I got a bunch of Forstner drills over the years at yard sales. Some have round shafts, some have four sided shafts.
Are the four sided ones for use in a brace? The old hand style drill?
I need to drill some railroad ties, and some thick telephone poles. Do these chuck up safely to a regular drill, or does it take a special drill to run these bits?
Steve
Forstener's are not good for drilling deep holes like that. Assuming soft wood, use an auger bit.
Yes four sided is for a brace if the four sided tapers.
I have seen forstner bits that are used in a special lock and doorknob drilling jig that have four sided non tapered tops. An adapter goes in the drill, then the adapter quick connects to the 2 1/8th and the 1" bit, for drilling the face of the door and the edge for the plunger, respectively.
My experience with drilling dozens of crossties is that whatever bit you use will be destroyed before the project is finished.
And on more than one occasion the drill that was used.
YMMV
That's pretty much true, but there are a new set of bits out there. These auger bits are not full twist unsupported. They have a shaft that supports the auger, so they will not twist out of shape. See the new IRWINS.
I'm betting that there is an auger made especially for these thick woods, made for the landscapers who drill them all the time.
The trick is to slowly drill so as not to overheat the bit, a big D handled drill. And a very sharp bit self feeding.
I would not use a forstner bit on a rail tie.... I would use like an electrician drill bit....nail cutter, lots of material removal capability. You can find these at garage sales and tool sales... Rail ties are tough, and could have rocks embedded.....and or steel. john
I got a bunch of Forstner drills over the years at yard sales. Some have round shafts, some have four sided shafts.
Are the four sided ones for use in a brace? The old hand style drill?
I need to drill some railroad ties, and some thick telephone poles. Do these chuck up safely to a regular drill, or does it take a special drill to run these bits?
Steve
wrote
If you use a homeowners drill, that is near certain. It must be a drill with a heavy, low speed gearbox, and it helps to run the drill in free air - no load for 15 seconds after each hole to cool the motor.
Interesting. I've never seen a forstner with a square shaft. It would be difficult to use a forstner in a brace because there's no self-feed screw. Without seeing one, my guess is that the square shaft was designed for use in a post drill:
These had a mechanism that coupled the crank handle to downfeed the drill as it was turned.
If you're looking to drill clean holes in thick timbers,
"Larry W" wrote
I don't know if the on the OP was talking about is the same kind of bit I was talking about, but I'm telling you a fact. A square shaft foster besides for a post drill does exist.
I had a door-know drilling setup (at school) that had a captured forstner for the knob hole and another for the plunger hole. They had a proprietary square shaft with a groove under that as I recall that held the bit in the quick connector. You put a quick connect in the drill (proprietary) and each of the bits fit this quick connect. You clamp the jig on the door, drill one, then the other, without having to use a chuck key to change bits...
I never used it. Not precise enough, or adjustable enough to suit each different situation. I like to measure.
3 sided and six sided shafts are common, but I haven't run across 4 sided.
There's all kinds of special tools and rigs out there. One thing for sure, I've seen enough to know that that there's always something I haven't seen...
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