Where is a good place to get a direct drive extruder drive gear?

[Daniel Friesen]

 I finally got enough pieces to decide to unwrap my filament and try pushing it through my extruder. Unfortunately I've discovered that the cheap MK7 I used on my printer is practically worthless. The grip is so weak that they have practically no force on the filament.

I'm probably going to replace my drive gear with one from a better supplier.

Does anyone know of anyone that sells really good drive gears (pref MK7)?

[Derek P]

Does anyone know of a good test for extruders that would allow for comparison? I have some info that the Mk8 is 30% better than the MK7 but I'm not sure I believe it.

- Derek

[Nick Wimpney]

Which one is "better" will vary depending what you're using them with.  I don't remember where I saw it off hand, but I did see one that actually graphed holding force, etc.  IIRC, for most things the mk7 still had a slight edge over the MK8, but there were some exceptions.

What's wrong with the cheap one you have?  What hotend/plastic/temperature you running?

I bought some cheap stainless MK7s from dx, and they seem to be holding well (though I only tested by pulling the filament by hand.  Haven't hooked it up to a controller yet.)

--
You received this message because you are subscribed to the Google Groups "3D604" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3d604+un...@googlegroups.com.
To post to this group, send email to 3d...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/3d604/5eb051eb-b6b2-49bf-84b8-cb684b4070ec%40googlegroups.com.

For more options, visit https://groups.google.com/d/optout.

[Daniel Friesen]

On 2015-06-10 11:53 AM, Nick Wimpney wrote:
> Which one is "better" will vary depending what you're using them
> with. I don't remember where I saw it off hand, but I did see one
> that actually graphed holding force, etc. IIRC, for most things the
> mk7 still had a slight edge over the MK8, but there were some exceptions.

I read this one once:
http://airtripper.com/1676/3d-printer-extruder-filament-drive-gear-review-benchmark/

It does say good things about the MK8. However my direct drive extruder
is designed for the MK7. And the MK8 has a different diameter. So I
can't use the MK8 as then the path the filament would have to take would
no longer be straight.

> What's wrong with the cheap one you have? What
> hotend/plastic/temperature you running?

The teeth have practically no grip or bite into the filament to deliver
force from the extruder.

I've got a Wilson TS with the direct drive extruder made for it. The
filament is PLA I purchased from SMI "Premium" stuff from MG Chemicals.
Temperature is irrelevant, the fillament isn't even all the way down the
extruder, so the hotend isn't exerting any force back.
All the resistance comes from the stiff curved nature of the pla rubbing
up against the shaft down the extruder into the hotend.

I am aware that there are some things I could do to attempt to improve
the grip of the gear I have. I could swap out the light spring I have
for a heavier one so the bearing puts more force between the fillament
and the gear. And I could physically push the fillament deeper down the
channel so that the tip brushes against the PTFE tubing not the printed
parts of the extruder (then only the non-tip portions would have
friction against it).

But ultimately. If I screw the tensioner so that the light spring is
almost completely compressed. And the strength of the drive gear remains
unchanged and has no grip on the filament. Then, even if I use a heavier
spring and assist the extruder so that the driver gear just barely gets
enough force to print something, the drive gear itself is still going to
be so weak that if the extruder needs to deliver any extra force to the
filament at one point during the print, it's not going to deliver the
torque from the stepper motor when it's needed.

So I'd still like to replace my MK7 drive gear with a better constructed
one that has reasonably deep and sharp teeth.

~Daniel Friesen (Dantman, Nadir-Seen-Fire) [http://danielfriesen.name/]

[Daniel Friesen]

On 2015-06-10 12:53 PM, Daniel Friesen wrote:
> I am aware that there are some things I could do to attempt to improve
> the grip of the gear I have. I could swap out the light spring I have
> for a heavier one so the bearing puts more force between the fillament
> and the gear. And I could physically push the fillament deeper down
> the channel so that the tip brushes against the PTFE tubing not the
> printed parts of the extruder (then only the non-tip portions would
> have friction against it).

These tweaks did make a difference. Though my heavy spring is actually
too strong. I can barely pry the extruder open to put filament in.

So now I also need to find a local place I can find varying lengths and
strengths of springs to try out.

Maybe I should also find a longer screw.

[Nick Wimpney]

princess auto has big bags of assorted springs for cheap. I think they are only about $5. Mine has some nice stiff ones that seem reasonable for a single spring feeder.

--
You received this message because you are subscribed to the Google Groups "3D604" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 3d604+un...@googlegroups.com.
To post to this group, send email to 3d...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/3d604/557CCA3A.1000001%40gmail.com.

[Rob Hall]

I have some mk7 gears on the way they should be here soon

To view this discussion on the web visit https://groups.google.com/d/msgid/3d604/CA%2BmEz%2Bqo0XDpqiVZ9-Vddq9VQDr3AvaXK-%2BYKoj5%2BCnzaoYWWg%40mail.gmail.com.

[broncosis]

my gears came in should have posted sooner while they don't seem to bad I think I will try to run a tap on one and make them a bit sharper

On Monday, June 15, 2015 at 10:39:03 AM UTC-7, broncosis wrote:

I have some mk7 gears on the way they should be here soon

On Jun 13, 2015 8:12 PM, "Nick Wimpney" <nick.w...@gmail.com> wrote:

princess auto has big bags of assorted springs for cheap. I think they are only about $5. Mine has some nice stiff ones that seem reasonable for a single spring feeder.

On 13 Jun 2015 5:26 pm, "Daniel Friesen" <nadir.s...@gmail.com> wrote:

On 2015-06-10 12:53 PM, Daniel Friesen wrote:
> I am aware that there are some things I could do to attempt to improve
> the grip of the gear I have. I could swap out the light spring I have
> for a heavier one so the bearing puts more force between the fillament
> and the gear. And I could physically push the fillament deeper down
> the channel so that the tip brushes against the PTFE tubing not the
> printed parts of the extruder (then only the non-tip portions would
> have friction against it).
These tweaks did make a difference. Though my heavy spring is actually
too strong. I can barely pry the extruder open to put filament in.

So now I also need to find a local place I can find varying lengths and
strengths of springs to try out.

Maybe I should also find a longer screw.

~Daniel Friesen (Dantman, Nadir-Seen-Fire) [http://danielfriesen.name/]

--
You received this message because you are subscribed to the Google Groups "3D604" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3d604+unsubscribe@googlegroups.com.

To post to this group, send email to 3d...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/3d604/557CCA3A.1000001%40gmail.com.
For more options, visit https://groups.google.com/d/optout.

--
You received this message because you are subscribed to the Google Groups "3D604" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 3d604+unsubscribe@googlegroups.com.