BC carving board

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tsenglo
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BC carving board

Messaggio da tsenglo » martedì 12 luglio 2005, 7:52

Claudio,
I got the BC carving board a couple months ago, a very useful tool, and the ball clamp quite stable with no problem so far. However, I am about to start to dig out the back, found out it could not fit well on the board. The question is do you revised the board and make it deeper to accomodate the arch of the back?

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Messaggio da claudio » martedì 12 luglio 2005, 12:02

Rarely my maple backs and spruce tops go over respectively 15mm and 16mm, so the carving board fits well and I didn't revise it.
What's the height of your back?

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Messaggio da tsenglo » martedì 12 luglio 2005, 15:39

claudio ha scritto:What's the height of your back?
I have a 16.3mm, I thought I will have to lower it in this case, not the carving board

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Messaggio da claudio » martedì 12 luglio 2005, 16:18

it's much better to lower your back at about 14,5\15mm. But the height is depending from the model are you using. If you are using a strad model, then the 14,5mm is good for you. Generally speaking, the back have to be lower than the top, because the back works like a compressed spring. Sometimes we see the opposite situation on some old violins, but these have to be considered like exceptions. In any case if you want use a back higher than the top, you have to know what are you doing.

tsenglo
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Weak glue or bad joint?

Messaggio da tsenglo » lunedì 18 luglio 2005, 21:10

The plate separated while I was working on hollowing. What is your opinion? Is the plate rescuable? and what kind of tool I will need?
thanks in advance for the advice.
Immagine

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Messaggio da claudio » lunedì 18 luglio 2005, 23:28

tsenglo, this accident has 2 faces:
first, this splitted back is very difficult to repair.
second, fortunately it splitted now and not on the finished instrument.

You need of 2 special clamps with screws, I don't remember its name, but you can find it easily on this forum and on the net. Then you have to try your better way to reglue the back.
It seems that your glue was not so strong, what kind of glue are you using. If it is hide glue, be sure to use it at right proportions and temperature: 1part of hide glue and 2 or 2 parts of water warmed up at 70°C, ambient temperature 20°C.
Let me know if you resolve or not this problem.

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good news and bad news

Messaggio da tsenglo » lunedì 18 luglio 2005, 23:39

I thought this will not be a repair difficulty because it should be a common problems for the old instruments which the plate will be split after certain years. Now I know I might be in deep troubleby the words from you a professional maker.
do you think the tool in the picture will do the job?
Immagine

how many set do I need if it is the tool?

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Messaggio da claudio » martedì 19 luglio 2005, 2:53

you need 5 of those clamps in the photo and 2 other special clamps to hold the wood in the right position. Yes, this is a common problem for the old violins, but it's very difficult that they split in the middle, so the normal cracks are not so difficult to repair. Be careful to the hide glue.

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pciture of the special clamp

Messaggio da tsenglo » martedì 19 luglio 2005, 4:51

Could you show the picture of special clamp I will need?

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Messaggio da claudio » martedì 19 luglio 2005, 10:54

Immagine

tsenglo
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clamp

Messaggio da tsenglo » martedì 19 luglio 2005, 16:49

thank you, I have one of them, a cheaper version, not working very well. I could actually use rubber band on button part. I will let you know if I have any difficulty to fix it. Yes, I thought 1 to 4 glue was OK, it turned out to weak, will get back to 1 to 2 when I regule the back.

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Re: good news and bad news

Messaggio da tsenglo » venerdì 19 agosto 2005, 16:41

tsenglo ha scritto:I thought this will not be a repair difficulty because it should be a common problems for the old instruments which the plate will be split after certain years. Now I know I might be in deep troubleby the words from you a professional maker.
do you think the tool in the picture will do the job?
Immagine

how many set do I need if it is the tool?
After long wait for the clamps as shown, I could not figure out how to use these clamps. it is so hard to mount it because I could not see points I could stable it. Claudio, could you help out how could mount the clamps to fix the back?
From my heart, I thought I might be better off start another new back than fix this spilt one... however, I have to try anyway

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Messaggio da claudio » venerdì 19 agosto 2005, 17:42

yes, it's better to start with another new back. You can try to fix the old back, of course, but there is not an exact process. You have to try different possible solutions. First, fix the precision clamps at the heads of the back, then you apply the clamps in the above photo. Remember: the new joint doesn't need of strength, don't tight your clamps, just apply them to hold your back in the right position.
Very important: try to make some other joints until you will be confident with your glue and glueing process. Try it on spruce and maple pieces and then try to split the joints.

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Messaggio da tsenglo » venerdì 19 agosto 2005, 17:49

claudio ha scritto:yes, it's better to start with another new back. You can try to fix the old back, of course, but there is not an exact process. You have to try different possible solutions. First, fix the precision clamps at the heads of the back, then you apply the clamps in the above photo. Remember: the new joint doesn't need of strength, don't tight your clamps, just apply them to hold your back in the right position.
Very important: try to make some other joints until you will be confident with your glue and glueing process. Try it on spruce and maple pieces and then try to split the joints.

Yes, I now must admit it will be better off with new back, while I should experiment this old back for the glue strength test.

Thanks Claudio

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Messaggio da Toad » lunedì 6 marzo 2006, 10:55

Where did you guys buy that carving board?

I don't know if I could get used to the ball but the board looks very great.

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