tap and die set

[srah1953]

Looking at the detail of a tap and die set, it shows contents of (say) 3 – 0.5mm and 3 – 0.6mm and so on for larger sizes. What do these numbers mean? Apologies if this is a dumb question.
Thanks

 

[Alpha22]

Is it that they refer to the three taps that make up the set for each size?
1- Taper tap
2- Intermediate or 2nd
3- Plug or bottom tap

 

[DinghyMan]

3 - 0.5 means 3mm with 0.5mm pitch, metric coarse
3 - 0.6 is odd, do you means 3.5 - 0.6mm as thats a standard size

 

[David2452]

If it had been say 1.0 & 1.5 I would have said thread pitch as you mention larger sizes, smaller sizes it still could be. Could be under size taps or oversize dies to allow first cut in hard material?

 

[srah1953]

The complete listing would read as follows-
METRIC sizes - 3-0.5mm, 3-0.6mm, 4-0.7mm, 4-0.75mm, 5-0.8mm, 5-0.9mm, 6-075mm, 6-1.0mm, 7-0.75mm, 7-1.0mm, 8-1.0mm, 8-1.25mm, 10-1.25mm, 10-1.5mm, 12-1.5mm, 12-1.75mm, 1/8 NPT-27

 

[DinghyMan]

The complete listing would read as follows-
METRIC sizes - 3-0.5mm, 3-0.6mm, 4-0.7mm, 4-0.75mm, 5-0.8mm, 5-0.9mm, 6-075mm, 6-1.0mm, 7-0.75mm, 7-1.0mm, 8-1.0mm, 8-1.25mm, 10-1.25mm, 10-1.5mm, 12-1.5mm, 12-1.75mm, 1/8 NPT-27

The 3-06mm is odd but the rest are all;

diameter - pitch

So its a set of most of the standard sizes with a decent range, last one is an imperial pipe thread

 

[srah1953]

OK. Thanks.
How would I know which pitch to use for misc screws into a mast?

I presume, answering my own question, is that you would use a screw pitch gauge?

 

[srah1953]

Sorry – a related question – once the hole is drilled and tapped, could I use a bolt (without nut) instead of a screw to hold an item on the mast? No sharp edge on the inside.

 

[nigelmercier]

How would I know which pitch to use for misc screws into a mast?
... could I use a bolt (without nut) instead of a screw to hold an item on the mast? ...

I'm no expert, but I think you need a fairly course thread for aluminum.

You ask "bolt ... instead of a screw...", it makes no difference as the threads are the same. I think what you really mean is if you need a backing nut. The answer depends on what you are fitting.

 

[VicS]

OK. Thanks.
How would I know which pitch to use for misc screws into a mast?

I presume, answering my own question, is that you would use a screw pitch gauge?

Sorry – a related question – once the hole is drilled and tapped, could I use a bolt (without nut) instead of a screw to hold an item on the mast? No sharp edge on the inside.

Just to add that the two pitch sizes for each diameter correspond to the ( normal) coarse metric threads and the fine metric threads.

If you have the bolt you can compare the thread with the tap if you do not have a thread gauge.



What alpha 22 says is also correct.
Taps all come in 3 forms. A tapered tap, an intermediate or second cut tap. which has only a slight taper and a plug tap which has no taper and would be used in a blind hole,
Your set proabably consists of only second cut taps. OK but need a little more care than when starting off with a tapered tap.


Bolts have hex heads and a plain unthreaded shank.
Set screws have hex heads but are fully threaded.
Machine screws have slotted pan heads or countersunk heads

Those are the common ones

Loadsa others of course.

 

[srah1953]

For this particular application I'm going to put a cam cleat on the mast to temporarily hold a halyard while I go back to the cockpit to tail it. But I'm also trying to understand the process for future use.
As it's into the mast I can't use a backing nut. [I can't use a river either because I can't find one that's long enough.] I'm not too pushed what type of head is on it as long as it holds.
I looked up the web for the difference between a nut and bolt and the answer below seemed the best. A screw normally screws into a surface whereas a bolt goes thru an opening, but once the hole is threaded, is there a difference in the strength provided by a screw over a bolt?

The simple answer is: The difference between bolts and screw are the applicable*standards*which define the requirements for the threads, and the applications they are used/intended for.
The official*definitions*are (Reference Machinery's):
"A bolt is a externally threaded fastener designed for insertion through holes in assembled parts, and is normally intended to be tightened or released by torquing a nut."
"A screw is an externally threaded fastener capable of being inserted into holes in assembled parts, of mating with a preformed internal thread or forming its own thread and of being tightened and released by torquing*the head."
There are*separate*standards*available for both bolts and threads, as well, as the grips, heads, etc..*

 

[nigelmercier]

...
I looked up the web for the difference between a nut and bolt and the answer below seemed the best...

This has been discussed here before. As Vic says, the main difference is that a bolt has a non-threaded section.

 

[DinghyMan]

These http://www.amazon.co.uk/exec/obidos/ASIN/B009SQACP0 are nice thread gauges or http://www.amazon.co.uk/gp/product/B005I51BX2/ref=wms_ohs_product for a decent set, easier to use than the standard one which is cheaper though http://www.amazon.co.uk/Faithfull-PITCHMA-Amer-nat-Metric-Screw/dp/B006TFI87W

 

[doug748]

By all means drill and tap your mast. I have seen it done, it works.

Masts are flimsy things though and you don't get many threads in the things.

I think I would use some of those rivinut efforts. From your comments above, you may have not got the full idea of how they work. Any road, check this out:

 

[nigelmercier]

These http://amzn.to/1CnjDW0 are nice thread gauges ...

I like the look of those, I often have trouble reading the legend on mine.

 

[David2452]

Sorry – a related question – once the hole is drilled and tapped, could I use a bolt (without nut) instead of a screw to hold an item on the mast? No sharp edge on the inside.

Personally I would use rivnuts on a mast as it is quite difficult to get a good thread tapped in the fairly thin ali, as for bolts, with pedant hat on I assume you mean a machine screw unless the item you are fixing is quite thick and does need a bolt with an unthreaded section (the difference between a bolt and a machine screw)

 

[DinghyMan]

I like the look of those, I often have trouble reading the legend on mine.

Only downside is that they have bloody sharp edges as they are stainless but do warn you on the cover

I like them as the pitch scales are not diameter dependent so you can check all the oddball thread sizes on switches and cable glands

 

[Topcat47]

I always use Monel fixings on masts and booms. This is both rivinuts and pop rivets They are expensive but will the rivinuts allow the use of SS bolts etc.... without bothering too much about dissimilar metals.

 

[srah1953]

Thanks for all the replies. Now that you remind me I have seen rivnuts mentioned here before. For the amount of work that I might do, I thought I was doing well equipping myself with a pop rivet gun and a tap and die set. Now it's suggested I use something else (imagine one of those non-smiley faces here).
I've edited my original draft because I didn't quite appreciate how rivnuts work.
Rivnuts seem harder to find (they don't come up on the Screwfix website). Where could I at a reasonable price equip myself with a rivnut installation tool and selection of rivnuts?

 

[surekandoo]

By all means drill and tap your mast. I have seen it done, it works.

Masts are flimsy things though and you don't get many threads in the things.

I think I would use some of those rivinut efforts. From your comments above, you may have not got the full idea of how they work. Any road, check this out:

+1 I've used riv nuts for mast fittings. I bought a simple setting tool based on two wedges. An Internet search will provide all the information.

I have been very satisfied with the result. Remember to use chromate paste if using s/s fixings in aluminium to prevent electrolytic corrosion.