Making a die to match a tap?

[mChavez]

Hi All,

I'd like to take a bash at a kitless pen, and I'd welcome your thoughts about whether it's possible to make a die to match a tap using just hand tools? If one was to acquire a double-lead tap without a matching die, is it a reasonably straightforward job to tap a die for it?
My thoughts are as follows:
- the die does not need to be particularly hard, as it will only be cutting acrylics and ebonite (well, probably afri blackwood too, if I'm feeling particularly brave. I've threaded it before and it's OK. More concerns with dimensional stability compared to plastics though), so unhardened silver/mild steel, or even brass (?) might be sufficient?
- Take a length of brass/mild steel/silver steel square bar
- drill a slightly undersized hole in the middle of the bar
- Ream it out with a tapered reamer, so one end is a bit bigger than the other. I'm sure I have a couple adjustable jobbies rusting away in a far corner of the toolbox.
- Tap the thread with the hypothetical tap
- cut slots across the threads with a junior hacksaw, or file them with a small hand file, whatever I find in the toolbox that fits into the M12-ish size hole.

Brass is probably the easiest material to work with, while silver steel will last longer (is that even a consideration for a beginner hobby pen maker with no intention to turn volumes?). I'm reasonably comfortable working metal by hand, but I am hopeless at machining it, even if it only involves drilling a hole. Brass should be more forgiving, while silver steel is likely to work harden on me.

Am I being too daft & simple here, or is it a valid option? On the surface it looks like an hour's job in the workshop. Has anyone done something like this?

Thank you.

 

[geordie0928]

I wsh to do some of these kitless pens, but when you look around for kit you need you need deep pocketd to get you going. Any idia for someone else will help us both.

 

[mChavez]

...How much of that pro-level kit do you need though? Fair enough if you want to turn them fast for profit and you need 99% accuracy, then it's worth investing in the right high quality tools. But if you're happy to take things slow, adapt/make some tools yourself and happy to accept 90% accuracy while you're learning, I think I might get away with my basic old lathe & chuck.

I've only turned half a dozen slimlines so far, so I'm very new to pen turning so I'm probably being too naive.

Don't know if you've seen this article. Some food for thought.

Crafting a Kitless Ebonite Rollerball Pen with Simple Tools

Learn how to make a kitless rollerball pen from Ebonite using basic tools. Affordable, straightforward steps for DIY enthusiasts. Perfect for beginners!

woodworkersinstitute.com

 

[flexi]

A great article, from the late great Walter Hall...thank you for the memory!

 

[Curly]

The issue I see is that when you make a die from the tap you cut a thread with no clearance, meaning the fit is too tight. You need some clearance to allow the parts to fit together, that's why commercial threads are cut to different classes of fit to facilitate the use of the thread. The die cuts a smaller thread than the tap. Loose fit on coarse threaded bolts holding tractors and cars together and closer fits for where precision is needed like a micrometer or a camera lens. You can try it but may not have the success you are hoping for. You also need to account for the material deformation while threading and the resulting spring back and the parts not fitting at all.

My suggestion is to get metric single start taps and dies in the sizes and pitches the multi-start taps and dies have and play with them long enough to know what sizes you want to settle on. 12mm,13mm,14mm etc. The drill bits for them will be the same as the multi's. They are relatively inexpensive and you can get on with the fun part, making pens and not tooling. You only need the multi-start stuff for the cap to barrel thread. All the rest can be standard single start threads. That only leaves the fountain pen feed threads which are specific to each nib size and brand. Not a concern if making rollerballs.

Pete

 

[Paul-H]

My advice, if you are just starting is to forget about multi start taps and dies and just go with standard fine pitch taps, something around 12 x 08, 13 x 08 or 14 x 08. Then once you have made a few and have convinced yourself you must do multi start then you can invest in the exorbitant prices charged for multi start taps. £200 plus just 1 tap and die is exorbitant (to me ) especially if you buy a small batch from the American maker they are said to be about £65 each, don't know how many makes a batch though, I know it's been done a few times on the American pen makers forum.

