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Topics - FlashGP

Pages: [1] 2 3
1
Gemstone Faceting / Prototype Concave Cutter
« on: January 02, 2019, 05:21:39 PM »
I finally finished my budget concave cutter.  I have embedded links to photos in the Gallery.  click on the link to view them.
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9017

I don't have a lathe or mill so designed the cutter to be adjusted in the y Axis (the mast moves in the X axis).  There's 25mm of play each side of centre.  This means that I can cut parallel lines on the side of a step cut by moving the mast out of alignment for cuts other than the first.  The adjuster thread advances 2mm per turn. I used anti backlash nuts on the threads to remove the slop in them.

The parts cost me between $450 and $500 to make, before cutting mandrels.  I used linear bearings to support plywood decks that sit around the platten on my Factron.  I used 4mm T Nuts to pressed into the Ply as ancker points, although the lower bearings and alignment screw are sitting on 3mm angle aluminium. 

I made the arm on the oscillator motor from a piece of 10mm square mild steel, drilled, tapped and cut down.  3 taps at 10mm, 15mm and 20mm from the centre means that I can adjust the throw on the oscillator between 20mm and 40mm to accommodate different mandrel sizes.  The link is two tie rod ends for CNC Cuters, one male and one female.
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9020

I bought a cheap Ryobi laser level and Stud Finder at the post Christmas sale.  The laser level throws the laser in a vertical arc so it produces a line on a surface.  Here I'm using it to sight down the middle of the cutting mandrel and shine on the mast.  If the cutter is out of alignment, two lines appear on the mast as in the picture, as the cutter is brought into alignment they merge into one bright line.  I'm pretty sure this has something to do with the reflection from the curved surface of the mast.  Once the mast is aligned, the Quill is lowered and the Quill Stop adjusted until the laser is shining down the centre of the Quill.
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9021
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9025

I used a 25 amp switch mode supply with 2 10 amp pulse width modulators for speed control of the cutting motor and the oscillator drive.  I only needed a 10 amp supply, but the price difference means was small and I can use the Power supply to drive larger motors in need.  The motors I am using only pull 4 amps between them.

http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9023
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=9024
One of the PWM modules is reversible, it is the one standing on edge, the other cost $3.60 and I am trying it out.  It seems to work OK.  I had to de-solder the Pot on that  module and add 3 signal wires so I could mount it as the box I purchased was a little small.  The resistor in the photo is a 10w 22 ohm power resistor to keep a 1/2 amp current flowing.  This is to stop the power supply going into overvoltage when the motors are turned off.  All up the Power supply cost me almost $100 and  it has the grunt to drive 2 x 90w motors.

2
Hi all, particularly Makky

I have bitten the bullet and bought some linear bearings and motors from Banggood and am going to try my hand at making a prototype reciprocating concave faceting arbour.

I have yet to work out the dop stop, and am thinking of something like the arrangement used by polymetric.

Does anyone know of a local source of precision machine parts for instruments or CNC cutters?

Regards
Gordon.

3
Gemstone Faceting / Gem Cut Studio
« on: September 09, 2018, 07:21:49 AM »
Has anyone tried Rej's Gem Cut Studio yet?  He released it about a week ago at the AFG seminar.

I'm currently playing with the trial version, it's quite different to Gemcad and seems easier to design gems on, especially where you are looking for a specific L/W ratio.

I still have to learn how to read the optimiser.

regards Flash

4
Gemstone Faceting / Spare parts for work lights
« on: April 22, 2018, 10:06:47 PM »
I knocked over the work light I use for faceting.  It's a daylight bulb with 4 parallel tubes that clicks into a fitting in the head of the Light stand.  My wife bought it at a craft fair a few years ago.

Bunnings don't stock replacement bulbs so I went to Beacon Lighting.  They suggested I try the internet for an Australian supplier because they have import restrictions on them preventing us binging them into the country.

The bloke behind the counter said that the Greens had managed to get tough new energy efficiency laws introduced that are particularly tough on lights.  In 18 months these green laws will cause him to have to bin 90% of his stock of replacement bulbs if they are not sold by then.

