RE: [CAD_CAM_EDM_DRO] Re: Opinions on $250 cnc machine

Hi John,

I quite agree with the precision. Using 200 step motors run with a decent
microstepper can do 800 accurate steps per revolution coupled to a 20tpi
leadscrew with zero backlash and you have 0.0000625" per step. Even without
microstepping positioning is well under 0.001". Slow traversals though.

For engraving it may not be an issue but engraving away the copper on a
circuit board and/or drilling holes, the tolerances on the leadscrew might
well cause misplaced pads or holes.

Were I to do it over again (which is probably guaranteed) I would use much
thicker rails but in this case the 1/2" size was dictated by what I had on
hand. You design looks interesting. Any chance you can post a picture of
the bottom axis without the metal plate in the way?

Model Engineers Workshop had an article on turbine type air powered
spindles. I don't believe Dremels have the bearings capable of standing up
and maintaining accuracy.

John Dammeyer

>
> Threaded rod is not the best thing but I do wish I could get
> pics of the detail it will do. It is amazing provided everything
> fits well on the machine.
>
> I'm making a machine that would come Very usable but if one wanted
> precision rod or screws it would be a simple thing to add those
> better parts. It's modular. You can see the x-z assembly in it's rough
> form. Mass -like you said is much better than one might guess.
> A block of poly is maybe half what aluminum is.
>
> There' a "trick" to using this stuff and that "trick" is make it 1.5
> times as thick as you think it should be.
>
> Rigid as can be.
>
> I just think it would be great it a person could have a
> good,reliable,solid, tabletop
> machine for less than $500 for the whole works.
>
> and you can.
>
>
> thanks -John
>
>
>
>
>
>
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