Broke a Tap

Your pictures show you maybe used the old 4 flute tap style? That style of tap does not do a very good job of dealing with the chips it makes. And so can bind up with chips very easily and break. The gun tap is my tap of choice. As it cuts the threads the chips are directed to the front of the tap. No real need to cut CW and then back off CCW like you would with the old style. You can just feed the tap in all the way with no fear of chip build up and use cutting fluid where applicable, Also, maybe the gun tap is a little stronger because of its two flute design…Good Luck
 
I don't do too much tapping... just every once in awhile. I have what I think is a good quality tap and die set (Hanson) that I bought back in the late 1970's. I was tapping a 3/8-16 through a 11/32" hole in mild steel, and it just wasn't working well. I had it nice and straight using a T handle with a live center in the tailstock, and used plenty of cutting oil. I even double checked the drill size to make sure I had drilled the right size hole. It was right at the point where I thought the tap was ready to break, so I backed it out of the unfinished hole, and went to the tool box to see if I had another tap. As luck would have it, I had recently acquired one in a tooling lot purchase. I didn't know it's history, but I mounted it up, and it cut just as smooth and nice as could be. I couldn't believe my original tap could have been that dull, but it obviously was. I chucked it into the scrap tooling bin (HSS that I save to cut new tools from), and bought a new one to replace it. Next time I won't fight it as long before trying a new tap.

GG
 
If you have never tried a high speed steel spiral point tap, you should. The difference between them and hardware store Hanson or Ace taps is nothing short of un-f-ing-believable.

After I made the "discovery" for myself, I literally gave away all my carbon steel taps, and have not looked back!
 
Everthing went good this morning,I had things lined up better.To start with I had the correct drill to use for the tap.So new drill bit /new tap and job went well.I go to put the screw in ans its to loose.Turns out there is a metric screw that fits closely to the thread gauge in the standard set.I had a metric screw the whole time.I went and got the correct screw and now all is good.Rookies , God help us.20141012_141126_zpsf539efb9.jpg

20141012_141126_zpsf539efb9.jpg
 
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I have yet to get the broke tap out of the other part.Dont think Im gonna mess with it,since I now have what I was going for.
 
Since I built my spark eroder I've used it 4 times. Very handy indeed particularly knowing I can make the repair there and then.
I will be playing with larger copper electrodes and square and triangular shaped ones for shaped holes.
Maybe hex to make my own socket screws who knows.
 
Now look what you've gone and made me put on my " To Do " list Savarin ........." Build a spark erosion machine , using my old stick welder " ( 90 volt open circuit )

It's ONLY number 57 on the list .:man:
 
savarin said:
Since I built my spark eroder I've used it 4 times. Very handy indeed particularly knowing I can make the repair there and then.
I will be playing with larger copper electrodes and square and triangular shaped ones for shaped holes.
Maybe hex to make my own socket screws who knows.
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I like the idea of putting in square holes , especially on round bars turned up out of square bar that fits the tool post , either in the end square on or ...at an angle as a small single leg fly cutter or on the side for that could make a fantastic boring bar tip holder .

Do you use a single set shaped electrode/tip or is it a series of small electrodes strategically placed in a round hole to get the square one ?

Do you have any idea of the smallest square hole we can expect to obtain using the spark erosion technique?

Another thing about it is that I may be able use spark erosion techniques to make some small steel moulds to free or centrifugally cast some aluminium or wax parts as I don't have a mill ( Yet ! )
........ Do I " Darling ", :whistle:says Dave to his wife < who has just popped int othe room and peeked at what he's typing . ) :happyhappy:
 
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george wilson said:
As I have mentioned before,I have a few sets of Chinese made carbide end mills,from about 1/32" to about 1/8" in assorted steps. They are probably metric. I have used them several times to mill out broken HSS taps when I was the toolmaker in Williamsburg museum. Others would bring their broken taps in gun springs(or other stuff they SHOULD have tapped before hardening!!) I ran the Bridgeport as fast as it would go. With the assorted carbide milling cutters,I could find a size that would mill out the tap,leaving the threads perfectly intact.

I used to buy these sets at a gun show from a guy who sold import tools. They were $10.00 for a box of 10 small carbide end mills. They are great little taps. I wish I could find more of these sets. They are well coated with TIN.
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Do you have a photo of the packaging, bits, or remember the name of the manufacturer or tool dealer. Even if the dealer died, his unused website can stay up for years.(if he had one)

I will try to hunt these down.

Thanks,

Chris
 
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