In a thread a few days ago, I mentioned the use of a repurposed cold plane bit as a center punch. The fat tungsten carbide tip makes a very durable implement, and one that can put a punch mark in hard metals without losing its sharpness. I had lost the one I'd carried for the last 20 years, and spoke of ordering a replacement and a spare.
Below are some photos of the bits that arrived today. The first one shows an unaltered bit, still fitted with its spring retainer.
As you can see, it has a dull tip that's entirely suitable for planing asphalt paving, but not very useful for marking survey points:
The next photo shows a bit with its retainer removed. This one has already been sharpened, though you can't really see the tip in the picture:
Although a silicon carbide (green) wheel is recommended for grinding tungsten carbide, I've never gotten around to buying one, so I used a regular aluminum oxide wheel. It's much slower, but for minor material removal it works okay. Here's a closer look at the sharpened tip:
The photos below show the result of using the punch on a regular 1"-long concrete nail, and an 8" spike.
I'll add a piece of red heat shrink tubing to the punch shank to make it easier to find in the weeds, but now I have a spare bit ready to be sharpened and put into service if needed. The cost, after tax and shipping, but just under $20 each.
> The photos below show the result of using the punch on a regular 1"-long concrete nail, and an 8" spike.
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I'll grant you that punching a hardened concrete nail is a pretty amazing feat. It would probably punch an axle, too. I'm less impressed by the punchmark on the 3/8" x 8" steel spike since a punch that cost about $3.00 will do that all day long and is so compact that it fits in one of the narrow front vest pockets.
I like about a 90-degree bevel on the tip of my $3.00 punch so that it makes a 1 to 1.5mm dia. mark that is also a bit deeper. The other thing that would concern me about the fat punch you've made is that it seems as if it would be harder to actually center the punch than would be true for an ordinary thin punch that doesn't hide as much of the piece being marked. Can't tell that from your photos, but it seems as if it would be true when things already in place are being punched.
Granted, an ordinary $3.00 punch is not at all up to punching hardened nails. I don't even try to do that (or even use hardened nails).
what is a source for these planing bits?
thanks for your help
which # 3.00 punch are you using?
thanks
I absolutely need this. Can you share the link of the source? 🙂
Thank you.
> which $3.00 punch are you using?
The last center punch I bought was either from Lowe's or Home Depot. It was a DASCO PRO 7/16 Center Punch 532 (with a 90-degree bevel on the tip, unlike the one illustrated at the link below)
You don't want a pin punch, which has a sharper bevel, and you do want a stouter punch like the 7/16.
> what is a source for these planing bits?
Your local Caterpillar dealer would be the first place to try. Mine is Holt of California, which happens to have an online parts facility. I had to set up an account -- no charge, and it took only a few minutes -- after which I was able to search for the desired part and place an order pretty much like any online store.
The Cat part number of the bits I bought is 351-2677. I believe it's called an asphalt cutter bit in the catalog.
> The other thing that would concern me about the fat punch you've made is that it seems as if it would be harder to actually center the punch than would be true for an ordinary thin punch that doesn't hide as much of the piece being marked.
It does, indeed, take a little more "peering over the top" than with a thinner punch to place the tip on target, but it's never been a problem. But the main advantage is its ability to punch hard metals without damage, and that's primarily what I use it for. Concrete nails, mostly, and the occasional manhole rim.
The one I recently lost was one of my favorite and most-used tools, so I'm glad that I now have a replacement.
For a thinner punch with a carbide tip, search for Rankin File's thread on automatic center punches, and you'll find my description and photo of the lathe dead center I bought. I've still got it in the truck and will play around with it, but I'm very glad to have a Fat Boy in the arsenal once again.
I haven't tried this but it looks interesting.
Jim. I don't know if it would work with a carbide tool, but wherever you lost your prior punch did you try to use a locator to find it? Just a thought.
By the way I like the new design. :good:
Scott
> Jim. I don't know if it would work with a carbide tool, but wherever you lost your prior punch did you try to use a locator to find it?
The problem is that I don't know where I lost it -- I can't even remember what job I last used it on. So I don't know where to start looking. 🙁
Found It!
While rooting around in a little-used corner of one of my truck's tool boxes yesterday, I came across the punch I thought I'd lost. It had jumped out of the tray it normally occupies and rolled into an obscure corner, which led me to conclude that I'd lost it. So now I have the original, a spare, and a spare for the spare.
Found It!
Thats just precious Jim 🙂 I bet you can get a pretty dollar for spare spares you have!
Found It!
The best part about finding the punch it is that I hate to lose tools I use regularly, particularly those I've had a long time, and more particularly those that are unique.
I still wince when I think about the pocket knife I lost somewhere near Lodi in the late 1980s. I had carried it for about 15 years, and I think it fell out of my pocket when I scaled a block wall to look for a monument. It was a Camillus SS 4-in-1 with the "US" stamp on the handle. I don't recall the year of manufacture, but I do recall that I got it at a garage sale for 25 cents, and considered it the best all-around knife I've every carried.
