Scratch building the Alfred Stern

[Dave Stevens (Lumberyard)]

The project begins with tracing the 14 stern frames from Harold Hahn's modeling plans of the Alfred. The frames were scanned as a JPEG file and linked to CAD. Auto Cad does not import files it links to files. Hahn's original Alfred drawinga are in 1/8 scale so i am enlarging the build to 3/16 scale.



i just traced one side of each frame because i can mirror the drawing for the other side, this insures both sides are exactly the same.

 

[Dave Stevens (Lumberyard)]

once the tracings are done the next step is to break down the frames and create a laser cutting file each frame is a different color if i did not do that it would be extremely difficult to figure out what pieces goes to what frame.



now that i cutting file has been created sheets are milled to the proper thickness and off to the laser cutter


looking closeup



i am using laser cutting rather than cutting the parts out with a jig saw or band saw is because i can place the parts very close together thus fitting more parts per sheet. As you can see on the left side how close the parts are to each other.

 

[Dave Stevens (Lumberyard)]

Stop right there!

i am calling this a scratch-built project and right off i am using a set of drawings done by Harold Hahn and i surely did not cut all the frame parts by hand.

OK
first of all no matter what ship your going to build you are starting with an existing drawing. unless it is pure fantasy and your making up a ship. If your going to do that then why not go all the way and build something like this. The only true scratch builder is the master shipwright who designed and built the original ship.



as for the laser cutting, sure i can set here with a fret saw and cut every piece by hand or i can use a power tool and cut the parts with my 10 inch table top bandsaw OR create the laser cutting file and cut the parts with a laser. I did not push the start button on the laser machine the guy who operates the laser did that. Now we are splitting hairs of exactly who did what.

 

[Dave Stevens (Lumberyard)]

there are double and single frames, the doubles are frames W X Y and Z which are made up of 14 parts so there are 2 of each piece



each frame is assembles as shown so the butt joint overlap creating a strong frame.

 

[Don Case]

Stop right there!

i am calling this a scratch-built project and right off i am using a set of drawings done by Harold Hahn and i surely did not cut all the frame parts by hand.

OK
first of all no matter what ship your going to build you are starting with an existing drawing. unless it is pure fantasy and your making up a ship. If your going to do that then why not go all the way and build something like this. The only true scratch builder is the master shipwright who designed and built to original ship.

View attachment 452445

as for the laser cutting, sure i can set here with a fret saw and cut every piece by hand or i can use a power tool and cut the parts with my 10 inch table top bandsaw OR create the laser cutting file and cut the parts with a laser. I did not push the start button on the laser machine the guy who operates the laser did that. Now we are splitting hairs of exactly who did what.

Is the prototype model of a kit run considered a scratch built model or a kit?

 

[Dave Stevens (Lumberyard)]

Is the prototype model of a kit run considered a scratch built model or a kit?

this is not even a prototype it is a designing process for a prototype that can be used for a kit or semi-scratch project or a scratch project

interesting question if a prototype is built "of a kit" then your actually building a kit. If your the designer of the prototype to be used for a kit then the original build is indeed scratch.

if the project is designed for different degrees of building
A buying all the laser parts, 3d printed carvings, milled wood it would be considered a "kit"
B if you just buy the laser parts and 3d printed parts or one or the other it is semi-scratch
C if you start with nothing but the drawings then it is a scratch built project.

 

[Dave Stevens (Lumberyard)]

what i found out is super glue sticks to the char but not as well if you remove the char. I can snap apart a joint if the char is not cleaned but it is difficult to snap apart a joint that has been cleaned.

what i did was to take the joining surfaces and clean them up a bit by using a block with sandpaper.



i didn't have to remove all the char just a little cleanup

 

[Dave Stevens (Lumberyard)]

assembly of the double frames i used a print of the frames. The print is sitting on a sheet of metal and the parts are placed over the print of the frame.



i am using rare earth magnets to hold the parts in place. These are extremely strong, and they hold the parts down.



