Pattern template size

[Born2bye]

Hello all
Can you help on this.
I want to make a pattern template that will cut out inlays with a circle dia of 80mm.
I will be using a 30mm bush and a 10mm cutter to use on the inside of the pattern template Circle.
What size should the template circle be to ensure my inlay is 80mm please.

 

[Distinterior]

If I understand your description correctly, you would need a circular template of 120mm dia.....

 

[Born2bye]

If I understand your description correctly, you would need a circular template of 120mm dia.....

So would the calculation be
80mm circle + 30mm bush +10mm Cutter = 120mm

I was thinking 80mm circle + 30mm bush - 5mm (Half of cutter for centre line ) = 105mm or -10mm for cutter = 100mm

 

[Distinterior]

80mm circle + 30mm bush +10mm Cutter = 120mm

40mm Radius + 5mm (1/2 dia of 10mm cutter) + 15mm (1/2 dia of 30mm guide bush) x 2 = 120mm.

 

[Born2bye]

40mm Radius + 5mm (1/2 dia of 10mm cutter) + 15mm (1/2 dia of 30mm guide bush) x 2 = 120mm.

That makes sense, i understand now, thank you very much

 

[Doug71]

If you are cutting out a hole for something 80mm dia to go in you need a 100mm diameter template.

If you are cutting out a circle to fit in an 80mm dia hole you need a 120mm diameter template.

I think.......

 

[Linus]

https://www.wealdentool.com/kb/rons-tips/general/guide-bush-cutter-offset/

 

[Sgian Dubh]

To cut a circular piece of inlay to fit into an 80 mm diameter recess using a 30 mm guide bush and a 10 mm diameter cutter you need a disc template that's 70 mm in diameter. Just how you would safely and firmly hold the 70 mm diameter template and the part it's attached to being cut whilst using the router is another matter. A 70 mm diameter template disc is a small base upon which to run the base of a router leading to likely instability. There are solutions to the instability issue, but that wasn't part of your question.

To cut an 80mm diameter recess in a field you need a 90mm diameter hole cut in your template material.

The sum is (guide bush diameter - router cutter diameter)/2 = offset. Therefore, (30-10)/2 = 10 mm. Slainte.

 

[Distinterior]

To cut a circular piece of inlay to fit into an 80 mm diameter recess using a 30 mm guide bush and a 10 mm diameter cutter you need a disc template that's 70 mm in diameter. Just how you would safely and firmly hold the 70 mm diameter template and the part it's attached to being cut whilst using the router is another matter. A 70 mm diameter template disc is a small base upon which to run the base of a router leading to likely instability. There are solutions to the instability issue, but that wasn't part of your question.

To cut an 80mm diameter recess in a field you need a 90mm diameter hole cut in your template material.

The sum is (guide bush diameter - router cutter diameter)/2 = offset. Therefore, (30-10)/2 = 10 mm. Slainte.

If I have understood Born2bye correctly, he said he plans on running the router guide bush against the inside of his circular template to cut a circular inlay of 80mm dia, in which case, 120mm dia hole in his template would be correct.....?

In the scenario that you describe Richard, to cut out an 80mm dia inlay piece, I believe that your "disc template" would need to be 60mm dia, not 70mm.

 

[J-G]

As is often (Always??) the case, 2 minutes spent drawing the problem provides all the answers - - -

I'm sure I don't nee

d to explain further.

 

[Sgian Dubh]

If I have understood Born2bye correctly, he said he plans on running the router guide bush against the inside of his circular template to cut a circular inlay of 80mm dia, in which case, 120mm dia hole in his template would be correct.....?

In the scenario that you describe Richard, to cut out an 80mm dia inlay piece, I believe that your "disc template" would need to be 60mm dia, not 70mm.

Yes, my mistake. Brain burp on my part, probably because it was early morning. J-G's later drawing makes things clear with 100 mm being the correct diameter for the hole in the template to cut the recess for an 80 mm diameter inlay. Slainte.