So you need a perfect circle but you dont have access to something like a cnc machine? This ible will show you the way!
I needed a perfect circle for a hurdy gurdy (will be an ible some time soon) to be used as the wheel, but the biggest powertool I have is a drillpress..... nothing like a cnc / lathe etc. This ible will illustrate my failed attempts and final success at making a (near) perfect circle!
Step 1: Tools & Materials
Saw (jigsaw helps, but isn't necessary)
Something round to trace (I used a cd)
Glueclamps / clothespins
Wood (I used really cheap plywood)
Step 2: Drawing and Cutting
Alright start by figuring out what size your circle needs to be, mine needed to be (about) the size of a cd, so that was easy. You can make a circle by tracing anything round, just make sure the radius isn't bigger than the size of your drillpress.
Once you have a circle drawn out cut it out! I actually needed it to be a bit thicker so I cut out 2 circles.
Step 3: Marking the Center
To get the center you could use math or measuring techniques, I (nearly) always use this method:
Trace your circle onto some paper, cut it out and fold it in half 2 times, where the two lines intersect is the center of your circle.
Align the paper circle with the wooden one and push your pencil through the paper to mark the center on the wooden one. Drill this mark, do the same to the other wooden circle and go to the next step.
Step 4: Gluing
This step is sort of optional, I needed to have a thicker circle so I needed two layers.
Simply take your two circles, add some glue, place one on top of the other, add a screw to make sure they are aligned and clamp it down with some glueclamps / clothespins.
Step 5: Shaping
Alright so this is where the circle gets "perfect", once the glue has dried take the rough circle to your drillpress.
Using the screw secure it in the drillpress, make sure is it level by raising the platform to support the circle. Once the circle is secured lower the platform about 1.5 cm (.5 inch) so the circle has room to spin.
Turn on you drillpress and gently push your file against the spinning circle, use the platform to keep your file at a 90 degree angle to the circle. Keep this going untill the edge of your circle is completely smooth.
You can use a couple of strong magnets to keep you file in place, work smarter not harder!
Step 6: Filling the Voids
You can skip this step if you use better quality plywood, mine however had a lot of voids. Take you circle and fill any voids with woodglue and give it another spin on the drillpress+file.
You can use sandpaper to get an even smoother finish or you can go to the next step and find out how not to make a circle!
Step 7: Failed Atempts
Ok now that you know how to make a near perfect circle its time to show you my failed atempt!
I thought I could use my drillpress in the same manner as a cnc to cut out the circle. This method did work a bit, it did cut the wood as expected but it was really impossible to rotate the wood so it could cut out a good circle.
Hope you learned something from my success (and fail) !