Thread: Make a 5/8"tap

this looks interesting
Acme Screws & Thread Rods | Dependable Acme Threaded Products

This is the second tap in 5/8 - 8 LH

I could only take .003" cuts when thread cutting as the material tends to tear and leave scour marks on the thread flanks if deeper cuts are taken .

The neighbour has a oxy set for the hardening and tempering .

Mike

Hi Mike,
I have started making a 7/16" 10 tpi RH tap for the Rivett. I have had the same problems with the O-1, had to take small cuts. I roughed mine out first with a .030" wide tool, the surface on the bottom of the cut was appalling. With a tool ground to a a nose width of a bit less than .030" (the root width needed to be .03707") i cut the LH flank first, then went to size on the RH flank. I was only taking .01mm cuts at a time. The steel was cutting beautifully with these tiny cuts. I used flood coolant for the roughing and some tap magic for the final cuts.

Measuring to size was a pain though, the formula i attached earlier is all good and well, but with 10tpi i would have needed a .04872" dia wire.....not some thing i have! I calculated the measurement required over a .055" thread wire, it seems to have worked just fine. A pic of my workings is attached, i'll put the pics of the tap in the Rivett thread where they belong.

Cheers,
Ew

Originally Posted by Ueee

I calculated the measurement required over a .055" thread wire, it seems to have worked just fine. A pic of my workings is attached, i'll put the pics of the tap in the Rivett thread where they belong.

I confess to bypassing the calculations - I draw up what it should be in AutoCAD, including the wire sizes I have and then measure from the drawing the target dimension.

Michael

Originally Posted by Ueee

Hi Mike,
I have started making a 7/16" 10 tpi RH tap for the Rivett. I have had the same problems with the O-1, had to take small cuts. I roughed mine out first with a .030" wide tool, the surface on the bottom of the cut was appalling. With a tool ground to a a nose width of a bit less than .030" (the root width needed to be .03707") i cut the LH flank first, then went to size on the RH flank. I was only taking .01mm cuts at a time. The steel was cutting beautifully with these tiny cuts. I used flood coolant for the roughing and some tap magic for the final cuts.

Measuring to size was a pain though, the formula i attached earlier is all good and well, but with 10tpi i would have needed a .04872" dia wire.....not some thing i have! I calculated the measurement required over a .055" thread wire, it seems to have worked just fine. A pic of my workings is attached, i'll put the pics of the tap in the Rivett thread where they belong.

Cheers,
Ew

Ewan

That is good info from you

I used the 1942 Advanced Machine work book to work out the depth of thread etc .

BTW I was using neatsfoot oil but it didnt seem to be very effective.. I need some of that tap magic stuff !

Info I copied from a forum


With a tap, you want the cutting edges hard and sharp. You want the shank softer and tough.

You want it hard, but you don't want to burn the steel.

Take some iron wire, like the auto repair people use, and wrap the tap up in wire. NOT the zinc plated stuff! Now dip the tap in liquid hand soap. Neatness does not count, just cover it with plenty of wire and dip in soap.

The wire and soap will help exclude air from the tap and help keep it from oxidation during heating.

The other thing the wire does is give you something to hang onto while you do it!

Silver solder flux works here too, I am told, though I have'nt tried that.

Heat it up to "Cherry Red" and keep it there for a couple of minutes.

Quech in your "appropriate liquid" vertical while moving it around.

Remove the wire, and clean the tap.

Once you harden the tap, check it with a file. Should be harder than woodpecker lips!

Now clean and polish the cutting edges really well. MIRROR SMOOTH take your time, this part is important!

With the tap pointing up, and looking at the CUTTING EDGES with a magnifying glass, heat the SHANK at the bottom with the torch with a gentle flame....JUST THE VERY BOTTOM WHERE YOU TURN THE TAP WITH A WRENCH!

As the tap gets hotter, you will watch the color move up the tap toward the cutting edges.

When the CUTTING EDGES turn a pale straw yellow, quench immediately in you "appropriate liquid". This will stop the tempering process, leave the shank softer and tougher, and just temper the cutting edges.

The cutting edges at the front of the tap doe most of the work, and need to be hard, so don't over do it.

This is how the clockmakers make they're tools, and it works well for me....just go easy with the torch, it won't take much to do this

If you go too far, you have to go back to the beginnig and harden it again....and most steels don't like doing this too many times. practice on a piece of steel first, just to get the feel for it.

Practice,practice, practice.... The best way to learn is to do, get a piece of tool steel and harden it, you'll find out. THEN make your tap...

