Announcements
New Discussions
Things to do and not to do flying a spin
by pknapp66. 10/20/19 05:25 PM
Cleaning corner castings
by extremebias. 10/18/19 04:18 PM
New England 100 2019: 30th Anniversary!!!
by brucat. 10/18/19 02:19 PM
What are EPO rudders?
by chevy43. 10/17/19 01:37 AM
NASCA 5.5 covers, where to buy?
by Damon Linkous. 10/07/19 06:05 PM
Previous Thread
Next Thread
Print Thread
Rate Thread
Hop To
Page 2 of 2 1 2
Re: Any tips for drilling out a broken beam bolt??? [Re: dacarls] #158766
10/30/08 07:30 PM
10/30/08 07:30 PM
Joined: Feb 2007
Posts: 266
UK
Cheshirecatman Offline
enthusiast
Cheshirecatman  Offline
enthusiast

Joined: Feb 2007
Posts: 266
UK
Originally Posted by dacarls
www.electroarc.com
Here is a serious guaranteed solution.
Melt your way through the bolt with an electric arc!
Note this may be good if your ship is made of stainless steel.
If fiberglass or carbon is nearby-- not so much! WHoooosh!


Also known as spark erosion. Great for brake callipers (especially sheared off bleed nipples) but as you say not for cat beam bolts.

Cheshirecatman

-- Have You Seen This? --
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252040
09/06/12 02:39 PM
09/06/12 02:39 PM
Joined: Mar 2011
Posts: 50
Hawaii
timtower Offline
journeyman
timtower  Offline
journeyman

Joined: Mar 2011
Posts: 50
Hawaii
Iím a pro at resurrecting dead threads. Anyway, hereís my problem, I broke a bunch of the 3/8Ē stainless beam bolts in my N20 taking the boat apart and now Iím screwed (no pun intended).

Attempt 1) Used a fairly small diameter titanium drill bit to drill into the first broken beam bolt. I was making good progress but then the drill bit broke. Then I proceeded to use larger diameter drill bits to continue to drill into the bolt, but the broken titanium drill bit dulled the new drill bits. I suppose if I just keep going through drill bits, Iíll get to the end eventually. Any thoughts on this problem?

Attempt 2) For the second broken beam bolt, I switched out titanium drill bits for carbide drill bits with hope that if I break another drill bit, itíll be easier to drill through a carbide drill bit. Ended up drilling through the bolt, but realized I wasnít even close to center on the bottom of the bolt. Now, I donít want to keep going up in size because Iíll chew into the fiberglass. Maybe I can use a small diamond tip dremel and wear away at the sides of the bolt?

Besides the two beam bolts that Iíve already fíd up, I have two more to go. Iím thinking with the next two, Iíll use this productÖ http://www.quikcenter.com/ Thoughts?

If worse comes to worse, my plan would be to cut out the broken beam bolts from the hull and 5200 new inserts into the hull, but that seems sketchy.

Tim


--
Sabotage
USA 302
Nacra Inter 20
https://TurnoverBnB.com
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252049
09/06/12 03:13 PM
09/06/12 03:13 PM
Joined: Sep 2002
Posts: 3,222
Roanoke Island ,N.C.
Team_Cat_Fever Offline OP
Carpal Tunnel
Team_Cat_Fever  Offline OP
Carpal Tunnel

Joined: Sep 2002
Posts: 3,222
Roanoke Island ,N.C.
All I can offer is what is in this thread. Mugrace72's advice pretty much covers your options. If it all goes to shite and you need to break the plates out just use a punch straight down on them. That is not a great option, sucks really, but it broke out on me while I was working on it so I had no choice. You do have to be able to get in there to put them back and that's a whole 'nother P.I.A.


