For a typical cap construction with no sidewalls or tip spacers, what's the offset of the core template to the base template? Is it 2mm?

Reason I ask is, wouldn't it be easier to cut the core template first and shape your core; then add a 2mm thick strip of plastic (maybe lexan or strips of base material) to the outside of your core template, and then route the base material after?

I've had a really tough time printing and cutting separate core and base material templates, and then cutting each so that the offset is consistent all the way around (especially when you piece the paper printouts together with separate sheets). With the method above, you'd be guaranteed the same offset and wouldn't need to cut two templates. And all you'd need is a good flexible plastic strip that's as thick as the offset of your core and base templates.

Is this feasible? Thanks

Mgnovotny,

Typically I try to offset the core 2.5 to 3mm.

I get your idea and think it could work if you had a good method of sticking the plastic to the core template but I'm having trouble coming up with what that method would be. You'd want to be able to take it off and put it back on at will but you'd also need the attachment method to not distort your shape or get in the way of your routing.

An alternative approach I've had success with is to start with a base shape I like and then make a smaller version of it by offsetting the bearing roller guide on the trim router. Here are the steps (roughly):

1. Make base template
2. Trace and rough cut a second base template
3. Use router to make rough cut template into an exact copy of the good base template.
4. Clamp or screw templates together so they are stacked.
5. Trim the top template inward 2.5 - 3mm using a straight cut bit (w/o a bearing) and the bearing roller guide on your trim router. Be sure the you set the depth of the bit so that it gets all the way through the top template (it's OK if is scars the top of your other template). Also make sure the bearing on the roller guide is running along the the middle of the bottom template.

After the steps above you should have a base template and a core template that is constantly offset all the way around.

That does sound easier. Didn't realize you could offset the bit using a roller bearing guide. Thanks for the tip.

With the method I had talked about I would have actually just used strips of plywood with kerfs along one side for bending around curves. It's 1/8" thick so sounds like it would be the right offset. I have access to a lot of kerfed plywood so I would have just brad nailed it to the edge of the first template and probably discarded it after I was done.

I'm also laying the kerfed plywood across the ribs in my mold as I don't have time to cut that many strips of lath and and can't find it at a hardware store here.

Thanks again for the advice.