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Post by holajonathan on Oct 10, 2021 0:36:52 GMT -5
A perfect dome (perfect in the geometric sense) is possible only on a round cab. I have no problem putting a decent dome on a tear drop or oval, but when I make cabs with narrow points or with lots of flat sides, I get confused about how to shape the dome. I often end up grinding the dome too low (girdle too thin) as I approach the points, and leaving it too high along flat sides. Both seem necessary in order for the dome to be properly shaped in the middle of the cab, which seems like the most important spot to have an even dome.
I am not explaining this well, but if anyone can understand my gibberish, can you please offer guidance?
I will sketch out some drawings to show what I mean if necessary.
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Post by jasoninsd on Oct 10, 2021 0:53:59 GMT -5
I think this is a great question! I really look forward to what some of the more experienced cabbers have to say about this. I have NO clue if I'm putting the correct dome on mine when I work those shapes...
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Post by rockjunquie on Oct 10, 2021 6:51:23 GMT -5
Not sure if this is what you are asking, but I work all sides to the middle and use a light touch at the points. I try to come straight out from the point so as not to have the trouble you mentioned. I never grind down to the point. As I described it, it will put your high spot of your dome in the middle. But, if you want it to be somewhere else, like the belly of a pear, you just have to adjust your grind accordingly. I think I made sense, did I?
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Post by Rockoonz on Oct 10, 2021 8:23:05 GMT -5
The nice thing about creative design is that we may call it trial and error, but in reality some of my worst "errors" in my own mind are the ones that other, less critical people really like. The real problem with some cabs is how to make a setting for them or wire wrap them when you're done. I have approached it several ways, but I think the easiest is to try to match the radii (radiuses?) on the vertical curve of the dome just like an oval. If I want to make a long narrow teardrop that comes to a sharp point or really tight rounded end, and curved perimiter all the way up, I'm going to mark what I want to end up with, then trim it out so the point is about 10% or more longer than I want, shape the dome all the way up to the point without worrying too much about the girdle height other than keeping the crown centered, then re-do the girdle to shorten the cab back to the desired height and get the girdle thickness back. I do teardrops and triangles with flat sides a lot, with those the flat sided portion of the shape is only domed on one axis, and a lot of the time the ridges created by rounding the edges remain on the finished piece, especially if it's going to be drilled as a focal bead instead of traditional cab, which I do more than cabs anyway. With the narrow ones rounding from the center out works better for me than going from the perimiter to the center and for a high dome it's easier to safe the thickness of the slab. Example: Think of this cut in half the long way.  Here's a cab from awhile back, not perfect but it started out longer as I was saying,  |
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Post by stardiamond on Oct 10, 2021 9:50:57 GMT -5
I mark a girdle line by putting the preform on a metal cab template and a pencil flat on a table. I then rotate the cab around the pencil point. I end up with about a 3mm line above the bottom.
I then start grinding off material above the line however I feel like and then work circularly above the line and toward the center. It doesn't matter if the shape is a triangle, pear or a rectangle. I use to rock but now work in a continuous circle and the high point of the cab is in the center.
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Post by holajonathan on Oct 10, 2021 12:19:49 GMT -5
Not sure if this is what you are asking, but I work all sides to the middle and use a light touch at the points. I try to come straight out from the point so as not to have the trouble you mentioned. I never grind down to the point. As I described it, it will put your high spot of your dome in the middle. But, if you want it to be somewhere else, like the belly of a pear, you just have to adjust your grind accordingly. I think I made sense, did I? Thank you. I think I am following you. The downward curve from the center of the dome to a long point has to be more gradual or the girdle at the point point will disappear. And with a more gradual slope towards the point, there will be a slight ridge from the center of the dome to the point. Does that make sense? Is that what you mean by coming "straight out from the point"? Rather than the dome having a single high point, does it have something more like a high ridge from the center towards the point, and everything else is domed in relation to the ridge? When you say you work all sides to the middle, you are not continuously spinning the cab to cut grind the dome, right? Are you first beveling the long sides of the cab (while staying away from the point), and then evening out the dome by spinning it with light pressure? With a pear shape, do you usually put the high spot in the belly? I have never considered doing that, but it seems obvious now that you mention it. I'm sorry for so many questions, but if I can really nail down how to shape the dome on different cab shapes, everything else seems easy in comparison. |
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Post by rockjunquie on Oct 10, 2021 12:44:04 GMT -5
I don't cab with a circular motion. I do the rocking thing. I cut my shape on the 80 and then cut down at an angle to my girdle line and then another angle on top of that till I'm close to the middle (highest point of the dome). Then, I rock to the center from the girdle line. For sharp corners, and this is really hard to describe, but when I have the cab cut to where the dome needs the rocking, I place the girdle line on the wheel and slowly turn the cab to round out the corner on the face of the cab. I'm not digging into it but rounding across the top of it (the corner). I never have problems cutting into the girdle line or thinning out the corner. I also don't get bevels at the corners. Wish I could show you.
