Removing self tapping screws

[Davidkinton]

I need to remove some self tapping screws which have been used to secure Perspex Windows to a grp cabin top. I tried with a screwdriver but they are solid, so next alternative is to drill off the heads and then remove the Perspex and then try and mole grip the rest of the screw out. Any other suggestions would be welcome.

 

[Kelpie]

Have you got an impact driver?

 

[Pye_End]

I find a good old fashioned brace as good a way as any for getting plenty of pressure onto the screw head, and a loads of leverage. If the screw will not budge, it will almost certainly snap the head off. No idea as regards lubricant or heat with perspex, but expect somebody will.

 

[Lon nan Gruagach]

I need to remove some self tapping screws which have been used to secure Perspex Windows to a grp cabin top. I tried with a screwdriver but they are solid, so next alternative is to drill off the heads and then remove the Perspex and then try and mole grip the rest of the screw out. Any other suggestions would be welcome.

I know its going to put quite a hole in the GRP but

 

[TQA]

Using an impact driver will almost certainly result in cracked perspex. Use an old fashioned brace with the correct size of screwdriver bit.

But I suspect you will be driven to drill off the heads and use a hollow bit to get the shaft of the screw out. Fill the holes with JB weld and redrill Lightly grease the new screws before fitting.

 

[Woodlouse]

A big screwdriver with a square shank that you can wrap a spanner round. If that doesn't shift it then likely nothing will.

 

[nemodreams]

Normal self taps ar extremely hard - you wont easily drill the heads off. If the heads are recessed into allloy countersinks - they can be a pig to remove without damage to the alloy frame.

As I often use on Seagull outboards - get a new cordless drill type 'good quality' flat bit - and mount it in a 1/4 AF socket. You can then use a socket wrench etc to give pressure and twist.
If you have a good slot - you should be able to shear off the head - they are hard but very brittle ! If the slot rides - deepen with a demel.

Unfortunately the gas torch is not an option here

 

[Scotty_Tradewind]

With a very good fitting screwdriver blade which has a handle you can hammer, I would try sharp taps on the head using a small hammer.
Then with a lot of weight pressed down on the driver, I would try and 'tease' the screw a degree or so tighter, before trying to loosen.

I have a small electric impact driver and if the screw head were Posidrive or Philips I'd use the

appropriate Wera bit and with a lot of pressure down and try and give it short pulses to loosen.

I would not use an electric screwdriver with straight slot headed screws.

Have you considered grinding the heads down with something like a Dremel tool? (use goggles)

Perhaps if you masked around the head this would allow you to get the heads off without marking the Perspex ???

Good luck,

S.

 

[RichardS]

Normal self taps ar extremely hard - you wont easily drill the heads off. If the heads are recessed into allloy countersinks - they can be a pig to remove without damage to the alloy frame.

I don't think they'll be that hard providing you use a good quality cobalt bit or similar. I've always found cross-head screws very easy to drill out because you already have a guide hole in the perfect position. Just choose a drill bit which is the same size as the shank of the self-tapper and you won't damage the countersink.

Should take a couple of minutes each.

Richard

 

[laika]

If none of the other excellent suggestions here work and it comes to drilling out, plenty of good advice on drilling screws was offered to me in this thread:
http://www.ybw.com/forums/showthread.php?429465-Drilling-out-broken-screws


But going a little off topic...

I know its going to put quite a hole in the GRP but

As I recently discovered (Some forumites will have seen me sporting the pirate look recently) dentists use the exact same techniques for dealing with recalcitrant screws on old implants as we do in DIY (only on a much smaller scale (thankfully, as I wouldn't fancy a dremmel in my mouth...))

 

[macd]

If you can beg or borrow a battery a drill with a 'rattle' facility, they may come out quite easily. I have a little Makita 9V job which shifts things amazingly well. It'll put a lot less stress on the surroundings than an impact driver.

 

[lw395]

Left handed drill bits often work on 'abused' pozi or philips screws.
Heating the screwdriver with a gas flame is another trick that works if the screws have been threadlocked, likely to work on GRP too?

A brace and bit is good for pressure and leverage.

Good Luck!

 

[LadyInBed]

I need to remove some self tapping screws which have been used to secure Perspex Windows to a grp cabin top. I tried with a screwdriver but they are solid, so next alternative is to drill off the heads and then remove the Perspex and then try and mole grip the rest of the screw out. Any other suggestions would be welcome.

X head or Slotted?
Countersunk, Pan or Dome head?
Is the perspex to be sacrificed or do you want to reclaim it?

The answers will give more direction to the approach
ie - cut / chisel off perspex round the screw to get a molegrip on it.
- Cut a slot in X head
- Apply heat

 

[ostell]

Soldering iron on the screw head to warm up and expand and break any locking seal

 

[colind3782]

Drill and an EZ out or similar?

 

[ghostlymoron]

Sounds like a good plan but I would use Stillsons not Moles as they tighten up as you apply force whereas Moles tend to slip off.

I need to remove some self tapping screws which have been used to secure Perspex Windows to a grp cabin top. I tried with a screwdriver but they are solid, so next alternative is to drill off the heads and then remove the Perspex and then try and mole grip the rest of the screw out. Any other suggestions would be welcome.

 

[davidej]

can you get stillsons small enough for a job like this?

I would be inclined to try something like this - probably better than an easy-out for this type of job

http://www.ebay.co.uk/itm/4PCS-Scre...384293?hash=item21009066e5:g:adwAAOSwyQtVyuWU

 

[ghostlymoron]

You can certainly get 8" stillsons.

 

[rogerthebodger]

This kind of stud extractor will help if there is any of the screw protruding.

http://www.lasertools.co.uk/item.aspx?code=4393

http://www.toolstop.co.uk/sealey-ak718-impact-stud-extractor-6-12mm-1-2sq-drive-p55631

Or even a small drill chuck may also do the job.

 

[Poignard]

Soldering iron on the screw head to warm up and expand and break any locking seal