Forums Beginner Questions Table cutting

21 replies, 9 voices Last updated by tucsonbear 6 years, 9 months ago
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    • #2643

      scottwkelley
      Participant
      @scottwkelley

      I am having an issue with the table cut leaning it seems to one side as though it is a little heavy to the center of the lap. I believe everything appears to be okay. I am using a facetron machine. Any suggestions on trouble shooting or is it technique.

    • #2645

      carlshearer
      Participant
      @carlshearer

      well, i am not an expert, but everystone i cut has the table leaning to one side. you need to use the cheater to level it out and try and “make your meets”. of course , if it is way out then you have made some mistakes earlier in your cutting of the stone.

    • #2646

      scottwkelley
      Participant
      @scottwkelley

      Thanks Carl,
      Yea it is really close where the meets are not going to happen at the same time. But it is close. I have yet to experiment with the cheat. Any suggestions as what to expect by going one way or the other and how much does it move.

    • #2647

      Alan Balmer
      Keymaster
      @alanbalmer

      I don’t have a Facetron, so I can’t tell you off hand. But my answer is Experiment and Observe. For side to side tilt, coat the table with magic marker, then swipe it across the lap. Look at where the ink is rubbed off. Now change the cheater a bit and do it again. You’ll soon get comfortable with what direction and how much.

      For front to back tilt, do the same thing, but adjust the height of the head on he mast.

    • #2648

      scottwkelley
      Participant
      @scottwkelley

      Very good Alan, thanks a bunch. My facetron has been darn near perfect but as I have been using it this has changed a little and I am glad I asked before thinking to try other things or giving up. It has been the front to back. I will do the ink test to figure it out.

    • #2662

      carlshearer
      Participant
      @carlshearer

      yes, for me it has been trial and error and getting a feel for it eventually. but i suggest starting small, very little correction and see what happens. if you try to make to big a change at once you might be sorry.
      the problem of the facets not all lining up, even when you adjust with the cheater is a common one for me – in fact it is most of the time. this stems, i believe from not being as exact as we could be in our earlier meets – assuming you start with cutting the pavillion then any errors are greatly magnified by the time you get to the table.

    • #2663

      scottwkelley
      Participant
      @scottwkelley

      Thanks Carl, I agree. I am very new and with every stone so far has been a learning experience and understanding the machine and what it can do is a challenge. Performing the cut to the drawing and polishing is fun and frustrating as each stone teaches me more about precision and quality. Everything hinges off the first cut and the placement of the dop. I am excited to send in the novice stone for evaluation. What is sad is I know more now since I cut it and feel I can do better already. Time is limited.

    • #2669

      Tom Mitchell
      Keymaster
      @tommitchell

      Great discussion gentlemen. Every faceter needs to learn how to use the cheater to rotate the stone left to right and how to cheat top to bottom. Word of caution though. The cheater should only be used very sparingly. It should not be relied on to polish every facet.

      A post script to the discussion: when you are finally finished and have removed your stone from the quill, don’t forget to reset the cheater back to “0”. Facetron has very little play, left to right with it’s rotational cheater. If you forget to reset it back to “0” before beginning a new stone you may be out of luck if you need to use it on the next stone.

      Tom Mitchell
      Mitchell Jewelry Studio
      352-751-0906

    • #2670

      Gregory Hays
      Participant
      @gregoryhays

      My machine is a late 90’s MDR PRO 300C. So the cheater is a invaluable tool and I had to lean to use it early on. I agree with Tom that you have to remember to reset to absolute zero before starting your next stone. Someday I may be allowed to trade in my dinosaur for one of the latest and greatest. But for now I will keep cheating away.
      Greg
      The Gem Garden
      San Marcos CA

    • #2671

      Alan Balmer
      Keymaster
      @alanbalmer

      Greg, a new machine won’t spare you the cheating game 🙂 There will always be accumulated errors.

      There’s a nice illustration of the table adjustment process on page 192 of Tom Herbst’s book, “Amateur Gemstone Faceting, Volume 1: The Essentials. At a bit under $27, this book is the best faceting investment you’ll ever make.

