Removing stubborn screw

[Gliderman8]

I am at a loss and hoping for some help here. As you can see I have a round steel plate that holds an oil seal and bearing in place. It has four countersunk screws. When the screws were installed in 1963 they were "punched" so they would not turn out.
At this point I have managed to get three of them out.... isn't that they way it always is?
I just cannot get the fourth screw to budge.
I've taken a dremmel tool and relieved the punched area.
I've heated the area around the screw.
I've let it sit for days with penetrating oil
All of the above has not worked.
The screw head is really misshaped from the screw driver twisting out. Using an easy-out does not seem like a good option since the likelihood of drilling a hole dead center for the easy-out seems slim.
The only option I can see is to try and grind the head off and then may get a vise grip on the thread and twist it out if I'm lucky.
ANY OTHER IDEAS that you guys have?

 

[equiprx]

Impact screw driver.

 

[AN5Sprite]

My favorite impact/drill set:

https://www.wholesalepowertools.com/makita-lct200w-compact-lithium-2-tool-combo-kit-drill?gclid=CLXUwNyuu7UCFYje4AodZm0ACw

Worth every penny.

 

[Gliderman8]

I'll give the impact a try tomorrow and let you know. Thanks!

 

[David_Doan]

If the impact doesn't work - and don't be afraid to hold it on for a long time, I did the same thing today, all the hammering will help it break loose. the next option is to drill it out. Center-punch it and drill into the screw starting small - 1/8 ish - and work up until the head fall off, then hopefully the shell of the screw that is left will thread out. Otherwise keep going bigger in until the remainder of the screw falls apart. then run a tap in to clean it out.

 

[TomMull]

If the impact doesn't work - and don't be afraid to hold it on for a long time, I did the same thing today, all the hammering will help it break loose. the next option is to drill it out. Center-punch it and drill into the screw starting small - 1/8 ish - and work up until the head fall off, then hopefully the shell of the screw that is left will thread out. Otherwise keep going bigger in until the remainder of the screw falls apart. then run a tap in to clean it out.

Good advice but careful not to break the little drills. I try to start with something bigger than 1/8, the biggest I can get to work. If you need to go really small, try the double ended 1/8th drills which are very short. Once you get the head off you can usually pull off the flange and get the rest with grips. Tom

 

[Gliderman8]

Thanks again guys for the help.

 

[TR3driver]

Probably too late now, but my suggestion would be a hand impact tool, like

It seems like the stout hammer blow directed inward seems to help loosen the screw, as well as help keep the bit from camming out.

If the slot is too badly damaged, you can try cutting a new one with the Dremel and an abrasive cut-off blade. If that doesn't work, cut a few more slots and collapse the head until you can get the ring off, then cut a new slot deeper and try again with the impact tool.

 

[Gliderman8]

Randall- I have that exact tool. The only problem is that the engine case is made out of cast aluminum and I was afraid if I hit it too hard I might crack the engine case. If the case cracks, it's good bye engine

Here's the engine....

 

[JPSmit]

can you determine whether the head is still peened? or the threads binding in the aluminum? If peening, obviously will need to relieve it more, but, if threads, I have had good luck with heating, then splash water to "jolt" then heat again, then touch the screw with wax to melt it down the side.

 

[Gliderman8]

Good suggestions JP.... I did use my dremel tool to relieve the peened area. It looks like I have gotten down all the way to take the pressure off but you could be right. MY guess is that it's not the thread that are binding since the other three came out without much ado.
Tomorrow I'm going to try an electric impact screwdriver; if no luck then see if I can drill the head a little and see if that helps.
I did heat the.... you know what out of it and it didn't phase it. I think the aluminum is dissipating the heat rapidly.... just my guess.
Will give the wax a try... good suggestion!

 

[TR3driver]

Well, obviously you have to exercise some discretion; but I used it all the time on my motorcycles and never broke anything.

Only other suggestion I have (that hasn't been already covered) is to use the Dremel to grind a depression in the center, then drill as close to on-center as you can. Keep stepping up in drill size by small increments until the threads show on one side, then try to pick out the remains of the bolt with a dental pick.

But try JP's wax trick first.

 

[Gliderman8]

Can't believe it... I borrowed an electric impact screwdriver and much to my amazement, it twisted out. I didn't think it would work and I was making plans to drill it out as you all suggested. I did have a candle in my pocket but there was no need for it.
When you look at the photos you can see how deep the head was peened into the countersunk hole... no wonder it was hard to turn.
Thanks to everyone for their wonderful suggestions... what a great resource the BCF is!!!

 

[70herald]

Oh great now you've gone and given me a reason to justify buying another tool!

 

[Gliderman8]

Oh great now you've gone and given me a reason to justify buying another tool!

Just do what I did.... borrow it from a friend

 

[Lukens]

Glad you saved it.
Gotta ask: what kind of engine?

 

[Basil]

It is always one screw, isn't it? Some sort of law of nature it seems. When I replaced the brake rotors on my Santa Fe recently it was ten same deal. Of the total time spent changing out four rotors, better than half that time was spent on ONE small screw!

 

[Gliderman8]

You are right Bas.... The first three came out one, two, three and then the brick wall
Isn't it always that way?
Lukens... The engine is from my 1963 Lambretta TV175. It was smoking pretty bad since the drive side seal was letting transmission fluid by. I think it's about time to change out the seals and bearings as they are the original seals and bearings and they are almost old enough to collect social security!

175CC
4-speed manual shift
Top Speed about 65mph

 

[aeronca65t]

Left handed drill bit.

Works better than anything else I have for problems like this (I have the impact driver shown above).

Use a drill bit about 1/2 or 2/3 the size of the screw you're trying to get out.

Usually, I drill in a little bit and all the vibrations and torque unwinds the screw.

In fact, I have gotten fairly good at sharpening drill bits "backwards" on a normal drill bit. The "twist" is wrong, but for a shallow hole, it doesn't really matter.

 

[Gliderman8]

Thanks Nial... I might put that info to good use very soon as I found one of the studs on the engine case was broken off inside the hole.