Originally Posted by morrisman

Info I copied from a forum


With a tap, you want the cutting edges hard and sharp. You want the shank softer and tough.

You want it hard, but you don't want to burn the steel.

Take some iron wire, like the auto repair people use, and wrap the tap up in wire. NOT the zinc plated stuff! Now dip the tap in liquid hand soap. Neatness does not count, just cover it with plenty of wire and dip in soap.

The wire and soap will help exclude air from the tap and help keep it from oxidation during heating.

The other thing the wire does is give you something to hang onto while you do it!

Silver solder flux works here too, I am told, though I have'nt tried that.

Heat it up to "Cherry Red" and keep it there for a couple of minutes.

Quech in your "appropriate liquid" vertical while moving it around.

Remove the wire, and clean the tap.

Once you harden the tap, check it with a file. Should be harder than woodpecker lips!

Now clean and polish the cutting edges really well. MIRROR SMOOTH take your time, this part is important!

With the tap pointing up, and looking at the CUTTING EDGES with a magnifying glass, heat the SHANK at the bottom with the torch with a gentle flame....JUST THE VERY BOTTOM WHERE YOU TURN THE TAP WITH A WRENCH!

As the tap gets hotter, you will watch the color move up the tap toward the cutting edges.

When the CUTTING EDGES turn a pale straw yellow, quench immediately in you "appropriate liquid". This will stop the tempering process, leave the shank softer and tougher, and just temper the cutting edges.

The cutting edges at the front of the tap doe most of the work, and need to be hard, so don't over do it.

This is how the clockmakers make they're tools, and it works well for me....just go easy with the torch, it won't take much to do this

If you go too far, you have to go back to the beginnig and harden it again....and most steels don't like doing this too many times. practice on a piece of steel first, just to get the feel for it.

Practice,practice, practice.... The best way to learn is to do, get a piece of tool steel and harden it, you'll find out. THEN make your tap...

Mike
Yep, have done this plenty of times & it works.
The tempering can be a bit tricky as its easy to overheat, I have found it best if you just take it slowly on the heating, of the shank, as you outlined, so that a straw to light brown is reached.up around the cutting edges. Sometimes it can be rushed & the tempering operation is ruined.
regards
Bruce
ps
I just did a test on the lathe parting off Silver Steel with varying lubricants
Tried Neatsfoot Oil, Tap Magic, Straight undiluted soluble Oil, & Soluble Oil.
The winner seemed to be the Soluble oil, in a flood.

Originally Posted by Abratool

Mike
Yep, have done this plenty of times & it works.
The tempering can be a bit tricky as its easy to overheat, I have found it best if you just take it slowly on the heating, of the shank, as you outlined, so that a straw to light brown is reached.up around the cutting edges. Sometimes it can be rushed & the tempering operation is ruined.
regards
Bruce
ps
I just did a test on the lathe parting off Silver Steel with varying lubricants
Tried Neatsfoot Oil, Tap Magic, Straight undiluted soluble Oil, & Soluble Oil.
The winner seemed to be the Soluble oil, in a flood.

Thanks Bruce

Have you ever made a morse taper tap ? I guess it is a similar thing to makinga threading tap , but without the thread.. mike

Mike
I think you may be referring to a roughing style, Morse Taper Reamer. Have not made one of these, although it would not be too difficult.
They are available at reasonably low prices, but I have not had the use for one.
regards
Bruce

Originally Posted by Abratool

Mike
I think you may be referring to a roughing style, Morse Taper Reamer. Have not made one of these, although it would not be too difficult.
They are available at reasonably low prices, but I have not had the use for one.
regards
Bruce

yes Bruce

I meant to write morse taper reamer , but I have taps on the brain right now

The taps are finished but it remains to be seen if they actually work

Originally Posted by morrisman

The taps are finished but it remains to be seen if they actually work

I had a visit with Mike (morrisman) today as I was in his neck of the woods, and witnessed these taps in the flesh.
I have no doubt that they will work, Mike has done exceptionally well and should be extremely proud of himself.
Now that I have said that, I will accept that Colchester as payment Mike..

Last week I got my 0.6X8tpi ACME tap made and tapped the nut... As explained earlier mine is made out of 4140 steel but left the steel as supplied, so it's hardness is only 30 or so on the Rockwell C scale..

3 flutes, and the cutting and back edge was ground on the TC grinder as the flute cutting left a very very jagged edge...

Cutting the thread int he nut was not easy, but it got done.... taper angle is 3 degrees included angle...