How do I Cut a hole in the dash

[halfor]

I am updating the old 77 Muskie 550 with a tach. This boat has no gauges currently. I will be relocating the light switch to allow room for the new tach. My question is how does one cut a 3-3\8 hole in the dash? The dash is fiberglass over plywood I think? I know it?s thick and I see wood behind it. No real room for a saw, a hole saw measuring 3-3/8 is not available. May be a dermal with roto cutting bits?
Thanks,

 

[gstrom11]

Re: How do I Cut a hole in the dash

Trace the size of the hole and then pull the old switch out so you have a starting point for a keyhole saw?

 

[metriccrescentwrench]

Re: How do I Cut a hole in the dash

a hole saw measuring 3-3/8 is not available.

www.mcmaster.com part number 4066A51 $7.67. There are several other styles to chose from if that one doesn't meet your needs.

Before you cut cover the area with painters tape to protect it from scratches etc.

 

[Grand Larsony]

Re: How do I Cut a hole in the dash

Rotozip tool (or dremel with the right bit) could work but be careful. Sneak up on the cut line and watch the backside so you don't cut anything you shouldn't.

 

[Home Cookin']

Re: How do I Cut a hole in the dash

the limitation on the question is like asking how to dig a hole but without a shovel. But if you must McGuyver it, drill a hole with a paddle bit and then enlarge it with a jig saw?

Anyway, one important step is to avoid splintering the top layer of the fiberglass. Running a hole saw in reverse first is a good method.

 

[halfor]

Re: How do I Cut a hole in the dash

I have never used one of these, do you think this would work for the hole in the dash?

 

[RayNMesa]

Re: How do I Cut a hole in the dash

I used this and filed out the last 1/8"
http://www.homedepot.com/h_d1/N-5yc1v/R-202327758/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

 

[Thalasso]

Re: How do I Cut a hole in the dash

You can buy hole saws that big. Like homecookin said,run drill in reverse and score fiberglass before cutting hole. This will prevent chipping of fiberglass. After cutting take a file and bevel edges and this will prevent cracking in future.RayNMasa hit right on the head.

 

[Borgey401]

Re: How do I Cut a hole in the dash

I used this and filed out the last 1/8"
http://www.homedepot.com/h_d1/N-5yc1v/R-202327758/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

This is without a doubt the best way to go about doing it. In my opinion if you're going to do it you need the correct tools.

 

[halfor]

Re: How do I Cut a hole in the dash

I spent 30 bucks to get the proper tools to cut the hole, before I cut I want to see the gauge work. I put the gauge on the harness, put harness on controller, hooked up the muffs in the driveway, fired it up and...........the tach did nothing. I will need to know it works before I cut anything. if anyone knows or can point me in the right direction please do. I will need to search this one out.

 

[kahuna123]

Re: How do I Cut a hole in the dash

Any of you guys ever seen a fiberglass hole saw blade??

 

[RayNMesa]

Re: How do I Cut a hole in the dash

Any of you guys ever seen a fiberglass hole saw blade??

I never have......but I would like to

 

[zagger]

Re: How do I Cut a hole in the dash

Any of you guys ever seen a fiberglass hole saw blade??

Yes - it is like a regular hole saw but instead teeth is has diamond edge, kind of like a metal tile saw blade would.

 

[zagger]

Re: How do I Cut a hole in the dash

View attachment 110389
Here is a picture of one.

 

[produceguy]

Re: How do I Cut a hole in the dash

I am updating the old 77 Muskie 550 with a tach. This boat has no gauges currently. I will be relocating the light switch to allow room for the new tach. My question is how does one cut a 3-3\8 hole in the dash? The dash is fiberglass over plywood I think? I know it?s thick and I see wood behind it. No real room for a saw, a hole saw measuring 3-3/8 is not available. May be a dermal with roto cutting bits?
Thanks,

I found all kinds of diffrenet size hole saws at Hd. That size will be about 20$. If you can't find it maybe use a size smaller and then maybe a file or sand the hole out to fit.
Rayinmesa, I posted and then seen yours,LOL

 

[KDAVID1]

Re: How do I Cut a hole in the dash

I have never used one of these, do you think this would work for the hole in the dash?

You bet. This is my favorite tool for holes for dashes and such if you have the room to work with it (use these for fab. on race cars). You will have to watch out for a wobble but these work beautifully.

 

[MTboatguy]

Re: How do I Cut a hole in the dash

I have three hole saws of that size, you must not be shopping at the right place, because they are available..

 

[RayNMesa]

Re: How do I Cut a hole in the dash

I Think if I were in the "fiberglass hole cutting Business" I would get this

http://www.holepro.com/fiberglass.html