Topics

Extracting a knob grubscrew


Keith
 

Need to remove the horizontal control knob on my 576 so I can remove the board to get at the display selector board. One of the grubscrews undoes easily enough, but the other appears to have its hex slot stripped. A 1/16th allen key just rotates in the slot.

Any tips on how this could be removed? I don't have a screw extractor small enough (I presume the grubscrew is 1/8th ?).


snapdiode
 

They are typically 1/20" or 0.050" keys. Sometimes it's Bristol drive but if someone forced a hex key in there it's probably not a Bristol drive anymore.

Unfortunately I have found no way to extract a stuck set screw of that size. You might try a 1.3mm key, sometimes they really are 1.3 and not 1.27 so you get a bit more grip. I don't know, seems random.


Tom Lee
 

I'm sure you'll get a lot of great suggestions. Until then, here are my bodges. One is to use a sacrificial metric wrench that fits tightly, perhaps with a little tapping to encourage insertion. A Dremel comes in handy to fashion one to fit.

Another method is to dip the wrench in a little valve grinding compound to take up the extra space and give the tool a little more bite.

Those usually work for me. In very desperate cases I've used a tiny drill bit to mill out a groove to convert into a slot head. Then a standard screwdriver might get the job done.

Good luck!

Tom

Sent from an iThing, so please forgive the typos and brevity

On Feb 1, 2021, at 11:33, keith@peardrop.co.uk wrote:

Need to remove the horizontal control knob on my 576 so I can remove the board to get at the display selector board. One of the grubscrews undoes easily enough, but the other appears to have its hex slot stripped. A 1/16th allen key just rotates in the slot.

Any tips on how this could be removed? I don't have a screw extractor small enough (I presume the grubscrew is 1/8th ?).





Steve Hendrix
 

One other thing comes to mind: With a hex key, you don't want to turn slowly. That allows the flats to push out and seize the threads ever tighter. To break a screw loose you want a sudden turn. Good luck, BTDT.

Steve Hendrix

At 2021-02-01 02:53 PM, Tom Lee via groups.io wrote:
I'm sure you'll get a lot of great suggestions. Until then, here are my bodges. One is to use a sacrificial metric wrench that fits tightly, perhaps with a little tapping to encourage insertion. A Dremel comes in handy to fashion one to fit.

Another method is to dip the wrench in a little valve grinding compound to take up the extra space and give the tool a little more bite.

Those usually work for me. In very desperate cases I've used a tiny drill bit to mill out a groove to convert into a slot head. Then a standard screwdriver might get the job done.

Good luck!

Tom

Sent from an iThing, so please forgive the typos and brevity

On Feb 1, 2021, at 11:33, keith@peardrop.co.uk wrote:

Need to remove the horizontal control knob on my 576 so I can
remove the board to get at the display selector board. One of the grubscrews undoes easily enough, but the other appears to have its hex slot stripped. A 1/16th allen key just rotates in the slot.

Any tips on how this could be removed? I don't have a screw
extractor small enough (I presume the grubscrew is 1/8th ?).






Miguel Work
 

Hi
When I find in that situation I use a torx drive, the size that best fits, it has always worked for me

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de snapdiode via groups.io
Enviado el: lunes, 1 de febrero de 2021 20:47
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Extracting a knob grubscrew

They are typically 1/20" or 0.050" keys. Sometimes it's Bristol drive but if someone forced a hex key in there it's probably not a Bristol drive anymore.

Unfortunately I have found no way to extract a stuck set screw of that size. You might try a 1.3mm key, sometimes they really are 1.3 and not 1.27 so you get a bit more grip. I don't know, seems random.







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SCMenasian
 

Maybe a dab of epoxy at the tip of the wrench would come to the rescue (if you don't end up epoxying the screw in place)


Renée
 

sometimes a piece of rubber glove over the key will assist in making a tighter fit.
Renée

On 2/1/21 12:01 PM, Miguel Work wrote:
Hi
When I find in that situation I use a torx drive, the size that best fits, it has always worked for me

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de snapdiode via groups.io
Enviado el: lunes, 1 de febrero de 2021 20:47
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] Extracting a knob grubscrew

They are typically 1/20" or 0.050" keys. Sometimes it's Bristol drive but if someone forced a hex key in there it's probably not a Bristol drive anymore.

