The Problem with Circle Jigs...

[tomzarbo]

I like my new Jasper circle jig, (I have the small one, I made my own for larger circles) but what I find a big pain, as well as dangerous is the fact that the router is rigidly attached to the jig. I think the router should rotate in the jig so you can always have both hands on the router, as well as always have the plastic sheild between the bit and my eyes.

Does anyone else think this is something of a design flaw in current circle cutters?

I envision a base that attaches to the router, basically a plastic or alum. disc that fits perfectly into the actual base of the system that is similar to the Jasper jig. As long as the fit is tight, and there is no dust in the bottom piece, the fit should be good enough to make perfect circles. A little down pressure should be enough to keep things kosher.

Does anyone else agree?

It would even make it easier to line up the peg on the bottom part of the jig because the router wouldn't be in the way. I hope I'm explaining this okay... I can see it in my mind!

TomZ

[tomzarbo]

http://i49.photobucket.com/albums/f257/TomZarbo/CircleJigIdea.jpg


I drew a little pic to explain. The disc would screw into the bottom of the router, think 1/8" to 1/4" thick or so. The base would use the same pin system that the Jasper jig uses. You could set up your cut and then just set the router's attached disc into the base, then go to town. The router would always be facing you, it would rotate in the base, and it would make life much easier I think. I realize this would not work well for very small holes, but I think the disc could be modified so that you could at least do a standard tweeter hole up to large woofer hole sizes. The disc could have a large part that screws to the router, and a small round part 1 1/2" or so that mates to the base enabeling smaller holes to be done.

I think I'm on to something here. I'm just too busy to make one as a prototype.

What to you guys think?

TomZ

[marvin]

The idea makes sense, but the moving disc must be perfectly round with the router exactly centered to prevent any variance in radius as it rotates. The rigidly mounted jigs don't have this problem because the same edge always faces the pin.

Its a similar principal to using the same edge of the router against a straight edge in case the router base is not perfectly mounted.

Marvin

> I drew a little pic to explain. The disc
> would screw into the bottom of the router,
> think 1/8" to 1/4" thick or so.
> The base would use the same pin system that
> the Jasper jig uses. You could set up your
> cut and then just set the router's attached
> disc into the base, then go to town. The
> router would always be facing you, it would
> rotate in the base, and it would make life
> much easier I think. I realize this would
> not work well for very small holes, but I
> think the disc could be modified so that you
> could at least do a standard tweeter hole up
> to large woofer hole sizes. The disc could
> have a large part that screws to the router,
> and a small round part 1 1/2" or so
> that mates to the base enabeling smaller
> holes to be done.

> I think I'm on to something here. I'm just
> too busy to make one as a prototype.

> What to you guys think?

> TomZ

[Pete Schumacher ®]

> I drew a little pic to explain. The disc
> would screw into the bottom of the router,
> think 1/8" to 1/4" thick or so.
> The base would use the same pin system that
> the Jasper jig uses. You could set up your
> cut and then just set the router's attached
> disc into the base, then go to town. The
> router would always be facing you, it would
> rotate in the base, and it would make life
> much easier I think. I realize this would
> not work well for very small holes, but I
> think the disc could be modified so that you
> could at least do a standard tweeter hole up
> to large woofer hole sizes. The disc could
> have a large part that screws to the router,
> and a small round part 1 1/2" or so
> that mates to the base enabeling smaller
> holes to be done.

> I think I'm on to something here. I'm just
> too busy to make one as a prototype.

> What to you guys think?

> TomZ

That's similar to how the rotozip circle jig works. There's way too much play for it to work well, but then again, you don't use a rotozip to cut perfect circles.

If the circular base consisted of two pieces separated by a good, wide, stout bearing, allowing the upper and lower pieces to turn with respect to each other, the bottom of the circular base could be rigidly attached to the jig you pictured while the top, connected to the router housing, would be free to swivel.

[blair]

I always thought it would be neat to have a router with a base that could rotate like what you are saying. With a removeable pin or something that would lock the base if needed. It would not be hard to manufacture at all and it is not like the only application is speakers. Could work.

Blair

[bobbarkto]

Provided Link: Router Jig (http://www.tcgweb.com/router_jig.htm)


A variation on the theme but could be easily adapted.

<A HREF="http://www.tcgweb.com/router_jig.htm">http://www.tcgweb.com/router_jig.htm</A>

[Mr.Thomas Aaron Hero]

I saw one just as you illustrated somewhere recently, If I remember I will post a link to it but with my mushy brain that memory might take some time!

Aaron

[benz]

mount the router on a ridged arm, center the baffle on a lazy susan and rotate the MDF. Would be safer but you would need a lot more room ;) .

[pecker]

Provided Link: http://mywebpages.comcast.net/kidder/Audio/Tools/C (http://mywebpages.comcast.net/kidder/Audio/Tools/Circle%20jig/sitandspin.htm)


> I like my new Jasper circle jig, (I have the
> small one, I made my own for larger circles)
> but what I find a big pain, as well as
> dangerous is the fact that the router is
> rigidly attached to the jig. I think the
> router should rotate in the jig so you can
> always have both hands on the router, as
> well as always have the plastic sheild
> between the bit and my eyes.

> Does anyone else think this is something of
> a design flaw in current circle cutters?

