I am going to replace a transducer that will require a larger hole. Usually there is a centered guide bit that keeps the drill stable, however with an existing hole that is being expanded, that is no longer an option. Any suggestions on how to keep the drill stable so the round hole cutter will not wobble? Thanks. Jon
Drilling Larger Thu Hull Question
- Thread starter PGIJon
- Start date
Yes. Fill the existing hole with a slightly tapered wooden plug. Anyone with a lathe can set you up.
A tapered plug surly will work but isn't necessary.
I just did this on my boat last week!
A small chunk of wood that fits snugly in the hole is all you need. From the outside get a short chunk of wood that fits in the hole. Like a chunk of 2x4. Maybe 4" long. Cut it so it fits snugly in the existing hole. Trim the hunk so it fits tight in the old hole with a saw or knife. You can even split parts off the chunk with a screw driver. It easy to taper it a bit for a snug fit with a knife.
Put it in the hole so it's almost level with the hull. It does not have to be perfect. It can stick out a 1/4" for so but it needs to be snug.
Position hole saw so it's centered over the old hole. The center drill bit will go into the wood block. Once the outside of the hole saw begins to bite in the fiberglass the center drill bit is just along for the ride. But it does help the hole saw from skipping out of
position.
Go slow and it works perfect.
I just did this on my boat last week!
A small chunk of wood that fits snugly in the hole is all you need. From the outside get a short chunk of wood that fits in the hole. Like a chunk of 2x4. Maybe 4" long. Cut it so it fits snugly in the existing hole. Trim the hunk so it fits tight in the old hole with a saw or knife. You can even split parts off the chunk with a screw driver. It easy to taper it a bit for a snug fit with a knife.
Put it in the hole so it's almost level with the hull. It does not have to be perfect. It can stick out a 1/4" for so but it needs to be snug.
Position hole saw so it's centered over the old hole. The center drill bit will go into the wood block. Once the outside of the hole saw begins to bite in the fiberglass the center drill bit is just along for the ride. But it does help the hole saw from skipping out of
position.
Go slow and it works perfect.
If you have a hole saw that matches the original hole size, then just stack the smaller saw and the new larger saw together.
The smaller saw will seat in the original hole and keep the larger saw steady.
I've done this before without issue.
The smaller saw will seat in the original hole and keep the larger saw steady.
I've done this before without issue.
If you don't have a proper sized saw to stack, I've just taken a piece of dowel the size of the hole, drilled a hole in the center of it the size of the pilot drill. just slip it it on the pilot and use that to center, once you have a groove started you do not need a pilot. I have done this many times, alot cheaper than buying another saw.
WOW!
Thank you all!
This place and all of you are truly amazing!
No more sleep lost thinking about this one!
-Jon
Thank you all!
This place and all of you are truly amazing!
No more sleep lost thinking about this one!
-Jon
You can also drill a hole the new size in a piece of plywood and set the plywood in position where you want the new hole. Hold the plywood down and drill the hole in the fiberglass using the plywood as the guide for the hole saw..
Oops arbour for stacked hole saws - made for just his kind of situation!
http://www.starrett.co.uk/shop/hs_accessories/oopsarbor/
Available online from lee valley
http://www.starrett.co.uk/shop/hs_accessories/oopsarbor/
Available online from lee valley
havent bought anything from Lee Valley in a long time but they do have very good products
I did just that with 2 concentric hole saw cutters inserted into each other. Make a test cut on another starboard to make sure the device will fit properly. After you make the cut be sure to coat the newly cut surface with 3 coats of epoxy to prevent any water penetration into the hull material. Let it dry then use 3M 4200 quick dry before inserting the device. It does not take much tightening from the other side.