Re: [CAD_CAM_EDM_DRO] Re: um, is the (Chinese scale) dro acting wierd?

ok, it happened today again (a few times). someone had mentioned about
taking a look at the scale readout as well. and sure enough, they've both
skipped. guess this _IS_ the scale.

another thing. i actually saw the y axis readout skip the .200" inch when
i turned the speed knob on. it happened once this way. (btw, it also
jumped by .100" too at some time)

then, i noticed that the z axis also did the same!

and the x axis too. unless i read the cad drawing wrong, when i went to
counterbore, i noticed that is wasn't centered (it was off by less than
.100" but still problematic.). i had to go back and reset the x to do this
and redrill the hole (now it's oblong)

so, what do i do? how do i shield the cable? and is this each cable from
each other? i assume that the scales are grounded since they are mounted
to the base.

On Thu, 18 Aug 2005 19:44:39 -0700, fignoggle <david@...> wrote:

>
> thanks for the info. interestingly enough, the first time it happened was
> when i changed a bit from the drill chuck.
>
> the other thing i've noticed since the beginning was that there's "noise"
> on the display. the digit counters lightly flash as if there was some
> frequency disturbance.
>
> i just wanted to make sure that it was NOT the display itself. is this
> right?
>
>
>
> On Thu, 18 Aug 2005 21:15:22 -0000, klauszietlow <klauszietlow@...>
> wrote:
>
>> This is indeed a problem with the Chinese scales.
>> They are quite sensitive to noise (poor grounding, long unshielded
>> cables...)
>> A jump of 0.200" is just one bit flipping in the scale, since they
>> count 0x5000 (hex) counts per inch. I have seen this as well on
>> several occasions.
>> It's quite annoying, but at 0.2" you at least have a chance of
>> noticing it.
>> There is a good chance that it skips other distances as well that you
>> might not notice, but that will still ruin your part.
>> Is there any correlation when it jumps to something you are doing,
>> like turning on the spindle?
>> This stuff is hard to deal with, since you don't know if it's fixed
>> for good after you add lets say a cable shield or change the routing...
>> Klaus
>>
>>
>> --- In CAD_CAM_EDM_DRO@yahoogroups.com, fignoggle <david@f...> wrote:
>>>
>>>
>>> i just noticed this the other day when drilling a series of holes in a
>>> plate.
>>>
>>> all measurements were spec'd, i just had to read off the dro to get my
>>> locations.
>>>
>>> after the second hole going onto the third, i noticed that what i was
>>> about to drill did NOT match up with the dro reading. it was off. so i
>>> stop and check my math, etc.. this happened all throughout the
>> operation.
>>>
>>> same operation yesterday and noticed it again after zeroing x and y.
>>> knowing that something was wierd, i ran the axes to random points to
>> check
>>> before i started drilling.
>>>
>>> and then the strangest thing. i saw the dro literally jump by .200" by
>>> itself. WTF? it happened all over the place and ONLY in the y axis.
>> from
>>> 1.000 to 0.800., etc..
>>>
>>> so, is this my scale? dro? cable?
>>>
>>> you can see the setup at my site. it's the chinese scales and dro
>> like you
>>> see at lathemaster.com.
>>>
>>> thanks!
>>>
>>> --
>>>
>>> here's the hf mini mill dro/cnc mod!
>>>
>> <http://www.fignoggle.com/~fignoggle/hFCn66Ghejx8Jwia3Kl32ReQ/themachine/>
>>
>>
>>
>>
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--

here's the hf mini mill dro/cnc mod!
<http://www.fignoggle.com/~fignoggle/hFCn66Ghejx8Jwia3Kl32ReQ/themachine/>