This is all very useful. Presumably the locking up problem would go
away if the whole barrel were above the melting point?
Sorry to hear about your back - get well soon! (And again to Simon if
his leg's still a bit dodgy.)
Yours
Adrian
[
staff.bath.ac.uk]
[
reprap.org]
Quoting Forrest Higgs :
> Some of this might be of use in Adrian's Wood's Metal work, so I'm
> passing it along.
>
> I sloped on down to the hardware store this morning with my calipers.
> Standard American plumber's and electrician's solder comes in a
> nominal 1/8 inch diameter. In reality this solder is 0.12 inches in
> diameter (3.048 mm). You can fit it in the 5/32 diameter hard copper
> tube of my low thermal inertia extruder with a tiny bit of leeway.
> You have to be very careful when you cut it and straighten it,
> however.
>
> I bought a roll of the acid core and made a few quick tests with it.
> Using pliers I was able to get it into the test barrel and extrude a
> bit of it. After a while, however, I was unable to pump it. It
> appears what happens is that at the top of the melt zone in the
> extruder barrel the solder and the copper barrel make a tight bond
> which basically locks up the barrel Making the barrel hotter just
> moves the melt zone up the barrel a ways and keeps the lock.
>
> This seems to suggest that the extruder barrel needs to be made of
> some metal which the solder will not easily wet. Nichrome 80 comes
> immediately to mind, but I am sure that there are many others that
> would fill the bill. The wetting might be a aggrevated by the acid
> core solder, but I suspect not.
>
> Given that Wood's Metal also has a high lead/tin content you might be
> facing the same situation there. It will be interesting to see.
>
> I somehow managed to cramp a muscle in my lower back, so I may not be
> on-line for a while till it unkinks.
>
>
>
>
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