Once both parts of the double frames are glued up i switched glue and used wood glue to join the two halves together.



You do not have to use the magnet method you can also use pins along the pattern or if your using super glue to join the pieces then you don't need anything to hold the pieces in place. Just hold the two pieces for 15 seconds and the glue will grab.

 

[Dave Stevens (Lumberyard)]

Between the double frames (bends) are single frames (filler frames) on Hahn's original model he also built the filler frames as doubles. He did this because his model is built to 1/8 scale and the single frames would be very delicate and tend to distort if built as singles. I upped the scale to 3/16 so i built the filler frames as singles.
when i broke down the frames they are joined with a scarf rather than a butt like the double frames. Each scarf fits only the end of a futtock, you cannot mix up the pieces because they will not fit right.



after making a couple frames i realized i did not have to build them on the pattern like i did with the double frames. The laser cutting is so accurate when I pinched the scarfs together and the frame fell into the right shape. One thing i did notice is when i sanded the face of the scarfs and i was not at an exact 90 degrees the frame pieces did not lay flat. It does not take much to affect how the frames will lay flat. to begin with the laser does not cut on an exact 90 drgree angle. The laser beam spreads out resulting in an ever so slight angle.
What i did to ensure the frames went together flat i assembled them along the edge of a piece of glass. The red clamp pinched the scarf together while the black and pink clamps held the pieces flat.



each frame was assembled in sections



Then the sections were joined to form a finished frame.



the job of building the frames went quite well



An alternative to building the frames from laser cut parts would be the way Harold did it and that is to first build a frame blank, glue the frame pattern to the blank and cut out the frame. The frames are so close together the joinery of the frames will not be seen in the final model, so with that in mind you can skip building up the frames and cut them out of one piece.

 

[Dave Stevens (Lumberyard)]

all the frames have been built so the next item to design is the deadwood which is a simple structure. The parts are laid on a flat surface and clamped together



there are two parts to the deadwood the first is made-up of the keel, stern post and inner post. These parts are wider than the deadwood



i did the deadwood different than Hahn's plans the rising line he used was a arc what i did was add steps for each frame which created a ledge for the frames to sit on.

 

[Dave Stevens (Lumberyard)]

getting back to the frames as you can see on Hahn's drawings each frame is at an angle to the deadwood and that angle changes with each frame.




The angle is critical, and it has to be just right so i am using a 4 inch disk sander. I guess you can sand the angles by hand but that would be a bit difficult.




what i did was make up a cardboard pattern and starting with the Z frame i set the angle



As i did each frame i cut off the last frame from the template and reset the table

 

[Dave Stevens (Lumberyard)]

Cutting that angle at the foot of the frame is critical and it has to be even and at the correct angle. Here is my method by using the laser char as a guide. If you are not using laser parts, then take a pencil and darked the surface.

first contact is very light just to get the angle of the face to the disk, making sue your even across the face



look at your piece and sand a little more keeping the char level



opps slightly to much at the right side i am losing the level



ok good a slight adjustment and it is back to level



and the final angle



remember there is a right and left frame so make sure you flip the frame for the other side of the hull. There is no fixing the angle if you cut it wrong you will need to make another frame. you got to do this 28 times.

 

[Dave Stevens (Lumberyard)]

Now comes the setup what i am building is the stern first starting with frame Z and the rest of the frames will be built off frame Z
Looking at a 3D model you can see the steps for the frames to sit on.
Building the stern in 3D modeling is quite different than actually doing it so let's see how it goes.



here are different views of the deadwood, frame Z the fashion timber sitting against frame z and the transoms.

