1.75 drill bit

[Double D]

An all this time I thought reamers were to clean up nasty drilled holes.....

[Victor3]

I have encountered problems making slight enlargements to already existing holes; the drill seems to grab and try to cut off center until it has half a turn or so of drill in the hole.  Next time I do that, I will bore the hole to finish diameter at least a hole's depth before starting to drill.  Maybe that will calm things down.

 This can happen if the drill point angles are not both exactly the same or don't coincide with the C/L of the drill at the point. This causes one edge to do most of the work, pulling the end of the drill off center as it's cutting. You end up with an oversize hole too. The greater the chip load, the worse it gets.

 This effect isn't as bad when drilling solid stock because you've got the entire drill point engaged in the material, which tends to center the drill as pressure is applied to feed it into the workpiece.

[b. snipes]

I have been cautioned if high accuracy is needed to not use a pilot hole for a spade bit. I feel in this case, high level of accuracy (thundermugs) it is not in the cards. And the pilot hole will be not much larger than the web but large enough for a strong drill to go a foot or so. I suspect I will use a 5/16th pilot for the 1.750" spade. I think the inside of a piece of mechanical tube could chew a reamer up fairly well. Even though the cut of .20 to .25" is about right for the size it would be interesting. That stuff is pretty crusty inside. You want to bite clean steel.    related but not on topic sorry, I have found if you patch a golf ball in a 1.750 bore it works rather well. But then there is that pesky patch out there setting the grass on fire. I have some spade tips down from 1.75" and will give them a look.

[Cat Whisperer]

I have a number of mortars in 1.75" diameter - very smooth bores.  They DO work very well with patched golfballs.  If the patch is damp it keeps the bore clean too.
 
I haven't tried cylinder hones, but I've picked up one or two cheap at yard sales.