PARABOLIC DESIGN #1: Ellipse formed from a Parabola

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Blog entry by BertFlores58 posted 02-23-2011 05:01 AM 3101 reads 1 time favorited 9 comments Add to Favorites Watch
no previous part Part 1 of PARABOLIC DESIGN series Part 2: The hardest part!!! »

A section cut from a conical solid along the vertical axis will give us a parabola. I don’t want to explain much on how it constructed however this parabola can be cut using straight line cuts. On sketch up, it looks like this -

From the looks on the drawing… a lot of planning came up with the following questions as my guide:

1. What wood should I use?

At first, I was about to use a plywood with flats be covered with veneer of two different wood color however, the veneer is not so strong to hold specially if cut into small pieces. The best solution is to laminate two kinds of woods. Here I decided 5 mm for the thickness. After lamination, a total of 10 mm brown and white wood. After thicknessing I have about 8 mm thick (3/8 inch). Probably will be thinner after final sanding and planing.

2. How do I cut the wood? ...

Before cutting, the pattern is directly penciled in the board… It will be possible to paste the pattern but I like to cut a wood with pencil line. I like to see and control the wood tearout during cutting.

The greatest challenge of them all is to cut the pieces… Using Circular saw will allow 2mm kerf and wider using others. Scroll and Band saw are not available. Finally, why not use a Japanese saw and my thinnest hacksaw available (Thanks LJ Philly Edwards had given me this hacksaw for free when I visited him in London.)

Okay, the challenge is on… My skill in freehand sawing is at stake… So I had to sharpen the hacksaw which is 17 tpi with a triangular file.. No kerf bending on the saw teeth… A combination style of rip and crosscut.. After testing the saw… I was satisfied… A little bit tight but I feel okay. It cuts also straight… TIP: IF YOU ARE NOT SATISFIED WITH YOUR SAW… DO NOT USE IN PRECISION CUTTING LIKE DOVETAIL.

CORNERS FIRST… Cut the 4 corners….. Actually 7 passes of cuts for every corner. Set them in groups.

ELLIPSE NEXT … started in the shortest cut using first the Japanese saw then backsaw. Set in groups. There are some errors during cutting but managable to be used. So far I was lucky only one breaks when I accidentally tap my Japanese saw sideways…. The wood glue manage to join them together. Another error is when I mistook the guide line which is the wrong as I have to flip it first before making the cut.

No pictures taken during the cut on the ellipse portion.

3. How do I glue it? ... using masking tape.. two pieces at one time. Waking up early, the pieces are glued together and taped. This is before I go to my office work. In the evening, I check the glue if dry and apply more glue. If it warrants, the adjoining pieces will be joined. Here is how it looks ….

notice the tape that holds the pieces together. The only challenge in gluing is to hold it firmly in place. My priority is to have lesser gaps than being offset from the design. The strength of the glue is found when the wood are close together. It is not wise to fill in the gap with a glue.

I hope you enjoy reading this…. I always welcome critics and suggestions.

-- Bert

9 comments so far

View Dave's profile


11429 posts in 2868 days

#1 posted 02-23-2011 05:59 AM

I envy your ability. My eyes wouldn’t even let me try to do what your doing.

-- Superdav "No matter where you go - there you are."

View degoose's profile


7234 posts in 3383 days

#2 posted 02-23-2011 10:19 AM

I like this…

-- Don't drink and use power tools @

View Sheila Landry (scrollgirl)'s profile

Sheila Landry (scrollgirl)

9231 posts in 2948 days

#3 posted 02-23-2011 03:33 PM

Wow, Bert! This is going to be one beautiful design! I am fascinated watching this. Can’t wait to see what is next!


-- Designer/Artist/Teacher. Owner of Sheila Landry Designs ( Scroll saw, wood working and painting patterns and surfaces. "Knowledge is Power"

View Cozmo35's profile


2200 posts in 3064 days

#4 posted 02-23-2011 04:04 PM

Bert, You have got skill and talent my friend!

-- If you don't work, you don't eat!.....Garland, TX

View BritBoxmaker's profile


4611 posts in 3065 days

#5 posted 02-23-2011 04:38 PM

Well done, Bert. As you’re laminating anyway I probably would have gone the veneer route, knife work being easier and not incurring a kerf gap to deal with. I admire your courage and application here. I am also a great supporter of the use of masking tape as a clamp in this sort of glue-up.

-- Martyn -- Boxologist, Pattern Juggler and Candyman of the visually challenging.

View shipwright's profile


7996 posts in 2826 days

#6 posted 02-23-2011 04:53 PM

Super job Bert on both a physical and an intellectual levels. I
ll be following this one. ....and by the way add me to the list of masking tape users for glue-ups.

Great work.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees.

View BertFlores58's profile


1698 posts in 2950 days

#7 posted 02-24-2011 01:33 AM

Thanks to all of you buddies. You know one thing in doing things that make the work easier are encouraging words towards your endeavour (english spelling hah)... Challenges comes later and though you have plans ahead, direction changes due to what you encounter. Along the way, realities never stops for us to accept a twist.

Just yesterday night, I just look at the two halves of elliptical parts already glued, I realized that I have to make one more exactly the same I had made… plus the sides (two blocks longer side x 2 plus the short side)
The reason behind it, I could not join the two halves to create alternate color of the wood even you flip it the same pattern will come out. The diagonal corners’ pieces have to be joined alternately to produce the right pattern…. If I will be successfull, I am making a complete all sides parquetry for the box…. The botom and top lid plus the sides…

Let’s hope for the best… ONE is ENOUGH, TWO is TOO MUCH, but THREE is NEVERMIND. Grammar is wrong but the thought is correct. lol

-- Bert

View GaryK's profile


10262 posts in 4017 days

#8 posted 02-24-2011 01:39 AM

Very cool!

That is a great idea. (sorry, but I might have to steal, oops, I mean use it on some project of my own)

Ipagpatuloy ang magandang gawain….

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View BertFlores58's profile


1698 posts in 2950 days

#9 posted 02-24-2011 02:15 AM

Okay lang Gary… I am sharing all to everyone… Actually, I have stolen some of your techniques in joinery and parquetry in some of my unposted projects. I’m glad ang galing mo na magtagalog. Salamat. God Bless to the family.

-- Bert

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