Creating bottom taps

[Kludge]

Somewhere in my checkered past, I remember someone telling me that if I had an extra tapered tap and wanted a bottoming tap that's not available or handy to run the tap carefully into a matching die, snap off the end of the tap and dress the remaining part, then back it out of the die to finish cleaning up the threads.

Of course, that could also be med-induced delerium, too.

Any thoughts?

Best regards,

Kludge

 

[Stan]

I seem to have no shortage of bottom taps created accidentally from taper or plug taps.

 

[joeby]

Kludge,
Maybe you were thinking of cutting a bolt that way, and backing it out to clean off the burrs. I would just use a nut for that though.
Running a tap through a die I would consider to be a bad idea. It would most likely ruin the cutting edge. I just grind them flat on the end and chamfer the first couple threads. Be careful when hitting the bottom of your tapped hole though, the flutes of the tap can wedge themselves fairly tightly into the corner where the drill diameter meets the tip angle, most times resulting in a shorter bottoming tap!

Kevin

 

[Maryak]

Somewhere in my checkered past, I remember someone telling me that if I had an extra tapered tap and wanted a bottoming tap that's not available or handy to run the tap carefully into a matching die, snap off the end of the tap and dress the remaining part, then back it out of the die to finish cleaning up the threads.

Of course, that could also be med-induced delerium, too.

Any thoughts?

Best regards,

Kludge

Just cut the tapered part off with an angle grinder and dress the bottom on a bench grinder.

Best Regards
bob

 

[Kludge]

Maybe you were thinking of cutting a bolt that way, and backing it out to clean off the burrs. I would just use a nut for that though.

I probably was. That's why I asked. My meds and the reasons for them tend to make things a bit fuzzy now and then so I'd rather ask and look a fool then not ask and be one.

Be careful when hitting the bottom of your tapped hole though, the flutes of the tap can wedge themselves fairly tightly into the corner where the drill diameter meets the tip angle, most times resulting in a shorter bottoming tap!

And a shorter hole which kind of defeats the process.

I like itty bitty sizes that often mean watchmaker's tools like dies (actually die plates) & taps. The problem is the taps are all taper taps and sometimes I'd really rather not drill a through hole. I figured that buying a spare set and converting them would be a good move but that's where my memory clouded up.

Thanks!

BEst regards,

Kludge

 

[Kludge]

Just cut the tapered part off with an angle grinder and dress the bottom on a bench grinder.

Lemme think. Angle grinder. That would be one of the grinding wheels on the Taig. Bench grinder. That would be the grinding wheel (wet) on the 8mm watchmaker's lathe. ;D

I keep having to translate all the big boy toys to what fits my shop but I got the idea. I think it may even be doable. The taps I have in mind run from .6 to 2mm in .1mm steps and the ones from India (Anchor brand) aren't all that bad. (Side note: The ones from China are getting better but aren't quite ready for prime time.) The more common sizes 00-90 and up I can generally find but the really small ones are ... well, they don't exist.

Thanks!

Best regards,

Kludge

 

[Kludge]

I seem to have no shortage of bottom taps created accidentally from taper or plug taps.

Hmmm ... anything from 8-32 (or 8-40 or something of similar diameter) on down ... if you find you have excess ... ;D

BEst regards,

Kludge

 

[joeby]

I probably was. That's why I asked. My meds and the reasons for them tend to make things a bit fuzzy now and then so I'd rather ask and look a fool then not ask and be one.

No appearances of being a fool from where I stand!

I keep forgetting to scale down my thinking here anyway. I'm more accustomed to taps and dies from 1" on down to probably 4-40 being the smallest I normally work with.
I have taps down to 0-80; but just started filling in the die collection below 4-40 a short time ago. I have built several engines, and have numerous engines in various stages of completion; but I haven't gotten down to the small scales you seem to like working in. You will need to remind me of that from time to time, as I forget that the things I "know" will not necessarily apply to these small scales.

As I go along in this model engine building business though, I might ask for your mailing address as a method of disposing of my excess home-made bottoming taps in the smaller sizes!

Kevin

 

[speakerme]

I have had no problems taking the tap to the grinder and flattening the bottom to where it just begins to cut threads, it is neater and cleaner than buying a new tap for a job that you are trying to complete.

Best Wishes

Chuck M

 

[Kludge]

I have had no problems taking the tap to the grinder and flattening the bottom to where it just begins to cut threads, it is neater and cleaner than buying a new tap for a job that you are trying to complete.

But then don't you wind up with having to buy replacement taper taps later anyway? Granted this is how I'll have to make all my itty bitty bottom taps but that will be done using a duplicate set so I have both taper & bottom. (I guess I don't really need plug taps if the phase of the moon is right.)

Just sayin', y'know?

