unbolting a plate bedded with 5200

DDW

Super Anarchist
6,251
985
5200 creeps. Get a wedge started under one corner. Every hour or so give another tap in. If you just pry it off you may get the gel coat with it. 

 

danstanford

Anarchist
574
132
Lake Ontario
I would loosen the nuts from below then use a jamb nut under them to lock them together and then twist the bottom nut to put torque on the machine screw. Once the screws are loose and removed I would move on to getting the fishing line under the plate to slice through the sealant. 

 

SloopJonB

Super Anarchist
65,894
10,945
Great Wet North
What's a B&B ??

image.jpeg

 

SloopJonB

Super Anarchist
65,894
10,945
Great Wet North
Oh wait, I just Googled M18 impact driver. This is a power tool, I thought you guys meant the handheld one you hit with a hammer. Did you mean one of these power tools use for driving bolts into cement? 
I recently acquired one of these.

28a149a1df0f8958b29605d401685ff3980d0d1c_66001030_1_66001030_TOURNEVIS_C.jpg


I don't know how I got deck hardware unbolted before - this zips off nuts with no-one holding the other end and it doesn't even disturb cured sealant around the shank..

 

NaClH20

Super ciliary
If it is actually 5200 yer in for a treat. IME heat is your friend [Sea story!  Was once working on a large-ish wood schooner.  Owner/builder loved bedding everything in 5200… not only hardware, but planks over deadwood, backing blocks, frame ends, etc.  Went through cases of the stuff. Installing the bronze hawse pipes, the plan was to put the cast pipe in from the outside, then the inner trim ring, then cut flush and grind the inner edge.  Outer piece installed, bedded, screwed in.  Inner piece installed and screwed in, then no tool could be found to fit in to make the flush cut.  Getting the hawsepipes back out involved blow torch, sledge hammer and a solid afternoon].  As recommended above, I like heat, time, and a brace and bit (the b&b referenced earlier), as impact drivers have a habit of damaging stuff quickly when used in circumstances with unknown variables.  I have a large flat head driver made for a b&b that I use for exactly such a bolt purchased years ago at an used tool store.  Concentrate heat on the bolt, either with a solder iron or very small flame.  Turn, gently, with the brace until it lets go.  If it doesn’t work, heat more until it does.  Same idea prying the plate off… force will only find the weakest link, which is usually the substrate (wood fibers/gelcoat layer) rather than the glue bond.  Careful use of a heat gun to warm the entire plate, along with prying with a thin scraper should do the trick.  I haven’t found fishing line to work, but maybe that just me and the things I try to get up are usually in awkward locations and require a degree of creativity.
 

Good luck!

Edit:  good substitute for a brace is a big screwdriver that has part of the shank milled to six sides, and a wrench.  A screwdriver that would fit the slot should be available at any hardware store… it’s the width rather than the length that’s important.  I’ve got a Lowe’s brand one within arms reach right now.  At worst get a cheap one and grind the tip down until it fits

 
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longy

Overlord of Anarchy
6,266
884
San Diego
I would loosen the nuts from below then use a jamb nut under them to lock them together and then twist the bottom nut to put torque on the machine screw. Once the screws are loose and removed I would move on to getting the fishing line under the plate to slice through the sealant. 
^^^^^^^^^^^^Double nut & lock the bolt. Apply large breaker bar - they will rotate free of the caulk with no damage to bolts. 

 

Zonker

Super Anarchist
9,122
5,034
Canada
I recently acquired one of these.
When I was doing cancer treatments and not in the best of shape I got a Rigid 1/2" impact gun just for changing the tires from summer to winter. Made this job a breeze.

Yes I use what would be called a creme brulle torch too. Very focused flame. Like right on the head of the fastener. Damp rags on the underside to keep the laminate cool

+1 to wedges and patience. I would also suggest the thin autobody type plastic tools used for prying trim off doors etc. Find them at your local auto parts store. These sort of things. Won't scrape the deck but sturdy and thin. 

https://www.napacanada.com/en/p/MXC5751197

 

weightless

Super Anarchist
5,607
581
For starting on cutting the caulk line sometimes it can be helpful to have both a stiff straight edge paint scraper and a sharpened, thin, flexible putty knife. Put some masking tape down around the work area. With the scraper's bevel edge flat on the deck work it's blade under under the edge of the plate. Then the pry up the edge a little. Slide the sharp putty knife into the gap that opened up between plate and deck and work it around to get a bit of a slice going in the caulk. Pry more, go slowly, use increasingly large wedge like items to maintain some pressure. 

Putty knives come with a squared blade. For this use sharpen them so they have an edge like a straight scraper.

 

SloopJonB

Super Anarchist
65,894
10,945
Great Wet North
When I was doing cancer treatments and not in the best of shape I got a Rigid 1/2" impact gun just for changing the tires from summer to winter. Made this job a breeze.
I just got my second 1/2" air impact for exactly that - and screwing lag bolts on construction projects.

It replaces the first one that finally died after 35 or so years.

I would never use it in the boat though - the little cordless Bosch is a ballet dancer next to the 600 Ft/Lbs of the air Hulk Hogan.

 

Zonker

Super Anarchist
9,122
5,034
Canada
The 18V Rigid one I have is good for (surprisingly) 450 ft.lb. It has 3 range settings for torque. Lug nuts are #1 - the lowest setting. 

I figure the higher settings will be good if I ever need a bit of extra torque to remove suspension components on a car.

 

sailman

Super Anarchist
8,290
416
Portsmouth, RI
Which do you think it better, Antibond 2015 or Marine Formula Debond ?   How long did you have to let the Antibond sit before it worked? A 1.5 oz spray bottle is about $50!
The anti bond works instantly once it gets under the 5200.  Use a sharp scrapper so you get right under it and it peels right up.

 

Quickstep192

Anarchist
678
118
Chesapeake
I have really screwed this up before, hammering from below when it gave.  Went topside to revel in my accomplishment when I realized I had torn off the top skin and the gelcoat...  I hate 5200. 
I've done that same thing with a stanchion base bedded in 4200. I was prying with a putty knife and when the base started to move, I got greedy and pried too hard and some gelcoat came off. And that was with 4200. 

 

George Dewey

Super Anarchist
2,071
118
Charleston, SC
I've done that same thing with a stanchion base bedded in 4200. I was prying with a putty knife and when the base started to move, I got greedy and pried too hard and some gelcoat came off. And that was with 4200. 
When I put it back together, given there are these 4 very large bolts holding it together, I presume I won't need any 5200 or 4200?  Just some silka or Life Caulk maybe? Even if it leaks, it's going to leak into the anchor locker. 

 
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