how to grind bolt head to proper diameter?

[MaxPower]

BACKGROUND (not necessary to know):

My bike's an '88 EX500.

On the back half of the left handlebar's control housing is a tab that plugs into a hole in the handlebar. This keeps the control housing from rotating. The tab has broken off and I need to replace it to keep the housing stationary.

I'm going to insert a bolt into the housing where the tab used to be. The bolt's head will plug into the hole on the handlebar. The hole is about 3mm in diameter.

I haven't been able to find a bolt with the proper-sized head diameter (it needs to be accurate or this repair won't work). I'm going to use a mild steel hex-head bolt... but the head of the bolt I'm going to use is just slightly larger than the hole. I need to grind it down about 0.5mm in diameter.

MY QUESTION (finally):

How can I grind the head of a mild steel hex-head bolt down about 0.5mm in diameter? (Or, if you read the above, do you have any other advice?)

Thanks!

[oreo_n2]

bench grinder or right angle grinder or dremel????

or am i misunderstanding the complexity of the problem?

[MaxPower]

Hmm... I was afraid you'd say that! I don't have any experience with those machines. I was hoping for a more low-tech way to do it. Do you think a metal file would work? Or would that be too slow?

[beet]

takes a long time if you can fit im not sure wtf your talking bout
i think a bench grinders what your looking for or ask i think i might have what your looking for in my invatory of parts

[TLRMan]

you need a 1/2 of a mm?

Dude, that's only .020" in diameter..do you mean 5mm? >.1969?
And yes I have the grinder to do it...you just gotta get it to me with the correct dimensions...

[oreo_n2]

after the holidays give me a shout, i could stop by with my dremel and tap set?
it sounds like the problem could be solved pretty easily wth the right tool.