Sign in to follow this  
NOCALSAILOR

drill and tap carbon?

Recommended Posts

 carbon drills and tape.....but I have always used helicoils with carbon . Laminates do not give a particlarly good  bite to threads.  The helicoil,increases holding power .  Use a drop of  locktinght to seat the helicoil...then tefgel or other compound like sikaflex to bed the fastener. 

Share this post


Link to post
Share on other sites

You can also use tri-fold rivets. Generally available in aluminum, some of them painted/coated.

IME regular rivets don't get a good grip and splinter the carbon laminate.

Share this post


Link to post
Share on other sites

Alumium and carbon are not good friends.

i have never, ever come across an alumium rivit or fastener in a carbon mast .

always stainless steel 

any aluminum component that is mounted to carbon must use best practice isolation 

Share this post


Link to post
Share on other sites

Bolt threads will hold just fine in a good carbon laminate. If a 3/8 UNC bolt, 2D thread depth, you will break the bolt long before the threads strip. I have that sort of thing all over my boat on heavily loaded hardware (like 6T).

You drill and tap just as you would. It will basically ruin the drill in short order unless you use a carbide drill (pricey in 3/8" or actually Q size). But a HSS drill will do it, just don't expect that drill to be anything like on size in aluminum after that. The drill will self feed in any laminate which makes it hard to control the feed if hand held. Best to use a drill press, or flatten the lips of the drill with a grinder as you might for drilling brass. Though strong, laminate is soft so with a hand held drill motor it's very easy to move about a bit and make the hole oversize - not so good if you are going to tap it - again a drill press is your friend. When you start the tap, again because the laminate is soft, it is very easy to start the tap crooked, it will straighten itself as it goes down the hole at the expense of the threads. Once again, holding the tap in a tapping fixture or drill press, at least for the first several turns, will ensure its going straight. The tap will also dull very quickly, after several holes it will still cut the laminate but the dimensions start to go off (tighter thread) and after cutting laminate you do not want to use it for steel or aluminum again. I can get maybe 30 holes in fiberglass with a tap before the threads become too tight, less is carbon. 

I'm assuming you are tapping through the laminate. Tapping into the edge of laminate does not work well, it tends to cleave the layers.

  • Like 1

Share this post


Link to post
Share on other sites

A tip for drilling (or tapping) a straight hole, if a hand held drill motor must be used: Your eye is pretty good at aligning the bit perpendicular to the surface in the plane normal to your line of sight, but horrible in the plane parallel to your line of sight. Say you are drilling into the mast, looking down on the drill motor. Left and right your eye is pretty good at lining it up, you can get within 1 deg or less maybe. Up and down will be terrible, not uncommon to be off by 15 deg. Now what most of us try to do it look this way, look that way, try to hold the hand up and down while looking down for left and right, etc. The results are usually bad, if you drill a really deep hole you see just how bad it is. In thin material it doesn't matter that much, the hole will just be a little oval.

Get a friend to sight the other direction. In the example above, you look directly down on it, have a friend sight it from the side and keep a running commentary: "up a little, that's good, down a little..." etc.  It won't be as straight as a drill press, but much closer than trying to do it alone. You can do the same thing starting a tap.

Share this post


Link to post
Share on other sites
6 hours ago, IStream said:

A drill press is great but when I need to drill and/or tap in situ, I like these:

https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=big+gator

They make a variety of drilling and tapping guides. 

Those look pretty handy. Years ago there was a company named Portalign that sold a mini-press you could install on your drill. The chuck had to be removed so it was one of those things you needed an extra drill for. I don't know what ever happened to the idea. I've not seen one in a long, long time. 

Share this post


Link to post
Share on other sites

Yeah, I looked at one of those jiggy things for the drill (EDIT: like this one, https://www.amazon.com/General-Tools-36-37-Precision/dp/B00004T82L/ref=sr_1_25?ie=UTF8&qid=1515803697&sr=8-25&keywords=big+gator)  but there's a lot of claptrap. The Big Gators are really handy and as long as you don't let them wiggle around when starting the hole they work great. Their only fault is that they don't float.

Share this post


Link to post
Share on other sites

Boatbuilders do it differently...thier drill guides are made in the shop...many different guides for different applications.

The drill guide stock is an old SS propellor  shaft .  the shaft is  cut into pieces , drilled with the correct pilot hole and many times brought to the machine shop so that the countersink can also be machined into the guide form .

the round shape is compact ,  easy to handle , keeps the drill perpendicular to the substrate and  it has a decent surface footprint so its stable 

this is a countersunk  drill guide for mounting an anodized aluminum  genoa track , drilled and taped into aluminum 

if you have a hundred holes to drill its worthwhile making a guide.

IMG_7830.png

Share this post


Link to post
Share on other sites

Thanks for all the tips. I have taped lots of Alu. but carbon once 8 yrs ago. I will bring a few taps as I have 16 holes to tap into 3/4" thick laminate.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this