tap and die set

I want to make a screw thread inside a tube (the internal diameter of the tube is 1.55mm) then make a screw from wire to screw into the tube.
I bought a small tap and die set but maybe its not the best and I managed to break one of the taps already and still not managed what I want. It was a set 07-20 and I was told they were millimeters which made me think I'd have no problem but they just dont match up
Can anyone tell me now to calculate what I need or better still what tap and die to buy that will do what I want? I dont want to spend a fortune either as its just an idea that may not work at the moment.
Thanks
Helen

Helen, My first question is do you have a vernier gauge or micrometer in your tool set? because when using small taps and dies you will need to measure holes and wires accurately, or you will keep breaking taps. For small diameter metric threads I use Bergeon taps and dies, they are sold as watchmaker's tools. I will try to explain how to find the correct size tap, if you are sure that the internal diameter of your tube is 1.5mm. then that should be the size of the bare section of the point of the tap, just before the thread starts on the tap. Make sure you always use a lubricant when cutting threads. The correct size wire diameter should be the exact or slightly smaller width of the widest diameter cutting section of the tap you used to thread the tube.
Most good tool suppliers sell bergeon taps and dies, buy a die holder and a pair of pin tongs and then only buy the sizes of tap and die you will be using, buying a complete set is usually not needed, I try to use mostly the same size threads on most jobs.
I make all of my own nuts from tube and sheet and also thread wires to make screws and such like, check out my album.
James (Goldsmith)

One used to have a laminated booklet called the Zeus Table in the workshop with the clearance and cutting sizes listed, fortunately the internet has everything now: table.

I see that 1.55 is a bit inconvenient, but it should take an M1.8 thread.

Tap (Thread) Size Drill Size(mm)
M1 x 0.25 0.75
M1.1 x 0.25 0.85
M1.2 x 0.25 0.95
M1.4 x 0.3 1.10
M1.6 x 0.35 1.25
M1.8 x 0.35 1.45
M2 x 0.4 1.60
M2.2 x 0.45 1.75

The "x 0.35" means that the distance between the threads is 0.35mm. You need to make sure that your tap and die (for the screw) have the same pitch - not hard for this one as I think there's only one standard coarse pitch at this size.

As James says, buying just what you need is best, especially as small taps and dies are very expensive. A cheapo set from Machine Mart (040219154) will set you back £38 - this does have an M1.8 as it happens.

Now the really difficult thing is using them!

Taps come in pairs and you should use the pointier one first.

As James says, they need lubricating. I find oil best as waxes tend to glue the swarf into the threads. Rotate the tap or die slowly up to a quarter turn then rotate it back that same distance. This cuts the swarf into the grooves and helps spread the lubricant onto the next piece. Make up the quarter turn you lost and progress a further quarter turn before backing it off... and so on. This is slow and tedious but always works.

Sometimes, with the right clearances and lubricant you can skip all the reverses... but then one day the tap breaks off and you glumly promise yourself you won't do that again as you try to get the broken bits out...

After using the pointy one, remove it and run the less pointy one through - you won't need to do the backing off this time with such small sizes. This sets the size correctly where the pointy one is sized for making the first cut.

Threading the screw piece is basically just the same. You don't often get adjustable dies at this size so that's less to worry about. If you have two dies supplied as a pair, use the one with the bigger hole or indentation first... but I think it's pretty unusual to make pairs at this size. Again progress slowly and reverse at least 1/4 every turn.

Dear Helen,
Adding to what James and Joe have said, a big problem when cutting threads is to avoid wobble which makes for a loose fit. So I clamp the tube horizontally in a grooved vice to avoid distorting it and hold the tap in a pin vice, so that I can turn it with a supported hand. For the screw, I clamp the die and introduce the wire with a pin vice held horizontally as before.
kind regards, Dennis.

As a postscript, silver screws are ok as a permanent cold connection, particularly with a little adhesive added, but quickly become slack when undone a few times. D.

I can't find it now,but there are some online video from MIT of basic engineering workshop practice.It has a section on using taps and dies. They will help anyone who is starting to make jewellery in a few areas,of understanding drilling,and if you have a lathe or drill press.

I never really measure anything,just find the one that fits. Remember to turn the tap back every few turns to break the swarf off now and again,that's what causes them to break.

