Author Topic: Tapping help  (Read 8847 times)

Offline Robert Hornby

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Tapping help
« on: November 15, 2017, 12:43:50 AM »
Wherever possible I like to tap holes using the mill drill so that the tap is true with the drilled hole. On my smaller taps (8BA and similar) I made a special holder for the tap and it works well. However with taps in the order of 1/4" and upwards I use a standard tap wrench. The problem is that not enough (usually none) of the tap end protrudes through the holder to be able to support it from the drill chuck. I thought of grinding the square end down further to allow the wrench to go lower down. Any other suggestions out there?
Robert
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Offline Dave Otto

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Re: Tapping help
« Reply #1 on: November 15, 2017, 12:57:40 AM »
Hi Robert

For most of larger taps that have a center hole I use one of these spring loaded tap guides.
https://littlemachineshop.com/products/product_view.php?ProductID=1963&category=-561984047
It also has a small cup on the reversible center that can be used for the small taps that have the cone instead of the center.
A decent quality tee handle tap wrench will also have a center in the end that can be used with the spring loaded guide.

Dave
 

Offline Robert Hornby

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Re: Tapping help
« Reply #2 on: November 15, 2017, 01:13:19 AM »
Thanks Dave, but a lot of my larger taps don't have either a counter sink or are pointed at the end, ie they are just cut off square at the end.
Robert
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Offline AOG

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Re: Tapping help
« Reply #3 on: November 15, 2017, 02:04:16 AM »
I will second the recommendation to use a t style tap wrench and a spring guide.

https://goo.gl/images/tTK4bG

They work well for me.

Tony

Offline Jasonb

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Re: Tapping help
« Reply #4 on: November 15, 2017, 07:16:45 AM »
Make a female ctr for the ones without a hole or just hold loosly in the drill chuck to guide them.

I find tightening the tap wrench onto the plan shank gives enough grip to start the tap then if needed move it up to the square end and use without support

Offline Chipswitheverything

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Re: Tapping help
« Reply #5 on: November 15, 2017, 08:34:33 AM »
I tend to use Jason's method of just guiding by the drill chuck jaws.
Depending on the mill and the job, there may not be a lot of headroom to get a drill chuck, spring centre and the Tee wrench and tap length over the hole to be tapped.
 If, when clamping the tap by the shank, the tap wrench is held in the vice ( soft jaws !) and the wrench is done up with a well fitting tommy bar, it can be tightened pretty securely ( rather than holding the tap shank while tightening.) 
  If a more secure grip is wanted, you could use one of the smaller Myford type carriers on the tap shank, or make up an "old fashioned" type of wrench as in the photo, which can be tightened well if two socket screws are employed. 
Dave

Offline Jo

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Re: Tapping help
« Reply #6 on: November 15, 2017, 09:05:41 AM »
Hi Robert  :)

From your description you are interested in what we in model making would consider very large diameter tapping, i.e. 6mm + sizes. And you are right these big taps need a strong tap holder clamped around the square bit to be able to use enough force to cut the threads. The one at the top I needed to use recently on my No 5A for the little tap at the bottom but this was still difficult to square up and I had to start them by thread cutting on the lathe  ::)

Silly question: Are you starting with a taper tap? If you are then it should pull itself square very quickly from any slight misalignment you may cause. If you are threading short blind holes you might have to start with a second due to depth and that will not self alight so yes a bit of support wouldn't hurt  :thinking: If there isn't a centre already in the tap shank is it soft enough to add one?

The other option is to put a tool holding chuck like an ER32 in the drill quill and hold the shank of the tap with that. A standard drill chuck is unlikely to have sufficient clamping capability for the really big diameter threads.

