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MDF and mold pattern


Rich

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If you can stand it, 1/2 inch MDF is fine. I have a thing against MDF. A thickness of 1/2 inch will allow you sufficient extra clearance below the linings.

By "button polish" do you mean button lac? As in shellac provided in "button" form, ie: little round disks? If so, here is a good page that talks about shellac, including button lac, which is the first refinement of seedlac, cast into little disks.

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Sure. I put polyurethane finish on mine. I'm not worried if Stradivari had polyurethane for his moulds or not. On the other hand, he didn't have MDF. The reason I don't like MDF is the dust you get while sanding or filing it. I used a piece of cherry lumber for my second mould, planed down to 1/2". I like the way it behaved under the file, and I like the way it looks. And it cost me maybe a buck or two.

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I just bought an 8' section of this stuff this afternoon for making a workbench. It's 1.5" thick. Are you finding 1/2" thick butcherblock where you live, or do you propose to plane some thicker stuff down to 1/2"? Personally I think using that would be more complex than it's worth. What's wrong with a simple maple or cherry (or some other hardwood) board? For that matter, plenty of people use MDF, but I personally won't use it because I don't really like it. I'm not sure what advantage will be gained by going with butcherblock. Although if you do make a mould out of butcherblock, please take a picture of it and post it for us all to marvel at.

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I looked for cherry at a hardwood specialty shop. All they would sell me was a 6 foot long piece for $43 Canadian. Too much. My maintenance man at school said he had cutting board. Also, would joining two pieces of oak with a doweling jig work? I just can't get into $43 for cherry...and really would like to find a way to use hardwood. I could get narrower oak.

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I have used 16mm MDF for my molds and it seems to have worked well so far. I'm not sure how long it will last though, but it is cheap enough to make new molds after every third violin or so. I have my MDF laser cut from a pattern I did on AutoCAD, that way I can be sure I get consistancy on my garlands. My molds are also demounatble which helps when I remove the mold.

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To date (7 acoustics) I have finished the bass bar to about 80-90% before gluing. I know I should do more shaping once it has been glued in but I have made sure of a 100% fit. I am still trying to find out more about plate tuning, once I have a definitive way I may have to do more shaping afterwards.

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Where do you get access to laser cutting? If you spend the extra effort to do the laser cutting, why not use some material that is more durable? It looks very clean. Nice work...

For the bass bar, how do you clamp the bar during gluing? The shape is already irregular. How do you fit the clamp on the bass bar? When you apply pressure, does the clamp damage the shape of the bass bar? What is the advantage of shaping the bass bar before gluing?

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I laser cut because that way I can be sure of accuracy - just my nature. I use MDF because I have a factory full of it (audio support furniture is my main business) but at some point, when I think I have the "perfect" shape, I will probably have it cut in a more durable material. Also, I design/make "alternative" shaped violins which I refine from time to time and MDF is cheap enough to throw away when I make a modification. These alternative violins (see my website if you are curious) are made for fun and to satisfy my need to design stuff. More importantly, young people who would not normally be interested in violin playing are attracted by the modern shapes and translucent colours I offer. They do not sound too bad either and the geometry is correct but I can see Stradivari turning in his grave:-)

The bass bar clamping is not easy but I manage somehow using specially shaped jigs. Final shaping/smoothing is done after glueing. You may have noticed that my plates are pretty close to being finished before assembly too. I finish all parts with upto 400 grit paper before assembly and if I need to make some later repairs or adjustments it's not too serious.

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Amori, I believe the most obvious example, and what I believe Dean was probably referring to, was the picture on the far left of the row of acoustic instrument pics, labeled "model 1 traditional colour". The fingerboard doesn't seem to have the traditional scoop, by which is meant a "U" shaped trough between the ends of the board. Ie: if you lay a straightedge from the bridge end of the board to the nut end, the fingerboard will fall down below the straightedge between these points. Your board also seems a bit thick at the nut end.

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