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.

These are the t-nuts I used

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.

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.

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

14 hours ago, Chriske said:

As I said I'll buy these,

But aren’t these also made in China...?

Yes, but I trust RS as a decent and responsible reseller. The fake I bought on ebay was untraceable really.

Now fitted into D-Bot's Mains Distribution Enclosure. It is a drop-in replacement for the FOTEK although the indicator LED is in a slightly different location and it is overall slightly deeper (front to back).

I made a temporary mod to the front panel for the LED. I'll print another one at some point

I bought a new SSR from a reputable supplier (RS)

Its a zero-crossing type which Duet recommends and is also the correct type to use for mostly resistive loads.

It should fit in the existing case on my D-Bot but the LED will be in the wrong place. A drill should fix that

Looks like I have a fake. I'm only drawing ~3A (750W silicone heater) so theoretically well in spec.

It doesn't even feel warm to the touch in use but I think I'll invest in a genuine part and up the spec a bit.

According to the Duet docs it uses a 10Hz switch frequency for bed in PMW mode so should be fine.

https://duet3d.dozuki.com/Wiki/Choosing_a_bed_heater#Bed_heater_driven_using_a_Solid_State_Relay

Mine is running in PMW mode and has been for 3 yrs. This is the first I've heard about not using SSR in PMW mode!

5 minutes ago, Gina said:

Yikes!!!    I use exactly the same make and model! 

Same here.

13 minutes ago, Gina said:

It's a refractor about a metre FL plus a modified Coronado PST.  Currently on loan from Peter Drew - sale or return.  Project so far is covered in my Blog.

Don't know how I missed that  

I've thought about doing that myself as I have hardly used the 127Mak I bought ages ago now. What solar scope do you have?

A Happy Christmas to all out there especially those on their own. On my second sherry here already and there's a nice bottle of rosé in the fridge for dinner. That's 'Dinner' not 'Luch' as we're in sunny Yorkshire. And it is sunny for a change 😎

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:

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.

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

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.

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

A quick mock-up this morning to check the parts take the existing extruder assembly (motor/motor holder/extruder/piezo).

Looks like a perfect fit. Now ready for those rails

I need to do a spell of nut insertions first (ooeerr  )

Nearly done...

I have been beavering away for the best part of a week designing a new x carriage for the D-Bot. This will allow me to use the same linear rails as I used on the y-axis. There will be rails top & bottom even though my design is balanced with the motor below the 2040 extrusion. I have designed it to re-use some parts of my existing carriage such as the motor holder which also contains the piezo sensor. It also re-uses the belt clamps. I have based the design on the existing carriage which is the Re-X-Carriage by NickRimmer and modified where necessary. I will probably lose about 20mm of z travel but that's not an issue. The D-Bot will go to 300mm in z but I never print anything that high.

Here are the designs from FreeCAD. Front view:

And the Rear View:

The small PCB on top is the Precision Piezo Universal PCB which eventually will have a small cover.

The yellow part is the existing motor holder / piezo sensor. The Titan Aero bolts to the front of it. I should be able to just take this intact from my existing carriage and insert it into the new one

The only parts I need to print are the front & back panels (blue) and the top & bottom block holders (green). I have also added some extra holes on the front panel to take a cable relief (currently being designed) and a filament guide. I may change the filament guide into a filament motion sensor at some point in the future.

The parts are printing at the moment...

7 hours ago, Gina said:

Yes, they are suspiciously cheap but if they last a couple of years they won't cost much to replace.

I've just ordered another 2 for the D-Bot x-axis 😮

18 minutes ago, Gina said:

Yes, they are suspiciously cheap but if they last a couple of years they won't cost much to replace.

I discovered the easy way to install these is to put M3x8mm bolts through 4 of the holes with proper t-nuts attached (not square nuts). You can then just align the nuts and push it onto the V-slot. Turning the M3 bolts will then turn and tighten up the nuts.