Finding not-so-odd parts for scopes, e.g., metric screws

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Anyone here have pointers to sources for knurled-head screws?

I have a couple of scopes/mounts which have lost some screws and want to
replace them. I can get nominal replacements from McMaster-Carr, but
the match is not-so-good. E.g., I need an M4-0.7mm pitch knurled-head
screw with a 10mm length which is the screw that holds an eyepiece in
place for the StarMax 127. McMaster-Carr's version has a 20mm diameter
knurled-head vs the 8mm diameter of the original. Although that might
be handy in the cold.... Another example is the screw for the CG-5
polar alignment scope. It's an M3-0.5mm. Again, I can get something
that technically replaces it, but the head diameter is huge. So, before
I go that route, I wanted to see if anyone else knows of a source.

The local hardware stored, including the big places like Home Depot and
Lowe's are hopeless, at least here in Brooklyn....

TIA,

roland
- --
PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD RL Enterprises
6818 Madeline Court
Brooklyn, NY 11220
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Roland Roberts:
Anyone here have pointers to sources for knurled-head screws?

I have a couple of scopes/mounts which have lost some screws and want to
replace them. I can get nominal replacements from McMaster-Carr, but
the match is not-so-good. E.g., I need an M4-0.7mm pitch knurled-head
screw with a 10mm length which is the screw that holds an eyepiece in
place for the StarMax 127. McMaster-Carr's version has a 20mm diameter
knurled-head vs the 8mm diameter of the original. Although that might
be handy in the cold.... Another example is the screw for the CG-5
polar alignment scope. It's an M3-0.5mm. Again, I can get something
that technically replaces it, but the head diameter is huge. So, before
I go that route, I wanted to see if anyone else knows of a source.

The local hardware stored, including the big places like Home Depot and
Lowe's are hopeless, at least here in Brooklyn....

Try e-mailing
http://www.universalastronomics.com/. Although I didn't see hardware
on his web site, he posted a notice here on 31 March stating that he
would be at NEAF http://www.davidillig.com/neaf with a selection of
nuts, bolts, washers, and the like. He was there, and he had a nice
selection.

Davoud

--
usenet *at* davidillig dawt com

Roland,


Scopestuff has many of the replacement screws your looking for. I will
say something for buying those larger diameter head ones though it
proabably will work BETTER than the original. Most chinese scopes have
seriously undersized screws and the repalcements will probably fit
better both in the threads and in the hands.


Roland Roberts wrote:
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Hash: SHA1

Anyone here have pointers to sources for knurled-head screws?

I have a couple of scopes/mounts which have lost some screws and want
to
replace them. I can get nominal replacements from McMaster-Carr, but
the match is not-so-good. E.g., I need an M4-0.7mm pitch
knurled-head
screw with a 10mm length which is the screw that holds an eyepiece in
place for the StarMax 127. McMaster-Carr's version has a 20mm
diameter
knurled-head vs the 8mm diameter of the original. Although that
might
be handy in the cold.... Another example is the screw for the CG-5
polar alignment scope. It's an M3-0.5mm. Again, I can get something
that technically replaces it, but the head diameter is huge. So,
before
I go that route, I wanted to see if anyone else knows of a source.

The local hardware stored, including the big places like Home Depot
and
Lowe's are hopeless, at least here in Brooklyn....

TIA,

roland
- --
PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD RL Enterprises
6818 Madeline Court
Brooklyn, NY 11220
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http://mailcrypt.sourceforge.net/

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www.scopestuff.com

I've bought replacements from them often. A+ to deal with...

Doink
"Roland Roberts" wrote in message
...
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Anyone here have pointers to sources for knurled-head screws?

I have a couple of scopes/mounts which have lost some screws and want to
replace them. I can get nominal replacements from McMaster-Carr, but
the match is not-so-good. E.g., I need an M4-0.7mm pitch knurled-head
screw with a 10mm length which is the screw that holds an eyepiece in
place for the StarMax 127. McMaster-Carr's version has a 20mm diameter
knurled-head vs the 8mm diameter of the original. Although that might
be handy in the cold.... Another example is the screw for the CG-5
polar alignment scope. It's an M3-0.5mm. Again, I can get something
that technically replaces it, but the head diameter is huge. So, before
I go that route, I wanted to see if anyone else knows of a source.

The local hardware stored, including the big places like Home Depot and
Lowe's are hopeless, at least here in Brooklyn....

TIA,

roland
- --
PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD RL Enterprises
6818 Madeline Court
Brooklyn, NY 11220
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Version: GnuPG v1.2.6 (GNU/Linux)
Comment: Processed by Mailcrypt 3.5.8 http://mailcrypt.sourceforge.net/

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=g3w5
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wrote:

Scopestuff has many of the replacement screws your looking for. I
will
say something for buying those larger diameter head ones though it
probably will work BETTER than the original. Most Chinese scopes have
seriously undersized screws and the replacements will probably fit
better both in the threads and in the hands.


Red Alert! :-)

There is a danger that cranking hard on a small, larger headed screw
will:

a) Strip the fine thread in the thin (relatively weak) material.
b) Damage the object which the screw holds fast.
c) Spoil the finish on the object which the end of the screw presses
against.

