Carvex Circle Cutter Attachment - a little inaccurate, also how to avoid a hole?

[eddomak]

Today I just purchased and used the Carvex circle cutter attachment.

Firstly - what a great attachment! - I found it easy to set up, attach, and use. I followed the tips from Peter Parfitt's video and it was great. It tracked well and ended exactly where it started.

My only comment was that it was a little inaccurate in the measurement scale. I wanted to cut a hole to 28.5mm radius, and in the end it cut 28.75mm, which meant the circle was 5mm bigger in diameter than desired. I had used a pencil to mark out the cut line by tracing the mark in the centre of the guide, and when I measured that it was correct, but the cut line turned out a tiny bit too big.

Does anyone else have this experience?

I understand that there are quite a few variables at play such as the thickness and width of the blade, so in the end this is more of a comment rather than a complaint.

I also had a question - is there any way to avoid the 4mm hole in the centre of the circle? With the router, I would stick a piece on top in the centre, and have a same thickness piece at the end of the trammel.

I found this arrangement faster to setup and produced less waste and in less time than the times I have used a router and trammel arrangement. I think I will be using this method for a majority of times in the future where being super accurate is not a concern. Otherwise I will use it to cut an oversize circle and follow with the router for the final cut.

I am very happy with this purchase and do highly recommend it for those that need to cut circles, and am now considering making the parallel guides for the guide rail using another one of these. [big grin]

 

[Gregor]

Your numbers are strange, as the difference would be 0.5mm in diameter - at least I read your post that way:

A hole of 57mm diameter with a jigsaw won't be that smooth IMHO, while the circle can be used it's more useful for bigger circles. It also feels like it's more intended to cut the outside of something (like a table top) instead of creating holes as the loose part (the center) would move at the end of the cut.

You can avoid the hole in the middle by using 1-2 layers of fabric tape to fix a 4mm nail with a big flat head upside down onto the material. Should work as long you you don't pull that hard hard on it sideways.

A router with a template and a bearing copy bit will most likely give better results for such small holes, or using a hole saw of the needed diameter.

 

[eddomak]

Your numbers are strange, as the difference would be 0.5mm in diameter - at least I read your post that way:

Ooops! I meant cm's. Sorry (was working in cms as was given the spec in cm's). So it should be a 57cm diameter, set the radius to 28.5cm (285mm), and the final product was 57.5cm (575mm), which is 5mm too much.

You can avoid the hole in the middle by using 1-2 layers of fabric tape to fix a 4mm nail with a big flat head upside down onto the material. Should work as long you you don't pull that hard hard on it sideways.

Fantastic idea! Thanks!

 

[Acrobat]

If the fabric/nail idea doesn't work for you, -interesting idea by the way, try and double sided tape a small piece of timber down and fit the usual pin in it that way there's no hole in your project.
I've used double sided tape for template routing and it holds remarkably well with routing so hopefully the circle cutting attachment of the carvex will also do the job.