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Making a ring mandrel- jewellery tooling

What is the taper?

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OldMetaller19/09/2016 08:00:22
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149 forum posts
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Good morning everyone, I have just rashly promised my girlfriend that not only will we get engaged, but also that I will MAKE her a ring!

I have read up on ring-making, and know that I need a ring mandrel. Being a tightwad, I want to make one out of a steel round bar offcut.

My problem is, I need to know what, in degrees, is the taper I need to cut on the bar, given that the ones I have looked at have a working length of 200mm which tapers from 25mm to 10mm?

I know that somebody on here will know how to work this out, sadly my skill with numbers is non-existent.

As a bonus, if somebody could tell me the ID's of the various ring sizes I would be able to groove the mandrel appropriately.

Over to the vast body of knowledge and information that I know to be present on this forum!

Thanks in anticipation,

John.

Les Jones 119/09/2016 08:23:17
2092 forum posts
144 photos

Hi John,
If you dig out your maths notes from school from when you were about 13 they should refresh your memory of trigonometry. As the difference in the small and large diameters is 15mm (25 - 15) then the right angle triangle formed between a line perpendicular to the large end that meets the small end will have one side 200mm long and the other 7.5mm long (15/2) . So now you know that the tangent of the angle is 7.5/200 = 0.0375 As you know the tangent you can find the angle from log tables (If they were still used when you wnt to school.) or us a scientific calculator to find the angle. You will find that the angle whose tangent is 0.0375 is 2.15 degrees. This is the angle between the axis and one side. The included angle will be twice this which is 4.3 degrees.

Les.

JasonB19/09/2016 08:26:22
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16051 forum posts
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The included angle is 4.3degrees so either set your topslide over to 2.15degrees or offset the tailstock which would allow you to cut the taper in one long pass, you will need to offset enough to move the tailstock end of the work 7.5mm closer to you, thats if you need to make a full length one.

ring.jpg

Edited By JasonB on 19/09/2016 08:29:34

JohnF19/09/2016 09:10:43
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853 forum posts
102 photos

John, have a look at the link below for sizes, quite a bit of info. Regards John

**LINK**

not done it yet19/09/2016 09:19:13
3248 forum posts
11 photos

Here is a simple solution to your problem.

All you need is a ring which already fits her finger. Use it as a comparator. You can then make a short guage at any angle you desire, marking it at the point where her current ring fits.

Chris Evans 619/09/2016 09:42:32
1451 forum posts

This brings back memories of making rings from 2 shilling coins. I still have the little jig somewhere that has a vee shape milled in it with a shallow angled dovetail cutter. The coin was then held by hand in the vee and gently hammered to roll the outer so that the writing on the coin was readable from inside the ring. Sizes where taken from a ring that fitted the girl. At the correct inner size the hammering stopped the ring put in the lathe and bored to suit ring size the on a mandrel to form the outer. Polished up they looked nice. Early coins with more silver content where used. One girl I made a ring for had big fingers which meant using a half crown coin to get the size.

Good luck with the ring making. Chris.

KWIL19/09/2016 09:45:12
3111 forum posts
56 photos

Try this,

**LINK**

Speedy Builder519/09/2016 10:51:25
1801 forum posts
127 photos

For a one off, use a morse taper. Fingers are tapered, but I never heard of a standard for fingers.
BobH

KWIL19/09/2016 12:06:37
3111 forum posts
56 photos

BobH

The are standard sizes for rings, generally L - W, with suitable gauges to test fingers (and knuckels) for size.

AndyP19/09/2016 12:14:15
188 forum posts
30 photos

Congratulations! Some random thoughts:-

A 2 morse taper covers UK ring sizes G to Q roughly so the most common ladies finger sizes.
A plastic cable tie makes a good finger gauge.
If you do make one a gentle taper is easier to work on - you only need one size after all.
Get a good finish on the taper because that will be the finish on the inside of the ring.
Leather or plastic hammers are great for stretching and won't mar the ring material.

The best thing about working with precious metals - if at first you don't succeed just melt it and start again!

Andy

Neil Wyatt19/09/2016 12:51:57
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16446 forum posts
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A fiend of mine went on a 'make your own wedding ring' course. he was very pleased with the result.

Neil

Neil Lickfold19/09/2016 13:34:53
562 forum posts
102 photos

If you have a lathe, just make a couple of form tools and turn up the ring to the profile and diameter that you want. I made my wife a Titanium wedding band for our 15th anniversary . I made a form tool for the inner shape and a form tool for the outer shape, parted it off. Then set it onto a mandrel and blended the side that was parted off. To get the size I just asked her to take a ring to the jeweller in town and got the sizing off them. They told her how many mm diameter it was.

