Circle Cutting Jigs

[Marcus]

Hi All,

I am trying to figure out how to accurately and repetitively cut out rebated holes for mounting speaker drivers with my router (a little Bosch 1/4" 400a). I know from other forum discussions that commercial "circle" jigs are available, anyone know how to make one or if not, where to buy a commercial one in Melbourne?

Thanks

Marcus

[bobmundy]

Marcus
I may be able to help. I have a CNC router, If you need quantity, or if you want accurate templates, I'm able to supply to your requirements. I recently made a set for another speaker manufacturer, and he reckons sliced bread comes second now. I'm in Bacchus Marsh.


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Bob- You won't get a second chance to make a good first impression...

[Marcus]

Hi Bob,

Thanks for the offer but I have a commercial manufacturer I use in Sydney when I need (well, used to need) quantity work done. My problem is that I need multiple size cut outs in unusual piece MDF sizes so I need to be able to do it myself.

Marcus

[Rod Smith]

Hi Marcus.
1 method would be to make templates and use the template guide supplied with your router.
The template can be a piece of mdf, preferably not to thick, say 6 - 12 mm. It could be exactly the same size and shape as the speaker front to allow easy positioning. Or simply large enough to accomodate the hole and sufficient around it to support the router (plus clamping area).Cut a hole slightly larger than the required hole to accomodate the template guide. You can measure or work it out. Once the hole is correctly sized and smooth, locate and clamp the template to the work, with bit and template guide fitted do a light cut just enough to mark the hole. Then with a jig saw remove the bulk of the hole leavin 1 - 3 mm to clean up with the router. Use a bearing guided rebate router bit to make your rebate. To aid in keeping the template from moving around clue some pieces of abrasive paper to it, around 100 grit. Hope this helps. Hungover in Adelaide. Rod

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[Marcus]

Hi Rod,

This would seem to be the conventional jig approach but doesn't really help me as cutting the circles in the jigs requires a circle cutting jig (oops, circular reference there http://ubb.ubeaut.com.au/ubb/smile.gif and I'm in this bind to start with because my freehand routing skill is pretty hopeless!

Also, I need to cut many different sizes and this really means making a whole bunch of jigs for every speaker I build.

Assuming for the moment I could get the jigs made accurately, I am a little unsure of how exactly it works. I have read your post a couple of times and can't quite figure it out. Please bear in mind my router and I are only recent acquaintances!


Marcus

[Rod Smith]

Hi Marcus. Yep this is the conventional jig approach. The good thing about cutting the holes this way is that you can remove the bulk with a jig saw reducing the routing. This is an advantage particularly with the little Bosch. A cirlce cutting jig can be pretty simple, all you need to do is attach (various ways of doing this) some type of trammel (wood, plywood, mdf)which after being fixed to the centre of the desired hole with a screw/nail and the distance from centre to the outside of the router bit is the radius required, rout the hole gradually plunging after each rotation. But, you do have to cut all the way with the router and you will have to support the piece. This could be useful as the template creator. Above I mentioned the jigsaw. Because a jigsaw only removes a small amount of material they cut pretty quick. Mine came with a trammel bar (only a fixed point though a screw/nail would be better)cutting the holes this way might be worth considering? Depends how good the finish has to be? Whadaya think? Rod

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[Marcus]

Hi Guys,

This:
http://www.flash.net/~jaspera/

is the sort of jig I was thinking might be nice to have. Does anyone know where I might get something similar locally?

Marcus

[Rod Smith]

Hi Marcus.
Why not make your own jig. Its a simple concept and doesn't have to be as fancy as those you indicated. A simple one to start and see if the principle works for you in practise. Give it a go and save some bucks. I haven't seen any jigs like those in Oz.
See ya.
Rod

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[rev]

Marcus,

If you haven't yet solved the problem of cutting circles smaller than the base of the router have a look at the jig mentioned in the middle of this page: http://www.wa1.quik.com.au/tod/circle_cutting_jig.htm

Getting repeatable accuracy might be an issue with the sliding adjustment.

