Cutting slots in screws

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Nocturnal13

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Apr 18, 2017
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Not sure where to post this but I was wondering what thickness dremel discs to use if you want to cut a slot in a stripped screw. I've had to do it once but it pretty much almost grinded the whole screw away so I'm sure the disc was way too thick.

Any feedback would ve highly appreciated.
 
I guess the size of the disc it depends on the size of the screw.

But as a rule I use a reversible drill press with a "backwards" bit so the cutting energy also tries to unwind the part. The press is important so that the bit won't skate off the head and mar other parts.
 
Less than the diameter of the thread size. ~1/4 of the diameter of the screw head. Anything more and you run the risk of the head breaking when you try to turn.
Alternatively you can try a cheap dispodable torx bit that is slightly too large and gently hammer it into place and turn IF it isn't locktited shut.
 
On small screws use the thin brown discs that are not reinforced. Don't use the thick heavy duty grey/black ones that are reinforced. They are too thick for small screws.

Edit- Use the kind on the right and not the kind on the left.

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Using a Dremel is a sure way to screw things up. Dremel wheels are for cutting off, and are neither square or rigid.

Screw slots should be cut with a saw, or a file, or in a mill. Ideally they are hand cut once the screws are "indexed". You do this by using an over tall head to fit the screw, and then mark the head as to how low it should be cut and the direction of the slot. You can get files and saw blades in a variety of thicknesses from Brownell's. Note, it is very important to be square when doing this cutting, as good screws have parallel sides and are cut on center. If you're off there's a good chance the screw head will fail under stress.

If you use a mill you can either put the screw into a jig and hold it at 90 degrees to the cutter or use a 90 degree head and cut the slot normally. Screws are not normally hardened, so you can cut fairly slow.

If it's a screw in a hole and I'm trying to get it out I use an "E Z Out" if possible. If I have to cut a slot I prefer to drill a series of small holes and then clean the slot with a file or chisel. Don't forget to put some penetrating oil on the screw before, and apply a little heat if you know they used a thread locker (a soldering iron is good for this). Once you have the screwdriver in the slot tap gently on the handle as you try to turn the screw and that helps break them loose.

It should be noted that I always try NOT to make a mark on the metal surrounding the screw hole. Another reason why the Dremel is a bad idea.
 
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He is trying to remove a screw with a stripped head not make a new screw.

Also grind down the abrasive disc to the optimum diameter to not damage anything but the screw head. You may need several disc as they are fragile. Wear safety glasses.
 
Thanks guys. Quite a few things here that will help me a lot and some that I never even thought about.
 
Again, the problem with using a disc to cut into a screw is that it will not give you a good cut. If the screw is 0.3" diameter you need a disc about the same diameter, or basically the size of the shaft on the Dremel. A larger disc means you're going to cut into the surrounding material. A disc also means that the slot you cut will probably have walls that are not parallel, so the force exerted when you try to back out the screw will actually push the sides of the head away and down, which is why those screws strip in the first place. And last, unless your screwdriver has a curved blade, you can never get to the bottom of the slot and are more likely to be off center, which again leads to striping, or the screwdriver jumping out of the slot and making a nice mark on the material.

If you can't do anything else, go get the darn thing EDM'd and be done with it.

I've fixed, or tried to fix, too many buggered screws to be bothered anymore. It's usually a case of making the problem worse when people who don't have the right tools get a visit from the good idea fairy.
 
eisman said:
Again, the problem with using a disc to cut into a screw is that it will not give you a good cut. If the screw is 0.3" diameter you need a disc about the same diameter, or basically the size of the shaft on the Dremel. A larger disc means you're going to cut into the surrounding material. A disc also means that the slot you cut will probably have walls that are not parallel, so the force exerted when you try to back out the screw will actually push the sides of the head away and down, which is why those screws strip in the first place. And last, unless your screwdriver has a curved blade, you can never get to the bottom of the slot and are more likely to be off center, which again leads to striping, or the screwdriver jumping out of the slot and making a nice mark on the material.

If you can't do anything else, go get the darn thing EDM'd and be done with it.

I've fixed, or tried to fix, too many buggered screws to be bothered anymore. It's usually a case of making the problem worse when people who don't have the right tools get a visit from the good idea fairy.
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This may be a stupid question but what's EDM?
 
No doubt, using a Dremel to cut a slot in a screw is a half assed. I guess it depends if the knife cost $10, $100, or $1000.

I wish there was an EDM machine within 100 miles of me. My life would be easier.
 
Nocturnal13 said:
This may be a stupid question but what's EDM?
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Electrical Discharge Machining. Kind of an expensive method of removing a screw for the average person. We have EDMs where I work and our shop would probably charge you anywhere from $50 to $100 to do it.
 
The problem with EZ out is that I don't live in the US so getting replacement screws is not always easy.Especially with brands that doesn't have the best customer service. That's why I was wondering about the best way to remove the screw and being able to use it again if finding a replacement is not possible.
 
Nocturnal13 said:
The problem with EZ out is that I don't live in the US so getting replacement screws is not always easy.Especially with brands that doesn't have the best customer service. That's why I was wondering about the best way to remove the screw and being able to use it again if finding a replacement is not possible.
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Reusing a damaged screw that you've brute forced out of the part is a recipe for disaster.

Just because you got it out once doesn't mean it'll work twice never mind not being able to properly secure it when re-installed.
 
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Danke42 said:
Reusing a damaged screw that you've brute forced out of the part is a recipe for disaster.

Just because you got it out once doesn't mean it'll work twice never mind not being able to properly secure it when re-installed.
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Would it then be possible to buy a screw at a hardware shop/screw factory etc that would fit?
 
If the screw is not "normal" hardware, like gun screws, there are places to get them. It's pretty important to know the thread, as trying to stuff something from Home Depot into a 8/56 threaded hole is going to bugger the project up to where it's getting expensive. The number of scope mounting holes I've rescued from do it yourselfers could pay for a used Porsche. Add in Metric, Machine, and Fine threads and it gets fun.

Even if you never use it, get a catalog from Brownell's.

You can build your own EDM. Look on youtube.
 
eisman said:
Using a Dremel is a sure way to screw things up. Dremel wheels are for cutting off, and are neither square or rigid.
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Over the last forty years I have cut conservatively 50 slots or more this way in small hardened allen key screws as well as torx to create screw driver slots to remove the screws. Never a problem.
One has to get a two handed grip on the Dremel. Practice a little if there is any question. One finds out pretty fast how to guide it.
One can stack two discs to get a wider slot in a larger screw head if needed.
Applying a lot of downward force on the screw driver helps.
For torx I have other methods but I have used the thin Dremel cut off wheels.

PS: people here keep telling me I can't cut nail nicks with the dremel (or the diamond wheels of the same ilk) . . .
and yet . . . oh look here's one ;) :rolleyes: . . . as if by magic.
IMG_5185.jpg
 
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