As for where to put your dome- I think you are over thinking it. The dome will naturally fall in the middle if you are working towards the middle and if you want to place it elsewhere then you just work one end with longer strokes to meet at a different place on the cab (like the pear belly).
A video would be great. It's hard to explain.
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Post by holajonathan on Oct 10, 2021 12:57:19 GMT -5
The nice thing about creative design is that we may call it trial and error, but in reality some of my worst "errors" in my own mind are the ones that other, less critical people really like. The real problem with some cabs is how to make a setting for them or wire wrap them when you're done. I have approached it several ways, but I think the easiest is to try to match the radii (radiuses?) on the vertical curve of the dome just like an oval. If I want to make a long narrow teardrop that comes to a sharp point or really tight rounded end, and curved perimiter all the way up, I'm going to mark what I want to end up with, then trim it out so the point is about 10% or more longer than I want, shape the dome all the way up to the point without worrying too much about the girdle height other than keeping the crown centered, then re-do the girdle to shorten the cab back to the desired height and get the girdle thickness back. I do teardrops and triangles with flat sides a lot, with those the flat sided portion of the shape is only domed on one axis, and a lot of the time the ridges created by rounding the edges remain on the finished piece, especially if it's going to be drilled as a focal bead instead of traditional cab, which I do more than cabs anyway. With the narrow ones rounding from the center out works better for me than going from the perimiter to the center and for a high dome it's easier to safe the thickness of the slab. Example: Think of this cut in half the long way. Here's a cab from awhile back, not perfect but it started out longer as I was saying, Thank you for the clear and thorough explanation. I have been trying to completely remove the ridges on triangles, which isn't really possible without grinding the girdle too low at the points. I will try leaving the ridges much more pronounced and see how I like the final look. Sometimes I confuse a symmetrical dome (always necessary on a symmetrical cab) with an even dome -- in the sense of an even curve from a center point to every point on the edge (not really possibly with many shapes). |
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Post by holajonathan on Oct 10, 2021 20:14:39 GMT -5
I don't cab with a circular motion. I do the rocking thing. I cut my shape on the 80 and then cut down at an angle to my girdle line and then another angle on top of that till I'm close to the middle (highest point of the dome). Then, I rock to the center from the girdle line. For sharp corners, and this is really hard to describe, but when I have the cab cut to where the dome needs the rocking, I place the girdle line on the wheel and slowly turn the cab to round out the corner on the face of the cab. I'm not digging into it but rounding across the top of it (the corner). I never have problems cutting into the girdle line or thinning out the corner. I also don't get bevels at the corners. Wish I could show you.
As for where to put your dome- I think you are over thinking it. The dome will naturally fall in the middle if you are working towards the middle and if you want to place it elsewhere then you just work one end with longer strokes to meet at a different place on the cab (like the pear belly).
A video would be great. It's hard to explain.
This is very helpful. Thank you. If I understand correctly, your technique (progressively beveling each side and smoothing out the bevel lines) sort of automatically creates a dome that reflects, or in a sense mirrors, the shape of the cab. You don't have to plan out the dome, because it is the natural consequence of the beveling and smoothing. Your technique changes slightly with points, where you round off the bevel lines that meet at the point (across the top, as you say), but you do not actually bevel from the point towards the center of the cab. This last point directly answers my original question. When I tried to bevel from the point to the center, the point always got too low. Do you currently have photos of your cabs on any website? I will see what I can find in RTH threads, but I would love to see some photos of your cabs with long points, flat sides, or geometric shapes. A profile shot or a photo at something like a 45 degree angle would be especially helpful, since a well-shaped dome tends to disappear when viewed from the font. Finally, it would be awesome to see a video of you making a cab. In particular, a close up of your hands and the wheels, without or without you explaining what you are doing. If you ever want to try, I would be happy to send you something like this, which would make it easy to position a cell phone camera to capture the action. By using such a stand with the front facing cell camera, the screen serves as a video monitor as well. Thanks again. |
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Post by rockjunquie on Oct 10, 2021 20:44:02 GMT -5
holajonathan I don't have a cell phone. Yeah, I know I'm the last person on the planet... but I don't need one, so I don't have one.
