Hello from New Zealand

[Apollyon25]

Hi everyone,

My name is Jared, and I'm a senior electronics engineer for a company that makes touchscreens for many of the worlds PC manufacturers.

Recently though I have been building my first 3D printer - A Rostock Mini.
It has provided a welcome distraction from work!

Very quickly, its a standard Rostock Mini with some of the modifications listed here: http://www.thingiverse.com/thing:51288
Most of the parts were sourced from either http://www.makershop.co.nz (Mike is awesome to deal with!) or http://www.geeetech.com.

Some hard fought lessons -
I tried an EZ-struder, but with 3mm filament, and near 1m of PFA Bowden tubing it would always slip. Or the driver would overheat and thermally shutdown/current limit.
I'm now using a 5.18:1 planetary motor - no issues at all.
I also tried a http://www.geeetech.com "J-Head", it probably contributed to the extrusion issues. Now using a http://www.hotends.com one.
Until recently I couldn't get KISSlicer to behave - it would print at top travel and try to lift beyond the end-stops, or it would try to print at glass level or below (i.e. through it)
Was using Slic3r however its slicing and print quality isn't as good - finally managed to get KISSlicer to work!
Thanks to all those who contributed .ini files - they have helped immensely!

Megatronics v2.0 hardware running Johan's Marlin delta/Kossell fork FW. Smart LCD controller and adapter... All pretty standard stuff and no issues with any of these.

A couple of minor tweaks that I have made are around the heated bed -
Micrometer 3-point bed leveling
Custom aluminium-clad PCB heated bed
Magnetically attached

I have seen a few posts on the setup (in FW with dimensions) particularly around the build plane 'dishing'.
Many of the answers are piece-meal and incomplete/simply do not work, and I have not found an online answer to this.

So, my first forum contribution is to answer this.

0) home the machine (obviously implies you have end-stops correctly positioned, wired, maximum height set in FW etc)
1) setup in Pronterface three reference positions - one just in front of each tower, 10mm higher than the build surface.
2) setup a centre reference position, again, 10mm higher than the build surface.
3) move to each of the tower positions, one at a time, and step closer to the bed incrementally (via Pronterface)
4) use a piece of paper as a feeler gauge to be 'grabbed' by the nozzle
5) query the position of the head once the paper has been grabbed. Note the distance down.
6) adjust end-stop screw by the difference (noted) from zero.
7) repeat for the other 2 towers.
8) move the nozzle to the centre reference position and incrementally step down until you grab the paper, note the offset from zero here too.
9) in the FW modify the (I used Marlin) DELTA radius equation by adding a " - Delta_Fudge" subtracted variable. create a #define Delta_Fudge and set it to 5 to start.
10) compile upload and repeat 3-5.
11) I cannot remember which direction increasing this subtracted variable moves things but you'll figure it out!
12) repeat the moves to each of the towers and when the reported position (at which it grabs the paper) is the same as what you got for the centre, the bed "dishing" is now solved.

Altering the Delta Radius (by manipulating this fudge value) flattens the outer edges - the centre will stay at a fixed position.
This is what I never found out on the forums... it doesn't lift/lower the centre, it lifts/lowers the outer points.
Was definitely a "DOH!" moment.

That will do for my first post.
I'll post up some pictures of my printer and its prints when I remember my camera.

Regards,
Jared

[mhackney]

Welcome aboard Jared! I'd love to see your 3 point leveling system. I've designed and built one for my Max but I haven't had the chance to tear the machine down to install it!

cheers,
Michael

[Apollyon25]

The micrometers are off some XYZ linear stages which we have a ton of after automating some jigs.

I drilled a (just) clearance hole in the base plate and a side locking screw (and clearance bore to get the M3 tap in) in the end of the plate, one on each of the three long sides of the Rostock Mini base platform.

I had to offset them to fit my aluminium PCB heat bed and clear the steppers and their mounts.

I've got a piece of PVC (I think) rubber sheet cut to fit that acts as a thermal break.

On the bottom of the PCB, you can see some blue ABS magnet holders, which are high-temp-tolerant glued to the PCB.
The magnets are neodymium and have a centre hole and this hole is countersunk. This and the minimal clearance on the blue ABS parts locate the micrometer shafts and prevent them from moving laterally.

I was expecting it to not work, but it works brilliantly!
Of course you only technically need 1 fixed and 2 moving points to level a plane but I am a sucker for symmetry.

If anyone would like a copy of the Altium (or any other format) source to make my PCB - send me a PM.

Jared

[mhackney]

Ok, now THAT's a leveling system! Well done!

[Apollyon25]

haha thanks!
I can set pretty much exactly the same amount of bite of the nozzle tip onto a slip of paper at each of the tower positions.
Worked as well as I'd hoped.

[Eaglezsoar]

Absolutely a brilliant leveling system! Does anyone know of an online source that has that type of micrometer for a reasonable price?

[Apollyon25]

You should be able to get them from any mechanical engineering type shops - I'm not familiar with who in the US, but McMaster-Carr (who I've seen mentioned frequently) probably have them.
Just looked, yes they stock them - Measuring and Inspection section - Micrometers - Starrett Micrometer heads.
Just looked again at the price… wow! not cheap.

I'll have a look round the office to see how many we have leftover.
Obviously the freight may be significant to the US for individual pieces, but if you want to arrange a group buy at your end…?