 

[Dave Stevens (Lumberyard)]

this project is working with blanks that have to be sanded and shaped, so which type of sandpaper to use, there are 2 to choose from

Silicon carbide is a sharper and harder grain compared to aluminum oxide, but silicon carbide is less durable because it is brittle and has a more narrow shape that wears down at an increased rate. Due to its razor-sharp grains, silicon carbide will have no problem easily cutting

aluminum oxide is the most frequently used grain in the industry because it does a pristine job on a number of materials including bare wood, painted surfaces, and metal. Additionally, aluminum oxide is exceedingly durable.

i use Silicon carbide disks, belts and sheets but one issue it is very sharp and cuts real fast even your knuckles, all it takes is a lightest contact and before you can react it will cut deep. It is brittle but sanding wood it will stay sharp for a long time.

 

[Dave Stevens (Lumberyard)]

sanding the angle on the foot of frame Z is critical and has to be exactly right. If this angle is off everything else will be wrong because from this point on i am building off of frame Z

 

[Dave Stevens (Lumberyard)]

Once frame z is in place the only thing holding it is the surface between the angle on the foot to the deadwood. It would be easy to snap off the frames so to beef up the structure at this point is to add the transoms. There are no patterns for the transoms on Hahn's original drawings so this is one of those times all you can do is makeup a rough blank and fuss with it until you have a reasonable fit, then once everything is in place the final shaping is when you sand the hull. There is a lower cone shaped piece right at the bottom where the foot of the frame meets the deadwood., that piece i will add later on.



before adding the wing transom at the top notches are cut in for the stern timbers



and it is added to the stern

 

[Dave Stevens (Lumberyard)]

The set up started with digitizing and laser cutting the jig from the original Hahn drawings. Frame Z is now secure and strong enough to build off. Frame Z was glued and pinned to the deadwood. Next i took frame W and using clamps i held it in place. Then the structure was set into the jig, not glued in the jig just set in the notches. The frames are slightly wider than the notches, so it was a snug fit,

 

[shota70]

Dear Dave, great project! I will continue to follow with great curiosity

 

[Kurt Konrath]

this project is working with blanks that have to be sanded and shaped, so which type of sandpaper to use, there are 2 to choose from

Silicon carbide is a sharper and harder grain compared to aluminum oxide, but silicon carbide is less durable because it is brittle and has a more narrow shape that wears down at an increased rate. Due to its razor-sharp grains, silicon carbide will have no problem easily cutting

aluminum oxide is the most frequently used grain in the industry because it does a pristine job on a number of materials including bare wood, painted surfaces, and metal. Additionally, aluminum oxide is exceedingly durable.

i use Silicon carbide disks, belts and sheets but one issue it is very sharp and cuts real fast even your knuckles, all it takes is a lightest contact and before you can react it will cut deep. It is brittle but sanding wood it will stay sharp for a long time.

View attachment 452832

this project is working with blanks that have to be sanded and shaped, so which type of sandpaper to use, there are 2 to choose from

Silicon carbide is a sharper and harder grain compared to aluminum oxide, but silicon carbide is less durable because it is brittle and has a more narrow shape that wears down at an increased rate. Due to its razor-sharp grains, silicon carbide will have no problem easily cutting

aluminum oxide is the most frequently used grain in the industry because it does a pristine job on a number of materials including bare wood, painted surfaces, and metal. Additionally, aluminum oxide is exceedingly durable.

i use Silicon carbide disks, belts and sheets but one issue it is very sharp and cuts real fast even your knuckles, all it takes is a lightest contact and before you can react it will cut deep. It is brittle but sanding wood it will stay sharp for a long time.

View attachment 452832

Been there done that! And you know when you sand the finger it is time to stop on that piece!

 

[Sgt_Bill]

Hello Dave, I have a question about the stepping of the frames to the deadwood. I'm sure that the stepping is more practicle in reality than the Hahn smooth bearding line. So the question: did you follow the Hahn lines? If yes, did you use the point of contact at the fore or aft end of the frame?
I intend to build the Warrior and will be using your thread to model the deadwood to frame look.
Thanks, Bill