Reamer for match drilling large holes?

[ymc9]

I found my match-drilled #12 holes don't look too good (or consistent). I heard that using a reamer will result in more precise holes, but I've never tried one. Is it a good idea to use reamer for match drilling?

 

[Brantel]

I use a reamer any time I can. They are the bomb!

 

[ymc9]

I use a reamer any time I can. They are the bomb!

Cool! I'm thinking of getting one from Cleaveland tools. They have 3/16 and 0.1880 (which is closer to the #12 drill size). Vans wants me to match drill with #12, so I guess I should go with 0.1880 then?

 

[Stevea]

A #12 drill is 0.01890" diameter. A 3/16 drill is 0.1875" diameter.

Search the web for "drill chart".......they can be downloaded for free. It should have hole sizes for numbered drills (1-60), fractional drills, and lettered drills. (Who knew there were so many drill sizes? ) The chart will definitely come in handy.

Also, if you are going to ream to final size, you will have to drill an undersized hole.....typically 1 drill size smaller for the hole sizes we're dealing with, and then ream the hole to final size.

Building an RV....at least the 3/4/6 where ALL the holes had to be drilled....kind of like getting a PhD in hole drilling/reaming, while picking up a Masters Degree in de-burring.

 

[ymc9]

A #12 drill is 0.01890" diameter. A 3/16 drill is 0.1875" diameter.

Search the web for "drill chart".......they can be downloaded for free. It should have hole sizes for numbered drills (1-60), fractional drills, and lettered drills. (Who knew there were so many drill sizes? ) The chart will definitely come in handy.

Also, if you are going to ream to final size, you will have to drill an undersized hole.....typically 1 drill size smaller for the hole sizes we're dealing with, and then ream the hole to final size.

Building an RV....at least the 3/4/6 where ALL the holes had to be drilled....kind of like getting a PhD in hole drilling/reaming, while picking up a Masters Degree in de-burring.

Good advice! I'll print one and hang it straight above my workbench. Even though there are already so many sizes, tool makers sometimes give sizes that are neither fraction nor numbered

 

[Dr_Dave_MT]

Good advice! I'll print one and hang it straight above my workbench. Even though there are already so many sizes, tool makers sometimes give sizes that are neither fraction nor numbered

You can buy a #12 reamer. as a matter of fact I have an extra if you want., think I have about three of them. For the "final drill" size of a 3/32 they want ya to use a #40 drill, Just use a #40 reamer, for 1/8" they have ya "final drill" to a #30 drill, just use a #30 reamer. Pan American Tool company , KFFL

 

[Stevea]

Good advice! I'll print one and hang it straight above my workbench. Even though there are already so many sizes, tool makers sometimes give sizes that are neither fraction nor numbered

True. Didn’t mention there are undersized and oversized reamers. For example a #12- or #12+ where the + or - denote some offset from the nominal #12 dimension. The good news is, you shouldn’t have to go to those sizes to build an RV airframe.