cadefoster117
having dreams about rocks
Member since December 2021
Posts: 62 
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Post by cadefoster117 on Dec 30, 2021 9:03:50 GMT -5
Good people of RTH,
I was making my first square cab and it was out of Tiger Iron. First square combined with different hardnesses of various regions of the material = big fat mistake. It didn't help that somehow one of the corners chipped and I couldn't round all the corners evenly to make up for it due to the aforementioned differing hardnesses.
Please tell me how to not do this again!
Cheers, Cade
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Post by hummingbirdstones on Dec 30, 2021 9:50:40 GMT -5
Squares are tricky. This is how I do them; it's not necessarily the correct way (if there is one). First I grind the girdle on each side of the stone. Tiger Iron is mixed hardness, as you noted, so I wouldn't start on an 80 grit wheel. I'd start on the 220 to give myself more control and to not dig in too much to the softer areas.
Once you have the shape, then start your doming. You have to remember that you need to dome the top only. I usually avoid the corners until I have the center of the cab domed. It's way too easy to over cut the corners if you're trying to do it all at the same time. I don't know if you're dopping your stones or not, but dopping them allows more control and gives you a better sight line to see what you're doing. Gently refine the corners to blend into the dome.
Always be aware of where your girdle starts at the top of the stone. If you over cut it you will need to recut the girdle on each side until you cut past the mistake to keep it even.
Repeat for the rest of the grits.
I'm looking forward to seeing how everyone else does it.  |
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cadefoster117
having dreams about rocks
Member since December 2021
Posts: 62
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Post by cadefoster117 on Dec 30, 2021 10:13:02 GMT -5
Squares are tricky. This is how I do them; it's not necessarily the correct way (if there is one). First I grind the girdle on each side of the stone. Tiger Iron is mixed hardness, as you noted, so I wouldn't start on an 80 grit wheel. I'd start on the 220 to give myself more control and to not dig in too much to the softer areas.
Once you have the shape, then start your doming. You have to remember that you need to dome the top only. I usually avoid the corners until I have the center of the cab domed. It's way too easy to over cut the corners if you're trying to do it all at the same time. I don't know if you're dopping your stones or not, but dopping them allows more control and gives you a better sight line to see what you're doing. Gently refine the corners to blend into the dome.
Always be aware of where your girdle starts at the top of the stone. If you over cut it you will need to recut the girdle on each side until you cut past the mistake to keep it even.
Repeat for the rest of the grits.
I'm looking forward to seeing how everyone else does it. Thanks for the response. Yes I had dopped the stone. It makes sense to start on a higher grit as you said. I was listening to what my teacher was telling me but he has been doing this a lot longer and probably knows how to not mess it up starting on the 80 grit.
Next time I will choose a different material until I have the technique down!
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Post by rockjunquie on Dec 30, 2021 10:15:17 GMT -5
Squares are difficult. Kudos for trying it out!!! That's a nice piece of tiger iron, too. I agree with most of what Robin said, but I do the corners a little differently. I don't think I could explain it, though. You want to watch out for "dipping" at the corners. That's when you cut down too far at a corner when making the dome. Really easy mistake to make. Try to avoid the corners after you do the girdle.
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Post by rockjunquie on Dec 30, 2021 11:59:03 GMT -5
It just occurred to me that concentrating on keeping the girdle even will really help. Whatever you have to do to keep the girdle an even height is what works.  |
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cadefoster117
having dreams about rocks
Member since December 2021
Posts: 62
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Post by cadefoster117 on Dec 30, 2021 13:55:26 GMT -5
It just occurred to me that concentrating on keeping the girdle even will really help. Whatever you have to do to keep the girdle an even height is what works. Thank you! I am excited to try again with this and all the other tips I have received in mind. |
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Post by stardiamond on Dec 30, 2021 14:44:15 GMT -5
Differing hardness requires a light touch no matter what grit a person starts on. I grind down to girdle mark on each side and then work circular until the dome is even on all four sides.
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Post by Starguy on Dec 30, 2021 14:50:14 GMT -5
cadefoster117 Do you mark your girdles. I use the aluminum pencil to mark all the way around the girdle. If you keep all of the doming above the mark, your girdle will be more regular.
