You can buy what is called a goof plate that fits over the side of the door, ask somebody in hardware at one of the box stores.Just make sure the distance from the edge of the door to the center line of the hole is compatible(set back). Or look around for a lock with the proper diameter and set back.

I can't use a plate, I need to refill the hole.

I think I will be OK plugging the hole and redrilling because the new lock is a rectangular pushbutton lock. The mechanism is about 4 inches high.

My question is simply whether I can buy the plug or if I have to buy a hole saw to make the 2 1/8 inch plug.

Make a plug out of hardwood---like oak or ash.

You should be able to buy a dowel - maybe a wood closet rod - that will fit tightly in the hole. A slightly too large one can be sanded to fit. Cut off the length needed and glue in.

It is 2 and 1/8 inches in diameter. They don't make closet rods or dowels that large.

If you have a hole saw that is 2-1/4", the extra 1/8" will take up what the 2-1/8" lacks due to the size of the hole saw itself. In another words you aren't going to get a plug that's 2-1/8 " diameter using a 2-1/8" hole saw because of the thickness of the blade. 2-1/4" will get you a tighter fit,( possibly some sanding). I respectfully disagrre with Handy about using hardwood as it's not really a structural project. You want the plug to be easy to drill out, so using a soft wood will lessen the chance of the glue or epoxy giving out.

I can understand the disagreement. I only recommended that because I have experienced the problem and wound up replacing the softwood plug because the hole saw used to make the new hole made a mess.

It was the same hole saw used again to rebore the hardwood out.

Modern PVA wood glue---the yellow stuff---makes a bond stronger than the wood.

Here is my concern: Unless that wood plug is done extremely well, it represents a weak point. I would not want to have an exterior door that could be easily breached (kicked in) because it had a wood plug in it. I'd get a different lock that fit, I'd use a plate, or I'd get a new door.

I hope this is a painted door.

Use a hole saw to cut a plug a little smaller than the existing hole from the same material as the door.

Use Minwax High Performance Wood Filler to 'glue' the plug into the hole.

Make sure to work filler in so the gap around the plug is filled completely.
Force the filler in from both sides till it bulges out on the other side, then force it back in from the bulged side.

You need the gap completely filled.

The plug is needed since a large hole would take a lot of filler and it would be hard to keep it in unless the door was laying on a surface and you could almost pour the filler in.
Most of the plug is going to be removed when you drill the new lock hole anyway.

Once the filler is set up completely (a few hours) you can locate and drill the new lock hole.

The door is already weakened by the lock holes, and the repair is as strong as the door was originally.
The 'oops' plates do not restore strength to the door, they just save filling the hole only to then remove most of the material.
They do not look as nice if the door is painted.
Once you sand the filler smooth on each face and paint no one will be able to tell a repair was ever made.

Once the filler starts to set you can take a sharp chisel and remove as much of the squeeze out and smear from the door as you can.

"Modern PVA wood glue---the yellow stuff---makes a bond stronger than the wood."

Haha - if thats the case, why don't they save some trees and just make doors out of all glue? Don't take it the wrong way - not intended as an insult, I was just picking on you!

graywings: Go to Rockler online and you'll find hardwood dowels up to 3" in diameter. Many other places also have them from 2", 2.25", 2.5".

mainegrower, I looked online. I can't find a 2 1/8 inch dowel, and I don't have the tools to shave down a 2.25 dowel with precision. My HD sells up to a 2 inch dowel.

I went back to the idea of trying to make the plug, but I can't find wood at HD that is 1.75 inches thick.

I think my best bet is to remove the current lock-and-handle, plate it, and then install the new one above it. That would also remove the issue of the hole being weak that kudzu and cas66ragtop pointed out.

"graywings: Go to Rockler online and you'll find hardwood dowels up to 3" in diameter. Many other places also have them from 2", 2.25", 2.5"."

And if you use a dowel the grain will be going the wrong way (end grain on both sides of the door).

Use a hole saw to cut a plug of matching material.

Another consideration is what material is inside the existing door where the existing hole is. Back in the day and still today, most quallity doors had solid woods framing the areas where locksets would be drilled, but on cheaper doors today, the whole door inards are particle/press wood. If that's the case with your door, the plug ideas are out the window as it wont adhere decent to the press wood.

If there is building going on in your area you can look around for a site that is using 1-3/4" lvl laminated ply material and get a scrapper peice or possibly a lumber yard will have some cut-offs if you go the plug route.

The above is assuming your door is a masonite type solid core door, not solid wood.

Why not find a woodworker or experienced handyman to make and install that plug.

All due respect, you seem to not have the tools or knowledge to do that job.

Use a hole saw to cut a plug of matching material.

As I mentioned above, I can't find anything to buy in Home Depot that matches the thickness of a 1 3/4 inch door. The best I could do is find two wood plinth pieces that might have been 7/8 inch thick.

Handymac, I may not have the tools, but with all of you to help, I certainly have the knowledge. ;)

"I can't find anything to buy in Home Depot that matches the thickness of a 1 3/4 inch door. "

Use multiple pieces (use a good waterproof glue to join the pieces like Titebond II or III (NOT just typical 'carpenter's glue or 'wood' glue) before you use them to plug the hole.

If the stack is a little thicker than needed you can sand or chisel off the excess after the plug is in place.
A wood chisel used bevel down will do a good job at shaving it flat, ad then a little sanding.

Two pieces of 1x lumber (3/4 in net) and a filler piece of 3/4 in plywood between them would stack to 11.75, or you can just omit the 1/4 in plywood and fill the 1/8 inch on each side with filler.

graywings---good attitude!!!!!

Get a couple clamps(to clamp the layers of wood brickeyee described).

Do the over sized hole saw idea.

Buy a ROS(random orbit sander) to use. You will find other uses for that tool later.

Sand the plug to thickness before installing, finish sanding should be minimal to not sand through any veneer on the door.

I have a random orbit sander, but I didn't realize you could take off a measure-able layer of wood with one.

And it never occurred to me to do three layers (smacking self on forehead).

"I didn't realize you could take off a measure-able layer of wood with one. "

All it takes is time.

Our Home Depot sells 6 or 8 in wide fascia boards (boards that are wide & thick that go just under the eaves) that are 2 in thick(less of course these days) often people cut them so you might find small piece perhaps 1 ft long or less & could use that to cut your plug.

Even I was stuck in a similar quandary, last year. Rather than boring a new hole, I made a dowel out of oak wood slightly longer than the thickness of the door and inserted it into the hole with slight strokes of framing hammer and cut the extra length and it worked perfect in my case.

Jacob- Aside from the fact that this is an 8 year old thread, it would be helpful if you provided specifics.

It's spam. If you click his link it will take you to a locksmiths website.

millworkman- Thanks...somehow I missed the telltale link. But I guess the post has disappeared because you reported it :-)