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Can't remove counterweight shaft
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Gavin Bray
I'm trying to unscrew the counterweight shaft on my 1200 but I'm having no luck. The last time I did this was about 2 years ago.
Firstly, can someone confirm, if looking up the shaft to the dec housing, I need to rotate the shaft counter clockwide to undo it? Can someone offer some suggestions for how I should remove it? I've given it a few gentle taps with the palm of my hand but didn't want to use any more force. I see that the black section at the bottom of the dec housing has an access hole but I'm not sure if this is relevant and I couldn't see anything in the manual. Thanks Gavin |
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MrGrytt
Yes counterclockwise, and use a strap wrench if necessary. Get them at Sears.
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Harvey --- In ap-gto@..., "gavingbray" <gavbray@...> wrote:
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terrylo <terry@onset.com>
Gavin:
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I have "been there - done that." Strap wrench (from Sears) did the trick to free the shaft. But it happened again after setting up in the sun on a warm day with a following cold night After I got the shaft free, I cleaned the threads on both shaft and socket and then applied a layer of carnuba wax to the threads. I let it dry, ran the shaft on and off a few times and wiped off the residue. It has not bound-up since. (This was suggested by a fellow mount owner.) Terry --- In ap-gto@..., "gavingbray" <gavbray@...> wrote:
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Poschinger Konstantin v. <KPoschinger@...>
Hi,
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put a counter wight on the shaft an turn, so you will get it loose. Konstantin Konstantin v. Poschinger Hammerichstr. 5 22605 Hamburg 040/8805747 0171 1983476 Am 02.04.2010 um 05:32 schrieb gavingbray: I'm trying to unscrew the counterweight shaft on my 1200 but I'm having no luck. The last time I did this was about 2 years ago. |
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Roland Christen
In a message dated 4/1/2010 10:34:00 PM Central Daylight Time,
gavbray@... writes: Can someone offer some suggestions for how I should remove it?Heat the shaft and aluminum adapter with hotwater. Tap it with a plastic hammer. Use a strap wrench if need be. You can also unscrew the adapter along with the counterweight shaft if you cannot get the shaft out easily. Rolando |
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Roland Christen
In a message dated 4/2/2010 12:04:07 PM Central Daylight Time,
J.Zeglinski@... writes: If that (black ring) adapter starts to unscrew, we are in an evenAluminum expands at a higher rate than stainless, so if the aluminum adapter comes off, just place it in hot water and it will expand and loosen up. Rolando |
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Roland Christen
In a message dated 4/2/2010 12:57:50 PM Central Daylight Time,
howard@... writes: Whatever a person uses, keep in mind that the axes are being held inJust to clarify, the counterweight shaft is attached directly to the housing, not the worm shaft. Therefore no possibility of messing up the gears thru rotation of the counterweight shaft. What Howard is worried about is to not lock the RA axis with the counterweight shaft horizontal and then pulling down on the shaft, because this puts stress on the worm wheel teeth. Rolando |
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Konstantin's suggestion of using a counterweight as your "gripping tool"
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is so simple and obvious that it caused me to give myself a dope-slap for not immediately thinking of it. The purpose of my post is to tell you about the hole you described in the side of the black counterweight shaft adapter. This hole is there so that the adapter can be tightened onto the body of the declination axis housing. If your shaft is really stuck, you may find that the adapter will break loose first instead of the shaft. If that happens, find a 1/4" rod (the hole is drilled 17/64") or use a large Phillips screwdriver with a 1/4" shaft to tighten the adapter back up and then use it as a holdback on the adapter. You may need to grow an extra set of hands! ;^) Mag. 7 skies! Howard Hedlund Astro-Physics, Inc. 815-282-1513 -----Original Message-----
From: ap-gto@... [mailto:ap-gto@...] On Behalf Of Poschinger Konstantin v. Sent: Friday, April 02, 2010 3:42 AM To: ap-gto@... Subject: Re: [ap-gto] Can't remove counterweight shaft Hi, put a counter wight on the shaft an turn, so you will get it loose. Konstantin Konstantin v. Poschinger Hammerichstr. 5 22605 Hamburg 040/8805747 0171 1983476 Am 02.04.2010 um 05:32 schrieb gavingbray: I'm trying to unscrew the counterweight shaft on my 1200 but I'mhaving no luck. The last time I did this was about 2 years ago. housing, I need to rotate the shaft counter clockwide to undo it? want to use any more force. access hole but I'm not sure if this is relevant and I couldn't see anything in the manual.
