Ideas on how to make template

[Jeff Myers]

Please excuse the length of this question but it will take a bit to get
my request worded:

I want to make a jig/template that will allow me to make a 3/4" - 1" thick
flat circular piece comprised of four identicle wedges, i don't want perfect triangles but would like the edges of the wedges;) be arcs that radiate
from the center of the circle out to the edge of the circumference of the circle.
If i drew to intersecting lines that were perpindicular to each other and used a compass to then draw my circle on top of the cross of the two intersecting lines using the intersection as the center of the circle. I could then take the compass and with it being set to same radius of the circle, put the base of compass on the circumference of the circle where one of the lines bisects it and the pencil end of the compass starting at the center of the circle, draw the arc out to the edge of the circe. Do this
three more times using each of the bisect points of the x-y axis lines and
where they cross the circle's circumference,,,that would give me the
four equal wedges i'm looking for with arcs for their sides...on paper.
I want to then make a template/jig so i could then cut these four pieces
out i'm assuming with a router??? so that if i did this with different types
of wood, i could mix/match the wedges back together to make glue up
blanks for cutting boards or for lathe work where each wedge could be a different type of wood. I want the joints to be seamless and want to be able to use this jig/template over and over with different types of wood so i could then have a supply to choose pieces from and they'd all fit
properly with each other.
Any suggestions on how to accomplish this?

I'm thinking using a pin router attachment to do this but unsure how
to make the jig be accurate enough to make the four pieces all identical.
Thanks in advance,
Jeff

[Doug Shepard]

Jeff
Maybe it's just me (too early and not enough coffee yet) but I'm having a real hard time understanding the design you're after. You mention 4 pieces which I interpret to mean you've need 4 quarter circle segments to get to a complete circle, but then you say you want arced sides but yet identically sized so you can mix/match. I'm cant grasp how you'd get a complete circle with only 4 pcs and arced sides unless the sizes differed. Or are you not trying to end up with a full circle piece? You also mention "arcs that radiate from the center of the circle out to the edge of the circumference of the circle" which had me thinking you want concentric rings (like a target) but I don't think that's right either. I've done a fair bit of routing round shapes and may have some ideas if I can grasp what you're trying to do. Any chance you could scribble up a rough sketch and attach it? SketchUp or even paper and pencil then scan it? Or even Microsoft Paint would let you throw something real rough together.

[Keith Outten]

Jeff,

The easiest way is to ask one of our Members who owns either a laser engraver or a CNC router to make the templates. This is an easy task and can be done with precision on either machine. Use the templates that they make to route a working set and put the originals away. If your working templates ever show wear you can make another set from the originals.

Assuming you are going to use a router guide bushing you would need to provide the dimentions of the circle and the guide diameter with router diameter you intend to use. Check the list of Engravers and CNC owners in the Laser/CNC Forum for someone close to you.

.

[Mitchell Andrus]

I make router templates like this on my laser cutter. The design is 'drawn' in Corel, then cut on the laser. Perfect arcs, curves etc. every time. Scaling is a snap and adding an offset is often two or three clicks of the mouse. The trick is.... ya gotta get it into the 'puter first. Simple designs take only a few minutes.

The pattern below took <5 minutes.

If you think this will work for you, post that on the laser/CNC section of the Creek... you'll get help there too.

Mitch

[Jeff Myers]

Here's what i'm trying to accomplish, four segments of a circle, each segment identicle in size/shape to the others, i've shaded two segments
to show how i'll mix/match different color woods to make full cicle platters.
51221

[Lee DeRaud]

What Mitchell said.

Assuming this is what you had in mind,
51223
take the attached .cdr file to whoever does the cutting. It's for a 10" circle, but he can scale it to whatever you want (or whatever will fit his machine).
51224

[Lee DeRaud]

Assuming you are going to use a router guide bushing you would need to provide the dimentions of the circle and the guide diameter with router diameter you intend to use.A guide bushing won't work (unless it's the same diameter as the cutter): the corners will get radiused. Flush-trim bit is the right answer.

