circle template

anyone got a cheap source for perspex / acrylic sheets for circle template making for use with a router ,
someone you've ordered from before and it wasn't mega expensive or crap when it came.
I don't mind cutting the template myself I just need a good source ... thanks
 
Sorry, no, but you can get an adjustable circle cutting jig for peanuts on the internet.

An alternative to plastic is MDF with the working edge soaked in cheap superglue to harden it. The really thin and nasty Poundland stuff seems to be best! This is sufficient to make at least a couple of dozen cuts with a bearing guided bit.
 
Even in a drill press the cheap circle cutter are hard work - I have not tried a 'proper' one as I simply didn't think it would be worth it. The MDF/superglue jig would last almost indefinitely if you used a guide bush instead of a guided cutter. I have successfully used a bearing guided 70mm diameter R25 round over cutter in a handheld 1/2" machine guided by an MDF jig!
 

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Worth mentioning, do not forget to secure the round piece you are cutting to your workstand with double sided tape for instance, otherwise when you apply the last cut, your jig is not secured any longer and the router will shift outward to dent the circle you just made.
 
I built something like this long time ago. Never let me down, I get to sub 0,5mm accuracy if I'm not too lazy. The material is ply with phenolic top coat, used for concrete moulds. The one in the link has smart adapters for a routing guide (for copying, don't know the English term) from most bigger brands, you don't have to attach the router to the jig and the router doesn't circle with the jig.
 
Worth mentioning, do not forget to secure the round piece you are cutting to your workstand with double sided tape for instance, otherwise when you apply the last cut, your jig is not secured any longer and the router will shift outward to dent the circle you just made.
yeah this almost caught me out a couple of times it's easy to think I'll just do one more pass and then your right through thinks tend to go dramatically wrong when they do go wrong with routers
 
Even in a drill press the cheap circle cutter are hard work - I have not tried a 'proper' one as I simply didn't think it would be worth it. The MDF/superglue jig would last almost indefinitely if you used a guide bush instead of a guided cutter. I have successfully used a bearing guided 70mm diameter R25 round over cutter in a handheld 1/2" machine guided by an MDF jig!
just got a 1.5inch radius round over bit from amazon for the front baffle of my current diy speakers .
I'm borderline scared to use it I know I'll probly have to sneak in gently a few mm at a time using a straight edge but if it's not a disaster I'll prob spring for a hundred quid trend one I quite like the look of large roundovers on speakers
 
just got a 1.5inch radius round over bit from amazon for the front baffle of my current diy speakers .
I'm borderline scared to use it I know I'll probly have to sneak in gently a few mm at a time using a straight edge but if it's not a disaster I'll prob spring for a hundred quid trend one I quite like the look of large roundovers on speakers
It will work fine, however you must use a variable speed machine - you don't want something that size spinning with a near-supersonic tip speed! A spindle moulder would be ideal, but should be ok hand held with, as you say, a mm or two per cut. It would help a great deal to lop off most material with a 45 degree bench saw chamfer. Even better if you take a couple of 25 degree cuts either side of that too.
Come to think of it, a bench saw would be an effective but very slow method of cutting BIG roundovers, talking cuts every couple of degrees then finish sanding. Great for those four inch radius edges...
 
that'd actually a really good idea as long as you could stop it wandering around two much . I've glued the baffle from two prices 18mm each one set back so there will be less material to cut out. thanks for the tip about the speed I would have guessed it was the other way so you wanted it spinning as fast as you can
 
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I use a piece of 15 mm baltic birch plywood as my circle jig. It's a piece of scrap I had handy from a speaker project. For the centre pin I use a piece of 1/8" brass rod. Drill rod or even a drill bit with the flutes cut off would work. The pin fits tight enough in a 1/8" hole that I have to tap it in with a hammer and pull it out with pliers. There's no slop there. The only gripe I have about it is that it's pretty thick, so drilling deep holes requires a long router bit.

I do like the adjustable one shown above, though. That's pretty neat.

For the original question, though: Online Metals in Seattle has plastics as well. www.onlinemetals.com. As does McMaster-Carr: www.mcmaster.com. If you approach a local sign shop I bet you can get your paws on a piece of acrylic. That could work. Art supply places often have plastics as well. They tend to charge a premium compared to the more machine shop supply places, though. Oh... And check Bezos' Bookstore and/or ePay. I have a sheet of 3 mm thick white acrylic that I use as a background for product photos. 60x60 cm. I found Amazon to have the best prices, especially if you already have a Prime membership.

Tom
 
I use a piece of 15 mm baltic birch plywood as my circle jig. It's a piece of scrap I had handy from a speaker project. For the centre pin I use a piece of 1/8" brass rod. Drill rod or even a drill bit with the flutes cut off would work. The pin fits tight enough in a 1/8" hole that I have to tap it in with a hammer and pull it out with pliers. There's no slop there. The only gripe I have about it is that it's pretty thick, so drilling deep holes requires a long router bit.

I do like the adjustable one shown above, though. That's pretty neat.

For the original question, though: Online Metals in Seattle has plastics as well. www.onlinemetals.com. As does McMaster-Carr: www.mcmaster.com. If you approach a local sign shop I bet you can get your paws on a piece of acrylic. That could work. Art supply places often have plastics as well. They tend to charge a premium compared to the more machine shop supply places, though. Oh... And check Bezos' Bookstore and/or ePay. I have a sheet of 3 mm thick white acrylic that I use as a background for product photos. 60x60 cm. I found Amazon to have the best prices, especially if you already have a Prime membership.

Tom
yeah that's a good point I think my pivot Is where the slop is coming from . I tried the trend jig that came with my router today and it felt miles better it won't cut smaller enough circles for some of the drivers I want to cut . I might buy a Decent jig it doesnt seem worth the hassle of messing about trying to make one