Unfortunately I have found no way to extract a stuck set screw of that size. You might try a 1.3mm key, sometimes they really are 1.3 and not 1.27 so you get a bit more grip. I don't know, seems random.







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Find out more here: https://bit.ly/2zCJMrO



 

I have had success using a torx driver and angling it to wedge it in, applying a high down force along with the angling force, and turning very slowly so that it doesn't slip and further turn out the hex opening, or the bit on the torx driver. I had thought that I was ruining the torx driver, but it seems to have survived the ordeal relatively well. Still, it's best to use a sacrificial tool for this process.

-- Jeff Dutky


Paul Amaranth
 

These things rarely get seized; they are just really tight.

If you can heat the screw with a very small soldering iron and let it cool
(or shoot it with freeze spray), it might loosen up enough to get out.

Paul

On Mon, Feb 01, 2021 at 01:32:47PM -0800, Jeff Dutky wrote:
I have had success using a torx driver and angling it to wedge it in, applying a high down force along with the angling force, and turning very slowly so that it doesn't slip and further turn out the hex opening, or the bit on the torx driver. I had thought that I was ruining the torx driver, but it seems to have survived the ordeal relatively well. Still, it's best to use a sacrificial tool for this process.

-- Jeff Dutky
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Larry McDavid
 

I have sometimes had to drill out the set screw. The damaged hex recess provides a guide for the drill bit.

I use a left-hand drill in my vertical mill where I can easily reverse the rotation direction. Left-hand drills are available in a full range of sizes, down to #80. I often find that in drilling the hardened set screw that the drill will catch in the screw enough to actually loosen the setscrew.

Even if that does not happen, you can increase the size of the drill bit and eventually remove so much set screw material that is is too weak to retain itself. Just don't use a drill larger than the minor diameter of the internal thread in the knob.

This approach with left-hand drills works in many kinds of stuck fasteners. One of my local machine tool dealers has a cabinet full of left-hand drills; I went through it and picked out a bunch of sizes to keep on-hand.

I have hex keys in Imperial Inch and metric, and Bristol with different numbers of flutes depending on size. There is no Torx that small that I am aware of. I often work on microscopes and some cameras that need this approach.

Regarding larger size screw heads, remember that both Tek and HP used PoziDrive screw head fasteners. These are NOT Phillips even though they look quite similar. The distinct advantage of PoziDriv is that the driver does not cam out of the head as it does in a Phillips head.

But, if a Japanese product has what looks like a Phillips, remember that it is more likely a JIS head. So, you need to have Phillips, PoziDriv and JIS screw drivers in your tool kit. You really need the correct tool for the job!

Larry

On 2/1/2021 11:46 AM, snapdiode via groups.io wrote:
They are typically 1/20" or 0.050" keys. Sometimes it's Bristol drive but if someone forced a hex key in there it's probably not a Bristol drive anymore.
Unfortunately I have found no way to extract a stuck set screw of that size. You might try a 1.3mm key, sometimes they really are 1.3 and not 1.27 so you get a bit more grip. I don't know, seems random.
--
Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)


Dave Daniel
 

An EZ-out sometimes works. In one case I had to shorten the EZ-out because it bottomed out before the reversing flutes could engage the ID of the setscrew.

I also have a set of screw extractors (not EZ-outs) that are very short. A lot of times one of the small ones worked well.

DaveD

DaveD

On Feb 1, 2021, at 16:36, Paul Amaranth <paul@auroragrp.com> wrote:

These things rarely get seized; they are just really tight.

If you can heat the screw with a very small soldering iron and let it cool
(or shoot it with freeze spray), it might loosen up enough to get out.

Paul

On Mon, Feb 01, 2021 at 01:32:47PM -0800, Jeff Dutky wrote:
I have had success using a torx driver and angling it to wedge it in, applying a high down force along with the angling force, and turning very slowly so that it doesn't slip and further turn out the hex opening, or the bit on the torx driver. I had thought that I was ruining the torx driver, but it seems to have survived the ordeal relatively well. Still, it's best to use a sacrificial tool for this process.

