OT - making route jig out of manufactures base plate

[Brewski]

I've got a craftsman router which is ~6" in diameter around the base. conceptually what I'm thinking of doing is drilling holes at distances of for example 1.5" and 3" from the center of the included deck plate to essentially make 3" and 6" circle jigs.

Conceptually I'd think this would work and a drill bit, screw, etc could be left in the baffle for the plate to be pivoted around. I just figured that before I tried it when I got home I'd see if there was something flawed in the thought process.

Take it easy
Jay

[mattk]

Should work, but keep in mind that putting a hole at 3" will result in a bigger than 6" diameter hole. You need to account for the diameter of the router bit.

[davepellegrene]

#8 and #10 finish nails cut to about an 1" long work well for pins using an 1/8" drill bit to drill the holes.

[Soundslike]

What you've described should work fine. It's very much like what a commercially made guide does. But, as previously advised, be sure to account for the bit diameter or you'll end up with a larger hole than you intended. In other words, measure from the opposite side of the bit (relative to the hole you'll be drilling) to locate the point you'll be drilling. Be sure to do a test cut in a piece of scrap before cutting the workpiece so you can make any necessary adjustments. Also, I'd recommend a spiral line leading out from the center to the edge so however many holes you end up drilling in the baseplate will be offset and won't weaken it. You've probably already thought of this, but it's a good idea to use a bit of masking tape to mark on when you're locating the points where you will drill. I like to use a ball point pen because it's more accurate (it consistently marks where you expect it). Finally, if you're flush mounting drivers, cut the outer circle that creates the recess first. That will leave the pivot point intact for use when you cut the inner circle and any irregularities that might result when the cut is completed

[Æ]

Instead of messing up the original base plate, why not just make yourself a throw away base plate form a scrap of wood or whatever. You wouldn't even need to screw it down, something as simple as double sticky tape would hold it in place. Or you could get fancy and make a nicer add on base plate from some plastic or Masonite. When I want to make something, I go to my local plastics store, they have a bin of scraps that they sell real cheap.

[PassingInterest]

I'm with AE on this one.
I did this very thing yesterday, in fact.
I used the original base plate to mark the mounting holes.

Also, Home Depot and Lowe's usually have a scrap bin where they put cutoffs from plexiglass, if that will work for you, you can often get some scraps for free.

[Brewski]

Yeah I'd not really thought about the router bit size but I'll install my 1/4" straight cut bit and measure back from it for the speakers cut out size. Currently the plan for the the buyout MTM is to surface mount so I'll need a 5.75" cutout for the woofers. For the tweeters I've found that my 3" hole saw combined with my smallest rabbet bit bearing is working fairly well for getting a 4.1" cutout for flush mounting.

Take it easy
Jay

[Brewski]

Instead of messing up the original base plate, why not just make yourself a throw away base plate form a scrap of wood or whatever. You wouldn't even need to screw it down, something as simple as double sticky tape would hold it in place. Or you could get fancy and make a nicer add on base plate from some plastic or Masonite. When I want to make something, I go to my local plastics store, they have a bin of scraps that they sell real cheap.

Well I've already got three plates that came with the router. One of those plates I've never put on since I've mainly been using rabbet bits and the center hole is too small for the rabbet bits... So rather than buy or make a jig out of left over masonite in the garage I was thinking I could use one of the plates I was already considering extra/scrap drill some holes in it and have a jig for a few different sizes of cutouts.

[WWWJD]

I made one for my crappy Black & Decker for bigger holes (seen in this photo), and ultimately it wound up being peppered on the ID of the router base plate area for all kinds of goofy smaller diameters. Since then gotten a Jasper, but you can't beat the sheet metal beater for the oddball stuff.

[PWR RYD]

I'm kinda Swedish (no offense meant Lasse), meaning cheap, so that is exactly what I have done. I use a 1/8" drill bit to drill the hole in my cheapo plastic router base plate as well as the center of the hole to be cut, then tap the bit into that center hole. Unfortunately it limits me to routering holes from about 1.75" to 11.5". I use my dial caliper to measure from the outside flute of my plunge cutter to mark the drill point on my router base. I have had very good success with this, unfortunately my router base is starting to look like Swiss cheese (no offense to any Swiss folks out there )

[kirk78h]

I read a tip in a woodworking magazine years ago that is extremely cheap (almost free) and works very well:

1. Install a router guide bushing on your regular router baseplate (centered carefully and securely);

2. Near the end of a scrap piece of wood (usually 1/2 MDF), drill a hole to match the diameter of the bushing;

3. Accounting for the bit, drill a hole offset to the bushing to accept the center pivot pen (a 1/8" hole for a finish nail, as stated above);

4. Drill a matching hole in the center of the circle to be cut;

5. Make sure to account for the width of the scrap when setting the depth;

6. Use several passes to cut through thicker material.

If you are going to cut several holes of the same size for a project, label the offset holes you drill for reference.

Good Luck,
Kirk

[Brewski]

The process worked fairly well. I drilled a hole in the extra plate and used a nail mounted in the hole prior as the pivot point. I had some scrap MDF to try practice cuts on and the process went fairly smooth. In general I need to get used to pushing in towards the center of the cutout as the last of the material is cutway.

I got one of the baffles cut last night prior to taking over baby watching duties after work. I'm hoping to get the other baffle done tomorrow or Sat. On a side note I was happy I had a respirator on considering the amount of MDF dust I was covered in by the time I was done.

Thanks for the help
Jay

[skatz]

I saw a novel circle jig in a woodworking magazine earlier this week.
It consisted of a plexiglass plate, circular, set into a piece of wood that had a cutout and recess; in fact, it looked exactly like you would make to recess mount a woofer. There was an adjustment to tighten/loosen the wooden mounting plate to take up any play, and the circular plastic disc was used to mount the router. Then, turning the plexi circle would turn the router through a circle of whatever desired diameter.
Most circle jigs use a center pivot point and the router on an arm of various spacings; this was different but I haven't tried it to know how well it works. It would allow you to get down to very small sized cutouts.

Steve