Drilling fiberglass dash for speedometer install

[Rod Clements]

What is the best way to drill a fiberglass dash to install a speedometer? I've never done this, and would like some advice. I have uploaded a picture of the dash in question. Any advice is appreciated.

Thanks,

Rod
Kansas

 

[RPM]

We use hole saws for that. Hole saws come in increments of 1/8" And they will make a hole exactly the size it says on the side of the saw. If you are using the 2 1/16" gauges, you will need a 2" saw and then have to sand the inside to make it bigger.

 

[409T]

You can buy a 2 1/16" hole saw.

 

[baddawgcustoms]

Put down Several layers of blue painters tape over and around the area you are going to drill. This will help keep the paint from chipping and help if you have an oops. Since it's painted, predrill the center with the same size bit as the guide bit for the hole saw.

 

[bobs66440]

Yep, hole saw. But they ain't cheap.

 

[Mikester]

You could also do it like us poor boys do. Put down several layers of masking tape over the area to be drilled. Mark the circle on the tape with a compass or other object that is round and the right size. Drill about 10 million 1/8" or so holes just inside the diameter of the hole you marked, drilling the holes as close together as you can. Be careful that the hole you drill does not go outside the line you drew. After all the holes are drilled connect the holes by removing the material between them with a drill bit, jig saw blade, dremel tool or whatever. Then you will have to go around the hole with a grinder to smooth out the edge. This way you won't have to buy a 4" hole saw that you might never use again. It won't be a real pretty hole, but the rim of the speedo will cover the edge anyway.

 

[Screaming Metal]

Fiberglass loves to eat up cheap holesaws. Go to harbor freight and use a couple of cheap ones to get almost all the way thru, put in the good one, it'll just skim the OD of the hole because the fiberglass trims down the outside of the cheap holesaws.
That way you'll have more left on your new holesaw to do more work with it. Like a matching Tach....;-}

 

[Rod Clements]

Thank you all for the great advice. My son has 2 hole saws that I can use...that way I dull his. Tomorrows the "big day". I'll let you all know how it went. And yes, Screaming Metal... a matching tach is a great idea! Thanks again!

 

[Zandoz]

Has anyone ever used a Roto

Fiberglass loves to eat up cheap holesaws. Go to harbor freight and use a couple of cheap ones to get almost all the way thru, put in the good one, it'll just skim the OD of the hole because the fiberglass trims down the outside of the cheap holesaws.
That way you'll have more left on your new holesaw to do more work with it. Like a matching Tach....;-}

If the fiberglass eats up hole saws, I wonder if a Rotozip would work. Use the hole saw to to cut the desired size hole in a 1x, clamp it on the back side of the dash, as a guide for the Rotozip guide tip bit. <shrug>

 

[Rod Clements]

The dash went excellent without any problems at all. I did drill with a 3" hole saw per recommendations offered on this forum. Thank you all for the excellent help and advice. I have posted 3 pics from the project. I do have questions about side mirrors available, but will post as a specific topic. Once again, thank you everyone for all the help!

 

[Neshkoro]

That's cool. The car is going 55 MPH and there is no one driving it! Just kidding.

 

[choppedtop]

Besides saying good job, I was going to say it was unsafe to take pictures of the dash while driving 55mph. It does look good.
Lee