Jo

P.S. Don't forget cutting lubricant  ;)
« Last Edit: November 15, 2017, 09:17:06 AM by Jo »
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Offline Ramon Wilson

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Re: Tapping help
« Reply #7 on: November 15, 2017, 12:01:32 PM »
Hello again Robert,

Were you to look in my motley collection of taps from smallest to fairly big (14-12 BA to 3/8-1/2 BSW) you'd find most of them have a flat ground (by hand) on one side just above the thread. This positions the tap holder and the portion of the shank above is held in the chuck, either very lightly closed jaws to guide the tap or in a brass sleeve held more tightly the bore of which is a nice slide fit on the tap.  This allows tapping with ease, in and out without any side pressures involved. I've been grinding these little flats on for years and though there's been the odd broken tap it's never ever been at the ground area so it does create a stress riser as such.

The flat just needs to be deep and wide enough for the wrench to bear against. I've found its much better to bear the flat against the fixed part of the wrench rather than use it as a flat for the moving part.

I've had a look through my pics but can't find any of this - I'm happy to take a couple should the above not be clear enough.

regards - Ramon
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Offline Ramon Wilson

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Re: Tapping help
« Reply #8 on: November 15, 2017, 12:13:05 PM »
Here you are Robert - this is from the Waller build, I think the tap is 12BA but the principle is the same on all taps.

The 'wrench' in this case is the knurled disc which gives much better control on tiny taps but once up to 8BA then normal flat tap wrenches take over



In use - the brass sleeve makes things much easier as the chuck jaws are tightened as opposed to being 'just tight'- 'just loose'.  The only problem with making a sleeve being is that there appears to be no standard on tap shank diameter sizes and some are very odd diameters indeed.


Hope that helps some  - Ramon
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Offline mklotz

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Re: Tapping help
« Reply #9 on: November 15, 2017, 03:32:22 PM »
I too use the mill drill as a tap guide when tapping.  After all, what could be better aligned with the hole you just drilled than the device with which the hole was drilled?

For larger taps (> 6-32) I made a low-profile, piloted tap holder that takes collets.  Each collet has a cut-away section that allows a setscrew to bear on the tap's flat section to keep it from rotating.  Only a few collets are required since many taps have the same diameter shaft.  The holder is shown on the far right in this photo of tap holders I've made...



The article about these holders is here...

http://www.homemadetools.net/forum/tap-holders-26298
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Offline fishy-steve

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Re: Tapping help
« Reply #10 on: November 15, 2017, 10:56:27 PM »

Offline mklotz

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Re: Tapping help
« Reply #11 on: November 15, 2017, 11:10:53 PM »
I use these.
http://www.warco.co.uk/tap-die/302931-spindle-tap-wrench.html
Steve.

I have several of those.  They're fine on the lathe but eat up too much z-axis room on the mill.
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Offline fishy-steve

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Re: Tapping help
« Reply #12 on: November 16, 2017, 11:44:23 AM »
Hi Marv,
I tend to use it straight into a mt2 collet untightened, which greatly decreases the head clearance required. I believe the shank is 1/4" diameter.
It does mean, however, that I have to drill the hole then remove the chuck and replace it with the collet  ;)
All the best.
Steve.

Offline Ramon Wilson

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Re: Tapping help
« Reply #13 on: November 16, 2017, 08:01:36 PM »
I don't know if you've looked back in to your question Robert but I was thinking about it today when tapping some holes as described.

So - for your edification I took these - hope they show just what a simple mod to a tap can bring without the need to make or purchase further kit (Not that there's anything wrong  with that Marv, Steve, but why spend time or money when it's not required  :) )

I really can't afford to break a tap in this casting




All successfully done - 5 BA by the way, 10mm deep



Hope that's of further use to you and others

Regards - Ramon
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Offline 10KPete

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Re: Tapping help
« Reply #14 on: November 16, 2017, 08:15:44 PM »
OK, gotta know...

Jo and Ramon: Tell me more about that little tap driver. The flat one with the dimple at each end and the little screw thingie to tighten the wrench on the tap...

Where are they purchased?????

Thanks,
Pete
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Offline Jo

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Re: Tapping help
« Reply #15 on: November 16, 2017, 08:18:44 PM »
I recognise that casting  :embarassed:

Sorry Pete, the Eclipse 244 tap wrench is not longer made  :disappointed: they turn up every now and then on Fleabay.

