Post subject: How do you find the center of rough to attach the dop?
Posted: Thu Feb 06, 2014 9:44 pm
Established Member
Joined: Sat Dec 01, 2012 5:27 pm Posts: 41
I have been having a hard time finding the center of uneven rough. I cut a flat then use the best guess method now. But I am hoping you folks will have a better guess method than me.
As a centering aid I normally use this device, recently emerged from the research and development arm of Luddite Laboratories and now placed before the public for the first time.
Attachment:
lud-dev-1-7666.jpg [ 213.77 KiB | Viewed 2570 times ]
Here it is in vertical configuration.
Attachment:
lud-dev-2-7667.jpg [ 137.92 KiB | Viewed 2570 times ]
Post subject: Re: How do you find the center of rough to attach the dop?
Posted: Thu Feb 06, 2014 11:30 pm
Moderator
Joined: Fri Jun 25, 2010 10:06 pm Posts: 2267 Location: Chapel Hill, NC / Toronto, ON
I usually cut a flat, then print out the crown view of the design with a black circle on the exact center. I line that up over the flat that I've just cut, and take a Sharpie and bleed it through the black circle, so I get a perfect point on the exact center. Then, I use either a Guiu, a MagDop with soft putty, or a Themis to perfectly line up the rough.
Post subject: Re: How do you find the center of rough to attach the dop?
Posted: Fri Feb 07, 2014 1:42 am
Valued Contributor
Joined: Thu Oct 04, 2012 1:57 am Posts: 138 Location: Germany
Hans Durstling wrote:
As a centering aid I normally use this device, recently emerged from the research and development arm of Luddite Laboratories and now placed before the public for the first time.
Post subject: Re: How do you find the center of rough to attach the dop?
Posted: Fri Feb 07, 2014 2:42 am
Valued Contributor
Joined: Thu May 15, 2008 4:55 am Posts: 237 Location: Vienna, Austria
What I think most about is on where placing the (temporary) table plane! Dopping then is most times a free hand thing, with small rough or on days with bad aim ( not always because of what you might think ) i use the putty used for mounting mineral specimen in a big cone dop and my transfer fixture to center the rough. Also, like lorne, I would like to know: What is a Themis?
_________________ To see a world in a grain of sand,
And a heaven in a wild flower,
Hold infinity in the palm of your hand,
And eternity in an hour.
Post subject: Re: How do you find the center of rough to attach the dop?
Posted: Fri Feb 07, 2014 12:13 pm
Established Member
Joined: Thu Jan 10, 2013 6:36 pm Posts: 19
DTVM, Drug stores sell a ear plug material that is made of silicone that is moldable ,sticky , and heat resistant . Five plugs come in the packet , they won't dry out and remove easily from the rough or the tool . Howard J. Shamy
Post subject: Re: How do you find the center of rough to attach the dop?
Posted: Fri Feb 07, 2014 2:51 pm
Gemology Online Veteran
Joined: Sat Apr 24, 2010 7:10 am Posts: 584
I use black wax and eye ball it...then cut the first level of the pavilion facets too shallow to come to a point..or what ever that stone will have and look at it. If it isn't centered simply reheat the stone,dop and wax evenly and make the adjustment.But be careful not to force the stone and weaken the bond...heat evenly and slowly til you just begin to feel it give a bit...but then I cut curved stair rails into two different flat areas at the top and bottom of a stair case and get a perfectly mated surface with a tool meant to cut flat square wood so if you don't have the eye ball skills the other tools can help.
This is the first Themis, magnetic dop with a conical projected laser. Then came:
Themis B, what Arya has. This has the magnetic dop, laser with crosshair projection, adjustable optic mounts for the dops and a USB camera/microscope when used with your computer and the crosshair program, you can align girdles, center and adjust infinitely. Then came:
I got carried away, but 3 are gone and I have one left.
Post subject: Re: How do you find the center of rough to attach the dop?
Posted: Fri Feb 07, 2014 4:48 pm
Gemology Online Veteran
Joined: Sat Apr 24, 2010 7:10 am Posts: 584
Morpheus wrote:
What Arya is talking about is:
This is the first Themis, magnetic dop with a conical projected laser. Then came:
Themis B, what Arya has. This has the magnetic dop, laser with crosshair projection, adjustable optic mounts for the dops and a USB camera/microscope when used with your computer and the crosshair program, you can align girdles, center and adjust infinitely. Then came:
I got carried away, but 3 are gone and I have one left.
Post subject: Re: How do you find the center of rough to attach the dop?
Posted: Fri Feb 07, 2014 6:23 pm
Established Member
Joined: Thu Feb 09, 2012 7:30 pm Posts: 40
I'm probably old school here as I tend to use a particular shellac to dop most rough (actually a wax with high shellac content that at least used to be sold as dopping shellac a decade ago). I dop it by eyeball, then start roughing in an oversized girdle, essentially just cleaning up the edges to define the part of the rough I'm going to use.
Then I use the facet machine and the lap to measure the desired center of the girdle. Place the stone on the lap so it just contacts at the lowest point. Rotate 180 degrees and change mast height to find where that just contacts. Set mast height in the middle. Hit dop stick with a little heat and gently push the dop stick down as the stone is supported by the lap. Now it is centered in that direction. The method is capable of rather good accuracy.
Post subject: Re: How do you find the center of rough to attach the dop?
Posted: Fri Feb 07, 2014 7:46 pm
Moderator
Joined: Fri Jun 25, 2010 10:06 pm Posts: 2267 Location: Chapel Hill, NC / Toronto, ON
G_T wrote:
I'm probably old school here as I tend to use a particular shellac to dop most rough (actually a wax with high shellac content that at least used to be sold as dopping shellac a decade ago). I dop it by eyeball, then start roughing in an oversized girdle, essentially just cleaning up the edges to define the part of the rough I'm going to use.
Then I use the facet machine and the lap to measure the desired center of the girdle. Place the stone on the lap so it just contacts at the lowest point. Rotate 180 degrees and change mast height to find where that just contacts. Set mast height in the middle. Hit dop stick with a little heat and gently push the dop stick down as the stone is supported by the lap. Now it is centered in that direction. The method is capable of rather good accuracy.
Gerald
Interesting way to dop. I can imagine that for very large or incredibly expensive pieces of rough, this would be a good way to maximize yield. It does seem very time-consuming though, and I'm an impatient man, so I'll stick with getting it nearly perfect the first time and throwing my hands up afterwards
Users browsing this forum: No registered users and 30 guests
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum