Mach2GTO counterweight shaft stuck midway #Mach2GTO


Christopher M
 

Wood is more heat resistant than a strap wrench.  If you freeze the metal, then torch heat the stuck insert without heating the CW shaft, then clamp the hot threads in sacraficial (throw away) wood while gripping the CW shaft with the strap wrench, that might work better.  For better clamping, drill a hole in a sacraficial block of wood or plywood, and cut to the hole from one side.  You make a round clamp which will be more even than just squishing between two blocks of wood.  In the attached picture I'm using a hole "clamp" to get a much more flexible ring off an adapter.  This trick will be harder with the smaller diameter threaded insert, but it can help.


Carl Björk
 

Very interesting technique, thanks for sharing it!


On Tue, Aug 9, 2022 at 01:37 AM, Christopher M wrote:
Wood is more heat resistant than a strap wrench.  If you freeze the metal, then torch heat the stuck insert without heating the CW shaft, then clamp the hot threads in sacraficial (throw away) wood while gripping the CW shaft with the strap wrench, that might work better.  For better clamping, drill a hole in a sacraficial block of wood or plywood, and cut to the hole from one side.  You make a round clamp which will be more even than just squishing between two blocks of wood.  In the attached picture I'm using a hole "clamp" to get a much more flexible ring off an adapter.  This trick will be harder with the smaller diameter threaded insert, but it can help.


Christopher Erickson
 

NEVER use WD-40 on ANY part of a telescope or mount. It is a PENETRANT, NOT a lubricant. It penetrates into everything. It dissolves and ruins real lubricants, it can ruin optical coatings, it can ruin circuit boards, and it can actually accelerate corrosion.

A drop of LUBRICANT in counterweight shaft threads is good. Cleaning dirty, contaminated threads with a toothbrush is good. And doing both is even more goodness. LOL. 

Using a [slightly oily] rag to clean shaft threads before assembly might do the trick as well. Place rag around threads, grab rag and threads and then "unscrew" the threads from the rag and your hand.

If your threads are really dirty with something that is really stuck to them, a metal brush and some Break-Free CLP might be required. Followed by the old "unscrew from an oily rag" trick. (Nod to Don Adams.)

Currently my favorite lubricant is Break-Free CLP (the older brown formula over the newer blue formula) but there are lots of good lubes out there for various applications. 

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   


On Mon, Aug 8, 2022, 11:18 AM Brian Valente <bvalente@...> wrote:
>>> And the only precaution I have ever taken was
to apply a thin coat of WD40 to the counterweight bar threads

I agree with adding something to threads, but I prefer CLP. I may have lifted that from Christopher?

On Mon, Aug 8, 2022 at 2:17 PM Brian Kaine <briankaine@...> wrote:
Hi Carl,

Sorry to hear about the problem, but I am sure that Astro-Physics will have a
solution for you. Their support is the best in the world!

Regarding this as being an issue with an older batch of mounts, I can only add
that I own the first production sample, #M20011. I have never encountered this
problem, so it is likely hit-or-miss. And the only precaution I have ever taken was
to apply a thin coat of WD40 to the counterweight bar threads. An earlier AP900
mount that I own developed a nasty squeek when screwing in the bar (although
it had never siezed up). The oil put a stop to that problem.

Brian



--


Bill Long
 

Agree with Chris here. 

Spit is probably better than WD40. 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Christopher Erickson <christopher.k.erickson@...>
Sent: Tuesday, August 9, 2022 2:42 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Mach2GTO counterweight shaft stuck midway
 
NEVER use WD-40 on ANY part of a telescope or mount. It is a PENETRANT, NOT a lubricant. It penetrates into everything. It dissolves and ruins real lubricants, it can ruin optical coatings, it can ruin circuit boards, and it can actually accelerate corrosion.

A drop of LUBRICANT in counterweight shaft threads is good. Cleaning dirty, contaminated threads with a toothbrush is good. And doing both is even more goodness. LOL. 

Using a [slightly oily] rag to clean shaft threads before assembly might do the trick as well. Place rag around threads, grab rag and threads and then "unscrew" the threads from the rag and your hand.

If your threads are really dirty with something that is really stuck to them, a metal brush and some Break-Free CLP might be required. Followed by the old "unscrew from an oily rag" trick. (Nod to Don Adams.)

Currently my favorite lubricant is Break-Free CLP (the older brown formula over the newer blue formula) but there are lots of good lubes out there for various applications. 

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Mon, Aug 8, 2022, 11:18 AM Brian Valente <bvalente@...> wrote:

>>> And the only precaution I have ever taken was
to apply a thin coat of WD40 to the counterweight bar threads

I agree with adding something to threads, but I prefer CLP. I may have lifted that from Christopher?

