Prusa i3 3D printer

[tekkydave]

Great quality prints, Chris.

[ChrisLX200]

Thanks Dave, this is another item I could not print before, small pully wheels for a toothed belt about 1" diameter - tried many times using both PLA and ABS. Those 3 fails at the back (PLA=Red, ABS=Blue) is what happened without a cooler fitted, after mucking around with temperatures and speeds still no joy. The top edge was too thin to print without active cooling. The two new ones (in ABS) I just printed now - perfect.

ChrisH

[Gina]

What an amazing difference!  Food for thought   Going through my boxes yesterday I found the air duct I made for the Velleman - it uses a 40mm fan.  When I get back to playing with 3D printers I shall see if it fits OR I can design an alternative.

[ChrisLX200]

Give it a try Gina, and if you need to design another (though you'll likely find something suitable on Thingiverse) then make one that blows air around the sides too.

I just got delivered some flexible filament to play with, I need to make some compressable waterproof seals so I thought I'd give TPE a trial (Ninjaflex is way to expensive).

ChrisH

PS. Apologies to Dave for hijacking his thread!

 

[fireshipjohn]

Hi Chris,

That's interesting. Inspired by this thread I bought my own i3 (same one as TekkyDave ) and I've been using it quite happily for the last 3 months. I have printed the same type of pulleys as you show in PLA and never had a problem like that, I have added a cooling fan, but I found it didn't make any difference so I leave it off. Your early pulley prints look like they are way too hot?

 

 

 

 

 

 

 

 

Have you tried something like this: http://www.thingiverse.com/thing:217793 - thats for PLA and takes some fiddling to enter the temperatures, but its very useful to see the temperature effects. After doing this I knew my PLA temperature should be 190. You can see the difference 5 degrees makes. 

John

[Gina]

Here are some photos of the cooling air duct I made for the Velleman printer which has now become my Pilot printer.

[tekkydave]

I decided to have another go at producing a cooling fan to improve print quality. I found this on Thingiverse http://www.thingiverse.com/thing:540716 so printed up a nozzle and a selection of parts to experiment with. I needed to design and print a new part (highlighted with red ring) to attach it to my extruder.

Now I need to work out the best configuration of parts to get the fan and nozzle in the best position.

I also connected the D9 output on the RAMPS from the control box through to the printer. This will give PWM control of the fan speed using the M106 & M107  g-codes:

M106 Sn (n = 0 to 255) - Turn fan on with speed n.

M107 - turns fan off (equivalent to M106 S0)

 

 

[mapstar]

Amazing stuff Dave I take it the fan moves with the printing head above the heated bed? Just a thought could the fan be mounted remotely and the air ducted in using 6mm hose or similar? 

[ChrisLX200]

A different question - looks like your glass bed is a mirror, is it a mirror tile perhaps? I've broken/chipped 2 sheets of 3mm borosilicate glass so far and they're not cheap to replace! I think I've got a strategy to avoid more damage but I'm still looking for alternatives..

ChrisH

[tekkydave]

20 minutes ago, mapstar said:

Amazing stuff Dave I take it the fan moves with the printing head above the heated bed? Just a thought could the fan be mounted remotely and the air ducted in using 6mm hose or similar? 

Yes its quite light so no real problem. I suppose it could be fed remotely - I never really thought about it.

[tekkydave]

19 minutes ago, ChrisLX200 said:

A different question - looks like your glass bed is a mirror, is it a mirror tile perhaps? I've broken/chipped 2 sheets of 3mm borosilicate glass so far and they're not cheap to replace! I think I've got a strategy to avoid more damage but I'm still looking for alternatives..

ChrisH

It came with the kit but it's not a tile. Not sure if these are special glass or anything but they work well. I have only used PLA so far. Supplier is http://semiu.co.uk/product/mirror-glass/

[ChrisLX200]

OK, thanks Dave. I can't see there being anything special about the mirror glass they provide, they hardly make their own do they! I need to look out for some 230 x 160mm (which has been my problem sourcing alternatives - the odd size).

