poor man's square broach

[frugalolegeezer]

Gee, that takes a load off of my shoulders after reading some of the posts on here, I thought sure I was a hoarder, " wow" I had an inkling I was not one of those people that cannot throw anything away until it rots or molds. I will have to convince my wife to read this and quit pointing her finger at me and raising her eyebrows. Thanks folks, you just saved my marriage.

[Frank S]

My grand father had a saying you keep something for 7 years if you have't used it by then you need to dig it out take another look at it then build a storage place for it label that space and keep it another 7 years. You will probably have used it or traded it by then for something else to keep for 7 years.
When he died at the tender young age of 97 there was this one storage space that had several dozen feet of hand made decorative molding that hadn't been produced in over 70 years. On of my uncles decided that since there was so much stuff some of it might have a little value to someone so they had an estate auction I wasn't at the auction but I heard that the hand made molding which was left over from a house my grand father had remolded was bought by the folks who owned the house for a 4 figure price how much of a 4 figure price I don't think I ever heard but I doubt if it was on the smaller side.
Hoarding? I don't see it that way as long as you eventually get around to using it or are willing to part with it at some time.

[Murph1090]

I've done a similar trick by pressing a spiral reamer through a length of seamless tubing to cut rifling into it for air guns (or regular guns, for that matter!)

Works much better than one might think.

[garage nut]

Great idea. Need one some 6 x 6mm HSS insert.
Small problem....need a 8.5mm Tap. Is there an imperial size close to 8.5mm Diameter.

[Frank S]

The closest thing would be a 5/16" but at /312 that is only be 7.9mm the next size being 3/8" .375 would be 9.5 which would probably be the best size to grind square if using a corse thread tap there should still be enough of the threads left to do the cutting.

[garage nut]

Going to try it with a M8 tap. Can not take too long to file out 0.25mm per side with a needle file.
Still fantastic idea.
Will this handle changing a 6mm Dia hole in a 12 x 12mm bar I want to use as a boring bar. Bright MS as it is only to open up a brass bush.

[Paul Alciatore]

That's a great idea. I will have to try it.

As an added thought, I have found that pawn shops in my area often have used taps available for 10% or 15% of their new price. Sometimes even less. I have purchased bunches of them and tumbled them in walnut shell media to clean them up. I have even gotten complete sets this way: taper, plug, and bottom taps; all the same brand and tolerance so they were probably purchased as a set originally.

Most clean up to a usable state, but those that don't could easily become square broaches. Heck, event the good ones could easily become broaches and at a low cost.

I wonder if the three flute ones could become triangular or hex broaches. The hex may require two passes.

How about a "D" shaped hole? Or one with a key? This has my imagination going.

[Frank S]

Paul A, if you were to calculate the depth of cut required for a key-way grind 1 flute flat then grind the remaining 3 to the diameter it is feasible to make a key way broach the problem stems from the body of most taps having deep reliefs cut between the flutes. However since all of the threads would be ground off on the 3 flutes at best the bore would not be effected, at worst it might be scored but should otherwise remain un damaged You would want to use long taper taps for key way broaches.Non fluted machine taps might be best for this as well.

[Captainleeward]

Way to go Frank....:O)

[garage nut]

Don't try it on a piece of 22mm dia solid MS.



Fortunately I felt my little 5 ton manual press was struggling, so covered it with lots of rags and an old jacket so when it let go it was not too dramatic.

Ended up just filing it to square. Gave me a good start at least.

For thinner stuff I am sure it will work