D-Bot 3D Printer

[tekkydave]

All the nuts & threaded inserts fitted with the help of my hot air gun. Also fitted the x endstop.

 

[tekkydave]

I have managed to get it all fitted together and working. There is a small issue with the front & back panels not sitting flush with the end panels. I needed to put some shims in temporarily to get it all fitting. I'll make some alterations in due course.

The cable relief and piezo pcb mounting are also temporary.

 

[tekkydave]

I redesigned the top & bottom block holders to eliminate the spacers. I've also fitted a new hotend fan. This Noctua NF-A4x10 FLX fan is almos silent. It's the same fan as supplied with the Titan Aero Gold. Now the loudest thing is the PSU fan. I think I'll get a 60mm Noctua fan for that too

 

Edited December 6, 2019 by tekkydave

[tekkydave]

I bought a 60mm Noctua fan for the 24V 15A PSU to quieten it down a bit. It is 25mm thick so won't fit inside the case. So I fitted it to the outside with a 60x60mm wire guard (not fitted in this pic). I had to cut out the hole in the case to improve the air flow. I already had a 20 ohm wirewound variable resistor in series with the old fan so I left it installed. Even on full speed the new fan is much quieter but reducing the speed down makes it silent. I'm only drawing a few amps so it doesn't need much cooling.

I also changed the Noctua 40x10mm fan on the extruder heatsink to the 40x20mm model. The 40x10 wasn't cooling the heatsink as much as I would like - it was warm to the touch. The 40x20 is just as quiet but has a higher static pressure - keeps the heatsink cold.

 

Edited December 18, 2019 by tekkydave

[tekkydave]

I've also been trying to design a better extruder carrier with built-in piezo module. My existing one has a 27mm piezo disc set in a slot between the motor and extruder. It has to be pierced to allow the motor shaft to pass through and relies on a 'hinge effect' to compress the piezo.

I want to create a better design using a Precision Piezo Andromeda module. These are mainly for underbed use but can be used in any application where the ends are fixed and the centre is flexed. I designed a new motor carrier with slotted mounting holes so it can move up/down when the nozzle makes contact with the bed. The Andromeda sits across the gap at the top with an M3 screw projecting up slightly. This makes contact with the part above flexing the module. It works ok but not very smoothly and there is some scope for the moving motor carrier to rock as well as move up/down. I planned to put 4 springs in the holes in the top but don't have any suitable.

I have ordered some MR63ZZ 3x6x2.5mm bearings to see if I can restrict the movement to vertical only.

The prototype showing the location of the piezo module and slotted mounting holes:

 

[tekkydave]

I've created an updated version of the motor holder for the Andromeda module. Rather than having the whole motor holder slide up & down I have printed it with fixed mounting holes. I also used a fairly low density (20%) concentric infill. This gives it a good degree of strength front to back where it is mounted but also a slight flexibility up/down. The Andromeda module is also mounted in a slot instead of by fixed screws as before. This makes it easier to remove/re-insert for adjustments.

It works very well although I need to get a proper M3x8mm screw for the trigger - at the moment I have a cropped down M3x10mm installed as it was all I had. The 8mm are on order

 

[Dr_Ju_ju]

quick question for you, as you are using a thick cast bed, have you fitted a different thermistor\PT1000 etc. to the bed to cater for the latency in heating the whole bed surface, or do you just put a delay into the gcode ??

[tekkydave]

12 minutes ago, Dr_Ju_ju said:

quick question for you, as you are using a thick cast bed, have you fitted a different thermistor\PT1000 etc. to the bed to cater for the latency in heating the whole bed surface, or do you just put a delay into the gcode ??

No, at the moment I'm still using the thermistor embedded in the silicone pad. I intend to fit another thermistor directly to the bed at some point. I usually let the bed heat up for a few minutes before printing but it's a manual process at the moment.

[Dr_Ju_ju]

Same as me then.