    • #2672

      scottwkelley
      Participant
      @scottwkelley

      At the time I am cutting a large piece with large facets, wide and long. I am taking the opportunity using large facets to learn this cheat method and to understand great polishing. I marked my formed facet with black perminant marker and colored it in. What I found was very enlightening. I then and will start using this method a little more often to let me know which way to go as I don’t have enough experience to tell by eye. My machine doesn’t require a lot of adjustment but my laps appear to have have the front to back adjustment depending where I polish on the lap. The longer the facet the front to back on the 96 and as close to the hard stop seems to make huge differences in the polish. Now how to detect minor scratches before the 1200 lap.

    • #2673

      carlshearer
      Participant
      @carlshearer

      the other thing that i have found with my facetron is that the “zero” on the cheater is not the actual zero, it is off a little. i dont know how or why but it is . discovering that saved me alot of work.

    • #2675

      Tom Maxwell
      Participant
      @tmax

      Hi Carl,

      Check out John Baily’s U-Tube video – https://www.youtube.com/watch?v=EvinThs_LQw
      This should help a lot!

      Tom Maxwell

    • #2676

      carlshearer
      Participant
      @carlshearer

      Thanks Tom, i have seen that video already. i agree it is excellent!

    • #2705

      michaelnoetzel
      Participant
      @michaelnoetzel

      Scott, I have a Facetron. The use of a cheater adjustment is invaluable for you to level your table and get it to meet adjacent facets. First off you need to have the machine itself zeroed out before you ever begin. Install the 45° adapter that you would use to cut and polish the table and lay it down on a clean polishing lap or master lap with the machine set at 45° and a 96/0 index (zero I dex on whatever gear you are using). You will have to raise or lower the quill with the fine adjustment so that the adapter is JUST sitting on the lap (I have a ceramic lap I like to use, because it is solid and absolutely flat). The cheater should be set at EXACTLY zero. I even make a tiny mark on the silver dial right next to the tick mark on the anodized area to the right so you can see them line up just that much better. Also, make note that the grooved piece of metal that points to the index mark (say the 96 mark on a 96 gear) is centered in the channel is rests in. There should be an equal amount of space on each side; about 1/8″ or so.

      If you can slip a piece of paper (find some sheet of fine grained paper like a glossy magazine or smooth office paper to use as a shim stock or an actual piece of shim if you have one), your cheater is not zeroed. Don’t move the cheater, make the adjustment with the star nut that holds the index gear in place. You need an Allen wrench for this. Loosten the nut and the adapter will twist left and right. What satisfied, tighted the nut. Take a really long time making sure this is as accurate as you can do it.

      When you next go to cut a new stone, if your machine is zeroed perfectly, when you start cutting your girdle, you shouldn’t have to adjust your girdle at all for all facets to line up as you go round (meaning to use the cheater). Depending on your level of skill and equipment (power eye loupe, head visor or microscope), as you do this each facet will be microscopically a little higher or lower than it should be but do your very best to line up each corner one at a time.

      The art of gemstone cutting reflects the skill of the faceter to line up not only the girdle facets but all others until you finally get to the table. It is pretty much impossible to get to the point of cutting and polishing the table and not have to use the cheater because of the microscopic faults in lining up all your previous facets. It’s just a part of the process that you need to master but if your machine was properly zeroed from the beginning and you’ve been attentive to lining every facet up pretty well, the amount of cheating should be kept to a minimum. You should not be able to visually see that a table (that is supposed to be level by design) is tilted: ever. But our vision typically is not good enough to see minor cheats.

      The cheater on the Facetron machines are marked 0-7. With your stone in the adapter, pivot the quill uptight to inspect the table. As you pointed out marking the stone with Sharpie markers before you cut or polish will let you see where the grinding of the stone is actually taking place. If you find that you have to tilt the stone so that it cuts/polishes a little more on the left, adjust the silver cheater -‘downward’ so that you are going from the zero mark down to seven or so. Maybe more or less, you have to figure out how much.

