What makes an extruder right handed?

Question

I have been looking to buy a new extruder. One of the options I have seen comes in "right handed" and "left handed". What does this mean? How can I tell what my current extruder is, so I get the right replacement?

can you provie a link to such a setup? It might be a case of mirrored setup (If mounted with the motor in Y and the gripping side going "down", is the motor left or right?) or it might be a case of the pinning (does the motor rotate clockwise or counterclockwise with this pinning?) — Trish, May 13 '19 at 16:25
Opposed to some some views, the orientation sometimes does matter. E.g. it depends on the access to and positioning of the extruder motor. I guess you operate remotely considering you tagged [tag:bowden], so look at the current extruder and how the shaft turns to extrude filament. Please add your machine and extruder setup and a photo would be very welcome! — 0scar, May 14 '19 at 11:13
Quick clarification on my end: gripping side means the side that moves the filament. — Trish, May 14 '19 at 11:23

score 5 · Answer 1 · edited May 14 '19 at 11:03

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The short answer to identify what extruder type you have is the rotation of the extruder gear.

CCW rotation to extrude = right-handed extruder

Detailed explanation is below.

In addition to the other answers, the right-handed designation comes from math and pysics convention that has become a well known mnemonic in engineering practice:

or in its physics coat,

The Right Hand Rule: Figure (a) shows a disk is rotating counterclockwise when viewed from above. Figure (b) shows the right-hand rule. The direction of angular velocity ω size and angular momentum L are defined to be the direction in which the thumb of your right hand points when you curl your fingers in the direction of the disk’s rotation as shown. _reference

In a right-handed extruder,

you place your thumb of your right hand in the direction of the shaft (so pointing it towards yourself in the image of the extruder above) to see that rotation in the direction of your curved fingers leads to extrusion of filament (in counterclockwise direction).

For a mirrored extruder they call it left-handed extruder.

edited May 14 '19 at 11:03

Trish

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answered May 13 '19 at 22:10

0scar

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i'm not quite sure why "the right hand rule" should have any meaning here – darth pixel May 14 '19 at 08:35
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@darthpixel because it is a math/physics convention: a rotation is given as the rotational axis and the speed of it. "10° per second around X" means it rotates with that speed counterclockwise around the X-vector. A "lefthanded" extruder spins - mathematically speaking - around the -X vector. – Trish May 14 '19 at 10:54
but it's not connected to left or right handed extruder. L, I and omega are also not very needed in terms of the question - What makes an extruder right handed? you could also incluse 2*pi*r as it's also loosely connected but it won't help here. left handed means this and right handed means this - why to make things overcomplicated? rotation direction is not really what defines left/right handed extruder – darth pixel May 14 '19 at 12:14
Sorry but it is. Do you think it is called because you operate a right-handed one with your right hand? :) – 0scar May 14 '19 at 12:39
:D i claim that pictures in your answer make it even more curly and they are not making the subject clear. the RHR doesn't explain anything here, the thumb doesn't represent anything so this picture is misleading rather than explaining - that's what i think – darth pixel May 14 '19 at 13:23
@darthpixel I'll try to find a better picture. The thumb is the "shaft", I'll try to clarify that with an edit! – 0scar May 14 '19 at 13:31
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Righthanded: The shaft of the motor and the rotation vector (According to **right** hand rule!) both point out. Lefthanded: the shaft poinsts out while the rotation vector points in. – Trish May 14 '19 at 13:40
@Oscar and Trish please try to imagine a person who is not very familiar with physics - i think such person won't get much from your explanations. What is rotation vector for such person? I'm really trying to imagine the contaxtual meaning of the RHR based on your answers and comments but this still leads me nowhere. and believe me - i'm familiar with physics and at least a bit with 3d printing. – darth pixel May 15 '19 at 04:49

Rosalie W · Answer 2 · 2019-05-14T03:40:02.247

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This is an example of a right handed extruder setup:

And this is an example of a left handed extruder setup:

I believe that you can can choose whatever one you favor. With the right handed setup, you will be pushing down the red part with your right hand when inserting filament. With the left handed setup, you will be doing the same thing but then with your left hand. Personally, I favor the right handed setup (my right hand is my dominant and stronger hand). But, you should be able to choose whatever one you like! Be sure to check it will work with your printer though (extruder holder & hotend).

edited May 14 '19 at 03:40

answered May 13 '19 at 18:16

Rosalie W

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It seems to me that if the stepper is rotating clockwise, then the right handed setup would "push", and the left handed would "pull". Depending on how the stepper is mounted and the layout of the machine, this could be important when choosing which to go with, as it might only be feasible to mount the stepper one way. – linuxdan May 13 '19 at 23:31
With an un-keyed cable, the stepper wiring can be rotated (at one end pins 1-4 mapping to 4-1), to reverse the direction. Of course, it can be done in software too. – Sean Houlihane May 14 '19 at 11:39

darth pixel · Answer 3 · 2019-05-15T09:34:28.257

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when thinking about righ-handed extruder or left-handed extruder it's good to know that there is no magic or any other science rule behind this naming convention. it's just an arbitrary explanation which can be unfortunately misleading. in fact there is visual explanation of this left / right handed name and it doesn't have anything to any "the right handed rule" mentioned in other answers.

it's just this

no physics... no magnetism... no induction... no vectors and no formulas

the other answers present pictures of LH and RH extruders which are of course fine but be careful - there are universal extruders which can be both L or R handed.

like this one

as this extruder has fully fixed filament path and there is no restriction which direction the filament should go - there is no way to describe it arbitrarily

it is left-handed when it works as left-handed and it is RH when it works as RH

edited May 15 '19 at 09:34

answered May 15 '19 at 06:22

darth pixel

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@Greenonline thanx :) in terms of the answer - the picture is worth 1000 words so it was obvious to have both on one picture. as i tried to explain in my other comments in this thread - why to add unnecessary and misleading pseudo-scientific value if just such simple picture will explain it all – darth pixel May 15 '19 at 09:31
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Hmmm... I think both explanations are good. It's nice to have a simple explanation, but it is always handy to have a scientific one too, for greater depth, when needed. :-) Sorry, I got so carried away writing my first comment that I forgot to vote. LOL. – Greenonline May 15 '19 at 09:34

score 3 · Answer 4 · edited May 14 '19 at 10:55

It usually doesn't matter whether you get a right-handed or left-handed one. The reason the two different variations exist is because some people use a dual extruder setup. If you have two extruders it is convenient to have them be mirror images of each other (as this makes them easier to install in use with the filament release lever pointing out to the side). If you have only a single extruder, it doesn't really matter, unless there are other construction restraints.

What makes an extruder right handed?

4 Answers4