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This is a short Hidi ( how
I do it ) on how I make some screws and a
small bearing housing for a spinning ring. A Hidi on how to make a
complete spinning ring can be found
here. I
order the bearings from SMB bearings in the UK at
http://www.smbbearings.com. In this Hidi I am using a
bearing with a 6mm flange and a 5mm diameter and a bore of
2mm. If you go check out SMB's website, they got all the
schematics of the various type of bearing available.
I
start this Hidi with the screw making part first. I use only
bench tools, no lathes or milling machines.
I bought a tap and die set from Rio Grande. It is quite
nice, adequate for the job and costs about $115.
The only thing is that you only get one tap per hole and a
replacement set costs $50, which is a little mean.
I thread the wire into the 1.2mm hole. The diameter of the
wire can be thinner or thicker, but I use 1.2mm because then
my pilot hole for the tap is 1mm,( in 18kt gold) and that is a standard
drill. Notice how the wire has twisted. That is because I
use the maximum thickness I can for that hole. That way
makes sure the threads are fully formed. If you use to thin wire,
it threads easy, but the threads are not fully formed. This
will not allow you to tighten the screw adequately, and the thread will
tend strip easier.
After there is enough thread, I cut the wire as shown. These
are going to be short screws.
Then I take my torch and melt the unthreaded part into a
little ball.
This is a close-up of a piece of mild steel
plate that I have
drilled a hole through, and then used a 2mm ball frazer, (
in this case) to make a domed indentation. The center hole is
slightly larger than the diameter of the thread.
The threaded and balled piece of wire is inserted into the
steel plate.
The little ball is hammered down in to the cavity. This
forms the screw head to the desired shape. This shape is
rounded, in this case, but is not necessarily the only shape
possible. A barrel frazer or a cone burr will form a flat
headed or a tapered screw head shape respectively. The
hammering also work hardens the head, which is essential for
screwing something down tightly without harming the screw
slot.
Then I file and sand the the top flush with the steel plate.
And I pop it out from the other side.
Then I cut the screw slot , in this case with a 3/0 saw
blade, but of course this can be varied to what ever width
is needed with a thicker or thinner blade. Then I re-tap the
screw, so as to get the thread as close as possible to the
head.
Here is the screw, 2.5mm long, semi finished.
Although the pictures below
show the screw standing very proud, it is quite easy to make
them flush. The bearing housing described below is a stand
alone one, that is, it is not an integral part of a
jewellery piece. Once the ring is designed and made, it will
be soldered in place.
The
Bearing Housing.
These are flanged bearings. I like using them, but of
course, any other bearing can be used. It just depends on
your design, really. I use a bore of 2mm as the minimum for
a spinning ring.
I make a tube the same
diameter as the flange. The wall thickness is 1mm. Then I
drill out a 5mm recess so that the body of the bearing fits
inside and the flange rests on top. I did not have a 5mm
barrel frazer, so I modified a 5mm ball frazer, and it
worked very nicely. A farmer makes a plan, as they say....
The height of the tube
allows me to drill and tap a screw hole without touching it
body of the bearing inside. The closer the tolerances, the
lower the bearing.
Then I make the outer housing, into which the flange tube
will fit. This is simply a tube of the right diameter and a
plate soldered on top.
Like this. This clamps the bearing flange between the outer
housing and the flange housing. Then I drill a hole through
both sides of the housings, and tap the inner flange housing
with a 1.2mm tap. The outer housing hole is enlarged so the
thread of the screw can pass easily through. Again, notice
the relatively large bore (center hole) of the bearing in
relation to it's overall diameter. This makes for a strong
center shaft.
Here the two housings are screwed together. Although the
screw looks large in the picture, it is only 2mm in
diameter. I leave it proud like this, because this housing
is going to be fitted into a tourmaline and diamond cluster,
so the screw will be inserted and removed many times. This
will wear the head, so I leave enough material to
accommodate that.
This is the center screw. Even though the housing is made
out of 18kt yellow gold, I make the center screw out of 14kt
gold. This is because 14kt is much harder and stronger than
18kt gold. This screw is not made like the small housing
screws. Rather, the top is soldered onto the shaft after it
is threaded. I have left the solder visible under the head
for the picture.
Here the center shaft is inserted through the bore of the
bearing. The center washer stands slightly proud of the
outer bearing casing, because when the cluster affair is
screwed on, it must not touch the outer casing. If it did,
it would not spin easily. It is 7.7mm in diameter.
And 4.5mm high.
All the separate components. Manufacturing time is about 5
hours. Weight of gold, 2.5 grams.
This is certainly not the only way to make a standard
bearing housing. I would love to here of different methods,
should someone know of some. The screws and bearing housing are used in
Making a
Spinning Ring.
If you have any questions or wish to be notified of any new tutorials that are posted,
email me at hansmeevis.tutorials@gmail.com |