[Non-text portions of this message have been removed] ------------------------------------ To UNSUBSCRIBE, or for general information on the ap-gto list see http://groups.yahoo.com/group/ap-gtoYahoo! Groups Links |
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John
Gavin,
You can make an "emergency" strap wrench using a heavy, soft rubber electric cord, wrap several turns around the shaft, grab the loose ends where they come off the shaft and twist. You might also try heating the joint with a hair dryer, the aluminum housing should expand faster than the stainless shaft. Good luck, John |
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Joe Zeglinski
Howard,
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If that (black ring) adapter starts to unscrew, we are in an even bigger mess, trying to remove it, without leverage and a third arm, from a stuck bar! I would recommend the rubber strap wrench, since it is less likely to mark, or worse, scratch, a groove in the bar from the counterweight locking pin, if it looses its grip. If that happens, slipping the weight up & down will become difficult in the future, because of the existing tight smooth fit. The counterweight is a good idea as a first attempt, for a "slightly" stuck shaft. TWO rubber strap wrenches would be better - left & right sides - for "evenly balanced" leverage. Otherwise, torquing one wrench, would give problems with rocking the mount, or having the RA axle move as you struggle with it. On a tripod, you would wouldn't want to be pressing down on the shaft - dangerous to the user and the mount. If that still doesn't work, rotate the RA until the shaft is inverted, and spray some WD-40 between the threads and the black ring, to loosen the grip, and retry using either of the two methods. The WD-40 is a good de-icer, which is probably the cause here. Wash off (if there is any snow or water nearby) any remaining WD-40, which is a "mildly" corrosive lubricant - though perhaps not corrosive to the anodized ring (just keep it off the counterweight "plastic" knob or mount paint, DEC axle !). ********* Howard - while we are on this subject, I have been putting off asking a "related question". WHY does AP put so many fine threads on the counterweight shaft and on the PAS scope? It must take about 30 turns and somewhat too much time, to install and remove these, sometimes with cold hands, for us "portable users". Surely, a bayonet approach, or at least "Mason Jar Lid" threads (maybe even 2 to 3 mm thick ones, and about 8 or 10 turns per inch), would have done just as well. Of course, AP may be concerned about all that counterweight, on thin threads, might just strip off the threads and send the OTA flying (if the OTA is huge), so it needs such a huge number of threads as backup. But a more reasonable number of much thicker thread might have sufficed, especially for the PAS threads, which are not weighted. Joe ----- Original Message -----
From: "Howard" <howard@...> To: <ap-gto@...> Sent: Friday, April 02, 2010 10:23 AM Subject: RE: [ap-gto] Can't remove counterweight shaft Konstantin's suggestion of using a counterweight as your "gripping tool" |
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Anthony Ayiomamitis <anthony@...>
O/H chris1011@... έγραψε:
Rolando, Aluminum expands at a higher rate than stainless, so if the aluminumGoing back to my older C14 days, there were times at the end of the session where I would have a hard time removing some of the accessories (the 2" SCT diagonal comes especially to mind). I now have a similar problem with my Mewlon adapter which fits between the CCD camera and the reducer/flattener. I have noticed that these problems are especially acute in colder weather but also do surface during much milder weather (I just spent a very difficult ten minutes removing the Mewlon adapter). What is the best way to face these problems? Get replacement accessories (perhaps from a different manufacturer)? Have some strategy in-doors? Anthony.
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That's why the inner sleeve and the locking pin are made of brass. They
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might be able to leave a visible mark, but they certainly cannot scratch much of a groove in stainless steel. A rubber strap wrench is great if you have one handy, but I wouldn't leave a remote observatory and drive 20 miles to the nearest Home Depot to buy one (or two) without first trying the counterweight. For the future, this might be a good opportunity to remind people that there is no reason in the world to over-tighten the counterweight shaft! Whatever a person uses, keep in mind that the axes are being held in position by the worm gears on the worm wheels. When a worm drive is removed, the corresponding axis turns very freely. It is therefore possible to apply a tremendous amount of torque against the worm drive by hanging on a wrench in an inappropriate manner. Do not use your wrenches in a way that will stress the worm drive! I spent 7 years as a sprinkler pipe-fitter back in the day when fire sprinkler systems were almost entirely composed of screwed pipe. The best way to break a threaded connection loose without applying undue stress where it is not wanted is to use opposing wrenches - one to hold back, the other to turn what is to be loosened. The wrenches should be as close to each other as possible - side-to-side - while still allowing room for one hand on each wrench handle. The wrench handles should also