On Mon, Aug 8, 2022 at 2:17 PM Brian Kaine <briankaine@...> wrote:
Hi Carl,

Sorry to hear about the problem, but I am sure that Astro-Physics will have a
solution for you. Their support is the best in the world!

Regarding this as being an issue with an older batch of mounts, I can only add
that I own the first production sample, #M20011. I have never encountered this
problem, so it is likely hit-or-miss. And the only precaution I have ever taken was
to apply a thin coat of WD40 to the counterweight bar threads. An earlier AP900
mount that I own developed a nasty squeek when screwing in the bar (although
it had never siezed up). The oil put a stop to that problem.

Brian



--


Brian Kaine
 

Gentlemen,

I have been using WD40 on various metal surfaces for over 30 years
(including every hinge and drawer runner in my home) and have never
ONCE had an adverse reaction. And that AP900 shaft was treated
shortly after I received the mount in 2007; no deterioration at all.

Not trying to be argumentative, only recounting MY experience.

Brian

PS: My neighbor is a remodeling contractor. He routinely uses WD40
on a major investment; his tools.


Mike Johnson
 

I use a dab of anti seize compound on the threads to prevent this situation. Available at any auto parts store. I also use it on spark plug threads when changing the plugs on an auto or marine engine.


Cheng-Yang Tan
 

Personally, I think it's just messy to use anti-seize and lube on a counterweight shaft which I've never used before the improvement with steel inserts. The root of the problem is stainless steel on stainless steel that can give cold welds (The seizing of Stainless Steel fasteners | Fabory). This is a well known problem. I'd suggest that the insert material be changed from stainless steel to perhaps bronze to alleviate this problem.




cytan

On Tuesday, August 9, 2022 at 10:41:52 AM CDT, Mike Johnson <mljjaj@...> wrote:


I use a dab of anti seize compound on the threads to prevent this situation. Available at any auto parts store. I also use it on spark plug threads when changing the plugs on an auto or marine engine.


ap@CaptivePhotons.com
 

On Tue, Aug 9, 2022 at 11:41 AM, Mike Johnson wrote:
I use a dab of anti seize compound on the threads to prevent this situation.

I've been putting a dab of Lubriplate 105 on all screws and treads for the last couple years, I also saw it once recommended for worm gears (though if I need to re-grease will just order a kit from AP). 

Is Lubriplate as good, or does a specific anti-seize work better? 

Linwood


fernandorivera3
 

I agree with Cytan 💯%

Fernando


Woody Schlom
 

Here’s a fun thing to do with the original WD-40 that will prevent you from ever using it again on delicate things or locks – or anything other than what it was originally designed for – rust prevention on U.S. Naval ships.

 

Find an old metal tool (preferably a bit rusted) – hammer or screwdriver for example.  Spray some original WD-40 onto a rag and wipe the tool.  Lots of rust should come off.  Wipe it again until the tool is nice and wet and shiny.  Hang the tool up where nothing is touching it.  Leave it for a month or so in a hot garage.

 

After a month or so, examine the tool again.  If it’s been warm enough, I think you’ll find that the WD-40 is now a SOLID coating – just like varnish.  That tool will never rust any more – but think about what would have happened if that now hard varnish coating was inside a lock – or clock – or mount?

 

And yes, I do use it to coat old rusting tools and machinery.  And it works super well.

 

Woody

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Bill Long
Sent: Tuesday, August 9, 2022 2:55 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Mach2GTO counterweight shaft stuck midway

 

Agree with Chris here. 

 

Spit is probably better than WD40. 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Christopher Erickson <christopher.k.erickson@...>
Sent: Tuesday, August 9, 2022 2:42 AM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Mach2GTO counterweight shaft stuck midway

 

NEVER use WD-40 on ANY part of a telescope or mount. It is a PENETRANT, NOT a lubricant. It penetrates into everything. It dissolves and ruins real lubricants, it can ruin optical coatings, it can ruin circuit boards, and it can actually accelerate corrosion.

 

A drop of LUBRICANT in counterweight shaft threads is good. Cleaning dirty, contaminated threads with a toothbrush is good. And doing both is even more goodness. LOL. 

 

Using a [slightly oily] rag to clean shaft threads before assembly might do the trick as well. Place rag around threads, grab rag and threads and then "unscrew" the threads from the rag and your hand.

 

If your threads are really dirty with something that is really stuck to them, a metal brush and some Break-Free CLP might be required. Followed by the old "unscrew from an oily rag" trick. (Nod to Don Adams.)

 

Currently my favorite lubricant is Break-Free CLP (the older brown formula over the newer blue formula) but there are lots of good lubes out there for various applications. 


