Hi, I'm Ryan new to this forum.

I'm starting work with a company, and have been detailed to find bits and drills that we will use to redeck a wood bridge in Billerica, MA.

The new deck will be full 4x6 ACQ pressure treat, and cut ends will be daubed with more 'stuff'.
The existing stringers and bents are old, thus very dry and probably hard.

My question is this: The decking is to replace old worn decking. We will be using "dome head" bolts, and we will be drill through the decking and stringers, with nuts on the underside.
I have recommended using ship augers (or similar) for the drilling (3/4 inch hot double-dipped galvy bolts), due to their length.
The boss has asked about using Forstner-type bits, but I have recommended against them due to their tendency to wander in the hands of the un(der)trained, and the buildup of chips making withdrawal difficult if not impossible, ESPECIALLY in the depths we're going thru.

The ship augers available in the Grainger catalog are only 17 inches overall. Does anyone make longer augers? Can I use extensions?
Ship augers leave slightly nasty holes. Are there any lipped augers that will make cleaner holes?
Also, the boss has some concerns of guiding the bits straight, is there a 'drill press' that'll help get the holes started? I don't need it, but the other guys WILL.
What to use for power? We have air drills and large trailered compressors available, as well as generators. I was thinking more in the line of some Milwaukee Hole Hogs. I used a right angle model helping build the barn, and it was no big deal. The boss is concerned about fatigue among other problems.

I was trained as a machinist, have done carpentry and the like for 8 years now, and know my butt from a hole in the ground. I think that I have a good handle on my skills, but will be working with a bunch of muck savages (glorified ditch diggers) that do foundation repairs.

Comments? HELP!!!!

You never stated the total hole depth. Is it longer than 17"?
There are extensions for things like paddle bits but I'm not sure if you can get one for a ships auger bit.
A ship auger bit could be the best drill long distances, as they are usually very long.
There are standard power drill attachments that make a hand held drill look like and work like a drill press, that is it has a base and will hold the drill at the proper angle (90°) to the wood. But I'm not sure where you can get one.
Another method to making sure the bit is aligned straight or 90° in two directions is to create a jig that will stand by itself next to the intended hole. Some jigs can be made out of wood, but cutting out two triangles the size of a standard speed square from a piece of 3/4" pine board and attaching them to a corner of a piece of 1/2" plywood at right angles to each other. Or I've seen it done to attach two cheap speed squares to a piece of angle iron, one on each leg, creating a right angle (looking down at the two from the top).
Then you place the jig on the wood and I would assume in your case stand over it and the deck facing down and align the drill bit to the jig and bore down into and threw the deck.
The drill bit should be aligned to the jig as it's being turned by the power drill and this will keep the bit 90° in two directions. (If you understand what I mean).

Sounds like an interesting project.
Good luck.
Jim Rogers
(If you need a drawing of such a jig, drop me a private email and I'll create one and send it to you).

Ryan,

Timberwolf tools at www.timberwolftools.com sells a well-made drill guide. They have fixed 90 degree guides and adjustable angle guides. I have one and use it more than I should because it is so easy. (You kind of get addicted) They make one that will take a bit a little over 25" and drill a hole a little over 21". A disadvantage for your job might be that while the bit self-feeds for the most part, once the screw peeks out the other side it is nearly impossible to push hard enough to finish the hole when you are using the drill guide. Not a problem for us, we finish the hole from the other side anyway to avoid blowout, but I imagine it would be hard to roll the bridge over to finish all those holes.

I would not even try a 3/4 forstner bit if I were drilling deeper than 4".

As far as a source for bits, try www.bitsnbores.com. They have auger bits up to 24" and maybe longer. The ones I know of are called pole augers and have a small single down-spur and are twist, not solid center.

I hope this helps, and good luck with those 12 million holes.

Gabel Holder

Ryan

This might be more bit than you need but..
Mag-bit makes a 40” bit in 7/16”-1 1/8 " dia. and 30” " in 9/16”-1 ½ “ they are double fluted and have a solid center.

I don’t see distributor info on their web site but they do have a toll free number (888-624-2487
The link for Mag-bit magbit
Mag-bit