"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252050
09/06/12 03:24 PM
09/06/12 03:24 PM
Joined: Mar 2011
Posts: 50
Hawaii
timtower Offline
journeyman
timtower  Offline
journeyman

Joined: Mar 2011
Posts: 50
Hawaii
The two bolts I was working on were the rear beam bolts. I couldn't feel a backing plate. Are they glassed straight into the hull? Also, what do the backing plates do? There's no nut on the other side of them.

Last edited by timtower; 09/06/12 03:25 PM.

--
Sabotage
USA 302
Nacra Inter 20
https://TurnoverBnB.com
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252051
09/06/12 03:37 PM
09/06/12 03:37 PM
Joined: Aug 2011
Posts: 774
Greenville SC
bacho Offline
old hand
bacho  Offline
old hand

Joined: Aug 2011
Posts: 774
Greenville SC
The bolts are threaded into a piece of SS or AL that is glassed into the deck as shown on the first page. Are you able to reach the undersides of your bolts through deck hatches?

Your drill going out the bottom of the bolt can be a problem, but you should not hit glass. If you have not already, start soaking them in a penetrant oil. Because the bolts are seized, your gonna have a really hard time using any sort of extractor until you do something to make the bolts loosen up. Heat and PB blaster normally do the trick for me, but heat is not a option for you.

I would use a cobalt drill bit, keep it REALLY lubricated and very centered and keep working up in size until your just slightly smaller than the minor diameter of the threads. Then something like a scribe can make short work of getting the threads out. Normally I do this on a mill and it works great.

Last edited by bacho; 09/06/12 03:39 PM.
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252054
09/06/12 04:00 PM
09/06/12 04:00 PM
Joined: Mar 2011
Posts: 50
Hawaii
timtower Offline
journeyman
timtower  Offline
journeyman

Joined: Mar 2011
Posts: 50
Hawaii
Thanks Bach. Convienently the aft deck plate was pulling up on that side, so I removed it and can feel the bolts from underneath. It would probably behoove me to take a picture of it, the next chance I get. I'll try the PB blaster and quik center and see if that works with the two 'fresh' bolts next time.


--
Sabotage
USA 302
Nacra Inter 20
https://TurnoverBnB.com
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252055
09/06/12 04:33 PM
09/06/12 04:33 PM
Joined: Sep 2002
Posts: 3,222
Roanoke Island ,N.C.
Team_Cat_Fever Offline OP
Carpal Tunnel
Team_Cat_Fever  Offline OP
Carpal Tunnel

Joined: Sep 2002
Posts: 3,222
Roanoke Island ,N.C.
Tim, They are aluminum which is what causes the problem .Galvanic corrosion. Use Tefgel when you re-install. If you are working at the rear you may very well want to build up that spot as a couple of boats had catastrophic hull failure due to the thickness of the laminate under the rear beam.If you are replacing the plates I'd replace it with stainless.


"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252056
09/06/12 04:58 PM
09/06/12 04:58 PM
Joined: Mar 2011
Posts: 50
Hawaii
timtower Offline
journeyman
timtower  Offline
journeyman

Joined: Mar 2011
Posts: 50
Hawaii
If it all goes south, I'm considering putting in a big backing plate and just making them thru bolts instead of screw bolts which would be an easier repair. Would you guys recommend against that? Definitely going to use Tefgel.


--
Sabotage
USA 302
Nacra Inter 20
https://TurnoverBnB.com
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252059
09/06/12 06:27 PM
09/06/12 06:27 PM
Joined: May 2006
Posts: 1,380
Kingston SE South Australia
JeffS Offline
veteran
JeffS  Offline
veteran

Joined: May 2006
Posts: 1,380
Kingston SE South Australia
My mechanic swears by freeze spray you can buy in a can. I think you are supposed to spray it on before you break off the bolt but it works by instantly shrinking the bolt a fraction thereby breaking the rust bond. If you put normal nuts on the back of the backing plates how are you planning to stop them rotating when you tighten your beam bolts in the future?


