X axis

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X axis

Postby Art » Mon Apr 19, 2010 3:44 am

I am planning a 4' by 4' and for the X axis it seems that if I used a stepper with dual shafts mounted in center and shaft extensions to both sides to drive the gantry from both sides. 3/4" stainless steel tubing should give me the strength needed and less mass thal solid steel or alumnium. I would use different size pulleys to get gear reduction. 3:1??
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Re: X axis

Postby bdring » Mon Apr 19, 2010 11:25 am

Art,

It sounds like you have the right concepts in mind with weight and stiffness. Are you talking about a rack and pinion system? Ideally you don't want the weight of that motor on the gantry, but it might not add too much to a gantry that size. I would still consider aluminum. It is usually stiffer by mass. The T-Slot system sure are handy for this type of project.
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Re: X axis

Postby Art » Mon Apr 19, 2010 1:18 pm

R&P or belt not sure at this stage. What speeds am I looking at? Belt would be less mass but what about streach?
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Re: X axis

Postby bdring » Mon Apr 19, 2010 2:53 pm

Here is my opinion...

You only need speed for engraving and rapid (non cut) moves. If you can orient the material right, you only need to have high speed engraving in the X, so gantry speed comes down to what is an acceptable rapid move. You will have to figure that out using your own preferences. Acceleration is also something to figure out. If you go with a simple Mach3 control system, laser power and speed are not going to be coordinated so a slow acceleration could result in uneven power/time/speed issues when cutting. That is the theory, in practice I don't see much of an effect on my cutting.

I set the max speed pretty high and set the accel just below where shaking, stretching and stress on the machine would come into play.
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Re: X axis

Postby thechoochman528 » Thu Aug 05, 2010 1:42 pm

bdring,

In your xy part kit dxf, what are the four circles for? I can't seem to find them in any assembly drawings.

thanks,

Brian
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Re: X axis

Postby bdring » Thu Aug 05, 2010 2:03 pm

Good question!

I don't know where those came from. You do not need them. I will remove from drawing.

Edit: I figured it out...they are crop circles placed there by aliens ;)
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Re: X axis

Postby thechoochman528 » Thu Aug 05, 2010 7:39 pm

LOL, good i'm not crazy. I've modeled the entire cutter and had those parts left over i assume they were left over holes from something.

Good news, speaking of modeling. I metioned in a welcome thread that I wanted to Makerbot parts... so far, I've adapted all the parts to be printable. I think I've also slashed the cost of the cutter by almost half, by instead of using the really nice Misumi beams, to going to a threaded rod structure like a reprap. Just a few more things to figure out with the xy gantry and I can continue to print. Although, it's going to take a really long time to print everything out it may be a nice alternative for the penny pincher.
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Re: X axis

Postby bdring » Thu Aug 05, 2010 7:59 pm

That sounds great. You should start a build log. I would love to follow your progress and see some images of your model.
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Re: X axis

Postby thechoochman528 » Thu Aug 05, 2010 11:44 pm

Unfortunately, I can't post a build log...maybe I don't have enough posts yet?
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Re: X axis

Postby bdring » Fri Aug 06, 2010 1:55 am

You just need to be added to "buildloggers" group. You are now a member and can start a buildlog. I want to restrict that forum for buildlogs only so created a special group. Once you start the topic, anyone can post to it.
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