2-56 tap – can only buy one

This topic has 14 replies, 8 voices, and was last updated 16 May 2018 at 22:19 by Nimble.

Viewing 15 posts - 1 through 15 (of 15 total)

Author

Posts
15 May 2018 at 06:25 #354064
Thaddeus Swarfburn III
Participant
@thaddeusswarfburniii
I need to cut 2-56 threads in phosphor bronze for my Rudy Kouhoupt mill engine. Years ago I bought a Woodlands Scenic Hob-bits tap from the hobby store where I worked. Looking at it does not instil confidence that it will cut clean threads or not snap in the job.

If I purchase only one decent tap for this job, what style should it be? I expect I'll use a drill press to guide the tap while I cut by hand. Most of the tapped holes in this job will be blind, so I'm assuming I'll need to use a bottoming tap. Am I pushing my luck starting threads this size with a bottoming tap?

Any recommendations for brands available on Amazon would be a plus as I will be in the States for a couple of weeks soon.
Advert

15 May 2018 at 06:25 #18927
Thaddeus Swarfburn III
Participant
@thaddeusswarfburniii
Plug or bottoming?
15 May 2018 at 06:52 #354067
David George 1
Participant
@davidgeorge1
Hi I would recommend Tracy Tools as they deliver very quickly and have never had a bad purchase. I also think it is false economy to try and use one tap and risk having to remove a broken tap especially small taps.

David
15 May 2018 at 07:02 #354069
JasonB
Moderator
@jasonb
Why not get a tap you are more likely to use in future and also be able to get fixings more easily. M2 would be a very close substitute.

A spiral flute tap would do the blind holes but would need carful guiding if doing by hand so I would tend to suggest picking up a set of 3 taps though a lot will depend on how deep you can drill the blond holes, if say 5x dia then you can just use a taper tap which would gibe at least 2D engagement before it hits the bottom but will require the swarf clearing out a couple of times on the way in.
15 May 2018 at 09:15 #354081
Trevor Crossman 1
Participant
@trevorcrossman1
Having just tapped nearly 200 small holes in a crankcase and luckily without any breakage, I would suggest that you buy the highest quality set of taper,2nd and plug HSS taps that you can find regardless of cost. I have another 36 holes to thread 2-56 and again will use a new high quality set. Why risk scrapping an item that is an investment of several hours careful work for a broken tap. Trevor.
15 May 2018 at 11:59 #354096
Anonymous
I'd use a spiral flute tap. Only one tap needed and it should get you within a couple of pitches of the bottom of the hole. It's easy enough to use them by hand, even though they're usually thought of as machine taps. The "official" metric equivalent is M2.2, but a more practical (very close) substitute is 8BA.

I wouldn't even dream of buying a tap on Amazon. Buy a quality brand from a commercial tool stockist.

Andrew
15 May 2018 at 15:57 #354111
Thaddeus Swarfburn III
Participant
@thaddeusswarfburniii
Posted by JasonB on 15/05/2018 07:02:34:

Why not get a tap you are more likely to use in future and also be able to get fixings more easily. M2 would be a very close substitute.

A spiral flute tap would do the blind holes but would need carful guiding if doing by hand so I would tend to suggest picking up a set of 3 taps though a lot will depend on how deep you can drill the blond holes, if say 5x dia then you can just use a taper tap which would gibe at least 2D engagement before it hits the bottom but will require the swarf clearing out a couple of times on the way in.

Spiral flute is a good idea but that's gotta be really fragile at these sizes. I don't know as I'm any more likely to use M2 than 2-56. Seems like most of the steam engine plans I see are imperial anyway. Also, I've already purchased the hardware in 2-56!
15 May 2018 at 16:03 #354112
Thaddeus Swarfburn III
Participant
@thaddeusswarfburniii
Posted by Andrew Johnston on 15/05/2018 11:59:37:

I wouldn't even dream of buying a tap on Amazon. Buy a quality brand from a commercial tool stockist.

I was looking at brands like Guhring, Redline, or Tool America. Looked at Tracy Tools UK; I'll have to email about spiral flute availability as they don't list it as stock. And they ask £10 for shipping to NZ.
15 May 2018 at 16:22 #354113
Anonymous
Guhring would be on my list of suitable suppliers; I have no knowledge of Redline or Tool America.

Andrew
15 May 2018 at 16:43 #354116
John Reese
Participant
@johnreese12848
Posted by Andrew Johnston on 15/05/2018 11:59:37:

I'd use a spiral flute tap. Only one tap needed and it should get you within a couple of pitches of the bottom of the hole. It's easy enough to use them by hand, even though they're usually thought of as machine taps. The "official" metric equivalent is M2.2, but a more practical (very close) substitute is 8BA.

I wouldn't even dream of buying a tap on Amazon. Buy a quality brand from a commercial tool stockist.

Andrew

Andrew,

Many top quality taps are available on Amazon: Dormer, Guhring, YG1, Widia, Union Butterfield, Sandvik, OSG, Titan, Kodiak, Morse, and more. You just have to be particular about which brand to purchase.
16 May 2018 at 17:21 #354226
Thaddeus Swarfburn III
Participant
@thaddeusswarfburniii
So has anyone successfully used a spiral flute two in 2-56 size? I've found a couple of quality ones but am hesitant to drop half a day's pay on a tool that may not be suitable.
16 May 2018 at 18:36 #354233
Anonymous
Not 2-56 but I've tapped about 800 8BA holes, blind and thru, in brass under power; at 800rpm if I recall correctly. The tap was spiral flute, by Dormer.

Andrew
16 May 2018 at 19:18 #354238
Neil Wyatt
Moderator
@neilwyatt
Why can you only buy one?

Tracy Tools do carbon steel for £9 a set of three or HSS for £27.

My experience with PB is you will probably be OK with carbon steel if you keep it down to 60% thread engagement.

Neil
16 May 2018 at 19:34 #354241
Anonymous
Posted by Neil Wyatt on 16/05/2018 19:18:53:

Why can you only buy one?

Because if it's spiral flute you only need one tap per thread size.

Personally I've had bad experiences with taps from TT, so don't use them any more.

Andrew
16 May 2018 at 22:19 #354262
Nimble
Participant
@nimble
How about tapping all your holes with the taper tap, and when finished grind off excess length to reduce tap to a bottoming form. If in future you need to tap more holes you could then justify the purchase a new taper tap. Alternatively you could also counter bore the hole slightly to allow a bottoming tap to be aligned.How much thread engagement do you need? If you have plenty of depth you could use shorter screws or shorten your screws as per an earlier thread on screw shortening screws

Neil

Edited By Nimble on 16/05/2018 22:31:50
Author

Posts