Quote:

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Originally Posted by Goldsmith

Helen, My first question is do you have a vernier gauge or micrometer in your tool set? because when using small taps and dies you will need to measure holes and wires accurately, or you will keep breaking taps. For small diameter metric threads I use Bergeon taps and dies, they are sold as watchmaker's tools. I will try to explain how to find the correct size tap, if you are sure that the internal diameter of your tube is 1.5mm. then that should be the size of the bare section of the point of the tap, just before the thread starts on the tap. Make sure you always use a lubricant when cutting threads. The correct size wire diameter should be the exact or slightly smaller width of the widest diameter cutting section of the tap you used to thread the tube.
Most good tool suppliers sell bergeon taps and dies, buy a die holder and a pair of pin tongs and then only buy the sizes of tap and die you will be using, buying a complete set is usually not needed, I try to use mostly the same size threads on most jobs.
I make all of my own nuts from tube and sheet and also thread wires to make screws and such like, check out my album.
James (Goldsmith)

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Thank you James, I looked at your album and WOW - absolutely amazing!
I think the tap and die is is more complicated than I first imagined as I was just trying the taps in the tube to see if they fit. The only measuring device I have is a digital caliper and the internal diameter of the tube I take from what Cooksons tell me it is but maybe thats not precise enough. I will stick at it though, I'm completely self taught so even many basic items are a mystery to me. I really very much appreciate you taking time to explain. Many thanks

Quote:

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Originally Posted by Joe

One used to have a laminated booklet called the Zeus Table in the workshop with the clearance and cutting sizes listed, fortunately the internet has everything now: table.

I see that 1.55 is a bit inconvenient, but it should take an M1.8 thread.

Tap (Thread) Size Drill Size(mm)
M1 x 0.25 0.75
M1.1 x 0.25 0.85
M1.2 x 0.25 0.95
M1.4 x 0.3 1.10
M1.6 x 0.35 1.25
M1.8 x 0.35 1.45
M2 x 0.4 1.60
M2.2 x 0.45 1.75

The "x 0.35" means that the distance between the threads is 0.35mm. You need to make sure that your tap and die (for the screw) have the same pitch - not hard for this one as I think there's only one standard coarse pitch at this size.

As James says, buying just what you need is best, especially as small taps and dies are very expensive. A cheapo set from Machine Mart (040219154) will set you back £38 - this does have an M1.8 as it happens.

Now the really difficult thing is using them!

Taps come in pairs and you should use the pointier one first.

As James says, they need lubricating. I find oil best as waxes tend to glue the swarf into the threads. Rotate the tap or die slowly up to a quarter turn then rotate it back that same distance. This cuts the swarf into the grooves and helps spread the lubricant onto the next piece. Make up the quarter turn you lost and progress a further quarter turn before backing it off... and so on. This is slow and tedious but always works.

Sometimes, with the right clearances and lubricant you can skip all the reverses... but then one day the tap breaks off and you glumly promise yourself you won't do that again as you try to get the broken bits out...

After using the pointy one, remove it and run the less pointy one through - you won't need to do the backing off this time with such small sizes. This sets the size correctly where the pointy one is sized for making the first cut.

Threading the screw piece is basically just the same. You don't often get adjustable dies at this size so that's less to worry about. If you have two dies supplied as a pair, use the one with the bigger hole or indentation first... but I think it's pretty unusual to make pairs at this size. Again progress slowly and reverse at least 1/4 every turn.

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Thank you Joe
1.55 is waht Cooksons say is the internal diameter of tube that looks like it will do what I want but maybe I might not even have chosen the best tube. Maybe the walls dont need to be so think to put a screw thread in?
What I'm trying to do is make a ring with a tube standing where the setting would be. The outside diameter of this tube to be wide enough to take one of the popular charm beads approx 4mm. I looked at whats available and cooksons thick walled jointing tube looked the best choice as external is 3.95 and internal 1.55 but if you have a better suggestion that also makes the tap an easier choice that would be fab. If I then made a screw that fitted inside the tube with a nice setting on top I could interchange the beads without affecting the internal diameter of the ring
Thank you for your help, very much appreciated
Helen

Quote:

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Originally Posted by Dennis

Dear Helen,
Adding to what James and Joe have said, a big problem when cutting threads is to avoid wobble which makes for a loose fit. So I clamp the tube horizontally in a grooved vice to avoid distorting it and hold the tap in a pin vice, so that I can turn it with a supported hand. For the screw, I clamp the die and introduce the wire with a pin vice held horizontally as before.
kind regards, Dennis.

a postscript, silver screws are ok as a permanent cold connection, particularly with a little adhesive added, but quickly become slack when undone a few times. D.

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Hi Dennis and thank you
Maybe what you are saying will mean that what I'm attempting wont actually work. I wanted the screws to be done and undone to create an interchangable ring and other things. I'm working in silver but if the screws become slack it sort of removes the benefit altogether. Is there an alternative nut and bolt ready made that I could buy and maybe solder inside my tube and on the end of the head instead of making weak screw threads myself?
I very much appreciate your help
Thanks
Helen

Quote:

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Originally Posted by Shaun750

I can't find it now,but there are some online video from MIT of basic engineering workshop practice.It has a section on using taps and dies. They will help anyone who is starting to make jewellery in a few areas,of understanding drilling,and if you have a lathe or drill press.