Jo
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Offline 10KPete

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Re: Tapping help
« Reply #16 on: November 16, 2017, 09:37:16 PM »
I recognise that casting  :embarassed:

Sorry Pete, the Eclipse 244 tap wrench is not longer made  :disappointed: they turn up every now and then on Fleabay.

Jo

Rats! It never fails... I'll be trolling eBay!

Thanks,
Pete
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Offline gerritv

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Re: Tapping help
« Reply #17 on: November 17, 2017, 03:04:06 AM »
Or make one? Looks worth while spending an afternoon on. Perhaps a separate thread where Jo and Ramon could post photos of a dismembered one with a scale (preferably metric) beside it. That should be enough to reverse engineer the thing.

I would be interested myself as working with small taps are in my near future!

Gerrit
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Offline 10KPete

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Re: Tapping help
« Reply #18 on: November 17, 2017, 03:36:19 AM »
Or make one? Looks worth while spending an afternoon on. Perhaps a separate thread where Jo and Ramon could post photos of a dismembered one with a scale (preferably metric) beside it. That should be enough to reverse engineer the thing.

I would be interested myself as working with small taps are in my near future!

Gerrit

I'm in Gerrit! If we can persuade Jo and/or Ramon to post some close up pics I think that would be enough. It looks pretty simple....

Jo?? Ramon???

Thanks,
Pete
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Offline Robert Hornby

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Re: Tapping help
« Reply #19 on: November 17, 2017, 04:42:53 AM »
Thank you gentlemen, and Jo for all the suggestions. I think Ramon's take on it will suit me best, so a little tool making time is needed between boat building.
Robert
Age and treachery will always overcome youth and skill

Offline Jasonb

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Re: Tapping help
« Reply #20 on: November 17, 2017, 07:26:09 AM »
And once you have made the 244 you will be wanting the 245 to go with it ;)

Offline engjas

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Re: Tapping help
« Reply #21 on: November 17, 2017, 07:27:05 AM »
Hello  Robert
Re the tap wrench have a look at patent GB670663A available on line I believe (Google patents or Espace)
Best wishes
John

Offline Ramon Wilson

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Re: Tapping help
« Reply #22 on: November 17, 2017, 07:42:19 AM »

Hi Guys -

I have to go out first thing but not for too long - once back I'll take some pics and dimensions for you. But at it's simplest form, a flat piece of 3-4 mm thick steel with a through hole and a 2.5mm grub screw in the side would easily handle up to say 4BA. That could be refined as far as you want to take it. You need a 'Trevor'  ;)

Back soon - Ramon
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Offline Jo

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Re: Tapping help
« Reply #23 on: November 17, 2017, 08:13:27 AM »
Re the tap wrench have a look at patent GB670663A available on line I believe (Google patents or Espace)
Best wishes
John

Yes that is the beastie  ;D

Jo
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Offline Ramon Wilson

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Re: Tapping help
« Reply #24 on: November 17, 2017, 01:18:57 PM »
Hi guys, further to Jo's info here's a bit more as promised



The wrench  measures 12.8 wide x 3.6 thick and is 95 .6 long OA. Dimple centres are apx 82.

The slot has a width of 5mm  opening to 6.9 mm wide where the knurled nut is.Knurl diameter is 6.3 and is 9.3 long.
From the point of the vee to the end of knurl is 32.8

The screw is L/H and looks 3/16 BSW but that's an estimate as there's not much to see. It has flats each side where it has been machined for the two guide plates

I do use the other two types in the same fashion but being thicker they need a longer flat ground on the shank - okay for the larger taps. I haven't found the CROZ one to be as good as it looked on the shelf! A nice looking piece of kit but not much use in this particular method of use!

Hope that helps - I'm in the throes of drilling and tapping an excessive amount of holes (200 plus) at the mo - 7 and 8 BA for the better part. Most will be done the way described above.

