Lighthouse

[reible]

I believe those are being cut with Bird's-Mouth Joinery Bits or sometimes called multi-sided glue joint bits. I could look them up for you but since I'm just in on a short break I'll let you guys do that or when I'm back in for lunch I'd do it.

I might have mentioned sets as they sometime do come that way, one bit for 6 or 12 sides one for 8 and one for 16 sides. There maybe more out there but that is what I'm remembering, with my mind that might be a little short on what is currently on the market.

The joints shown are of course compound cuts and you need to do the figuring or consult the instructions for that information.

Ed

[BuckeyeDennis]

Bit SETS?

What am I ignorant of?

The pix appears to show a simple 90 degree v groove cut into one edge of each segment.

Is the compound angle a factor?


I think the devil is in the details which I seem to have have missed entirely.

I asked myself the same question. But the answer has to be "no". The inside angle has to fit the 90-degree outside angle on the mating part, and thus it must be a 90-degree inside angle.

ExtraMile, I think the main problem is that you are centering the inside angle on the edge of the workpiece. But to get the outside edges of the workpieces to line up, you have offset the cut toward the inside of the cylinder. The illustration below shows what I mean.

Birdsmouth joint.PNG (7.25 KiB) Viewed 8910 times

Also, it looks like some of the workpiece edges have not been jointed. If you want a tight fit, getting those edges nice and straight would help a lot.

[reible]

Some bug bit me on the lip so I'm back in while I deal with that.

Since the windmill has a taper to it then the joints become compound. If there were no taper then there would be no compound cuts needed. The compound cut occurs in the stock before the routing is done.

The bit set I have came from MLCS. The current price is about $70 if you want the 3 bit set or about $30 for each bit on sale at this point.

Scroll down the page to see the item.

http://www.mlcswoodworking.com/shopsite ... light=8357

If you have the catalog C-125 look on page 27.

Ed

[BuckeyeDennis]

Some bug bit me on the lip so I'm back in while I deal with that.

Since the windmill has a taper to it then the joints become compound. If there were no taper then there would be no compound cuts needed. The compound cut occurs in the stock before the routing is done.

The bit set I have came from MLCS. The current price is about $70 if you want the 3 bit set or about $30 for each bit on sale at this point.

Scroll down the page to see the item.

http://www.mlcswoodworking.com/shopsite ... light=8357

If you have the catalog C-125 look on page 27.

Ed

I guess it depends on how you define "compound". I agree that the inside birdsmouth angle is compound relative to the centerline of the tapered workpiece. But it's a straight cut relative to the edge that it's on, which presumably guides against a fence when cutting. The "tilt" of the 90-degree inside angle will indeed need to change with the taper, though.

I've never tried it, but why couldn't you make that cut with a dado stack and a tilted table? Or a molding head with Vee-groove knives, for that matter? It seems to me that the special router bits are needed only because you can't tilt the router or the table on a conventional router table.

[algale]

These are easily done on the table saw with a regular blade, even when the board is tapered. Blade it set to the angle for the number of sides, the board is run through one on edge and then run though on its face.

This article explains it all and provides useful calculators.

http://www.duckworksmagazine.com/04/s/a ... irdsmouth/

If you are concerned about reducing the amount of work need to round it in to shape, there's a formula given on this page:

http://ngc704.home.comcast.net/~ngc704/ ... 0page%202/

[reible]

Perhaps we are getting a little off topic but just to complete the thought process for those following this.

I have no idea what the taper is on the windmill but just to make it interesting let say it is 4 degrees. Each part has to be cut such that it tapers, in this case 2 degrees on each side. The top and the bottom also have to be cut to match the angle of the side or 4 degrees. If you add a top/bottom to the inside then it will also have to match the angle to fit.

With the pieces cut (they are called staves btw) you then run one edge against the router bit with fence and it cuts the bird's mouth. In most case you will run this in stages cutting deeper each time by moving the fence with the final cut being lighter. You need to leave a small edge on the side where it touches the fence to maintain that edge. The location of the bit vertically needs to be controlled on set up and once set correctly it need not be adjusted for the remainder project.

The router bits are intended to make this process easy. Could they be done other ways, sure why not. Cutting them with a router bit will give you nice clean surfaces, a saw blade not so much...... For me it just seems like a router is made for this sort of thing.

I have a router holder table insert that allows the router to be tilted and I use that to make siding and roof parts for birdhouses. I guess I could use that with a straight spiral bit to do this too.

Anyway I've got to get back at it.

Ed

[ExtraMile]

360/8 = 45
45/2 = 22.5
So each angled cut of the birds mouth is 22.5 am I correct?

[JPG]

360/8 = 45
45/2 = 22.5
So each angled cut of the birds mouth is 22.5 am I correct?

Methinks 45 would make 8 sides.

Halving the angle would result in 16 sides(IIUC).

[ExtraMile]

Edit: these cylinders are now, lighthouses

All done cept for figuring out a light source. I think I will use a solar powered LED walkway light! And yes, I decided to bore a 1.5 inch hole, 7 inches above the floor, for Eastern Bluebirds.

Additionally, these received a dry brush treatment of white/red and a light sky blue, to give them a patina.

[eartigas]

What did you use on top of the lighthouse? Looks like something plastic but is it something sold for this type of project?
Thanks