Advice Please: Best Way to Cut Archs & Curves?

[NinjaEpisode]

So I'm pouring over the Pac Cab Plans on Jakobud's site and I have a question.

The Cab shows an R55" on the front inward curve and on the top arch.  What exactly does that mean? I'm guessing the "R" stands for Radius, and the arch/curve represents the outside edge of a 55" radius circle?

If so, ok, so I can create the arch using a make shift protractor of string and a pencil secured to a center point.  Where do I place the center point?

Best way to cut it?  Just use a jigsaw?

p.s. Tried searching didn't find anything.

[bdsjake]

that's would I did for my pac cab.  the center point may be off the the cab or at least down near the bottom.  its trial and error to find it, but you have two known points in your curve, where you start and end at the front and back of the side piece (the upper left and upper right corners).  so move your center point around until it fits -- you will want a helper for this.

jig saw is about the only thing to use.  after I cut the side pieces I clamped them together and used a power sander to smooth out the curve.

[whammoed]

May be more trouble than its worth but you could make a circle cutting jig for a router:
http://www.woodworkingtips.com/etips/etip102000sn.html
No need for sanding afterwards.

[Darkstalker]

"The Cab shows an R55" on the front inward curve and on the top arch.  What exactly does that mean? I'm guessing the "R" stands for Radius, and the arch/curve represents the outside edge of a 55" radius circle?"

Yup, you got it.

"If so, ok, so I can create the arch using a make shift protractor of string and a pencil secured to a center point.  Where do I place the center point?"

Actually, you'd be making a drawing compass.  Protractors are the things you use to measure and mark angles

Here's what you do once you have a compass set to 55 inches:

Set the anchor at the top of the side panel where the edge of the R55" arc is, and mark an arch at the bottom of the cabinet.  Do the same thing with the other "corner" of the arc.  Place the anchor where the two marks you made cross, and draw the arc between the two original anchor points.  Not quite sure how you would make the R40" or the other R55" since your center would be floating in space.  Best bet would be to make a template or something with the arc top arch and copy it to the front side.

"Best way to cut it?  Just use a jigsaw?"

A jig or bandsaw would be the best way to go.  If you don't trust your saw skills, get it close and sand it the rest of the way...You need a jig to use a router like this, so you'd have to make a jig with a band or jigsaw anyways.  (Fish...cut bait...fish...cut bait)  Once you finished a side, you could probably use a router to cut the other side using the first side as your jig, so to speak.  You'd have to have a pretty long bit though, depending on how thick the side panels are.

[Nannuu]

Set the anchor at the top of the side panel where the edge of the R55" arc is, and mark an arch at the bottom of the cabinet.  Do the same thing with the other "corner" of the arc.  Place the anchor where the two marks you made cross, and draw the arc between the two original anchor points.  Not quite sure how you would make the R40" or the other R55" since your center would be floating in space.  Best bet would be to make a template or something with the arc top arch and copy it to the front side.

To make the others just place the panel on the floor of the garage and mark the centerpoints on the floor or piece of wood set out there.  Have someone hold the string or stick a nail in the piece of wood.

[Darkstalker]

"Whew, someone passed geometry."

Yea, it's one of those rare moments that I actually need the information I got in that class...heh

"To make the others just place the panel on the floor of the garage and mark the centerpoints on the floor or piece of wood set out there.  Have someone hold the string or stick a nail in the piece of wood."

Good idea, I didn't think about that.  I'd suggest using another piece of wood instead of the floor though, just to make sure you can keep the string tight.

[Nannuu]

You are quick, I'd taken the school comment off so I wouldn't offend.  Ah well.

[Darkstalker]

Eh, no offense taken.  I'm a geek which is a title I readily accept  

[Jakobud]

Regarding my plans, I do offer all of my plans to some sort of scale, so if you were creative enough, you could take it into photoshop or something and scale it up and have it professionally printed out at the actual size of the cabinet and then use that as a template for cutting.  That is the only reason I have all my plans at a real scale you can read, so that you know how big you need to scale the image to get an actual size picture.

Regarding the actual 'cutting' of the wood in an arc, i'd recommend that you get close with a jigsaw then take a power sander to the rest of it to smooth out the arc.

[NinjaEpisode]

Thanks all.

Unfortunately Jakobud, I'm actually scaling down the measurements for use in a miniturized version of the cabs.

Since the wife isn't real keen on having a bunch of full sized arcade machines in the basement, my intent is to scale them down by approximately 70% thus my questioning regarding the arch measurement.  I wanted to make sure I understood exactly what it meant.

The first cab will be a dedicated Pacman cab, and hopefully, with any luck, once the wife sees the finished product, she'll be willing to let me build more.

My hope is the "miniturized" versions will be less overbearing and she'll let me make several.