Introduction: Laminated Plywood DNA Model
A few years back I got the idea to build a DNA Helix from wood. Combining my interests of science and woodworking into one! I never intended to write an Instructable on this project so apologies if this one isn't up to scratch. (This is also my first Instructable!).
After a bit of messing around and research I finally found a good way to create the beautiful double helix of DNA. By taking a board of wood and cutting it into thin strips (Laminates), you can create your own type of Plywood that you can bend into amazing shapes impossible with normal wooden boards!
This concept (Bent Lamination) was new to me at the time but it greatly expands what you can do with wood. From some very fancy curvy furniture to a simple wooden drawer handle! It's a great concept to be aware of if you ever need to bend wood in a difficult or unusual way.
And I'm going to show you how!
The materials I used for this project were as follows:
- 14 laminates (2.5x14x1300mm) (Wood Type: Red Deal)
- 6mm dowel (length: 2.4m) (Wood Type: Ayous)
- Base board (300x240x22mm) (Wood Type: Lime live edge)
- Wood glue
- Carpet roll tube
You don't need to use the same types of wood I used, I included the wood species for reference.
If you have a table saw (recommended) or bandsaw, you can use that to cut the laminates. The more uniform the laminates the better as you want the wood to flex evenly along the bend.
The rest of the tools used in this project were basic enough tools (Coping Saw, Hand Drill, Chisels, Clamps). You don't need to use the same tools I did, I just used the tools I had available to me at the time!
Step 1: List of Tasks to Be Completed
Not really a step but a brief overview of what needs to be done!
- Gather required materials and tools
- Soak the laminates in water and form them into shape
- Cut the spirals (helices) to size
- Stain half of the dowels and one spiral (one helix)
- Drill holes for the dowels
- Put in the dowels
- Make the base
- Sand it down then cover the whole piece in clear varnish
- Put the spirals on the base
Step 2: Forming Helices
The two spirals were formed individually beside each other, (instead of as one long spiral and cut in half) to ensure both spirals were the same.
The laminates were soaked in water for a week. This was to increase their flexibility and to avoid them snapping as they're being formed.
One set of seven 2mm laminates were clamped to the end of the carpet roll tube then slowly bent them around the tube without glue. I marked different points along the tube as a guide for the bend. The marks were evenly spaced and measured out. This measurement is for you to decide how tight or loose you want your spirals to be. (Be aware of spring back in the wood spirals when you unclamp, make sure to account for this).
The second set of seven laminates were then clamped beside the first ones so they would be easier and faster to form (and also identical).
They were then left to dry out completely for a week before continuing.
Step 3: Gluing Spirals
After a week had past the laminates were dry and set in place. I numbered each laminate at the end to keep track of their order.
They were then unclamped and each spiral was separated on the bench. Starting with one spiral to avoid mixing the pieces up, glue was applied on one side of each layer and then set back together in the correct order.
When glue was applied between each laminate and they were fit back together, they were placed back on the forming tube and clamped again to set. This part is important. Make sure there's no gaps between the laminates at this stage or you won't be able to fix it once it has set. More clamps are better here.
Step 4: Scraping & Sanding
The next day the glue had set, there was a lot of glue squeeze out. I used a wood scraper tool to remove this excess glue from the edges. This step was hard as it's awkward to hold the wood in a good position while scraping off the glue without damaging the piece. I supported the piece with one hand while scrapping with the other.
Once the excess glue was gone. The spirals were sanded down. This was only a rough sanding to get rid of marks and glue on the wood. The more sanding you do at this point the better though!
Step 5: Cutting the Spirals to Length
I wanted the DNA Strand to have 1.5 turns so I marked one piece at that point. The other spiral was then cut the other to the same length.
I got two 170x170mm pieces of scrap 6mm plywood and cut them into circles to temporary hold the spirals in shape and position for the next steps.
15mm screws were screwed into the ends piece with the plywood on either side. If you're following this, drill pilot holes first to avoid splitting the ends of the spirals like I did!
Step 6: Staining the Piece
I stained this piece to give each part some contrast.
I determined it was best to stain one spiral and stain every second dowel.
The great thing about looking back and reviewing a project is that you can see what you could have done better! I started putting in the dowels when I realized it would be easier to stain the piece first and then put in the dowels to avoid the dowels getting stain on them. Hence unordered pictures above.
I used a dark wood stain and a cloth to apply the stain.
The dowels were cut oversize as they'd be cut to the correct size later.
Step 7: Drilling Holes for Dowels
This step was made easier as the temporary plywood holding the spirals together made it easier to space and drill the holes for the wooden dowels.
I drilled 3mm pilot holes first for the bigger 6mm drill bit.
I had to drill the holes at an angle to ensure the dowels were as level as possible. I measured where I wanted the holes but it's more challenging to drill the holes to match the other side. There is some tolerance as the dowels can bend a little but the more precise you can do this step the better!
Focus on keeping them as level to the horizon as possible. That's the most noticeable!
Step 8: Putting in the Dowels
I cut the dowels roughly to length then twisted them all into place by hand.
The dowels were tight enough for me to use them to alter the shape of the two spirals, so I used them to make little adjustments to the shape of the piece. That's why its useful to cut them a bit oversize.
I cut the ends off the dowels so they were flush with the spirals and sanded the edges down flat with the surface.
Step 9: Making the Base + Carving
The base I got was 300x240x22mm of live edge Lime wood. I chose this wood because I thought it would suit the piece well, as well as being sturdy enough to support the piece.
I used a router to shape either side of the board to give it some more character. I used a 12.8mm diameter Roman Ogee bit for this.
I decided it would look nice if I carved the letters "DNA" into the base. Once marked out and carved, I burned the edges of the letters to make to make them stand out more.
Step 10: Applying a Finish
I chose clear varnish because I like the shine it gives the piece as well as bringing out the grain in the wood.
A layer of clear varnish was applied to the spirals first and then the base. After they had dried, I lightly sanded both and varnished them again.
Step 11: Putting the Spirals on the Base
I applied the layer of varnish to the base before gluing the spirals because then I wouldn't be trying to fit a brush in, around and under the spirals later.
The ends of the spirals were very fragile and were splitting when I tried to screw into them.
I tried to carefully screw them in but in the end I decided it was best to use hot glue to hold them to the base. It wasn’t ideal but it did the job. This did have the added benefit of if the piece got a knock, that the hot glue would fail before the wood and was very easily repaired.
Step 12: Evaluation + Pictures
I like to evaluate my projects. I believe this is a very important step of any project! To see what you've learned and what you could improve on next time.
I've added some of this to the Instructable already as advice but I made a few mistakes when I built it first.
I enjoyed making the project, it wasn’t like anything I have designed or made before. The piece was challenging to build and took a lot of time and thought but I think it met my vision and turned out well in the end. It was difficult to get the dowels level and to put the piece on the base, but I found ways around these problems. One thing I would improve or change; I made the mistake of taking the formed spirals off the tube a day before gluing and they deformed a bit.
And...… We're done! Hope this was helpful to some people. Thanks for reading through it! :)
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