How do you make a Hardy hole

[Steve McCarthy]

I have a broken fork from a large froklift that I plan to use as an anvil. It's 50 in. long 8 in. wide and 6 in. thick. Anybody have suggestions on how to make a square hole?

[Doug C]

here is a prior thread on the topic.

[Donnie]

You could weld a piece of heavy walled square tubing to it for a quick fix.

[Sam Salvati]

Got any of that forklift tine extra?

[SGropp]

An accurate square hole through a 6'' thick piece of what is likely some really tough steel? Try taking it to some place that does waterjet cutting, although it might cost you a bunch for just one hole.
Personally, I'd just skip it and put the hardy either directly in the vise or in a socket made from square tube or welded angle iron.
I very seldom use a hardy at all , preferring to cut hot work with a hack or v cutter under the power hammer or with a handled hot chisel under the treadle hammer. I usually put a piece of scrap aluminum or soft steel under the work to protect the bottom die.
I have had good luck making hot cut tools out of pieces of octagonal crow bar stock.
I forge to shape at bright orange, anneal in vermiculite, grind and polish to sharpen and use as is ,cool regularly with water in use. Keep the tool short if it is for use under a power or treadle hammer.

[Steve McCarthy]

Thanks for the ideas. For now I think using a vise is my best option.

[DC712001]

Have you considered a "Square Hole Drill Bit?"

Drilling Square Holes
by Scott Smith

A bit that drills square holes ... it defies common sense. How can a revolving edge cut anything but a circular hole? Not only do such bits exist (as well as bits for pentagonal, hexagonal and octagonal holes), but they derive their shape from a simple geometric construction known as a Reuleaux triangle (after Franz Reuleaux, 1829-1905).

Here are links:

http://upper.us.edu/faculty/smith/reuleaux.htm

Reuleaux triangle - Wikipedia, the free encyclopedia

Reuleaux Triangle -- from Wolfram MathWorld

Problem: So far, I haven't been able to find a supplier that sells these drill bits (unless you can make your own?)

[NeatGuy]

square hole drills were invented and sold by "Watts Brothers Tool Works" of Wilmerding, Pennsylvania. USPTO link for those who are interested Publication Images They are still in business and still make drills that can drill polygon holes. Here is a scanned catalouge http://metalworking.com/dropbox/Watts_Bros_manual.pdf Contact information is included in the catalouge.

brad

[Woody]

take a 3/4 inch drive socket drill a hole just big enough for it to fit very tightly then drive the socket into the hole. Tack weld in place

[DC712001]

Thanks for the links Neatguy. Good to know there is a source for Square-Hole Drill Bits.

Wondering...are they prohibitively expensive (ballpark prices?) I understand you also need the "special" chuck to allow the drill-bit to work.

[matt87]

Weygers' The Complete Modern Blacksmith details a few different ways of drilling square holes, including making the bits. It's a great book, though IMO he places too much emphasis on grinding rather than forging. (Some of his practices with grinding wheels would make most people run in fear of their bodily appendiges though...)

[Black Maple Forge]

I made a hardy hole on my anvil by drilling a round hole, then chiseling() it out to a square. It took a LOT of time, but works:rolleyes:...

[bruce wilcock]

wrap your apron around your neck, and poke the gas cutter in from the bottom side till you prick it through then square it up from the top side ,then drive a taper drift in with a 56 lb sledge whilst there is a bit of heat in it ,no one can se the hole when the tools are in it , you can borrow our heavy sledge .

[ThomasPowers]

A few quick musings:
the hardy hole is used for a lot more than just cutting with a hardy

6" is a deep hole, deeper than hardy hole in my 400# traditionally made anvil.

I would probably torch out a slot on the end of the piece and weld in a piece of heavy wall square tubing---but not a full 6" long piece as you want to be able to pop a hardy tool out if it becomes stuck---when making hardy tooling the shaft should extend out from under the hardy hole and be tapered so it doesn't rivet itself in place if you have stuck it very well indeed.

The press fit of a large drive socket is an interesting method as the tine should be drillable with industrial quality drill and bits.

Drilling a sq hole that deep would probably not be a possibility in this material.

[Hillbillysmith]

I was surprised to see that I am not the only one who has ever heard of the Reuleaux Triangle! It is surely a fascinating tool. I don't know if this link was already put up but this Reuleaux Triangle link has pretty neat visuals on it. Click on some of the blue pictures and the files at the bottom and play with the angles.

-Hillbilly

[Steve McCarthy]

WOW. I am really supprised at the amount of discussion generated by the question of a first time user. I REALLY appreciate all of the suggestions. I think the idea from Thomas will prove to be the simplest answer. Thanks again for everyones input.

[NateDJ]

I finally decided to drill a hole in mine and insert a square tube and weld it up. seems to work so far. I would suggest a larger than a 1/2" square however ...

[patrick]

The fabricated hardy hole option has been mentioned, but I thought I'd point out a neat variation on this. An engineer here in WI fab up his anvil froma large block, say 8x8x24. He welded a hardy hole on one side, but designed it so that there is a cam lock lever coming out of one side. This allows him to tightly lock in hardys which don't other wise fit tightly, without jamming them in and getting them permanently stuck in the hole. It was a very well thought out and executed design.

Patrick

[Finnr]

The Idea ROCKS Patrick. I may just have to play with that!
Finnr

[rthibeau]

Woody's socket welded in strikes me as the finest kind of idea to keep things simple.........if you can drill through the thing. I bent a fork lift tine to make an anvil stand and know it ain't gonna be easy!

[Frosty]

In my opinion welding in an impact socket is THE way to retrofit an anvil with a hardy hole.

The camlock is an intriguing idea as well. Hmmmmm.

Frosty

[ChrisB]

Get the impact socket. Take it and the fork to a machine shop and ask them to cut a hole at your desired spot that is undersize for the socket yet correct when the fork is heated with a torch. Once home freeze the socket and heat the fork. Once together weld from the underside.

[KYBOY]

I bought this ol' homemade RR track anvil at a yard sale for $10..To have a beater,etc..I knocked a hole in it with a torch for a pritchel hole and then welded 5/8" square stock to form a hardy hole in the back...The few hardys I use in it are made with shanks from MC railroad spikes which are 5/8". Works out perfect..

[philip in china]

How much space do you have? If you have enough why not get an ASO with a hardy hole init and just use that as a hardy holder? It is all they are fit for.

[Warren Nakkela]

Most larger metal fab shops now have flame cutting machines. Six inches are quit a lot to pierce, but it can be done. It will need a lot less preheat if you drill a starting hole. You may need a carbide drill. Good luck.
Warren
Don't fall in love with your first idea.