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Frame proportioning, gear pitch and software settings.

Posted by nh3oh 
Frame proportioning, gear pitch and software settings.
June 13, 2011 09:24AM
Hi, folks,

I want to built a wooden Repstrap like Wolfstrap.

There are two way to drive the X &Y axis :
by threaded rods and nuts
by belts and pulleys

I think threaded rod and nut should be more precise and does induce less strength into the basis frame than the other way, but if Mendel uses belts , must have good reasons for that.

What are those good reasons?


Now, do the Mendel software settings allow to use any screw lead (or pitch ) and different stroke length of axis than the original design?

In other words, if I built a customized frame with my own proportioning , size and gear factors, will be possible to tune-up settings to run it properly ?

Thanks for answer.
Re: Frame proportioning, gear pitch and software settings.
June 13, 2011 03:03PM
Should be


__________________________________________________________________________
Experimenting in 3D in New Zealand
Re: Frame proportioning, gear pitch and software settings.
June 13, 2011 04:57PM
Great! if it's so.

And what about screw versus belt?
Re: Frame proportioning, gear pitch and software settings.
June 13, 2011 05:02PM
could be that steel screw ( heavy in comparison with a belt that weights nearly nothing ) has too much inertia?
Re: Frame proportioning, gear pitch and software settings.
June 13, 2011 07:48PM
Have you considered the 2 motor approach similar to a Prusa for the z axis?


__________________________________________________________________________
Experimenting in 3D in New Zealand
Re: Frame proportioning, gear pitch and software settings.
June 14, 2011 02:54AM
Threaded rod drive is very slow unless you use multi-start lead screws.


[www.hydraraptor.blogspot.com]
Re: Frame proportioning, gear pitch and software settings.
June 14, 2011 03:06AM
Thanks a lot guys, I will think about and come back later if needed.
Re: Frame proportioning, gear pitch and software settings.
June 14, 2011 03:28AM
Also, 3D printing demands a lot of "mileage" from the header. Expect to run threaded rods at the stepper's full rpm for hours. Typical steppers can do 500 rpm without acceleration, 1000 rpm with acceleration (rule of thumb).


Generation 7 Electronics Teacup Firmware RepRap DIY
     
Re: Frame proportioning, gear pitch and software settings.
June 14, 2011 04:17AM
So, what should be understanding ?

That screw isn't good way to drive 3d printer ? even with special screw made for cnc machines ?

I don't want to innovate just to make the simpler but reliable printer I can.
Re: Frame proportioning, gear pitch and software settings.
June 14, 2011 06:05AM
Multi-start ball screws give more accuracy and less backlash, but have a lower top speed and accelerate slower and cost ten times more than belts.

It is questionable whether the extra accuracy makes any difference when extruding as the accuracy of the filament is the weak point. No point in positioning the filament with 0.005mm accuracy when it is 0.3mm wide +/-10%.


[www.hydraraptor.blogspot.com]
Re: Frame proportioning, gear pitch and software settings.
June 14, 2011 09:07AM
Then is the end point of the topic about printing and the start of a new one if it is under scope to use the printer with a router.... {;-)

Thanks a lot....
Re: Frame proportioning, gear pitch and software settings.
June 14, 2011 09:46AM
Yes if you want to build a router then ballscrews are the way to go, but if you also want to extrude plastic with the same machine it will always be a compromise between stiffness for milling and speed and acceleration for FFF.


[www.hydraraptor.blogspot.com]
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