Stuck boxlock cover plate screw FIXED

[yorgi]

I have an old 1960's Spanish Laurona boxlock that's worth nothing but holds a lot of sentimental value to me. Decided to do a complete disassembly followed by a thorough cleaning and lubrication, want to start with removing the cover plate....problems already.

It might seem that I used the wrong screwdriver but believe me I didn't... Have busted/warped two slot heads as well as one repurposed filed-to-fit slot screwdriver, it ain't moving. In the process, I've managed to bugger the screw but at this point I'm not that worried about that. I can always go back and file the damage while widening and deepening the slot for any future removal.

Have been spraying it with penetrating oil for the last two days yet nothing has budged, the fit is just too great for it to penetrate the threads. Even tried tapping it with a hammer via a fitted screwdriver in the slot, no go... Have not introduced heat in the equation yet.

Will heating the perimeter of the screw with Mapp gas (not red just very hot) damage the plate. Will the heating help me break the bond? Maybe a small end-mill on my drill press to deepen and widen the slot in position? Then use a thicker, deeper screwdriver? I find that the original slot is way too thin and way too shallow to provide any bite.

Sorry for the bad cellphone pic..

Edited to add: Screw slot as mentioned is very narrow, shallow and lowest point is not parallel to the plate, To add insult to injury, the walls of the slot are not parallel to each other but rather angle inwards, wider at the top than the bottom.

 

[hunter5425]

Tap the screw driver down smartly while turning, this will often break them loose, but with the screw buggered this is going to be much more difficult. If or when you get the screw out lightly hammer the top of the screw to displace the metal back then get a slot head file and deepen and clean out the slot, that way some of the engraving will survive.

 

[fingers284]

You mention having a mill machine. I have used mine in a similar situation to remove a stubborn screw. I clamp the piece with the screw onto the mill table so it is immovable , now chuck up a screw driver blade ( the best and most robust one that fits the slot that you have) and use the quill to drop/ hold the blade firmly in the screw slot. Hold steady down-pressure with the quill ( it will be much more amplified than what you can with a hand-held screwdriver), now turn the quill with a wrench or bar or pipe wrench. This will either break the screw loose or break the most robust driver you have LOL.

 

[yorgi]

Tap the screw driver down smartly while turning, this will often break them loose, but with the screw buggered this is going to be much more difficult. If or when you get the screw out lightly hammer the top of the screw to displace the metal back then get a slot head file and deepen and clean out the slot, that way some of the engraving will survive.

Thanks for the tip! Would heat help?

You mention having a mill machine. I have used mine in a similar situation to remove a stubborn screw. I clamp the piece with the screw onto the mill table so it is immovable , now chuck up a screw driver blade ( the best and most robust one that fits the slot that you have) and use the quill to drop/ hold the blade firmly in the screw slot. Hold steady down-pressure with the quill ( it will be much more amplified than what you can with a hand-held screwdriver), now turn the quill with a wrench or bar or pipe wrench. This will either break the screw loose or break the most robust driver you have LOL.

Sorry, "mispoke"... I don't have a mill machine, just a plain old drill press. I should have said an end mill "bit" , chucked into a normal drill press. Any machinists on this board will surely get a chuckle from this..

 

[silver 55]

The drill press might work. You could also consider an impact driver.

 

[sean69]

file the mangled bits off now then make a small square graver to chase the bottom and sides of the screw slot (square them up) then smack it with an impact driver.

 

[buzzmagoo]

Have you tryed a impact driver ? A couple of good wacks should Loosen her up . Cambodian tire should have them , if the slot head bit doesn't fit grind it to size .if there are no spring metals attached you could heat it up in a toaster Oven a couple of times( heat cycles) not as agressive as a direct flame then shoot some loose nut juice on it the heat will draw it in . If all else fails drill it out ,start out under size if Accessible from the other side you could try there first to try and save the screw head . To reproduce the screw a Lathe will handy . No easy answers ,Patience and a little luck will get you threw

 

[yorgi]

It's out! Thank you to everyone who took the time to reply. I used all your combined knowledge and associated tips to get somebody else to remove it!
My buddy is an autobody man and this was his day off. The rest of the guys at the shop were somewhat perplexed when he showed up with a shotgun receiver LOL... Thankfully, he's a hunter and he's known to make visits with his various projects.

At the shop, he picked the absolute closest Snap-On slot bit that fit the screwhead. Tapped it a few times (well maybe more than a few...) and then used the torch on the head for maybe two seconds. This was followed by another tapping session and the screw came right off with minimal effort.

Close inspection (sorry for pic) revealed that the outside perimeter of the screw head, as well as the threads were pristine! The part that caused me all the grief was the underside of the head, specifically where the underside of the head met the receiver "shelf". Countless years of neglect and non-removal caused this donut-shaped surface to rust and bind the screw. #2 Robertson bit was included for comparison. Now, I will take my time and try to somehow mitigate the buggered head, as best I can, while tidying-up the slot. Lesson learned, I will dab the underside with a light coating of anti-seize before final installation.