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Material for center punch

68rscamaro

Plastic
Joined
Jan 27, 2010
Location
Idaho Falls
I'm a rookie/hobby machinist and I'd like to make myself a couple of center punches. Is there a material that's easily hardened that will hold up? A guy at work suggested rebar.....isn't it already hardened? would it work? 1144 maybe?
Thanks in advance
 
depending on what OD you are after

an L shaped tire iron is made of carbon steel, easily annealed so you can form it as you like, then reheat and quench in oil, then temper.

smaller diameter?
use the crank extension from the undercar jacks, some of which are about 3/8 inch stock
or the torsion rod springs from under trunk lids on some cars, or the hood support rods are also carbon steel

you get to looking around there are lots of sources for suitable material for punch/ chisel, drill bit, screwdriver shaft, prybars, etc. fabrication.

bob g
 
I sharpen a point on broken taps to use as center punches. Works pretty good. If you are just starting out you will probably get some broken taps soon.
 
I sharpen a point on broken taps to use as center punches. Works pretty good. If you are just starting out you will probably get some broken taps soon.
Lol yeah I already have a collection of broken taps!;)
A guy a work has a center punch that one of his machinist buddies made for him.....I figured that would be a simple enough project but he doesn't know anything about it. I would say it's maybe 3/8 diameter 4-5" long.
I may try to find some old hood supports as suggested.

Anything else? Something I could just buy like 10' of raw material to just play around with. I know once I get it right several buddies are going to want one of their own
 
I have a prick punch and a center punch set that were made from 3/8 dia Danly ball lock die punches salvage from an old die. These work great if you can find em. 3/8 dia O-1 drill rod should work well and is easy find and to flame harden. You should be able to flame harden the business end with a Mapp or propane torch. Turn the end down to 3/16 or so and leave a generous shoulder fillet just enough to "look right" and your ready to go.
 
Take warning that using taps, die punches, ejector pins, etc for punches is dangerous. They are way too hard to be striking with a hammer. Chipping and shattering tools can penetrate deeply.

That said, I use all of the above for punches, although I usually anneal the end that I strike.
 
Take warning that using taps, die punches, ejector pins, etc for punches is dangerous. They are way too hard to be striking with a hammer. Chipping and shattering tools can penetrate deeply.

That said, I use all of the above for punches, although I usually anneal the end that I strike.
What he said, bad practice:willy_nilly:
 
Although entirely possible to find suitable old junk, you can't beat the availability and easy to harden aspect of 01 drill rod. I torch harden the business end and leave the rest soft. As it mushrooms from bashing it with a hammer, grind that off.

I made one once from a big rat tail file. I beat on the end that was nearest the tang, but finally broke it anyway. As well said above, too hard.


If S7 drill rod available, even better.

John Oder
 
A friend gave me some 3/8 bolts designed to be driven into steel beams or concrete. They just need the point sharpened a little bit.
Bill D.
 
Thanks for all the replies.....Much appreciated.
I just ordered some of the 01 drill rod so I'll give it a shot
Can anybody tell me the proper procedue to harden after the machining is done?
Heat it to red and dip in oil? water?
 
Heat to cherry red,quench in oil,Shine up with emory paper(take the black off) hold in medium flame an inch and a half back from pointed end and watch the color.Hold the part with tongs (or pliers) on the end that you will strke with a hammer when using it.A nice "straw" color is what you are trying to achieve on the end you want hard, so concentrate most of the heat on the part above the pointed end and watch as the color starts to turn from straw to dark straw/brown to blue,It (the blue color) will continue up the part quickly toward your pointed end. When the end begins a light straw color quickly quench the part in oil, and presto!,you have your new hardened tool.This technique will take some practice to achieve perfect results,but once you learn it, it's like riding a bike.
Good luck!

PS. A nice "straw color" will be about 58 to 60 Rockwell C scale.

PS again. Water will work for quenching but it is considered that it may make tool more brittle.

PS one more time: while annealing, watch the color travel toward the end. You want to catch it while it is straw color,(before it turns blue) If you let it turn blue,you have failed and it won't be as hard as it needs to be.Watch the strw/brown color and just before it reaches the end that you want hard,drop it in your quench to stop the annealing. Clear as mud?
 
Well, O-1 means it's Oil hardening; if it were Water hardening it would be named W-1. Logical, wot?

Inexperienced individuals should use a propane torch for this sort of heating... Have a ceramic magnet (as opposed to rubber magnet) handy nearby, hanging from a wire fixed to whatever.

Heat the business end of the punch until it is dull red in subdued light and hold it against the magnet. If attracted remove from magnet and keep heating until the magnet is no longer attracted to the punch.

Immerse punch vertically into a can/bucket of very warm water and slosh around until cool.

Clean and polish the business end and re-heat with a small and gentle flame from the middle of the punch, until the sharp end turns straw yellow. Stop heating and let air cool. Sharpen on pedestal grinder by twirling the punch so as to get longitudinal grind marks.

Cool often in water during grinding so as not to overheat and soften the point.

Welcome to the wonderfully liberating world of do-it-yourself TOOLMAKING!

Arminius
 
Thanks for the quick response. I wish I knew everything that some of you guys do!!
The O-1 makes sense now that you say that. I thought it was a zero :)
The only thing that has me confused now is Armenius says the drill rod is oil hardening but your telling me to dip in water?
 
I guess I just got lucky. I snagged a full, brand new set of No.264 Starrett center punches in the newer-style plastic round case for a whopping $7. :D That was from a local guy who works for Starrett and was advertising some tools on Craigslist. He did have a good explanation of how he got them so cheap. The knurled square shanks are nice....no roll.

I also got a pack of 5 No.117AA off of Ebay for about $5 plus shipping. Factory seconds with the lightest little touch of rust. These are the round shank, 3" long with a 1/16"tip, and I use them exclusively for reversing out those over-tightened flathead screws used in insert toolholders. Works perfect!
 
the process is to heat to cherry red, and then dip in oil
this is the hardening process, the result of which is the piece
will be hard as hell, too hard for a tool such as a punch.

the second process is tempering, as mentioned emery or sand the tip to a bright finish, do so back about 2 inches to give you some room to play. then slowly heat back about 2 inches and watch carefully the shiney tip surface, it will start to turn a very light yellow, then full yellow, then straw color, at this point immediately drop into water

the use of water is to stop the tempering at this specific point, the temperature is likely something on the order of 400-450 degree's F
so it is not that hot and water will not hurt it, water is just faster at stopping the heat flow than oil is.

then to be on the safe side, heat the hammer end until it is full dark blue, almost black using the same process, and just let it air cool
or you can drop it in water as well, this will just about fully soften the working end so that it will mushroom rather than splinter.

of course you will be using safety glasses everytime you use this or any other tool right?

:)

bob g
 
You guys here are a weath of knowlege. Thank you!!
I'm excited to give it a try. This will be my first attempt at hardening and tempering so wish me luck! Is one certain oil better then another? Which would you reccommend?
 
i will probably get kicked for this, but i use "used" motor oil from
a diesel engine, the really black stuff has more carbon in it.

don't know if that helps anything or not, but i got lots of it on hand.

some folks like ATF, some use hydraulic, some use vegetable oils
and i am sure there is even a special made for this purpose oil as well.

i bet for your purposes there is not a nickels worth of difference between one or another. at least not until you get some experience making some tools, working with them, and then reworking to tweak things to your liking.


bob g
 








 
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