-- Jeff Dutky

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows





Dave Casey
 

For the Tek screw in question that takes a 1/16 Allen key, I have
successfully drilled them out with a 3/16" bit without damage to the knob's
threads. The screws are not 4-40 thread, but a 4-40 tap will help remove
the remnants of the drilled out set screw.

Dave Casey

On Mon, Feb 1, 2021 at 3:37 PM Larry McDavid <lmcdavid@lmceng.com> wrote:

I have sometimes had to drill out the set screw. The damaged hex recess
provides a guide for the drill bit.

I use a left-hand drill in my vertical mill where I can easily reverse
the rotation direction. Left-hand drills are available in a full range
of sizes, down to #80. I often find that in drilling the hardened set
screw that the drill will catch in the screw enough to actually loosen
the setscrew.

Even if that does not happen, you can increase the size of the drill bit
and eventually remove so much set screw material that is is too weak to
retain itself. Just don't use a drill larger than the minor diameter of
the internal thread in the knob.

This approach with left-hand drills works in many kinds of stuck
fasteners. One of my local machine tool dealers has a cabinet full of
left-hand drills; I went through it and picked out a bunch of sizes to
keep on-hand.

I have hex keys in Imperial Inch and metric, and Bristol with different
numbers of flutes depending on size. There is no Torx that small that I
am aware of. I often work on microscopes and some cameras that need this
approach.

Regarding larger size screw heads, remember that both Tek and HP used
PoziDrive screw head fasteners. These are NOT Phillips even though they
look quite similar. The distinct advantage of PoziDriv is that the
driver does not cam out of the head as it does in a Phillips head.

But, if a Japanese product has what looks like a Phillips, remember that
it is more likely a JIS head. So, you need to have Phillips, PoziDriv
and JIS screw drivers in your tool kit. You really need the correct tool
for the job!

Larry


On 2/1/2021 11:46 AM, snapdiode via groups.io wrote:
They are typically 1/20" or 0.050" keys. Sometimes it's Bristol drive
but if someone forced a hex key in there it's probably not a Bristol drive
anymore.

Unfortunately I have found no way to extract a stuck set screw of that
size. You might try a 1.3mm key, sometimes they really are 1.3 and not 1.27
so you get a bit more grip. I don't know, seems random.
--
Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)






shalopt
 

I would try some PT Blaster turn knob so it does not run out let sat for a day.
Works great on rusty frozen bolts/nuts so far have not it damage plastic.
gary g


aldue
 

I use lefty, counter clockwise twist drills. A tiny triangle file may work
also. Model railroad hobbyists use the files. You may have to grind the
point a tad., aldue

On Mon, Feb 1, 2021, 2:33 PM <keith@peardrop.co.uk> wrote:

Need to remove the horizontal control knob on my 576 so I can remove the
board to get at the display selector board. One of the grubscrews undoes
easily enough, but the other appears to have its hex slot stripped. A
1/16th allen key just rotates in the slot.

Any tips on how this could be removed? I don't have a screw extractor
small enough (I presume the grubscrew is 1/8th ?).






-
 

I use a small Torx bit to remove them. The Torx bits are tapered and you
can usually find one that will fit into a striped allen screw. Press the
Torx bit into the screw tightly so that it doesn't slip and further strip
the hex in the screw.

In general when working with set screws, always make sure that your hex
bit is in good condition and it's corners aren't rounded off. If they are
then grind the bit back some to get fresh corners. Also whenever you remove
a set screw check it to be sure it's not starting to strip. If it is then
replace it.

On Mon, Feb 1, 2021 at 2:33 PM <keith@peardrop.co.uk> wrote:

Need to remove the horizontal control knob on my 576 so I can remove the
board to get at the display selector board. One of the grubscrews undoes
easily enough, but the other appears to have its hex slot stripped. A
1/16th allen key just rotates in the slot.

Any tips on how this could be removed? I don't have a screw extractor
small enough (I presume the grubscrew is 1/8th ?).