[How do I?] Center On A Part To Drill A Hole

New Hermes Engraving machines offered a small and affordable self centering vice for their machines. it wouldn't hurt to check them out.
 
All you need is a soft 5c step collet. Machine the shape in it and it will repeat part after part. Loading time is seconds. Cost is cheap
less than 30 dollars. I have done thousands of parts that way.
jimsehr
 
Seems like that people are forgetting that the part width is variable 7/16" to 1/2". The Grizzly looks like an off-the-shelf solution to me. Amortize the cost over thousands of parts. My only concern would be the ability to hold +/- 0.005.
Quite range of prices for that vice :) :
https://www.grizzly.com/products/2-Mini-Self-Centering-Vise/T10254
http://www.amazon.com/Grizzly-H7576-Precision-Self-Centering-Vise/dp/B000E34BT4
http://www.tequipment.net/Mark10G1070.html?Source=googleshopping&gclid=CJSRk8CCj8QCFZI0aQod6zIAmQ

Lots of alternative self-centering vices out there. Pneumatic or hydraulic may be a more time/cost effective for large volume production.

Ken
 
How about bin sorting your parts in 010" increments (.490-.500", .480"-.490", etc.)? For your .490" -.500" bin, set your drill .245" from the fixed edge of your vise. All parts in that bin should be within +/- .005" of the true center, drill bit wander notwithstanding. Move the center to .490" from the fixed edge and drill the .480" - .490" parts.

It adds an extra step but when you balance it against making a centering fixture or spending the $160 plus for a centering vise, it may be your best option.
 
Thank you all for the ideas so far.
The cost of a self centering vice or building a fixture is not an issue, there is several hundred in the budget for fixturing if needed. Ease of use for an unskilled operator is paramount. A lever release, spring loaded device is probably best.

Outside of the box thinking is welcome!
.
.
.
 
You might consider a jig that's a variation on that used by woodworkers to drill holes centered on the narrow edge of a door.

For your application a flat piece of steel with two hardened pins sticking up about an inch apart (possibly less) with a 1/8" hole exactly mid way between them. Position this on the drill press table so the central hole is aligned with the 1/8" drill and clamp it in place. Inserting a work piece between the two pins and turning it so it presses against both pins will position the drill at the mid point of the work's width. You might want to add a quick acting clamp to hold the work in place once it is positioned with the aid described below.

A way of setting the end distance would be a round piece of the appropriate diameter on the drill 1/2" above the drill point, held in place with a set screw. A small right angle block could then be used to push against the work end until it contacts this round piece to set the drill position from the end of the work piece.

Positioning accuracy would need to be evaluated by experiment. I haven't built or tried this, just a wild scheme that came to mind when I saw the problem description.

John
 
gaston said:
good luck holding .ooo5 in any drill press I've used!!
Click to expand...
Should be possible with a bushing for the drill bit.
GadgetBuilder said:
You might consider a jig that's a variation on that used by woodworkers to drill holes centered on the narrow edge of a door.

For your application a flat piece of steel with two hardened pins sticking up about an inch apart (possibly less) with a 1/8" hole exactly mid way between them. Position this on the drill press table so the central hole is aligned with the 1/8" drill and clamp it in place. Inserting a work piece between the two pins and turning it so it presses against both pins will position the drill at the mid point of the work's width. You might want to add a quick acting clamp to hold the work in place once it is positioned with the aid described below.

A way of setting the end distance would be a round piece of the appropriate diameter on the drill 1/2" above the drill point, held in place with a set screw. A small right angle block could then be used to push against the work end until it contacts this round piece to set the drill position from the end of the work piece.

Positioning accuracy would need to be evaluated by experiment. I haven't built or tried this, just a wild scheme that came to mind when I saw the problem description.

John
Click to expand...
Use two of these pivoting on shafts into the base of the device. Connect the two with a linkage and use a lever, springs, and an over-center mechanism to lock/unlock. You would place the part between the pins, push it up against the stop (you could use a magnet to hold it there or tilt the whole assembly and use gravity). The stop could have a slot to receive the end of the part and a bushing for the drill bit.
 
*IF* the parts are uniform standard widths (not each part being oddball width) Mill the different width slots in a piece of aluminum, grab that in a vice, drill the hole the correct distance from the end. You end up with a stepped slot, hole in the right place. Add a work stop and have at it. The part sits in the proper sized slot, hit the workstop, drill hole. You could screw a strap over the top of the slot sideways to prevent the workpiece jumping out. Slide in part, squirt cutting oil, drill, remove, repeat ad nauseum.
If the parts are all unique widths, a lever activated self centering vise would be quick, pneumatic with a foot pedal even faster, but *WATCH THOSE FINGERS!*
 
You must log in or register to reply here.
Back
Top