How to cut elongated holes in metal

[dougsr.874]

The last several kits that I have bought have the front mounting plate with the center holes to small and to close together...the holes need to be elongated about 4 mm...
problem is, how to do it....side cutting drill bits do NOT work...so far I have drilled another hole close by the original hole , then used a
Dremel tool to grind out the remainder....but this is VERY time consuming....Is there a tool that can be used effectively????

 

[SunkyWorks]

Hi Doug

The Pro's use "end mills"

2.2 Machine Tool Basics -- Mill Cutting Tools -- SMITHY GRANITE 3-in-1
https://www.youtube.com/watch?v=ckzK-LbeZmY

 

[HeadSmess]

unfortunately, if you get endmills... you then require another "pro's" tool... a milling machine.
(a "smithy" is not a pro's tool, but merely a combo lathe/mill for those hobbyists that have no space for both machines... basically, they dont do either job terribly well!)


what youre already doing is about it, other than filing.

its not like youre doing it every day, are you?



or are you?


can just try flattening the mount, if its the steel one im used to couple of whacks with a hammer usually does it.

 

[darwin]

Dremel type tool that cuts on the side of the bit, some are stone, others are metal. Drill will work too with a bit that cuts on the side.

 

[Slogger]

It ain't pleasant, but a small round file and some elbow grease will get you there, too.
And the price is right.

 

[Soquel Flyer]

I use a die grinder with a carbide bit -