[ozwinner]

Try here.

http://www.mik.com.au/

Search for, "Trend Mini Ellipse & Circle Cutting Jig"

Cheers, Al

[clubbyr8]

There is a group in Sydney called the Soundlabs group that seel the Jasper jig specially designed for cutting speaker holes.

There are at : www.soundlabsgroup.com.au/jasperaudio/

Regards

Bob

[soundman]

If I'm cutting a whole pile of speaker fronts I cretainly make a template.

but

for onesies & twosies I use the fence that came with my router.
most fences you can take off all the funny bits & are left with the plain fence.
some routers it will have a hole in it.

mark out your speaker front. I strongly recomend you draw the holes & everything on the front panel.

mark the centres.

select the centre to be cut, drive a screw or nail. hook your fence onto it & adjust the fence for the appropriate size. fix it down, both the job and the waste piece with brads & rout away.

this is ok for drivers down to about 6" smaller than that & the router base gets in the way.

Don't worry a 2hp router with 1/2 inch bit will cut thru 20mm mdf in one go no problem.

I run a vacume box to cope with the chips & dust but thas not esential.

smaller than 6 " you gota go with a template.

[soundman]

just looked at you original post again.

If you want to rebate the drivers flush.

cut your rebate first then readjust & do your thru cut.

[soundman]

Ive just looked again & you have a pof400.

In that case take small bites of any thing you cut. you will fing the stock fence can be turned upside down & comes with a tramel point(well did).

anyway it will at least have a hole in it

[Template Tom]

Hi All,

I am trying to figure out how to accurately and repetitively cut out rebated holes for mounting speaker drivers with my router (a little Bosch 1/4" 400a). I know from other forum discussions that commercial "circle" jigs are available, anyone know how to make one or if not, where to buy a commercial one in Melbourne?

Thanks

Marcus
Rev has guided you to my home page where you can make a simple circle cutting jig as shown on the page.
I have been using that jig for years and yes I do rout circles accurately each time.
All my Jigs are made in my workshop as I have never purchased a Jig as yet.
Tom

[Errol@vac-clamp]

Hello All
A site to look at regarding part replication with a jig and router is http://www.vac-clamp.com/vacjig.pdf
Accuracy of this method is very good. When using two routers (one rough cut, one finish cut) throughput of work can be more than acceptable.
Errol

[silentC]

If you look at the original post, it's dated 1999. This guy has solved his problem and moved on (one would hope).

Errol, just a gentle hint that there are specific forums on this BB for posting details of products you have for sale: Announcements Forum, and Buy Sell 'n' Swap Forum.

[scooter]

SilentC, nicely put. Not offensive, just polite. Goodonya.......Sean

[Sprog]

If you look at the original post, it's dated 1999. This guy has solved his problem and moved on (one would hope).

Errol, just a gentle hint that there are specific forums on this BB for posting details of products you have for sale: Announcements Forum, and Buy Sell 'n' Swap Forum.

But the thread was resurrected 2 weeks ago.

I found the Vac-Clamp PDF quite informative, something to tuck away for later reference.
After all it was just a link, not blatent advertising, I find a lot of the links provided on this forum are very helpful.

Just my thoughts :D

[silentC]

Sprog,

I'm not saying that Errol doesn't have a good product to sell. However he has posted virtually the same message on 5 threads so far. It's not my call as to whether it breaches the "no advertising" rule. That's up to the administrators. If it's fine with them, it's fine with me.

One thing I like about this forum is that we don't get bombarded with people pushing their wares on every thread. I just wanted to point out in the nicest possible way that there are other more appropriate places to advertise his product.

[Errol@vac-clamp]

Suitably chastened I shall ammend my ways. I apologize to those that I have offended.
In future I will only respond if there is a direct reference to the product that requires correcting.
Errol

[silentC]

Errol,

Certainly no offence taken from my point of view. I've seen one or two commercial posters get strips torn off them and wanted to save you the grief.

Cheers