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Chris165
10-17-2012, 11:02 PM
My lathe does not have threading right now and I need to make some parts. A while ago a friend had mentioned that he had some taps that were a set of three in which the amount of material removed progressed until the final thread dimension was reached. Kind of like a roughing, intermediate and finish tap. I'm looking to tap some holes by hand in 1x8 and 1-1/4x8 bottoming type is preferred. I have the regular taps but it is a pain to go full depth in one pass by hand. If anyone knows if this type of taps are still made or where to get them in the U.S. please let me know.

Juergenwt
10-18-2012, 12:02 AM
That used to be the way to tap. In European small shops it is still used. Forget about it and buy standard machine taps HSS, spiral point.

rustamd
10-18-2012, 12:05 AM
My lathe does not have threading right now and I need to make some parts. A while ago a friend had mentioned that he had some taps that were a set of three in which the amount of material removed progressed until the final thread dimension was reached. Kind of like a roughing, intermediate and finish tap. I'm looking to tap some holes by hand in 1x8 and 1-1/4x8 bottoming type is preferred. I have the regular taps but it is a pain to go full depth in one pass by hand. If anyone knows if this type of taps are still made or where to get them in the U.S. please let me know.

They are still available, look for taper, plug and bottoming tap set.

Fasttrack
10-18-2012, 12:29 AM
They are still available, look for taper, plug and bottoming tap set.

Don't think that's quite the same thing. The taper/plug/bottoming refers to how the tap terminates. It's good practice to start with a taper tap and then finish the hole with a bottoming tap if it's blind. Otherwise run the taper tap all the way through. There is no need to do any more after the taper tap, as long as you've run it all the way through or as long as you don't care about the last several threads.

What Chris165 is talking about would require all three to be used to achieve the full thread. I know this is common on square threads like Acme, but I don't think I've seen them for normal 60* machine threads.

My vote is to get yourself a high quality HSS tap and do it in one go. Get a big enough tap wrench that it doesn't take a lot of grunting or do it in your lathe under power. That's what I would do.


By the way, for through holes, spiral point taps are great. They push the chips ahead of them and makes tapping much easier. If you get a good one, they should have a 60* divot in the end which makes it super easier to power tap in your lathe. Just support the a@@ end with a dead center in the tailstock and rest the tap wrench handle on the carriage. Start the lathe and follow the tap with the tailstock, applying gentle pressure.

becksmachine
10-18-2012, 01:43 AM
By the way, for through holes, spiral point taps are great. They push the chips ahead of them and makes tapping much easier. .

Somebody correct me if I am wrong, but I have never seen spiral point taps larger than 3/4"?

The OP is looking for 1" and 1-1/4"

Never mind, MSC has them up to 1-1/2" if you know how to use their search function, which I obviously don't. :o
Dave

John Stevenson
10-18-2012, 03:42 AM
Chris is looking to tap 1.25" x 8 tpi which even using a taper tap will take some muscles and a fair sized tap wrench.
The progressive taps are also called serial taps.

I have a set in standard metric, very good for tapping things like stainless and titanium that can work harded in a heartbeat if you are not careful. Also very good in Aluminium bronze

http://www.stevenson-engineers.co.uk/files/serialtaps.jpg

As well as having the shorter tapers as you move from taper to second to plug the OD also progress's until the last tap is full size.

Can't offer any advise through over where to get some taps in the size Chris wants though, sorry.

small.planes
10-18-2012, 03:55 AM
Cant really add much to what JS said, Ive got the same type, also in metric upto M12.
I have however used just 1 and 2 when I needed a 'self locking' thread, which can be handy on occasion.

Dave

EVguru
10-18-2012, 04:25 AM
Arc Eurotrade sell 'serial' taps, but only up to M12 or 1/2"

http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Taps/Serial-Taps---Metric-BSW-BSF

Both major and minor diameter are reduced for the first stages, but how about grinding down the OD on a tap ans a first pass?

johnnyd
10-18-2012, 05:48 AM
http://www.e-taps.com/

This is where I got mine.
They only stock metric sets, but he can have a set made for whatever size & threadform you want.

philbur
10-18-2012, 08:18 AM
I believe you can get up to 8 taps in a single set, not just the commonly used taper, second and plug.

