D-Bot 3D Printer

[tekkydave]

This topic will describe the build of my D-Bot CoreXY 3D Printer. I have already built a Prusa i3 3D Printer but have realised as I have modified and improved it that I have pushed it as far as it will go.

This new build is based around the D-Bot printer by spauda01 and will have a print volume of 300x300x375mm. I will be proceeding as funds allow as the total estimated cost is about £500.

I will be re-purposing as much as I can from the Prusa e.g. motors, electronics, hot-end. I will probably re-use the 200x200mm print bed initially until I get a 300x300mm to replace it.

I have found the funds to make a start and have ordered the D-Bot Rail Bundle from Ooznest. This will give me all the required v-slot extrusions, cut to length and ready-tapped where required.

I'll be printing the plastic parts needed on the Prusa in order to assemble the basic frame. If the quality is not 100% I can always re-print them once the D-Bot is functional.

Edited April 30, 2017 by tekkydave

[Dr_Ju_ju]

Good luck !!

My 2$ - one thing I've found with the bigger platforms is the limitations of the Ramps\Arduino controllers. I've used Smoothie Ware v2 board http://smoothieware.org/smoothieboard, yes its more expensive but gives better control. 

[tekkydave]

Yes, I was thinking about looking at better electronics at some point. Thanks for the link.

[Gina]

Very interesting Dave   I look forward to seeing your build   It's similar in many ways to my Titan printer but more heavily engineered and with more Z capacity (375mm v 330mm).  You will need a bigger fume cabinet than mine to cater for the extra height and the loop of filament feed tube.  The heavier engineering may make yours more accurate but I still have work to do on mine so can't say yet just how accurate it is.  I'm hoping to get back to mine soon.  I'm lucky in having plenty of space so will be retaining two working 3D printers - I have retired my little Up Plus 2.

[tekkydave]

The v-slot arrived today from Ooznest. All nicely cut to length, tapped where required and labelled with the D-Bot part ids.

I have started printing the plastic parts on the Prusa in PLA. I can reprint any I want to replace on the D-Bot later.

 

[Gina]

Handy to have it all cut to size and pre-tapped   But how much extra did it cost you?

[tekkydave]

The D-Bot Rail Bundle was £106 + p&p (£113.85 total). Pretty good value and no cutting to do.

They do a Motion Bundle too but I have some components already so will just buy what I need.

Edited May 11, 2017 by tekkydave

[Gina]

Ooznest do seem to be a very good company - I've had very good service from them and their aluminium extrusion is a lot cheaper than other extrusion.

[tekkydave]

The PETG filament should be arriving today so I can get on with printing the parts. I might go back to using a direct extruder for this as the bowden setup on my Prusa seems to be more trouble than its worth. At the speed I normally print 40-60mm/s the Prusa doesn't benefit much from bowden. Faster speeds cause too much shaking/vibration either way. I need a decent set of prints for the D-Bot then the Prusa will be giving up it's motors, electronics plus a few other small parts for the D-Bot.

[Gina]

That's interesting Dave, I'm finding the same with Bowden feed and going back to a direct extruder on my Titan printer.

[Chriske]

Dave,

Make that printer as sturdy/stiff as you possibly can..!!
During the past 3 years we've(3 friends - telescope and printer nerds) built about 20 different types of 3D-printers. None of them produces 100% perfect perimeters.

I now have finished a printer of own design. It's casing is a very strong wooden box and that is one of the main reasons it outperforms all previous printers we've built in the past. No more ripple on the perimeters and no more ghosting around holes. As a matter of fact, it was very strange to have these perfect perimeters after 3 years of building and testing printers.
Second reason why it performs so well is that I abandoned these LMUU linear bearings. I make my own (adjustable)bearings. So there's absolutely no play on the axis at all.

[Gina]

I shall be interested in how you get on with PETG filament.  I've looked at it's properties, particularly compared with ABS which is my current favourite filament.  The lack of fumes is certainly a plus point and means you don't need a fume enclosure.  OTOH with the amount of filament I get through cost is a factor.  Also, the ability to use acetone for solvent welding ABS is something I find very useful for making awkward or very large objects.  I'm always on the lookout for different filaments though.

[tekkydave]

6 hours ago, Chriske said:

Dave,

Make that printer as sturdy/stiff as you possibly can..!!
During the past 3 years we've(3 friends - telescope and printer nerds) built about 20 different types of 3D-printers. None of them produces 100% perfect perimeters.

