Author Topic: decent taps?  (Read 6119 times)

Offline stuart cee dub

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decent taps?
« on: May 05, 2014, 06:02:34 PM »
Good Morning All,
Last night I was drilling and tapping the barrel tang to trigger plate hole and one again was frustrated by the looseness of the name brand hardware taps I purchased some time ago .While still sharp ,they just seem to be oversize generally .

I use the drilled hole, bolt diameter down to the plate as a guide so I don't think it is technique .It is not wobbling . Sometimes I'll not run the tap all the way through just to keep it tighter .

Can someone recommend a source for an 8-32 and 10-32 tap ?
(Is this a Brownells thing?)
And is there a difference in taps?

Regards Stuart Cee Dub   

Roy

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Re: decent taps?
« Reply #1 on: May 05, 2014, 06:09:42 PM »
They might not be as sharp as you think they are or, it might be the bolts.. I use standard hardware taps all of the time btw.. Never really have a problem with them as far as what you are describing. I do know if the bolts or screws are turned a few thousandths smaller than what they are supposed to be you will get a loser fit..  Hope this helps.

Three balls

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Re: decent taps?
« Reply #2 on: May 05, 2014, 06:46:27 PM »
Stuart, there is most definitely a difference in taps, and I believe that standard hardware taps, tend to be on the loose side. Some aircraft taps, make very tight fitting threads.

Offline stuart cee dub

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Re: decent taps?
« Reply #3 on: May 05, 2014, 06:55:35 PM »
Hi Roy,
These are bolts that I got unplated from Track.
That may be a possibility of course.
Regards Stuart

Offline Jim Kibler

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Re: decent taps?
« Reply #4 on: May 05, 2014, 07:05:15 PM »
Two flute spiral point taps are great.  I order from MSC.

Offline okieboy

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Re: decent taps?
« Reply #5 on: May 05, 2014, 07:07:25 PM »
 Stuart, commercially produced threads are made in different fits, these are described as Class 1, 2, or 3. A Class 1 is a loose fit, like hardware store screws, bolts, and nuts. A Class 2 is tighter and is the most common fit used in most machining. A Class 3 is so tight that you may not be able to assemble threads with your fingers and have to use a tool (interference fit).
 In tapping you are adjusting your fit by choosing an "H" number. An H number represents how much bigger the tap cuts over a design starting point known as "basic". Both internal and external threads use basic as a starting point.
 When you look at your tap, it should show a designation on the side like "10-32 H3". The H means that the tap should cut basic plus 3 x .0005", or .0015" over basic. So, if you find H3 loose, the next choice to be tighter is H2. In 10-32 you should also be able to purchase an H1. An H0 would probably require having taps custom made.
 It is very unlikely that a hardware store is going to offer you a choice of H limits, so you will need to shop with industrial distributors. MSC would offer you extensive choices, but you would need to start an account; McMaster-Carr would probably have what you need, and you don't need an account and there is no minimum order.
 Hope this helps.    
Okieboy

mattdog

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Re: decent taps?
« Reply #6 on: May 05, 2014, 07:13:11 PM »
Taps are sold in three different precision sizes.  H1, H2, H3.  H3 is the loosest and is meant for day to day hardware store applications so that nearly any bolt/screw in that size will fit the threads.  H1 is the tightest and is meant for high precision fit of the bolt/screw to the threads.  When ordering from MSC and other industry cataloges they will be listed as such.  If you buy taps from Ace or other local hardware store it will likely be H3. 

Go to msc.com and take a look at their catalog.  Beware, they list over a million items.

Offline smylee grouch

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Re: decent taps?
« Reply #7 on: May 05, 2014, 07:35:07 PM »
Just wondering if drilling a hole a few thousands smaller would work. I have had like problems before and when I do a vent liner I always go small first.

