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Ultimaker feeder gear mod (double helical)

by geodesign, published

Ultimaker feeder gear mod (double helical) by geodesign Jan 5, 2013

Description

This is a double helical (aka. herringbone) gear set for the default Ultimaker filament feeder.

I don't own an Ultimaker yet, but saw many YT videos, and I noticed that the gears on the feeder mechanism are working relatively loudly.

This is because of they straight teeth. Helical gears are invented to ensure permanent contact between gears, as they roll on each other, just like they were wheels. If I have not made any serious mistake, this set will be operating much softer. Awaiting feedbacks on this too. :)

There already are some similar modifications, but none of them are correct from a mechanical point of view: teeth should be bent properly, especially on the smaller gear, to maintain proper connection between the gears.

Dimensions are from "official" lasercut PDF, so everything should be fine.

There are two versions attached of the bigger gear: one with a knob socket, where you can insert a knob for easier manual feeding, and another standard version without any hole for the knob.

_Of course, the "knobbed" version can be used without the knob attached as well, thanks to the lego connector like design._

I also rendered some additional images (orange ones), where you can examine the models.


And here comes the important part:

If someone, who can give proper feedbacks (with an engineer's eye) about the possible weaknesses or faults, would print and test it, I would be grateful for him/her.

Theoretically, although the small gear has a slot for fastening purpose, it can't fall off from the feeder motor's axle, because of the double helical toothing.

If tests confirm, that fastening is unnecessary, I will modify the model.

Any further suggestions are welcomed. Write your remarks and experiences, so I can improve the set.

Recent Comments

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Update, I just designed a spring-suspension to make the extruder quiet: http://www.thingiverse.com/thi...

I heard those capacitor rumours too. But I wonder if they were not talking about electromagnetical noise, rather than acoustic noise.

Concerning noise: the extruder gear does get annoyingly loud when I print with lots of retraction, so I think there is a problem to be solved there. But it's because the back wooden wall acts like a drum or resonance chamber. When I un-hook the feeder mechanism and hold it in my hand while printing, it goes slient.

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Instructions

Use highest resolution possible!

A minimum of 80% filling should be set for the gears.
The knob is designed to be printed with 100% filling, since it is hollow on purpose, where necessary.

UPDATE 1:
Knob updated (gear knob v2.STL) according to smorloc's feedbacks.
Pin thickened from 4,5mm to 4,8mm, shouldn't be that loose anymore inserted into its 5mm hole. Pin's wall also thickened to ensure durability.
Gears still need to be tested in operation.

Comments

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maxy on Feb 16, 2013 said:

Concerning noise: the extruder gear does get annoyingly loud when I print with lots of retraction, so I think there is a problem to be solved there. But it's because the back wooden wall acts like a drum or resonance chamber. When I un-hook the feeder mechanism and hold it in my hand while printing, it goes slient.

maxy on Feb 24, 2013 said:

Update, I just designed a spring-suspension to make the extruder quiet: http://www.thingiverse.com/thi...

smorloc on Jan 19, 2013 said:

I wanted to post you a followup. I am still using your gears on a machine that is heavily used. The updated knob has still proven to be too weak and broke quickly. I printed it in PLA at 100% fill. I prefer turning the large gear by hand, so I am fine without it.

geodesign on Jan 19, 2013 said:

Hi,
Thanks for the info smorloc. Do you think that narrowing the gap a little could make the knob stronger, or is it the printing method itself, which weakens the knob, no matter how I modify the gap...?

Maybe I should increase the diameter of the hole and the pin together... hmm

By the way, does anyone know, where the personal message option disappeared from this new Thingiverse design?

catohagen on Jan 7, 2013 said:

It might not address a noise problem with the orginal gears, but I like your gears, i have seen since i built my ultimaker, that my orginal little wheel wiggle alot, like its not aligned with the motor shaft, and since herringbone gears are difficult to mount/dismount, maybe you could post your design without the herringbone detail, just plain gears....would very much like to print and have your gears on my printer.

geodesign on Jan 7, 2013 said:

I will consider this too.
Check back later! :)

alberton on Jan 7, 2013 said:

I printed this parts in the Ultimaker. The first print came with the layer of teeth of the big gear separated in some areas from the support wheel. I had to use 100% fill and 5xNozzle(5x0.4)
layers top and walls to print it correctly.
What kind of improvement are you looking for or foresight from the use of this gear?
I do not look for noise reduction as said it is not coming from OM gear anyway. I like the noise of the printers so I feel someone is always working in the studio!
I will install it tomorrow and thank you guys for the tips of enlarging sizes to fit in.
By that way if you can share a solidworks or an original model file perhaps we can work on that one too to make any improvements.

smorloc on Jan 7, 2013 said:

Sorry for the delay getting back to you. It turned out that it was more involved, my time was limited yesterday and my crew had wanted access to the printer...

