tekkydave

Yes, I think you're right; the x carriage needs sliders above & below. There is no adjustment built into the rails/sliders themselves. I'm currently using the Re-X Carriage by NickRimmer which is designed for the D-Bot & Titan Aero. I also use this alternative motor mount to hold my piezo device.

There isn't a rails version of this so I will have to design my own.  Could be an interesting FreeCAD project. I'm gradually getting more proficient

24 minutes ago, Gina said:

WOW!!  That is a wonderfully flat bed.  My Concorde bed seems to curl up on one corner by a few tenths of a mm!

Are you using the new linear rails for all three axes now?

No, just the y axis. The x axis has 4 wheels and the z has a 3-wheeled carriage at diagonally opposite corners.

Having a go at printing something; some amended parts so I can reinstate the y-axis optical endstop.

The printer overall is quieter. The old y axis seemed to amplify any vibrations for some reason.

Also the mesh compensation map is better. Before there were dips at the corners despite the bed being rigid. I concluded this was due to some springiness in the 3-wheeled y carriages. It is almost dead flat now.

55 minutes ago, Chriske said:

Why not print these two overhanging parts separately and bolt it together with the main body.
As you're doing it now there's lots of support needed. Wonder if you're be able to remove it easily.

I agree. It would make the overall assembly stronger and give you more flexibility. When printing the main part you could add several sets of holes to allow the other 2 parts to be moved along the axis of the dovetail.

Also If you need to alter the 2 smaller parts in the future you wont have to print the whole lot again.

1 hour ago, Dr_Ju_ju said:

My experience, with my Mk2, is that the quality of the print, stays the same whatever mode is selected.

Quality, also relies heavily on the slicer used; for me its either Simplify3d (Paid for) or the preferred PrusaSlicer (free). I have multiple profiles configured for printers\filaments etc. which means I can usually send the print to any of my printers, depending on the size of object etc.

I have been using Cura for about 6 months having used Slic3r 1.3 dev for a long while before that. The latest releases of Cura seem to produce inferior results so I tried the PrusaSlicer again last week. Much better results so I have switched to that. It has come a long way since being forked from the Slic3r project - well worth another look if you are in the market for a different slicer.

11 hours ago, Gina said:

Interesting but the Prusa printer is quite different from mine and indeed from the D-Bot so the comparison may not be valid.  OTOH there are situations where a rigid construction can produce conflict as the system is constrained in more than one way at a time.  Pretty much what he said in fact.  I need to think about all this.  I guess some flexibility is needed somewhere.

There is still a small amount of 'give' in the D-Bot y-axis even with a rail on both sides. This is with no belts fitted. Maybe this is less on the better quality rails. I don't think the ones I have fitted are of the highest quality - that costs £££

Once the belts are fitted and correctly tensioned there is no discernible play. I haven't printed anything yet 😮

I'll have to see if it makes any noticeable difference to print quality. I think the mini v wheels are starting to wear. I got black dust out of some of the ones I took apart today.

I want to do the x-axis next then possibly the z too. The printer needs rebuilding as some of the sections are no longer 100% square or parallel. If I rebuild from scratch I'll do the z axis at the same time. The 3 z motors need better mounts in the base so lots to think about.

I have replaced the mini-v wheels on the y axis with linear rails. I used the printed parts from here and used these MGN12 rails.

The reason the rails are on the underside is that how the thingiverse parts are designed. If it is an issue I can swap them but I will need to shorten the rails by 20mm.

I also took the opportunity to replace the GT2 belt and idlers at the same time.

Movement seems to be a lot smoother and the mesh levelling has improved. I now plan to do a similar thing to the x-axis once I have designed some parts.

Holes always come out slightly smaller than expected due to the extra thickness of the filament. When designing its good to increase the size slightly to compensate. e.g. I always draw 5mm holes at 5.4mm and an M5 nut will just clear the sides when inserted. Obviously doesn't help you with this as someone else designed it. I find a round needle file is my friend in these cases. Might be worth buying a set for the future

Good to see you are getting on well with the new printer  - much faster than when I first started out in 2014.

2 hours ago, Gina said:

My interchangeable hot ends consist of Precision Piezo Z probe unit, cooler, heater block with heater and thermistor plus 4 wire connections.  To swap I remove the 4 screws from the front of the E3D Titan extruder and swap hotend plus filament guide.  Not quite as easy as Chris's system but best I could manage with what I have.

