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Why is this tap marked 5mm-.080?

rons

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
Didn't want to hijack this thread because of a similar issue.

https://www.practicalmachinist.com/vb/general/looking-4mm-075-fillister-head-screws-187417/

The tap is marked from shank to tip:
5mm-.080
MADE
IN USA
USE DRILL
11/64
LM
D5

I checked the pitch with a gauge and it is .80.
It's not a high quality tap but something like a Vermont American type from the hardware store. Purchased in my early days of home ownership. And that is
another issue. The cheapo taps that I grew up with are never used so I was thinking about getting rid of them and free up drawer space.

So why is the tap marked like this? A .080 pitch is 388 threads per inch.
 
Because someone at Vermont American screwed up where they placed the decimal point. Maybe he was coughing when he set the machine up, or he couldn't focus his vision...:D

Careful walking around out there. If things like this are keeping you up at night, some of the things that are everyday foolishness, are gonna leave ya with waking nightmares!
 
rons said:
I already have enough nightmare. I'm trying to remove this one from the bottom of the list.
Click to expand...

You could ADD one to heighten your sense of adventure? Or at least strive for a higher LEVEL of paranoia?

Lock this one into your wetware:

"six helicopters"

Don't even ASK what the question was. No one seems to know, nor ever did.

It was just the standard ANSWER one "helpful" Officer's School classmate would whisper into the ear of the guy next to him when an instructor had called-on him for dozing-off in class.

Anyone who FELL for it, leaped to attention and DELIVERED that answer with confidence?

Wasn't generally long for the program.

So it DID have "value"?

:)
 
I encourage you to give your consumer grade taps to your brother-in-law. Keep the quality taps for yourself. That's what I did.

I enjoy tapping much more now.

For the once every other year he taps something he's happy to have a selection.
 
I'll make a confession.

I have a suitcase tap and die kit FULL of cheap taps! Was $50 on sale at the local purveyor of cheap tools (Canadian Tire)

Without that kit, there is no way, I would be able to keep all those different sizes handy for when I want to clear mung out of one part or another, that comes across my bench.

May not be worth a pinch O' poo for MAKING a thread, but they work a treat for cleaning threadlocker and other filth out of one! Sometimes it's handy to have some tools around, that you don't feel too twitchy about having at with the grinder of torch.
 
Dumpster_diving said:
I encourage you to give your consumer grade taps to your brother-in-law. Keep the quality taps for yourself. That's what I did.

I enjoy tapping much more now.

For the once every other year he taps something he's happy to have a selection.
Click to expand...

Yeah, I will have to remember to use them for aluminium.
 
trevj said:
I'll make a confession.

I have a suitcase tap and die kit FULL of cheap taps! Was $50 on sale at the local purveyor of cheap tools (Canadian Tire)

Without that kit, there is no way, I would be able to keep all those different sizes handy for when I want to clear mung out of one part or another, that comes across my bench.

May not be worth a pinch O' poo for MAKING a thread, but they work a treat for cleaning threadlocker and other filth out of one! Sometimes it's handy to have some tools around, that you don't feel too twitchy about having at with the grinder of torch.
Click to expand...

I have a set too with dies. I have used some pieces in the set to clean out holes and reform threads.

I broke a cheap tap in my wood saw cast iron table while installing a Bieseymeyer fence. Stayed in there for years until I got a Dremel tool and ground it out and tapped the hole.
 
I have one of those old Vermont tap and die sets too.

The M5x0.8 is correctly marked. As I was looking, I found some other weird sizes.

There are M4's in both 0.7 and 0.75, and another M5 that is 0.9.
 
I recently needed a M7 x 1.0 tap. Even the local DXF supply house didn't have any...and they are a big operation that sells good stuff. McMaster had them but 2 days....

I went to AutoZone and they sold an entire China-crap tap/die kit ($25) which included the M7 tap. I decided to buy it. I took it back to the shop and couldn't help notice the tap was so dull it couldn't even drag on my thumb. It look terrible. I tried tapping a hole in 3/16" 6061 aluminum and it wouldn't even start. I rechecked the hole size...it was correct.

I took the kit back to the Zone and returned it....I made an attempt to tell the guy there why I was returning it and he looked at me like I was speaking Russian. Not only did he not understand what a tap was or why it needed a certain degree of sharpness, he also was wondering why I even felt the need to explain any return.

I still have no idea if anyone, ever, has actually gotten use out of their tap/die kit. I assume people must buy them and then decide to just buy a new car.
 
trevj said:
May not be worth a pinch O' poo for MAKING a thread, but they work a treat for cleaning threadlocker and other filth out of one! Sometimes it's handy to have some tools around, that you don't feel too twitchy about having at with the grinder of torch.
Click to expand...

Same thing, here, Japanese made in flat tin trays "back in the day" when Japan was still POOR, they are black-oxide HCS.

Why do it love that? IF/AS/WHEN I break one cleaning up FUBAR'ed threads?
It is waaay easier to get broken bits of HCS out than if they were the top-grade HSS I otherwise use.
 
