[Amps] Workshop Danger

[Paul Christensen]

For the creation of specialized parts and plates, I've started using the 
same vendor that produces my PC boards.  No room for a machine shop here, 
and honestly, I'm not much good beyond a drill press and jig saw.

The CAD software is called eMachineShop.  So far, I've had them produce 
plates with several rectangular holes for Molex connectors that use 
retaining end tabs.  One can control every aspect on the X, Y, and Z axis. 
Last month, I used the software to re-create a small tapped block of brass 
used to hold a switch assembly on a Bird PEP wattmeter board.

Since childhood, I've been creating plate cut-outs with a series of drilled 
holes inside the outline perimeter, followed by a hand nibbler, then 
finished off with a flat file for square holes; semi-round for circular 
holes.  Two tools I've depended on to get any kind of precision with manual 
cutting methods: (1) a General brand precision metal ruler; and (2) a 
high-quality caliper.

The big "negative" when using the CAD software is the cost.  You can't 
accomplish any project, no matter how simple, for less than about $150 for a 
prototype.  The high cost is mainly due to setup fees.  It makes much more 
sense to use these vendors when quantities are involved.  By contrast, I 
don't know what my projects would cost had I taken them to a commercial 
machine shop -- but I suspect it would be similar.

Paul, W9AC

----- Original Message ----- 
From: "Bob Sullivan" <robert at isquare.com>
To: "Jim Garland" <4cx250b at miamioh.edu>
Cc: <amps at contesting.com>
Sent: Friday, September 13, 2013 8:54 AM
Subject: Re: [Amps] Workshop Danger


Jim,

I could not agree with you more! Fly cutters should be simply tossed away. 
For large holes I pay the freight and take the panel to a local machine 
shop. For a few dollars I get pretty large holes at no danger to myself. 
:-)

73, Bob
WØYVA
http://www.isquare.com/personal_pages/ras-hardware.htm

On Sep 13, 2013, at 8:24 AM, Jim Garland wrote:

> My least favorite part of homebrewing an amplifier is making the meter
> cutouts and tube socket holes. Last evening I cut three 2.90 holes for
> GU-74Bs and survived the experience. I have a set of hole saws, but not
> metric ones for Russian tubes, and therefore had to use a fly-cutter. 
> IMHO,
> fly-cutters are the most dangerous tool in a workshop. I hate the things. 
> I
> securely clamped the sheet aluminum stockl to the bed of a large
> (floor-mounted) drill press, set the drill press on its slowest speed, and
> used aluminum cutting fluid. One has to advance the fly-cutter VERY slowly
> to prevent the cutting tool from grabbing the aluminum. If that happens, 
> the
> sheet aluminum is likely to go flying around in a big circle like a sythe.
> The other danger is absent-mindedness, which can lead the drill press
> operator to reach in with his fingers to remove a piece of aluminum 
> debris.
> Fly-cutters should never be used with a hand drill, as I stupidly tried 
> once
> as a teen-ager. They absolutely require a large floor-mounted drill press
> with a sizeable bed.
>
>
>
> 73,
>
>
>
> Jim Garland W8ZR
>
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>

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