Dec 2017 All updated to a version I have saved as "V22".
Step and Iges files available at Grabcad (https://grabcad.com/library/dag-geared-belt-extruder-1)
3mm Pneumatic fitting, M5 (for outlet)
3mm id 7mm od 3mm thick ball races (four needed, fitted inside the 13 T gear/belt pulley)
(this is almost certainly overkill, and 2 would do, but they are cheap and fitting 4 is easier than trying to hold two in the correct places)
608zz ballraces (8mm id, 22mm od, 7mm thick) "skateboard ballrace", three required.
8mm *60mm bolt and nuts for main drive (you may also need washers to help this fit "nicely")
M3 bolts : 8mm (three for holding the motor)
20mm two for the casette
30mm, three needed, two for the outlet, one to hold the casette in the main bodies.
35 to 40mm for the tensioning screw (you may be able to use a 30mm)
M3 brass press in inserts (4mm dia) five needed
M3 grub screws or short 8mm bolts and nuts for the Herringbone gear version.
One M3 nut for the tensioning screw (or use a brass insert)
M5 30mm bolt and nut for 20T idler pulley
20Tooth 8mm Drive Pulley with grub screws to hold to 8mm shaft (for main drive )
20Tooth 5mm hole 9 mm thick Idler Pulley (I used a version with bearings)
(or use a standard 20Tooth 5mm hole "Drive Pulley" and the alternate Motor bodyside STL)
If using the Belt drive and not the herringbone drives you will need:
20T GT2 5mm hole Drive Pulley
60T GT2 8mm hole Drive Pulley (or print one of you are adventurous)
200mm GT2 belt (same as the main traction belt)
This was designed to be used with delta printers, with the outlet fitted to 20x20 framework at the top of the printer. The outlet can be fitted to the printer first, and then the main extruder "slots" onto the outlet, and is held by two M3 bolts. This makes it easy to remove for adjustment/servicing.
Oct 2017 Slightly revised outlets and drive gears.
The 41 tooth gear now has a very slightly smaller "belt" drive diameter compared to the originally published version. This reduces "slip" between the 13:41 gear ratio and the belt movement on the two parts.
The outlet path has also been revised to better match the actual filament path as it exits the drive. This results in a filament path 5 degree off from the "as designed" path, and allows less lateral movement of the filament in the extruder, preventing the filament from bending under more extreme loads.
4 Aug 2017 NOW updated with Large Herringbone gears..Made using
Video of updated version added. Initial tests show it is capable of pushing filament at about 2.5 to 3kgf before the torque of the motor is overcome.
Note it is "upside down" in the STL full model....The filament comes OUT of the connector shown on the top in the model. The "Belt" and "Filament" in the drawings are only approximate, but show their general positions.
Experimental belt extruder
Design started as a version of the gunstruder. with elements of Vaeder.
The main v drive is geared to one of the 20T GT2 pulleys. This dramatically improves the drive. (like the librostruder and vaeder).
I have used pulleys that can be purchased easily on ebay or similar.
I have tested this with my force filament sensor (https://www.thingiverse.com/thing:2429390) and in the video cut I pan to the screen displaying the force applied. This is about the same or more force than I can get from a Wade extruder before it strips the filament. The advantage of the GBE extruder is that it does not damage the filament. Once the filament pressure reduces (by extruding ) the filament is again driven at full force. This is in sharp contrast to a wade or similar, where once the filament strips, it can only drive at about 0.5kgf if that.
I think it could be improved by changing from the belt gearing to the herringbone gearing as used in some wades, this should increase the torque on the filament further for a given motor.
You should not need supports, but parts will need to be rotated to place their flat surfaces "down".
The tension parts are at some funny angles so need care to place "flat".
I printed with a 0.4mm nozzle, 0.2mm layers.
I have versions in both ABS and PLA.
Open all holes to 3mm or 5mm as required. In all cases you can use longer screws, and this may assist assembly.
Once you have assembled the cassette of the main printed gears, it is a good idea to run them in and make sure they are free to move. Some filing of the gears may be necessary at this point....The bearings should be fitted in the pulleys so that the pulleys do not scrape on the insides of the cassette body.
Bearings are 608 roller skate types. and 3mm7mm3mm small bearings for the printed GT2/gear pulley. You can use two bearings in this pulley plus a spacer, but it can also take 4 bearings, which can be easier if the spacer is hard to make.
Images below show the belt driven version, but the Herringbone gear version is exactly the same, .... just with Herringbone gears!.
This was the original with belt gears,Note that the bolts in the min body have now been rotated by 180. This makes them easier to remove once the herringbone gear is in place.The herringbone gear version increases the force available to the extruder.
New version uses two 20mm M3 bolts
Note: New version has the bolts reversed for easier access with the herringbone gear.