Jeff Southall
Current boats
Nacra 5.8 1703 Animal Scanning Services
Nacra 5.8 1667 Ram Raider
Nacra 18 Square
Arrow 1576
Re: Any tips for drilling out a broken beam bolt??? [Re: timtower] #252063
09/06/12 09:36 PM
09/06/12 09:36 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 12,310
South Carolina
Originally Posted by timtower
If it all goes south, I'm considering putting in a big backing plate and just making them thru bolts instead of screw bolts which would be an easier repair. Would you guys recommend against that? Definitely going to use Tefgel.


Definitely do this. There is no reason that plate needs to be laminated inside the sandwich construction of the hull. The bond only gets stronger if it's completely on the inside of the hull. Note, however, there is a bulkhead in this location and you may need to work around it. When you set the plate on the inside, make sure it is seated well in some thickened resin so it is making full contact with the fiberglass there.

Last edited by Jake; 09/06/12 09:37 PM.

Jake Kohl
Re: Any tips for drilling out a broken beam bolt??? [Re: Team_Cat_Fever] #252074
09/07/12 10:08 AM
09/07/12 10:08 AM
Joined: Jun 2001
Posts: 833
St. Louis, MO,
Mike Hill Offline
old hand
Mike Hill  Offline
old hand

Joined: Jun 2001
Posts: 833
St. Louis, MO,
He is going to have to cut a hole in that bulkhead to get to the under side of those bolts. Going to have to be a pretty good size hole to get your whole hand through there.


Mike Hill
N20 #1005
Re: Any tips for drilling out a broken beam bolt??? [Re: JeffS] #252075
09/07/12 10:11 AM
09/07/12 10:11 AM
Joined: Jun 2001
Posts: 778
Houston
carlbohannon Offline
old hand
carlbohannon  Offline
old hand

Joined: Jun 2001
Posts: 778
Houston
Originally Posted by JeffS
My mechanic swears by freeze spray you can buy in a can. I think you are supposed to spray it on before you break off the bolt but it works by instantly shrinking the bolt a fraction thereby breaking the rust bond.


The accepted method of breaking rusty bolts free is to heat them up. There is a reason for this.

The expansion or contraction of metal due to heat or cold is proportional to the original size of the hole or the bolt. Since the hole is slightly bigger than the bolt, if the bolt and the backing plate are the same material and you spray the spray the whole thing down so everything is at the same temperature, the hole will shrink more than the bolt and just clamp down on it.

In this case the bolt is SS and the plate is AL. The linear rate of expansion for AL is ~4/3 that of SS. If you chill the plate and the bolt the hole will contract 4/3 faster than the bolt and probably make things worse.

For a rusty steel nut and bolt(like on a car), using freeze spray can crush the rust and free things up. For a catamaran's beam bolts the "rust" is probably more like a super thick white goo. Chilling can compress the goo into the threads and make things worse.

Sorry




Re: Any tips for drilling out a broken beam bolt??? [Re: Mike Hill] #252083
09/07/12 01:24 PM
09/07/12 01:24 PM
Joined: Mar 2011
Posts: 50
Hawaii
timtower Offline
journeyman
timtower  Offline
journeyman

Joined: Mar 2011
Posts: 50
Hawaii
Actually, the rear beam bolts on my boat are aft of the first bulkhead, so I was able to at least feel them by taking off the aft deck plate. Not sure if they changed the build on later boats though.


--
Sabotage
USA 302
Nacra Inter 20
https://TurnoverBnB.com
Page 2 of 2 1 2

Moderated by  Damon Linkous 

Search

Who's Online Now
1 registered members (cyberspeed), 35 guests, and 72 spiders.
Key: Admin, Global Mod, Mod
Newest Members
extremebias, Isotope776, stewartgood, Trampolines, certid
7970 Registered Users
Top Posters(30 Days)
brucat 2
Forum Statistics
Forums26
Topics22,368
Posts266,940
Members7,970
Most Online1,650
Sep 10th, 2019
--Advertisement--
Powered by UBB.threads™ PHP Forum Software 7.7.1