Currently I'm leaving it 8 mins to stabilise over the bed area, which is a pain... I'm trying to use M300 to play a beep to alert me, but that just results in a weedy noise out of the PanelDue, so as well as a different probe, I'm also looking at using E1 as an output to drive either a small loudspeaker or piezo beeper, especially as it's PWM control.... 

[Gina]

@tekkydave  I'm building a new printer using the Mini High Accurate Linear Rail like you have used I believe.  I'm looking at mounting the rails.  The description say these are mounted with M6 screws

Quote

Installation screw size(not included): M6(Rail), M3(Block)

but the holes in the rail are much smaller that M6 and even smaller than M4 but larger than M3.  So what I'm wondering is how you mounted the rails.

Thanks.

[tekkydave]

38 minutes ago, Gina said:

@tekkydave  I'm building a new printer using the Mini High Accurate Linear Rail like you have used I believe.  I'm looking at mounting the rails.  The description say these are mounted with M6 screws

but the holes in the rail are much smaller that M6 and even smaller than M4 but larger than M3.  So what I'm wondering is how you mounted the rails.

Thanks.

I used M3 bolts (8mm I think) with M3 T-nuts in the v-slots. M6 can't be right.

[tekkydave]

These are the t-nuts I used

[Gina]

 

Thank you.  I'm not using V-Slot but an 18mm thick plywood box.  The rails will be bolted to the box sides.

[tekkydave]

Ok. The holes in the rail have a counterbore that a standard hex cap bolt head will sit in. So they won't foul the block running across the top.

[tekkydave]

You don't need a bolt in every hole - I have one every fourth hole and it is well secured to the extrusion.

I think I need to get a dust cover for my printer though

[Gina]

Yes, I too have wondered about a dust cover for when I'm not using the printer (rare).

Measured the rail holes and they were just over 3.5mm so I'm thinking of getting M3.5 bolts and nuts though I have some M3 nuts & bolts I could use to get going.  Probably not enough though.

[Gina]

I can't find M3.5 bolts so it will have to be M3.  Haven't got any long enough so just ordered some M3x30mm from Amazon due to arrive Monday.

[Dr_Ju_ju]

FYI Info Dave, to get a more accurate Bed temperature reading, I decided try a different Thermistor that would be easier to mount at the edge of the bed to cater for the thermal latency in the thicker bed, but otherwise of the same spec as the one that came fitted to the mains powered heating pad.

A quick search through Farnell and I came upon an Epcos Thermistor, that can be bolted down, and has the same spec. (https://uk.farnell.com/epcos/b57703m1104a002/thermistor-ntc-100k-wire-leaded/dp/2672684?CMP=i-bf9f-00001000) so I thought I'd give it a go, as they aren't too expensive, just have to watch the shipping costs.

 

I did a quick lash-up \ test and was glad that the device could be easily integrated. So I bolted it onto the bed plate using the same bolt that I've already fitted to connect an Earth safety bond, and spliced it into the existing wires.

 

A quick M303 to tune the Bed heater and I was away.... 

It is still a slow process to heat the bed (all that metal, 10mm sheet), but at least I'll know that the bed has reached the appropriate temperature at the edges, even if it is a few degrees warmer towards the centre... 

 

 

[tekkydave]

Well spotted. I might get some of those

 

[Stub Mandrel]

I put a layer of ceramic thermal wadding under my bed and it heats up nearly twice as fast. Just lying a sheet of A4 on top speeds it up even more, but make sure you don't leave it in place... in the long term I might make a full enclosure.

I'm printing the first prototype mirror holder for a mirror cell, using Monoprice PLA+ which is printing beautifully, no change to settings.

To print the other parts of the cell I need to extend my Y travel 35mm to use the whole of my bed, so I've ordered a couple of 8mm rods and some M10 studding.

Just realised I need a longer toothed belt 😞

[tekkydave]

14 hours ago, tekkydave said:

Well spotted. I might get some of those

 

2 on order

 

[Dr_Ju_ju]

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