Date: Thu, 16 Oct 2014 16:58:42 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
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From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Vacuum System Parts on 1.9 - "Y's" and Constrictors...
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At 08:17 AM 10/16/2014, Ryan Perry wrote:
> - "Y" from the line off the passenger side of the Plenum on the smaller
> 3.5 branch that goes to the Charcoal canister = 1.4mm or roughly a 1/16
> drill bit.
This one I'm sure matters, as it controls the flow rate through the
canister (and the amount of unmetered air, aka vacuum leak, into the
manifold), and a #54 drill bit would be just right, or a 1.4 mm
bit. 1/16" would be almost 30% more hole area, so definitely a
non-preferred alternative. If you do that, make it fairly thick; I'm
guessing that a half inch thick might make an appreciable difference
on a hole this size, but it's strictly a guess. Maybe
>I haven't contacted my local VW dealer but they are usually pretty arrogant
>when it comes to anything built prior to 2K and all my online research
>leads to NLA.
>Thoughts on should I or ways to do this? David you mentioned a greased wire
>with JB weld...that sounds doable.
Your life here will be easier if you get a 10x loupe and a set of
dial or digital calipers (or "old-fashioned" vernier calipers if you
have good eyes) that read thousandths (beware, some of the cheap ones
read hundredths) of an inch. Price for the calipers from under ten
bucks on sale at Harbor Freight to well over $100 for name brands
like Brown & Sharpe or Mitutoyo. The digitals are nice but you have
to replace the LR44 battery periodically even if they're not used,
unless you remove it. Or a 0-1" micrometer which is less versatile
but more repeatable, also a large price range. Some micrometers have
a vernier scale that lets you read ten-thousandths, well beyond what
you need for this.
The orifice plate has to be fairly thin, or resistance will be too
high. Someone with a lot more theory than I have could compute a
larger hole in a thicker plate to work equivalently, but
You can get ten used #97/.006 carbide circuit board drills with 1/8"
shank for ten bucks
http://drillbitsunlimited.com/006-97-015mm-Solid-Carbide-Drill-Bits-P2372675.aspx
-- but carbide bits are extremely brittle and it's very unlikely that
you could use them successfully without a drill press. If you have a
drill press and can secure work to the table, these should work great
in steel or JB Weld. They might be grabby in brass. If you ended up
having me make you one I'd machine it from brass, aluminum or steel
and use these drills to pierce the orifice. With steel drills you
could use a pin vise or a hand-held Dremel with a miniature chuck;
but I don't think steel drills are readily available in size smaller
than #80, which is .013 (and cheap steel drill bits this small are
pretty horrifying under the microscope, kind of a stretch to call
them drills. I presume ones costing $5 each are better).
36 AWG bare wire is .005" diameter; I'm guessing that with a light
coating of oil that might be just right. 34 AWG is .006. Enamelled
wire will be oversize. For good handling steel music wire would be
ideal and is available in .006" -- going price seems around $100-150
a pound! These folks sell cut lengths by special order:
http://www.hanessupply.com/itemdetail1.aspx?CategoryText1=Janitorial+and+MRO+Supplies&CategoryText2=Wires&CategoryText3=Music+Wires
. I would mold the epoxy to some reasonable thickness, and then
after it's cured drill into it with a 1/16" or whatever bit to get
the actual orifice plate down to thinner than 1/16". You'd then use
the music wire from the other side to re-open the hole. You might be
able to do that while molding by embedding a greased rod; that would
work better with soft copper wire than music wire unless you made a
right-angle bend in the end of the music wire ahead of time. If
molding directly into a plastic tee, I'd use a greased rod fitting
the tee to control the overall thickness.
Another way, much easier if it works, would be to use a small sewing
needle to barely pierce a piece of brass shim stock so your 34-ga
wire would pass through but a 32-ga wouldn't. It might take ten
tries to get it right but very little investment for each try.
You could fabricate a square orifice of the same cross section by
slicing up a .005 (.0053 would be exact) leaf from a feeler gauge --
long piece on the bottom, two short pieces glued down with a third
piece to space them, then another long piece glued on top after
removing the spacer. Exercise for the reader how to couple to it;
and probably a lot of trouble making it short enough.
Overall my first suggestion would be make a proper one from metal on
a lathe or by using a drill press and vise; second to try piercing
thin (.010?) brass with a fine sewing needle mounted onto the end of
a screw so you can control how deep you pierce. You could then cut
this out and embed it in a JB Weld plug.
Yours,
David
