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Prior to making my first guitar, I am starting to build a Fox bending machine. For the top profile, I am using a Stu-Mac plastic top template as a guide. For the body mold as used in the machine, it occured to me that it might be necessary to subtract the thickness of the side material from the tracing left by the plastic template?
I have done a good bit of research on the web, but nobody has indicated if the size of the mold is all that critical. I would appreciate any advice form the more experienced members.
TIA
Len

Take a look at this thread.

viewtopic.php?f=10117&t=25523

It will actually give you a link for the real thread.

Here is another for when you get to the outside mold.
viewtopic.php?f=10117&t=25522

I made my first set of molds from these instructions modifying them to be what I thought was better. As it turned out when I remade them, I followed this exactly. The guidance is spot on.

Thanks again Todd.

Good luck and welcome Len.

Hi Todd
Talk about a wealth of information!! I suspect that I will be spending alot of time at the computer before butchering any more wood. I found at least one tutorial.....which happened to be your article on full thickness inside molds. That appears to answer my question. I like the method of using the proper sized washer against the outside mold to account for the thickness of the stack. Still haven't decided wether to use bulbs or a blanket as a source of heat. I still need (want) a reciprocating drum sander which will be making a call on the credit card .
Thanks for steering me towards the tutorial section.

Len

Len: Suggest you strongly consider a blanket rather then light bulbs.Less fuss and more even heat. Good luck on the new adventure.
Tom

_________________
A person who has never made a mistake has never made anything!!!

I may be the odd man out here, but I approach it differently. It's very difficult to make accurate outside molds without having made the inside master first. I find that it's very hard to feel how smooth the actual trend of a curve is on an inside curve, whereas its very easy to feel if there is some kind of segmentation on an outside curve. Consequently, I make a half pattern interior master out of 3/4" MDF that I check scrupulously for any irregularities. I then make a temporary master for the outside mold that is the exact size on the outside surface, but is about .125" undersized on the inside. I wax my half pattern to protect it, I butter the inside of the temporary master with bondo and push the two together, aligning the centerlines. I hold it until the bondo sets, cut any of the partially set bond off the flat surface with a putty knife, and pull the interior master away. Once the bondo is hard, I do a little clean up on it because it never is a perfect surface, and repeat the process if necessary to fill any voids. I then make a permanent master off another blank which is set aside in the event that I want to make another collar. It is from that master that I make the pieces for the actual mold, routing another piece, stacking and gluing two oversized pieces to it and routing them off and repeating until I have the height I want.

For bending forms, I merely make a copy of my interior mold, rabbit off the compensation I need for slats, sides and blanket, and finish the cut with a pattern cutting bit. A little clean up and you've got a master for the side bender.

I've made my molds and bending molds off the body template and using an inlay routing collar kit along with other collars. There's a pictorial tut in MIMF.com Library. It's also the same technic I used to make my tuning machine buttons jigs and claim shell bridge jigs. Same idea as making a Dutchman patch.
Once you have established a body template you can make a template from it to make a perfect match outside mold template.
The same template can be used to make copies of the body template too if you should break the original.
I'm all for a good body template too.

My thanks to all who have replied. I have lots of info to digest before doing any serious cutting. I suspect that the next step will be to decide on a suitable reciprocating drum sander. I am leaning towards the machine from Jet with the Ridgid running a close second. Beside finishing off guitar molds, the sander will take the pain out of the job I dislike the most, namely finish profiling banjo pegheads.

Len

This has caught my eye if you are referring to a spindle sander.
http://www.grizzly.com/products/1-3-HP- ... nder/G0538

If I remember correctly, FWW rated the Jet as best overall and the ridgid as best value. It may be worth the trouble to dig through my pile of FWW magazines and reread the reviews. I almost forgot about Grizzly. They have a rather complete selection of sanders. The three brands mentioned have ability to use 1/2" sleeves.
In some of the online reviews, owners of the Ridgid mentioned dificulty in finding sleeves. Apparently, not all Home Depot stores carry the sleeves. The 4 1/2" Grizzly sleeves should work. At the weight if #37, I wonder if the Grizzly has a vibration problem.

Len

PS: found the review in the FWW 2008 tool Guide. The Ridgid was judged best value and best overall.

..............." Ridgid is a pretty good bet"...........

I agree. Today I went to the big orange store and came home with the Ridgid sander and a sheet of MDF. I thought my little Hyundai might choke on the load but we made it. Had to cut the MDF into a number of sheets so they would fit in the back seat.

Len