How do you make these holes?

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metalb00b00

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Joined
Jul 8, 2012
Messages
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Hi guys, I'm in the process of making my own front panel. I use a raw piece of 3 mm aluminum plate.
Just finished drilling all the holes for the components, but unable to proceed further because I don't know how to drill the oval shaped bracket mounting holes.

In case I messed up with the naming convention, here's a picture showing what I meant.

I measured the hole size from one of my equipment, and the size is 10 mm x 6 mm.

I practiced by drilling two intersecting (progressive drilling by changing the drill bit size from 1 mm to 6 mm) 6 mm holes on an unused piece, thinking that I would later scrape off the jagged edges with a thin rasp, then smooth it out to make that oval shape, but no luck. Drill bit repeatedly got caught in the intersection, and then slipped randomly to any direction. I'm using a hand drill BTW, not a fixed drill station, so.. perhaps this is why it didn't work??

Anyone knows another technique on how to make these holes flawlessly? I don't have a router, or punching machine. Just a hand drill and a complete set of drill bits with both imperial and metric unit diameter.
 

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By hand...your only hope is to drill one hole and then elongate it by filing. In the future, you should absolutely buy blank rack panels that already have those holes.
 
FWIW, the metal fabricators seem to call that hole an "oblong", and they are made with a special die on a punch press.

Bri

EDIT....I meant to say "obround", which is guess is a combo of oblong and round.
 
Use a punch to mark the centres of the left most and right most 6mm holes then drill them. Next get a small file ans file out the gap between the two by hand.

Cheers

Ian
 
Good idea Ian, but the distance from the center of the second hole you would have to drill and the edge of the first hole is only 1mm in a 6x10mm oblong...even with a drill press that's virtually impossible.
 
if you got a fast router:

I use these:
http://www.pferdusa.com/products/202a/index.html

they also have a range for finer use,
http://www.pferdusa.com/products/202e/index.html


they're for "deburring" metals, but more than often used for small machining/milling works. For making oval holes, or straightening edges, I find them perfect. :)

We have a metabo grinder motor, put in a drill stand, and with a small compound table (or a steady hand/piece of wood and some clamps), this makes a very versatile tool...

Keep them spinning,
Bert.

 
Do you need an oblong / obround hole to mount it in your rack?

Just a round hole in the right place should be good enough for DIY purposes.

Perhaps drill slightly larger than the bolt, to give yourself some wiggle room.

Stewart
 
zebra50 said:
Just a round hole in the right place should be good enough for DIY purposes.

Perhaps drill slightly larger than the bolt, to give yourself some wiggle room.

what he said - or go the DaveP route: drill and then hacksaw out from the side for a slotted mount. I like this too.


Mockup_zps9200eaa4.jpg


 
Thanks for the replies :)

I managed to make the oblong hole on my practice piece in the way I initially did at first (same as Ian's approach)
Result is acceptable. I just need to buy smaller metal files, both round and flat to make it close to perfect.
 

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MagnetoSound said:
zebra50 said:
Just a round hole in the right place should be good enough for DIY purposes.

Perhaps drill slightly larger than the bolt, to give yourself some wiggle room.

what he said - or go the DaveP route: drill and then hacksaw out from the side for a slotted mount. I like this too.


Mockup_zps9200eaa4.jpg

Rarely seen those on 1U panel size tho, but I will do it if after several tries, the oblong holes I make are less than 95% perfect.
On a positive note, I don't need to use a hacksaw because I have access to a CNC laser cutting machine.
 
metalb00b00 said:
Thanks for the replies :)

I managed to make the oblong hole on my practice piece in the way I initially did at first (same as Ian's approach)
Result is acceptable. I just need to buy smaller metal files, both round and flat to make it close to perfect.

With what size bit? I'm actually really surprised at this having worked...
 
Ptownkid said:
metalb00b00 said:
Thanks for the replies :)

I managed to make the oblong hole on my practice piece in the way I initially did at first (same as Ian's approach)
Result is acceptable. I just need to buy smaller metal files, both round and flat to make it close to perfect.

With what size bit? I'm actually really surprised at this having worked...

Progressive drilling by stepping up the bit size by 0.5 mm. I started with 2.5 mm (0.10"), and ended with 6 mm (0.236")
I also drilled the two intersecting holes at the same time.

I don't have the proper metal files, otherwise the oblong hole would have been perfect.

 
BTW, check this out:

http://www.hougen.com/punch_pro/punch_pro_index.html

The cordless version cost about $2,500+

I guess I would buy it if I make 19" enclosures for a living, haha ;D
 
Ptownkid said:
Good idea Ian, but the distance from the center of the second hole you would have to drill and the edge of the first hole is only 1mm in a 6x10mm oblong...even with a drill press that's virtually impossible.

In which case you can probably get away with just the two holes, one at each end, and some elbow grease and a small file in between.

Cheers

Ian
 
That's exactly what I was referring to...once the first hole is drilled with a 6mm bit, there's only 1mm from the edge of that hole to the center of the hole you now need to drill. I didn't even think it would be possible to drill hole number two...
 
MagnetoSound said:
or go the DaveP route: drill and then hacksaw out from the side for a slotted mount. I like this too.

Everything old is cut out to the edge like this.  Far easier than getting a hole correct. 

As said, you can also start two holes with small bits and progressively work up, but....why bother? 
 
metalb00b00 said:
Thanks for the replies :)

I managed to make the oblong hole on my practice piece in the way I initially did at first (same as Ian's approach)
Result is acceptable. I just need to buy smaller metal files, both round and flat to make it close to perfect.

A set of needle files is what you need.

Cheers

Ian
 
I use something like this...
FRESA_DE_TOPO_EM_4dc6b2d0e8a10.jpg


But I have a drill press and a cross table for that job, anyway they let you drill in overlapped holes, so may help you, not so expenssive as tungsten carbide burs, I boght a couple of them of 3mm and 4mm in about U$12 each, and here in my country is the same price as a regular bit of 6mm or 7mm. I also get for a similar price (U$12) something like those burs but HSS 6mm...

JS
 
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