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 Post subject: Gemcad for beginners
PostPosted: Tue Jan 31, 2012 12:06 am 
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Gday All,
this is my first post, I have been cutting basic designs for about 2 years now and i am looking to doing some designs of my own as well as manipulating some existing designs for different material that i cut to get best results.
I have had Gemcad for 12 months but i am still struggling with inputting some designs Notibly Ovals. I have been through the base help index and instructions and cant get it to click. Might just be my thought process and something simple that i am not seeing.
Could anyone point me in the right direction if there are old posts/threads that may be of use or are there other pathways to get this info.
I Should mention that this is my 1st outing using CAD software so the knowledge on how this software works is limited.
Cheers


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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 12:27 am 
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Hi,

I think the easiest way to learn how to use GemCad is reading the manual thoroughly. You can see the manual by clicking “Help”, then “Contents” on the GemCad tool bar.

That said, here is my thought process to draw a barion oval.
1) Index. I set it with Edit on the tool bar. Here I use 96.
2) How many-fold symmetry and is it mirror symmetry (such as a heart) or radial symmetry (such as a windmill)? I input these in the symmetry boxes on the upper left corner of the GemCad screen.
3) Setting the center point. I usually start with a cone to set the center point. This is 8-fold symmetry.
Image

4) I set the stone length at 90 degrees on the index 19 (girdle), and then start chain-cutting the barion facets from the index 19. From here, it is 2-fold symmetry.
Image

5) I chain-cut all the barion facets and then start cutting the rest of the girdle.
Image

6) Then I cut splitters.
Image Image

This is J Graham’s Rainbow pattern. I suggest you to draw the entire pattern for practice.

When you create a pattern, remember that the position of a facet is always dependent on 3 things (or factors) and you need to input them. They are an index number, an angle and one reference point. The only exception is the initial cone, which requires only the index number and angle. An index and two reference points work as well. An angle and two reference points, or three reference points may work. However, index numbers may not come up as integers. That case doesn't work.

Good luck! :D

Edited later: The table also needs only two factors, i.e., the angle (0 degree) and reference point (or meet point).

_________________
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Mitch

I am a slave to cutting a stone completely free of chips and very much enjoying it.


Last edited by mhuynh on Wed Feb 01, 2012 12:33 pm, edited 1 time in total.

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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 2:02 am 
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Gday,
Thanks for the reply i will try to proof cut. I did not realise that you could change symmetry after you had started a design.
I cant work out how to attach the oval design that was posted for me in a PDF on another Forum i am trying to poof cut so i can play with the angles to get a better sparkle. It starts with the Girdle facets first.
G1 90.00 02-46-50-94
G2 90.00 06-42-54-90
G3 90.00 12-36-60-84
G4 90.00 20-28-68-76

I can get G1 facets to cut index 2 no probs and select a point for G2 all okay but from there i cant seem to work out how to get a start point :? for G3 and G4 that gives me an oval. If i could get past this initial problem i could probably handle the rest I think [-o<
Thanks again for the above info I will have a crack at it now.

Cheers


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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 2:58 am 
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Location: South Africa
Hi Drf_er,

I'm no advanced user but have the basics sorted, as Mitch points out your symetry is important, on an oval, it must be 2 fold.

Getting the L/W ratio close before going too far will save you running out of space, I do it after cutting the first step to center point, it should be visible in the bottom right corner after you do step 1.

Next hurdle if you trim too much off the view will become very small and meets on the crown will be almost impossible to make, takes a bit of fiddling until you get used to it.

What design are you trying to replicate, if somebody has it they may be able to let you know where the pitfalls are.

Have fun,

Sean.


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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 12:12 pm 
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Hi, Drft_er,

Another thing I’d like to add is you DON’T need to proof-cut a pattern as it is shown as long as the index numbers and angles are the same as the original. See I did not proof-cut the Rainbow as it is written. And I’d actually cut this pattern as I proofed.

Your girdle info of G1 to G4 provides only 2 factors I mentioned above. I get the index numbers and angle (90 degrees). I cannot draw the girdle outline without the third factor, which is the center-to-facet distance or meet points (or reference points) derived from the cone as my first post. I guess there is more info in the rest of your girdle diagram to find them out.

When you draw a pattern, it may be useful to always find out what are the three factors for the particular facet.


Hi, Sean,

When your pattern is drawn small and difficult to see the meet points, you can blowup the view. Click View then Zoom on the tool bar and choose the view you want to see. You can also scale up the figures by clicking Edit then Scale on the tool bar and clicking All and multiplying as you like.

_________________
Best regards,
Mitch

I am a slave to cutting a stone completely free of chips and very much enjoying it.


