What does <drilling out screws> mean?

[Andreas Thaler]

Screws that cannot be removed are one of the challenges of camera repairs; we've discussed this several times before.

One method involves drilling out screws. What exactly does that mean?

Drilling into the screw head so that a counter-rotating bit can be inserted to extract the screw?

Or drilling with a larger diameter that completely removes the screw and its threads and enlarges the hole?

I've rarely had success with drilling into screw heads; the drill never got deeper than the bottom of the screw head.

 

[Meinrad]

Hoi Andreas, i think it can mean both ways. I have practiced it only with bigger screws (M3, M4 - motorycle)
Most of the time it just helped to drill a smaller hole in the screw and the tension of the head got smaller, maybe because of the heat too. Second way is theoretically ok but the art is centering precisely the drill and also having the right diameter.

 

[Meinrad]

P.s. i think in the german aphog forum there was a longer discussion about the different methods.
ah i have found https://forum.aphog.com/index.php?t...-ihr-hier-tun-ausgefranzte-schraube/&pageNo=1

 

[forest bagger]

I often encounter these nearly impossible-to-remove screws. If I can avoid drilling them out, I leave them alone and loosen other screws.

 

[Don_ih]

Screws tend to now be a harder material than what they're in, which makes drilling them out difficult. The drill wants to drill beside the screw instead of into it. If a screw has its drive stripped out, you can sometimes cut a standard slot into the head using a rotary tool and a very small cutting disc. I try to do that instead of drilling into the screw. If I have to drill into the screw, it sometimes can be better to just try to drill the head away so it detaches whatever the screw is holding, then you may be lucky and have enough of the remaining screw to grab with pliers and twist out. Often, the screw itself (without the head) comes out easily.

Try heat and impact before trying to drill. It's a last resort. Using the correct drive is most important.

 

[hardly any color]

[…] Using the correct drive is most important.

True. Hence a set of JIS screwdrivers is a must

 

[Ian C]

“Drilling out screws” is a broad term. It happens when a screw cannot be removed in the normal manner. Usually by this time the drive feature: slot, socket, hex head, is damaged beyond use, or even the entire head might be broken off from the shaft. In this case, the male and female heads are locked together due to rust, corrosion, the improper use of an overly strong bonding agent. In some cases, a screw might have bottomed out in a too shallow hole leaving its bottom swedged in place with overly aggressive tightening. A frozen screw can happen when a PERMAMENT thread-locking compound is incorrectly applied where a reversable (REMOVABLE) compound should have been used.

For sufficiently large screws, it might be possible to drill a specified diameter hole into the screw as close as possible to the center so that a tapered helical screw extractor can be driven into the hole in the loosening direction. Sometimes this works. Other times it doesn’t.

https://en.wikipedia.org/wiki/Screw_extractor

There are several alternatives, some of which can only be done in well-equipped shop. On a large enough workpiece, such as a stamping die, the offending screw can be drilled out using a larger drill diameter for the tap of a larger screw. Then the hole is plugged with a the larger sized glued-in threaded rod or screw of a material soft enough that it can be drilled and tapped with the required thread. The plug must then be leveled flush with the surrounding area. Then the hole of the correct size is carefully positioned, drilled and tapped to restore it.

For particularly tough alloy screws, a carbide drill might be required. If so, this should be done on a drill press or milling machine with fine feed so that the drill can make its way slowly through the material without destroying itself. Larger sized holes might require step drilling. That’s where the center of the hole is made with a smaller drill, and then the hole is drilled to the required size with a larger drill. Taking out the center first with a smaller drill greatly reduces the resistance when drilling the final diameter.

Here’s an example of drilling, plugging, and retaping a damaged hole. I recently received a manufacturer’s sealed box containing a Beseler 8086 enlarger lens board "Mounted 39 mm Leica Flange" via eBay purchase. Both the lens board and flange are aluminum alloy.

The flange has three equally spaced screw holes countersunk for flathead screws to mount the flange to the lens board. The screws installed were #2-56 round head screws, OD = 0.086”/2.18 mm. The heads stuck upward so that a lens could not be mounted. One screw head was particularly high. When I disassembled the flange from the board, the underlying problem was evident. Two of the screw holes were positioned correctly. But the third hole was nearly half a screw diameter out of position. That forced all three round head screws badly out of position in assembly. Round head screws prevented mounting a lens. The botched assembly was unusable.

My solution was to drill out the useless out-of-position hole and tap it for a #4-40 screw, diameter 0.110”/2.79 mm. It wasn't possible to use a larger screw because the required tap drill would have broken out into the large clearance hole for the locating ridge of the flange (holes close to the edge).

