Re: [CAD_CAM_EDM_DRO] Re: Belt vs. Direct Drive

In this respect I wonder if it is possible to build a very crude machine,
with a worst possible screws and backlash everywhere and try to compensate
for
it in a software to the point of an accurate machine?
Alex

----- Original Message -----
From: CL <datac@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, January 03, 2003 2:26 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Belt vs. Direct Drive


> Tony Jeffree wrote:
>
> > (snip) There shouldn't be any extra backlash if you use the stepped
> > "timing
> >
> >belt" style of pulleys/belts(snip)
> >
> The real answer to this question has always been the same and its is
> based off of *other* information.
>
> What are you building ? What Accuracys and Resolutions must you maintain
> ? How much money do you have, and how much time do you want to spend
> getting it right the first time? THAT is what you need to base your
> desicion on.
>
> To really get direct drive right, you need to do "the math" the very
> first time so that it works as you intend. In actuality, not all of this
> can do that including myself, and even some of the OEM builders ONLY
> find out what is *Right* after making numerous prototype machines and
> then using the best of the best results for the final product. Even
> then, sometimes cost overruns screw that all up anyhow, but in any event
> on a one shot build, If you did your math wrong, you may have to replace
> a lot of components to get it work right.
>
> This all ties in with how much money you have in the budget because in
> the above case, you likely would be purchasing components new to Spec.
> because the "hit and miss" surplus parts you usually find for cheap will
> not always fit into that "mathmatical" device you designed.
>
> However, with Belt drive, again, depending on what YOU are building, you
> can take a hodgepodge bunch of stuff and "make" it work. If you
> miscalculate something or simply "must find a way" to make that 1" lead
> leadscrew work for you for at least a while, A simple belt and pulley
> change and an increase in driver resolution just might help you get by.
> The "swap" of those components is chump change compared to a
> miscalculation on a motor or leadscrew that you bought new to spec.
> So, even though there are strong feelings on both sides of the issue, It
> makes a BIG difference with exactly what you are trying to do and how
> much time, patience and money you have to make it work correctly. There
> is no right or wrong way.
>
> In all honesty, I have yet to see a Router or Engraver suffer because of
> backlash lost in belt. If by chance I did, I'm likely to find the wrong
> belt, wrong pulleys, or wrong concepts applied. Mills may be a bit
> different, yet I've seen plenty of in tolerance work done on belt driven
> converted mills......
>
> In almost all machines, especially the homebrews....... Just put a dial
> indicator somewhere and "Lean" on the machine. Often times there is a
> lot more "Flex" in the framework, that most would agree that any
> introduction of backlash in the belt is frivilous.
>
> Of course the above is my opinion, and I am well aware of the
> differences, gains, losses etc of both methods. It only comes down to
> what one NEEDS.
> Dont forget too, sometimes belt = quiter, direct = noisier. ( I said
> sometimes !)
>
> C
>
>
>
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