I am making forming taps for 3/4 and 1" Three and four feet long. I am
drilling and taping into lead 13 inches deep. Then I screw althread
stock into the taped hole and then set in epoxy. My question is what
type of steel shank extentions should I use.
The next question is how do I connect to the shank end of the tap.
This is what I have been doing so far and every thing has worked ok so
far but I might be just lucky.
I take for lets say a 3/4 10 forming tap, a 5/8 drill rod and bore one
end to .400 about 1.250 long. The other end of the drill rod I make
the same as the end of the standard tap. I then grind down tap shank
to .4006. I then heat up the drill rod to dull red and drive the tap
in. I cool the drill rod with a rag soaked in water. I next have
champhered drill rod tig welded up for a little extra force. Grind
flush the weld and use it.
Question #1 what should I do to the drill rod to make it stronger.
#2 does the heating of the end of the drill rod make it weaker?
#3 should I use drill rod or somthing like m2 tool steel. or 4130
post an answer or email me at

In article , Don Huseman says...

... I next have
champhered drill rod tig welded up for a little extra force. Grind
flush the weld and use it.

Be careful as some of the materials used to make
taps will become brittle if tig welded, I've seen
them snap near the weld if done that way.

As mentioned, silver soldering is a better approach.

Jim

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JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
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jim rozen wrote:

In article , Don Huseman says...

... I next have
champhered drill rod tig welded up for a little extra force. Grind
flush the weld and use it.

Be careful as some of the materials used to make
taps will become brittle if tig welded, I've seen
them snap near the weld if done that way.

As mentioned, silver soldering is a better approach.

Jim



Couldn't agree more. Silver solder is a wonderful thing.

michael

What kind of silver solder? How much silver should general purpose have in
it?

--
RellikJM
RellikJM AT Yahoo DOT Com
Don't forget about my "FREE" EPROM programming !
Advice is only worth what you paid for it!

"michael" wrote in message
...
jim rozen wrote:

In article , Don Huseman
says...

... I next have
champhered drill rod tig welded up for a little extra force. Grind
flush the weld and use it.

Be careful as some of the materials used to make
taps will become brittle if tig welded, I've seen
them snap near the weld if done that way.

As mentioned, silver soldering is a better approach.

Jim



Couldn't agree more. Silver solder is a wonderful thing.

michael

In article y7HZa.119481$YN5.84974@sccrnsc01, RellikJM says...

What kind of silver solder? How much silver should general purpose have in
it?

Not silver bearing soft solder, which is used with an iron and
has a ~700F melting point. You need a silver braze or silver
solder that is used with an O/A torch, something like handy
and harmon's ez-flow.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

ff wrote in message ...
Don Huseman wrote:

I am making forming taps for 3/4 and 1" Three and four feet long. I am
drilling and taping into lead 13 inches deep. Then I screw althread
stock into the taped hole and then set in epoxy. My question is what
type of steel shank extentions should I use.
The next question is how do I connect to the shank end of the tap.
This is what I have been doing so far and every thing has worked ok so
far but I might be just lucky.
I take for lets say a 3/4 10 forming tap, a 5/8 drill rod and bore one
end to .400 about 1.250 long. The other end of the drill rod I make
the same as the end of the standard tap. I then grind down tap shank
to .4006. I then heat up the drill rod to dull red and drive the tap
in. I cool the drill rod with a rag soaked in water. I next have
champhered drill rod tig welded up for a little extra force. Grind
flush the weld and use it.
Question #1 what should I do to the drill rod to make it stronger.
#2 does the heating of the end of the drill rod make it weaker?
#3 should I use drill rod or somthing like m2 tool steel. or 4130
post an answer or email me at



What about 4130 tubing, 5/8 od with about 1/8 wall and silver braze your
tap in the end. This is for a sailboat keel, right?

Fred

I can't afford to break a tap off. I am using what I think is the
strongest
way I know. I also have to have the end of the tap fit in a tap collet
on my procunier tap machine. I am driving the tap with at least 1 hp
of my 2 hp mag drill motor. But good idea mybe using 4130 heavy walled
tubing would be better but the cost is about $50 to 100 verses 6 for
drill rod

In article , Don Huseman
says...

Heat shinking is very strong and I know that a lot of parts including
rail road wheels are attached to the shafts that way. I have never
seen a comparison of silver soldering to heat shrinking, If any body
has seen the comparison I would like to know.

Yes it is very strong. It will be weaker if shrunk in place
*and* tig welded. The welding can ebrittle the tap under
certain circumstances and if not annealed the tool steel
can break ajacent to the weld.

Siver solder like that typically has about 20 to 30 ksi tensile
depending on how the joint is made up - a proper joint will be
as strong as the steel it is connecting.

Shink fits like that are tough to quantify because the
surface finishes can vary greatly and change the amount of
interference that is supposed to exist.

I would think a shink fit combined with the method of drilling
a cross hole in a reduced diameter at the bottom of the hole
in the extension would work well. This produces what amounts
to a square sided hole which will drive the tap nicely.

This is how procunier fabricates their tap collets.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Don Huseman wrote:

jim rozen wrote in message ...
In article , Don Huseman says...

... I next have
champhered drill rod tig welded up for a little extra force. Grind
flush the weld and use it.

Be careful as some of the materials used to make
taps will become brittle if tig welded, I've seen
them snap near the weld if done that way.

As mentioned, silver soldering is a better approach.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================
Heat shinking is very strong and I know that a lot of parts including
rail road wheels are attached to the shafts that way. I have never
seen a comparison of silver soldering to heat shrinking, If any body
has seen the comparison I would like to know.
Don

There are shrink-to-fit systems available for tooling used in machining centers. My knowledge
of them is mostly limited to the fact that I can't afford one. They reportedly work quite
well, so I've heard.

michael