Be careful out there! The small-headed screws are a bore in use. But
often the only way a tiny screw will survive for very long. What will
you do with the component once the screw-thread is stripped?

If you tap (use a thread cutting tool) to make a larger Metric thread
in place of the smaller original (to fit a bigger diameter screw) the
pitch of the thread is longer. Which means even fewer threads will
exist in the thin-wall material of the component. Only redesigning the
component with heavier cross-sections will allow you to use a bigger
screw safely. That's why better scopes are heavier. Thicker materials
are used!

If you do run out of luck and strip a thread you might get away with
recutting the threads slightly larger to the British BA thread system.
Which has very fine threads in comparison with the coarser Metric
threads. The BA system was much used in thin brass in the past.

Though you can always silver-solder a big head onto a small BA screw I
really would not recommend this with Metric threaded screws.

A clockmaker/watch repairer might be able to help if you can't source
BA taps from your tool merchant. Then all you need is to source
suitable BA screws. The clockmaker may be able to help there too. Good
luck! :-)

Regards
Chris.B

"chris" == chris b writes:

chris wrote:

Scopestuff has many of the replacement screws your looking for. I
will say something for buying those larger diameter head ones
though it probably will work BETTER than the original. Most
Chinese scopes have seriously undersized screws and the
replacements will probably fit better both in the threads and in
the hands.


chris Red Alert! :-)

chris There is a danger that cranking hard on a small, larger
chris headed screw will:

[...good tips elided...]

Thanks for the warnings.

Ideally, I would have liked to replace most of these with nylon or
similar, especially those that come in contact with eyepieces. I will
happily replace stripped screws in exchange for knowing I don't have to
worry about damaging the eyepiece or the tapped threads.

Alas, I can't find a source for M3 or M4 nylon thumb screws or knurled
head screws.

regards,

roland
--
PGP Key ID: 66 BC 3B CD
Roland B. Roberts, PhD RL Enterprises
6818 Madeline Court
Brooklyn, NY 11220

ScopeStuff does supply both nylon and stainless steel thumbscrews
in metric and SAE sizes, and we can get sizes that are not listed
on our screw pages: http://www.scopestuff.com

Unlisted sizes may not be cheap in the long run, but we can get
them. International shipping and "customs service" unfortunately
adds cost that far exceed the cost of a few screws.

Also, we can supply threading taps of almost any size, but really
odd ones will take a week or two before we can ship them.

The ideal situation is to use screws that will strip before the
body of your expensive gismo strips, but that is not always the
case.

Nylon screws are very gentile on eyepieces, and gravity will
normally hold an eyepiece in place even if the screw fails...
Except in the southern hemisphere, of course, where being on
the bottom half of the world may allow eyepieces to slide up
and out spontaneously. ;=}

We don't recommend nylon screws for holding diagonals, as the
risk of my diagonal hitting the dirt isn't worth worrying about a few
little marks on the barrel! For eyepieces, nylon screws are dandy
if the eyepiece is facing up.

We sell rounded tip stainless steel thumbscrews that have caps
that are comfortable to use and they are gentile on eyepieces.
I don't recommend cranking down on them really hard, as
something will give!

Ranting Side Note
Those who started the whole compression ring trend must also keep
their cars on blocks so the tires don't touch the ground, and I
wonder if they often uncap their beautiful white refractors. My
eyepieces and diagonals are loved and cared for, but I use them
and they have little marks on the barrels from screws. Resale
value?? Secondary issue! Compression rings are gentle on
eyepieces, but they don't center things any better than grub
screws. Precision machining is what makes most compression band
accessories better than stock accessories, not the compression
bands.
/Rant

Clear skies,
Jim


On 28 Apr 2005 01:06:18 -0700, wrote:

wrote:

Red Alert! :-)

There is a danger that cranking hard on a small, larger headed screw
will:

a) Strip the fine thread in the thin (relatively weak) material.
b) Damage the object which the screw holds fast.
c) Spoil the finish on the object which the end of the screw presses
against.

Be careful out there! The small-headed screws are a bore in use. But
often the only way a tiny screw will survive for very long. What will
you do with the component once the screw-thread is stripped?

If you tap (use a thread cutting tool) to make a larger Metric thread
in place of the smaller original (to fit a bigger diameter screw) the
pitch of the thread is longer. Which means even fewer threads will
exist in the thin-wall material of the component. Only redesigning the
component with heavier cross-sections will allow you to use a bigger
screw safely. That's why better scopes are heavier. Thicker materials
are used!

If you do run out of luck and strip a thread you might get away with
recutting the threads slightly larger to the British BA thread system.
Which has very fine threads in comparison with the coarser Metric
threads. The BA system was much used in thin brass in the past.

Though you can always silver-solder a big head onto a small BA screw I
really would not recommend this with Metric threaded screws.

A clockmaker/watch repairer might be able to help if you can't source
BA taps from your tool merchant. Then all you need is to source
suitable BA screws. The clockmaker may be able to help there too. Good
luck! :-)

Regards
Chris.B