I never really measure anything,just find the one that fits. Remember to turn the tap back every few turns to break the swarf off now and again,that's what causes them to break.

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Thank you Shaun
I will have a little earch on the web. Its starting to look like maybe cutting screw threads wont work for this project but I can see a million other uses so intend to learn to use the tap and die set (or rather whats left of them after I broke one!)
Thanks
Helen

[Quote: is there an alternative] Yes, nine carat white gold tube and wire, which can be soldered with silver solder and would match well enough. It would add to the cost, but not horrendously in small quantities. Even so, if I were making it for sale I would test drive it first.

I also think you could use 2.0 mm metric stainless steel bolts (they call them machine screws), with the heads cut off and matching nuts instead of tubes. They have them at Clerkenwell Screws. If you buy screws long enough, each one would do for two items. They can be soldered with silver solder and Tenacity 5 flux, but if you use easy solder you might have to use easy flux with a pinch of Tenacity 5. The only remaining problem is that after heating they might not polish very bright but they would certainly work well.

When working on the problem of interchangeable bezels some time back, I found it very important to centre all the components perfectly or the results will look decidedly off.
Kind regards, Dennis.

I also think you could use 2.0 mm metric stainless steel bolts (they call them machine screws), with the heads cut off and matching nuts instead of tubes. They have them at Clerkenwell Screws.

I tried google but couldnt find them on line so will phone tomorrow and get a few to play with. Thanks again and also for the tip on centering though that will probably fox me too!
Thanks
Helen

Quote:

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Originally Posted by Enchanted Cobwebs

Maybe the walls dont need to be so think to put a screw thread in?

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It all comes down to a horrible table of numbers (Thread Sizes) and a rough rule of thumb, diameter should be twice hole size.

If you moved up to M2 - a cheap and commonly available size - you'd need an internal tube diameter of 1.6mm. the advisory nut diameter is twice the screw diameter, so 4mm - near enough to the 3.95 from cooksons, so you could reasonably happily drill out your little sections of tube with a 1.6mm drill, then tap them with a 2mm tap and consider them reasonably robust.

As Dennis says, silver is a very soft material for this sort of thing, so you must maintain as much material as possible by choosing sizes carefully or you'll end up with just a tiny amount of silver overlapping in the threads and it won't take long for that to wear and the screw to stop working. For the same reason, you should cut the threads carefully so as not to cut away more material than necessary.

I can't see any appropriate sizes in the Cookson white-gold range. I suppose you could work from wire and drill the hole yourself... but £28 for 1cm of 4mm doesn't sound ideal for this, even when buying minimal amounts!

Since you've got the silver tube, I'd have a go at drilling with a 1.6mm drill and tapping M2 and trying it out!

I apologize for bump the old topic, but I have some interesting observations that I would like to share, maybe this will help someone in the future because once I was on the lookout for useful advice.
or tapping holes First you must use the proper size drill,for that you referance your handy chart http://www.brokenbolt.com/images/sta...-tap-drill.pdf

For example a 1/4-20 requires a #7 drill,but you can also use a #6 or a #5 thread strength is still there and its easier on the tap,any bigger than that and you lose too much thread strength.

Drill hole straight,preferably using a mill or drill press,can be done by hand,then lube up tap making sure it stays straight and go to town,thread it in and backoff and clear chips as you go especially in a blind hole or deep thru hole.

A die is used for cutting new threads,can be used to clean up threads as well. Most tap and die sets you find around are carbon steel which arent that great(depending on the threaded material) but if you dont use them often work just fine. HSS is preferred but you will pay more best for sizes you use most,as with taps make sure to use some cutting oil.

To fix stripped threads you need Helicoil(thread repair kit) kits https://mechanicguides.com/best-tap-and-die-set/ of the proper size,they come with what you need. just dont try and use the helicoil tap also known as an STI tap to tap your regular holes or you will be hosed. Also you can redrill and retap to a larger size if possible.

Here's a vid i found on youtube for you:

https://youtu.be/KVnN4jiB7Gk

All that would be great a) if we worked in Imperial that much any more over here (thankfully selecting the correct tap & drill is much easier with Metric) and b) if we wanted to repair a stripped hole in, say, an engine block (which brings in the issue of maintaining a straight hole). Doesn't really have a huge amount of relevance to jewellery.

Carbon steel taps are fine for softer metals in small section.