My piezo is embedded in the motor mount so I didn't have to worry about that bit fortunately. I use 1.75mm exclusively now so no more swapping about

When I was using both 3mm and 1.75mm filaments I did interchangeability by swapping the front of the Titan Aero. You need 2 fronts and complete heatbreak, block, heater, thermistor & nozzle assemblies. All the wires need inline connectors too but it can be switched in a couple of minutes.

10 hours ago, JamesF said:

I am just starting to print out my first attempt at a case for my Robert Brown dew heater controller.  Also my first design made in FreeCAD, though I stuck with the solid geometry workbench that's more similar to OpenSCAD rather than using the sketch-based workbench.  It wasn't too hard once I got the hang of the controls.

James

I'm getting more proficient with FreeCAD and have designed several parts so far. I'm mostly using the Part Design workbench. It's the closest to what I previously used which was Sketchup. I do get occasional crashes so saving often is a good idea.

Finished!

The print was firmly stuck to the PEI sheet at the end of the print. I couldn't pull it off. Not that I would ever want to do that.

Removed the steel sheet from the magnetic build plate and flexed it a few times and.... pop... off it came.

The base isn't as shiny as with glass but its still quite a nice satin texture.

I'm OK with PEI so far and the magnetic bed. I just don't like the look of the PEI sheet supplied with the kit. I'm going to look for a steel sheet with PEI already applied I think. Black would be nice

The part is a hook that sits inside our pull-out rubbish bins in the kitchen in case you were curious   Not the best print I've ever done but still getting my Cura settings right.

Printing now. I cleaned the PEI surface with what I normally use for glass :- Soap & warm water

PLA seems to be sticking quite happily to the surface so far....

I read online that it is good to rough-up the surface of a new PEI sheet with wire wool prior to first use. Any truth in that PEI fans?

13 hours ago, Gina said:

I tried a PEI sheet - total disaster!  Filament sticks better to clean glass when hot and releases nicely when cold.  The hot nozzle burnt the PEI when Z homing using the Precision Piezo Z probe.  I ended up removing the PEI sheet and then struggling to get the goo off, though I managed it in the end. 

How hot is your nozzle when probing? I have mine at 130 as it is soft enough to squish any filament on the nozzle.

11 hours ago, Chriske said:

I have several sheets of glass for each printer.
When a print is done I remove sheet + sticking part and install a fresh sheet of glass and continue even before the alu printbed is cold.

How do you secure the glass to your bed? I have a gap of 20mm on the L & R sides of the glass, 30mm at the back and 10mm at the front. Foldback clips are not suitable. I like glass as a surface but since I increased the size of the bed from 300x300 to 340x340 its become an issue securing it physically.

Because of the size of my bed (340x340mm) it was proving hard to keep it clamped in place. The glass is 300mm square.

I now effectively have a magnetic bed so I can try other solutions if not happy with the pei sheet that came with the kit. It is also possible to print directly on the steel sheet so I can flip it over and give that a try.

I thought I would ditch the borosilicate glass and try a magnetic PEI sheet.

So I bought one of these

I removed my bed from the D-Bot to make it easier to apply and gave the surface a good clean with meths.

The first part to apply is the magnetic base which sticks to the metal bed

The best method is to score the backing with a sharp knife so the first quarter can be peeled off separately and stuck down. Then clamp it to the bed so it can't slip.

Then peel off the last quarter and stick down carefully avoiding any bubbles.

Then remove the clamps and stick the remaining three-quarters down

The next part is the steel sheet which sticks to the magnetic sheet very well. The small tabs at the front are needed to prise it off the base.

There is a yellow PEI sheet to stick to the steel sheet. I followed the same procedure as with the magnetic sheet.

There are a few tiny bubbles on the left side of the sheet which I'm hoping will smooth out when I heat it all up.

The PEI sheet was slightly larger than the steel sheet by a few mm each side so that was trimmed off.

Finally the plate was fixed back to the z-carriage and connected back up to the controller

I'll have a go at printing something tomorrow and report back.