      If you need to cut more to the right, you ‘go up’, meaning your adjustment would go from zero to one. If you need to shave more off the top or bottom of the stone that is the height adjustment and not the cheater. Mastering the cheater takes some time but is critical to improving your abilities.

    • #2707

      scottwkelley
      Participant
      @scottwkelley

      Thank you so much. So far my machine has been accurate as far as I can tell. The left to right is good. After using the marker I found sweeping the lap brought in the top and bottom evenly and also helped me with a better polish. I hope I never find myself having to use the cheat but I understand better now that it will be for the left to right mis aligned. Taking the time to make sure everything is true before the first cut is as important as the CP being perfect.
      My facets are improving and my meets are coming in true and with better precision. Loving it.

    • #2725

      scottwkelley
      Participant
      @scottwkelley

      Hello all,
      Well the table cutting is improving and I have another question and this stone is teaching me something.
      The cut is Kristine Apex a antique square cushion. When I got to the table I laughed and did not believe what it said. 5 degree’s. What? The reason I laughed is because of all the angle setting to the 100th. I rounded off and called it good. Like making it 47 degrees.
      Well this is what I experienced when cutting this table. I found that I had to almost round the table by cheating the front to back to meet the points while not moving the right to left at all. I believe the 5 degree is meaning to center the middle of the table to allow the 5 degree to the front and negative 5 degree to the rear/back. When I did this the meets came in with little to no frustrations.
      Is this a good example of cheating but purposely having to be done?

    • #2728

      Alan Balmer
      Keymaster
      @alanbalmer

      There’s a reason this was a Master’s stone 🙂

      Sounds like you did good. As long as you make the meets, there’s no shame in using the cheater or making minor adjustments to the angle, which is what you’re calling cheating front to back.

      This is what’s called an “apex crown”, by the way. It’s not really a table. Angles that low can be very tricky to cut.

      Some years ago Glenn Klein waged a campaign to eliminate the words “cheater” and “cheating”. You might find this interesting:
      Get Rid of Cheater

    • #3277

      gemmakermz
      Participant
      @gemmakermz

      i see many answers all very good, yes you have to use those cheaters, everyone does i have found when cutting and polishing a lot of people do so swinging the stone from center to side. if you make sure your head and mast is aimed straight to the center of the cutting wheel and finish you cuts straight at the center of the lap you rill have less to cheat. a lot of the laps are a bit higher in center than on the edge even though their machine to not be, this causes an anglure cut on my ultra tec is rare that i have to cheat the table. mike zinski

    • #3405

      scottwkelley
      Participant
      @scottwkelley

      Thank you for the help. I figured it out and feel silly. But after going back and reading Jim Perkins manual he talks at the end of fixing stuff. What I was not doing was taking the table down far enough to meet the last facet running through the top crown facet, then going back and bringing in the meets. After doing that things are getting a whole lot better and the crowns are looking magnificent to me now. As a student I find these problem solving issues to be a draw for me to figure out and master.

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    • #3421

      tucsonbear
      Participant
      @Tucsonbear

      You guys are making me feel ancient. I bought a Graves Mark IV back in 1980, and I’m still using it. It’s modified into a nice bench top with a washing machine motor. For years now, I’ve been wanting to get the 1/10° angle mod, but as it means sending my head back to Graves for probably a couple weeks, I manage to keep putting it off. The cheater is pretty straightforward, and I can eyeball the angles close enough. Learn to “cut a little, and look a lot”, and you can head problems off before they become headaches. I’m deaf now, so I don’t bother listening, but learn to get the feel of the quill when cutting. Learn to use your height adjustment to make your meets, and you don’t need a dial indicator. Use your eyes, and learn your adjustments!
      Most problems with tables are caused by under or over cutting the girdle or star facets, use your eyes to make these as perfect as possible before you get to the table.

    • #3422

      tucsonbear
      Participant
      @Tucsonbear

      P.S. back in the day, they used to cut fairly decent stones with a jamb peg. Cheating was easier then!

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