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Author Topic: Machine isnt performing true
CSPURGEON
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Posts: 18
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Post Machine isnt performing true
on: October 31, 2012, 02:17
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First off I want to thank Sandy for getting me my complete gondola quickly!

So tonight everything was assembled and set up, but my outcome was not exactly what I was looking for.

I have attached photos of each settings (input and setup), any guidance would be greatly appreciated.

Image
Image
Image

sandy
Administrator
Posts: 1448
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Post Re: Machine isnt performing true
on: October 31, 2012, 17:40
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Hello, glad you got it safely (and completely this time)!

Right there's two things jumping out at me, the first is the general distortion (it's shaped all wonky, big top, little bottom), and the second is some kind of skipping (the distortion is not regular - there's places where there are overlapped lines).

The distortion is just (ha) misconfiguration. Looking at your setup page, the home point is suspect. When you do a "set home", do you actually get the gondola hanging at that point? Because it places the gondola very very high up - in fact, it has the gondola hanging in space in between the sprockets. If you're using "set home" and the home point in this way, where do you put the gondola when you first lock the motors? I'm assuming that you have already done the "upload machine spec" as well. Nothing will make _any_ sense without that 🙂

The second thing is the skips - starting about halfway through there's some stuff going wrong, the rows overlapping, not starting where they should, not finishing where they should. Right, this is a bit more tricky to get right - it's a tuning issue. Basically your motors don't have enough oomph to lift the gondola up to their extremes, or alternatively to lift your counterweights up at the opposite extremes. In my experience, I've fixed this in two ways - either add weight to one end of the cord - that is, to the gondola or to the counterweight - or by increasing the power that you're suppling to drive the motors.

This is the reason I use variable voltage power supplies really: if it starts struggling you can just give it another couple of volts and it usually gives it a bit more strength, at the price of running a bit hotter and a bit noisier.

Better balancing is the more "elegant" way to do it, but it doesn't look like you've got much weight on anyway - not much you can do. If you've got a variable voltage supply, try that, otherwise try subtracting a little weight from the counterweight or adding a little weight to the gondola. I use a bag of change taped onto the stabiliser.

good luck!
sandy noble

CSPURGEON
Newbie
Posts: 18
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Post Re: Machine isnt performing true
on: November 1, 2012, 23:32
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First off Sandy, thanks for everything! I have figured out a few things from your advice.

Start off with, everyone point at the American and laugh at him for messing up the metric system everytime he (me) uses it.

Second, I adjusted the weights by reducing each by two washers.

Third, the page size and placement offered lowered resolution from what I could tell. I reduced the image and paper size.

Lastly, I PRINTED MY FIRST LEGIBLE PRINT!

Thanks again!

CSPURGEON
Newbie
Posts: 18
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Post Re: Machine isnt performing true
on: November 2, 2012, 01:30
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Here is a link to what I was able to produce, sorry cant get the attachments to work right

http://www.diyprojex.com/?attachment_id=371

sandy
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Posts: 1448
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Post Re: Machine isnt performing true
on: November 2, 2012, 07:51
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Huzzah! Well done - that's a regular shape, and once you've got the shape sorted the rest is pixel / pen tuning, and to be honest, that's much easier to see through experience than it is to explain in words.

There's actually nothing explicitly metric about the system, you can use any unit you want, but I guess the default for the sprocket circumference (95 mm per revolution) is in mm, and it all kicks off from there.

happy scribbling!
sn

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