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Maker of Fine Sawdust
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Discussion Starter · #1 ·
Bought a new toy a while back and I'll get to use it soon.

Elliptical Jig



Not really a complete picture of what I need to make. Need to make the whole thing.
Gotta make the casing, key and the jamb. The key is the easy part.



A while ago I made some tracings on some cardboard. One was the opening of the curved
jamb and the other will be a different sized opening.

From the tracing the first thing I made was the template for the 2 1/2" colonial casing


Then I needed to make the template/jig for the curved section of the jamb.

The wall thickness is 5 3/8" so I made 4 template pcs. I put in 1" spacers so the template
will be 6" thick.

Here are the 4 pcs along with the casing template


Here's the spacers being screwed into place


Here's the completed template


For the jamb material I will be using 2 pcs of 1/8" poplar and the Kerfcore that I used
when I made the curved desk. I cut the thickness down to 1/2" so the two pcs of poplar
and the Kerfcore will total 3/4".



Here's a test run to make sure things would work.


Here's the real run. This one is glued up.





Round two coming up.
 

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Maker of Fine Sawdust
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Discussion Starter · #3 ·
You keep your hands off my clamps....:mad:

:laughing:
 

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Discussion Starter · #4 ·
Finished up the first jamb and put the parts into the form for the second jamb.





Then started up on the curved molding portion of the job. I took the pattern that I made earlier and cut it to size so I could use it in the jig. Needs a 6" lead and 6" follow on the pattern so it can register correctly before the molding gets to the cutterhead.

So I removed the cutters I had in the W&H and got set to put the new elliptical jig into position. The hold downs on the bottom of the jig got in the way so I removed one of them and put the jig in place. Found out the screws they supplied with the jig were to short to work with the W&H. It was designed for a Shop Fox, and the table must be thinner. So I went out on a trek to find a 1/4-20 socket head screw. Went to my usual hardware store and they had a 3/4" version. Really wanted the 1". Went back to the shop and tried it out. Got 3 threads to hook up. Not enough for me. So I went to my 2nd choice of hardware stores and they had it in stainless steel.

So I was able to get the elliptical jig on the W&H and after about an hour of fiddling I got everything lined up and I was confident that it was secure and in position.

Drilled holes in the particleboard pattern and used 1" pocket screws to hold the blank I cut out of a 11 1/4" x 30" pc of poplar in place. I used a flush cut bit to pattern the blank to the particleboard.

So now was the first trial run. Put the piece in place and let the machine suck it through. OK, big problem. The inside of the molding got a nice gouge in it. The cutter has a wrap that goes down to far and as the molding makes the curve the cutter hits it and removes stock.

So I take the cutters out of the machine and grind the part that wraps down. I take enough off to stop the problem but keep the radius on the molding.



So now I cut another blank and I ran the molding 1/8" thicker to see what would happen. I was helping it out a bit and over did it and it got a small gouge in the straighter section. But fear not. I lowered the cutter to the proper thickness and ran it again. SUCCESS!!

W&H with elliptical jig


With molding in place


Close up. You can see how the particle board pattern rides on the single bearing
on the right and the double bearing on the left. This is what keeps the blank in the
proper orientation with the cutter.


Here is a pc of 2 1/2" colonial casing that I had in the shop on the right (it's pine) and on the left is the curved casing I just cut.


And here is the curved casing.
 

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Discussion Starter · #5 ·
Made a movie today of the molding being run. I'll try to post it to Youtube sometime tonight and get a link running.

But today I ran 1 more left and 2 more rights of the elliptical molding and then placed them on the jamb to find out if all this work is going to mesh together.

And it did. I figured on a 3/16" reveal, which is what the original one has, and that's what I got. Always a little worried because springback changes the radii depending on how tight the curves are. On mine I have a 3/4" spring, 3/8" for each side, but that was easily pushed back with a few ounces of force and the tight radius didn't change much at all.

Here is the pc, uncut, laid on the jamb.


And after a lot of fanagling and planning and drawing lines here and there I have the two pcs cut and ready to receive the key. Which still needs to be made of course..... These pcs are just laying on the jamb, so the fit is excellent as far as I am concerned.
 

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Discussion Starter · #8 ·
Finished up the parts for both sides of the jamb casings. I glued the loose side together. Tomorrow I'll glue the fixed side casing to the jamb. Last thing to do is to wrap the key with a simple cove and quirk molding.

Filled the hole in with this simple key. It's a copy of the original so the bottom is flush. I'd of had a 1/8" portion below the jamb..


Here's the casing all glued together, I'm using the jamb as a template


And here's the whole jamb/casing. I'm using the clamp at the bottom to hold a small pc of plywood to the jamb. Then I put two shims between the bottom of the casing and that pc of plywood held by the clamp. Push the shims together and it pushes the straight casing tight to the curved casing. There is a #0 biscuit in the joint, the biggest I could put in a 2 1/2" casing.


 

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Maker of fine kindling
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Thats very crafty Leo. You are the man when it comes to such things.

Don't they make some bendable molding for stuff like that?
 

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Discussion Starter · #11 ·
They might. It's a pretty tight radius and it's not a true radius so it would be hard to make it stay. Plus the inside and outside differences in radius are quite a bit. So the compression and stretch on the inside and outside radius are quite different. Not sure if it could do it.

Plus I wanted the elliptical jig. :smile:
 

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Discussion Starter · #12 · (Edited)

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Discussion Starter · #13 ·
Thats very crafty Leo. You are the man when it comes to such things.

Don't they make some bendable molding for stuff like that?
Yes they do.

http://www.flexibletrim.com/G_SearchModel.asp?Model=574

But most of those moldings are designed to curve on the flat. Like going around a curved wall. Not really going around a curved window.

I would suspect if this was true it would be in use all over the place instead of solid wood curved casing.
 

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Discussion Starter · #15 ·
Wow, that's fantastic. How much time you figure you will have into it?
Well, I started it on Thursday and had the jamb in the form for the 1st one completed on Friday. On Monday I put the legs on the curved jamb and started on the milling of the curved casings. By the end of Monday I had the setup completed and working. I had to overcome a few simple problems. By the end of the day I had the left curved molding made. Today I made the other left and 2 right curved moldings. I made the straight sections. I made the keys. I fit and joined all the different sections of moldings for both sides of the casing and I glued what will be the loose casing together.

Tomorrow I'll glue the fixed casing to the jamb and start on the other jamb which is in the form now. It's been dry for over a day now, but I'll leave it in there as long as I can to let the glue cure as much as possible. I need to make the pattern for the casing on this section and run the moldings. After all this "learning", this second one should be a lot easier to make then the first.

So I'll have a total of 5 days for the 2 jambs.
 

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Maker of fine kindling
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Discussion Starter · #17 ·
Stop screwing with me :mad:


:laughing:
 

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I bet Gus could tell his robot to spit that out;)
 

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Discussion Starter · #19 ·
The hardest part would be to get the actual curve into the controller. Unless you have a laser measuring device hooked up to it. Then it's easy.
 

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Maker of fine kindling
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I can make you all the elliptical parts you want. I think what Leo is saying is that he is working from a predetermined shape that may or may not be a true ellipse. If that is the case, it is difficult to program that.
Your molding machine and my cnc would be the way to bang these out so long as we can create our own true ellipse.
Not sure how much time it would save on two openings though. I would start to bury you after the first few.
You did great here. Very impressive.
 
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