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A bowden geared extruder for Rostock - based on Gregs

by RichRap, published

A bowden geared extruder for Rostock - based on Gregs by RichRap Mar 11, 2013

Description

This is a geared extruder for Rostock and other printers, it uses 1.75mm filament and 4mm Pneumatic fittings for PTFE tubes as the Bowden element.

Recent Comments

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Ahem -- please to scuz - but the zip that D/Ls for the "Download All Files" does NOT contain the files in the "Thing Files" listing. I tried twice, but all I see therein is the guidler STL. Sorry?
What kind of bolt do you use to mount the bearing in the pressure block? On the Airtripper Bowden extruder the axle get printed out, is this different?
You forgot to add bearings to your BOM

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Instructions

Print out and assemble with Herringbone gears (any to fit Greg's design) and use the 1.75mm filament guide here.

Flip the design if you want it mounted the other way around or if you are planning a dual bowden extruder setup.

I have been running it for about 4 months, works really well - and can mount to t-slot frames if you like.

Sketchup file added so remix it if you like.

BOM as requested -

It's very similar to any of the other Greg's / Wade's Extruders on Thingiverse -
To print the 1.75mm Version -

So you need to print the two models here.

And a set of Gears - I recomend using the Parametric Herringbone Gear Set for Greg's Accessible Wades - by Triffid Hunter - thing:10707

The hobbed bolt is a standard 8MM type, it should be the most common available from many places - check eBay.

Some long M3 screws for the pressure block springs (about 55mm long)

1 x 35/40mm M3 screw for the pressure block.

Two springs or silicone pads.

3/8" or 10mm Pneumatic fitting to accept 4MM PTFE Tube.

A length of PTFE tube 4mm OD 2mm ID

4 x M3 x 10mm bolts for the motors and small gear

M3 nuts x 5

M8 washers - to space the hobbed bolt correctly

M8 Locknut

I think that's it?

Or use the Version by Woodsmoke if you use 3mm Filament.
Ahem -- please to scuz - but the zip that D/Ls for the "Download All Files" does NOT contain the files in the "Thing Files" listing. I tried twice, but all I see therein is the guidler STL. Sorry?
What kind of bolt do you use to mount the bearing in the pressure block? On the Airtripper Bowden extruder the axle get printed out, is this different?
You forgot to add bearings to your BOM
Really appreciate all the info you share. I'm building my first Delta, and am going with your extruder here, and your spectra pulley designs. I can't wait to try dying the Nylon filament:-)
What kind of Pneumatic fitting do we need I'm not sure what to search for
It's a 1/8" BSP or BSPT push fit Pneumatic connector, you can get them in all plastic (delrin) or metal.
So if I search those terms on ebay I should be able to find what I need?

Another question:
the bearing in the pressure block what is used for the axel, 8mm rod? Forgive me this is my first RepRap (Rostock) and I havent had to build a Wades/Gregs based extruder, I've only used various mendle printers.
You got it - or you can get 10 of them from Hong kong for about $6 - search - 10 x Straight Quick Connectors Pneumatic Fittings 4mm x 1/8" PT Male Thread

Yes, 20mm x 800 smooth bar or threaded rod for the idler bearing.
(1) Downloaded both parts.
(2) Sliced in Slic3r 0.9.9.
(3) Printed in 3 hours with .85 infill.
(4) Knocked off support box.
(5) Perfect fit! Thanks!
Andrew (http://3dhacker.com)
Hi RichRap, Is it stil the best Extruder to your taste? I am Building my first printer and I will have those print hopefully at work ;o)
Yes it is, I still prefer a geared design, and herringbone printed gears.
I'm very happy with this for direct or Bowden configuration - Good luck with the first Printer build.
Thank you, thats the part I was looking for in Solidworks, but you post it as Sketchup So i will try from there. I have a diferent Motor so I need to Modify the hole for the base. Thanks'
For the herringbone gears can you just use the straight stl files off of Triffid Hunter's thing or are you meant to generate your own? I dont know anything about script's so im not sure how i would go with trying to generate my own gears.
Yes I use them directly, or you can use any others that are designed for Greg's extruder
just a quick question, the block of material under the section where the two parts of the extruder join, is that just support to be broken away?
Yes, just snap it off and clean it up, it's just to allow the idler lever hinge to be printed without using support material.
nevermind i got it
What size bearing is used for the idler?
The same sized used on the Extruder! - 608
Can I get a bill of materials ? What hobbed bolt does this use?
It's very similar to any of the other Greg's / Wade's Extruders on Thingiverse -
To print the 1.75mm Version -

So you need to print the two models here.

And a set of Gears - I recomend using the Parametric Herringbone Gear Set for Greg's Accessible Wades - by Triffid Hunter - thing:10707

The hobbed bolt is a standard 8MM type, it should be the most common available from many places - check eBay.

Some long M3 screws for the pressure block springs (about 55mm long)

1 x 35/40mm M3 screw for the pressure block.

Two springs or silicone pads.

3/8" or 10mm Pneumatic fitting to accept 4MM PTFE Tube.

A length of PTFE tube 4mm OD 2mm ID

4 x M3 x 10mm bolts for the motors and small gear

M3 nuts x 5

M8 washers - to space the hobbed bolt correctly

M8 Locknut

I think that's it?

Or use the Version by Woodsmoke if you use 3mm Filament.
I printed your nifty bowden set Rich. I have some of these push fittings on hand from when you recommended them to me a while back ;)

Did you manage to tap the hole in the extruder body for the fitting?
The hole is slightly undersized for the pneumatic fitting, all you need to do is use a hair-drier or heatgun and heat the hole - Just a little - then screw it in, gently, wait until it's cold and it will form it's own very strong thread, you should be able to remove and refit many times - not that you should need to remove the fitting as the tubes can be released by pushing the blue ring.

You may need to adjust the hole size depending on the size of thread on the fitting, they usually come in bonkers non metric sizes. I think the ones I have at the moment are 3/8 of a furlong in size!
Also, what inner diameter PtFE do you use for 1.75mm filament? What inner diameter PTFE would you recommend for 3mm? Basically, how much wiggle room should I have?
I always use 4mm Outer 2mm Inner PTFE tube for 1.75mm filament - works really well.

I would not dream of using 3mm filament in a bowden setup, but other people do, and you can get 5mm tube with 3mm inner, but I expect you should use 6mm with 4mm inner.
I imagine a 3mm filament would have exponentially higher friction. So I believe my hobbed bolt and j-end will accept a 1.75mm filament as well. Aside from the reduced friction, is there any other benefit to 1.75mm? possibly less filament contamination?
FYI people are using 1/8" ID ptfe tubing for 3mm filament. (3.175mm ID)

Why would it have more friction?
Do these kind of extruders generate enough pressure to drive the filament into the hot end? I find my J-End requiring maybe 4-5lb of pressure for good flow. Is there cause for worry with the PTFE tube? Also, how tightly and how is it affixed on the extruder end? Thanks very much.
These geared extruders can drive with a massive amount of pressure, much more than a direct driven type like the MK7

The reason I use Pneumatic fittings is that with almost all other clamp methods they will work loose or damage the PTFE tube.

They hold the tube really well, with a NEMA17 motor if you don't set the current correctly the extruder can pull so hard it will break the filament in a spool tangle.

The other end (Hot-end) is here - thingiverse.com/thing:60539
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