Perfectly centred holes

Hi,

Im playing around extruder gears but when I drill out the cogwheels I always manage to get the angle not straight. Its not much but enough to see a slight wobble when its on the motor. Is there some sort of jig or trick one can build/use to align and center the drill besides a drill press?

Cheers

Edited 1 time(s). Last edit at 03/01/2015 01:24AM by sungod3k.

Well what I do when I need to drill a hole in the middle of a circle is. First find my center. Here is a instructible on how to do it [www.instructables.com] . Next I secure my circle in a clamp or vise. If you don't have one you could put a couple nails in a line on a board. Then use a third nail in a hole drilled at 90 degrees to the line the first two nails make to secure your circle snugly. With a Gear the teeth give natural places for your nails to grab and prevent it from spinning. Now you drill go from above and try to keep the drill from wandering as much as you can Drill speed should be as fast as you can without burning the material with friction.

Thanks Mike

It's almost impossible without a lathe. To do it with a drill just by sight is the worst way to go. Even a drill press can wobble from slack. And to get a vise to hold it straight under the bit is tiresome.

It's really difficult to drill in printed parts anyways. Especially for centered holes in cogwheels. I've noticed the plastic tends to deform from heat very easily.

A few tips for drilling in the parts:
- Use a support/jig like you already realized
- Print the walls a bit thicker, so that when you ream or drill out the holes, you don't destroy the walls by accident (combination of heat+friction)
- Use a lathe (best option, but most people don't have this)
- If you drill by hand, try to keep the drill speed low and use a new sharp drill bit, in this way you don't frictionize the plastic away, but really just let it eat away. I usually mount the drill in a big strong bench vice and rotate the part over the drill bit by hand. This has worked out very well for most of my parts.

Edited 1 time(s). Last edit at 03/01/2015 05:48AM by Ohmarinus.

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http://www.marinusdebeer.nl/

Hi,
you can try adding a long cylinder to your design (you'll cut it with a saw at the end).
The cylinder will guide the drill up to the part of the hole you want to be perfect.