They may exist, but I have never laid hands on a sold-as set of taps and dies that was good for anything but aggravation and curses. Buy your taps, tap wrenches, dies and die stocks separately, from good sources. Just do it...
 
sfriedberg said:
They may exist, but I have never laid hands on a sold-as set of taps and dies that was good for anything but aggravation and curses. Buy your taps, tap wrenches, dies and die stocks separately, from good sources. Just do it...
Click to expand...

The last shop I worked in had close to a dozen different boxed sets of taps and dies. All decent name brand stuff, lots of Butterfield. But we had a set of Metric, a set of Inch size normal stuff, another full of oddball inch size, that covered a lot of the Extra Fine Series taps, and a couple or three boxes of assorted British threads stuff for when we were working on Rolls Royce Jet Engines, BA, BSF, Whitworth, etc.

The replacement cost on a whole set like that is staggering, and certainly makes me deeply appreciate how available useable (if not always highest quality) tools are.

If everyone that needed a tap and die kit had to pay out those prices, I strongly suspect that there would be almost no folks involved in many of the hobbies we take for granted that many folks do.

If the only way to own a set of wrenches was to pay Snap-On prices, instead of Harbor Freight's, how many mechanics d'you think would be out there?

On the other hand, if you ARE making these holes for a living, and you don't have the appropriate go-no-go gages for the holes, how exactly, are you so sure that the threads meet spec? :)
 
So you checked the pitch and it is really 0.8mm. M5 - 0.8 is the standard, coarse thread for this diameter screw. It is only marked incorrectly. I see no reason to toss it except that it is a hardware store quality tap. I would say send it to me, but it is probably not worth the postage.

Just put it in a hole marked M5 and never read the shank again. Get a proper sized, 4.2mm metric drill bit: that 11/64 size is a bit large. So you don't need to read the shank for that either.



rons said:
Didn't want to hijack this thread because of a similar issue.

Looking for 4mm-.075 fillister head screws

The tap is marked from shank to tip:
5mm-.080
MADE
IN USA
USE DRILL
11/64
LM
D5

I checked the pitch with a gauge and it is .80.
It's not a high quality tap but something like a Vermont American type from the hardware store. Purchased in my early days of home ownership. And that is
another issue. The cheapo taps that I grew up with are never used so I was thinking about getting rid of them and free up drawer space.

So why is the tap marked like this? A .080 pitch is 388 threads per inch.
Click to expand...
 
thermite said:
Same thing, here, Japanese made in flat tin trays "back in the day" when Japan was still POOR, they are black-oxide HCS.

Why do it love that? IF/AS/WHEN I break one cleaning up FUBAR'ed threads?
It is waaay easier to get broken bits of HCS out than if they were the top-grade HSS I otherwise use.
Click to expand...

I had a wee reputation, as a bit of a miracle worker, at my old job, mostly based upon a willingness to think, and then patiently whittle away at small broken off screws and occasionally taps, stuck in very expensive, or completely unavailable parts of out aircraft.

Having made friends with the good folks over at the dentists office, I had a rather good supply of all the odd leftover dental burrs that they were never going to use, and they work very well for carving your way through little parts like that.

I long ago put aside my biases, and try to judge each tool on it's own relative merit vs. it's usefulness for it's intended purpose. I have bought far to many "Professional" grade tools that did not work or hold up to use, to believe that a higher price always gets you higher quality, and have had my fair share of bad experiences with cheap tool shaped objects.

For all that I have often seen the advice to have some HC Taps around, for the reason of easy removal, as well as that they apparently are sharper (while it lasts), I have never gone out of my way to buy any.
 
EPAIII said:
So you checked the pitch and it is really 0.8mm. M5 - 0.8 is the standard, coarse thread for this diameter screw. It is only marked incorrectly. I see no reason to toss it except that it is a hardware store quality tap. I would say send it to me, but it is probably not worth the postage.

Just put it in a hole marked M5 and never read the shank again. Get a proper sized, 4.2mm metric drill bit: that 11/64 size is a bit large. So you don't need to read the shank for that either.
Click to expand...

That is something to consider. If you can't trust one marking for the pitch why trust the second marking for the drill size.
Always refer to a safe chart instead.
 
35+ years ago I bought two new tap and die sets, one standard and the other metric. These probably came from the land of Corona virus. I had both sets for about 6 months before I needed to use a tap. I could not tap a hole or even thread a rod with the junk I bought. Tried to return it , no receipt , no return.
I did find a use for the dies, I use them for sinkers when I go fishing. Made a couple of punches from the taps. Threw the rest of the taps out.
 
rons said:
That is something to consider. If you can't trust one marking for the pitch why trust the second marking for the drill size.
Always refer to a safe chart instead.
Click to expand...

Chart? Nope. Math!

Diameter of the tap, subtract the pitch of the thread, equals drill diameter. 5mm - .8mm = 4.2mm drill.

Works for inch size taps too. Just need to convert the Threads Per inch into a pitch.

Nominal diameter, minus pitch, equals drill size!
 
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