How many members are using the Chinese Faceting machines?

[Faceting Frank]

I don’t know how accurate my 45deg holder is either RC. But I do know the hole for the dop is 90deg to the bottom flat surface of the holder, because once I have the 45deg holder set, it will cut the table accurately relevant to the facets on the crown.

[MakkyBrown]

I am tempted to grind my 45 degree on a my machine to get it spot on. But then it is just like all the other inaccuracies I tend to ignore.

[Faceting Frank]

It doesn't need to be 45deg. It could be 40deg or 50deg, anything around 45deg would do. It only exists because you can't cut the table without one. It's the hole for the dop that matters, it has to be 90deg to the bottom flat surface.

[Ghost]

This depends on the relationship of the hole to the 45 degree dop's sharft , and the shaft's position in the handpiece.
If you use 'keyed' dops, then the key has to be spot on as well.
if the dops are not 'keyed', then instead of using the bottom of the 45 degree dop, you could use a testing dop with a large flat base and exactly vertical shaft each time you set up for the table.
The 45 degree adapter can be any shape, even spherical provided the hole, shaft and key are correctly aligned.

Ghost

[Rusted]

"you could use a testing dop with a large flat base" That's what I had when I had a Gemmasta, about2.5 inches across, turned out of an old solid brass door knob. It allowed me to get it nice and accurate. Incidentally the angle on my 45 degree dop was close to 46

[Faceting Frank]

My original comment about the 45 deg dop holder not needing to be 45 deg came from the picture in JBK’s reply 18. As you can see, he just needs to lower the faceting head till the holder is flat on the table, but the hole for the dop must be 90 deg to that flat surface.
Maintain that angle with the hard stop and raise the faceting head up high enough to fit the dopped stone.
So, you could make the dop holder with the angled dop any angle you like, 30, 40, 50, 60 deg, as long as you have a flat surface to align up with the lap.
I have made machines in the past with keyed dops, this does set the index position, but not the angle of the quill.

[JBK]

Ah yes, gents. Thank you managed to align the table dop straight.

[JBK]

Mind you, when aligning the bearings blocks on which the quill sits it made the sensor to be in a different position and the the life of me I could not get the digital readout to be exact every 10 degrees. I don’t know if it was accurate to start of but I’m getting about 0.3 or 0.4 degree runout now.

[JBK]

[JBK]

Side to side motion is now acceptable i think.

[JBK]

What affects this digital reader?  (I have parked this project for a little while - ....) No haven't got it right yet

[1] the adjustment of bearing blocks (a screw on that holds it)
[2] the two screws that hold the reader to the yolk also have affect on the angles
[3] my level box that i was using to double check the reader - if too close it changes the angles of the reader
[4] the mast - fixed
[5] had to put two non metal washers in the quill that sits in the bearing block- if there is any side movement it also affect the reader by 0.2.-0.4 degree.
[6] opened the reader but it does not seem to have any adjustments , the magnet is build into the quill

yes- i did have have a few words with the machine along the way...

[JBK]

Yes, Frank- the quill was also of centre (1.5 degree) hence what caused me to play with the bearing blocks and by doing that it slightly moved the sensor on the reader.

[JBK]

[Faceting Frank]

The two slots that the quill assembly pivots on must be set so the quill is parallel with the mast, as shown in the drawing. If one it to high or to far back or forward compared to the other it will tip the quill off line. As in the red dotted line on the drawing. You cannot measure this in anyway, but can only see it by eye when the quill is pointing down, looking from the end of the machine.

[JBK]

True, if the above is not straight then the cutting angles from the index wheel will be all over the place.


Thanks for the pointer