Prusa i3 3D printer

[tekkydave]

Tried 9 points (3x3) but no difference. I have adjusted the bed manually to be almost perfect and the ABL seems to be better. Also adjusted the Z_PROBE_OFFSET_FROM_EXTRUDER from -13.4 to -13.6 and it seems to be the correct distance now as  measured with a piece of paper.

Going for another test print...

[Gina]

Yes, I found ABL to be better with the bed almost level.  I think it's a matter of how much Z movement is required

[tekkydave]

I think I went too far with my z offset adjustment. Once the bed was heated the nozzle was way too close to the bed. The filament was being squashed into a thin ribbon on the bed. I'll have to adjust back the other way. I think I also need to set up a failsafe endstop switch for the zaxis. Its too easy to crash the hot end if you try to move it manually before homing. The old z endstop is still fitted so I'll connect it in series with the switch on the probe and arrange it just below bed level. It will get triggered if the nozzle pushes the bed down on its springs. Work tomorrow so enough for now.

[Gina]

Ah yes, I was thinking of adding a microwsitch to the sprung bed or indeed, yes, a normal Z endstop that would operate at the appropriate height - that would be better.

[tekkydave]

Bought some spare linear bearings http://www.amazon.co.uk/dp/B00SAHCVNE/ref=pe_385721_37986871_TE_item

[tekkydave]

I was having some trouble with the x axis belt tension. The tensioning arrangement on the supplied idler was not ideal and kept slipping. It was also bending the idler plastic. I decided rather than print an entire new idler part to design a clip-on attachment to allow the idler bearing to be moved in/out using a screw mechanism, similar to the one I fitted on the extruder.

The current arrangement

Here is the sketchup design.

The printed parts

Fitted together showing the range of adjustment (assembly is on its side)

Fitted in place on the idler. The circled area shows how the clip is kept in place

The belt tension is now much easier to adjust and it also runs much smoother as the idler bearings now rotate correctly.

[tekkydave]

Wow, it's over a month since I last posted anything. Last weekend I added some extra wires to the D37 cable for the ABL servo which was still wired to the control box directly. At the same time I decided to add some extra wires whilst I had the connectors apart for:

12VSB

5VSB

The remaining pins were wired as Spares.

I'm not sure what I will use the 12VSB and 5VSB for at the moment but they are there if I need them.

Today I wired up the control box ends of the above to the D37 on the front panel and also the ABL servo to the D37 at the printer end.

Here is the final wiring schematic. The signal column colours represent the wire colours and the pin column colours correspond to a heatshrink around the groups at both ends of the D37-D37 cable. These were added when I was wiring it up to make it easier to identify the component.

It has taken quite a lot of effort to complete the control box but definitely worth it. If I build any more printers I can quickly switch the box from one to another for testing.

[Gina]

That's a thought   Though I'm not that sure it would be worth it   Anyway, I have this habit of running two printers at a time - multitasking printing operations

[tekkydave]

That wasn't the main reason for the way I built it. I wanted to be able to have it separate from the printer so it could be placed out of the way or under the desk etc. If I did use it with another printer it would only be a temporary thing for testing then I'd build a dedicated controller.

[Gina]

Ah yes - I seem to remember that from way back

[tekkydave]

I decided to print a fan duct for print cooling ( I already have one on the hotend heatsink). I have read that cooling PLA prints can improve them greatly. I found this one on Thingiverse which combines the two http://www.thingiverse.com/thing:839620

Screen print from Octoprint:

[Gina]

Nice to see you around again Dave   I made a print cooling fan spout for the Velleman a few years ago - can't find it now.

[tekkydave]

Thanks . I've had lots to do since finishing work but not on the 3D-printing side.

[tekkydave]

All I need now is a 40mm fan. Just realised the one on the hot-end at the moment is a 30mm one! ebay here I come.

[tekkydave]

Print completed ok. I did it slowly (40mm/s) so it took just over 2hrs. I'll fit it when the fan arrives.

[ChrisLX200]

Well the cooler made the single biggest improvement in my prints amongst all the other tweaks to settings, and this was for ABS. I'm currently doing a test print in PLA to see what the difference there is. I have a lot of STL files for stuff I wanted but I simply couldn't get them to print properly - especially anything with bridges.

ChrisH

[ChrisLX200]

Oh, and the fans I bought were these: http://www.ebay.co.uk/itm/191458206299?_trksid=p2060353.m2749.l2649&var=490546671912&ssPageName=STRK%3AMEBIDX%3AIT and they work well (had to be 24V for my because the fan is connected to the MB and controlled through Simplify3D).

ChrisH

[tekkydave]

Well the cooler made the single biggest improvement in my prints amongst all the other tweaks to settings, and this was for ABS. I'm currently doing a test print in PLA to see what the difference there is. I have a lot of STL files for stuff I wanted but I simply couldn't get them to print properly - especially anything with bridges.

ChrisH

Thanks Chris. It was your post yesterday that made me think about trying it on mine

[ChrisLX200]

;-)  My favourite test piece was a T-Rex skull and to date I've done 3 now which are all pretty much rubbish. It's a complex piece and especially the teeth end up a melted mess. So I quickly set up the printer with the cooler running and started the print, came back hours later and it didn't seem to have got very far - then realised it was set for 0.1mm layer and 75% infill from last time. Oh well, it's only fillament... Can't stop it now so will have to wait! :-)

ChrisH

[tekkydave]

 

The 40mm fans arrived yesterday so tried fitting it. It doesn't fit with the extruder I'm using so I think I need to design my own.

[ChrisLX200]

On 21/01/2016 at 17:59, ChrisLX200 said:

59 minutes ago, tekkydave said:

 

The 40mm fans arrived yesterday so tried fitting it. It doesn't fit with the extruder I'm using so I think I need to design my own.

 

I've just this minute finished printing a new cooler because, whilst the previous one was very effective, it was a compromise to make it easier to print (but it didn't cool from the rear or sides - just blowing air in from the front). You could see the effect of that with the some areas being printed much better than others. The best cooler I simply couldn't print before, it's a bit chicken and egg - you need a good active cooler in order to print the cooler! Anyway, using the one I had I printed the one I really wanted ;-)

This was the simple version at work, and as you can see only designed to blow from the front:

 

This is the new version hot off the printer (literally) which blows from both sides and gets around the back too:

I also wired in the fan to the motherboard so it can be controlled from software (Simplify3D) but have yet to figure out how to leave it switched on for a few minutes at the end of the print - some sort of macro I guess. It's printed from ABS but the nozzles are very close to the hot end so if the fans just switch off immediately then it's subject to pretty high temperatures until it all cools down.

ChrisH

[fireshipjohn]

Hi Chris,

You need a bit of GCode in the post print section something like:

M106 255 # Fan on max speed

G4 P60000 # Pause 60 secs

M107 # Fan off

John

[fireshipjohn]

Hi Again,

Apparently you can use:

G4 S60 # Pause for 60 seconds

Seems a bit more useful!

John

[ChrisLX200]

Thanks John, I'll try that shortly!

ChrisH

[ChrisLX200]

OK well I tried the first prints with the new/improved active cooler and it works a treat. A flawless ABS print with no warping. One of these things should definitely be standard equipment.

ChrisH