Re: [CAD_CAM_EDM_DRO] Re: DRO encoders- Rotary or Linear?

While the linear encoders may be better for the purposes of this list I
think the question is really:
1 - Is my machine such that I would notice any difference?
2 - Even if I could notice a difference is the cost/benefit at a point that
makes sense for me.

I run my Bridgett my Bridgeport series II on Gecko G320 drives with rotary
encoders on the motors. The accuracy and precision with the rotary encoders
is more than adequate for my purposes. It will easily hold to less than
.001" and I can sell all the stuff I produce on the machine. Spending the
money to upgrade to linear strips would buy me nothing as the items I am
producing would not become any more valuable and no one would pay more money
for then. It is all a balancing act to get the accuracy and precision needed
and not waste money getting more. Also remember what the rest of your
machine is capable of. Putting on super high resolution linear encoders on a
mill drill conversion is probably a waste as the rest of the machine will
have enough play and flex that you will not likely see an improvement. Also
remember that setup of the part can have a huge impact on machining
precision. A weak setup will introduce more inaccuracy than the difference
between linear and rotary encoders. Ditto with thermal expansion. So, if you
are not using flood with the coolant being held to a relatively constant
temperature than you will also have inaccuracy.

In summary, my point is that you have to consider the whole and not just
focus on one part. Like so many things in this hobby it is easy to get into
a pissing match where the claims of what is required no longer fit the
reality of most machining much less hobby machining. So if you really feel
your setups will be rigid enough to allow machining to .0001" and you will
control the temperature, and your machine is capable of moving that small an
increment, than maybe the linear encoders will make sense.

Tim
[Denver, CO]

----- Original Message -----
>
> Linear - without a shadow of doubt. Here's why :
>
> http://www.heidenhain.com/posmeas.html
>
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