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

 

On Mon, Aug 8, 2022, 11:18 AM Brian Valente <bvalente@...> wrote:

>>> And the only precaution I have ever taken was
to apply a thin coat of WD40 to the counterweight bar threads

 

I agree with adding something to threads, but I prefer CLP. I may have lifted that from Christopher?

 

On Mon, Aug 8, 2022 at 2:17 PM Brian Kaine <briankaine@...> wrote:

Hi Carl,

Sorry to hear about the problem, but I am sure that Astro-Physics will have a
solution for you. Their support is the best in the world!

Regarding this as being an issue with an older batch of mounts, I can only add
that I own the first production sample, #M20011. I have never encountered this
problem, so it is likely hit-or-miss. And the only precaution I have ever taken was
to apply a thin coat of WD40 to the counterweight bar threads. An earlier AP900
mount that I own developed a nasty squeek when screwing in the bar (although
it had never siezed up). The oil put a stop to that problem.

Brian


 

--


Brian Kaine
 

Hi  Woody,

That may be true; I've never experimented that way. On the other hand, when used carefully
WD40 is marvelous stuff. I was a research scientist in a NASA funded biology lab for nearly
twenty years. Our maintenance techs used it on ultracentrifuge spindles and rotor hubs as
well as on scintillation counter sample delivery chains. Never had a bit of a problem.

And of course, those guys had to know what they were doing. The replacement cost of those
instruments was far beyond that of any mount Astro-Physics ever produced.

Of course I would never suggest using it on delicate electronics or optical surfaces; that's
nonsense. But on the threads of a counterweight shaft; absolutely.

All the best,
Brian



Carl Björk
 

Hi,


I just wanted to give you guys an update.


My shaft is seized solid to the insert and the thread is visibly damaged (look at the first thread on the first post). Unfortunately nothing works.

I must say AP has been extremely responsive and will send replacement parts to me tomorrow.


Now for the insert.
For what I know about it, cold welding is something that can only happen with very pure metals. Metals so pure that even oxydation will make it impossible. IMHO, the reasons for seizures are somewhere else. But besides the design, what counts is solutions and downtime minimisation.
More importantly, as per my shameful experience of damaging aluminium threads, I really see stainless steel inserts as an advantage.

But that is only my own opinion in this given situation ;-)


Yes this is a hassle, BUT yes AP has probably has the best support out there! For me it totally makes up for it.


Cheers everyone!

Looking forward to share great things with my Mach2 ;-P


Cheng-Yang Tan
 

Hi Carl,
   The mechanical engineers and techs that I work with have extensive knowledge of stainless steel. We work with stainless steel everyday because it is used for high vacuum. Stainless steel bolts and nuts seize easily unless we use "never seez" compound which is a mess. Instead we prefer to silver plate all the stainless steel fastening hardware to prevent seizure.

   Anyway, I had started a thread about this problem a year ago and got some info about how to mitigate this problem. See this link:



Anyway, I agree that having an insert is a good idea, but a change of material will certainly lessen or eliminate the cross threading problem.

cytan



   

On Tuesday, August 9, 2022 at 04:29:59 PM CDT, Carl Björk <carl.bjork@...> wrote:


Hi,


I just wanted to give you guys an update.


My shaft is seized solid to the insert and the thread is visibly damaged (look at the first thread on the first post). Unfortunately nothing works.

I must say AP has been extremely responsive and will send replacement parts to me tomorrow.


Now for the insert.
For what I know about it, cold welding is something that can only happen with very pure metals. Metals so pure that even oxydation will make it impossible. IMHO, the reasons for seizures are somewhere else. But besides the design, what counts is solutions and downtime minimisation.
More importantly, as per my shameful experience of damaging aluminium threads, I really see stainless steel inserts as an advantage.

But that is only my own opinion in this given situation ;-)


Yes this is a hassle, BUT yes AP has probably has the best support out there! For me it totally makes up for it.


Cheers everyone!

Looking forward to share great things with my Mach2 ;-P


Carl Björk
 

Hi Tan, ( <-- I hope I got this right :') )

Seizing and cold welding are very different things.

Yes seizing is common, but to me it is with any metal, not just steel.
The lower the thread pitch is and the higher the diameter is the more likely it is to seize.
IMHO, assembly of metals is more complex than you think, it involves friction, dilation, wear, ...

I might be wrong, but I believe my situation is due to some sort of manufacturing defect. Perhaps tolerance issues with the insert.
There are many reasons for this to be possible to happen. And I am not interested into finding out what they are, what counts for me is having a working mount.

And boy, the support has been absolutely excellent and what mount did I choose, a Mach2, it is frustrating to wait, but in a way not so much:
I know I am gonna have THE mount. so that's what counts for me ;-)


M Hambrick
 

I agree with Cytan that a bronze insert would be ideal, but I also agree that stainless is better than aluminum. All it takes is one slipup with the aluminum threads and they are toast.

