[Amps] Workshop Danger

[Roger (K8RI)]

I have a machine shop.  ALL machine tools are dangerous.  The less 
knowledgeable and experienced the operator, the more dangerous.

However, because of its characteristics, I would rate the fly cutter as 
one of the more inherently dangerous tools.  Never wear long sleeve 
shirts around one (or any machine tool)and they are not meant to be used 
in a drill press.  I've not seen any drill press sturdy enough to handle 
one safely.  I've seen it done, but never in a machine shop!

OTOH the lowly drill press is really danger in disguise.  When drilling 
steel or Aluminum that long curl of metal that indicates a sharp bit 
doing its job will happily remove a finger(s) just by trying to knock it 
out of the way.

You can get a nasty cut from just picking up an end mill improperly.  I 
have large face mills that have many cutters and they are sharp both on 
the face and sides, plus the 5 1/2" weighs about 10#.  It's like picking 
up a 10# knife by the sharp edge.

I said ALL tools are dangerous. A friend and electrician was working 
several stories up, with a large powered hand drill.  The bit grabbed, 
the cord became tangled and removed his thumb, "by pulling it out!"

Cutter speed?  Too slow can be almost as dangerous as too fast, 
depending on the machine and cutter.

Now when it comes to holes for tube sockets we are not talking precision 
and usually have a fair amount of leeway so the socket doesn't know if 
the hole was cut with a metric or fractional hole saw.
Be it fractional or metric you can usually get one of the other type so 
close you can't tell the difference. Some are actually the same dimensions.

Personally, I don't like hole saws as it's difficult to get a clean cut 
with one even when I have it mounted in the big Bridgeport mill.  So I 
often use fly cutters of which I have quite a number.

Once the hole is cut there are mills that will cut a radius or rounded 
edge. I set up the piece on an indexing table, center it and then move 
the piece so the bit will radius the edge of the cut.  It's kind of a 
pain to set up as the rotary indexing table weighs over a 100#, has to 
be aligned and centered using a dial indicator, but the results are out 
standing and look good.

Yes I consider the fly cutter inherently dangerous, but so are almost 
all tools in the hands of the inexperienced. There is a lot of power in 
that spinning head, be it a lathe, mill, drill press, or battery powered 
hand drill..

Learn how to properly use the tools and tool room safety.  Ever see a 
benign surface grinder take too big a bite? <LOL>  I saw one put a piece 
of steel about 1/2 X 4 X 10" right through a concrete wall.  What if 
some one had been standing there or bent over to get a better look at 
the work?

On 9/13/2013 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

If you ever use a good milling machine, drill presses will forever more 
look pretty fragile!  They are still available for pennies on the 
dollar, but as the economy recovers, or thy keep telling us tat it is, 
those prices are coming back up.

73

Roger (K8RI)