Snake oil?

From everything I have read about 0.9 degree versus 1.8 degree steppers I relayed to this person and they say there is no downsides to his design just better accuracy. I am not even sure how he is achieving this as I see no gears or anything else giving 2:1 ratios but, then again, I haven;t tried to dissect each stl either.

Double XY Prusa i3

What does anyone have to say about this? I mean there has to be a downside, or as I said to him the downside might be outside of what 3d printing cares about.

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I await Skynet and my last vision will be of a RepRap self replicating the robots that is destroying the human race.

Its the belt path which gives the 2:1 reduction, but I can't find a diagram of it. [www.thingiverse.com] is the same idea with a better video attached.

Ahhh, that is why I saw 4 belts not two. Hmmmm.

edit: #1 Yeah, after doing a Google search I see nothing about how a belt is used for this purpose. Lots of pulleys and gears but no mechanism like this. A bigger hmmmm.

edit #2: You know the more I think about this, and after watching that video of yours numerous times, I think what we have is the ancient block and tackle pulley type system working here. Add more turns and twists to that belt and it will reduce it even more and it will always be in multiples of 2. This was the old issue with the block and tackle system as originally designed so they devised pulley ratios then gears. Now I am not 100% sure this is how it is working but it sure seems like it but it has been 40 years since I took this stuff in elementary school.

Edited 2 time(s). Last edit at 10/03/2014 09:10AM by Dark Alchemist.

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I await Skynet and my last vision will be of a RepRap self replicating the robots that is destroying the human race.

The downside is that the belt is a little over 50% longer than the traditional setup, making the positioning less stiff.

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Feign
The downside is that the belt is a little over 50% longer than the traditional setup, making the positioning less stiff.

Wouldn't that be what is called slop?

I was doing the math and my GT2 16 teeth setup is 100 steps per mm so I have .01mm accuracy in my X and Y whereas my Z is 4000 steps per mm so a 4:1 in the X and Y is what I would think would be the sweet spot (especially with tiny circular holes).

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I await Skynet and my last vision will be of a RepRap self replicating the robots that is destroying the human race.

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Dark Alchemist
Wouldn't that be what is called slop?

Informally, yes. You're going to have mechanical play in every pully/bearing and every contact point the belt has, plus then over the long term you may have belt stretching. You'll also whatever backlash would normally be in the system just from the nature of using geared/toothed mechanical components. Some things you may be able to minimize/account for, but I think overall you're just increasing the complexity and points of issue while getting more resolution where it's not as needed. It's just like with gearing motors, you're trading resolution for speed. You can double the resolution so to speak, but you lose half your speed.

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cdru

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Dark Alchemist
Wouldn't that be what is called slop?

Informally, yes. You're going to have mechanical play in every pully/bearing and every contact point the belt has, plus then over the long term you may have belt stretching. You'll also whatever backlash would normally be in the system just from the nature of using geared/toothed mechanical components. Some things you may be able to minimize/account for, but I think overall you're just increasing the complexity and points of issue while getting more resolution where it's not as needed. It's just like with gearing motors, you're trading resolution for speed. You can double the resolution so to speak, but you lose half your speed.

Considering the I3 doesn't have that much speed anyway else it shakes itself apart I am not overly concerned with the loss of speed. Seems 60mm/sec is the sweet spot for the I3 and faster, while printing, is just asking for issues. YMMV but that has been my experience.

Now, I see an Ultimaker doing 150-250mm/sec I know that even half the speed of that would still be faster than the mechanical parts of MY I3 can easily handle.

I just wish I had more resolution in the X and Y and I am very happy with the resolution of Z. I wonder if doing a leadscrew (Z type setup) for X and Y wouldn't actually be better than a belt for this type of setup?

Edited 1 time(s). Last edit at 10/03/2014 02:38PM by Dark Alchemist.

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I await Skynet and my last vision will be of a RepRap self replicating the robots that is destroying the human race.