As for your predicament Carl, I am glad to hear that Astro-Physics is working on a solution.

Maybe I was looking at it wrong, or the angle of the camera distorted the view, but it looked in the picture that you sent like the shaft was cross threaded.

Mike


fernandorivera3
 

I have an AP 1200 GTO from July 2009 delivery & a few months ago I replaced it's original counterweight shaft adapter for the brand new one with the stainless steel insert. 
Of course when I threaded in my original counterweight shaft into the brand new adapter, after a few turns the thing got stuck on the insert threads. I'm glad I was able to separate the two as this actually happened immediately before taking off to a favorite dark sky site for the 1st time in a long while <thanks to Covid 19 concerns regarding long distance trips>.
Anyways if this problem of the shaft seizing up against the stainless steel insert happens again [especially if it becomes a repeating issue] then at the very least I still am holding on to my old school adapter, just in case...

Fernando


Carl Björk
 

The fact that the screwing went fine first then resisting then fine again and repeating this pattern is not consistent with cross threading.

Besides as I had read the below thread before hand, and I was REALLY cautious.
Also I must mention that the unthreaded part on the shaft seems to make it impossible to cross thread,

Last, I have "bush-gauged" measured the insert distance and found no indication of tilt whatsoever.

Carl


On Wed, Aug 10, 2022 at 12:23 AM, M Hambrick wrote:

I agree with Cytan that a bronze insert would be ideal, but I also agree that stainless is better than aluminum. All it takes is one slipup with the aluminum threads and they are toast.

As for your predicament Carl, I am glad to hear that Astro-Physics is working on a solution.

Maybe I was looking at it wrong, or the angle of the camera distorted the view, but it looked in the picture that you sent like the shaft was cross threaded.

Mike


Cheng-Yang Tan
 

HI Carl,
  I'm not a mechanical engineer so, I'm probably using the incorrect terms like cross threading. I think the correct terms should be seizing or galling.

  After reading quite a bit of info and talking to the engineers and techs who work with me, seizure or galling of stainless steel on stainless steel will happen because surprisingly, it is considered soft:



Any deformation of the stainless steel can cause seizing/galling. So even if the counterweight shaft was perfectly made and you're careful threading, it can still happen because of deformation. One solution is to use a harder steel or different material for the insert so that galling is prevented. My engineer colleague suggested silicon bronze for the insert, but other materials can work as well.

cytan


On Tuesday, August 9, 2022 at 05:09:19 PM CDT, Carl Björk <carl.bjork@...> wrote:


Hi Tan, ( <-- I hope I got this right :') )

Seizing and cold welding are very different things.

Yes seizing is common, but to me it is with any metal, not just steel.
The lower the thread pitch is and the higher the diameter is the more likely it is to seize.
IMHO, assembly of metals is more complex than you think, it involves friction, dilation, wear, ...

I might be wrong, but I believe my situation is due to some sort of manufacturing defect. Perhaps tolerance issues with the insert.
There are many reasons for this to be possible to happen. And I am not interested into finding out what they are, what counts for me is having a working mount.

And boy, the support has been absolutely excellent and what mount did I choose, a Mach2, it is frustrating to wait, but in a way not so much:
I know I am gonna have THE mount. so that's what counts for me ;-)


Harley Davidson
 

I use furniture spray wax on the threads every now and then. I keep it in my car as I use it to clean the inside and even bugs on the front of the cars bumper and hood. I let it set a minute or two on the threads and then wipe the threads off. I bet you could also use car wax although I've never tried it.

tony

On 8/9/2022 5:42 AM, Christopher Erickson wrote:

NEVER use WD-40 on ANY part of a telescope or mount. It is a PENETRANT, NOT a lubricant. It penetrates into everything. It dissolves and ruins real lubricants, it can ruin optical coatings, it can ruin circuit boards, and it can actually accelerate corrosion.

A drop of LUBRICANT in counterweight shaft threads is good. Cleaning dirty, contaminated threads with a toothbrush is good. And doing both is even more goodness. LOL. 

Using a [slightly oily] rag to clean shaft threads before assembly might do the trick as well. Place rag around threads, grab rag and threads and then "unscrew" the threads from the rag and your hand.

If your threads are really dirty with something that is really stuck to them, a metal brush and some Break-Free CLP might be required. Followed by the old "unscrew from an oily rag" trick. (Nod to Don Adams.)

Currently my favorite lubricant is Break-Free CLP (the older brown formula over the newer blue formula) but there are lots of good lubes out there for various applications. 

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   



fernandorivera3
 

Tony- furniture spray wax applied on your car?

Does it look like a haze after an application?

Even if it does I suppose it's easy to buff out.

Fernando