Hope that helps a little further

Regards - Ramon

Oh Yes - A 'Trevor'.

We had a rather recalcitrant member of the workshop who possessed few tools. Caught going through someones tool chest one morning and challenged he replied he was looking for a tap wrench. Told in no short order to buy his bloody own he disappeared to return with a length of 5/8 x 38 GFS in hand - a quick hole through and one through the side for a 6mm cap head and Trevor had his tap wrench. Used once it was thrown on the bench to remain there - left as a display by his colleagues as a reminder of his craftsmanship and belligerence. A tap wrench  (and a bodge ) was hence forth known as a 'Trevor'
« Last Edit: November 17, 2017, 01:27:20 PM by Ramon »
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Offline Ramon Wilson

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Re: Tapping help
« Reply #25 on: November 22, 2017, 08:49:57 PM »
Guys, Just a short addition to the previous posting.

Just finished off 224 7and 8BA holes in this fashion in two cylinder blocks.






The cylinder blocks are allowed to float but are prevented from rotation by the 'fixed stop' (angle plate left for previous op) and the magnet which helps do the same when backing the thread off.

This method does have something going for it - a small flat ground freehand on the tap is all that's required. The tap can be held by either gently closing the chuck to just support it or, as here, floating in a brass bush

As usual, hope that's of help and interest to someone.

Regards - Ramon
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Online sco

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Re: Tapping help
« Reply #26 on: November 23, 2017, 08:02:26 AM »
Ramon,

I really like the idea of this method - quick to move from hole to hole to start the next tapping operation and very economical on Z-height!  224 tapping operations though - do you use 2nd and then plug or straight to plug - that's a lot to do whichever!

Simon.
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Offline jadge

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Re: Tapping help
« Reply #27 on: November 23, 2017, 08:49:18 AM »
Ramon: I admire your patience. I'd have been idle and dug out my Tapmatic reversing tapping head. To partially answer Simon's question I often use spiral flute taps, even for hand tapping. You only need to buy, and use, one tap and they cut closer to the bottom of a blind hole than many bottoming taps.

Andrew

Offline Ramon Wilson

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Re: Tapping help
« Reply #28 on: November 23, 2017, 10:08:24 AM »
Hi Simon, Andrew,

I do have a Tapmatic under the bench Andrew but wanted to be absolutely in control of these small taps for as you can imagine I really did not want to break one in these two cylinders.

The taps I used were Blue Wizard HSS Spiral Point Taps. The immediate point of these were ground off and the holes drilled deep enough for the lead in taper not to have any effect on the stud thread. The points of these taps are very pointed and serve only for sharpening purposes. It can cause cracking/breakage of the tip if hitting the bottom of the hole too sudden, grinding the point back to a flat reduces this possibility immensely.
I have spiral flute taps too but I always feel they are are a much weaker tap due to the fluting so prefer to use SP when possible.

Had I had no choice but to use to use carbon taps I would have drilled the holes slightly larger diameter for less engagement, used the second tap as shown above, then, if necessary, gone back in with a plug tap using a chuck type wrench free hand.

As a matter of interest Simon this idea was borne of the need to overcome the lack of Z height on my old Linley machine  ;)

As you can see there's been a lot of holes to tap on these two parts and hope this will help those with limited kit overcome any doubt about taking on such a task.

Regards - Ramon
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Offline ShopShoe

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Re: Tapping help
« Reply #29 on: November 23, 2017, 01:35:37 PM »
Who among us has been using the Starrett tap handles? I keep wondering whether to add one to one of my orders when they turn up on sale. I have been considering making a copy of the older one as MrPete222 did. I have seen AvE compare the large one with a cheaper brand, but we use the smaller ones. I get by with the collection of cheap ones I have, but I also upgrade things as I go forward in this hobby.

I like a tight grip of the wrench to the tap so that the "feel" of the cut transfers to my fingers.