If this is correct I'm amazed that flourexcent lights are on the list as they are more efficient than traditional lights and halogen bulbs.  But i ordered two bulbs on-line in case he is right.

Does anyone know if this is correct?  If it is a lot of people buying these expensive lights at craft shows will be unhappy to know thay can't replace the bulb when it blows.

Regards
Flash 

5
Gemstone Faceting / Am looking for Concave Faceting Design Tips
« on: April 18, 2018, 10:26:42 PM »
I was thinking .... we have computer programmes for predicting brightness in flat facet gemstones, but I doubt there are programmes that do this for concave cuts.

At present it seems a case of try it and see.

Does anyone know of a model or theory for predicting how light behaves when it hits a concave facet?

Or how to set the angle to look good?

regards
Gordon.

6
Gemstone Faceting / where can I buy a fantasy faceting machine
« on: April 11, 2018, 11:19:19 PM »
I have been thinking of buying a concave and/or fantasy faceting machine.

Facetron used to make one that does both but no more.  Ultratech make one for USD5,000 (Fantasy) or USD 4,000 (Concave) depending on model and Poly Metric Instruments makes a concave facetor for USD2,000.

I havent seen any others on the market, but am visiting Clarry fron the Gold Coast to see a couple he has made.  He was making a Gemmaster concave conversion.

I understand that the son of the VJ owners is going to carry on production and possibly make a dedicated VJ concave facetor. 

I have a Facetron so something compatible with it would be nice.

Three nights of searching have only turned up links for US machines and one Indian linkfor a bangle facetor mill.

Surely there are others out there.

Kind regards
Gordon.

7
Gemstone Faceting / Help, does Topaz twin like quartz?
« on: April 06, 2018, 07:28:25 AM »
A few years ago I had trouble polishing quartz.  The 8k prepolish left a mat finish.  I was told at the time it was probably twinned.  I ended up buying lughtning laps to cut and polish it.

I was told it was probably a twinned crystal from Kingsgate.

I have now run into some topaz that behaves the same way.  8k diamond on zinc won't prepolish.  Where the surface starts to shine it seems to crumble away.  It happens on every pavillion facet.

It cant be subsurface damage as I preformed with a 1200 and faceted using 3k on zinc.

The lightning laps and a darkside with Linde A batstick polish, but are hellishly slow.  8k on copper with water almost beats the issue but it scratches badly.

8
Cabbing and More / Stabilising / filling with sodium silicate
« on: March 15, 2018, 08:38:22 AM »
I have heard you can stabilise Aust turquoise with sodium silicate.  I was wondering if sodium silicate could be used to fill or harden soft patches in bolder opal to improve the shine on the polish of the matrix.

Has anyong had experience with sodium silicate

9
Gemstone Faceting / Tips on selecting a cut for a piece of rough.
« on: February 23, 2018, 07:21:33 PM »
At our last AFG meeting one of the new members asked how to work out whether a design would be good for a piece of rough.

Unfortunately with so many variables there is no one right answer.

On thinking further it may be possible to break the problem into smaller pieces, such as if the material is saturated with colour, closed C tourmaline, light in colour, etc.

If we all throw our 2 bobs worth in, somewhere among the answers we may provide answers for beginners or even have a few meaningful discussions.

Here is my first couple of contributions.

Saturated material
I recut one of those commercial red garnets that I chipped when setting it.  The stone was a 10 × 8 and recut as a 6mm round brilliant with conservative pavillion angles of 42 and 44 degrees.  This was my 3rd stone ever. There wasn't enough material for a crown starting at 41degrees so Don Wilkinson had me lower the crown to start at about 38 ou 35 degrees.

The end result was a sparkly red stone nothing like the original dead oval.

Moral of the story.  Cutting a lower pavillion increases the brightness of a saturated stone like garnet and sapphire.

If cutting sapphire optimise pavillion mains angles below 42 degrees but above the critical angle.  This will also help make the stone brighter.

Large reflector facets in the pavillion help increase sparkle.

Jeff Graham's Lighthouse design is good for Fullarton river garnet.

