekkydave]

Today I have managed to set up the Piezo probe correctly and can home all the axes (G28). I've also set up the mesh levelling (G29) and then tuned the bed & extruder heater parameters. I tried a quick 20mm test cube and it printed perfectly.

I love the Duet Web Control interface - it's more slick than Octoprint and can also display your mesh compensation as a graphic.

You can also edit the Reprap Firmware (RRF) config directly without having to re-upload your Arduino code. I'm still learning about RRF but it's all good so far.

 

The weird slope on this one is due to the fact that my bed is on 2 leadscrews so rocks slightly when moved up/down. Once I get the extra screw installed it should improve greatly. I have ordered some better motors - 55Nm as opposed to the 36Nm ones I harvested from the Prusa.

Next project is the 3 leadscrew mods.

 

Edited December 30, 2017 by tekkydave

[Dave_D]

told you you'd like it

[Gina]

That looks very interesting Dave   Looks like I'll have to get the Duet

I would like to get back to 3D printers but I really want to get my ASC working first.

Edited December 30, 2017 by Gina

[Gina]

My Pilot printer is playing up again (Titan is fine ATM).  The ASC/weather station is on hold awaiting parts so I'm looking at 3D printers again.  I've put my new "Mini" printer on the table to look at and think about.  This will replace my Pilot printer as a small high precision 3D printer.  The Pilot just won't hold orthogonality due to it's overall design whereas the "Mini" has a full V-groove extrusion framework and very solid.  It also uses Core-XY, moving the extruder in the XY directions rather than the Y axis by moving the print bed.  This makes for faster printing plus a much smaller footprint for the 200mm square print area.

Been looking at the Duet Wi-Fi again but not so keen on the price.  Is it cheaper anywhere else?  Mind you, for what it does it's pretty good value - combining RPi, Arduino Mega, RAMPS, stepper drivers - and it does it very much better it would seem

Edited January 2, 2018 by Gina

[tekkydave]

The only place you can but it from in the UK is direct from Duet3D, unless anyone else knows otherwise so no options on price.

It's light years ahead of RAMPS so well worth the price. The steppers are virtually silent now due to the 256x microsteps. The recommended mode is 16x interpolated to 256x.

Mind you it makes you very very careful when connecting things up  - I'm a bit OCD about checking connectors due to my BBC background but even I'm checking more than usual.

[Gina]

Hmm...  Judging by the number of Raspberry Pies I've blown up I think this might be best left.  I'm rather OCD about checking connections too but I still managed to fry the Pies!!    Or judging by the smoke - almost burnt to a cinder!!!

I take it the Duet firmware allows Core-XY?

Edited January 2, 2018 by Gina

[tekkydave]

Yep. My D-Bot is CoreXY. Have a look at The Duet Wiki for all the options. Everything is configured via g-code so no more Marlin Configuration.h and uploading the firmware for minor changes. Most things can be configured on-the-fly and you can define your own g-code macro routines in macro files.

[Gina]

Sounds brilliant   I'll probably get one once I get my confidence back after the devastating pile of dead Pies   I have learnt a few things about the RPi in the process so not a total loss

[Gina]

Made a decision - positive attitude is one on my New Year Resolutions   Ordered the Duet Wi-Fi and registered my account   Decided that a processor and interface board specifically designed for the purpose is a much better bet than a number of bits cobbled together.  Reducing connections improves reliability too.  I can't see anything against it other than "having all your eggs in one basket".  I shall just have to be super careful

[tekkydave]

Resistance is futile...  

[Gina]

I have resisted buying Borg telescopes

[Gina]

I'm a Borg beating wild witch of the west

[Gina]

Are you still using a camera with your new printer setup, Dave?

[tekkydave]

Yes, but via my RPi3 running octoprint as a temporary measure. The Duet doesn't have built-in webcam connectivity but will connect via an ip-webcam or similar. There are instructions on the Duet Wiki on setting up a normal (usb) webcam as an ip-cam using an Rpi zero (or an Rpi2,3 etc).

[tekkydave]

Screenshot from my Samsung tablet of the Duet Web Control with the image from Octoprint (running on a RPi3) embedded.

[Gina]

Ah yes, I see   I've been looking into adding cameras to my printers and trying to decide where to put them.  Looks like yours is on the RHS near the top.  I was thinking of a similar position.

I've been reading about the Duet and like the improved fan control.  I also like the idea of the web interface.  I've almost read all the Duet information and it seems to have everything covered including mains powered print bed heaters as I shall have in my Giant printer.  Certainly, the wiring up etc. seems well thought out and very logical   I also like the extra g-code controls.  I think it might let me print filament types that have proved difficult with my present printers.  It seems very likely that I shall be using the Duet for my Giant printer (when I get back to it).

