Building a Cutter

[Bob Cleek]

Those are very good methods, indeed, however. I don't use them, anymore, because I found that bending my frames around the forms using heat tends to make for a shape more prone to staying 'set' after pulling the hull off of the mold. Not much 'spring' at all. Obviously, cling wrap and wax won't play nice with the heat. The wax melts into the wood making it impossible to get good internal glue joints, after the fact. The cling wrap just shrivels up towards the iron and makes a mess. That's just the way that 'I' do it. That doesn't mean that it is 'the' way for everyone else...

Excellent point! I never encountered that issue and never thought about it because I always pre-bend my frames off the molds "by eye" and "over-bend" them a tiny bit too tightly so that they will have a bit of tension to "spring" them against the mold when pressed into the retaining holes on the baseboard. I use an Aeropiccola bending iron rather than soaking in warm water, so with the hotter bending iron they tend to have less spring-back when bent, or so it seems. I also install my frames full-length from side to side, sometimes with a keelson to which they are attached let into a slot in the molds and then the keel laid over the inverted hull when all the frames are set up. I ended up doing it that way with a "mold release barrier" on the molds because when I first tried this framing technique, my sloppy gluing resulted in my having to bust up the hull to get it off the molds on my first attempt!

 

[MThomas]

I use an Aeropiccola bending iron rather than soaking in warm water, so with the hotter bending iron they tend to have less spring-back when bent, or so it seems.

Bob, I'm not familiar with that particular bending iron, at least I don't think so. For all I know I have one in my tool bin and use it often. I've had many styles of irons throughout the years and most all of them seem to have their own unique shortcomings, as is the case with most everything else we buy. I find certain style irons good for certain situations, and I regularly switch up and use 'whatever' iron as needed for whatever curious task fits it best. As for the water thing? I typically use hard woods and like to pre-soak everything to be bent for at least 24 hours prior to bending. Sometimes for a couple days if I don't feel like working with it the day after. That extended time doesn't hurt a thing. This soaking doesn't actually soften 'hard' wood, nor make it bend easier at all. What the soaking does, for harder woods, is to give the applied bending heat a good medium upon which to travel through/upon. Hot water does not bend hard wood; really hot heat does! The water is simply a good conductor of heat. It turns to steam, inside the wood and drives the heat deep, quickly.
I'm currently working on a launch that will have exposed frames. I've soaked those frames, hot bent them over the former bulkheads... and when I'm through planking, I'll go over those exposed frames, again, with a small hot iron, just to be safe prior to releasing the hull from the buck. Probably not necessary at all, it's just a confidence thing, LOL.

 

[Namabiiru]

Allen, I’m following this with interest, having never felt quite up to the task of a scratchbuild before. I’d like to dip my toe in the water by scaling your drawings (with your kind permission) down for a small boat for the Gallic Thonier on which I’m nearing completion. However, your drawings and moulds are in different file types so when I save and print them, they don’t come out to the same scale. Is there a common reference between the two that can be used to adjust them to the same scale?

 

[AllanKP69]

I’d like to dip my toe in the water by scaling your drawings

I take your request as a compliment, thank you kindly. All my drawings are available to any member, so it is my pleasure to help. I usually print them from my CAD program so they are printed at the scale on the drawing. What scale do you need? I can size the drawings to whatever scale you would like and add a scale rule on the drawing so you can check it when you have it printed. I can save the drawings in a number of extensions but CAD extensions and PDF are great in my experience. If you have a CAD program I can send as DWG or DXF or TCW. If not, will PDF be OK? I'll add a scale bar to each drawing so you can check that the printed copies you make will be correct. This will take a bit of time as I have everything on one large drawing so I will need to break it down into pages of 8.5X11 or whatever size paper you will be using.

Allan

 

[Bob Cleek]

Bob, I'm not familiar with that particular bending iron, at least I don't think so.

The Aeropiccola electric plank bender, also known as the Ralt RA5 plank bender, was manufactured by Aeropiccola Modelissmo, an Italian model company. Production ceased when Aeropiccola went out of business about thiry years ago. Since then, this plank bender has become somewhat of a treasured "Holy Grail" ship modeling tool. They do appear on eBay with some regularity. Knowledgeable reviewers have considered it the best electric plank bender ever made. It was widely popular with ship modelers and remains so for those who own one.

Uniquely, the head is cast in a Fibonacci curve ("golden ratio" or "French curve") shape. It has two holes in which can be mounted a spring-loaded roller bail. This permits stock to be held against the heated head curve and progressively bent with one hand as it is fed under the bail which holds the piece against the hot head. The alternate bail mounting holes permit shaping to various curve radii. The bail can also be removed completely and the head face pressed against a workpiece, as in shaping plank against a framed hull. The bail permits use with one hand holding the tool's handle and the other shaping the workpiece. The tool may also be held in a vise with both hands free to handle the workpiece. The handle is just a standard soldering iron.

 

[AllanKP69]

This soaking doesn't actually soften 'hard' wood, nor make it bend easier at all. What the soaking does, for harder woods, is to give the applied bending heat a good medium upon which to travel through/upon. Hot water does not bend hard wood; really hot heat does!

This is probably all true but I did a test this morning. I soaked a couple pieces of Castello box that were 0.04X0.04" overnight. They bent, at room temperature, around a two inch diameter jar without breaking. I tried several dry pieces of the same size and every one of them broke before they were halfway around. No heat was applied, just water at room temperature.

