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mklotz
08-21-2007, 03:30 PM
It seems that, whenever I get the prick punch located just so, I accidentally nudge it out of position while reaching for the hammer I've inevitably forgotten to lay close to hand.

So, I made a prick punch that has a built-in hammer.

http://i81.photobucket.com/albums/j234/mklotz/tools/PRICK.jpg (http://s81.photobucket.com/user/mklotz/media/tools/PRICK.jpg.html)

The steel slug rides freely on the rod and is dropped, slidehammer-fashion, onto the steel plate pinned to the shaft to drive the prick punch into the work. The punch itself is made from an index hole punch rescued from an old mechanical teletype. The brass screw at the end hides a pocket to store punches and also serves to keep the hammer on the rod.

Bill Pace
08-21-2007, 03:47 PM
How simple!, ----just reversing the old reliable sliding hammer dent puller thats been around forever

nuther good-un, Marv

pgmrdan
08-21-2007, 03:49 PM
Marv, you make some of the neatest stuff!

BadDog
08-21-2007, 04:11 PM
Very nice again.

Man, working at small scale is SO much different than large scale. Sunday I had to make a tiny screwdriver for my son. He was working on his Nintendo DS (little hand held folding game system) and it has these odd 3 blade tiny screws. Like a phillips, but 3 blades. Found them on line, but nothing locally that he could get on the weekend (or so it seemed). So I made one out of a 1/16" ejector pin with vacume tube rubber handle. Worked perfectly and held up to repeated use showing no wear, but WOW working at that scale will wreck your nerves (or mine at least).

IOWOLF
08-21-2007, 04:31 PM
Nicely done.:)

mklotz
08-21-2007, 04:42 PM
Very nice again.

Man, working at small scale is SO much different than large scale. Sunday I had to make a tiny screwdriver for my son. He was working on his Nintendo DS (little hand held folding game system) and it has these odd 3 blade tiny screws. Like a phillips, but 3 blades. Found them on line, but nothing locally that he could get on the weekend (or so it seemed). So I made one out of a 1/16" ejector pin with vacume tube rubber handle. Worked perfectly and held up to repeated use showing no wear, but WOW working at that scale will wreck your nerves (or mine at least).

One quickly learns that miniature work is ALL about workholding. If the parts are tiny enough, most of the standard shop equipment is just too oversized to be directly useful. One quickly becomes expert at designing all sorts of gadgets to bridge the interface between the tiny part and the available tooling.

It helps to learn to be able to do things blindly. For instance, the PMR model of the treadle-powered wood lathe requires you to cut a four edge spur center into the end of a taper pin that is less than 0.125" OD. Even with magnifiers, you can't really see what you're doing. After a bunch of practice pieces to work out the exact settings, I finally did it using only the dials for reference.
(By dials, I mean the three dial indicators permanently attached to the Unimat axes.)

BadDog
08-21-2007, 05:02 PM
It also helps to have the right tools, like your micro mill. I made the 1/16" screw driver, with final working diameter of 0.050, using 5C collet blocks (for indexing) in the Bridgeport mill with a very carefully dressed medium-fine dremel grinding stone held in R8 and a 10x loupe for setting the location (edge finding). Just as you suggest, during the operation, there is NO WAY I could see the cut. I just had to trust the dials and use the color of barely visible tip (under 500W lights) to gage feed rate and DOC (about 0.005 per pass on each flute). My mill has almost as much back lash as the final width of this thing. :D Man, using the Bridgeport on something that size felt like using a semi tractor to back in a 4 foot lawn cart.

But it was worth it when I showed my son who got big eyes and jaw hit the floor. He's now 20, so he tends toward the "I've been around the block and there's not much more you can teach me." view. My screw driver was actually smaller and nicer than the jeweler screw driver he was using on other parts (phillips). Then I gave him the loop to look at it up close and compare, and his jaw dropped again. You could see the rough(er) finish of the (admittedly cheap, but they work) Craftsman jeweler screwdrivers, and the invisible to the naked eye deviation in width of it's "blades". Mine looked "perfect" even under 10x. :D

quasi
08-21-2007, 06:51 PM
I can't tell you how many times I could have used this tool. Thankyou for sharing this invention.

Al Messer
08-21-2007, 08:57 PM
Don't they still make the Starret spring loaded punches? I obtained mine about 18 years ago and use it constantly when marking out.

mklotz
08-22-2007, 11:00 AM
Don't they still make the Starret spring loaded punches? I obtained mine about 18 years ago and use it constantly when marking out.

Maybe it's just my technique but I find the spring-loaded punches hard to control with good precision. With the slide hammer, there's no need to apply force to the punch to make the mark - force that can easily displace the mark.

TGTool
08-22-2007, 11:57 AM
I like the slide hammer punch, though a standard punch and an automatic one have always worked for me.

I was taught to find the intersection of the layout lines by feel. That is, with two intersecting scribed lines, get the point of the punch in the groove of one line, then draw it along until you feel it click into the the intersection. Raise it upright and hit it. That's been a more useful technique as my eyes have gotten less acute than they once were.