--ShopShoe

Offline steam guy willy

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Re: Tapping help
« Reply #30 on: November 23, 2017, 02:09:45 PM »
Hears my tuppence worth....I find that when tapping cast iron i do not need to use a taper or 2nd cut tap i just go in with a bottoming/plug tap ,also i use my old fashioned drill to tap holes by tightening in the chuck and turning the spindle from the top....photo to follow...Also using a magnet is a clever idea  As per Ramon !!
« Last Edit: November 23, 2017, 02:15:52 PM by steam guy willy »

Offline Stuart

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Re: Tapping help
« Reply #31 on: November 23, 2017, 02:19:35 PM »
Yes I like my Starrett tap handles and the Starrett chuck type I have a few a long reach one is useful

but I like my Elliot flat one ,its getting on in years now must be 30 to 40 years its a black one but its shiny at the end pity they don't make them any more

If I had to choose it would be a Starrett they feel so good in the hand   :Love:

Stuart
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Offline Jo

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Re: Tapping help
« Reply #32 on: November 23, 2017, 02:25:44 PM »
No one has mentioned the UPT   :Love: for tapping

Jo
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Offline jadge

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Re: Tapping help
« Reply #33 on: November 23, 2017, 02:55:58 PM »
I do have a Tapmatic under the bench Andrew but wanted to be absolutely in control of these small taps................

I should have known better. Note to self; keep mouth shut.  :-X

Andrew

Offline Jo

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Re: Tapping help
« Reply #34 on: November 23, 2017, 03:07:04 PM »
I do have a Tapmatic under the bench Andrew but wanted to be absolutely in control of these small taps................

I should have known better. Note to self; keep mouth shut.  :-X

Andrew

Hey Andrew never feel you need to do that. You mentioning it made me go and have a look to see how they worked: clever little gadget aren't they  :).

Jo
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Offline b.lindsey

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Re: Tapping help
« Reply #35 on: November 23, 2017, 03:16:50 PM »
They are Jo. I have one and used it a lot for secondary tapping operations mainly on plastics...a real time saver. Can't say I have ever tried it with smaller taps in metals, say 4-40 or smaller. They do have the benefit of an adjustable clutch though to minimize tap breakage, but even so, I can't see using on 0-80 or even 2-56 imperial sizes, more need there to feel the tap and how it is cutting.

Bill

Offline Ramon Wilson

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Re: Tapping help
« Reply #36 on: November 23, 2017, 03:46:04 PM »
Hi Willy- yes you can go straight in in cast iron but if it does grab it's a real bummer. I lost a 5BA in the base plate which fortunately I was able to drill out with a carbide drill and carry on but it was a real gut wrencher so early on in proceedings.

Andrew - that wasn't to be dismissive, merely that I do have one but decided in this instance to do it by hand for more control. The last time I used it was for 10BA taps in parts of the Bentley where it performed faultlessly but then it was in MS parts that could be remade.

One can have access to lots of good kit, but as said this was really to show the less fortunate that there are means and ways to get round problems with a lot less - just a little more patience required as you say.

I must admit though I'm glad this part of the build is behind me  :D

Ramon
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Offline Stuart

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Re: Tapping help
« Reply #37 on: November 23, 2017, 04:07:59 PM »
Jo if you want to live on the wild side just get out you battery drill sett the torque down low and use that to tap with ok down to 3mm  :lolb:


UPT I have a modded proxon drill that blew up so the table and column  have been repurposed to make a tapping stand

Each to their own method use what works for you , as a side note I only use HSS t and d all the metric taps are spiral flute but I have backup ones that are spiral point ( gun taps)

The difference for the readers is the first bring the swarf up out of the hole ( for blind holes ) the latter pushes the swarf out the bottom ( for thro holes)

Just my thoughts to muddy the waters  :stir:
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Offline Tonyr

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Re: Tapping help
« Reply #38 on: November 23, 2017, 06:12:34 PM »
Hello,

I realise this isn't really tapping info, but on small metric taps I have a few sets of series taps.
I don't think they are readily available in BA sizes etc but for metric taps they are available .
They really take the stress out of tapping small holes.

Tony

 

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