Neil

OldMetaller20/09/2016 07:06:08
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149 forum posts
14 photos

Gentlemen, thank you for the wealth of information and ideas you have presented, I knew you wouldn't let me down! Thanks BobH, I'm really pleased to hear that a 2MT mandrel will suffice as I have a couple of these in my 'lathe tooling' box, doing nothing.

Les Jones 1 and Jason B, thank you for the very detailed and specific info, I still don't pretend to understand the maths but at least I know what to do now!

AndyP, I'd better not get the cable ties out, last time I did that she phoned the police! wink

Once again, thank you all very much.

Regards,

John.

Sam Longley 120/09/2016 07:35:06
719 forum posts
26 photos
Posted by Chris Evans 6 on 19/09/2016 09:42:32:

This brings back memories of making rings from 2 shilling coins. I still have the little jig somewhere that has a vee shape milled in it with a shallow angled dovetail cutter. The coin was then held by hand in the vee and gently hammered to roll the outer so that the writing on the coin was readable from inside the ring. Sizes where taken from a ring that fitted the girl. At the correct inner size the hammering stopped the ring put in the lathe and bored to suit ring size the on a mandrel to form the outer. Polished up they looked nice. Early coins with more silver content where used. One girl I made a ring for had big fingers which meant using a half crown coin to get the size.

Good luck with the ring making. Chris.

How many times did you get engaged you cheep romeo?

Hope you did not marry the one with the big fingers -- never bodes well for the future frown

Sam Longley 120/09/2016 07:36:39
719 forum posts
26 photos
Posted by Neil Wyatt on 19/09/2016 12:51:57:

A fiend of mine went on a 'make your own wedding ring' course. he was very pleased with the result.

Neil

Cannot have been that good --- sounds as if he ended up married !!!!!!

Edited By Sam Longley 1 on 20/09/2016 07:37:38

Chris Evans 620/09/2016 07:43:17
1451 forum posts

Sam, I married a skinny one from Northern Ireland that I met in Spain. Still together after 44 years.

The rings I made where a bit of a fun thing for a few girls that worked where I served my toolmaking apprenticeship and a few other friends. I did make my wife one but she lost it, hers turned out a bit wide to get down to the skinny size. 5/8" diameter from memory.

Gary Wooding20/09/2016 08:12:11
572 forum posts
137 photos

With over 55 years experience as a goldsmith I can assure you that there is no standard taper for a ring triblet. Choose anything that's handy and covers the size you need.

In UK, ring sizes are denoted by the letters A (smallest) to Z (largest), with very nearly 1/64" (actually 0.992/64" between one size and the next. Conveniently, size C has an internal diameter of 0.5060", which is near enough 1/2", and size Z is 0.8625" which is near enough 55/64".

You haven't said what materials you will use for the ring - what metal, what stone(s) etc. Your post suggests you will make the engagement ring.

If this is your first ring I would strongly recommend practising before making the real one, especially if you intend setting stones.

Please report back on your progress.

 

Edited By Gary Wooding on 20/09/2016 08:14:52

davidk20/09/2016 09:08:45
44 forum posts

Surely if only making the one ring, you don't need a full length ring triblet, you could use a Stub Mandrel...

Gary Wooding20/09/2016 09:42:34
572 forum posts
137 photos
Posted by davidk on 20/09/2016 09:08:45:

Surely if only making the one ring, you don't need a full length ring triblet, you could use a Stub Mandrel...

Absolutely! I'm sure Neil would agree.

(I added the dimensions to indicate what sort of precision is required.)

Sam Longley 120/09/2016 10:44:52
719 forum posts
26 photos
Posted by Chris Evans 6 on 20/09/2016 07:43:17:

Sam, I married a skinny one from Northern Ireland that I met in Spain. Still together after 44 years.

The rings I made where a bit of a fun thing for a few girls that worked where I served my toolmaking apprenticeship and a few other friends. I did make my wife one but she lost it, hers turned out a bit wide to get down to the skinny size. 5/8" diameter from memory.

Do they take long to make ??

My wife reminded me this morning- as she went to golf- that I have forgotten out 47Th wedding anniversary ( for about the 45th year in a row) can one make one in the time it takes to play 18 holes , allowing for a few sliced shots & a cup of tea afterwards

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