Replies

1. 
   CSilk82 | Mar 18, 2022 09:34am | #1

   A ~3" forstner (which is what I think you'll need, I made a small clock not too long ago with a mechanism that fit in a 3" recess) is going to be mighty tricky to use without a drill press. Not impossible, but not easy either (or super safe, be careful with your wrists - a drill with a side handle is probably going to be helpful here).

   A router (even a small one) with an upcut spiral bit and a template is probably a lot easier.

2. 
   bilyo | Mar 18, 2022 09:47am | #2

   A forstner bit should work fine. Make sure your log is clamped down and hold the drill with both hands and keep it going straight. Without a flat surface to register to, I think the router would be very awkward and unsteady.

3. 
   _mj_ | Mar 18, 2022 09:48am | #3

   Start your hole, then use a smaller drill to hog out waste inside the ring before going back to the forstner bit, it will cut a lot easier. Pre-drill your center to keep the forstner on track.

1. 
   CSilk82 | Mar 18, 2022 09:55am | #4

   Now that's a clever idea!

4. 
   lat_axe | Mar 18, 2022 11:54am | #5

   Famag make the sort of Forstner that would do the job in one pass - but only up to 50mm (2") diameter, as far as I can see. They're also very expensive - so worth it only if you're going to make many multiples of something that needs such a bit.

   https://www.famag.com/EN/Home/Products?pro=2a2a5802-1906-47af-bfe2-65977f2f22ed

   This style of Forstner bit has an elongated centre point - a small drill bit, to all intents and purposes - that provides an initial guide hole to steer the main part of the bit once it bites. This makes the bit easy to use freehand, rather than with a drill press; and also allows easy drilling at an angle.

   Lataxe

5. 
   jharveyb | Mar 18, 2022 12:36pm | #6

   There seems to be (for the last 20 or 30 years) a confusion/blending of two similar but different drill bit types. A Forstner bit has an extremely small (almost non-functional) center spur (or really "bump" in most cases) and a sharp, smooth rim that cuts the circumference before the two main cutters take out the bulk of the wood. A multi-spur bit has a small but much bigger and sharp-pointed center spur, and a rim with small saw teeth cut in it. I have collections of both. It is basically impossible to start a Forstner bit by hand, as there is nothing to keep the bit from wandering. A multi-spur bit can be started by hand, if done slowly, because the bigger center point can keep it in place, as long as the bit doesn't grab (which could certainly happen boring into the side of a log.) I can't imagine trying to use a 3" bit in a hand drill; hand, wrist, arm, or shoulder damage is too likely. Big 1/2 hp hand drills are dangerous enough with normal size bits.

6. 
   jharveyb | Mar 18, 2022 12:39pm | #7

   I guess there was an assumption that the hole for the clock mechanism needs to be circular. If not, using a smaller multi-spur bit several times would in fact hog out the bulk of the wood. Getting all the holes to the same depth might be a challenge. If you do use a smaller bit, bore the corners first, to make sure the bit doesn't drift inward into an existing hole. Not so likely with a multi-spur bit, but possible.

7. 
   john_c2 | Mar 18, 2022 04:12pm | #8

   Big forstner bits can be pricey, and seldom used. Really tough with a hand drill. I'd use a router to remove whatever you need for the clock works.