The same templates can be used for smaller-diameter circles, you'll just need to cut the outer circle with a bandsaw. You'll probably need to do some cleanup on the outer edge in any case...of course, if you're turning these on the lathe, that takes care of itself.

[Jeff Myers]

Thanks Lee, that is exactly what i'm looking for.
I'm glad you could see through my crazy description,,,i had trouble
describing that setup.
Thanks again!

[Lee DeRaud]

One other note...

This probably works ok with four segments, but I've tried it with 12 and it's nearly impossible not to end up with a small hole in the middle where the points come together. There are ways to adjust for that using straight-sided segments, but not with the arcs.

[Jamie Buxton]

Here's what i'm trying to accomplish, four segments of a circle, each segment identicle in size/shape to the others, i've shaded two segments
to show how i'll mix/match different color woods to make full cicle platters.
51221

You can go to a laser, but it isn't necessary to do that. Arcs of circles are easy. Use a router with a circle-cutting arm on it. That's an arm fastened to the router, with a pivot on the other end.

[Doug Shepard]

Cool. Now I understand what's going on. I'm thinking the same thing as Jamie. Lasering would be ideal but you could do it with a router and trammel arm, although I think this would probably be a case of needing to make a template (or two) to make the template. A Micro-Fence circle jig might be worth putting on your Christmas list. I'm mentally toying with another idea. If I cant get it to make sense, I'll repost.

[Dennis Perry]

Lee, here ya go a 12 seg circle.

Take care Dennis

51225

[Lee DeRaud]

Lee, here ya go a 12 seg circle.

Take care Dennis

51225Generating the Corel file isn't the problem, Dennis, it's cutting it in the wood. As the points get sharper, the fit at the center gets very critical...and wood just won't machine as accurately as metal or plastic (or more to the point, curves in Corel).

[Gary McKown]

Making this template shouldn't be a big deal and certainly doesn't require lasers, CNC, or even a router.

First, if the segments are identical then you only need a one-segment template. Draw the figure to the scale you want (or print the corel file). Paste it on the template substrate, bandsaw out one segment, then sand to the lines. Use it to cut 4 pieces and test the fit. Voila!

[Jeff Myers]

It doesn't seem too complicated and wouldn't need laser'd templates, but
i didn't have Corel so my use of graph paper and compass by hand introduced too much variences to get a perfect fit free hand band sawing
and sanding for that perfect glue line with no gaps anywhere just copying
one segment.
Now that i have Lee's cdr file, i "might" be able to make one segment to use as template for 4 pieces doing it bandsaw/sanding ,,,but i'll get a laser'd template made to rule out as much human error first and then see
how good my copies can turn out when glued up..i'm really going for that
perfect glue joint and having four segments all join perfectly at the center and their corresponding sides is a tough job and with burls and exotics costing as much as they do, i'd like to eliminate as much trial and error testing as possible.

[Ralph Barhorst]

Lee,

"The same templates can be used for smaller-diameter circles, you'll just need to cut the outer circle with a bandsaw."

This is not quite true. The Corel file can be used for other sizes by scaling, but a new template would have to be made in order to keep the radius of the arcs the same as that of the circle.

[Lee DeRaud]

Lee,

"The same templates can be used for smaller-diameter circles, you'll just need to cut the outer circle with a bandsaw."

This is not quite true. The Corel file can be used for other sizes by scaling, but a new template would have to be made in order to keep the radius of the arcs the same as that of the circle.Ah, I see what you're getting at. I only meant that the inner curves still fit regardless of the outer diameter, unlike some other patterns. (There's a term from topology class that I'm thinking of, just can't quite remember back that far.)

I suspect there's a noncircular radial curve you can use that always meets the outer rim at the same angle...but I certainly wouldn't want to try to draw it with Corel.

In any case, within 20% or so, I doubt the difference in curvature would be noticable.