In case you ever wondered what to get for your money, I get you covered 
From left to right:
- 0,40€ MK8 pulley
- 12€ Hobb-Goblin Pulley
- E3D Titan (60€ complete with extruder body)
Hey, weren’t you the one recommending the Chinese MK8s to me? The ones i got look exactly the same (completely dull), they do work for super-careful extruderation, but obviously are useless when it come to faster printing or tougher materials.
For this, I just took pictures and didn’t compare their functionality. Despite having six cheap MK8 Pulleys flawlessly working in my printers (and in my DICE!).
Ive got that mk8 (since a few weeks on a geared nema) and its the best i had so far. Damn wade has a too small diameter 
I’m a big fan of the hardened 8mm bore drive gears http://tridprinting.com sells. Very grippy and high quality.
I really haven’t had any issues with the Chinese MK7 and 8 gears. I do like my printrbots one better but it cuts into the filament quite a bit
http://www.robotdigg.com/product/73/RobotDigg-Filament-Drive-Gear try it never return back…
@Ryan_Carlyle that look slot like the old TrinityLabs drive gear which was one of my favorites. Only downside is the deep and wide relief profile is best suited for 3mm filament.
@Eclsnowman it works great for 1.75mm. Frankly, from a grip performance standpoint, we should all be using flat teeth (no groove, straight cut across) with grooved idlers. A tight-fitting groove chews up the filament as it turns because of the radius variation, and ends up having worse grip than a sharp flat tooth. The tridprinting version, new E3D profile, and the tatsu are all just about the closest to straight teeth you can get without requiring a grooved idler for centralization.
@Ryan_Carlyle I see what you are saying about the tight groove radius having issues at the tips as it goes through the arc while gripping. It’s just that in practice on the test rig I have seen different results than theory. I was testing for filament deformation and grinding during cycle testing (feed/retract 200mm of filament hundreds of times while carrying a 5lbs load) as well as max pull before failure. To me it showed better force and less slip with a gear cut like the Bondtech than with standard MK* or even the more square Trinity Labs style pulleys. Granted the dual grip of Martin’s design does sway the results. Most other gears failed the cycle test under load. They would never feed (lifting the weight) as much as it would retract (lower weight back down). So it showed the slip that occured and eventually the weight was banging on the ground.
Here was the rig running before MRRF: https://goo.gl/photos/CZSvHbEFVqdA1m1a7
@Eclsnowman the Bondtech is great because it’s a fixed-width dual hob. It has very little to do with the specific tooth shape in that case. The filament can’t slip without entirely shearing at the wide base of the “thread” cut into the filament by the drive gear teeth. In comparison, every sprung idler and single hob design in the world can slip by jumping the hob teeth, which typically causes immediate damage to the filament.
Shear distortion, the main cause of lost motion under load, is also minimized by the dual hob. Two gears means you’re very evenly pushing on most of the filament cross section, versus a single gear that has to apply a large shearing force to one side of the filament.
Dual hob designs pretty much have to have some curvature to centralize the filament. But ignoring that issue, a straight-tooth dual hob design would perform extremely well.
There has been lots of testing over the years of hob shapes. Groove curvature of similar radius to the filament performs quite poorly. Less curvature is generally better. Look at the Titan drive gear vs the Hob Goblin. E3D did loads of testing to arrive at the new nearly-straight tooth geometry.
The FB2020s run HobbGoblins combined with the Schlotzz extruder they’ll feed at about 35-40mm/s and retract at 100mm/s, They’re evil little drive gears…