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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 5:47 pm 
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Gday Mitch,
Thanks for the reply, I guess Proof cut was the wrong term, I am trying to get a handle on how to use Gemcad more proficently. I can cut the stones from the given patterns no problems but i cant get Gemcad to cut them for me. I am really struggling to get some of the ovals i have in to gemcad.
Attachment:
oval angles.JPG
oval angles.JPG [ 15.06 KiB | Viewed 839 times ]

Attachment:
oval diagram.JPG
oval diagram.JPG [ 24.83 KiB | Viewed 839 times ]

This is the pattern i am trying to get in so i can play with the angles it was passed to me as a pdf. I want to play with the angles useing Raytrace to try and stop the leakage of light as the final cut stone is a little dull.
I cant work out how to get the girdle in as per the first 4 steps the original pattern came out of Gemcad.
Attachment:
Gem Cad 1.JPG
Gem Cad 1.JPG [ 18.4 KiB | Viewed 839 times ]


This is first step i have completed I will post again the next 3 in a new post after this one.

Hi Sean,
Thanks for the reply
Above hopfully is the pattern i am trying to input a basic 8 main Oval It cuts okay but it is a bit dull


Cheers all


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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 5:53 pm 
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Gday Again,
The next steps to where i get stuck
Attachment:
gemcad 2.JPG
gemcad 2.JPG [ 9.41 KiB | Viewed 829 times ]

Attachment:
gemcad 3.JPG
gemcad 3.JPG [ 19.42 KiB | Viewed 829 times ]

Attachment:
gemcad 4.JPG
gemcad 4.JPG [ 8.54 KiB | Viewed 829 times ]


That is as far as i can get and not sure if that is correct. I am having trouble determining the Reference points for the next girdle facet to get the correct shape. I might be totally on the wrong track. but i dont know :?

Cheers thanks again for help
Garry


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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 6:57 pm 
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Location: Pine City, NY
Strange cutting order. Try cutting the pavilion breaks first, then you'll find it much easier to cut the girdle.


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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 7:43 pm 
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When inputting a design which has already been developed, it is usually easiest to "cut" the Gemcad model together as if you were cutting it for real. With meet point designs this means starting from the most obvious meetpoint, the culet. In this case I would cut P7, P9 and P11 to the TCP. Then cut the pavilion breaks and girdle so that the girdle is level. I would cut P5/G1, then P6/G2 and so on until the pavilion is finished. Check your indexes and angles to make sure that you're matching the PDF. If you pick the P5/G1 point so that the model is too small, you can then scale the entire model to get it to just fit within the view frame. Then transfer and cut the crown starting with the break facets and you're good to go.

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Michael E.


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 Post subject: Re: Gemcad for beginners
PostPosted: Wed Feb 01, 2012 10:45 pm 
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Drft_er wrote:
Gday Mitch,
Thanks for the reply, I guess Proof cut was the wrong term, I am trying to get a handle on how to use Gemcad more proficently. I can cut the stones from the given patterns no problems but i cant get Gemcad to cut them for me. I am really struggling to get some of the ovals i have in to gemcad


LOL...All right...I proof-cut on GemCad before cutting an actual stone. So I should say "proof-cut on GemCad". But if you can proof-cut on an actual stone in a pattern, you should be able to draw that pattern on GemCad. It's all figuring out how the facets are placed.

Anyway, here’s how I draw the pavilion on GemCad.

1) Establishing the center point by picking the 4 equal main facets.
Image

2) Cutting all the main facets to the center point.
Image

3) Setting the stone length and starting the break facets from the index 20.
Image

4) Cutting the break facets and girdle facets alternately following the meet points.
Image

5) Done
Image

As I said above, this pattern is impossible to start with the girdle outline first. There is not enough information on the placement of the girdle facets. And I would cut a stone as I did on GemCad.

_________________
Best regards,
Mitch

I am a slave to cutting a stone completely free of chips and very much enjoying it.


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 Post subject: Re: Gemcad for beginners
PostPosted: Fri Feb 03, 2012 10:57 pm 
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Gday Mitch,
Thanks for the help got that in No problems. =D> The bruise on my Forehead is now healing well also. :mrgreen: :lol:
I have 4 other ovals I havnt been able to get in i might have a crack at them now.

Cheers


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 Post subject: Re: Gemcad for beginners
PostPosted: Sun Feb 05, 2012 1:35 pm 
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Hi, Drft_er,

Glad to hear you got that oval. I think if you read a pattern well and plan how you proceed cutting it, you can draw the pattern on GemCad as you would cut.

Your obstacle was not that you could not use GemCad proficently, but that you thought GemCad was something different from actual cutting. Now you are ready to draw any existing pattern and your own designs as well.

Cheers,

_________________
Best regards,
Mitch

I am a slave to cutting a stone completely free of chips and very much enjoying it.


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