So im in the middle of building a tool for a new boat. I thought I would keep a small journal of various steps along the way. Recently, I finally got my hands on some webspace to host this journal. I will update the page every week or so hopefully, please feel free to e-mail me with some comments. My construction methods are a little bit different then main stream, but works well for me.
Right off the bat, I will say, the work I am doing can be done better by a CNC machine or the likes, but I dont have the several grand to invest in that kind of tooling!!!
Matt, I was worried about shaping the mdf, and actually started in on this not knowing if it would work. . . At first I thought I was going to have to use half inch MDF which would have not worked very well as the resolution between layers would not have been to good, which would have resulted in ALOT of inaccurate sanding. The God sent was finding the quarter inch thick MDF. Much higher resolution and much easier sanding, and a lot less sanding. It was alot of fun. I decide I was going to build the hull shape on a wednesday . . . and with only 4-5 hours of work over 3 days, showed up at a race that weekend to show the already shaped plug to some of the people I sail with. their comment. . . you started that wednesday?!?!?
If the mold builds up as expected, I will probably turn around and try to shape a marblehead plug before the snow flies! (I work out side to avoid cleaning up!)
One should be careful sanding MDF, as it contains more or less amounts of formaldehyde and the dust can be highly flammable. No big deal, just use common sense WRT a dust mask and keeping the workspace clean. Some people get allergic reactions to dust as well, generally from getting it in their eyes.
One other note: if you use a structural foam like Last-a-Foam (same cautions, plus do not use hot wire cutting, the fumes are toxic), put a layer of glass on the outside and scoop out the inside, you’ll have a completed hull. This is the Bert Rutan “fly the plug” system
One should be careful sanding MDF, as it contains more or less amounts of formaldehyde and the dust can be highly flammable. No big deal, just use common sense WRT a dust mask and keeping the workspace clean. Some people get allergic reactions to dust as well, generally from getting it in their eyes.
One other note: if you use a structural foam like Last-a-Foam (same cautions, plus do not use hot wire cutting, the fumes are toxic), put a layer of glass on the outside and scoop out the inside, you’ll have a completed hull. This is the Bert Rutan “fly the plug” system
todd
have you tought of using mudd, to fill in the low spots of your hull. since you are basicly using drywall for your mold. why not use the mudd that the builders use to hide seam lines. it sand smooth and almost comes to a glass finish?
cougar
todd
have you tought of using mudd, to fill in the low spots of your hull. since you are basicly using drywall for your mold.
cougar
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I’m confused, I thought MDF works more like wood, was more of a wood substitute than drywall or sheetrock. Which is basically plaster between two sheets of paper.
doc-
mdf is, in essence, what we used to refer as “particle board”. basically it is wood shavings/sawdust combined with resin, pressed tightly together and cooked. i would not suggest using drywall compound with it as the lime in the drywall compound (which is used for drying and curing) combined with the water make-up, can deform and and break down the resins in the mdf leading to failure of a smooth surface.
the best thing to use is a plasticized body filler type material (i.e. bondo)
John Storrow. Well be able to build a couple of these without breaking the bank. By the end of winter I hope to have molds for all the moldable parts
(hull, deck, rudder, keel, radio board, main boom and jib boom, and integral keel trunk/mast step)
All it will cost us to crank out a couple is the cost of the materials and then some (but not too much) assembly time. If all goes as plans, all parts should come out of the molds and ALMOST just fall together! And I am sure we can do this for short money (I try to take care of those I sail with).
Fly the plug method. . . too heavy and the quality isnt the same as what you can get out of a mold or molding plug. I have tried it in the past, and it is worth the effort to build the higher quality plug and pull real parts off of it.
Body filler/ drywall mud. . . . MDF is NOT drywall! it is MUCH MUCH denser and made as stated by skiffy I believe from saw dust and resin. It shapes wonderfully and since it is not as soft as foams or balsa, it is much harder to make a low spot. Also because the metod does NOT use stations like plank on frame the piece is solid throughout without the soft spots where you can dip down between frames like in foam. The 2 spots I elected to use alittle filler. . . west system, mixed with a little coldilla silica works perfectly and has about the same sanding properties as the mdf. Works nicely. If you use to strong of a filler to fix a low spot, when you go to fair in the fix, you will make a new low spot around the harder material. . . How to avoid this. . . dont make low spots in the first place.
Sorry I havent posted more HTML on the project, I have been pretty busy with some other projects and the deck plug, which I wont bore you with the construction of, but might post a picture of it at some point.
Tod-
I have a program called Prolines which you probably have or heard of, but It doesn’t print to scale. Its great for designing hulls, but useless for building from. I also have AutoCad Lt which I can build from, but is time consuming to plot so many lift lines one point at a time. I was curious how you design yours?
I have another one called Carene or something like that but it only does “Strakes” which you then have to transfer to Cad, and laboriously plot lift lines anyway.
Thanks again!!
i am sorry about the posting of the mudd. it is wrong, I thought you were using drywall not mdf forget what i said.
like i said sorry about the mix up
cougar
John, What I currently have access to is SDRC ideas which is rediculously expensive but very powerful. Printing out sections is fairly easy. That being said, I know that I could use the same method in Solid Works as well and get the same results. Any of the slightly more robust solid modeling packages will allow you to make the hull shape just fine, its then up to you what to do with the hull shape. Different analysis packages etc etc. I hope that answers your question.
tb
have youu ever tried the program called inttelicad. i use it for designing my boats now , it is much easier to use than autocad and model cad, I tried maxisurf and did not like it. i got my copy from a friend, you could try and download a version of it. we sailors who like nzl 32 should stick together
cougar