I think you got it. The point where I work around the point is hard to describe, but I think you got the gist.
I prefer to work angular pointy cabs. When I first started that was all I did- just about. I don't sell anything anywhere anymore, but I have a lot of pictures. I'll find some in the morning for you. I use a dop, too. I don't know if that makes any difference.
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Post by stephan on Oct 10, 2021 21:11:19 GMT -5
I don't have a cell phone.  |
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tumblee
starting to spend too much on rocks
Member since March 2021
Posts: 154
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Post by tumblee on Oct 10, 2021 21:16:10 GMT -5
I don't have a cell phone.  |
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Post by rockpickerforever on Oct 10, 2021 21:38:33 GMT -5
holajonathan I don't have a cell phone. Yeah, I know I'm the last person on the planet... but I don't need one, so I don't have one.
I think you got it. The point where I work around the point is hard to describe, but I think you got the gist.
I prefer to work angular pointy cabs. When I first started that was all I did- just about. I don't sell anything anywhere anymore, but I have a lot of pictures. I'll find some in the morning for you. I use a dop, too. I don't know if that makes any difference.
Addressing the cell phone issue - We didn't get ours until after Bob's parent's died, and we needed a way to keep in touch with his younger sister, who was still living in the parent's home with her older sister. She could lock herself in her bedroom, but we felt she was in danger from the older sister, who would sever the phone cord going to her room, she had no way to communicate with anybody, call the cops, nothing. After the home was sold, and the estate settled, she (the good sister) lived with us for several years. Met up (through the internet, of course) with an old classmate. Has been living with him since moving out of here. Lives a half hour north of us, still close by. The other sister is OCD, psycho, no income, and not very nice. She's been in shelters on and off, don't really know (or care!) what she is doing now. The two sisters do stay in contact via FB. Good for them. Tela, just so you know you are not the last person in the world without a cell phone - my brother, who turned 62 last March, has never had, nor ever will have, a cell phone. He has no need. Plus, he would have to pay for it. Separating him from his money is like pulling teeth, lol. ETA - sorry to stray so far off topic, but you were mentioning not having a cell phone, right? Haven't done any cabbing for some while now. It depresses me to see what people consider well made cabs. (Why I rarely comment on - or enter - the cabbing contest. Sorry, that's just how I see it.) Some of you are really getting better at it, though. Y'all have fun! That's what it is all about. I can always delete this post if it triggers anyone...... |
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Post by rockjunquie on Oct 10, 2021 21:53:09 GMT -5
holajonathan I don't have a cell phone. Yeah, I know I'm the last person on the planet... but I don't need one, so I don't have one.
I think you got it. The point where I work around the point is hard to describe, but I think you got the gist.
I prefer to work angular pointy cabs. When I first started that was all I did- just about. I don't sell anything anywhere anymore, but I have a lot of pictures. I'll find some in the morning for you. I use a dop, too. I don't know if that makes any difference.
Addressing the cell phone issue - We didn't get ours until after Bob's parent's died, and we needed a way to keep in touch with his younger sister, who was still living in the parent's home with her older sister. She could lock herself in her bedroom, but we felt she was in danger from the older sister, who would sever the phone cord going to her room, she had no way to communicate with anybody, call the cops, nothing. After the home was sold, and the estate settled, she (the good sister) lived with us for several years. Met up (through the internet, of course) with an old classmate. Has been living with him since moving out of here. Lives a half hour north of us, still close by. The other sister is OCD, psycho, no income, and not very nice. She's been in shelters on and off, don't really know (or care!) what she is doing now. The two sisters do stay in contact via FB. Good for them. Tela, just so you know you are not the last person in the world without a cell phone - my brother, who turned 62 last March, has never had, nor ever will have, a cell phone. He has no need. Plus, he would have to pay for it. Separating him from his money is like pulling teeth, lol.
