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green
08-03-2011, 10:53 AM
Hi to all. This is my first post. I have a cnc router and need to drill a .018 hole in a steel rod that already has a .015 hole. How do I set up the rod so that it's perfectly perpendicular to the drill? I have a toolmakers vise.

Also, any advice on how to prevent the drill from breaking will be appreciated.

I don't have a lathe, nor a high speed precision drill--only a cnc router with a router that spins at 18,000 rmp and has a variable speed control.

As to the drill, I need advice on that, too. I currently have a few carbide micro drills used for pcb work.

By the way, I am looking for a lathe. I am simply waiting for a good deal to show up in my area.

thanks
tc

lynnl
08-03-2011, 12:20 PM
Not sure I can provide answers. But I can anticipate several issues that will likely need clarification:
1. How big is this rod? Length/dia. (i.e. in relation to your cnc router set up & vise)
2. Is this to be a new hole, in addition to the existing hole? or just an enlargement of the old hole?
3. What kind of steel is the rod? Some are notorious for work hardening.
4. What tools do you have for checking alignment? Test indicator? Vee block for holding the rod?
5. Define "perfectly perpendicular." I'm guessing you're meaning "as good as I can get it" or something like that.
6. Also, is this hole to be drilled axially? Am assuming so, but that's not absolutely clear.

philbur
08-03-2011, 12:30 PM
Probably best if you give details of the functional requirements for the rod then somebody will pop up and give you an appropriate process. Otherwise there are a multitude of questions that you probably cannot answer.


Phil:)

vincemulhollon
08-03-2011, 12:33 PM
Is the word you're looking for "concentric" as opposed to "perpendicular"?

Picture being worth a thousand words:

http://www.dragonworks.info/CAD-CAM-CNC/Micro-Mill%20CNC/XY%20axis/pictures/DSC00070.JPG

Part of

http://www.dragonworks.info/CAD-CAM-CNC/Micro-Mill%20CNC/XY%20axis/micromill_cnc%20X%20amd%20Y.htm

Also drills don't much like eating 3 thousandths... Its not gonna end up round and its not gonna end up concentric. A reamer would be nice, but thats a mighty small diameter. I'm just saying it's gonna be rough. Also your 3 thousandths nominal might increase by 5 or 10 if the drill is even microscopically out of alignment. The point being a drill is the wrong tool for working to thousandths. Its too small for a hone, right?

I know this is almost legendary bodging, but can you safely enlarge that hole by pushing a properly sized round hardened ball thru the hole a couple times, assuming its a thru hole not blind hole?

vincemulhollon
08-03-2011, 12:46 PM
... a .018 hole in a steel rod ...

Check out a wire gauge chart on google. that is a about a number 25 wire gauge hole.

Find a piece of 25 gauge music wire, sharpen an end to fit thru, and swage it thru to stretch the hole? Warning it might take enough force to deform the entire rod or damage however its being held.

Oldbrock
08-03-2011, 01:33 PM
And your area is?

achtanelion
08-03-2011, 01:47 PM
Or, take a piece of 25Ga music wire, grind off a little less than half, and use it as a reamer. They're called D-bits and I use them all the time for odd sizes.

J

green
08-03-2011, 08:59 PM
I am impressed with the various replies and, accordingly, they've helped me sort a few things out.

1. I've ruled out a drill-- it'll probably break, assuming that I could line it up perfectly.
2. I like the idea of music wire , pointed, and pulled through. I have some 600 grit lapping compound which will let me use a smaller wire and work my way up to the size.

3. Now I need to figure out how to widen the slot that follows the hole.

see pic. It's easier than trying to explain it.



thanks again for the wonderful input.

Oops. How do I upload a pic. I don't see an attachment icon.
tc

Black_Moons
08-03-2011, 09:06 PM
To awnser the origional question, I would put a indicator into the spindle, and a straight rod into the hole

Go to one side of the rod, move the Z up and down, tilt workpeice untill no change is observed.

To go 90 degrees of that side of the rod, move Z up and down, tilt workpeice untill no change is observed.
Recheck origional size of rod to ensure it did'nt shift while tilting workpeice. Repeat as needed.

Then, Rotate the indicator around the rod by spining the spindle by hand. Move X/Y table untill indicator reads 0 reading

Congradulations, Your spinde is is now centered over the hole exactly, and aligned with the axis of the hole exactly*.

*As exact as how good your indicator is multiplyed by how far long Z you swept, Devided by any bend in your test rod.