Best Type of Bit to Enlarge a Hole?

[Beausoleil]

I need to enlarge some 7/8" holes in my teak taffrail (that's what I call it anyway) to 1" without splintering in order to replace the old 7/8" stanchions with 1" ones to support a 1" rail, replacing the SS lifeline around the cockpit/stern, which is standard in Formosa 51's and Hudson Force 50's.

The teak is ~ 1" thick. I have on hand a 1" spade bit which I don't even want to contemplate using - it's bad enough drilling a hole in wood, let alone trying to enlarge one where the point can't guide it. Not that it would work, but I don't even have a 1" hole saw - smallest I have is 1.25". I have a 1" standard twist bit, but it tends to splinter wood.

I can't really remove the rail, so I have to drill it in place with a hand drill. Could I use the speed bit with masking tape, duct tape, sail tape - whatever is recommended. Suggestions?

[READY2GO]

I would use a step bit. They usually start out at about 1/8" and go up in 1/16" graduations to any number of sizes. I have one that goes to 3/4", another to 1", and I forget what the other one stops at. You can get them at Lowes or Home Depot. They are made for metal, but I think they would do fine in wood.

[READY2GO]

Not sure if you can drill all the way through where you are drilling. If you can't, cut the step bit off just below the 7/8" graduation.

[redcobra]

Make a pine plug with a 3/4" hole saw bit. Tap it into the hole then use a 1" hole saw bit guided by the hole in the 3/4" plug to make a 1" hole in the teak. Teak is expensive a 1" hole saw is cheap. Or a 1' Forstner bit again using the plug. The key is to center whatever bit you use on the 3/4" hole while cutting the 1"
Use an electric drill with a level on the back to keep the hole plumb.

[Beausoleil]

Originally Posted by redcobra

Make a pine plug with a 3/4" hole saw bit. Tap it into the hole then use a 1" hole saw bit guided by the hole in the 3/4" plug to make a 1" hole in the teak. Teak is expensive a 1" hole saw is cheap. Or a 1' Forstner bit again using the plug. The key is to center whatever bit you use on the 3/4" hole while cutting the 1"
Use an electric drill with a level on the back to keep the hole plumb.

That sounds best so far. I have a bubble level on my hand drill, but I'd have to buy the 1" and 7/8" hole saws...

[Extemporaneous]

You can also take a 1 inch hole saw and start by drilling a hole through a piece of plywood or solid wood, the thicker the better. Now take the piece of of wood with the hole in it and clamp it to/over the hole you want enlarged (centered). With a new hole saw bit and as long as you take your time, this will work. I sometimes take the pilot bit out of the arbor for this. The thicker the wood is that you put your hole in to use as a template the better guide it will make, provided it is drilled perpendicular (could use a drill press). Installing a plug as suggested is a good idea but will work better if the plug is the same density as the wood your drilling.

Good Luck,
Extemp.

[s/v Jedi]

Or... just take your RotoZip tool and be done with it!

cheers,
Nick.

[Wotname]

Tapered round file and work carefully.

[sailing now]

I think I'd use a dremel tool with a sanding drum,

[Sandero]

Depending on the actual conditions a step bit is ideal if you can make it work.

You might also use a router with a collar guide and template and a jig you clamp to the rail - again if you can. The carbide will make a very clean cut.

You need to do some math and trial and error, but the collar screws into the base of the router and is used to follow the larger hole. For example if you need a 1" Ø finished hole and you use a stop collar has a OD of 1" you would need to drill a 1.5" Ø hole as a guide in your template. You need to carefully align/center you jig on the hole to be enlarged and clamp it securely and plumb with the hole you want to enlarge and the put the router with the stop collar into the center of the hole and run it round the template letting the collar follow the 1.5"Ø hole. Set the depth of the cut by positioning the router base.

Practice on scrap first. You can use 1/2" ply for the template.

If you have a router with a straight bit the collar is very inexpensive and a straight bit is about $10 and will be useful in the future as will the collar.

[imagine2frolic]

I used a sanding drum on my drill to slightly expand the hole for my second windlass. It was very quick, and painless.......i2f

[Blue Stocking]

Extemp has given you the professional solution to not only this problem, but a method which can be used to make custom washers, enlarge hull openings for thru-hulls, do-nuts and sheaves from Tufnol and other synthetics and spacers of any kind.
The application of this method is endless.
Thanks Extemp

[Tellie]

Originally Posted by redcobra

Make a pine plug with a 3/4" hole saw bit. Tap it into the hole then use a 1" hole saw bit guided by the hole in the 3/4" plug to make a 1" hole in the teak. Teak is expensive a 1" hole saw is cheap. Or a 1' Forstner bit again using the plug. The key is to center whatever bit you use on the 3/4" hole while cutting the 1"
Use an electric drill with a level on the back to keep the hole plumb.

I think this is the best and the most simple way to do it. I'd second the Forstner bit, they leave a flat bottom once you've reached your depth. The other methods you'll have to account for the extra depth of the pilot bit on a hole saw or the extra depth and large evacuation of material a step bit would produce below the area of needed work. Also the Forstner bit will leave a far cleaner professional looking cut around the edge of the hole. The others will have a tendancy to tear the wood at the point of the cutting edges entry. With the amount of wood on your baot I'd invest in a set of Forstner bits and a few plug cutters anyway. You'll be a lot more happy with the visual results.

[Jolly Roger]

Taffrail is the correct term. If you also have collars on the rail and base, you should replace these because they add strength and cover any imperfections you might make in the rail.
I would use a Demmel type tool with ½” sanding disks, and slowly work round and down, testing the stanchion as you go. That way you should not have any wood splitting. That tool will also fit between the top rail and the base, which a hand drill might not. You then need to enlarge the holes in the collars, but that’s just file work in a vice, or with the Dremmel and a metal cutting arbor.
From a sometimes ships carpenter, my best advice is - slowly.

[mesquaukee]

A forstner bit and a hardwood guide block as per Extemp. Forstner bits if sharpened properly will not chip or tear as a hole saw will (a bitch to sharpen).
The hole saw tooth pattern is slightly larger than the barrel. It will after a few holes tear the bottom of the guide block resuling in slightly larger than a 1" hole when you start drilling due to the initial wobbling. This problem will never occur with a forstner bit.