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Worm gear discussion
05-01-2014, 09:17 AM
Post: #21
RE: Worm gear discussion
(05-01-2014 07:46 AM)steamboat Wrote:  Would be nice if someone could print out my gear and tell me the outer diameter.

I have it on the printer now, but not sure how I am going to accurately measure it as I don't have calipers. I will try to find a metal ruler if I can but its not going to be very accurate.
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05-01-2014, 09:47 AM (This post was last modified: 05-01-2014 10:18 AM by jmccartney.)
Post: #22
RE: Worm gear discussion
I don't have my good ruler here at home, but mine printed probably 14.5-14.4 maybe. Too hard to tell. Its certainly between 14 and 15...

I am willing to bet its exactly right.

I printed using makerware @ .1mm. It took me 20 minutes to print the one i printed so I tried to get you as accurate print of the stl as I can on a makerbot rep 2.

Its very sturdy and nice. I can remeasure and take a pic in the am, but I think you got your answer. Your stl is fine, its the printer but I am not sure its enought to matter...Interested to know. How fast are you printing?
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05-01-2014, 04:28 PM (This post was last modified: 05-01-2014 04:33 PM by steamboat.)
Post: #23
RE: Worm gear discussion
(05-01-2014 09:47 AM)jmccartney Wrote:  Too hard to tell. Its certainly between 14 and 15...
Thank you for this test. This helps to understand things better. It makes clear that different printers will do it different. So you can tell people "Your printer is doing it wrong" but this doesn't solve the problem if you like to print it.

This fact let me keep design things a little bigger in size. Especially gears with less teeth have the need of accuracy. To explain this think about a spur gear with only two teeth - it wont work. So 8 teeth are at the edge to be functional. But this needs exact teeth and suitable axis distances. That's why I started with 16 teeth! But with our/my printer it is not possible to print smaller teeth than module 1 - and this requires a to big gear diameter as shown above.

I don't know if and how people can change the print dimension in their special software - I can. But as you demonstrated by yourself people even have no chance to measure things as exact as needed here. But this - or every other - gear is the key to a trouble free = fun project of a centipede robot. Maybe the public printable Centipede will be a macropede and not a micropede?

To solve the problem with the gear dimensions people could print out a test fixture with 4 axis. This could be available with different axis distances of let say 12.25 - 12.50 - 12.75. After testing this on the personal printer they could choose a chassis design with the matching axis distance. If they can NOT make this test fixture running they even know that they should print RepWalker as Shellmo base instead...
What do you think about this? To complicated?

I also could hold the axis distance variable by fixing the axis plates with screws - but this needs extra skills and could become loose.

(05-01-2014 09:47 AM)jmccartney Wrote:  How fast are you printing?
I printed 8 gears at once in 20 minutes. But this does not say anything about speed. You did it in a 5 times finer print resolution with a layer height of 0.1 mm not 0.5 mm like me. I printed the base layer with 7 mm/sec. All next outer perimeters with 20 mm/sec. Inner perimeter and infill (there is not much) with 30 mm/sec. But I have some doubt that you ever reach this speed because of the short distances to speed up and hold on. I set the XY acceleration to 1000 mm/s².

Are you able to set your layer height to 0.5 mm or 0.25 mm in makerware and for your printer/nozzle?

Rainer
http://www.steamboating.de
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05-02-2014, 12:05 AM
Post: #24
RE: Worm gear discussion
(05-01-2014 04:28 PM)steamboat Wrote:  
(05-01-2014 09:47 AM)jmccartney Wrote:  Too hard to tell. Its certainly between 14 and 15...
Thank you for this test. This helps to understand things better. It makes clear that different printers will do it different. So you can tell people "Your printer is doing it wrong" but this doesn't solve the problem if you like to print it.

This fact let me keep design things a little bigger in size. Especially gears with less teeth have the need of accuracy.

I don't know if and how people can change the print dimension in their special software - I can. But as you demonstrated by yourself people even have no chance to measure things as exact as needed here. But this - or every other - gear is the key to a trouble free = fun project of a centipede robot. Maybe the public printable Centipede will be a macropede and not a micropede?


Are you able to set your layer height to 0.5 mm or 0.25 mm in makerware and for your printer/nozzle?

Your right its a matter of printer capabilities. When printers struggle to match the stl then you get these results. So you have to make a stl that the printer doesn't struggle with like you said.

Honestly at this point I think this is where we are all going to diverge. Anything I make I am targeting an audience on thingiverse that typically can printer at the higher resolution lets say at lest 0.25mm with nothing customized except speed, temp, layer height. (when you talk of these other printer parameters I have no idea what your talking about)

I think this is okay. There is value in building models for different audiences. For a while we have been compromising, but at some point direction needs to be personally decided.

I think this also comes to style to. I usually print when I am sleeping with very large "trays" that can take 7-20 hours to print. I print slow and fine because I am sleeping. I imagine my audience will dwindle and yours Rainer will be ever popular, but I have spent two weeks now and my morale is low and I plan to just make something that works over the next 4 days to regain some confidence in this whole thing. Whether that resembles shellmo much I don't really care at the moment. I need a small win, (like your walker Wink

The max I can print is 0.4mm, I have never done over 0.25 so I have no idea what that even looks like. Lately most things have been at 0.20 because of small parts getting too hot.
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