My knees are killing me

[JimM]

Recently, while waiting for paint to dry and other down times, I have been working on knees for the Constitution. I am terrible at it. I started by edge-gluing 5mm planks and then shaping them to the ¾” size that I’ll need (the ship needs 62 knees.)
I have completed four that seem to be acceptable. I’ve thrown away about a dozen.
Can anyone recommend a process that will produce consistent results?
The leftmost knee is made from planks. Number two is from a wider panel of basswood. The third is cut from a wooden ruler. The last is a prototype from fake wood from cove molding that I got at Lowe’s.


So does anyone have any suggestions, tips, advice? My goal is a consistent size.

Jim

PS The longer arm is thicker so I can bevel it to fit the bulwark

 

[Short John Bronze]

Compromise! Shape a length of wood to the profile of the coving (or more specifically, your knees) and cut slices from it. The grain direction will be wrong (and weak) but I guess that on a model they are not load bearing.

 

[JimM]

Great idea John

 

[Jim Fortnam]

Your experience is mirroring life.

Knees were cut from curved timbers for strength. Trees in the woodland would be marked up for specific parts, with ‘grown knees’ particularly prized. Then iron knees became a thing, because suitable timbers were no longer to be found.

So, you find that grain orientation is allowing splitting. Let’s go to first principles.

What wood are you using? Fine grain is essential, so box, fruitwood like apple or pear, lime is good of course.

Then what are you doing to apply more pressure than the tensile strength of the wood? Too much handling, or is it breaking when you start cutting the curve?
Sharp tools, if you are cutting. I mean really sharp, scalpel sharp. Fresh scalpel blade sharp.
And a good vice. Or holding method, like tape or hot glue

Or perhaps the real answer is gang cutting. Make up a pair of profiles from metal, and use them to cut the curved profile on the edge of a 6inch block of timber, or end of a suitable plank. You have a huge handle, so you can focus on using a moulding plane or file, or even a roughing cut with a small router. When you have the right curve all along the 6 or 8 inches, then saw out the straight sides to make a run of knee, then slice that profile into individuals.

Yep - take fresh look at the problem, always helps.

Jim

 

[JimM]

Good idea Jim.
I’m going to try that on a length of fake wood. It’s from Lowe’s and it’s made of plastic (I think) which will minimize the grain issue

Jim

 

[dockattner]

Hi Jim,

Shortcuts work for the center section of the hull...but as you approach the bow and stern the angle changes. I simply make patterns from cardstock - trace that on to a panel of appropriate thickness - and cut the knees out individually. Enjoy the process!

 

[DARIVS ARCHITECTVS]

I cut and shaped all my knees from coving. As Short John Bronze said, the grain direction is wrong, and the knees will occasionally break if roughly handled. However, this shortcut lets you cut the basic shapes out fast. Because the angle of the hull changes from fore to midships to aft, ALL your knees need to be custom fit as far as angle goes. They are rarely 90 degrees, and vary from approximately 85-95 degrees. If you are is a hurry, you won't make a very detailed model, and the work will get sloppy and unattractive, so take your time shaping knees in pairs or groups of four, varying angle and leg length as necessary. The more you make, the faster YOU get!

After you make one custom fit knee, trace it out to use as a start for making the adjacent knee, leaving extra wood at the deck and bulwark edges to allow you to adjust the angle. Test fit by holding the new part in the hull using angled tweezers. Use a large sanding block to shape the edges that contact the hull and deck. Adjust the length of the legs, round the corner over at the top leg. Hand sand the knee, add bolt head marks with a pencil, and stain as desired before gluing a pair of knees in place, port and starboard. Sit back and admire your work, then do it again.



Custom dagger knee made from two pieces.



The results are worth the effort!

 

[AllanKP69]

Shortcuts work for the center section of the hull...but as you approach the bow and stern the angle changes.

Great point! While the dead flat has virtually no variation in shapes, the angles change as you move forward and aft so one size/shape does not fit all.
Allan

 

[AndyA]

Knees were cut from curved timbers for strength. Trees in the woodland would be marked up for specific parts, with ‘grown knees’ particularly prized.

So, you find that grain orientation is allowing splitting.

What wood are you using? Fine grain is essential, so box, fruitwood like apple or pear, lime is good of course.

All true. The curved timbers that Jim refers to are known as crooks and they are found where the branch of a tree grows from a trunk {see photo below and item A in the drawing). These are strong because the grain curves around. Some (dedicated) modelers make knees that way from small branches. It is tempting to cut out knees as shown in B because you can use the side of your stock as one of the straight sides of the knee. But that makes a weak piece. Item C is stronger but is more work to cut and wastes more wood. Fair winds!

