Super cheap digital circle routing.
Posted: Fri Jul 29, 2011 5:11 pm
In a quest for accurate circles I came up with this easy and cheap option.
$99 laminate trimmer, $10.99 digital calipers from Hong Kong and some scraps of 3mm perspex.
I took the screws out of the end of the digital calipers and gradually drilled it out to 3/16"
I took the base of the laminate trimmer apart and made a new base from 3 thicknesses of 3mm perspex with a nice snug slot for my digital calipers to fit in.
I drilled and tapped a hole and reinforced it with a nut for my locking mechanism.
I chose a radius close to what I needed. my slot stops roughly 20mm from my bit center so I added 20mm more.
Push into the slot and lock in place. Engage the pin and cut a circle to use for calibration. My idea was to file or shim the end of the slot to 20mm from the center of the bit but when I measured my test circle the 20mm gave me the exact 76.2mm inner diameter that I need with a 3/32 bit in so I am going to leave well alone.
Art shot of the underneath.

$99 laminate trimmer, $10.99 digital calipers from Hong Kong and some scraps of 3mm perspex.
I took the screws out of the end of the digital calipers and gradually drilled it out to 3/16"
I took the base of the laminate trimmer apart and made a new base from 3 thicknesses of 3mm perspex with a nice snug slot for my digital calipers to fit in.
I drilled and tapped a hole and reinforced it with a nut for my locking mechanism.
I chose a radius close to what I needed. my slot stops roughly 20mm from my bit center so I added 20mm more.
Push into the slot and lock in place. Engage the pin and cut a circle to use for calibration. My idea was to file or shim the end of the slot to 20mm from the center of the bit but when I measured my test circle the 20mm gave me the exact 76.2mm inner diameter that I need with a 3/32 bit in so I am going to leave well alone.
Art shot of the underneath.
