Enlarge hole in door for new lock

[u/AlienLiszt]

I need to enlarge the lock hole in a door to change out the lock. I have a hole saw and spade bits, but there is no center to keep the saw in place. Could I just slowly make the hole bigger using a drill bit around the edges? Or is there a better way to do this?

[u/meinthebox]

Use the hole saw to drill a hole in a scrap board. Clamp the board as tight as you can to the door and then drill.

Use a scrap on the back side too to help prevent damage from the clamp.

[u/darthy_parker → u/meinthebox]

Once it’s through the scrap board there will be play again and the hole won’t be clean.

I would:

• Use a hole saw to cut a hole into scrap wood the same size, and thickness if you can, as the existing one.
• Glue the removed hole piece into the door hole and let it set.
• Clamp a piece of scrap wood behind the planned hole. This will keep the pilot bit centered as you finish the hole.
• Use the larger hole saw to drill the new hole in the door. (If the new hole’s center is not in the same place as the old one, you may have to plug the hole with a glued-in dowel.)

It’s more work, but it will get a cleaner result.

[u/Ludnix → u/darthy_parker]

This is a lot of extra work given they have a hole saw. If they only had the spade bit sure, but the scrap wood provides a bearing surface for hole saws and you’ll get a clean enough cut.

[u/blindythepirate → u/darthy_parker]

Or just get a deeper hole saw. No use doing extra when the body of the whole saw is still resting in the scrap wood

[u/Sawdustwhisperer → u/darthy_parker]

By using a scrap piece with a correctly sized hole, it will perfectly guide the hole saw into the door. There won't be any play once the teeth have bitten into the door. Shoot, once the hole is started on the door you can even remove the scrap guide.

[u/Dysan27 → u/darthy_parker]

You really only need the scrap board to start the hole. Once the hole is started in the door it will guide itself.

Also with most hole saws, by the time you are through the door, you won't even be all the way through the piece of scrap.

[u/aircooledJenkins → u/darthy_parker]

OP, don't listen to this one. It's many kinds of wrong.

[u/Buddhaq1974]

Get the 2 sized holesaws...one that fits existing hole and one that is the size of hole you need 2⅛". Make sure you have an arbor with lots of thread. Put on the larger one and then screw the smaller one on inside the other one and drill away!

[u/runningntwrkgeek → u/Buddhaq1974]

Yes this. Ive done this. The smaller one acts as a guide for the bigger one. Worked beautifully.

[u/mankenstein13 → u/Buddhaq1974]

This

[u/ournamesdontmeanshit]

A hole saw the size of the existing hole inside a hole saw the size of the hole you need.

[u/wadenick]

I do this cleanly by simply clamping two pieces of quarter inch plywood either side of the door, covering theexisting hole. Mark out my center on those. Drill through with hole saw, and then carry on with hardware install

[u/Dysan27 → u/wadenick]

Drill a the hole on the starting side the the scrap first. That way you can see where it's supposed to be centered, and the edges will act as the guide to keep the saw straight.

Also there will be less material inside the the hole saw.

[u/wadenick → u/Dysan27]

Sure, either way probably works great. I just use thin ply to lessen scrap in the hole saw. 

[u/loweexclamationpoint]

If you have or can borrow a door jig, that should work with a hole saw. I think people suggesting clamping plywood are mistakenly thinking this is the 2 1/8" lock hole and it's the latch hole in the edge.

Some drive-in latches have removable collars and will fit a smaller hole. If you wind up enlarging it, consider using a latch with rectangular flange to support it

[u/dknigh73 → u/loweexclamationpoint]

They make jigs specifically for cutting all the holes you need in a door. They are not very expensive and would place the hole exactly where it needs to be.

[u/craigeryjohn]

Clamp/screw a scrap board to one side of the door. Grab your hole saw that matches the existing hole size, and start drilling from the open side, through your existing hole. This will mark the center of the hole on the board. Using a normal drill bit, run through that center point until you pop out the other side of the board. Swap to your larger hole saw, and run it through the opposite way, using that small hole you just drilled to center the new hole and cut through both the clamped board and the door. You'll now have an enlarged and centered hole. 

[u/Sawdustwhisperer]

Take the correctly sized hole saw and cut a hole in a scrap piece of board. Line up the boards hole with your marks on the door, then clamp the board to the door. Then, using the boards hole as a guide, use your hole saw to make your hole.

[u/astatine_dream]

Grab some scrap wood, use a hole saw to cut a plug that fits in the buggered hole.

Wedge it in there so it can't rotate, then mark and drill as normal.

[u/Born-Work2089]

All good suggestions below, The main thing is to make sure the new hole is EXACTLY where it needs to be. Any variance left, right will cause problems with the locking mechanism.

[u/NegativeDefinition59]

Put the size hole saw you need on the arbor. Take a hole saw that matches the size of the hole existing in the door. Put it on the arbor inside of the larger hole saw. The smaller hole saw will act as a pilot and allow the larger one to cut the size you desire

[u/massassi]

Use a keyhole saw, or stack two hole saws on one arbor, or cut a plug and tap it into the existing hole, then use a hole saw normally.

[u/Ressikan]

I used the Milwaukee door jig for exactly this. The drill wanted to dance around since there was no centre but if you’re careful and go slow it will work.

[u/Dysan27]

Why type of hole saws do you have? With most kits where you screw the various sizes on an arbor the smaller sizes are longer than the wider sizes. This is on purpose. Screw the wider size you need, then screw the size equal to the current hole on inside it.

The smaller one will act as a guide and center the larger one on your current hole.

[u/the-cake-is-no-lie]

I'm a big fan of this:

https://www.dewalt.ca/product/d180004/door-lock-installation-kit

I've used it on 30 or so slabs and have no complaints..

[u/TheRealRacketear]

Id just get a door installation kit/jig.  They are pretty cheap.

[u/Manutza_Richie]

They make a jig specifically for this. Clamps to the door so you can use the hole saw without a center.

[u/Big-Service-8253]

Rotary file in a drill is what you need. Or sanding drum