Perhaps it's something that could be done this side of the pond, they get them from TAPCO iirc

 

[Curly]

There is a member that was selling triple start taps and dies among others needed for pens made in China. They were a lot cheaper than the ones made by Tapco. You could try messaging him to see if he still has any to sell, assuming you don't have any strong feelings about such things.

https://www.penturners.org/members/jick-wu.41553/

 

[Curly]

My advice, if you are just starting is to forget about multi start taps and dies and just go with standard fine pitch taps, something around 12 x 08, 13 x 08 or 14 x 08. Then once you have made a few and have convinced yourself you must do multi start then you can invest in the exorbitant prices charged for multi start taps. £200 plus just 1 tap and die is exorbitant (to me ) especially if you buy a small batch from the American maker they are said to be about £65 each, don't know how many makes a batch though, I know it's been done a few times on the American pen makers forum.

Perhaps it's something that could be done this side of the pond, they get them from TAPCO iirc

From past buys the quantity price breaks start at 3, 6, 9, 12, with 24 being the last.

 

[mChavez]

Ok, I see. So the tap cuts the home-made die that's going to be bigger, than "proper" die. When I use it to cut the new male, it's going to be an oversized male, that will have real trouble fitting inside a "normal" female.
I wonder if a bit of good old in-out-in-out with the tap will loosen the female enough to accommodate the larger-than-average male.

I'll get my coat.

 

[Curly]

Man the open time for editing a post is short!
I wanted to edit my post #7 to say that jick wu is a member of the IAP, not this forum.

Now someone grab that guy leaving with his coat and cuff him one.

Pete

 

[mChavez]

Last post made in 2022 on IAP...

I'm going to try the home-made die method, just to see if there's any potential. We're only talking about a couple treads, so if things don't fit from the start, a kiss with a jeweller's file over the threads will probably resolve any fitting issues.

My idea is to go with an M10 cap and make a custom slimline for a cross refill.
M10 cap runs a ~9mm minor, so I have 9-1-1=7mm for the barrel joint. M7 runs a ~6mm minor which is enough for the cross refill to go in, and
Section works out as 8=>9mm, which is probably the lowest range of "slim".

I think I've made some decent theoretical progress since I've turned my first kit a week ago

Oh, and I hope that I can turn acryllics and ebonite with carbide tools?

 

[Curly]

His last post may have been made a couple years ago but if you look at his profile he was logged in on the 23rd of last month. Still around.

I've found if you turn the ebonite at lower speeds the tool edges will last longer between sharpening/replacement. The Acrylics can usually be turned at whatever speeds make you happy.

Pete

 

[Dalboy]

Making a die is not so simple. Ideally silver steel is best which can be hardened and then tempered. A double start thread would need the use of a decent metal working lathe as well as a very small internal threading tool which could easily break. Not something that I would even attempt, as I am only a novice at metalworking. If you are serious then look at buying one as mentioned by others, look around to see if you can get a cheaper one.
Have a look at Screwcutting in the lathe from the workshop series. There is a section on multi start threads.
Worth looking or contacting Tracy Tools ltd even if they don't show them they maybe able to help

 

[alpha1]

You dont need to use triple lead taps and dies while you are learning just use cheap single lead taps and dies.

 

[mChavez]

Thanks. I don't have a metalworking lathe (or the skills), so turning a die is not an option for me.
It looks like it's possible to buy orphaned 2- and 3- lead taps on ebay on the cheap, so there's a possible home-made die bodge.
I can see all of the engineers cringing at the thought, but this is not rocket science. Unless you're making a fountain pen that will work in space in zero gravity. I am a woodworker, so I just don't have the engineering mindset. All it needs to do is keep the pen lid on.

Another option is to embrace the 21st century and get a few sets CNC-machined. I've done a quick price quote on a regular M12 tap model and I expect just under £100 per tap+die set, if I order 10 sets in the same size. I can probably design the tap & die after watching some youtube videos but unfortunately, I can't just get one prototype turned, so I don't think this is worth the risk.

 

[ValleyBoy]

I admire your ambition and wouldn’t want to dissuade you from trying so give it a go and let us know how you get on.

Some potential issues have already been mentioned which you should keep in mind, but if this is just an exercise in trying it out then part of the fun of doing it is discovering the issues and finding a way around them. You’ll certainly learn a lot.

All I will say is you’re right that it isn’t rocket science, but it’s certainly harder than it sounds.

If I was going to mention one thing you should pay specific attention to it is when you drill and tap the hole in the die. You need to make sure it is accurately centred and completely perpendicular to the faces, (front and back), and also parallel to the outer sides. Concentricity is important and will matter if you’re using a die holder to thread the pen. For this 90% good enough is outside tolerance (depending how we’re defining 90% but even a tiny angle is too much). If this isn’t spot on when using on acrylics, especially for finer pitched threads, then you will just mash up the threads as you’re twisting the die on and you’ll find it will start to get very hard to twist. Constantly stripping threads off your freshly turned tenon will get annoying very quickly, (trust me), so it’s worth getting this aspect as perfect as you can.

