how much bigger does a drill bit drill?

Read your original post. We have no idea what you are making or what it will be used for. Only a rod to push into a 3/16" hole. Some things want to be put together pretty much permanently and resist becoming loose. Others want to be relatively easy to take apart. We need at least a feel for what you are making, even if the actual intended use is highly classified... ;)
 
I am sure I could bore a small hole with a small boring bar in a small lathe or mill, but the real question is if I could get the press fit right...

Edit: Just need a Moore jig borer... or jig grinder... :cool:
 
Bob Korves said:
I am sure I could bore a small hole with a small boring bar in a small lathe or mill, but the real question is if I could get the press fit right...

Edit: Just need a Moore jig borer... or jig grinder... :cool:
Click to expand...

I just turned a shank for a tool I'm making on my sherline lathe to .3750 on the dot, over the entire length of the shank... seeing as how boring is exactly the same operation im going to go ahead and say that you could in fact get the press fit right...
 
Bob Korves said:
I am sure I could bore a small hole with a small boring bar in a small lathe or mill, but the real question is if I could get the press fit right...

Edit: Just need a Moore jig borer... or jig grinder... :cool:
Click to expand...

A Sherline lathe has very precise leadscrews and their handwheels are very accurate. Dial in half a thou, take a thou off the diameter. With the right tools, cutting to tight tolerances on a Sherline is pretty simple because what you dial in is pretty much what you get.
 
Boring comments aside, maybe the OP needs some guidance on what constitutes a light/medium/heavy press fit? (probably depends on materials involved also, right?)

I seem to recall pressing 0.125" dia steel dowel pins into 0.250" aluminum plate and using a reamer that was 0.005" undersize for a heavy press fit. It's been decades though and I've forgotten, plus I might've just been guessing back then -- so it would be good to know for future projects!
 
Rcdizy said:
The #13 was too loose still, Size smaller too tight.

The rod is excactly .1875

So in a perfect world, what reamer?

Would locktight work in this type of application?
Click to expand...

Reamer size already suggested in this post.

Wreck™Wreck said:
Excellent question Dr. Suess, .1865
Click to expand...

The lock tight (or super glue) should salvage the situation, choose the right one.
 
Dr_Romeo_Chaire said:
Boring comments aside, maybe the OP needs some guidance on what constitutes a light/medium/heavy press fit? (probably depends on materials involved also, right?)

I seem to recall pressing 0.125" dia steel dowel pins into 0.250" aluminum plate and using a reamer that was 0.005" undersize for a heavy press fit. It's been decades though and I've forgotten, plus I might've just been guessing back then -- so it would be good to know for future projects!
Click to expand...

Fits are a huge discussion that cannot even begin until the OP gives us an idea of what the application is.
 
To respond to the title question, how a drilled hole turns out is a function of several factors not the least of which is the quality and grind on the drill bit. It is not predictable. It might even be possible to end up with a hole smaller than the drill.
 
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