Re: Machining Delrin at home (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 19 Jun 2007 20:56:59 -0700
From: huil888 <huil888@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Machining Delrin at home (fwd)

Matt -

It looks like someone at this plastics distributor is a bit confused. 
Actually, this information is incorrect, both as to the breakdown 
temperature and thermal decomposition products of Delrin (Delrin is a DuPont 
Co. trademark for acetyl copolymer).

When heated above 230 degrees C (not 200 deg F) Delrin begins to release 
formaldehyde, not ammonia. The odor of formaldehyde is very distinctive, and 
causes immediate coughing and tear formation.

When burned in air, Delrin decomposes and releases formaldehyde and various 
isocyanate compounds, all potentially toxic. Luckily, during machining of 
Delrin, it's very hard to get it hot enough to release formaldehyde unless 
you create great friction  by the use of very dull cutting tools operated at 
high speed.

The only time I have ever seen any evidence of thermal breakdown of  Delrin 
during machining was by the use of a very dull router bit in a high speed 
router (spindle speed 25,000 RPM).

The melting point of Delrin resins is around 350 deg F, and Dupont 
recommends that the molding temperature for Delrin resins not exceed 446 deg 
F. So, it's probably not a good material for spark-gap electrode holders
where anything contacting the Delrin would get much hotter than about 300
deg F.

All the MSDS (Material Safety Data Sheet) for DuPont plastics (including 
commonly used plastics like Delrin, Lexan, Kevlar, etc) can be found on 
Dupont's website at:
http://msds.dupont.com/NASApp/msds/Mediator?sec=searchSection&sub=searchInitial

Regards,
Scott Hanson





----- Original Message ----- 
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, June 17, 2007 5:47 PM
Subject: Machining Delrin at home (fwd)


>
> ---------- Forwarded message ----------
> Date: Sun, 17 Jun 2007 16:01:24 EDT
> From: Mddeming@xxxxxxx
> To: tesla@xxxxxxxxxx
> Subject: Machining Delrin at home
>
>
> Hi All,
> For those contemplating machining Delrin at home (eg. in the  basement), I
> found this on a plastic vendor's website
> "Acetal plastic (sometimes known by the trade name "Delrin") is a  very
> hard
> plastic that is valued by machinists because it can be machined to
> tolerances
> of .001". It is more slippery than UHMW Polyethylene. It can be  machined
> with any metal- or woodworking tool. (woodworking tools should take  tiny
> cuts
> per pass - this stuff is HARD).
> Safety Information
> DO NOT ALLOW THIS PRODUCT TO HEAT UP PAST 200F. It will outgas  ammonia, a
> toxic gas, AT LETHAL LEVELS."
> If your primary tends to get very hot, or you need a base for a  static
> gap,
> etc., perhaps one should consider the above in choosing materials  for an
> indoor coil. For outdoor only use, probably OK, but machine only in
> well-ventilated area only.
> Hope this is of use to someone.
> Matt D.
>
>
>
>
> ************************************** See what's free at
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>