Hobbed Extruder Bearing

A friend an I were putting together an extruder and a thought came through our heads. Why not hob a bearing for added traction? The bearing im referring to is the bearing in the extruder that pushes against the filiment for feed and retraction. Traction on both sides of the filiment surely would make some difference in the overall scheme of things. The hard part is trying to hobb a bearing. I've seen ones in the past that have a half circle like groove which help with alignment.

So I went about making a groove in a bearing as well as hobbing it. I used a customized bearing that my friend had made just for this part of the extruder. He had these bearings made with a lip on either side to sit perfectly in the door of the extruder so no piece of all thread is needed. I took some pictures but the camera on my tablet isn't the best. I will try and get better pics in the future. I have yet to try it out but I will update as soon as I do.

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How does it add traction unless it is driven?

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[www.hydraraptor.blogspot.com]

Its just an idea an experiment. The concept works in other applications with half of a feed system being un-driven. The un driven piece helps primarily with alignment. Most of the alignment would be from the groove in the bearing. Ive done some research and found similar concepts being applied. If you dont try something different then you will never know if it will work or lead to something else that will improve the process. Of course there is always the idea of it working or not but actually doing it sometimes leads to better things.

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I agree with nophead on this. The bearing isn't driven, so all you'd be doing is making sure that the filament turned the bearing. There's nothing gained by that. The idea behind the hobbing is to make sure that the filament doesn't slip - not the other way around.

if you need a grooved bearing this is how i made them: [www.youtube.com]

That's brilliant Gerard!

Yeah, toothed idler won't help. I'm all for practical experiments, but often theory can save a lot of legwork.

But two driven gears might be useful?

That's what this has now evolved into. Dual hobbed bolt 2ith a gear system. I'll keep you guys updated.

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The original SeeMeCNC extruder has 2 driving rollers.
Though the issue with that hot end for me has always been the extremely shallow pattern on the driver rollers.

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My blog [3dprinterhell.blogspot.com]

I have made a dual Mk6 extruder with two high torque Nema 17 steppers. It is very powerful, and is not slipping at all.

Johan

I will keep the collers in mind. @johan. It would be nice too see some pics of your dual stepper setup.

Hi,
This is the best picture I've got at hand. Both the printer and my laptop with Solidworks is at work....
I will post better photos later.

[dl.dropboxusercontent.com]

@Johan, is there a file for your dual NEMA17 extruder out there somewhere?

The groove might be helpful in alignment of filament but that's it if there is no drive putting teeth on it makes no sense