Yes indeed !
Here is a little video showing it in action : <link to video todo>

Let's print a small object and see how it's going on.
During the mounting of my counter to the extruder head, I unfortunately broke the part that hold the conduit and guide the filament just before it enters the extruder mechanism. So I have to print myself a new one.
That part is not too big so it will be a good candidate for this test... plus I need it !

Here it is in SU :

And here it is printed and mounted :


And what about my counter ?
Well it just exploded !
Not physically, no ! it works fine. It's just that it turns quite fast so that even for a relatively small object like this one it went over its 3 digits capacity, ending at (1)089.

Let's write this value done. But it means nothing until we can do a counter/extruded filament lenght comparison.
In other words, which lenght of filament is 1089 ?
I new I would need that information so I had previously placed a small piece of duck tape at the end of my first filament guide.
So that I can tell that about 67cm of 3mm diameter filament have been extruded.

Now it's only a matter of simple math...

If 67 cm of filament is 1089 on the counter, how much the counter should display if I extrude 10 cm ?
1089 / 67 * 10 = 162
I will need to check that... (no ! not that operation result... but if 10cm extruded will display 162) 

Another way of doing it with more "complex" math".
Let's say I forgot to put a piece of duck tape (or any other mark) on the filament before to print.
I can allways measure the weight of the finished print (includind raft and supports) and find out how long filament this is.
But with this method you'd better have very precise scales in the low range (from 0 to 100g for ex.).
The relation between grams and centimeters would be :

W = πr^2 * L * 1.05 or L = W / (1.05 * πr^2)

  • W = weight of the final object (in g)
  • π = 3.1415927
  • r = 1.5mm (3mm diameter filament / 2)
  • L = length of extruded filament (in mm)
  • 1.05 is the average mass density of ABS in g/cm3

Which means that with 67cm extruded, the above object should weight 7.42g.
My kitchen scales display hesitates between 7 and 8. Not bad !

Conclusion :

I still have to compare these values with the Skeinforge - Statistics results.
I don't think I will keep the counter mounted definitively but it's a good measuring instrument that was fun to do !
If I do I will have to find another counter with more digits to do measurements on big objects.
But it's just a "funny" gadget...

All this "simple" math has given me a real headache ! Not you ?
I guess I deserve a little pause now...