How would I drill a hole in a hardened vee block?

[auto.pilot]

The title says it all... Would like to drill a hole through the vee, so it can be used as a drill centering jig for cross drilling round stock. Plan is to put the round stock under the vee, then clamp both in a vice for use on a drill press. Ideally, the hole in the vee would be large enough to accommadate drill bushings with various IDs.

http://books.google.com/books?id=NN...d=0CDoQ6AEwAA#v=onepage&q=Cross drill&f=false

If anyone makes such a device, please let me know, because I can't find one, and I'm nearly certain I can't make one. Better yet, take this 60 year old idea, make some yourself and sell them (you have your first customer right here).

 

[JBrentMac]

First of all, I wouldn't recomend this. There are plenty of good ways to set-up to drill cross holes in round stock. You could even make your own vee block with the needed hole included. But if you insist on cotting up a perfectly good vee block that is hardened you're going to need carbide. If the V-block is case hard then once you get through the case(probably .04-.06 deep) then the softer inside shouldn't be too tough to get though until you reach the case on the other side. If it is hard all the way through... well you're in for some WORK!
I would use a carbide endmill and set the quill stop just ast you touch the surface. Increment it down about .01 at a time and pull hard until you've broke through (at least the hard part). This will keep the chatter down to a minimum. Make sure you keep the holle you a makeing good and cleanr of chips(use compressed air if you've got it).
This method also works for drilling out broken taps, drills, and dowels.

 

[Allan]

Auto Pilot, funny you should ask.
5 minutes ago I was just reading an older issue of the British publication, Model Engineers' Workshop. In it there is an article by Alex du Pre that shows how to build a cross drilling jig. The basic idea is make your own V block and drill bushings to fit in an overarm to accomodate various sized drill bits. To cut the V he uses a slitting saw and finishes it with a fly cutter. I don't think he hardens it but I guess you could case harden it depending on how much use you anticipate. The dimensions are metric but should be no problem to convert it to Imperial if you prefer. The issue is April 2009 (No 149). It looks quite versatile and fairly easy to make one, especially if you have a mill.

Al

 

[Ray C]

If you must use a hardened V-block, annealing it beforehand would be one way of doing it but, that won't be easy. Assuming it's tool steel, it will need to be held at about 600-800F for about an hour and gradually cooled in the oven. That will knock the hardening out but it'll still be hard to drill and suspect you'll need carbide tooling. Then, there's the issue of slight distortion and re-treating it.

I drill/tap holes in shafts 1-2 times a month and just use a centering bit to get the hole started.

 

[auto.pilot]

Thanks for the replies. I should clarify that my work is rather small. Generally, drilling 1/4 inch holes through 1/2 inch stock. Any off center hole is very obvious. Would appreciate any thoughts on the best method.

 

[wawoodman]

Have you tried one of these?

http://www.lathemaster.com/ROUNDBARCENTERFINDER.htm

 

[Ray C]

What kind of equpment are you working with, drill presses, mills etc? Are you drilling perpendicular or oblique to the workpiece? Drilling all the way through the shaft of just a set screw?

Generally speaking, I fixture the piece in the mill vise, find the sides then move to center (i.e. subtract side distances and divide by 2) and use a centering bit to start the hole. Finish with a regular drill bit. If the desired hole is large in diameter, first drill a smaller hole (about 1/3 final diameter) to pilot the second. Make sure the bits are evenly sharpened. If you're not getting curlies out of both flutes, the bit is either or both dull or unevenly pointed; thus, it will wander. Although I've never had to do this, when you start your center hole, make a little mark where the tip will hit and possibly try grinding (or milling) a small flat spot on the workpiece. -And of course, the workpiece, vise setup etc must be trammed-up square.


Ray


EDIT: meant to say oblique instead of parallel... miswording fixed.

Thanks for the replies. I should clarify that my work is rather small. Generally, drilling 1/4 inch holes through 1/2 inch stock. Any off center hole is very obvious. Would appreciate any thoughts on the best method.

 

[bushwacker]

What I tend to do if I have a few holes to drill in similar sized material is to make a small block to accept the stock with a nice fit and then keeping the stock hole horizontal drill a hole of the required size horizontal to it through the block.

If you need to have the holes at the same position in evey-one you could even drill the horizontal hole blind to the corect depth so that the horizontal hole will be in the same position every time.

I was watching a Tubal Cain video on utube a day or two ago and there is one on there with diferent sized inserts that are used for different sized stock and different sized holes. I have made a couple of these at work to do just that and was pleased to see that they are quite a common drilling jig in America aswell as here in the UK.

I hope all of that makes sense to you.

 

[rgray]

I would recomend not drilling the hardened block and just making one.
I got the idea from a machining web site (don't remember where) and the guy made his v-block out of aluminum.
He made his with a mill and made a top plate that recieved the hardened bushing (whitch he made) and it also flipped over to hold smaller diameters.

I made mine from steel (on a shaper) it has a 120 degree V. I made two so I would have one for support on longer work.
The top plate is made from a chevy 350 crankshaft counterweight and the v-blocks are made from 7/8" thick grader bit(had to go in the wood stove and get sofened before drilled).
I made my drill bushings from o-1 tool steel the black ones are hardened and the others are undrilled extras for sizes I don't know I need yet.
I use it with the drill press. Regular sizes I drill are 3/8,1/2,5/8,3/4,&1" (making boring bars from 1144)

The other two QCTP's are for center drilling on the lathe. Someone on this site made a real nice one that went into the large boring tool holder...I made a quick one using the chuck and shaft from a cordless drill who's batteries died. I machined bronze bushings and stepped the shaft to 3/8 & 1/2" then attach a cordless (or corded) drill and center drill using the cross feed or compound. Works better than it sounds like it would.

That got me thinking Why not have the power unit in the quick change. So I built the aluminum dovetail and installed the innerds from a cordless LI batteried drill whos batteries had gone bad. It has one way clutching that
is handy as it keeps the drill chuck from turning when not powered so it can eisily be tightened and loosened.
But can't be used as a tap starter that way(cant have everything I guess).
It was a 12 volt drill And I use a motorcycle battery to power it. I juut recently made it so still crude with the switch hanging on the wires and wire nuts.....this drill has .002 TIR so not to bad.
Was my first dovetail cut (did it on shaper).
Still unfinished as it needs a depth stop.
also thinking of using it with some kind of slide table or removed crossfeed or compound...then mounting a 5C spin index on center and on a pivot to do holes at 45 degree and into the shaft end also. Mounting it all on a heavy plate....freeing up the lathe.
View attachment 44493View attachment 44492

 

[george wilson]

I bought one of those plated steel"swivel fork" things. But,it looked too cheap to be very accurate. I just lightly make a teeny flat spot on a round piece in the mill,then drill its center with a center bit. Good eyes and practice will get you quite close. If more serious,the edge finder can be used,etc..