Light stones
Higher crown angles help intensify washed out colours.  Go for a good spread of reflection on the gemray diagram, not necessarily a high spike of light return.  This should help break up the head shaddow and stop the colour being washed out.

Closed C Tourmalines
These are the ones with dark ends.

I'm told these require a step cut with high end angles in the pavillion to stop the light bouncing from end to end.  If light travells from end to end the dark colour kills the reflection or muddies the stone.

Your thoughts?

10
Gemstone Faceting / Hall Mark III Faceting Machine Accessories
« on: February 20, 2018, 10:13:35 PM »
One lapidary club was recently given an old Hall Mark III Facetign machine which hasn't been used in years.  With it was a dop that looks to have been designed to shift the stone off the axis of the dop.  My best guess is that it is a dop for making pear shaped stones.  Does anyone have any ideas on what it is or how it is used?

http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=8800
http://aussielapidaryforum.com/forum/index.php?action=gallery;sa=view;id=8799
http://aussielapidaryforum.com/forum/gallery/8/6695-200218220613.jpeg

11
Gemcad Discussions / Just to get you thinking - Funny L/W Ratio
« on: December 01, 2017, 09:16:01 PM »
Here's a question about the Gemcad Ratios. 

I designed a long rectangle in blue corundum (MM).  it is 5.9mm wide by almost 16mm long.  I dopped the rough at 45 degrees to the horizontal figuring it would force me to rotate the design to suit the stone.  I then rotated the design to give me the correct cutting indexes.

When I went to check how much to leave for the crown, I noticed the ratios were very small, the C/W ratio being 0.013 and P/W being 0.042.   The volume/W ratio was under 0.03 and L/W 1.0.

Anybody care to explain what happened to my stone?

PS. I know the answer, but had to stop and think about it last night.

12
Gemstone Faceting / Submission new Faceting Categorues
« on: October 04, 2017, 08:12:55 AM »
To Forum members who are Australian Facetors Guild members

Check out the news link on the AFG website for a submission on a new Group in the competition rules.

Views and input are sought on the submission


Regards
Flash

13
Gemstone Faceting / Submission new Faceting Categorues
« on: October 03, 2017, 06:59:18 PM »
To Forum members who are Australian Facetors Guild members

Check out the news link on the AFG website for a submission on a new Group in the competition rules.

Views and input are sought on the submission


Regards
Flash

14
Gemstone Faceting / Checker Oval
« on: September 14, 2017, 08:10:38 AM »
I am proof cutting the Checker Oval on page  43 of the Gemboree 2018 comp schedule and am having trouble with the meets on Row H.

Has anyone else tried to proof cut this design and had the same trouble?

Regards
Flash

15
Gemstone Faceting / Problems with chipping
« on: August 01, 2017, 09:24:19 PM »
One day I will Learn to be Patient.
One day I will Learn to be Patient.
One Day I WILL LEARN to BE PATIENT!!!!  :-(

Just finished my Weiland Star entry to the 2018 Queensland Faceting Comp.  It took me about 6 hours to polish all the shallow angle facets into place starting with the facets next to the crown.  I inspected the stone off the machine last night, marked the remaining 4 meet points that needed tweeking and tonight finished them.

That is when the unthinkable happened.  After removing the stone from the dop and dropping it into a bath of acetone to soak off the glue, I decided I could speed up proceedings by lifting up the stone and scraping the thick layer of glue on the pavilion a bit with my trusty knife to thin it down.

You guessed it, one slip and I have cleaved a flake from between 2 of the A Row facets on the crown.  :-( :-(

Nothing left to do now but try to hide the blemish with a well placed claw,

OR

buy a concave facetor and cut a row of concave facets starting with the fracture (rather expensive for a bit of quartz).

The last option appeals.  I can probably save the stone by turning it into an 8 point star on the edge of the faceting wheel.  The flake is right where the cut would go.  :-)

Thanks Makky for showing that it can be done. 

Any tips for a fool who is not patient enough to keep his knife away from the glue on the back of his stone. 

Happy Faceting
Not-feeling-so-Flash-now.

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