I had used soaked holly for the frames on this project so cut a couple pieces during this morning's test and then tried bending them dry. 2 out of 4 broke.

Based on my very limited test, for the species and sizes I tried, wood becomes soft/pliable/easy to bend when soaked and breaks when dry.

Allan

 

[RussF]

Those are very good methods, indeed, however. I don't use them, anymore, because I found that bending my frames around the forms using heat tends to make for a shape more prone to staying 'set' after pulling the hull off of the mold. Not much 'spring' at all. Obviously, cling wrap and wax won't play nice with the heat. The wax melts into the wood making it impossible to get good internal glue joints, after the fact. The cling wrap just shrivels up towards the iron and makes a mess. That's just the way that 'I' do it. That doesn't mean that it is 'the' way for everyone else...

I've built a couple of full sized cedar strip canoes and found that just putting a layer of regular masking tape on the edges of the forms prevents glue from sticking to them. The heat won't bother it either.

 

[AllanKP69]

I've built a couple of full sized cedar strip canoes and found that just putting a layer of regular masking tape on the edges of the forms prevents glue from sticking

That is one I am going to try, Masking tape, not duct tape?
Thanks Russ
Allan

 

[RussF]

That is one I am going to try, Masking tape, not duct tape?
Thanks Russ
Allan

Yup. Plain old masking tape has a waxy coating on it and glue pops right off.

 

[Namabiiru]

I take your request as a compliment, thank you kindly. All my drawings are available to any member, so it is my pleasure to help. I usually print them from my CAD program so they are printed at the scale on the drawing. What scale do you need? I can size the drawings to whatever scale you would like and add a scale rule on the drawing so you can check it when you have it printed. I can save the drawings in a number of extensions but CAD extensions and PDF are great in my experience. If you have a CAD program I can send as DWG or DXF or TCW. If not, will PDF be OK? I'll add a scale bar to each drawing so you can check that the printed copies you make will be correct. This will take a bit of time as I have everything on one large drawing so I will need to break it down into pages of 8.5X11 or whatever size paper you will be using.

Allan

Allan,
That is very kind. A scale on the drawing and moulds would be very useful. For scale, it’s going to be trial and error. The model I have is 1:50, but your 1:36 cutter reduced to 1:50 will still probably be too big. It’s anathema to say it, but I figured I’d use the TLAR method to scale it to something that looks “about right”. Obviously, tuna boats didn't have cutters, but I’m using some artistic license. I have no CAD more advanced than Google Sketchup, but I do most design in Powerpoint anyway…

 

[MThomas]

Yup. Plain old masking tape has a waxy coating on it and glue pops right off.

I use the blue painter's tape.

 

[MThomas]

The Aeropiccola electric plank bender, also known as the Ralt RA5 plank bender, was manufactured by Aeropiccola Modelissmo, an Italian model company.

Yep, I've got one! Now that I see it, I know which one you are talking about!

 

[MThomas]

I wonder how much 'this' one springs when it comes off of the form!

 

[AllanKP69]

I wonder how much 'this' one springs when it comes off of the form!

I hope this will come out of the room. Reminds me of Jethro Gibbs' boats on the NCIS TV series.
Allan

 

[AllanKP69]

The model I have is 1:50, but your 1:36 cutter reduced to 1:50 will still probably be too big.

If you want the drawings scaled down, I only need to know one key dimension such as LOA, breadth or something similar and can make it to any scale you want.
Adding a reference scale is no problem. The one below is four inches long.
Allan

 

[MThomas]

Namabiiru,

Allan can scale this thing down too small for you to even build, if you like! Size is no problem. Give Allen the overall length you desire, and he can scale it to that size in the blink of an eye using CAD.

 

[Namabiiru]

I can scale it as well. The issue I have is making sure the moulds and the plans are at the same scale after I have saved them from the site. I know they are the same scale on Allen’s system, but on this thread, one is a JPG and the other a PNG. Consequently, my image software handles them differently after I’ve saved them to my hard drive so I’m not starting with them at the same scale. Having the scale printed on both would allow me to get them sized the same. I greatly appreciate Allen’s willingness to go to the trouble of doing that.

 

[MThomas]

Yep, as long as he puts that scale reference on the drawing(s) you can't go wrong!

I recently had to scan a lot of drawings to my HD. When I opened them up, they were all off by a little bit and no two of them were off the same amount. Thanks to my putting a 12" scale reference line on the drawings I was able to adjust each individual drawing to proper dimensions.

 

[Bob Cleek]

I wonder how much 'this' one springs when it comes off of the form!

View attachment 528837

And I'm wondering whether it's going to bust a bunch of frames if it does move when it comes off the form. Those frames don't have much meat on them and they're full of fasteners. A thicker sheer strake and clamp boxed with a cap rail should add a lot of structural rigidity, though.

 

[AnobiumPunctatum]

I can scale it as well. The issue I have is making sure the moulds and the plans are at the same scale after I have saved them from the site. I know they are the same scale on Allen’s system, but on this thread, one is a JPG and the other a PNG. Consequently, my image software handles them differently after I’ve saved them to my hard drive so I’m not starting with them at the same scale. Having the scale printed on both would allow me to get them sized the same. I greatly appreciate Allen’s willingness to go to the trouble of doing that.

Do not work with the downloaded files. It is an easy task to print the mouldes and all other details from a cad file as PDF. The only thing to remember is that you have to print the PDF with 100% size.
If you need help there, I can assist you.