[HBR] HBR-13 Progress

[Shoppa, Tim]

For anything bigger than 1/8 but less than 3/4 inch in sheet metal,  I start with a 1/8 hole then I use a "step drill". E.g.  http://www.mcmaster.com/#step-drills/=rfkfol

Home Depot also sells step drills. The Unibit brand is pretty good.

Harbor Freight also sells step drills. I bought some once when I lent out my real Unibit. They harbor freight stuff will work but they just feel like crap.

I have a mix of Greenlee (inch) and Mouser (Metric) punches for sizes bigger than 3/4 inch (e.g. tube sockets) in aluminum and plastic.

Tim.

-----Original Message-----
From: hbr-bounces at mailman.qth.net [mailto:hbr-bounces at mailman.qth.net] On Behalf Of Ejparagi at aol.com
Sent: Monday, April 07, 2014 8:22 AM
To: hbr at mailman.qth.net
Subject: Re: [HBR] HBR-13 Progress

Hi Scott,
 
Another suggestion for holes in the 1/4 to 1/2 inch range is the use of brad point drills (sometimes referred to as "spur" drills), commonly used on wood and sheet metal.  They are also referred to as "sheet metal  drills."  
Harbor Freight and Sears have sets of these that go to  a half inch in diameter.  They have a very sharp point that is easily  centered on even shallow prick punch marks (steeper angle than a center  punch).  I have used them in both hand held drills and drill presses with  good results.  You might want to buy only two or three sizes that would  receive the most use from a local hardware store if you have a well stocked one  nearby.
 
Working up to a hole with successively larger conventional drills also works well as someone already mentioned.  You could buy a couple of  good 1/16 inch or 3/32 inch drills for accurately locating the intended hole and  then use your existing larger bits to work up to the desired diameter.  Use  a center punch to start conventional drill bits.  I used this method for years, sometimes augmented by a taper reamer until I could afford step drills and spur drills.  By the way, I added to my tool collection over the years  by asking for specific tools for birthday and Christmas gifts.  Make a list and add to it when you think of tools that would be of use to you so you are prepared when someone asks for gift suggestions.
 
Sounds like you are making good progress, and that is what it's all  about.
 
73 es GL,
Ed
WB9RMA
 
 
 
 
In a message dated 4/6/2014 8:03:21 P.M. Eastern Daylight Time, whitebear1122 at comcast.net writes:

When  using the hand drill on the chassis I use a center punch and put a divit into  the aluminum and then come in with the drill at slow speeds.  The larger  the drill bit size the greater error I have.  You bring up a good point  on the sharp bits though.  I'm using my ancient bits which are likely contributing to the problem.  I'll buy some new bits this week.

On  my 17" x 12"x 3" chassis I put a piece of 4"x4" cedar inside the chassis to  drill against, then I use some Quick Grips to hold the chassis to the bench.  Center the drill bit on the divit and drill.  

Are  you able to get accurate location for large bits like 3/8" or 1/2"?  
The  small ones are good but I seem to get more error with the larger ones.   

73, Scott WA9WFA
On Apr 6, 2014, at 6:52 PM, Walt Hutchens  <waltah at earthlink.net>  wrote:


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