Arching Plaster Casts

[scordatura]

Valient effort Jackson. He doesn't understand nor will he understand.

It would be nice to have more accessibility to casts or ct scans to 3d print. There has been some talk on MN in the past but no traction thus far. My own efforts with cad modeling (fusion 360) have stalled because I am busy with other things. Hope to get back to it soon.

[MikeC]

I have 3D printable files. I don't have a 3D printer though.  A friend of mine has one and I asked him to print it for me but he never did get back with me on that.   

[Dennis J]

For what it is worth I've never said there is no value in examining early makers' arching profiles. Doing so confirms my belief that what I'm doing is consistent with those profiles.

The arching height and inflection point at each cross-arch position largely determines the shape of the arching profile. That's why I say there is nothing special about any particular maker's arching.

 

 

 

[scordatura]

4 hours ago, MikeC said:

I have 3D printable files. I don't have a 3D printer though.  A friend of mine has one and I asked him to print it for me but he never did get back with me on that.   

The problem with 3d printing is that for a full plate on some printers, it is too large to print. It must be done in pieces which is not an impossible task. Scrolls are much easier. I might be willing to have a go at it MikeC as I have access to a 3D printer and a CNC machine. Send me a PM.

[MikeC]

1 hour ago, scordatura said:

The problem with 3d printing is that for a full plate on some printers, it is too large to print. It must be done in pieces which is not an impossible task. Scrolls are much easier. I might be willing to have a go at it MikeC as I have access to a 3D printer and a CNC machine. Send me a PM.

I'll send you a PM tonight.  I'll have to find my files.  I had cut one file to only have the lower part of the F hole area which is what I was mainly interested in.   Maybe I can upload to dropbox and share a link.   

[Nikos Matsablokos]

18 hours ago, MikeC said:

I'll send you a PM tonight.  I'll have to find my files.  I had cut one file to only have the lower part of the F hole area which is what I was mainly interested in.   Maybe I can upload to dropbox and share a link.   

If you could upload it here via a dropbox link, it would be extremely helpful for me as well, since I have a 3d printer and use it a lot in my work when possible. Thanks in advance 

[MikeC]

1 hour ago, Nikos Matsablokos said:

If you could upload it here via a dropbox link, it would be extremely helpful for me as well, since I have a 3d printer and use it a lot in my work when possible. Thanks in advance 

I'll post a link this evening when I get home from work 

[MikeC]

I may be able to post the file directly here I'm not sure.  I'll try that too.   It's the Stradivari Betts and as I recall I found it somewhere here on MN in another thread but I don't remember which one. 

[GerardM]

4 hours ago, MikeC said:

I may be able to post the file directly here I'm not sure.  I'll try that too.   It's the Stradivari Betts and as I recall I found it somewhere here on MN in another thread but I don't remember which one. 

When it’s printed will it be an exact front and back replica of the Betts violin?

[Nikos Matsablokos]

1 hour ago, GerardM said:

When it’s printed will it be an exact front and back replica of the Betts violin?

In theory if the file is accurate the deviation that you might expect from a properly set printer is about half the line width and half the layer height so i'd say about 0.1-0.2 mm deviation from the real model. That's the uncertainty due to how the printed lines get stacked on top of each other to form whatever you are printing. Also some very minor rounding of very sharp corners might take place. Other than that its pretty accurate and I always use my 3d printer to make templates.  Using pictures either scanned from the Strad Posters or from Tarisio (After I scale them of course)

[Urban Luthier]

On 3/8/2022 at 7:07 AM, Dennis J said:

What's so special about Strad arching. It's much like any other competent maker's arching of the time. How does it differ to other makers' work?

I'm sure they knew the basic geometry of arching and applied that in their work. At least some of them did.

Really? Amati family, Strad, Guarneri family, Bergonzi archings are all different. Even strad varied his arching radically over his career - look at the Tuscan from 1690 vs a golden period vs a late period. 

I wish I could have afforded the Amati plaster casts auctioned at the Last T2. For me it is less about copying and more about studying how the maker resolved geometric transitions as well as getting an overall view of arching as a whole. The ability shine an anglepoise lamp over a plaster cast, would be a valuable study aid -- for me at least. 

[Dennis J]

13 hours ago, Urban Luthier said:

Really? Amati family, Strad, Guarneri family, Bergonzi archings are all different. Even strad varied his arching radically over his career - look at the Tuscan from 1690 vs a golden period vs a late period. 

