Compound joints for rocker frame

[Anonymous]

Hi all,

I've decided to try to finish a project that her indoors asked me to start a couple of years back, a carved rocking horse. We bought a kit and while the carving is mainly a matter of patience, the rocker assembly (which I thought would be the easy bit) has had me scratching my head.

The rockers are connected to a 4 piece frame, this has 2 curved pieces that have a 10 degree bevel on the top and bottom, this allows the rockers to toe in at the top. These curved bits are connected at each end to pieces that have a 10 degree mitre at each end.

The problem I'm having is that no matter how careful I am the 4 pieces won't join up with square joints. It looks like I need some kind of bevel on the ends of the curved bits.

The plans and instructions don't mention this at all, question is, am I missing something obvious or am I just no good with a saw?

Hope someone can help with this.

cheers
Mitch

 

[Chris Knight]

Mitch,

It sounds a bit reminiscent of rocking chairs I made. I may be able to help but it would be preferable if you can you post a picture or a sketch.

 

[Anonymous]

Not posted a pic before, hope this works!

This is the frame that the actual rockers are connected to, so I assumed I should pay attention to getting good joints here.

When viewed from above the end pieces look as if they had a natural tendency to toe in slightly, but that implies the side pieces are not straight/flat, which they are (I think).

cheers
Mitch

 

[Chris Knight]

Mitch,

No they are nothing like my chair - however the answer to your question is yes, I think you are missing something obvious!

The ends of the curved pieces need to be cut at a compound angle! You can visualise this if you imagine rotating the curved pieces about their long axis, until the two pieces are 90 degrees to the vertical (ie the curves are in a horizontal plane and a mirror image to one another). It is plainly impossible to marry the ends with a flat surface - which you can only do when the two curved pieces are side by side in the same plane and orientated the same way.

What you need to calculate is a "hopper" joint angle. So-called because wooden hoppers (like squarish funnels) need to be cut at a compound angle. I will try to find a suitable calculator but there are several on the web.

 

[Anonymous]

Thanks Chris,

When I increase the angle that that they oppose each other it becomes obvious, the 10 degree angle was just too subtle for me to realise what was happening.

I haven't found much on hopper angles so far on the net so if you have anything to hand it would be much appreciated.

cheers
Mitch