Prusa i3 3D printer

[Gina]

I have my RAMPS cooling fan slowed down using a series resistor but I'm using 12v Nema 17 stepper motors and can use a much lower current.  In fact i'm not sure a fan is needed at all but it gives a nice feeling of safety

[tekkydave]

Now that I have everything in the control box set up and calibrated I have moved it to it's new home which is behind the printer next to the ATX PSU.

This also moves it another metre or so away from my desk so a little less noise when printing.

[Gina]

Good to have all the bits close to each other

I see you have a glass print bed and I gather you use PLA - do you find it sticks alright to glass?

[tekkydave]

It sticks fine so long as the glass mirror is clean and heated to at least 60C. I use 75C just to be on the safe side. Let it cool before trying to remove them.

[Gina]

Much like ABS then except a lower temperature.  I'll try it on my Large printer.

[mapstar]

It's quite a project you've got Dave and I know from my own how things get thought about then Re thought so to say.

Will you eventually be building it all into one unit or are you going to leave all the components free standing?

Also have you any ideas on what you will be printing? I'm not familiar with printed items but love a good project. Are they brittle sometimes? Or does it just depend on the plastic type used?

Damian

[tekkydave]

So far I have only printed in PLA which doesn't smell much so no problem with it all being open. If you search back in the topic you will see I posted some pics of a mini-greenhouse cover I am planning to turn into a sealed cover to use when I try printing in ABS which does smell a lot. I am hoping to fit an extraction pipe to vent the fumes outside. This will pack away when not in use.

PLA is hard but also can be brittle and wont take much abuse whereas ABS is softer but more robust (Lego bricks are ABS!). There are other plastics e.g. Nylon, PVA etc

I don't have plans to print anything in particular, just anything I need at the time. I built the printer for it's own sake really and the kits are relatively cheap now - mine was £399 + £12 p&p.

[tekkydave]

Just ordered one of these to have a go at auto-bed levelling http://m.ebay.co.uk/itm/221863869845?_mwBanner=1 using the instructions here http://www.instructables.com/id/Enable-Auto-Leveling-for-your-3D-Printer-Marlin-Fi/

[Gina]

I'm hoping to have mine working tomorrow   But I'm just using a microswitch type standard endstop.

[tekkydave]

I was thinking of using a microswitch but I like the idea of the proximity sensor. It has a range of 4mm so you can set it 3mm above the nozzle level and not have to move it in/out of position.

[tekkydave]

The dial gauge I ordered has arrived.

[tekkydave]

More goodies arrived in the post - the proximity sensor.

[tekkydave]

Did a quick test of the sensor. Connected up to 12V supply and measured the output. When a metal object is brought close to the end the LED comes on and the output rises to 12V. A simple voltage divider made from a 10K and 15K resistor brings it down to 4.8V so it can be connected to the RAMPS.

Testing with a craft knife:

With a small spanner the gap is about 3 to 4mm.

I will need to put some small squares of foil tape on the bed at the points I will be measuring the height.

[mapstar]

Looks good Dave

As a rough guide the range of a proxy is about half the diameter of the face.

Damian

[tekkydave]

In my lunch break at work today I designed a bracket to attach the proximity sensor to the end of my existing extruder.

This is the correct orientation. It will slide over the free end of the extruder base and attach with an M4 bolt.

Other views:

I may redesign the extruder at some point and make this part of the main body but thats a job for the future.

[tekkydave]

I had trouble printing the bracket yesterday. It kept un-sticking from the bed which I have never had problems with before. I redesigned it slightly with more surface area in contact and fewer holes but still un-sticking. I got about two-thirds of a print which was good enough for testing with. When I attached it to the extruder though I realised my mistake. The sensor was too far in the negative Y direction so would be off the front of the bed when the X & Y axes were homed. This would mean it would be unable to home the Z axis. I have started redesigning a new bracket so the sensor is level with the extruder tip in the Y direction so is over the bed when X & Y are homed. I also realised the metal foil I had did not trigger it. Not enough metal in it. It can be triggered by the bed itself but needs to be mighty close as the glass is in the way. I have ordered a capacitative sensor as that will work with any material and up to 10mm from the mirror.

I'm a bit 'jet-lagged' today as I was up till 3am fixing a database problem for my employer. I'll post some piccies this evening when I am back at home.

[Gina]

A capacitive probe sounds interesting - any details please?   Hope you get over your "jet Lag" soon

[tekkydave]

This is the sensor http://www.ebay.co.uk/itm/171904921893?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[Gina]

Cheers Dave   Rather a long delivery time though - think I'll stick with servo motor and microswitch

[tekkydave]

The promised piccies.

This is the first failed print of the sensor bracket. I removed the curves and holes and tried again

The final attempt. Failed about 2/3 of the way through but cleaned up and sensor installed

Attached to the extruder

A sketched circuit diagram showing the 12V supply and resistor divider dropping the 12V output to 4.8V

Temporary connections using chocolate-block terminals. If I stick with the sensor, or the capacitive version I have on order I will put the components in the control box in a more permanent fashion.

[tekkydave]

I have ordered some servos and micro-switches in case the proximity sensor idea doesn't work out.

[Gina]

Good thinking

[mapstar]

Nice work Dave

[tekkydave]

I'm currently printing a new bracket for the proximity sensor as the last one wasn't very well thought out. I’m making the hole 18mm in readiness for the capacitive sensor.

[Gina]

I'm having to make a new bracket for my Z drive on the Pilot/Experimental printer.  There was a fault in the print at that's why it wasn't as stiff as expected.