Seized Screw

[goeasy123]

I just bagged a used Hydrovane that I'm refurbing. A lot of the screws were 'welded' in with Al Oxide where there is an interface between Al casting and SS screws. All the grub screws that retain the plastic shaft bearings are OK, but the 2 that retain the top shaft are seized. The other clamping screws I've had to drill out and I'm going to Hellicoil the internal threads. Two questions:

1. Any ideas on getting these 2 screws out? I've soaked them in easing fluid over night. I don't want use heat because of the plastic bearing.
2. What's the best way to stop SS screws seizing the the Al casting? The worst cases are where the bolts go through clearance holes.

 

[Rappey]

Sometimes you can drill a small hole through the centre of the seized bolt and then they undo ! Not sure quite how this works but it can..
The metals fuse together so penetrating fluid seems to have zero effect. I would also try to drill out the screws using the correct size tapping drill (proving you can drill square to the screw) then retap thread and it will be the same size?
Duralc is a good product to stop ally and stainless galvanically corroding together.

 

[oldharry]

Sometimes you can drill a small hole through the centre of the seized bolt and then they undo ! Not sure quite how this works but it can..
The metals fuse together so penetrating fluid seems to have zero effect. I would also try to drill out the screws using the correct size tapping drill (proving you can drill square to the screw) then retap thread and it will be the same size?
Duralc is a good product to stop ally and stainless galvanically corroding together.

I've found this too. After drilling screws release quite easily - sometimes! I reckon its the very localised heat of the drill, exactly where its needed near the bottom of the thread and the vibration that breaks the grip. Probably more the latter.

 

[goeasy123]

Sometimes you can drill a small hole through the centre of the seized bolt and then they undo ! Not sure quite how this works but it can..
The metals fuse together so penetrating fluid seems to have zero effect. I would also try to drill out the screws using the correct size tapping drill (proving you can drill square to the screw) then retap thread and it will be the same size?
Duralc is a good product to stop ally and stainless galvanically corroding together.

I'm not sure about Duralc. I sounds like something you would use on a permanent joint. I want something the stops parts from seizing togther that you want to take apart on a regular basis.

 

[Hacker]

Tef-gel is your other option to help prevent the corrosion

 

[Concerto]

Apply heat from a MIG welder to the screw head should break the seal.

 

[goeasy123]

Apply heat from a MIG welder to the screw head should break the seal.

It's a short grub screw in a deep recess bearing on a plastic bearing I don't want to risk destroying.

 

[LittleSister]

Can you heat up whatever the shaft and grub screws are in with something that isn't going to overheat the plastic - hair dryer, hot air gun gun on lower setting, or repeated applications of boiling water, etc.?

 

[Daydream believer]

You can buy left hand drill bits & drill out. With a battery drill in reverse, at some point in the drilling process the screw should release.
The heat of the drilling helps, but do not go so slow that you harden the stainless screw.

 

[Daydream believer]

I'm not sure about Duralc. I sounds like something you would use on a permanent joint. I want something the stops parts from seizing togther that you want to take apart on a regular basis.

The best way to do that is to actually take it apart on a regular basis & not leave i.

 

[burgundyben]

Use alum powder to dissolve the screw. Various youtube clips on how.

 

[PCUK]

Duralac is a sort of grease that smells like pig sh*t but won't harden like an adhesive! Not that this is any help at the moment. I'm interested in the Alum powder though.

 

[burgundyben]

Watch

 

[burgundyben]

Or here

 

[RichardS]

Duralac is a sort of grease that smells like pig sh*t but won't harden like an adhesive! Not that this is any help at the moment. I'm interested in the Alum powder though.

If access is reasonable, the reverse HSS drill bits mentioned above work for me.

Richard

 

[goeasy123]

Well... that was a pretty productive thread!! Some good ideas to try. Thanks everyone

 

[Roberto]

2. What's the best way to stop SS screws seizing the the Al casting? The worst cases are where the bolts go through clearance holes.

I use lanolin, or derivative Lanocote, in all the stainless bolts of my aluminium made Windpilot, works very well.
Useful for turnbuckles/rigging screws as well. It sort of solidifies and cannot be washed away.

 

[steve66]

Heat shock it. Get the area as hot as you can then cool immediately. I use carb cleaner to cool. May take a couple of cycles but the will work

 

[Pye_End]

I'm not sure about Duralc. I sounds like something you would use on a permanent joint. I want something the stops parts from seizing togther that you want to take apart on a regular basis.

Duralac is considerably less 'permanent' than ali to stainless seizing.

 

[Beneteau381]

You can buy left hand drill bits & drill out. With a battery drill in reverse, at some point in the drilling process the screw should release.
The heat of the drilling helps, but do not go so slow that you harden the stainless screw.

Slow and heavy with plenty of lube for SS! Fast is what work hardens