I used a brass screw because it’s soft enough to drill and tap. I glued the brass screw into the lens board with Loctite 620 PERMANENT bonding compound and left it overnight for the bond to reach maximum strength.

Then I used a fine-tooth hacksaw blade to trim off the excess screw length. I finished with a Dremel using abrasive wheels to make the brass plug flush to the surrounding surface. I installed the flange with two proper flat head screws and transferred the missing hole position from the flange into the brass plug. Due to the overlap, the resulting #2-56 tapped hole was partly into the aluminum lens broad and partly into the brass plug and well-centered in the screw hole of the mounted flange.

It’s now perfectly usable and the flange covers the repair. Such a repair is best done on a drill press or milling machine with proper work-holding device. With a milling machine, a small-diameter end mill could have been used to mill the plug flush to the surrounding area. Much easier.

 

[Chan Tran]

Camera screws are too small so it would be very difficult. For larger bolt I would drill them for the extractor and using a left hand drill bit. Sometimes the screw would come out during the drilling.

 

[Tel]

I treat drilling-out as a last desperate solution, always with the caveat that I might end up drilling out a larger diameter hole than the screw shank and have to re-thread that to fit a larger screw. A messy and sometimes ineffective solution. I’ve found solvents very effective at loosening screws (acetone, for instance) and heat also. Applying a hot soldering iron to the screw head (with a clean tip—no solder on it) for a generous amount of time will often loosen a badly stuck screw. And a generous application of acetone is good for dissolving thread-locking compounds.

 

[Sirius Glass]

I have removed stubborn screws on motorcycles and automobiles. One drills a small diameter hole in the stubborn screw and then using a screw extractor, called an "easy-out", held in a handle [so one can get a hold on the screw extractor] twist the extractor in a counterclockwise direction. On motorcycles I often used a impact driver to hold the tool and when hit on the end provides a counterclockwise torque on the screw.

 

[4season]

I've had some success with these:

https://www.ebay.com/itm/305265493245

Kind of expensive even when purchased directly from PRC sellers, and they seem to wear out after a few uses, but so far I haven't found anything better. The idea is that you firmly press the tip of the tool onto the broken end of the screw, and attempt to unscrew it. The teeth of the tool frequently break in the process.

And if anyone's looking for tiny drill bits, I've purchased some awful ones from AliExpress: I think they were designed for working with softer materials such as PCBs, and quickly became dull. So the next time, I specified "titanium nitride" and these gold-colored bits have been great:

https://www.aliexpress.us/item/2251832404765245.html

I don't recall if this is the exact vendor I used, but mine have labels marked "Shenzhen Shiyi Technology Co., Ltd" and also "Evatmaster Consulting GmbH"

 

[Andreas Thaler]

I often encounter these nearly impossible-to-remove screws. If I can avoid drilling them out, I leave them alone and loosen other screws.

You don’t always have the luxury of being able to choose

 

[Andreas Thaler]

Thank you for all the detailed information and advice!

You know my method, but I don't always succeed in removing the remaining screw:

Milling out the screw head was possible with almost no damage to the bayonet. I used a diamond cutter on the Dremel.

The scratches caused by slipping were caused by inattention and could have been avoided.

I used the Engineer PZ-57 pliers (Nejisaurus) to unscrew the rest of the screw from the bayonet support.

Post in thread 'Minolta (Maxxum/Alpha) 7000 AF: Aperture issues resolved/shortcut; LCDs, aperture ring, shutter unit replaced; aperture solenoid cleaned'
https://www.photrio.com/forum/threa...aperture-solenoid-cleaned.211422/post-2868035

 

[forest bagger]

You don’t always have the luxury of being able to choose

That's right, Andreas.
But the main problem with drilled out screw heads is the remaining stump!

 

[Andreas Thaler]

Here's another recent example from my Minolta 9000 AF threads.

In order to clean the sticky damper residue from the Copal S shutter curtains, I had to disassemble it.

Four small, flat-headed screws had to be removed. One wouldn't come off, and applying pressure to the sensitive unit with a screwdriver was to avoid.

The Dremel with diamond cutter saved the project; the rest of the screw remained in the bushing, and epoxy replaced the screw.

When it comes to being able to continue working, destructive methods can also be considered.

 

[Paul Howell]

What do watchmakers use to loosen tight fitting or jammed screws?

 

[reddesert]

I've drilled out a screw head to the depth where the remaining bits of the head had no strength and so I could get the top piece off, then I think I was able to use pliers on the stub to twist the shaft out. This was on a ski binding, not a delicate camera, so centering the drill bit and applying force was easier than on a camera. The material of the screw was tedious to drill, though. Subsequently, I got smarter and got an inexpensive set of left-hand drill bits and screw extractors. In my limited experience with these, sometimes the left-hand drill bit will bite into the screw enough to loosen it, and you don't even need to use the screw extractor.