ChrisH

[tekkydave]

I noticed that a new RC version of Marlin was available on Thursday (1.1.0-RC3) so decided to try it. I modified the configuration.h to suit and uploaded it to the Mega. It failed on the auto bed levelling as the z-probe servo didn't deploy and the nozzle crashed into the bed. No damage done but I decided to put RC2 back and leave for another day.

Started looking at the Marlin website and the code today and realised the default value of MOTHERBOARD has changed. Previously if you put:

MOTHERBOARD BOARD_RAMPS_13_EFB

it meant a Ramps 1.3 or 1.4 board. From RC3 there are separate options of BOARD_RAMPS_13_EFB and BOARD_RAMPS_14_EFB but it defaults to the BOARD_RAMPS_13_EFB value.

The servo 0 pin used to deploy the z probe is different between these 2 boards which must be why it didn't deploy. I have a v1.4 board so it was trying to use the wrong configuration.

This has been chamged so the default is now BOARD_RAMPS_14_EFB in RC4 which was released yesterday. I'll have another attempt after the weekend and see if that fixes it.

 

[tekkydave]

I have now got Marlin 1.1.0-RC3 working on my printer. As suspected the reason the probe wasn't deploying was down to it defaulting to the RAMPS V1.3 pin layout whereas my board is a v1.4. One of the pins that differs is the one driving servo 0.

All I had to do was change the line

#define MOTHERBOARD BOARD_RAMPS_13_EFB

to

#define MOTHERBOARD BOARD_RAMPS_14_EFB

Re-uploaded and the z probe on the servo now deploys.

BTW I also just learned that the 3-letter combination at the end of BOARD_RAMPS_14_EFB denotes the configuration of extruders, fans and beds on the 3 mosfet outputs D8, D9 and D10 on the Ramps board.

EFB = Extruder, Fan, Bed (my current config)

EEB = Extruder1, Extruder2, Bed ( if you have 2 extruders)

or even

EFF to have an extruder, 2 fans and no bed. presumable for those who don't use a heated bed or control it some other way.

Next task is test the 1.1.0-RC4 release....

 

 

[Gina]

I use the EEB version as I have two extruders on both my Pilot and Titan though not yet used two extruders in the same print.  I'll sort that out one day   If I add a print cooling fan I'll have to add in the control for that.  I'm intermittently working on my Pilot printer lately but the Titan hasn't been touched for weeks.  Both need work on them.

Have you found any improvement in Marlin over the RC2 version (which I'm using) Dave?

[tekkydave]

I haven't tested RC3 printing anything. I just checked the basic movement, end-stops and ABL worked correctly. I'm going to skip to RC4 now so currently editing the configuration.h. I'll do a test print using that and report back later.

[Gina]

Thanks Dave

[tekkydave]

There is a problem in RC4. It seems to stall at the start of a print; after the ABL but before actually printing anything. It is getting to the M109 command and just sitting there. The problem is definitely only in RC4. I tried RC3 again and no issues. The problem in RC4 seems to occur when starting a print once the hotend has already been heated up. If I print something from 'cold' it works fine. It is around the M109 command that the problem occurs.

Anyway I'm sticking to RC3 for now

 

[tekkydave]

I made another couple of minor mods this afternoon.

1. I wanted to set up a z-axis endstop to trigger if the endstop on the servo fails to deploy for some reason. I had already printed and installed a bracket on the left-hand z motor for this. I connected a microswitch in series (they are connected normally-closed) with the one on the servo and tie-wrapped it to the bracket. I knew the microswitch arm wouldn't reach the z-axis adjustment screw so I soldered a strip of metal on it to make it longer. Then I adjusted the screw to trigger the switch if the extruder nozzle is pressing down on the print bed. This only works during homing but it's an extra level of failsafe.

