Swirl: Rotate the work around an origin outside it's diameter without twist=
ing the work around it's centerline.
Think "dairy queen ice cream cone top" but sideways.

After this the end will look a bit rough, but after removing excess glass w=
ith tweezers, continue torching it starting at the tip and it will contract=
 into a ball.=20
Alternatively for a less pretty but still effective seal, mash it with a ma=
rver.
The vac seal was made when you gathered the glass and then did the twist an=
d swirl.  This last bit is just appearance/fragility.

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of=
 Sean Breheny
Sent: Wednesday, November 1, 2017 12:14 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Vacuum plumbing

What do you mean by "swirl"? I have tried twisting but it always seems to j=
ust make the leak channel a twisted path but not fused together. Also, twis=
ting and pulling leads to a very tiny, brittle end to the seal. I was able =
to make it "ball up" a little but never become robust enough that I was com=
fortable it wouldn't break easily.

On Wed, Nov 1, 2017 at 12:43 PM, Van Horn, David < david.vanhorn@backcountr=
yaccess.com> wrote:

>
> Here's the secret:  Once you get it soft, twist and swirl.  This=20
> breaks up the leak channel into tiny bubbles.
> After flame cutting, pull off any excess with stainless steel tweezers=20
> and then torch it smooth.
>
> I've got that technique down cold, and have done hundreds of such=20
> seals without problems, even when running at 50 microns inside.
> Cooler torches help slow things down, a regular propane torch will work.
>
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20
> View/change your membership options at=20
> http://mailman.mit.edu/mailman/listinfo/piclist
>
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