[Mendel] Almost There! Help with calibration?

Hello fellow reprapers!!!

It's been a while since my last post (and try) to make/finish my Mendel.
Two years ago I started on trying building one (ForumTopic) and now finally I made it!

Some info for my Mendel
Firmware: Klimentkip (115200 Baud)
Electronics: Arduino Mega 2560 + RAMPS 1.3v + 3 x Pololu A4983 stepper driver + 1 x Stepstick A4983
Extruder: Wade's Geared Extruder (reprap.org/wiki/Wade's_Geared_Extruder)
Extruding Material: 3mm ABS Natural
PC Software: ReplicatorG 34 for 5D (from here[code.google.com])

Here you can see some attempts of my Mendel...
[www.flickr.com]
As you see I think there is some problem with my Mendel or it needs some type of calibration...
Usually it starts by printing a raft, then printing the object, but after a couple of layers it seems like the extruder is not extruding anything. I've made some marks on the ABS to check how fast the extruder is taking it in and it seems that it stops...
Maybe when the extruder's motor goes the other way to stop the tip of leaking plastic, the hobbed bolt "eats" the ABS and it can't be pushed again out to the nozzle...

I know that with ABS I should have a heated bead but for know I'll have to live without it

Please, any reply is valuable!

Regards from Greece.

Is the hotend still at the proper temperature when it stops extruding?
Did the hobbed bolt eat into the filament (stripping it)?

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Hey there!

The hotend is at the proper temperature when the extruder stops extruding abs.
The hobbed bolt kind of eat in to the filament (photo) but that small bits (here) look suspicious...

Yes, it did strip the filament.
Since you say the temperature of the hotend is correct then you either have squeezed the filament too tight or the nozzle is blocked with something.
How about a picture of your hotend.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Here are some pictures of my hotend. I removed the whole extruder so it's more clear if there is something wrong... (pics)

I did an experiment and tried to print a pulley. Whenever the extruder seemed blocked I paused the print, removed the part and resume the job. Then magically the extruder was ok. So probably the tip was blocked because the z axis isn't elevating enough after printing each layer?

Thanks for the replies :-)

Edited 1 time(s). Last edit at 08/21/2012 04:04PM by stam.

That sounds reasonable, then verify that you aren't loosing any steps and that the Z-axis is properly calibrated.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Hello my friends!!

I flashed the latest sprinter firmware on my mendel, and I changed the axis step unit line to:
#define _AXIS_STEP_PER_UNIT {80, 80, 6720 ,700}
and now each axis actually move for the mm it's supposed to move!

Here is the first print and the second!!!
There was a drama with the cube but it was my fault...

My problems now are obviously as you see the wrapping (due to no heatbed I have troubles with the ABS sticking to the Kapton tape...) and the infill maybe...

I think I might try buying some PLA instead of buying a heatbed...

A really happy repraper!!!!

i have not yet made my printer ... it looks like the output is sometimes thin and sometimes thick ... is the extrusion smooth or temp slightly too low? and it looks like it is extruding too much as stuff starts to bunch up or something like that ... (trying hard to think like the behavior of plastic) ... or isit normal that ABS does that whenever there is no adhesion t bed ?

The extrusion is pretty smooth

My problem is that the plastic sticks really hard to the bed (kapton tape) and most of the times it fails...

I've just ordered a heated bed and a thermistor, so with a little bit of luck, after a couple of days I'll be ready to print!!!

Hello there!!

Just received my heated bed and tried to print the classic wade's gear! As you see here it's quite decent but I still have to buy a glass to put on top of the bed and calibrate better the z axis...

Thanks again for all the help!!!