Anyway good luck with it. I’m genuinely interested to hear how it goes.

Cheers
Ash

 

[mChavez]

Concentricity is important

Thank you very much. I'm not much of a turner to be honest, and the only more or less serious turning that I've done to date were chess sets. I only have a clapped-out Record DML24 that I originally bought from my neighbour when he was moving, so I could turn custom chisel handles for myself (I'm damn picky about the size & shape).
So, unfortunately, well aware of the concentricity issue, and well aware that, realistically, my gear is not quite up to scratch, even if the die was perfect. Which is one of the reasons I'm not jumping at buying a £250 tap & die set.
I'll accept on off-centre pen for the first few attempts - for learning, getting something done is a lot more important that getting something done perfectly.

This is some food for thought though: making the die so that it would be easier to align the thread to the sides.

 

[mChavez]

Fwiw, apart from the used multi-lead taps in random sizes from the US, one can source the following TR taps new on ebay from China. All of them are for threading nuts to go on 3D printer lead screws, and none of them ever come with a matching die (I've asked the sellers).

TR10x2(P1). That is 10mm OD, double-lead, with each thread having 1mm pitch.
TR14x2(P1).
TR12x4(P2) - Double lead with 2mm pitch eaches.
TR12x6(P2) & TR14x6(P2)- triple-lead with each thread at 2mm pitch.

There's also a TRx3(P2) listed by two sellers, which is not a valid thread. It has to be either TRx3(P1.5) or TRx4(P2).

For some reason, no TR12x2(P1) and no multi-lead options for TR11 or TR13.

They call them "Double (Three-) head taps" in the listings.

I've ordered the TR10x2(P1) as it was the cheapest (Not exactly pocket change. £28 taxed & delivered. I'll skip my morning coffees next week), just to see what it's like and whether I can make any use out of it. I guess, I can always re-sell it to some 3d-printing enthusiast if it does not work out.

Will let you know how I get on.

PS By the way, I'm well aware that good tools only make you cry once - when you buy them - but I also like to try and beat the system if I get a chance.

 

[mChavez]

In regard to thread concentricity, here's a thought: if you need to thread, say, a 5mm tenon, then can you take a slightly longer blank, get a 10mm tenon and turn the leading 5mm to the minor of the die, so that it just slides over it? This way once it starts engaging the larger diameter of the "real" tenon, I'd hope that the "leading" tenon will prevent it from wobbling and cutting off-parallel to the walls? Once threaded, the leading bit can be parted? In this case it shouldn't matter if the die is perfectly aligned - it has the cutting surfaces referenced against the blank.

Just hypothesizing while I'm waiting for some acryllic blanks to play with.

 

[Phil Dart]

The best advice has already been mentioned a few times - perfect your designs and your methods with cheap single start taps and dies. You can invest in the triple starts once you are confident that a) you know what size is best for your design, and b) you are sure that the amount of use they will get will warrent the expense.

The problem you will have with contructiing your own die with a tap has also been mentioned, but I will explain it in a slightly different way:
If you drill a hole of say, precicely 12mm, and try to push into it a rod of precicely 12mm, it will not fit. I know that sounds daft, but the edges of both are identical whereas the edge of the hole needs to be at least slightly bigger in order to get the rod in. If you now thread that hole with a tap in order to make a die, then thread the rod with the die you've just cut, the same problem exists - every single interacting surface of both threads will be identical in size. The extent to which the female needs to be larger than the male will depend on the application - NASA might demand a closer tollerance than the pen maker, but the fact remains that it has to be larger or it won't work.

Having said that, if you intend to experiment, there will be a lot of work involved to make the two fit together, but the burden is lessened a little once you realise that normally it is not the female that is bigger than the male, it is the male that is smaller than the female, which is not quite the same thing. In other words, a female 12mm thread is normally 12mm, whereas a male 12mm thread is slightly less than 12mm, which you can prove for yourself by measuring the diameter of any bolt that happens to be knocking around your workshop. The good new then, is that judicious use of files and other abrasives on the male in order to make it fit, will be a lot easier than trying to do the same thing on the female.