How did I mess up this "crooked" drilling?

Bob Korves said:
Drilling holes is not a precision operation. Drills only remove metal. Drills do not go straight. Drills do not stay on the axis they start on. Drills do not drill a hole the diameter of the drill. Drills are only for removing metal. If you want the hole to be in a specific place, or to a specific diameter, or even better to the right diameter AND in the correct place, both at the same time(!), then you need to pay a lot more attention than just punching a hole with a drill. An under sized drill, then boring bar followed by a reamer, or a precision bored hole following a drill, are the best ways to get there.
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I should also mention the perverse, inverse laws of making holes in metal. Or wood, plastic or whatever. When I punch a quick hole in scrap metal, with a dull drill on a mediocre drill press, it usually comes out perfect. When I need a perfect hole, in an exact location, that really looks nice, on a fussy and important (to me) job that is 99% done, there is absolutely no way I am going to nail it...
:headache:
 
When I do mirco machining and specifically making small holes. I turn the work in one direction and also the drill bit (in the opposite direction). This method helps hole alignment and gets your cutting speed without just cranking up the headstock or drill chuck to crazy rpm’s…Dave.
 
Bob Korves said:
I like Dave's ideas here. I will even take it farther. Where possible and practical, change the design to use a commonly available size, without having to make a custom piece of tubing. Heaven knows that there are LOTS of options of off the shelf materials. Going even beyond that, start your search at your metal rack and box of drops.
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Yep. I know exactly how I'd make that part. Find a piece of pipe that I scrounged that was close, turn the outside, drill to close the right dimension, bore or ream to finish (depending on my needs), cut off the part and face it.

I frequently find various sizes of pipe at the dump. I used one to make spacers for my old horizontal mill. Now I know that spacers are supposed to be hardened and ground, but the ones I made work for me.
 
chips&more said:
When I do mirco machining and specifically making small holes. I turn the work in one direction and also the drill bit (in the opposite direction). This method helps hole alignment and gets your cutting speed without just cranking up the headstock or drill chuck to crazy rpm’s…Dave.
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Live tooling?
 
One thing I don't think was mentioned yet is facing the end of your stock off before drilling. I know I had that bite me when starting out. I'd center drill and then drill but it could be misdirected early if the end of my project was not faced square first.
 
One thing you can try if they're not super deep hols is some stubby drill bits to minimize flex I got a set at a pretty good price from drill hog on ebay they say they're usa made with lifetime warranty I like mine so far I got a stubby set and silver and Deming set
 
Interesting discussion.

I've always wondered how they got long straight holes in gun barrels.

I kinda figured they drilled the deep hole, then turned the OD of the round stock "about" the hole!
 
jmarkwolf said:
I kinda figured they drilled the deep hole, then turned the OD of the round stock "about" the hole!
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They do.
But just getting a hole with in .030 in 20-28 inches is quite an accomplishment.
The Green Mountain barrel blanks I have gotten are .006-.010 off on one end and usually .030+ off on the other end. Not bad for drilling 30" per minute.
 
Go buy The Model,Engineer's Workshop Manual buy G H Thomas from Tee Publishing. Best general machining book EVER. There is a whole chapter dedicated to this. Another on parting off. He wrote for Model Engineer, but the info is gold for anyone who turns handles.

Drills cut best when only the outer part of the flute is working, so you start with a small dia. and use several drills of increasing size to drill your hole.

Drill 2 diameters deep, the retract and clear the chips

Buy good USA (UK, German) made drills and keep them good by using reasonable speeds and cutting oil and don't drill concrete with them.
 
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