Yeah, I figure when I really need one, I'll get one. But, I really don't miss having one at all. I'm not a Luddite and I can afford a phone- just don't have a use for one. My kids got me one a while back and I gave it away. I did have an old one around 2000 when I was working and had teenagers at home, but when they were stupid phones.
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Post by rockjunquie on Oct 10, 2021 21:57:46 GMT -5
holajonathan I found some pics to help. I'll start a new thread and tag you when I get it up.
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Post by rockpickerforever on Oct 10, 2021 22:00:03 GMT -5
That's what I have, a stupid phone, an old flip phone! This is the first and only cell phone I have purchased. Although my sister gave me an old phone of hers that I use as a camera, and for the internet, using the wifi at home.
It doesn't have a sim card, so can't/don't use it as a phone.
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Post by stephan on Oct 10, 2021 22:31:32 GMT -5
I don't cab with a circular motion. I do the rocking thing. I cut my shape on the 80 and then cut down at an angle to my girdle line and then another angle on top of that till I'm close to the middle (highest point of the dome). Then, I rock to the center from the girdle line. For sharp corners, and this is really hard to describe, but when I have the cab cut to where the dome needs the rocking, I place the girdle line on the wheel and slowly turn the cab to round out the corner on the face of the cab. I'm not digging into it but rounding across the top of it (the corner). I never have problems cutting into the girdle line or thinning out the corner. I also don't get bevels at the corners. Wish I could show you.
As for where to put your dome- I think you are over thinking it. The dome will naturally fall in the middle if you are working towards the middle and if you want to place it elsewhere then you just work one end with longer strokes to meet at a different place on the cab (like the pear belly).
A video would be great. It's hard to explain.
This is very helpful. Thank you. If I understand correctly, your technique (progressively beveling each side and smoothing out the bevel lines) sort of automatically creates a dome that reflects, or in a sense mirrors, the shape of the cab. You don't have to plan out the dome, because it is the natural consequence of the beveling and smoothing. Your technique changes slightly with points, where you round off the bevel lines that meet at the point (across the top, as you say), but you do not actually bevel from the point towards the center of the cab. This last point directly answers my original question. When I tried to bevel from the point to the center, the point always got too low. Do you currently have photos of your cabs on any website? I will see what I can find in RTH threads, but I would love to see some photos of your cabs with long points, flat sides, or geometric shapes. A profile shot or a photo at something like a 45 degree angle would be especially helpful, since a well-shaped dome tends to disappear when viewed from the font. Finally, it would be awesome to see a video of you making a cab. In particular, a close up of your hands and the wheels, without or without you explaining what you are doing. If you ever want to try, I would be happy to send you something like this, which would make it easy to position a cell phone camera to capture the action. By using such a stand with the front facing cell camera, the screen serves as a video monitor as well. Thanks again. I think you get the idea. For oddly shaped cabs, I’ll spend some time finding the approximate geometric center of the cab and working toward that as the top of the dome. Rarely (depending on the shapes of the dome and the starting material), I’ll take an almost faceted approach to achieving the general shape, and then round the edges. This is more common if cabbing small rough. |
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Post by holajonathan on Oct 10, 2021 23:23:20 GMT -5
holajonathan I don't have a cell phone. Yeah, I know I'm the last person on the planet... but I don't need one, so I don't have one.
I think you got it. The point where I work around the point is hard to describe, but I think you got the gist.
I prefer to work angular pointy cabs. When I first started that was all I did- just about. I don't sell anything anywhere anymore, but I have a lot of pictures. I'll find some in the morning for you. I use a dop, too. I don't know if that makes any difference.
