What's the Best Tap for my Application?

[usolutions]

I use anchor lube. What's your opinion on that brand?

I can not advise on lube brand, but I have good results with 220 weight machine way oil, I have a bottle like nail polish with bristle cap.

 

[hanermo]

Faster tapping will usually require less torque.
Yes, it´s also a very fast way to snap taps.

Deeper holes, at least 1 mm, may allow for more chip packing at the bottom.
8-32 is about 4.2 mm D, 3.6 mm PD.

As was suggested, cleaning and adjusting the clutch on the tapping head is probably a good idea.

Since Your use seems to be woodworking, I would try progressively larger drills, upto 0.1 mm oversize, at least.
Try the taps by hand, and You can feel how hard they are to turn.

Likewise, taps with extra relief might work.
Custom taps etc. may be as little as 200$.

Like always, machining is numbers.
How many are You doing ? per day, per hour, what ?
Is the loss a 10$ tap or a 1000$ piece of hardwood ?

How many holes do You successfully tap ? per week.

I would guesstimate that for woodworking apps in ridiculously long holes your customers probably have little/no idea or expectation of real hole D, PD, ultimate final strength of the fastener, or anything like that.

Simply using faster rpm, larger holes, and perhaps extra relief on the tap would perhaps work.
Good taps on good material should do 3000+ holes, with rare breakage.

For 4 mm deep 3/4 inch == 18 mm, perhaps 1000 holes per tap.
Mild steel is often gummy with surprise inclusions and hard spots.

4 mm / 18 mm deep is very very hard to do in MS.
It´s about 4-5x D or diameter of hole, classified as a Very Deep Hole, and MS makes the app harder.

These days there are speciality taps made to be driven by impact wrenches.
They are probably extremely strong - impact wrenches have ridiculous loads.
Call 2, ask for a sample.
Videos online.

 

[just Dave]

Hello all,

I am a blacksmith that makes cabinet hardware. I use a pneumatic tapping arm and tap blind holes 3/4" Deep with an 8-32 thread. Material is Mild Steel.
I currently use OSG, B2 H3, 3 spiral flute, bottoming, HSS or cobalt taps. I drill the hole on a drill press with a wire #26 bit prior to tapping. I use lots of quality cutting fluid, blow out the holes after drilling, and have a clutch drive on the tapping arm.

I have 2 main issues I run in to currently:

1. Screw does not want to go in all the way to bottom of hole. I often run in to this issue and am not sure why. Should I use a higher H factor? Would that mean
more room for the screw or less? I've read a lot on H values and pitch etc but I can't seem to wrap my head around whether or not a higher number means a tighter or looser fit. These are cabinet handles so I don't need a super tight fit, I'd rather have more room for error.

2. Taps break too often. Is HSS better for this than cobalt or another material? What do you sacfrifice with each option? What type of coating is best?

At the end of the day I'm looking for suggestions on the best type of tap for my application and why.

I respect you machinists greatly. What a science! I'm a humble blacksmith that prefers to bang on it till it fits lol.

Thanks in advance,

Nate

I would go with a spiral point gun tap. It will push the chips instead of pull them but I have a great trick to clean out. I would look for a Procunier tapping head. It will run well in a small drill press. Run 3-4 hundred rpm. This style tap is much more robust than a full spiral like you’re using. The best tapping fluid was outlawed years ago, for now I like Ridged pipe threading oil. Acid brush wipe on tap before each hole.A thin wire with a bent tip running in reverse 500 rpm or so ,will screw the chips right out of the deep holes. The Procunier is the key here. You can see them on YouTube. They have a cone clutch that is so smooth. I have tapped thousands of parts with one.

 

[just Dave]

By the way your spiral taps might work fine with a Procuneer.

 

[AARONT]

I use anchor lube. What's your opinion on that brand?

We use Anchorlube for anything difficult to tap. So far it's the best we've tried(never liked moly). I haven't tried the Mike-O-Cut though.