be nearly parallel. Avoid the temptation to have the hold back sticking out on one side and the moving wrench sticking out on the other. If possible, arrange things so that the two wrenches are straight in front of you with one hand on each wrench, and your hands no more than a few inches apart. You will be able to apply tremendous torque to the stuck joint while putting almost no stress on the rest of the system. Trust me on this method! The thread specs pre-date me by a long shot. I can't tell you why they were chosen, but it would be a nightmare in terms of cross or backward compatibility to change them now. Mag. 7 skies! Howard Hedlund Astro-Physics, Inc. 815-282-1513 ________________________________ From: ap-gto@... [mailto:ap-gto@...] On Behalf Of Joseph Zeglinski Sent: Friday, April 02, 2010 12:03 PM To: ap-gto@... Subject: Re: [ap-gto] Can't remove counterweight shaft Howard, If that (black ring) adapter starts to unscrew, we are in an even bigger mess, trying to remove it, without leverage and a third arm, from a stuck bar! I would recommend the rubber strap wrench, since it is less likely to mark, or worse, scratch, a groove in the bar from the counterweight locking pin, if it looses its grip. If that happens, slipping the weight up & down will become difficult in the future, because of the existing tight smooth fit. The counterweight is a good idea as a first attempt, for a "slightly" stuck shaft. TWO rubber strap wrenches would be better - left & right sides - for "evenly balanced" leverage. Otherwise, torquing one wrench, would give problems with rocking the mount, or having the RA axle move as you struggle with it. On a tripod, you would wouldn't want to be pressing down on the shaft - dangerous to the user and the mount. If that still doesn't work, rotate the RA until the shaft is inverted, and spray some WD-40 between the threads and the black ring, to loosen the grip, and retry using either of the two methods. The WD-40 is a good de-icer, which is probably the cause here. Wash off (if there is any snow or water nearby) any remaining WD-40, which is a "mildly" corrosive lubricant - though perhaps not corrosive to the anodized ring (just keep it off the counterweight "plastic" knob or mount paint, DEC axle !). ********* Howard - while we are on this subject, I have been putting off asking a "related question". WHY does AP put so many fine threads on the counterweight shaft and on the PAS scope? It must take about 30 turns and somewhat too much time, to install and remove these, sometimes with cold hands, for us "portable users". Surely, a bayonet approach, or at least "Mason Jar Lid" threads (maybe even 2 to 3 mm thick ones, and about 8 or 10 turns per inch), would have done just as well. Of course, AP may be concerned about all that counterweight, on thin threads, might just strip off the threads and send the OTA flying (if the OTA is huge), so it needs such a huge number of threads as backup. But a more reasonable number of much thicker thread might have sufficed, especially for the PAS threads, which are not weighted. Joe ----- Original Message -----
From: "Howard" <howard@... <mailto:howard%40astro-physics.com> > To: <ap-gto@... <mailto:ap-gto%40yahoogroups.com> > Sent: Friday, April 02, 2010 10:23 AM Subject: RE: [ap-gto] Can't remove counterweight shaft Konstantin's suggestion of using a counterweight as your "grippingtool" is so simple and obvious that it caused me to give myself a dope-slap[mailto:ap-gto@... <mailto:ap-gto%40yahoogroups.com> ] On Behalf Of Poschinger Konstantin v.<http://groups.yahoo.com/group/ap-gtoYahoo> ! Groups Links <http://groups.yahoo.com/group/ap-gtoYahoo> ! Groups Links |
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Joe Zeglinski
Howard,
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The threads predate me as well. However, I thought it might be possible to offer the black DEC shaft housing ring (we have alluded to here), and a different shaft, with the Mason Jar threads. Similar pair for the PAS retrofit, if it were a desirable item. That way, there would be no "production" changes required, as this would be a retrofit kit "accessory", relatively easily user installable. My question was more of a "why not" - don't see the purpose of so many fine threads, from an engineering viewpoint. There must have been a good reason to begin with. Perhaps just overkill safety in numbers. Otherwise, not a pressing issue. Joe ----- Original Message -----
From: "Howard" <howard@...> To: <ap-gto@...> Sent: Friday, April 02, 2010 1:57 PM Subject: RE: [ap-gto] Can't remove counterweight shaft
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dannysperry
It's for this reason that I always carry 2 large rubber bands with me (about 1/8" thick and 1/2" wide). The counterweight shaft and/or the Takahashi adapters are always getting stuck. I just place the rubber bands on the two parts and twist. They can grip much better than my hands alone can.
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Once you get it out, you may want to add a very small amount of grease or WD-40 to the threads. Best, Danny --- In ap-gto@..., "gavingbray" <gavbray@...> wrote:
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paulduncanauto@...
I have used a leather belt and a stick one morning away from home. I used the counterweight to twist the shaft and held the collar with my belt wrench..worked great! I did notice some oxidation (white film) on the shaft. Cleaned it with WD-40... Butter smooth now.