Addressing the cell phone issue - We didn't get ours until after Bob's parent's died, and we needed a way to keep in touch with his younger sister, who was still living in the parent's home with her older sister. She could lock herself in her bedroom, but we felt she was in danger from the older sister, who would sever the phone cord going to her room, she had no way to communicate with anybody, call the cops, nothing. After the home was sold, and the estate settled, she (the good sister) lived with us for several years. Met up (through the internet, of course) with an old classmate. Has been living with him since moving out of here. Lives a half hour north of us, still close by. The other sister is OCD, psycho, no income, and not very nice. She's been in shelters on and off, don't really know (or care!) what she is doing now. The two sisters do stay in contact via FB. Good for them. Tela, just so you know you are not the last person in the world without a cell phone - my brother, who turned 62 last March, has never had, nor ever will have, a cell phone. He has no need. Plus, he would have to pay for it. Separating him from his money is like pulling teeth, lol. ETA - sorry to stray so far off topic, but you were mentioning not having a cell phone, right? Haven't done any cabbing for some while now. It depresses me to see what people consider well made cabs. (Why I rarely comment on - or enter - the cabbing contest. Sorry, that's just how I see it.) Some of you are really getting better at it, though. Y'all have fun! That's what it is all about. I can always delete this post if it triggers anyone...... I don't get the sense you were referring to me, but if my cabs depress you, that's why I'm here asking questions.  Because I want to improve, and I'm willing to put in the time and effort to do so. I've never been very good at anything when I first started doing it, but with practice, perseverance, and asking questions, I've mastered things at least as difficult as make good cabs. So there is hope for some of us. |
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Post by holajonathan on Oct 10, 2021 23:25:43 GMT -5
Addressing the cell phone issue - We didn't get ours until after Bob's parent's died, and we needed a way to keep in touch with his younger sister, who was still living in the parent's home with her older sister. She could lock herself in her bedroom, but we felt she was in danger from the older sister, who would sever the phone cord going to her room, she had no way to communicate with anybody, call the cops, nothing. After the home was sold, and the estate settled, she (the good sister) lived with us for several years. Met up (through the internet, of course) with an old classmate. Has been living with him since moving out of here. Lives a half hour north of us, still close by. The other sister is OCD, psycho, no income, and not very nice. She's been in shelters on and off, don't really know (or care!) what she is doing now. The two sisters do stay in contact via FB. Good for them. Tela, just so you know you are not the last person in the world without a cell phone - my brother, who turned 62 last March, has never had, nor ever will have, a cell phone. He has no need. Plus, he would have to pay for it. Separating him from his money is like pulling teeth, lol.
Yeah, I figure when I really need one, I'll get one. But, I really don't miss having one at all. I'm not a Luddite and I can afford a phone- just don't have a use for one. My kids got me one a while back and I gave it away. I did have an old one around 2000 when I was working and had teenagers at home, but when they were stupid phones.
I hardly ever use my phone as a phone. But I use it constantly as a photo camera, video camera, mobile internet device, flashlight... the list goes on and on. I suppose some people use a tablet for those purposes. On occasion, when traveling, I find the actual phone function to be useful. But beyond that, I suppose I could live happily with a pocket size tablet that doesn't make phone calls. |
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Post by rockpickerforever on Oct 11, 2021 0:13:43 GMT -5
Haven't done any cabbing for some while now. It depresses me to see what people consider well made cabs. (Why I rarely comment on - or enter - the cabbing contest. Sorry, that's just how I see it.) Some of you are really getting better at it, though. Y'all have fun! That's what it is all about. I don't get the sense you were referring to me, but if my cabs depress you, that's why I'm here asking questions. Because I want to improve, and I'm willing to put in the time and effort to do so. I've never been very good at anything when I first started doing it, but with practice, perseverance, and asking questions, I've mastered things at least as difficult as make good cabs. So there is hope for some of us. No, Jonathan, definitely NOT referring to you. That really wasn't fair to throw that out like that, it actually refers to a discussion long before you became a member. And no, it's not any cabs that depress me, it was certain people's attitudes about what makes a perfect cab. Flat back, girdle, domed top. That's the basics. There are actually criteria called out. I searched different club's websites online, looking for guidance to make the perfect cab. Some clubs held regular cab making contests, they were judged (point system) and critiqued. People learned by the process. When I presented this info here on RTH, I was surprised by the amount of negative feedback I received! Some just wanted to keep on doing them the way they always did. Until people can agree on what makes a perfect cab, and everyone is playing by the same rules, it is kind of pointless to pick a winner when everyone's ideas are different! Apples and oranges. Competition is okay, if you are aiming for the same completed product. Now, if anyone just wants to make them for fun, that's fine. As mentioned previously, MANY of the newer members are getting better and better at cabbing, just as the tumblers are also getting better with their tumbling, producing nicer and shinier rocks. Keep it up, holajonathan . Improving one's work, and having fun are the two most important things |
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Because I want to improve, and I'm willing to put in the time and effort to do so. I've never been very good at anything when I first started doing it, but with practice, perseverance, and asking questions, I've mastered things at least as difficult as make good cabs. So there is hope for some of us. 