 

[Nimbus62]

to loosen tight fitting screws,
I check that there is no varnish. Disolv it with gasoline C (or Zippo).
I hit the head of the screw with a flat pin punch.
Knock permit to loosen the screw threads Use a watchmaker's hammer. Build appropriate pin and requires supporting the opposite part to avoid deforming or twisting the part.

I use a screwdriver well suited to the screw:
- slotted head screw, choose the width and thickness carefully, machine the screwdriver blade so that it fits perfectly the head.
- cruciform screw, use the appropriate recess (Philips of Japan and right size), I have a set of new screew driver for that purpose, to avoid using worn set.

If the head is damaged....
to drill I use a milling machine with a small tool and flat tip to cut it flat at top.
This is possible up to a diameter of 2mm and provided that the part can be clamped on the machine. Generally I spend more time clamping the part than drilling it.
Have to align with the part with the cutting tool using X/Y table.
For less than 2mm is really difficult. NEED TO BE CLAMP otherwise it is at risk because milling is really dangerous evenif it is a small part.

Depend of the shape of the head:
As it is flat then possible :
to hit it,
to I drill, do it with a very short drill bit or better with a flat end mill (need very small tools)

To extract the remaining part of the screw, I use a "left turner" or a fine watchmaker's cutting broaches set (I have a old set of such tool broken at the end and adapted to the diameter of the drilled hole

I have a set of tools from my father, it helps...

To summary, many tools are hand made. And you cannot success every time...

 

[dxqcanada]

I work on older cameras ... and they tend to have many brass screws ... these tend to break easily when the incorrect driver head is used ... especially set/grub screws. I've had to drill out these screws.
As Nimbus stated ... to drill them out you need a rigid setup. I use a square ended milling bit just slightly smaller than the screw and drill down (with blind screw holes you go slow) exactly in the centre. Then I can pick out the left over screw bits, which can leave the internal threading intact.

Milling cutters, 3 pcs. (1/32", 5/64", 7/64")

These double flute cutters are made from solid tungsten and are to be used for clockwise cutting. The fishtail profile ensures cutting to the center, allowing boring. Usable on cast iron, hardened cast iron, steel, cast steel, brass, aluminum, and even glass, plastics and carbon fiber. The set...

proxxon-us-shop.com

 

[Truzi]

I work on older cameras ... and they tend to have many brass screws ... these tend to break easily when the incorrect driver head is used ... especially set/grub screws. I've had to drill out these screws.
As Nimbus stated ... to drill them out you need a rigid setup. I use a square ended milling bit just slightly smaller than the screw and drill down (with blind screw holes you go slow) exactly in the centre. Then I can pick out the left over screw bits, which can leave the internal threading intact.

Milling cutters, 3 pcs. (1/32", 5/64", 7/64")

These double flute cutters are made from solid tungsten and are to be used for clockwise cutting. The fishtail profile ensures cutting to the center, allowing boring. Usable on cast iron, hardened cast iron, steel, cast steel, brass, aluminum, and even glass, plastics and carbon fiber. The set...

proxxon-us-shop.com

My grandfather would to that with bolts when working on my old rusty car when I was a teen. He was able to do that, then run a tap through to clean out the threads. I never got the hang of it.

I can't imagine how difficult this would be on tiny screws.

 

[mshchem]

Is there anyway to apply sufficient heat to such a tiny screw (before/without stripping) ?

Seems like mechanics, of larger things, don't attempt to remove certain types of hardware without applying a torch to the article. Clearly you can't put a flame to a camera, but is conducting heat into a screw a possibility??

Very tiny impact wrenches?

 

[F4U]

The first thing to get through your head when a screw gets broken off or the head is too chewed up, is to resign yourself to a complete game-over scenario. Actually extracting the screw after that realization is a happy miracle. But never anticipate it. It almost never happens.

 

[Don_ih]

is conducting heat into a screw a possibility?

People use a hot soldering iron. It can work.

 

[mshchem]

People use a hot soldering iron. It can work.

Humans are just naturally torque . Don't know my own strength!

 

[Andreas Thaler]

Using a butane torch (Dremel Versatip), I was able to loosen a glued stuck screw in a Minolta bayonet. The soldering iron couldn't do it, despite tinning the screw head.

The problem is that the surrounding metal conducts the heat, so it requires high power, which, however, endangers other components in the vicinity that aren't heat-resistant.

It remains laborious.