Thread: Gauge Holes - Fiberglass Dash

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My gauges require 3 5/32" (80mm) holes for the speedo and tach, and 2 1/16" for the four small ones. The big one is an off-size for hole saws, and the little one is a bit hard to find. They're going into a fiberglass dash. Is it best to cut a 2" and 3 1/8" and then sand up the extra 1/16"-1/32"? Any special type of saw to ensure no problems?

just posted how i do it on denny.s

Originally Posted by pat mccarthy

just posted how i do it on denny.s

Read it there first.

cut the hole with the holesaw and take a smaller piece of hose. Wrap some sandpaper around it and finish to the size, putting gauge in every now and then for proper fit...........done

Roger - I don't believe there is a hole saw made that cut the size hole stamped on the body - they are usually a minimum of 1/32 larger based on wobble.

These folks have the 2-1/16" for $6.58 tho no 3-5/32".

http://www.mcmaster.com/#hole-saws/=67q69u

You need the $9.57 arbor as well which is the next page of the catalog.

These were cut for the Billet Specialties overlay panel using the 3.25 and 2.062 hole saws from McMaster and have VDO's in them now. These were pretty accurate and needed only a small amount of filing (steel dash) to clean up

Since it is fiberglass I think I'll go for a bit smaller, like 2" and maybe 3.125" and then sand to fit. I'm a bit concerned with 3.125" for the big ones, as that is only 1/32" small, and they caution not to go too big. Thanks for all of the input.

Originally Posted by rspears

Since it is fiberglass I think I'll go for a bit smaller, like 2" and maybe 3.125" and then sand to fit. I'm a bit concerned with 3.125" for the big ones, as that is only 1/32" small, and they caution not to go too big. Thanks for all of the input.

If the dash comes out, I suggest a drill press. Those #@$% hole saws really like to grab and move around ( I have a scar from a 4 incher to prove that statement ). If not, start it s-l-o-o-w

The bore undersize, and open up with a drum sander is what I did with this '32 dash. I did as Dave suggested, bored slow in the blank out of the car. With this one I did the "insert" piece then sunk it into the dash surface. It looks similar to an old SW panel shape but I had no pattern so just did what looked good to me. As an aside, after bonding it to the dash panel, I formed a 1/4" half round bead around the opening to give it a more interesting appearance. Then got some sheet stock engine turned panel and cut to shape to back the gauges.

I got this from harbor frieght and it worked fine.

http://www.harborfreight.com/cpi/cta...emnumber=37370

Originally Posted by 323wc

I got this from harbor frieght and it worked fine.

http://www.harborfreight.com/cpi/cta...emnumber=37370

You know, I've got one of those but only a single cutter. I had forgotten about it, but it does cut a clean hole in wood. The dash panel is out, and I will be cutting on a drill press. Thanks for jogging my memory.

Originally Posted by rspears

You know, I've got one of those but only a single cutter. I had forgotten about it, but it does cut a clean hole in wood. The dash panel is out, and I will be cutting on a drill press. Thanks for jogging my memory.

Again, if you use one of those, make sure the work is well clamped and use slow speed. I also have one and seldom use it, preferring a hole saw that gives you 360* contact on the work piece. You also might find that on 'glass that you could have more chip out especially if one of the cutters is a bit dull.

Originally Posted by IC2

Again, if you use one of those, make sure the work is well clamped and use slow speed. I also have one and seldom use it, preferring a hole saw that gives you 360* contact on the work piece. You also might find that on 'glass that you could have more chip out especially if one of the cutters is a bit dull.

IC2, I have that concern, too, especially thinking about the imbalance of my single cutter unit. I'll go back into town tomorrow and see what kind of 360* hole saws I can find, knowing now that I want to cut a bit small and sneak into the final size. I figure I can cut a test hole in wood, and "tune" the saw a bit with a flat file & drill press if it is cheating big. When I stopped in Saturday I was looking for exact sizes.

I use Milwaukee hole saws, and in a drill press whenever possible, Rog. My procedure is the same as Dave and Uncle Bob use, works great. Just keep the speed low on the drill press, and light pressure for 'glass.

If you want to use an undersized hole saw you can squeeze it in a vise to make it oblong to cut a slightly bigger hole

practise on a piece of scrap panel to get the size right

guages also have a dimple in one spot to fit into a notch so they stay aligned

Originally Posted by jerry clayton

If you want to use an undersized hole saw you can squeeze it in a vise to make it oblong to cut a slightly bigger hole

practice on a piece of scrap panel to get the size right

gauges also have a dimple in one spot to fit into a notch so they stay aligned

Jerry - I've had S-W, Classic and now VDO in various cars and none have had a dimple (tit?) for maintaining alignment - possibly Auto Meter's or other pro race car gauges have this dimple. I wish they did - like my ignition and headlight switches