 

[AllanKP69]

If you REALLY want to go for it, if you have an apple orchard near by, ask them if you can pick through the cuttings before they burn them after fall pruning. The joint at the small branches to larger ones is close to the trunk and root configuration. I tried it years ago and it really does work, but it was not worth the time to let them dry for a year then cut them to size. Tight grained wood like true boxwood and castello will hold up against the inherent weakness of the grain being stressed even on these small knees.
Allan

 

[Roger Pellett]

You could also make your own plywood to cut these from by laminating two layers of wood with grain running in two directions.

I have one model that required knees. I cut them from pear wood without worrying much about grain orientation. Pear is plenty strong for this application. Kit supplied woods like basswood are not.

Home improvement stores now often stock select hardwood species. For example our local Menards sells maple. This could also be a choice.

Roger

 

[tigerdvr]

Recently, while waiting for paint to dry and other down times, I have been working on knees for the Constitution. I am terrible at it. I started by edge-gluing 5mm planks and then shaping them to the ¾” size that I’ll need (the ship needs 62 knees.)
I have completed four that seem to be acceptable. I’ve thrown away about a dozen.
Can anyone recommend a process that will produce consistent results?
The leftmost knee is made from planks. Number two is from a wider panel of basswood. The third is cut from a wooden ruler. The last is a prototype from fake wood from cove molding that I got at Lowe’s.

View attachment 539756
So does anyone have any suggestions, tips, advice? My goal is a consistent size.

Jim

PS The longer arm is thicker so I can bevel it to fit the bulwark

Funny but not really funny--I saw your post about your knees killing you. I immediately had to open your post because MY KNEES ARE KILLING ME. My real knees (the ones that are part of the legs!) Aspercreme will help my knees but I don't think it will solve your problem.
Good luck with your project.

 

[Stuart Little]

Funny but not really funny--I saw your post about your knees killing you. I immediately had to open your post because MY KNEES ARE KILLING ME. My real knees (the ones that are part of the legs!) Aspercreme will help my knees but I don't think it will solve your problem.
Good luck with your project.

My thoughts too!

 

[OlivierF]

Similar to @tigerdvr and @Stuart Little, when I read the title to your post and saw the first pictures, I assumed you had sore knees from crawling on the floor looking for pieces that fell off the bench! This I know from personal experience!

 

[Norgale]

I cut and shaped all my knees from coving. As Short John Bronze said, the grain direction is wrong, and the knees will occasionally break if roughly handled. However, this shortcut lets you cut the basic shapes out fast. Because the angle of the hull changes from fore to midships to aft, ALL your knees need to be custom fit as far as angle goes. They are rarely 90 degrees, and vary from approximately 85-95 degrees. If you are is a hurry, you won't make a very detailed model, and the work will get sloppy and unattractive, so take your time shaping knees in pairs or groups of four, varying angle and leg length as necessary. The more you make, the faster YOU get!

After you make one custom fit knee, trace it out to use as a start for making the adjacent knee, leaving extra wood at the deck and bulwark edges to allow you to adjust the angle. Test fit by holding the new part in the hull using angled tweezers. Use a large sanding block to shape the edges that contact the hull and deck. Adjust the length of the legs, round the corner over at the top leg. Hand sand the knee, add bolt head marks with a pencil, and stain as desired before gluing a pair of knees in place, port and starboard. Sit back and admire your work, then do it again.
View attachment 539850

View attachment 539851
Custom dagger knee made from two pieces.View attachment 539849

View attachment 539852

The results are worth the effort!View attachment 539853

Shouldn't the knees go UNDER the cross beams? Otherwise what are they holding up?

 

[DARIVS ARCHITECTVS]

Shouldn't the knees go UNDER the cross beams? Otherwise what are they holding up?

Not all knees support beams from underneath. In areas were overhead knees may interfere with guns and other parts of the vessel, lodging knees are attached to the beam from above.

 

[Norgale]

Guess I haven't ever seen that before. But I know what you mean with the knees. I made a couple hundred of them and developed a system for them that worked well for me. I drew the knees at one inch on the two sides that form the 90` angle and then the web across the throat. I cut them all out the same size from 1/4" basswood sheet and then fitted each one where it was to be installed. Mostly no two were alike. By the use of my drum sander and my belt sander with the vertical wheel on it I sanded them all individually to fit. It was a boring job to say the least and there are still 75 or 80 more to go on the top deck. However they really do provide a lot of support and strength to the model and they look good too. Too bad somebody couldn't make them in advance to buy. Your work looks great. You'll have a very nice model when you are through. Norgale