Re: [CAD_CAM_EDM_DRO] Re: Questions about mill enclosures..

Hi Ballendo,

You may well be right regarding Lexan, thanks for the heads up - I will
do some more reading before I continue to use WD40. The mist coolant
"may" also be a long term problem, but I'm pretty sure it is not a
hydrocarbon base, I'll have to check further.

To be honest, I have used clear acrylic covers (usually 1/8" sheet from
Home Depot) for several years and have cleaned it with WD40 without
significant crazing but a bit of discolouration - not enough to worry
about. I only went over to Lexan in early December - out of frustration
with the Acrylic cracking. If there is going to be any crazing of the
Lexan, it probably hasn't presented itself yet - although I may have
already planted the seeds...

In a couple cases the acrylic has cracked around a screw - even though
I use oversize holes, flat washers and only gentle tightening torque.
These are generally minor and more common when the hole is close to an
edge. I have three covers over my reduction belts - for X, Y & Z and
what has annoyed is the large cracks that have occurred after I've
bumped the Y and Z covers which are often around (my) knee height. In
both cases I only bumped the covers relatively lightly and would not
have expected the size of cracks that occurred. It's not like the
covers are stressed at all.

For added strength, I've gone to 1/4" Lexan for my chip shield and had a
devil of a time bending it! Even with heat, it remains extremely tough
and springy to bend! I can appreciate how it can stop those little
projectile thingy's so effectively... As for the belt covers, the
novelty of watching the belts turn has pretty well worn off so when I
replace them (soon) I plant to use sheet steel.

Cheers, Peter


ballendo wrote:

>Peter, that's an interesting observation.
>
>Most plastics suppliers will tell you that polycarbonate is more
>sensitive to aromatic hydrocarbons, and will craze in the vicinity of
>many metalworking fluids/ solvents. Whereas acrlic is not affected
>nearly so much...
>
>Did your acylic covers and enclosures crack due to localised
>mechanical stress? (becasue as you say, acrylic is not near as "tough"
>as polycarbonate...)
>
>Ballendo
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