2. I also adjusted the values in the Marlin firmware to stow the z-probe servo to the rear rather then the front. This is to make more room for the cooling fan when I get it sorted.

 

[tekkydave]

Marlin 1.1.0-RC5 was released last week and claims to fix the bug I found in RC4. I flashed the Mega and did some testing. It seems to be bettet but still stalls, but only when I have already set the hotend temperature manually. I have changed the way I work to turn off the hotend power before starting the print. This allows the gcode to set the temperature and wait which seems to work fine. Not sure if this is a bug or just the way it works now but it's no problem. I have stuck with RC5 for now and it seems ok. Anyone upgrading from RC3 or below note that some of the options have been reorganised/renamed so read the release notes and edit the configuration.h carefully.

I decided to switch to some yellow filament I bought a few months ago. The white I was using always gave good results but the yellow didn't extrude properly. The white was ok at 200C but I needed to push the hotend to 225C for the yellow before it would flow well. It was also underextruding so I investigated the extruder. I noticed it stopped extruding when the large cog was in the same position each rev. The hobbed bolt isn't the best in the world and the yellow being slightly narrower than the white (2.85mm instead of 3mm) was slipping off the hobbed area onto the smooth part of the bolt. I took it all apart and reassembled with less play in the bearings. It then extruded ok. It works for now but I think I need to buy or make a better one soon.

So, now I had it working I printed a case for the LCD controller. I found this one on Thingiverse http://www.thingiverse.com/thing:124613 which fitted the bill.

This is how the first layer came out when the yellow wasn't extruding. You can see there is a repeating pattern in the under-extruded areas.

And here are shots after I got it working

The completed print

It fits!!!

I'll complete the assembly tomorrow.

 

 

[tekkydave]

I realised this morning that the rear half of the lcd enclosure had been printed wrong. I thought I had turned it over in Slic3r but I must have flipped it instead of rotated it. Consequently it had ended up mirror-imaged. So, I had to reprint it correctly.

The incorrect (mirrored) parts showing incorrect positioning of two halves of SD slot.

And with the reprinted rear half. Now correct.

And the finished item with 2 halves screwed together. I had to drill the hole for the control-knob slightly larger to accomodate the supplied part.

 

[tekkydave]

Now I have fixed the mechanical issue with the extruder it seems to handle the green PLA I have had trouble with before. I printed these two bearing holders for making my own hobbed bolts yesterday afternoon.

They take a 608ZZ bearing and support the bolt you are hobbing whilst allowing it to turn. Here is a youtube video showing how it is done.

 I have some M8 x 70mm bolts and a drill press and I have ordered some taps.

[tekkydave]

The taps I ordered arrived today so I had a go at making my own hobbed bolt.

I took the existing bolt out of the extruder and put in a new one. Then marked the position of the filament on the bolt.

Then I followed the method in the you tube video to put  the hobbing in the right place. I started with a 5mm tap. It was a bit difficult to keep the tap in the right place due to the bolt being threaded along its full length. I ground a slight groove with an angle grinder which made it easier. I had the drill press running at its slowest speed of 50 RPM. After a while I switched to a 4mm tap to try and get a deeper groove. I got a fairly decent result for a first attempt despite it being a bit messy round the edges. Anyway I put the bolt back in the extruder and gave it a try.

It works quite well and possibly better than the supplied one which is a bit worn and lop-sided. It pushes the 3mm PLA very well, digging in a bit but not too much.

I've ordered some more bolts that are only part threaded and I'll have another go with those.

 

[ChrisLX200]

For future reference... a helical machine tap would have been better for this job rather than the straight-flute taps you have there.

ChrisH

[tekkydave]

9 hours ago, ChrisLX200 said:

For future reference... a helical machine tap would have been better for this job rather than the straight-flute taps you have there.

ChrisH

Thanks for the advice Chris. Probably some lubricant might help in hindsight too