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Plywood or MDF? What do you use for various molds. Any advantage of one over the other.

Thanks.

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Wisdom is justified by her children

Mark,

I prefer birch plywood, but MDF seems to work just as well. I just prefer to work with ply over MDF.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

This observation will count for nothing, but I'll make it anyway: The prettiest, cleanest molds by far that I've seen in these threads are all MDF. I made an MDF mold for laminating a banjo rim. Having worked with it, I can say in my personal experience that plywood, while much less attractive, is a lot stiffer and less prone to distortion under clamping pressure.

...but remember, I said that was just my personal experience.

Patrick

My first molds were MDF and were heavy and ugly.
I too try not to use MDF anymore.
My current mold is birch ply with a coat of amber shellac.
Seems to be much lighter, is certainly stiff enough, and looks great:

MDF is way heavier than plywood, very susceptible to moisture, and so dusty when cutting. yuck.
I specifically use Baltic Birch Plywood. It has many more layers than, and is pricier than standard birch plywood, but more stable and attractive.

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Dee Tee

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"If something is worth doing, it's worth doing right."

Thanks guys. I have plywood ones now and will probably stay with that.

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Wisdom is justified by her children

fwiw - I've used both and have settled on MDF because it is inexpenstive, easy to cut, and seems to hold up OK for the few guitars that I'll build in each mold. I cut four pieces at the same time by bolting them together with flat head machine bolts, and if I am careful, the inside pieces become the molds for my Fox bender, the outsides the building mold. The saw blade kerf and my clean up sanding seem to be about equal to the thickness of the sides.

If I was in production and wanted the molds to last a long time I would probably use plywood.

OK, for some of use that are acronym illiterate what is MDF?

Thanks,

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Joe

My wife asks me "How many Guitars do you need?"
I reply "When I die count them; thats how many I needed".

MDF- Medium Density Fiberboard
MDF-Much Dust Flying

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Wisdom is justified by her children

Thanks Mark, it seems that I am acronym challenged. Is there a listing for all the acronyms used on this site? Some I have figured out, most I don’t.

Thanks,

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Joe

My wife asks me "How many Guitars do you need?"
I reply "When I die count them; thats how many I needed".

I use the cheapest plywood I can find. They may not be the prettiest molds but they work fine. Cheap plywood is plenty strong and stable enough. I cover the mold inside and out with a layer of packing tape. That eliminates any splinters or problems with pitch-staining.

I suppose if I built dozens of copies per year I'd upgrade to nicer materials.

So, Hm. Dep. B side,C side 5/8"x 4'x8' plywood would be OK for molds. I think right now if I make Two guitars this year I will be very happy.

Thanks,

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Joe

My wife asks me "How many Guitars do you need?"
I reply "When I die count them; thats how many I needed".

This is a little late but I have used typical building grade plywood from the home center since finding quality multiply birch is easy in the city. I have also used the hardwood plywood that is sold at home depot and lowes. Which has a veeneer of birch or oak over a core that I believe may be Lauan or something similar. I'm planning on trying MDF next. Also don't forget to seal your molds. I know some people who don't but I think it is important. I use the Zinsser Bullseys SealCoat.

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Another day, another dollar.

I decided not to scrimp and bought the birch...It looks like 8 ply around $50.00 a sheet. Will seal it with zpoxy.

Joe H.

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Joe

My wife asks me "How many Guitars do you need?"
I reply "When I die count them; thats how many I needed".

Way to go. Did the same myself.

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Wisdom is justified by her children

I like baltic birch.