Decided to recalibrate my E steps/mm for the Titan Aero. PETG in particular seems to be still over-extruding after the switch from 3mm to 1.75mm filament. I currently have it set to 419 steps/mm which is what E3D recommend as a default for a 1.8deg motor and 16x microstepping. It worked fine with 3mm/2.85mm filament.

I removed the hot end parts from the Titan and extruded 100mm of filament - it measured at 104mm.

So:

New Steps/mm = (419 x 100)/104 = 403

Issued an M92 E403 to the Duet.

Tried the above procedue again and got 100.5mm extruded

(403 x 100)/100.5 = 401

Put 401 in the M92 command and now it extrudes 100mm every time.

I put this down to the diameter of the hob being different for the different sized filaments due to it contacting them in a different part of the profile.

Just shows you though - don't just go with the manufacturer's default value - test it yourself 🙂

26 minutes ago, Gina said:

1.75mm filament melts more easily due to geometry - more surface area compared with volume.  Also, 1.75mm filament is more easily controlled as it goes through the extruder faster for the same volume of print.  The chemical composition of the different sizes of the same brand and colour should be identical.  The difference you are noticing between 3mm (or 2.85mm) and 1.75mm filament is well known.

I thought the geometry would be the most likely explanation. Some of the "3mm" filament I had was actually 3mm diameter. I've had 2.85, 2.9, 2.95 and every other value between 2.85 and 3

17 minutes ago, Gina said:

The CAD software is interesting.  I'm using a Windoze only CAD software running in VirtualBox with Linux Mint (a fork of Ubuntu).  This is a very old version of Autocad Inventor and very powerful though I have found the odd problem.  No doubt this applies to any software. 

Duet was the best upgrade I have applied to my printers.

I thought you were using Sketchup.

Ok, these updates are getting more infrequent. It's not that I'm not doing stuff, just that it's probably not newsworthy.

The last few months have been pretty busy as we have had our kitchen done. I'm hoping to spend more time on projects now but we'll see what happens there

The only major change I have made to the printer, apart from keeping the Duet software up to date is a complete switch from 3mm to 1.75mm filament.

The main issue with 3mm was getting it to load into the Titan Aero easily. The filament path in the Titan is quite 'tight' and the filament often needs to be bent against its natural curl. No problem with PETG as it is naturally more pliable than PLA. But some PLA filament is definitely brittle and I often ended up taking the Titan front cover off to clear out the tiny bits after it had shattered (the filament not the Titan  ).

The 1.75mm PLA and PETG I have now loads very easily so no more swearing during colour/material changes.

One thing I have discovered is that I need to reduce the hot end temperature for 1.75mm filament. For example I have some 3mm and 1.75mm REAL PETG. The 3mm prints best at 250C but the 1.75mm at 240C. Maybe the 1.75mm can heat up quicker in a narrower melt zone or it could be any number of things:

• The 1.75mm is physically different to the 3mm filament despite being the same Supplier & Brand.
• The hotend thermistor was replaced at the same time so maybe reporting a different temperature.
• Something else I haven't considered.

I wonder if anyone else has noticed this effect or is it just a quirk of the filament.

I've also decided to learn a different CAD package. I have been happy using Sketchup for the last 5 years despite the bad press it gets. It has served me well personally and I will still need to use it from time to time for editing existing models.

I don't use a Windows PC which restricts me to the older 2016 version. I run it in a Virtualbox VM and the 2017 version refuses to play ball. Also they will not be releasing any more free versions apart from the 'Sketchup Free' which is web based. I have tried it and it is slooooooooooooooooooooooooooooooow....

I tried Fusion 360 but it also only runs on Windoze so was much slower than SU in the same VM.

So I have started learning FreeCad which runs on the Ubuntu Linux I use on my main PC. It works a bit differently to SU but after following an online tutorial and playing around for a couple of hours it is quick to pick up. It is also truly FREE being open source. It seems to have more modelling features than SU and doesn't need loads of add-ons installing just to export to STL or add a fillet/chamfer.

All my 3D printing workflow is now Linux based:

FreeCad --> Cura --> Duet Web Control (browser-based).

If it helps at all I bought This VA panel meter and worked out the following wiring scheme. The included instructions were very poor.

This is a good step-up converter. I used one in my now defunct prusa 3d printer to provide 12V to the extruder fan from the ATX PSU 5VSB line.

In case anyone is unaware of AppImage and how it works see this explanation.