Removing stripped screws

[Merlin5]

Any ideas on the best way to remove screws with mangled heads? I watched a couple of videos and tried the elastic band trick but it didn't work. Should I get one of those double ended bits that creates a new hole and then the other end grabs and unscrews it? These screws are countersunk. M6 I think? I'm going to see if I can buy some replacement screws at Toolstation.

 

[Merlin5]

Use a dremel (other makes are available) to cut a slot into the head for a flat screwdriver?

Dremel and cutting a slot was one of the suggestions in the videos I watched. I've been meaning to buy a dremel for ages.

i used these in the past -

https://www.amazon.co.uk/CRYSTAL-CROWN-Stripped-Extractor-Hardware/dp/B09S139KWP

cheaper version from temu mind you, but they work..

Yea, that's the double ended bit also suggested in the videos and what I was thinking of buying. Don't know if Toolstation does them or does them cheap.

That looks like a prime example of just drill them out. Pick a drill thats just a little bit bigger than the threaded diameter of the ones you have already got out and then drill the head as close to the middle as you can till it just goes through. Pull apart and use pliers to take the rest of the screw out of the hole. Replace with new screws

So I understand correctly, do you mean drill clockwise as normal, then pull apart the drilled/split head and then use pliers to unscrew the threaded part of the screw?

 

[Merlin5]

Depends if you need to reuse the existing hole/thread.

Drilling out is likely the quickest option (especially with those size screws), but does mean you may need to retap the hole etc

Yep, I definitely need to reuse the holes and don't want to be messing up the holes or retapping. The screws are holding metal plates underneath a drum stool which allow the seat to mate with the legs base and allow the backrest to be attached. I'm thinking the tool that maddness suggested might possibly be the safest option.

 

[Merlin5]

Dremels are a wonderfully useful tool to have even if it rarely gets used.

I bought a cheapo brand version of Amazon for about 30 quid a few years back. Rarely gets used but absolute life saver to have when it is!

Are you able to link me to the one you got? Would you say it's as robust as a genuine dremel?

So I've been to Toolstation and they have M6 x 30mm countersunk Phillips screws in a packet of 25, but I couldnt get it to thread past about three turns into the hole. My screws look identical in thickness though. A marginal difference in the gaps between each thread perhaps but surely not enough to affect it. So I don't know what screw to get. Mine are 25mm and 20mm long and both screw in perfectly and they appear to be M6. M5 is too narrow. I'm going to try Screwfix and see if they have anything. My drum stool was made in Japan so I don't know if they're a proprietary thread, though I doubt it.

 

[Merlin5]

M6 thread pitches come in two common sizes of 0.75 and 1mm, 1mm being the most common, I suspect the new screws you bought were 1mm pitch (it may say on the packaging) , when you hold the screws together the threads should align if the do not they are definitely not the same pitch which is why you cannot screw them in, do not force them in or you will strip the threads.

Interesting. Well, fortunately I didn't buy the new M6 screws as he let me try one in Toolstation. I've been to B&Q, they've got nothing for me. And I've just been to Screwfix and he had a plastic template with lots of holes. He put my old screw (the one that fits my stool and threads all the way) into an M6 hole in his template and we could see it was slightly too thick to go through the hole. So he reckoned mine isn't an M6. I'm not sure that test is the same as the thread pitch you're talking about though. It seems as though an M6 is a smidgeon narrower and he said because of that it won't thread. I don't know, I'm going to try an independent shop now.

 

[Merlin5]

We have an independent near us and they are fantastic very helpful and always have what I am looking for, they may try 1/4-20 or 1/4-28 it may be imperial but see what they suggest.

Yes, in Screwfix he suggested mine might be imperial. As I know nothing about screws, I wouldn't have had a clue that there are things called imperial screws. . I'm going to try the independent shop in a bit. Meanwhile, I just called the drumshop where I bought the drum stool and explained the problem. He said he should be able to get me the correct screws from the company in Japan that made the stool and that they might be proprietary, he'll be able to let me know on Thursday. I have a feeling I'm going to be paying over £20 though for a few screws as opposed to the very inexpensive £4 for 25 x M6.

 

[Merlin5]

Could be https://en.wikipedia.org/wiki/List_of_screw_drives#JIS_B_1012

Would explain why the head got stripped originally if a standard philips driver was used

Good find. Hmm, if that's the case, I'll have to find an appropriate screwdriver or electric screwdriver bit. Not sure if I have the correct bit in my electric screwdriver bits box.

 

[Merlin5]

Thread pitch is how close the threads (the little spiral around the edge of the screw/bolt) are together, can also be referred to as tpi (threads per inch).

So a fine thread pitch has the threads closer together (typically 0.75mm on a "Fine" M6), whereas a coarse thread they are slightly further apart (typically 1.0mm on a "Coarse" M6). There are however other variants, e.g. 1.25mm is also a possibility.

Using the wrong thread pitch will feel like the screw is cross threading.

If you know the length of the screw e.g. 25mm you count the number of turns, and divide it, so 25mm / 20 turns = 1.25mm

Thanks. Yes, the threads on the new M6 screws that the shops had were definitely a bit closer together than on my screws. Assuming then that those were fine M6, a coarse M6 might work if I could find one. Then again, as my screws seem to be slightly thicker/wider across like maybe half a millimeter or so, I don't know if any M6 would work but I'd certainly like to find a coarse 1.0mm M6 and try it. The independent shop was closed so I'll pop over there tomorrow and see what he's got.

I don't know if I'm doing your calculation correctly. I've got two screws. 25mm long with 15 spirals and turns and 20mm with 10 spirals and turns. So that's 1.66mm and 2mm. I've done that wrong haven't I?