Phil:)

Fasttrack
10-18-2012, 08:28 AM
I believe you can get up to 8 taps in a single set, not just the commonly used taper, second and plug.

Phil:)

Aside from the "serial" (thanks, John!) and taper/plug/bottoming styles, you can also get different thread clearances. And then there are different coatings, spiral flute, spiral point, etc, etc

Lots of variety! :)


Enco carries spiral point taps in 1-8, by the way. A little cheaper than buying direct from MSC.

Black Forest
10-18-2012, 12:17 PM
If you look at the picture John posted you will see on two of the taps there is a ring or grove around the shank. One will have one grove and one will have two groves and one will have no grove. The one will no grove is the last tap to be used. I have a whole set of this type of taps up to 12mm. I didn't know that I was to use the three taps to make one threaded hole. I just thought they gave me three of each size. I broke some of the finish taps when I tried to make the thread in one go. Also when I used the first tap in the series and then tried to screw in a bolt and it didn't work I thought my expensive German made taps must have come from China. Then I learned on here about the series hand taps!!!! I don't use them at all. I just bought Walter taps and was amazed at how easy it was to tap with these great quality taps. I routinely tap 20mm by hand with no problems.

Mcgyver
10-18-2012, 01:59 PM
Somebody correct me if I am wrong, but I have never seen spiral point taps larger than 3/4"?

The OP is looking for 1" and 1-1/4"

I think serial taps in the large sizes make a lot of sense....or even some of the awkward small ones like 10/24. I almost never break a tap (now i've done it) but you have hold hold the tongue just so to avoid breaking 10/24's in tough material.

Fasttrack
10-18-2012, 02:16 PM
I think serial taps in the large sizes make a lot of sense....or even some of the awkward small ones like 10/24. I almost never break a tap (now i've done it) but you have hold hold the tongue just so to avoid breaking 10/24's in tough material.

I've got some 1-56 taps I need to try out sometime ... I've done 2-56 in 1/4" 316 SS. I had to hold my tongue, clinch my butt, and twirl around three times naked under the moon before attempting. No tap breakage to report. I recommend this procedure to anyone attempting a difficult tapping job.

Paul Alciatore
10-18-2012, 03:39 PM
I have a set of metric taps in this style. I got them from Grizzly several years ago and they were not clearly marked or advertised as to the style so it was a surprise when they arrived. The first tap only cuts about 50% of the thread depth, even if you go all the way to the end of the threads on it. The tops of the threads have been ground off. The second tap increases this to 70%, but a screw still will not fit the hole. You must use the third, 100% tap to get the full thread.

As others have said, it is a great way to prevent tap breakage as each tap only has to cut part of the thread.

The down side is you MUST use all three of them in the proper sequence. So, it takes at least three times as long to tap a hole.

I sometimes use them in my battery powered drill with a clutch setting that is less than the max to allow slippage if it jams. I would recommend a clutch setting as low as possible while still driving the tap. This will speed things up, especially if you are tapping multiple holes. Dip tap in cutting fluid, tap hole, reverse drill, repeat for next hole. Repeat for second and for third tap in series. Poor man's tapping head. But it works great.

I would not deliberately choose this style of tap as my primary ones. A spiral point tap is probably best for that. And yes, you can take a standard set of taper, plug, and bottoming taps and grind them to 50% and 70% threads to make your own set. For the tooling purists, you do not need clearance on the OD of a tap because it does not cut sideways. So just grinding them to a new diameter is just fine. I would recommend using a fine wheel and cutting fluid to keep the finish on the OD as nice as possible. This will keep friction down while tapping which will also help prevent tap breakage.

Chris165
10-18-2012, 07:40 PM
I sent an e-mail to e-taps today for quote on the listed taps and they would have to be made due to the size. Unfortunately the cost of the taps prohibit their use because I only need them for two parts.

small.planes
10-19-2012, 05:11 AM
For small taps I use the most rigid tapping stand I own:

http://i306.photobucket.com/albums/nn274/small_planes/SSC_4621.jpg

http://i306.photobucket.com/albums/nn274/small_planes/SSC_4623.jpg

This is tapping M1.4 (~1.4mm dia). I made hundreds of these:

http://i306.photobucket.com/albums/nn274/small_planes/DSC_4641.jpg

and didnt snap a single tap :) Which was handy as I only bought 1...

Dave