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Clear Skies Paul -----Original Message-----
From: John <elkridgeastro@...> To: ap-gto@... Sent: Fri, Apr 2, 2010 8:50 am Subject: [ap-gto] Re: Can't remove counterweight shaft Gavin, You can make an "emergency" strap wrench using a heavy, soft rubber electric cord, wrap several turns around the shaft, grab the loose ends where they come off the shaft and twist. You might also try heating the joint with a hair dryer, the aluminum housing should expand faster than the stainless shaft. Good luck, John [Non-text portions of this message have been removed] |
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Hi guys
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I have been following this thread on Dec. counter weight shaft seizing problem and I believe there is a misconception as to the main cause of the Dec counter wt shaft jamming on the Dec housing fitting. I believe the primary reason the shaft can seize to the housing adapter has little or nothing to do with the threads or thread design. The pin end of the Dec shaft has a relatively large flat shoulder that mates up with a corresponding large surface area flat on the aluminum housing adapter. When you spin the shaft on and these two relatively large surface area mating surfaces connect, there can be considerable friction generated; especially if one spins the shaft on agressively. The problem may be aggrivated if you couple this with a large temperature differential (warm to cold)between assembly temp and dis-assembly temp ie. warm afternoon set up cold early morning take down. The reason we can get what is in effect a "shrink fit" is not so much the contracting metal housing fitting causing the threads to seize but the cooling of the metal Dec shaft causes the shaft to shrink in length. The threaded pin on the end of the Dec shaft shortens and pulls the two mated metal to metal surfaces tighter together. A change in temp will have a far greater effect on the length of a metal bar than it will on is diameter. Simple physics! If the threads really were the problem, then one would have difficulty un-threading the shaft the entire length of the threaded pin. My experience has been that once the flat mated surface connection is broken, the shaft spins off easily. As to what is the answer to this, there are of course several and a number have been proposed here. Additional options are: 1. Grease the flat mating surfaces as well as the threads. 2. Don't spin the shaft up tight. It only needs to be made up slightly hand tight. I found this works for me. Finally, I work in the oil industry and the type of threaded connection used on the Dec counter Wt shaft and Dec housing is used quite extensively in oilfield equipment, especially in sucker rod pumping equipment. We count on the fact that the flat mating surfaces stay tight for this equipment to work. Cheers everyone Don --- In ap-gto@..., "Joseph Zeglinski" <J.Zeglinski@...> wrote:
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Gavin Bray
Thanks everyone for all your suggestions. I purchased a strap wrench and turned but this caused both the shaft and black adapter to turn so I inserted a screw driver into the adapter hole as Howard suggested, tighted it up first, and then left it in place while I turned the shaft and voila, I was able to undo the shaft!
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I only hand tightened last time but I'll be even more careful next time. Regards Gavin --- In ap-gto@..., "dannysperry" <danny@...> wrote:
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Joe Zeglinski
Hi Don,
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While you are absolutely correct about the real cause of shaft stick, as you can read, my (secondary) point was about having so many threads on the shaft and the PAS, that it takes about 30 turns to get it on or off. Doing this in cold weather was even more discomforting. I really do not see the point of so many fine threads, and felt that it could have been done better. I assume it is just easier to fine thread a shaft on a lathe, which is quite common, than having to use a shaped tool to make large and sparse Mason Jar type threads, even on a CNC computer programmed lathe or milling machine.. As for the "stiction", I mentioned this problem to AP about a year ago, and suggested that adding a thin Teflon washer to the flat at the base of the shaft threads, would resolve the problem of locked threads. This would cost pennies to stamp out to the diameter of the shaft. I also mentioned that although grease could be applied, I would prefer not to have ANY grease where it could be touched by a hand, and transferred to optics or other equipment. That is fine for "permanently" set up mounts, but definitely bad for portable ones, where contact can be made with greasy threads twice in one session. Joe ----- Original Message -----
From: "Don" <jockey_ca@...> To: <ap-gto@...> Sent: Friday, April 02, 2010 10:18 PM Subject: [ap-gto] Re: Can't remove counterweight shaft Hi guys |
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Hi Joe
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Yes I see your point about the fine threads and the grease. I personally get by by just barely snugging up the shaft to the Dec housing adapter. With regard to thread design, It looks like the connection is a 1" American Unified National Fine(UNF)standard bolt thread. The corresponding Unified National Coarse (UNC)thread for that size pin is 8 threads per inch (TPI). I think if AP used that coarse a thread, users would have problems keeping the connection tight. The pitch of the threads would be so steep that the connection would tend to come loose in use unless the shaft was tightened with a set of wrenches(more force applied to the flat mating surfaces). The problem would only get worse as more counter wts were added to the Dec axis and horizontal loading increased. I don't think that would make users happy. Have a great weekend Joe Don --- In ap-gto@..., "Joseph Zeglinski" <J.Zeglinski@...> wrote:
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Joe Zeglinski
Thanks Don,
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You make a very good point about using course threads. I hadn't considered that problem. Joe ----- Original Message -----
From: "Don" <jockey_ca@...> To: <ap-gto@...> Sent: Saturday, April 03, 2010 12:49 AM Subject: [ap-gto] Re: Can't remove counterweight shaft Hi Joe |
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