In case you are sizing your models to the material being used, I printed your gear set in cheap (maybe form Amazon.com) 3mm PLA.

I have placed a couple of pictures at https://plus.google.com/photos... that will hopefully help understand my comments below.

I found when trying to mount the gear set that the "little gear" shaft hole diameter was too small. My shaft is 5mm and the opening was 4.7mm. I opened the I/D with a round file until it was a tight fit & would be held on by fritction. I would not have been able to use a set screw since the hole was too far into the motor mount to be used. As JelleAtProtospace mentioned, mounting this was much more difficult than the other designed out there. My approach was to

1. mount the small gear on the motor and position it by eye

2. place/force a large nut into the large gear

3. remove the hobbed bolt until just the end with the needed number of washers on it were sticking out

4. screw (with my fingers) the hobbed bolt into the large gear

5. as the large gear starts to get tight: check the aligned with the small gear & adjust the small gear position

6. Tight the large gear as appropriate, testing for binding and proper meshing with the small gear.

7. Add a washer & the acorn nut. Crank the nut down.

I found that the new large gear would not clear the bolt heads on the clamp assembly, so I had to add an additional washer to the hobbed bolt..

In its final position, I found that the motor shaft was 4.7mm from the end of the small gear. This meant that part of the small gear was not fully supported. This was a result of the gears being wider than the previous ones I had been using. This didn't seem to be a problem in my setup however if the gear was printed at a lower quality or fill, I suspect it might be a possible point of failure.

The gear knob v2 worked much better however I still found it loser than I like. I would suggest widening the pin a tad more and while reducing the hook at the end (so it will be easier to press into the large gear).

I like the gear set, however I agree with JelleAtProtospace on questioning whether this gear set is addressing somethnig that is a problem (noise) and whether the increased difficulty in installing/removing the gear set makes it worth it.

geodesign on Jan 7, 2013 said:

Thanks for the newer feedbacks again.

The D-hole diameter should be 5mm, since in the model it is. Could it be maybe calibration problem, or the behaviour of the freshly printed, slightly melted layer?

(You use cooling fan, I bet, don't you?)

Thanks for the mounting process steps too. Unfortunately herringbone gears are always harder to mount, but I hope it worths the extra job. :)

I know that the motor shaft is shorter, but I can't help that, the herringbone design needed that extra 4mm in width.
Important parts, like this, always should be printed in the highest quality availabe.

Thanks for the exhaustive and detailed feedbacks again!
I will return to this mod a bit later, since currently I am working in a much greater project (which involves this mod too).

Details soon, in another upload, stay tuned! :)

JelleAtProtospace on Jan 5, 2013 said:

I see one potential problem with it: mounting and dismounting will be a struggle. That is one of the design flaws of the printrbot, don't make the same mistake!

This is a solution to a problem though that does not exist in my opinion: the most noisy parts are the motors by far, not the gears on the extruder. Those turn to slow to make any discernible noise.

Rumor has it that some extra beefy capacitors near the stepper drivers (current ones are 200uF) might decrease that noise, as will mounting them in rubber washers + a sprung tensioner.

fastening the small gear is necessary I thing, otherwise it will develop wear from all the retraction.

maxy on Feb 16, 2013 said:

I heard those capacitor rumours too. But I wonder if they were not talking about electromagnetical noise, rather than acoustic noise.

geodesign on Jan 5, 2013 said:

Let's wait for smorloc's feedback about mounting. I hope he will succeed.
The motor's mounting socket lets the motor slide a bit before tightening the screws, that space should be enough to assembly the feeder with these.

Or what are you thinking about under "will be a struggle"?

About the noise:
http://www.youtube.com/watch?v...

On this video you can hear the motor noises in the background, but the louder noise in the "foreground" is made by the default gears. I can recognize this sound even while sleeping, I had heard that for years while I played with Technic Lego gears. :))

smorloc on Jan 5, 2013 said:

I have printed it up however I will not be able to install it until tomorrow. The pin on the knob is very thin and fragile. It is very loose in the big gear connector. It seems like there is room to beef up the knob by increasing the pin diameter, thickening the walls & reducing the the split width...

geodesign on Jan 5, 2013 said:

Your print looks very nice.
I was not dare to design the pin thicker, since I don't know the tolerance of these prints, but now I have some benchmarks, thank you!. :)

First I will only increase the outer diameter and decrease the inner a bit, so the wall will be thicker, but the split width can't be much smaller, because you won't be able to push the pin through the hole anymore.

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