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cadefoster117
having dreams about rocks
Member since December 2021
Posts: 62
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Post by cadefoster117 on Dec 30, 2021 16:45:45 GMT -5
cadefoster117 Do you mark your girdles. I use the aluminum pencil to mark all the way around the girdle. If you keep all of the doming above the mark, your girdle will be more regular. Yes I think this could have been part of the issue. Next time I will remember to mark the lines. I did on the first two, not sure why we didn't on this one. |
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Post by jasoninsd on Dec 30, 2021 17:13:11 GMT -5
cadefoster117 Do you mark your girdles. I use the aluminum pencil to mark all the way around the girdle. If you keep all of the doming above the mark, your girdle will be more regular. Yes I think this could have been part of the issue. Next time I will remember to mark the lines. I did on the first two, not sure why we didn't on this one. When I first started, I thought I didn't need the girdle line anymore...nope...wrong! LOL I think it was about my third cab that ended up looking like yours...so don't feel like you're the only one who's ever done this. For me...even now...having the girdle line is a "must"! I'm VERY conscientious about paying attention to that girdle line. If it's REALLY soft material, then I leave about a hair width of material (on the dome side) of the girdle line when I'm doing the initial grind - whether it's the 80 wheel or the 220. I know that material is going to come off at the "next" wheel I go to. Think of the girdle line as the point of "no return". Once you pass it, you're going to have to do like Robin said and remark that girdle line lower to accommodate for the point you went over. It's like drawing a line in the sand...you just don't cross it! LOL |
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Post by rmf on Dec 31, 2021 3:13:41 GMT -5
cadefoster117 There are several really good comments above, I would just add: Try your first square (or any odd shape you have not done before) on a more homogeneous material like Brazilian Agate so you can learn the steps. After you draw your line on the rock with the template take advantage of the straight line (across the face) of the 220 Diamond wheel (assuming Diamond) but cut just outside the line all the way around. Each side should be parallel with the wheel face. Do not cut the corners until you get to the 325 grit wheel. This is finer grit and takes more effort to mess up. I know from exp. I rough out by hand, Hog off material with 80 grit, staying back from the line. Dome the top to get the rough shape and get the girdle down to the 2-3 mm range. The I dop and start on the 220.
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cadefoster117
having dreams about rocks
Member since December 2021
Posts: 62
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Post by cadefoster117 on Dec 31, 2021 9:09:37 GMT -5
Yes I think this could have been part of the issue. Next time I will remember to mark the lines. I did on the first two, not sure why we didn't on this one. When I first started, I thought I didn't need the girdle line anymore...nope...wrong! LOL I think it was about my third cab that ended up looking like yours...so don't feel like you're the only one who's ever done this. For me...even now...having the girdle line is a "must"! I'm VERY conscientious about paying attention to that girdle line. If it's REALLY soft material, then I leave about a hair width of material (on the dome side) of the girdle line when I'm doing the initial grind - whether it's the 80 wheel or the 220. I know that material is going to come off at the "next" wheel I go to. Think of the girdle line as the point of "no return". Once you pass it, you're going to have to do like Robin said and remark that girdle line lower to accommodate for the point you went over. It's like drawing a line in the sand...you just don't cross it! LOL Yeah we really should have marked it. Maybe my teacher had too much faith in me haha. I really have no explanation for why we didn't and I didn't even think of it at the time. I feel silly. |
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cadefoster117
having dreams about rocks
Member since December 2021
Posts: 62
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Post by cadefoster117 on Dec 31, 2021 9:11:02 GMT -5
cadefoster117 There are several really good comments above, I would just add: Try your first square (or any odd shape you have not done before) on a more homogeneous material like Brazilian Agate so you can learn the steps. After you draw your line on the rock with the template take advantage of the straight line (across the face) of the 220 Diamond wheel (assuming Diamond) but cut just outside the line all the way around. Each side should be parallel with the wheel face. Do not cut the corners until you get to the 325 grit wheel. This is finer grit and takes more effort to mess up. I know from exp. I rough out by hand, Hog off material with 80 grit, staying back from the line. Dome the top to get the rough shape and get the girdle down to the 2-3 mm range. The I dop and start on the 220. Oh you don't even put it on the dop until 220? Interesting. I will ask about this next time. |
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Post by hummingbirdstones on Dec 31, 2021 9:39:36 GMT -5
When I first started, I thought I didn't need the girdle line anymore...nope...wrong! LOL I think it was about my third cab that ended up looking like yours...so don't feel like you're the only one who's ever done this. For me...even now...having the girdle line is a "must"! I'm VERY conscientious about paying attention to that girdle line. If it's REALLY soft material, then I leave about a hair width of material (on the dome side) of the girdle line when I'm doing the initial grind - whether it's the 80 wheel or the 220. I know that material is going to come off at the "next" wheel I go to. Think of the girdle line as the point of "no return". Once you pass it, you're going to have to do like Robin said and remark that girdle line lower to accommodate for the point you went over. It's like drawing a line in the sand...you just don't cross it! LOL Yeah we really should have marked it. Maybe my teacher had too much faith in me haha. I really have no explanation for why we didn't and I didn't even think of it at the time. I feel silly. Absolutely no reason to feel silly. You are just learning to cab and until you mess one up, you don't know that that's not the way to do it. We've all been there and messed up our fair share of cabs. Sometimes I still over cut the the dome into the girdle and have to fix it if I'm not paying as much attention as I should. It happens. |
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Post by Son Of Beach on Dec 31, 2021 9:58:16 GMT -5
What is the girdle line?
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Post by hummingbirdstones on Dec 31, 2021 10:21:49 GMT -5
The girdle is the perimeter of the cab that is cut flat for setting purposes. Some people draw a line around their stone where they want the top of the girdle to be. Not everyone does. It visually assists in keeping the girdle the same width all around the stone as you grind and also helps to prevent over-cutting of the dome.
I have a terrible eye and if I didn't draw it, my girdles would be all wonky. Vince never draws one, but he's got a good eye.
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Post by Son Of Beach on Dec 31, 2021 10:30:19 GMT -5
Thanks!
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