backlight length ... and opportunity

[Steve Jackson-5]

Tom N0SS wrote:

"IF you wish to cut the LED yourself, be aware that
the plastic is pretty brittle, AND pretty hard as
well. So you should probably consider either sawing it
(fine tooth blade) or grinding it (a little at a time)
to length ..."

Tom:  

My K1 backlight is one of the "extended" 1.41" long
versions.  While I see that you've offered to re-cut
this piece to the recommended length, I'm of a
different sort of ham, and respectfully decline your
offer.

What I'd rather do is to take this opportunity to
learn what tool is best used, and how it is best used,
to cut material of this type.  So far, I've heard
general comments such as "razor saw" and so forth.  It
isn't so much the cutting itself, but the chance to
work with a material I've not done a lot with before.
It's all about opportunity, and this is a plus, not a
minus.

Many people have gratefully commented to me over the
years about my blunt specificity about tools.  For
example, I have unequivocally stated here and
elsewhere a preference for the Edsyn Soldapullt DS-017
desoldering tool and cousins ... and that
recommendation is backed up by decades of real-world
experience and more than a few hundred dollars spent
on 'alternatives.'  For a handheld, low-cost unit,
this specific model remains without peer.  My 1999
vintage K2 #0771 runs 24x7, and has for years (indeed,
I'd wager it's the K2 with more 'power hours' than any
other in the world), and I am not ashamed to mention
it's seen more than it's share of the business end of
my DS-017.  #0771 got to be this good because of the
seasoned constructor who built it AND his tools.

Now, as for my point:  I'd like to know, by brand name
and source, what is (are) the best tool(s) and
blade(s) used to cut whatever thermoplastic the
backlight is made out of, and how that tool is best
used -- and why.  I'd also like to know the specific
name of the material itself, so that I might learn
more about the properties of such.

So prepared, tutored, and equipped, I'll be a better
craftsman.  Tom, your so-called 'error' has simply
yielded me an opportunity.  And I know that I'm not
the only person reading this that feels the same way.

73 Steve KZ1X/4


       
               
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[Don Wilhelm-3]

Steve,

I have not dealt specifically with the backlight assembly, but I have cut
many thermoplastics, ranging from small, thin pieces to 4 x 8 sheets of
thicker material.

I have cut them on my tablesaw, bandsaw, compound sliding miter saw, and a
variety of handtools - usually saws.  There is one caution that I will offer
when using a powered tool - do not linger with the moving blade in contact
with the thermoplastic material, it will melt from the heat and attempt to
fuse the sawblade to the material being cut, and once that fusing is
adequate, the material will break from the force exerted by the blade.  One
must use a blade that has teeth separated adequately to remove the waste
material from the saw kerf repidly, yet teeth spaced close enough together
so the uncut material will not fall between 2 teeth and be shattered.  A
rapidly moving fine pitch saw blade will quickly melt the plastic, so one
must either slow the blade motion down or move the material more rapidly.  I
have used 40 to 60 tooth crosscut woodcutting blades on my 10 inch tablesaw
with success, but both the blade depth and the feed rate must be controlled
to avoid melting - it will vary with the thickness, often it is wise to make
several fast cutting passes of the material with a cool-down break between
passes.

The exact sawblade tooth spacing must be determined by the thickness of the
material to be cut and the angle of attack of the blade on the material
(this is a function of the type of blade and machine being used.

This problem is not normally encountered with hand tool techniques because
the blade moves more slowly, but there is the problem of not having an
adequate number of saw teeth in contact with the material at one time (which
causes breakage), so with hand tools, a finer blade is usually a better
choice.

One tool I have found that is not good for cutting thin plastic materials is
a saber saw - most woodcutting blades will cause chippage or breakage and
the finer metal cutting blades will overheat the material until it sticks to
the blade, then it breaks.

Sorry I have not given exact information, and my tool model numbers would
likely not be beneficial, and the real answer is 'it all depends...'

73,
Don W3FPR

> -----Original Message-----
>
> Tom N0SS wrote:
>
> "IF you wish to cut the LED yourself, be aware that
> the plastic is pretty brittle, AND pretty hard as
> well. So you should probably consider either sawing it
> (fine tooth blade) or grinding it (a little at a time)
> to length ..."
>
> Tom:
>
> My K1 backlight is one of the "extended" 1.41" long
> versions.  While I see that you've offered to re-cut
> this piece to the recommended length, I'm of a
> different sort of ham, and respectfully decline your
> offer.
>
> What I'd rather do is to take this opportunity to
> learn what tool is best used, and how it is best used,
> to cut material of this type.  So far, I've heard
> general comments such as "razor saw" and so forth.  It
> isn't so much the cutting itself, but the chance to
> work with a material I've not done a lot with before.
> It's all about opportunity, and this is a plus, not a
> minus.
>
> Many people have gratefully commented to me over the
> years about my blunt specificity about tools.  For
> example, I have unequivocally stated here and
> elsewhere a preference for the Edsyn Soldapullt DS-017
> desoldering tool and cousins ... and that
> recommendation is backed up by decades of real-world
> experience and more than a few hundred dollars spent
> on 'alternatives.'  For a handheld, low-cost unit,
> this specific model remains without peer.  My 1999
> vintage K2 #0771 runs 24x7, and has for years (indeed,
> I'd wager it's the K2 with more 'power hours' than any
> other in the world), and I am not ashamed to mention
> it's seen more than it's share of the business end of
> my DS-017.  #0771 got to be this good because of the
> seasoned constructor who built it AND his tools.
>
> Now, as for my point:  I'd like to know, by brand name
> and source, what is (are) the best tool(s) and
> blade(s) used to cut whatever thermoplastic the
> backlight is made out of, and how that tool is best
> used -- and why.  I'd also like to know the specific
> name of the material itself, so that I might learn
> more about the properties of such.
>
> So prepared, tutored, and equipped, I'll be a better
> craftsman.  Tom, your so-called 'error' has simply
> yielded me an opportunity.  And I know that I'm not
> the only person reading this that feels the same way.
>
> 73 Steve KZ1X/4
>
>

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