BEst regards,

Kludge

 

[Tin Falcon]

There are lots of tap styles out there. I tend to buy assorted styles of taps. I have the spiral flute,spiral points, forming taps etc.
Spiral flute taps are best For blind hole when power tapping but can be used by hand. The chip is pushed up and out chip breaking not needed.
.
Spiral point taps are best for through holes as the chip is pushed through the hole. again no chip breaking.
Thread former taps create no chip so can be used blind or though but requires larger pilot hole are limited to malleable material work best fast power tapping and give a stronger thread.
Hand taps IMHO have limited used are best for one or two holes or thread chasing. They break easily and can not be used under power because of required chip breaking.
One shop I worked in the guy that bought tooling only knew of and purchased one kind of tap 4 flute plug hand taps. so if we needed a bottoming tap we ground the tip off.
Tin

 

[Kludge]

There are lots of tap styles out there. I tend to buy assorted styles of taps. I have the spiral flute,spiral points, forming taps etc.

Cool information, Tin. Thanks! Even this old dog can learn. Might not remember but I can learn.

In the watchmaker's sizes I know all I'll find are straight flute taper hand taps but I'll keep your advice in mind for where I can find a choice. Since I can't see going over a #8 (or 1/8") screw for much of anything other than pipe taps, this may limit my choices but I'm always open to laying in different types of taps. At the same time, I can't think of anywhere I would be using power tapping either ... well, not in this venue. (I have a few antenna projects in mind, on the other hand. )

I have a hand tapping tool that will keep the forces in line to reduce the chances of breakage (One of Northwest Shortline's tools for model railroading.) which is amazingly useful for hand drilling as well. One of its shortcomings is the lack of any real way to hold a workpiece in place but I have a few thoughts on how to resolve that issue without the use of high explosives.

Again, many thanks for the information. Consider it swiped to my "Cool stuff to know" file.

BEst regards,

Kludge

 

[scoop]

Not strictly to do with bottom taps but could be a useful tip.We used to machine quite deep threads in a very nasty sort of cast aluminium and the threads had to go to within about 0.015" of the hole bottom,I seem to remember that they were in a rolls royce industrial gas turbine compressor casing,anyhow the metal was horrible and taps would just clog up and tear the threads out of the last 0.250" or so of the holes no matter what type of taps we used.Spiral flute taps gave the best result but a combination of the material and coarse thread and the fact that they had to be machine tapped meant that any thread could tear without any warning.We then tried some things called "tapsticks" don't know if this was a trade name or just a general name but all they are is a fairly hard tallow rod,a bit softer than a candle and no wick obviously.Using a size approx .020" smaller in diameter than the drilled hole,a piece about 2/3rds of the depth of the hole was broken off and dropped in.when tapping started a quick squirt of tapping fluid for each hole was put in and as the tap wound its way into the hole the tallow compressed into the bottom of the hole and then forced its way up the flutes of the tap carrying all the swarf from the tap with it.When it reached the bottom of the hole there were 3 neat extruded strips of tallow (one in each flute)impregnated with ali swarf poking out of the holes.As the tap retracted all the tallow was came out with the tap and was just brushed off before going to the next position.Never failed to produce a clean hole and all done on a cnc machining centre at production speed.Obviously we probably will not need to tap this fast at home but if you ever need to tap a fair few holes it can save you from having to keep on winding the tap out of holes to clear it.I dont know if these sticks are still available or if anybody out there still remembers them as this was back in the early eighties.
I don't know if this information is of any use to anybody but at least it is another ramble down memory lane for me though if nothing else.I think I still had hair then.

best regards Steve C.

 

[Tin Falcon]

for your casual bedtime reading you can download a Greenfiel tap and die catalog here more than you probably wanted to know about taps.
Tin

 

[shred]

For 90% of my tapping, which is almost all done by hand, I like the spiral point "gun" taps that push the chips ahead. Those are great on through-holes and even not-deeply-tapped blind holes.

I do always wonder why 2-56 taps are almost 2x the price of 4-40's or anything larger in the Enco & MSC catalog. ???

 

[Kludge]

Scoop: That is utterly cool. I love it and have saved it to my cool things to know file. Thank you!

Tin: Grabbed and saved. Of course, "bed time" tends to be catch as catch can for mer but it still is some cool reading. Many thanks!

Shred: I think everything in general below a 4-40 goes up in price since they're the ones more commonly broken (personal opinion - no facts to back it.) and the makers know it so charge a lot for replacements because they can.

I need to check what sizes I can get the various types of taps in to make life more comfortable. I don't mind spending a little extra (well, I do because of my pension) to get taps that work as they should. Some will be in odd sizes (#x-40 up to 8-40 & 1/8"-40, for example) because I think they will look better by being uniform where the threads actually do show.

It's like the head sizes - 1/8", 3/16" & 1/4" round, hex or square dependent on availability and independent of the screw sizes when I'm not using pre-made watch screws. (Actually, this is out of pure laziness on my part.) Smaller heads will be used for the sub-metric ones but I'm not sure how much smaller.

Anyway, thanks for the advice. I do appreciate it.

Best regards,

Kludge