Nearly There!

Hello everyone
I am nearly there but not quite and need some help to push me over the line.

My setup is Sprinter firmware, RAMPS1.2 and ReplicatorG software.

Earlier in the week, when I didn't have the extruder, I was able to attach a pen and draw the 20mm calibration box and even write my name.

Today I received my hotend and some PLA and connected everything up.

I recompiled with the correct thermistor and reloaded the firmware.

In ReplicatorG with Klimerklip selected I am able move all the 3 axis and also get the extruder motor to move.

But, when I try to print the 20mm box I do not get any movement on any of the motors.

So close but yet so far!
Any ideas would be appreciated.

regards
Mark

and just to add a bit more information the printer motors move correctly when I disconnect the thermistor.

is the hot end getting up to temperature properly when you begin the print?

Check for a short between the thermistor and the heater.

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Thanks gents,
The thermistor seems to work as I can see a nice exponential curve as it reaches the set temperature in the control panel mode. And does extrude a nice thin stream of PLA.

But regarding it reaching the right temperature when I am trying to do an actual print is a good point. Where do I set this?

you will set the print temperature in slic3r or skeinforge, then you can change it through the interface realtime as the print progresses. the slic3r/skeinforge setting just sets the temperature initially, after that you can change with the interface.

i am not familiar with replicatorg, but i know this is how it works with pronterface. i had a similar issue on marlin firmware when i first set up my machine, turned out to be that the "extruder minimum temperature" setting was too high for printing pla (195c). it would send "cold extrusion prevented" errors over the serial and not extrude anything. if the thermistor isn't reading properly (reading low) the system will never know it has reached the correct temperature, and the print will not proceed after homing. can you confirm that the thermistor readings are correct and showing (in the interface) the temperature as being above a reasonable minimum?

it definitely sounds like something with the firmware pausing to wait for the temperature control. try removing the filament from the extruder and then manually removing the temperature setting line from the beginning of your gcode (should be near the initial homing line). if the bot runs through the motions with no problems after that you will know it has something to do with the hotend/thermistor not reporting or heating up properly.

I would go with something other than RepG, although I can see why someone would find it attractive. I went a few rounds with it before settling on RepSnapper, which I swear by, although I do not use the built in slicing function. For that, I use Skeiforge 0.41.

Thanks all for the advice. I am slowly (very) getting there.

I took the advice above and moved away from RepG and am now using Pronterface and seem to be getting somewhere. I can get the printer to map out the 20mm box and the extruder spills out a stream of PLA that seems to ball up around the print head. Maybe that is because I am not printing on to a surface but have the head 5 cm or so from the print bed. Would this seem a reasonable assumption?
Which leads me on to another question, how do I set the height of the end of the hot end to the print surface? Is this controlled by the z axis end stop? Which seems unlikely to me.
I have had a good search around for threads with ' initial calibrations' but can't seem to find detail here.
Sorry to be a pain but any ideas please?
Cheers
Mark

MarkMills Wrote:
-------------------------------------------------------
I can get the printer to map
> out the 20mm box and the extruder spills out a
> stream of PLA that seems to ball up around the
> print head. Maybe that is because I am not
> printing on to a surface but have the head 5 cm or
> so from the print bed. Would this seem a
> reasonable assumption?

This is a resonable assumption.

> Which leads me on to another question, how do I
> set the height of the end of the hot end to the
> print surface? Is this controlled by the z axis
> end stop?

Yes, it is. The endstop is to tell it where the bottom is and not to go any lower.
What I like to do (note that this is only my opinion not the only way to do it) is get the print head close to the bed, perhaps 1cm.
Move the z-endstop of close to where it would be triggered.
Tell the head to go down a small amount - 1mm at a time until it either triggers the stop or would be too close if you moved it again.
Move the endstop up or down as needed.
Keep repeating until you get the head to stop almost on the bed. Some say about a paper's thickness above the bed. I like to go just a bit higher.

You also need to get the bed level, so it has the same clearance from the extruder tip all over..
You're talking a clearance in the range 0.1 - 0.2 mm, so the final adjustment is pretty fine.

It also depends on how your bed is mounted - often an upper plate with screws holding it to the lower bearing-mounted plate with springs between.
The approach I use for initial setup is to wind the upper plate down a bit (1mm or so) so I'm confident the tip won't crash , roughly adjust the Z-stop to give Z-home within a millimeter of the bed,
then gradually adjust the bed screws up to get the fine clearance, gradually taking the extruder tip round the square, and rotating round the bed screw adjustments .
The good old "paper feeler guage" is not too bad a guide to 0.1mm per thickness - I actually adjust so "2 thickness gets under, 3 does not", to get roughly 0.2mm clearance, printing at layer height 0.3mm. If I go any lower clearance, the bottom layer gets sufficiently "smooshed" onto the blue tape (cold bed) that I need a chisel to get the object off after. When I get it just right, it takes a light "dig" under one corner to start breaking it away.
That will vary depending on your particular setup.

(another tip, before adjusting clearances, I raise the extruder 1 or 2 cm, heat the hot-end, then turn the heat off - and continually clean the tip of any ooze over the minute or so it takes to cool. If the tip is hot when trying to measure clearance, your feeler guauge may stick to it, and if any residual plastic hardens into a little blob and you take it to Z-home, there may be a micro-incident when the extra millimeter of plastic arrives at the bed before the tip does.

Great advice gentlemen. Thank you. I will give it a go tonight.
Cheers
Mark