Drilling holes in fiberglass

Mike

Lifetime Supporter
Getting ready to mount front canards and rear lip. Probably an elementary question but any special bits that should be used or precautions that should be taken to prevent damage to surrounding paint and fiberglass? Having not drilled fiberglass body panels before I hate learning on $$ production pieces. I had planned on drilling small pilot holes first followed by the desired final size bit. Thx
 
Take the largest drill bit you have and ram it at full speed =)

Or drill a small pilot hole, like 1/16'', then enlarge to 1/8'', then use a unibit to continue drilling. I've had the best success doing that (success meaning a clean hole, no chipping in the gelcoat, etc...)
 

Trevor Booth

Lifetime Supporter
Supporter
Twist drills designed specifically for drilling timber are excellent. They have a small point to prevent wandering and a fast twist to clear the swarf. The set I have are many years old, dont know if you can still buy them. (I dont mean auger bits or flat bits)

If you are drilling large holes use a hole saw which in my country are available from 1/2 inch and upwards.
 
I've done a lot of drilling/cutting of bodywork for my race motorcycle. I've had a lot of success using a Dremel at moderate to moderate-high speed.

As mentioned, tape the bodywork (I suggest taping both inside and out), and use sharp bits. Decrease your pressure as you are about to poke through the back side. This will help with splintering. Not to sound like a parent, but I would also suggest wearing a mask and eye protection.
 
Masking tape on the body, pilot hole, hole saw for large holes and Alex's suggestion of a unibit to use for the smaller holes works fine. Finish up with a sanding drum if necessary. I always make the hole a little smaller, then finish up with the sanding drum on a drill motor (for round holes). For installation of fasteners/rivnuts, etc. Masking tape and a couple of sharp drill bits are all you will need. Pilot hole first if possible.
 
For any hole size larger than 0.5cm I drill a small hole then enlarge it with a dremmel sander rather than a big drill. Definitely no cracking of the gelcoat then. For really big holes like the one I had to make for the marker light, I drilled out the hole undersize with a hole saw, then again, used the dremmel with a sanding wheel to get to the final size. Always use masking tape on the body whatever you do.

Martin
 
Micheal,
Don't know how far along you are with the canards. I looked all through the forumn when I was considering them for my car, and came up with several designs. The ones I liked best were not the straight ones rather the ones that made a gentle curve up the side of the front clip. A forum memeber supplied these drawings to me. Some of the straight canards required adjustable bracing, which I didn't like. My canard is made of two pieces of aluminum welded together. I used a piece of legal pad paper to cut it out for a trial fit. It was cut wide enough to include tabs that were taped to the fiberglass to see the final shape. Here is the outline of the canard.

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As you will see in the folowing pics there is an anchoring strip on the underside.

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The cuurvature will give the canard its strenght to resist bending. Use sticky foam along the fibergalass aluminum border to prevent scratching. All along the ouline on the inside place another strip of aluminum to give the screws somethng to hold on to and resist breaking through the fiberglass.
If you havenot cut your canards there are many different ways of adding them to your car. Several of the car manufacturers have them pre cut if you like. Here are some on originals and replicas. I have many more examples if anyone is interested.

Bill



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Terry Oxandale

Skinny Man
Has anybody tried these with a small end plate (or a 90º brake on the outside edge) to reduce spill-over, and create a more efficient canard?
 

Mike

Lifetime Supporter
Has anybody tried these with a small end plate (or a 90º brake on the outside edge) to reduce spill-over, and create a more efficient canard?

The set I bought from Olthoff has this lip. I have been filing and tweaking on them to improve the fit and will post pictures once I have them recoated and mounted. Thanks for all the drill technique advice.
 
open the pilot with a no.40 or no.30, then upsize the hole to your final diameter using a stepped unibit. perfect holes everytime. also, the tape does keep the fraying to a minimum
 

Jack Houpe

GT40s Supporter
The set I bought from Olthoff has this lip. I have been filing and tweaking on them to improve the fit and will post pictures once I have them recoated and mounted. Thanks for all the drill technique advice.

I have a set also from Dennis, I will wait for the photos and advice.
 

Mike

Lifetime Supporter
The mistake I made was to have Dennis powdercoat them prior to me mounting them. Olthoff builds race cars and a gap here or there on a canard fitment probably doesn't concern them as it relates to winning races. Since my car is as much for looking at as it will ever be for winning races, perfect fitment is more of an issue for me and as such I have filed and ground here and there and now have to re coat them at my own expense. I would buy them raw from Dennis and then when you are happy with fitment then coat, polish, or whatever you like.
 

Mike

Lifetime Supporter
I have the patterns laid out on the car and have finished grinding and fitting the canards. Trying to pull lines to assure symmetrical alignment was a challenge as nothing seems to be square on the body. I finally just picked a starting point using the front mount tab and pulled my lines off the driving lights housings and then off the headlights as I think that will be what draws the eye. I'm going to drill and test fit them tomorrow before sending them back to recoated. There will be some shimming necessary so as not to tweak and put strain on the body panel and risk cracking the gelcoat. I think aesthetically the results will be well worth the effort. Pictures to come once they are test fitted.
 

Mike

Lifetime Supporter
Test fitting is complete now off to powdercoat for refinish. Thx for all the tips. I used a brand new unibit. Worked like a charm with no cracking or fraying. Next, I am pulling the front clip to fix the misaligned alignment pins :) Also, will mount the rear spoiler this weekend and install the caps from Grady on the front hubs. I wish it wasn't January but that leaves lots of time before spring to keep tweaking here and there.

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Micheal,
I think you have done a great job with the canards. Are those backing stips hard rubber or plastic?? I think that is a better way of mounting the canard. A fender washer might work as well to distribute the load. Does it allow for a litte flex? The strips I am using are a bit of a struggle to get mounted. I would guess it pulls the canard closer to the body as the nuts are tightened down. May change my strips to the individual pieces. Did you use anything between the canard and the body, such as foam strips??

Bill
 

Mike

Lifetime Supporter
Bill, the backing is actually a pretty soft rubber under the fender washers. As you said, I did so trying to distribute the forces evening so as not to induce cracking in the panel. On the front tabs I used a thinner soft black rubber that distributes the load more evenly as well. It seemed to me after the initial test fitting that there is not much flex in the body panel and if you were to start cranking down the nuts when mounting it would almost certainly crack something. That lead me to spend a lot of time with a file shaping the canards so they fit perfectly before I bolted them on. The biggest pain was making sure they were symmetrically mounted on each side. Lots of measuring and re-measuring. They came out looking great I think. For anyone interested, you can get a set from Olthoff Racing.

Mike
 
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