I wish I could have afforded the Amati plaster casts auctioned at the Last T2. For me it is less about copying and more about studying how the maker resolved geometric transitions as well as getting an overall view of arching as a whole. The ability shine an anglepoise lamp over a plaster cast, would be a valuable study aid -- for me at least. 

I've never said arching among makers didn't vary. It's quite obvious it did, mainly in height and the ratio of upper convex and lower concave ratios of curvature. Once those parameters are set the arching profile is also.

You can experiment yourself. Mark a top centre position on a vertical line at say 15 mm above a horizontal line. Then draw a horizontal representing an edge height of about 4 mm. Then mark an inflection point (blue dot) about 3 mm above edge height and 50 mm from the vertical centre line. If you change the position of the inflection point you will change the shape of the compound curve. And if you move it too far on the horizontal or vertical axis it becomes impossible to draw a smooth arch profile. So the inflection point is set at the optimum place here. The pic shows the lower corner cross arch.

[MikeC]

13 hours ago, Nikos Matsablokos said:

If you could upload it here via a dropbox link, it would be extremely helpful for me as well, since I have a 3d printer and use it a lot in my work when possible. Thanks in advance 

Here are my dropbox links.   If these don't work I could try to upload the files here.  I don't know if it's possible to upload the files here but I could try it.   I found these and some other 3D files here on MN back some time ago but don't remember what thread.  

https://www.dropbox.com/s/kurmqoztk7hxkae/violinmidsectionbinary.stl?dl=0

https://www.dropbox.com/s/bhwrkq5mqgorxw1/Betts_FP_StlFromDICOM.stl?dl=0

 

[GerardM]

16 hours ago, Nikos Matsablokos said:

In theory if the file is accurate the deviation that you might expect from a properly set printer is about half the line width and half the layer height so i'd say about 0.1-0.2 mm deviation from the real model. That's the uncertainty due to how the printed lines get stacked on top of each other to form whatever you are printing. Also some very minor rounding of very sharp corners might take place. Other than that its pretty accurate and I always use my 3d printer to make templates.  Using pictures either scanned from the Strad Posters or from Tarisio (After I scale them of course)

If the printing is successful would it be possible to make a sett for me. I will  pay the expense to print and any postage costs.

[GerardM]

Plus of course any profit margin you wish to add.

[Michael Szyper]

What happened to this great forum…

[Nikos Matsablokos]

3 hours ago, GerardM said:

Plus of course any profit margin you wish to add.

I am afraid I don't really have the time to do so, since such long prints require attendance and often might fail. Not to mention that you can't 3d print the whole thing at once unless if its a neck. You'd have to print it, in sever parts and then glue them together.

May I suggest to search for places that offer 3d printing services near you. There are a lot of them anywhere in the world,  and they'll have a much better printer than mine and will probably produce a better result than I ever will.

[GerardM]

2 hours ago, Nikos Matsablokos said:

I am afraid I don't really have the time to do so, since such long prints require attendance and often might fail. Not to mention that you can't 3d print the whole thing at once unless if its a neck. You'd have to print it, in sever parts and then glue them together.

May I suggest to search for places that offer 3d printing services near you. There are a lot of them anywhere in the world,  and they'll have a much better printer than mine and will probably produce a better result than I ever will.

Thank you for the Explanation Nikos, having no experience of 3D printers I now understand the complexities involved. Thank you again.

[Nikos Matsablokos]

3 hours ago, GerardM said:

Thank you for the Explanation Nikos, having no experience of 3D printers I now understand the complexities involved. Thank you again.

No problem  Its a great machine that can be very useful, even around a luthiers workshop. I use it to print templates, tools (clamps, custom sanding blocks and many other things that can be useful in our craft). I wish more violin scans where made available to 3d print since they are a great alternative to plaster casts and unlike the plaster casts, which require the actual violin every time you want to make them, 3d printed versions only require the violin to be scanned once and then you can print the scanned instrument as many times as you like. Hopefully some day more scans will be made available.

[Advocatus Diaboli]

i.materialize.com

[Advocatus Diaboli]

I realize now that might have seemed like a spam post, but it’s just a link to an online 3d printing service. 

[Urban Luthier]

I correspond with Andrea Zanre when S&Z published the Tuscan strad book. They originally offered 3d printed plates as an option when purchasing the book. They were unapply with the prototypes (apparently .5 mm) off and withdrew the option.