Altitiude Adjustment bolt very stiff

[Jm1973]

Hi All..

I'm having a problem with my EQ5 mount, and I'm not sure what to do about it.  One of the altitude adjustment bolts that are used to adjust and lock in the mount when doing polar alignment is extremely stiff.

One I can unscrew completely quite easily. The other feels very stiff whether I am tightening or loosening it, and it only seems to go a little way in or out. Luckily it is more or less in the vicinity of 51 degrees which is my latitude.

I am afraid to force it in case it strips the thread. Is there anything that can be done? Am I doing something stupid? The thread looks ok on the bolts itself.

It's the one on the right hand side in the pic. there are a couple of allan key bolts on the other side. Can I adjust anything with those?

 

 

Edited September 16, 2020 by Jm1973

[JamesF]

This is a common story and is really down to the design of the mount (most of the Skywatcher mounts, in fact).

The alt adjustment bolts push against a lug that tips the main mount body higher or lower, but at UK latitudes the face of the lug is at quite a steep angle to that bolt, making it quite awkward to turn.  In some situations, forcing the bolt has been known to bend the thread against the lug.  If you remove those two allen bolts the north side bolt should come away with the bracket and you'll be able to see what's going on.

The bolts aren't made of particularly high quality steel (which is why they bend) and people have found things improved by replacing the bolts with better quality ones, often with a decent knob on the end to give a better grip, though you still need to be aware of the risk of stripping the thread in the (relatively) soft aluminium of the mount body and try to avoid forcing things.

It may be worth removing the south side bolt completely just to check it isn't already bent (which makes it even harder to turn).

If you have an engineering background you can make modifications to the lug to make it work better, but I'm guessing that if you were of an engineering background you'd probably have had it in pieces already

James

[Budgie1]

The same happened to my EQ5 (bent bolt) and I replaced the bolts with the uprated versions. 

If you take the stiff bolt out then use plenty of lubricant, like WD40 or 3-in-1 oil, and let it soak in. This will limit any damage to the internal thread of the mount.

If you get the upgraded bolts then put grease on the ends of the bolts before you screw them into the mount and also put a dab of grease on where they connect with the lug on the mount. This will help protect the mount and make the adjustment a bit smoother.

[Peter Drew]

Removing the screw completely to check for damage and using lubrication are both good suggestions.  To these I would add, check the stiffness of the altitude axis by manually rocking the housing, in many cases this axis is overtightened by the manufacturer and is a significant contribution to the bent screw syndrome.   🙂

[Jm1973]

32 minutes ago, JamesF said:

This is a common story and is really down to the design of the mount (most of the Skywatcher mounts, in fact).

The alt adjustment bolts push against a lug that tips the main mount body higher or lower, but at UK latitudes the face of the lug is at quite a steep angle to that bolt, making it quite awkward to turn.  In some situations, forcing the bolt has been known to bend the thread against the lug.  If you remove those two allen bolts the north side bolt should come away with the bracket and you'll be able to see what's going on.

The bolts aren't made of particularly high quality steel (which is why they bend) and people have found things improved by replacing the bolts with better quality ones, often with a decent knob on the end to give a better grip, though you still need to be aware of the risk of stripping the thread in the (relatively) soft aluminium of the mount body and try to avoid forcing things.

It may be worth removing the south side bolt completely just to check it isn't already bent (which makes it even harder to turn).

If you have an engineering background you can make modifications to the lug to make it work better, but I'm guessing that if you were of an engineering background you'd probably have had it in pieces already

James

Thanks for the detailed reply. I'm reasonably competent at tinkering with things, but at the same time I don;t want to risk break anything on my newest toy without checking first.

[Jm1973]

11 minutes ago, Budgie1 said:

The same happened to my EQ5 (bent bolt) and I replaced the bolts with the uprated versions. 

If you take the stiff bolt out then use plenty of lubricant, like WD40 or 3-in-1 oil, and let it soak in. This will limit any damage to the internal thread of the mount.

If you get the upgraded bolts then put grease on the ends of the bolts before you screw them into the mount and also put a dab of grease on where they connect with the lug on the mount. This will help protect the mount and make the adjustment a bit smoother.

Thanks. This is very helpful. I'll take a look and consider getting the uprated versions.

[Jm1973]

2 minutes ago, Peter Drew said:

Removing the screw completely to check for damage and using lubrication are both good suggestions.  To these I would add, check the stiffness of the altitude axis by manually rocking the housing, in many cases this axis is overtightened by the manufacturer and is a significant contribution to the bent screw syndrome.   🙂

It seems to have play when I move the mount back and forth. But only within a certain angle. 

I'm afraid if I unscrew it it will get damaged. It's that stiff. I think I'll take it apart and see what I'm dealing with.

Thanks for taking the time to reply.

[Budgie1]

If you remove the North bolt you should be able to tilt the mount towards the South and then you can rock it to see how stiff the altitude axis is. It may also give you room to get some oil on the back of the stuck screw or see if it's bent. 

If it looks bent then try to straighten it before you unscrew it to avoid damage to the internal thread as the bent part of the screw goes through it. Also work the screw back & forth as you take it out and take it slow.

Edited September 16, 2020 by Budgie1