Several weeks ago I got a good deal on some Aspen plywood. I picked up a couple of sheets of 3/4" for the strong back, and a couple of sheets of 1/2" for the station molds. I brought it home and to save space stood it up against the wall. A mistake I suspect.
When I started 2 weeks ago, I discovered the 1/2" had cupped. I laid it out flat with several 2x4's underneath to keep is off the concrete floor. It has settled somewhat, but not enough for accurate molds I am thinking.
Any suggestions? or do i save it for other uses, and go and buy some MDF?
The 3/4" Aspen worked nicely for the strong back, is just about complete except for final positioning and leveling.
Dave
Aspen plywood for station molds
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Davesbuild
- Posts: 52
- Joined: Mon Aug 25, 2008 5:51 pm
- Location: Peterborough, Ontario, Canada
- Contact:
DaveA
As you are aware, I'm building the Huron Cruiser. I am using molds that I have borrowed from my cousin. His attempt at the stripper wasn't so good (he gave up after putting on the first 4 (or 8?) strips - hopefully I can help him, once I go through the process myself), so his 3/4" MDF forms sat for sometime. When I went to set them up on my strongback, I noticed that one stem was significantly warped. I put it in a "workmate" with a couple of well-placed 1/4" strips to deflect some of the warpage - it worked! If that hadn't of worked, I had also thought of reinforcing across the "cupping" in the mold with some 1-1/2" x 1-1/2" strips of hardwood to try to straighten it out. (and keep it straight).
Bent-up stem #1 today! no problems...
Good Luck.
Dave
As you are aware, I'm building the Huron Cruiser. I am using molds that I have borrowed from my cousin. His attempt at the stripper wasn't so good (he gave up after putting on the first 4 (or 8?) strips - hopefully I can help him, once I go through the process myself), so his 3/4" MDF forms sat for sometime. When I went to set them up on my strongback, I noticed that one stem was significantly warped. I put it in a "workmate" with a couple of well-placed 1/4" strips to deflect some of the warpage - it worked! If that hadn't of worked, I had also thought of reinforcing across the "cupping" in the mold with some 1-1/2" x 1-1/2" strips of hardwood to try to straighten it out. (and keep it straight).
Bent-up stem #1 today! no problems...
Good Luck.
Dave
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David James
- Posts: 223
- Joined: Tue May 11, 2004 9:04 pm
- Location: Glenview, Illinois
I guess another Dave might as well chime in here.
Dave, I built both the strongback and forms for my F17 using 3/4" birch plywood. It worked great. I have two more sheets ready for when I start my Rob Roy.
I can't believe a small amount of warping would have any real effect on the final shape of the hull, but ... think of the many hours of time you are about to invest. You'll not want to compromise here. Personally, I would use only unwarped sheets for my forms.
Just my humble opinion.
Dave in Glenview, Illinois
Dave, I built both the strongback and forms for my F17 using 3/4" birch plywood. It worked great. I have two more sheets ready for when I start my Rob Roy.
I can't believe a small amount of warping would have any real effect on the final shape of the hull, but ... think of the many hours of time you are about to invest. You'll not want to compromise here. Personally, I would use only unwarped sheets for my forms.
Just my humble opinion.
Dave in Glenview, Illinois
"If given six hours to chop down a tree, spend the first four sharpening your ax." - Abraham Lincoln
Dave,
Thanks for that, I had considered trying some re-enforce strips. In think with it lying flat, and I light misted the concave side once, it has flatten somewhat. So maybe with some re-enforcing at least some it may be usable. I wanted to get the molds cut this weekend and also start bending the stems. So I will know very shortly if the aspen can be salvaged.
Sounds like you are just ahead of me; please keep up the reports on how your progress.
What kind of wood are you using for you stems? I picked up some cherry yesterday for my outer stems.
Dave
Thanks for that, I had considered trying some re-enforce strips. In think with it lying flat, and I light misted the concave side once, it has flatten somewhat. So maybe with some re-enforcing at least some it may be usable. I wanted to get the molds cut this weekend and also start bending the stems. So I will know very shortly if the aspen can be salvaged.
Sounds like you are just ahead of me; please keep up the reports on how your progress.
What kind of wood are you using for you stems? I picked up some cherry yesterday for my outer stems.
Dave
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Davesbuild
- Posts: 52
- Joined: Mon Aug 25, 2008 5:51 pm
- Location: Peterborough, Ontario, Canada
- Contact:
Hey Dave,
Using Ash for the outer and white cedar for the inner stems. The rest of the trimmings will be cherry. I recently purchased about 70+ B.F. of cherry.. so I have enough to trim afew canoes.. I did consider using the cherry for the outer stems, but changed my mind at the last minute.??? From what I have heard from others, cherry would also be just fine for the outer stems.... my second set of stems are currently drying in te sun - in the form in the laneway on the workmate!
I will likely make a few paddles also...
I have been sorting my strips and "dry-fitting" the first few to see how things go together.
The spraying with some water to straighten the wood is also a good idea. I make traditional hunting / shooting bows also... I've "bent" lots of various woods as "experimenting / engineering" the forces in different woods and various grain alignments.
Dave J - Of course the preference would be to use "straight" wood all the time, but sometimes we just gotta "go with what we got"... my MDF stems are now straight and able to still be used...
Davesbuild
Using Ash for the outer and white cedar for the inner stems. The rest of the trimmings will be cherry. I recently purchased about 70+ B.F. of cherry.. so I have enough to trim afew canoes.. I did consider using the cherry for the outer stems, but changed my mind at the last minute.??? From what I have heard from others, cherry would also be just fine for the outer stems.... my second set of stems are currently drying in te sun - in the form in the laneway on the workmate!
I will likely make a few paddles also...
I have been sorting my strips and "dry-fitting" the first few to see how things go together.
The spraying with some water to straighten the wood is also a good idea. I make traditional hunting / shooting bows also... I've "bent" lots of various woods as "experimenting / engineering" the forces in different woods and various grain alignments.
Dave J - Of course the preference would be to use "straight" wood all the time, but sometimes we just gotta "go with what we got"... my MDF stems are now straight and able to still be used...
Davesbuild
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Glen Smith
- Posts: 3719
- Joined: Sat May 08, 2004 9:08 am
- Location: Baie-St-Paul, Quebec, Canada
For the molds, I prefer to use perfectly flat plywood (or whatever) for the stem forms. For the other forms, a bit of warpage isn't a problem. I have also reinforced and straightened some materials to use as stem forms without any problems. Just don't make the "ribs" too large so they don't interfere with the inner stems and the stripping process.