1

Topic: The drive?

So I understand that the drive is leaving shavings from the filament during printing that can cause the extruder to fail.

What I am wondering is what if the drive wheel were to have a rubber surface? 
Or is it more a matter of torque that only a metal wheel can exert?

I am an open book, write on my pages that I may learn the wisdom that you posses.

2

Re: The drive?

To retrofit the drive (if rubber works), lobstermen here in Maine use these rubber bands that are about 0.50 id (relaxed).  They are cheap to get a handful I could get them for free.
http://penobscotmarinemuseum.org/pbho-1/sites/default/files/collection/Lobster%20Claw%20Bands.jpg

Can some one tell me the OD of the drive wheel?

I am an open book, write on my pages that I may learn the wisdom that you posses.

3

Re: The drive?

The OD is 12.5mm.

I really don't think those will work. When shavings are made, it's because the steel teeth are pushing so hard the plastic is disintegrating. I don't think you can approach the same tangental force that steel teeth make on plastic using rubber.

Usually shredding occurs because something is wrong, like the nozzle is clogged or the filament is getting too warm while feeding.

4

Re: The drive?

I would think a clog would be that the nozzle cooled.  If it got too warm it should flow more easily.

I am an open book, write on my pages that I may learn the wisdom that you posses.

5

Re: The drive?

Downeasta wrote:

I would think a clog would be that the nozzle cooled.  If it got too warm it should flow more easily.

No, a clog from debris. The nozzle is 0.35mm in diameter. That's not much bigger than a human hair, so it doesn't take much of a particle to clog it.

6

Re: The drive?

The filament can get too warm where the gear is.  If that happens it can soften enough that it bends under the gear rather than push into the hot end.  That usually also means something is going wrong if it is getting that hard to push.  If the filament is getting a little harder to extrude, that can cause some plastic to get shaved off and stuck in the teeth, which then makes the problem worse.

7

Re: The drive?

Thankyou for your input Ian it makes alot of sense.

Does this mean that the drive is too close to the hot end?

I am an open book, write on my pages that I may learn the wisdom that you posses.

8 (edited by Downeasta 2013-06-18 08:04:57)

Re: The drive?

elmoret wrote:

No, a clog from debris. The nozzle is 0.35mm in diameter. That's not much bigger than a human hair, so it doesn't take much of a particle to clog it.

Actually?  A human hair is around 0.004" thick.  .35mm comes to around 0.0137" more than three hairs.  But I suppose I am splitting hairs now.
http://www.thetruckersreport.com/truckingindustryforum/images/smilies/roundies/biggrin_25523.gif

I am an open book, write on my pages that I may learn the wisdom that you posses.

9

Re: The drive?

Overheating of the filament near the drive is usually caused by heat from the extruder motor.  If you ever find the filament bending under the gear, it is often due to failure of the fan on the back of the motor.

10 (edited by adrian 2013-06-18 14:42:28)

Re: The drive?

Downeasta wrote:
elmoret wrote:

No, a clog from debris. The nozzle is 0.35mm in diameter. That's not much bigger than a human hair, so it doesn't take much of a particle to clog it.

Actually?  A human hair is around 0.004" thick.  .35mm comes to around 0.0137" more than three hairs.  But I suppose I am splitting hairs now.
http://www.thetruckersreport.com/truckingindustryforum/images/smilies/roundies/biggrin_25523.gif

I was going to give you kudos.. but then you ruined it by using Non-SI units.... And more so by 'converting' an SI unit in the same sentence... What is it with Burma, Liberia and the US insisting on having discussions in Non-SI Units... smile

And a human hair in research can be observed to range between 17 µm to 181 µm ... or 0.017mm to 0.181mm ... So only two human hairs if you've got thick hair wink

SI Units for the win... as used by 193 other nations in the world wink wink

11

Re: The drive?

I only think in 0.000" (+/- 0.0005) as I like to build things that have tolerances.

Sorry if you dont appreciate it.

I am an open book, write on my pages that I may learn the wisdom that you posses.

12 (edited by adrian 2013-06-18 14:52:25)

Re: The drive?

Downeasta wrote:

I only think in 0.000" (+/- 0.0005) as I like to build things that have tolerances.

Sorry if you dont appreciate it.

Yes, because you can't possibly design a tolerance with a mere Micron wink

Quick - Call the world wide scientific industry - Their measurements are out, particularly at the molecular level !!! smile

(I regularly do PCB design work.. I am *very* versed in Mils and live in the sub-20 mils zone. Doesn't mean its magically more accurate than a Base 10 derived international standard wink )

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Re: The drive?

5 ten thousandths isnt that bad for tolerances.  Heck some of my hydraulic motors are tighter than that as they are metal sealed by the fit.  Blowby occurs when it wears off one thousandth.

I am an open book, write on my pages that I may learn the wisdom that you posses.

14 (edited by adrian 2013-06-18 14:57:29)

Re: The drive?

Downeasta wrote:

5 ten thousandths isnt that bad for tolerances.  Heck some of my hydraulic motors are tighter than that as they are metal sealed by the fit.  Blowby occurs when it wears off one thousandth.

Yup, Interference Fits are fun... but doesn't mean using thousands of an inch makes it more accurate... thats all I'm saying.. there is nothing magical or special about a Mil vs a Micron - except one is an International Standard, understood and accepted and utilised all over the world, and the other is from a bygone era and is used formally in only 3 nations in the world.. Burma, Liberia and the US.

Not sure how that makes mils more accurate for tolerances than a micron (which is what you stated above....)