I now have finished a printer of own design. It's casing is a very strong wooden box and that is one of the main reasons it outperforms all previous printers we've built in the past. No more ripple on the perimeters and no more ghosting around holes. As a matter of fact, it was very strange to have these perfect perimeters after 3 years of building and testing printers.
Second reason why it performs so well is that I abandoned these LMUU linear bearings. I make my own (adjustable)bearings. So there's absolutely no play on the axis at all.

Agree totally. The reason Im abandoning my Prusa and switching to a corexy design is stability & rigidity of the frame. I also chose the D-Bot as it uses only v-slot extrusion and wheels. No rods & linear bearings in sight.

[tekkydave]

6 hours ago, Gina said:

I shall be interested in how you get on with PETG filament.  I've looked at it's properties, particularly compared with ABS which is my current favourite filament.  The lack of fumes is certainly a plus point and means you don't need a fume enclosure.  OTOH with the amount of filament I get through cost is a factor.  Also, the ability to use acetone for solvent welding ABS is something I find very useful for making awkward or very large objects.  I'm always on the lookout for different filaments though.

At the moment I only plan to use PETG for the DBot build as PLA is considered too weak/brittle. I may as well build it properly to start with rather than be reprinting bits later.

[Gina]

Yes, that's my thinking too.

[tekkydave]

I've started printing the parts for the DBot on my Prusa. Using PETG at 240C with the print bed at 80C.

I'm printing at 85% infill to ensure I get solid, durable parts. This may take some time

BTW I've abandoned the bowden setup on the Prusa and put the extruder back how it was. I can do 50-60mm/s no problem with only mild vibration effects in the prints.

 

[Chriske]

Done some printing with PETG myself, lots of stringing. Changed slicersettings a few times to no avail...

[tekkydave]

Yes, I'm still getting stringing. I need to calibrate the temperature and retraction before I print any more parts. 

[Chriske]

Like I said, changed a few settings :
lowered printingspeed drastically to 30mm/s, lowered printtemp, enlarged retraction to 2mm, lowered retractionspeed...same result as before...
As I read it, it seems to be very difficult printing PETG without stringing. Maybe some other brand worth trying..?

[Chriske]

Dave,

You should consider using TMC2100 drivers, at least for X and Y-motors. It improves perimeter quality a lot as it uses microstepping. And also quieter movement of the XY-carriage is the result.
If you do buy them take care: they should be mounted reversed..!!

[Gina]

A4988 drivers use microstepping and never had any problem with them but I haven't tried PETG filament yet.  I thought I might try as it doesn't give off nasty fumes but seems it would be easier to finish off my fume extraction systems.

[Chriske]

9 hours ago, Gina said:

A4988 drivers use microstepping and never had any problem with them but I haven't tried PETG filament yet.  I thought I might try as it doesn't give off nasty fumes but seems it would be easier to finish off my fume extraction systems.

Correct Gina,

We never had any problems with these A4988 drivers in the past either, let that be clear. But in the end the result is far better with these TMC2100 drivers.
And maybe, just maybe it also could be a combination of different items I integrated in my own designed printer.

[tekkydave]

First part I printed wasn't great so made a few changes.

• Increased hotend temperature from 240°C to 250°C.
• Reduced the speed from 60 to 30mm/s.
• Increased the retraction from 1 to 1.2mm (at 25mm/s).
• Changed infill from 85% to 70% which is good enough and uses less filament.

These changes have got rid of most of the stringing and are producing nicer prints, at least on parts that are flat to the bed with vertical holes. Now printing some Z-wheel guides which have holes going parallel to the bed - we'll see how they turn out

[tekkydave]

The first two useable prints using PETG. The retraction is now set to 2mm @ 20mm/s. I think I'll try pushing it a bit further even though E3D dont recommend it.

I have also decided to print the parts individually to keep retraction to a minimum.

[tekkydave]

Another tip for Cura users: If you use the 'Concentric 3D' infill pattern it reduces vibrations a lot (on my Prusa it does anyway!). You also get less retractions as a consequence too

I'm forging ahead with the part production and currently printing the 1-Rear_Idler_Right part which is 2.5 hrs into a 5.5hr print.

Cura Parameters:

• Layer Height = 0.28mm
• 3 shells on all sides
• Z Seam Alignment = Random
• Infill = 70%
• Infill Pattern = Concentric 3D
• Printing temperature = 250°C (PETG filament)
• Bed temperature = 80°C
• Retraction = 2.5mm @ 25mm/s
• All speeds = 30mm/s
• Combing Mode = No Skin
• Build Plate Adhesion = Brim (4mm wide)
• Mesh Fixes: All disabled