Offline okieboy

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Re: decent taps?
« Reply #8 on: May 05, 2014, 07:52:50 PM »
 When you reduce the size of the tap drill, you reduce the "minor diameter" of a female thread, but has no effect on the "pitch diameter" which is basically the distance between the thread vees from one side to the other side, which is built into the tap. A lot of machine operators have trouble understanding this, that all it does is increase the thread percentage (the distance from the top of the thread to the bottom of the thread). Once a thread is at about 66% of its maximum height it is about as strong as it is going to get, but increasing the thread percentage will rapidly increase the torque required to turn the tap and thereby increase the chances of tap breakage.
 It suddenly occurs to me how much of my life has been devoted to taps, tap drills, thread mills and threading inserts.
Okieboy

Offline stuart cee dub

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Re: decent taps?
« Reply #9 on: May 05, 2014, 10:12:28 PM »
Thanks Okie and Mattdog ,
That was the kind of information I was looking for .
I have a brownells account so I'll phone it in and ask their expert .
If he knows about the H1 ,2 and 3 and has H2 ,I'll try that route.
If not, I now have alternatives.
 
Sadly the first taps I bought were marked made in the USA now all of off shore
origin.

On an earlier build ,once browned the fit did seem to improve.While I'm sure hardware taps are better than what was used back in the day ,loose fit bolts drive me nuts on any firearm.Must be a personal issue I guess .
Stuart Cee Dub 

Offline Acer Saccharum

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Re: decent taps?
« Reply #10 on: May 05, 2014, 10:20:35 PM »
High Speed Steel spiral POINT two flute Taps are what I use, ground threads, H3 limits. The spiral points shoot the chips forward, which is great for thru-the plate tapping. Blind tapped holes require that you stop, clean out the hole, and tap again to finish.

High Carbon taps tend to snap off in holes. I don't use them, unless it's all I have.

Tom
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coutios

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Re: decent taps?
« Reply #11 on: May 05, 2014, 11:02:25 PM »
  I agree with staying with High Speed Steel. A two flute gun tap,sprial point works well. Stay with a H-2 if you can get them. Most screws are on the sloppy side in my mind. Greenfield/Butterfield are good taps if you can find them.  I've not had to buy any in  a while ....

Regards
Dave

chubby

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Re: decent taps?
« Reply #12 on: May 06, 2014, 12:12:36 AM »
Staying with an h-1 or h-2 is better if your drill is cutting center, and when doing blind holes i always use a complete spiral tap, when tapping with these the chips will spiral up out of the hole no need to stop till at the bottom. these can be found in McMaster Carr or MSC there great to use!   Chubby

Offline Bob Roller

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Re: decent taps?
« Reply #13 on: May 06, 2014, 12:30:48 AM »
I have packed the flutes of a tap with grease to pick up shavings
and it helps a lot.

Bob Roller

mattdog

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Re: decent taps?
« Reply #14 on: May 06, 2014, 01:55:56 AM »
After reviewing these posts I seee that Oakieboy has it right and I had it backwards on the 1,2,3 tap fit.  Sorry for the confusion.

 :-[

billd

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Re: decent taps?
« Reply #15 on: May 06, 2014, 03:21:43 AM »
The difference in "H" limits is only .0005" per step.  It is unlikely you would notice a difference tapping by hand.  Buy good 2 flute H3 taps.   Stay away from China and Pakistan. 

Greenfield/Butterfield is owned by Kennametal as is Widia.  Their taps seem to come from all over the world.  Another good tap is OSG.  The last ones I bought came from Brazil, and they worked excellent.  Sandvik taps are mostly made in Sweden.  Excellent quality but very expensive.   Rieff and Nestor has a good reputation but I don't like them. 

A company I really like is North American Tool, http://www.natool.com   100% made in America.  However I don't think they will sell a single tap to an individual.  I order them from Jones Kinden Company,  http://www.joneskinden.com

I did get a bunch of 8-32 bolts recently that were oversize.  Your's may be undersize.   Try them in a nut and see if they are real loose.

Bill

Frenchy

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Re: decent taps?
« Reply #16 on: May 06, 2014, 08:35:12 AM »
I have found that the differences between H1, 2, and 3 DO make a difference in screw fit. That 3 & 4 flute taps are more stable than 2 flutes for hand tapping. I also use 'split' dies for making screws as I can vary the diameter a tad.
« Last Edit: May 06, 2014, 05:21:34 PM by Frenchy »