> I envision a base that attaches to the
> router, basically a plastic or alum. disc
> that fits perfectly into the actual base of
> the system that is similar to the Jasper
> jig. As long as the fit is tight, and there
> is no dust in the bottom piece, the fit
> should be good enough to make perfect
> circles. A little down pressure should be
> enough to keep things kosher.

> Does anyone else agree?

> It would even make it easier to line up the
> peg on the bottom part of the jig because
> the router wouldn't be in the way. I hope
> I'm explaining this okay... I can see it in
> my mind!

> TomZ

Keith Kidder attempted this some time ago. You can read about it here:
<A HREF="http://mywebpages.comcast.net/kidder/Audio/Tools/Circle">http://mywebpages.comcast.net/kidder/Audio/Tools/Circle</A>%20jig/sitandspin.htm

[tomzarbo]

Yeah, that's the basic idea I was thinking of, but he greatly simplified it by using the existing Jasper Jig.

Thanks for posting that!

I think that if this were worked on a little, and set up right, it would work well.

I'm going to work on my idea in my spare time.
I'll keep you guys posted if I get anywhere with it.
TomZ

[porper]

[pecker]

http://www.eagleamerica.com/images/500/400-1411plus.jpg


> Yeah, that's the basic idea I was thinking
> of, but he greatly simplified it by using
> the existing Jasper Jig.

> Thanks for posting that!

> I think that if this were worked on a
> little, and set up right, it would work
> well.

> I'm going to work on my idea in my spare
> time.
> I'll keep you guys posted if I get anywhere
> with it.
> TomZ

If you could find a router template guide that was the same size as the jasper jig hole you'd be set. Maybe slightly larger, then sand it down to fit.

[tomzarbo]

I used a program called Corel Draw. It's vector based, but once you're done, you can one-button convert your drawing to a bitmap that works with photobucket. It looked better before I shrunk it down small enough to photobucket it.
TomZ

[Pete Schumacher ®]

> I used a program called Corel Draw. It's
> vector based, but once you're done, you can
> one-button convert your drawing to a bitmap
> that works with photobucket. It looked
> better before I shrunk it down small enough
> to photobucket it.
> TomZ

You can post rather large files on photobucket, but BMP is a very inefficient format. If you convert to GIF or JPG formats, you can post just about any screen size you want.

[tomzarbo]

I did use the JPG format, which is really a bitmapped format, not by name, but by function. Sorry, bad terminology on my part.
I tried slightly larger jpg's but they didn't work correctly unless I shrunk them down.
TomZ

[brianwalter]

> If you could find a router template guide
> that was the same size as the jasper jig
> hole you'd be set. Maybe slightly larger,
> then sand it down to fit.

What you need to do is make an Adapter Plate that fits between the router and the Jasper jig that has a hole the same size as one of the router template guide bushings.

To make the Adapter Plate, drill or machine a hole in the center of the blank Adapter Plate the same size as the outer diameter of a guide bushing. Then install the guide bushing on your router base plate with the base plate removed from the router(assuming that you can do this). Next place the router base plate and guide bushing on the Adapter plate, inserting the busing through the hole in the Adapter Plate. With the two pieces now aligned with each other, use the router base plate as a template and drill the mounting holes for your adapter plate. Then mount the adapter plate to your Jasper Jig using the same holes you would use to mount your router to the jig and your all set.

To use the adapter, simply install the guide bushing into the router and set it on top of the now combined Jasper Jig and Adapter Plate and Jasper away. Note, that the Adapter Plate needs to be thick enough so that the guide busing doesn't extend all the way through it and the Jasper Jig.

Note, you will still have the alignment error problem someone else mentioned at the beginning of this thread, but if you aren't too picky, it should work OK.

Brian Walter.

[Pete Schumacher ®]

> I did use the JPG format, which is really a
> bitmapped format, not by name, but by
> function. Sorry, bad terminology on my part.
> I tried slightly larger jpg's but they
> didn't work correctly unless I shrunk them
> down.
> TomZ

The bucket will allow you to upload a 1MB file, a rather large raster JPG.

[tomzarbo]

Maybe it was something else I was doing, but until I shrunk it down to the size you see, It would upload, but where the image usually is, it just said 'no image available' or something like that.
I know I've uploaded pics of a much larger size than that, but...

[rory]

I used some plexiglass from the Lowe's to make a circle cutting jig on my last sub project, which was for a friend. I simply measured the distance, and made a hole in the plexi. Then I drilled a hole in the MDF, where I wanted the hole to be centered. I put a nail inside, and voila' - a poor-man's Jasper jig. It works well for big woofers.

[Paul K.]

the safety issues you stated with the existing Jasper Jig and the way it and the router interreact with the operator have been overemphasized, IMO.
Paul K.

> I drew a little pic to explain. The disc
> would screw into the bottom of the router,
> think 1/8" to 1/4" thick or so.
> The base would use the same pin system that
> the Jasper jig uses. You could set up your
> cut and then just set the router's attached
> disc into the base, then go to town. The
> router would always be facing you, it would
> rotate in the base, and it would make life
> much easier I think. I realize this would
> not work well for very small holes, but I
> think the disc could be modified so that you
> could at least do a standard tweeter hole up
> to large woofer hole sizes. The disc could
> have a large part that screws to the router,
> and a small round part 1 1/2" or so
> that mates to the base enabeling smaller
> holes to be done.

> I think I'm on to something here. I'm just
> too busy to make one as a prototype.

> What to you guys think?

> TomZ