Edited January 2, 2018 by Gina

[Gina]

Thought I'd have a quick look at where I'd go to with the Giant printer.  X and Y drives are sorted out but there are some decisions to be taken on the Z drive (print bed).  I was going to use two rails but I think I'll do the same as with the Mini - use the corner uprights with wheels on those.  Pull-up could be the same as the Mini too with a bar at the back and pulleys at the front with all four cords winding up on the bar (or with drums to increase diameter). 

The print bed is a bit of a problem.  I have a 400mm square mains driven heater pad, adhesive on one side to be stuck to an aluminium plate.  The latter is the problem.  I thought I had a 4mm thick piece but both 400mm squares I have are 2mm.  6mm seems to be advised.  A thought is 500mm square by 5mm thick from Amazon @ £26.57 (otherwise it seems like at least £60 for 400mm square x 6mm thick).  Wonder if this would suffice.  I know the heat would drop off near the edge of the heater but I could insulate the 50mm frame round the edge.  Might bow a bit with the heat but this may be covered by the auto-bed-levelling.  Any thoughts?

Edited January 2, 2018 by Gina

[tekkydave]

I would think for a bed that size 6mm thick would be best. Its going to be mighty heavy though. Have you considered using leadscrews to drive the z axis? I'm in the process of upgrading my DBot to triple screws driven by a single motor. The v-slot with wheels at 4 corners keeps the heavy bed (300x300x6mm) constrained well in the x-y plane but 3 screws are needed to keep it going up/down without tilting or twisting. At the moment I have 2 screws on L & R of the bed. As it changes direction either the front of the bed or back starts moving first. Probably due to the difficulty of having 2 screws at exactly the c.o.g. of the z carriage/bed combination. Three screws in a triangle arrangement will be a better system.

[Gina]

Yes, I have considered leadscrews but the friction concerned me, particularly with a heavy weight.  Actually, I've been thinking about the extreme weight and thinking it's not really practical to move this much weight.  I'm thinking instead of moving the extruder in all three directions.  Either that or abandoning the Giant printer yet again.  My Titan is working well and pretty much does all I want ATM.  I think the Giant is more for the challenge though I did think of using it to print a mini dome observatory but I've already printed most of one big enough for a single camera plus lens rig with DIY fork mount. 

[tekkydave]

Hmm. I see plenty of DBots in the 400 and 500 mm3 area using triple leadscrews and none using cord/drum for z movement. I'm not a mechanical expert by any means but I would guess leadscrews would give better accuracy which is the most important consideration. Speed and power needed/friction would be secondary. I suppose it depends whether you want a fast or accurate printer.

<stands up, ready to be corrected>

[Gina]

To date I have only seen one 3D printer using cords and drums and it was a small one with 200mm square bed.  But what I will say in defense of this system is that my Titan printer works very well - both fast and accurate   That was after I beefed up the cantilever Z axis system But the bed is not very heavy, being a silicone heater pad attached to 3mm borosilicate glass, framed with printed PETG and insulated on the underside with 12mm thick polyurethane foam and 6mm plywood.  Although a 400mm square x 3mm borosilicate glass plate is available I doubt it would be satisfactory with a same size silicone heater.

[Stub Mandrel]

47 minutes ago, Gina said:

Yes, I have considered leadscrews but the friction concerned me, particularly with a heavy weight.  Actually, I've been thinking about the extreme weight and thinking it's not really practical to move this much weight.  I'm thinking instead of moving the extruder in all three directions.  Either that or abandoning the Giant printer yet again.  My Titan is working well and pretty much does all I want ATM.  I think the Giant is more for the challenge though I did think of using it to print a mini dome observatory but I've already printed most of one big enough for a single camera plus lens rig with DIY fork mount. 

Don't forget the weight of a large print. It could be sufficient to upset the dynamics. IMHO moving the print head gives you a more predictable solution for abig printer.

[Dr_Ju_ju]

There is now a development for a large (room sized) printer, using standard Ramps\Arduino etc. have a looka @ https://toms3d.org/2017/12/11/building-a-hangprinter/

[Gina]

WOW!!!  That is da biz!!  SO, another giant printer using fishing line cord   I like it.  But it needs a whole room to work in - that is a little difficult!   Maybe a "miniature" version.  Hmmm...  Interesting   I wonder

[Dr_Ju_ju]

I was thinking along the lines of some form of frame, maybe timber, which could be assembled when required, and then packed away.