Comments on: 3D Printer Surgery #4 Extruder Upgrade Part 3

By: Mark Heywood

Mark Heywood — Thu, 25 Oct 2012 19:50:10 +0000

I don’t have a MK7 drive gear type to see how much the filament bends round. However, I uploaded a modified version of the 3d printer extruder to give the filament an easier path around the larger extruder drive gears to reduce friction.

The larger 3d printer extruder drive gears will have a better grip on the filament because the filament slightly wraps round the gear. Having a straight path just makes it easier to feed new filament into the extruder.

As long as you’re using 1.75mm filament and and the filament is not the very brittle kind then your 3d printer extruder should work great.

All the best with your Rostock,

Mark

By: Steve

Steve — Wed, 24 Oct 2012 05:43:28 +0000

I noticed in one of your pictures that the Maritime drive gear allows the extruder to provide a straight path for the filament right through to the Bowden tube. I’ve assembled your extruder using a MK7 drive year. The MK7 gear forces the filament to bow somewhat around the drive gear. I have not fully assembled my Rostock yet so I’m uncertain if this will pose a problem. Any thoughts regarding this?

By: Mark Heywood

Mark Heywood — Tue, 16 Oct 2012 11:28:47 +0000

I can print a set of extruder parts.

I’ll get the 3D printer to print a full set of extruder parts in the next day or two, then I will contact you by email.
Most likely you will have to get the bearing, plain insert gear and tube yourself. The screws and the piece of Rubber Diesel Hose Tubing I’ll include.

Mark

By: Andrey

Andrey — Mon, 15 Oct 2012 11:54:44 +0000

Hi Mark,
I’m first time builder of RepRap machine and would like to buy your design extruder or just printed parts for it. Please, let me how it’s possible to do.
Regards
Andrey

By: Mark Heywood

Mark Heywood — Thu, 16 Aug 2012 18:50:37 +0000

I’m still using the plain insert gear at the moment because I’ve been able to get it to work due to the improvements I’ve made to the hot end. As long as the hot end can extrude PLA filament at a wide range of temperatures without jamming, then the plain insert can be made to work. For example, I’m using PLA that extrudes best at 220c and some PLA extudes best at 190c, and because I have active cold end cooling, there is no filament jamming or swelling before the melt chamber, even at higher temperatures.

I’ve not used ABS filament so I can’t advise on that in case that’s what you are using. If you have a hot end nozzle that works well with 1.75mm PLA then the plain insert is worth the try.

By: Brian

Brian — Mon, 13 Aug 2012 21:43:49 +0000

I followed your original BOM and am going to be using the 5mm plain insert [model boat gear] for the extruder. Have you had problems with filament stripping because of the fine teeth? I read somewhere you or ??? suggested a more aggressive tooth or to hob the gear? What is your status with this?

By: Mark Heywood

Mark Heywood — Sun, 08 Jul 2012 00:58:25 +0000

I’m using a hot end similar to the Mendal Parts V9 Hot End, the heat sink plate and fan are required to make it work with 1.7mm PLA when extruding at higher temperatures.
My extruder setup keeps the filament as cool and as stiff as possible until it reaches the melt chamber, this avoids jamming due to filament getting too warm at the cold end and buckling under extruder pushing force.
I have filament that needs around 220 degrees C to extrude and would not work with the sumpod extruders because the PTFE tube got too hot causing the filament to swell before it reached the melt chamber leading to jamming.

If you are using the sumpod nozzle with the peek insulator, I would recommend heat sinking the peek insulator to draw heat off to prevent the PTFE tube from getting too hot.

This is a youtube clip that shows a similar hot end that I’m using in detail: http://youtu.be/sR9l5O69MCM

Mark

By: William

William — Sat, 07 Jul 2012 12:53:29 +0000

Hi Mark,
I made the extruder and it works well.
But now I’m suffering from the dreaded PLA jamming, so I’m looking at the potential hot end problems. I notice you are using a different hot end. What is it and what are the advantages?
Regards
William

By: Mark Heywood

Mark Heywood — Thu, 07 Jun 2012 18:35:40 +0000

I think the 3d print works for me because the nozzle I’m using is pointed rather than flat like the original SUMPOD nozzle. You could use Skeinforge/Multiply to print two at once, making the nozzle change between the two after each layer, giving each layer time to cool before the nozzle returns to complete the next layer.

My SUMPOD firmware stepper calibration is:
DEFAULT_AXIS_STEPS_PER_UNIT {106.76, 106.76, 800, 67.16}
These are what I calibrated myself.

You could also increase the print speed by reducing the cool time, by half since printing two, so that the nozzle does not spend too much time over the print.

Printing the extruder parts do need a good set up to print well and different filament gives different results.

Mark

By: Rich

Rich — Thu, 07 Jun 2012 16:52:00 +0000

Hi – Did you have fan cooling when printing this? Every time I try to print the shaft, I get a mess of molten plastic. I’ve tried the 60s cooling, but because the head is still touching the plastic it keeps melting. If I enable orbit, there seems to be a bug where it releases control of the stepper and slips a few mm in the Y axis

Everything else has printed to some degree of success!

Rich.