Astro Engineering MegaWedge

[michael8554]

What is needed to complete the Az adjustment on this upside-down view of an AE MegaWedge?

I'm guessing that the sideways adjustment isn't feed via the threads on the stub?

So perhaps a starwheel as shown on the Alt adjustment, but with a shoulder or washer that runs in the groove in the Az Index bracket?

Michael

[Davey-T]

I think that's just to fix it to the tripod not for adjustment.

Dave

[michael8554]

Hi Dave

The threaded stub protrudes from a large ally cylinder.

This cylinder has a horizontal threaded rod passing through it and the wedge cheeks.

Turning that rod moves the cylinder in Az.

The Az Index Bracket is attached to the pier at the other end from the slot., so the wedge , mount, and OTA have to move in Az relative to the fixed Az Index Bracket

But how is the Index Bracket attached to the threaded stub so that the threads aren't damaged by the sideways thrust?

Michael 

[Davey-T]

Starwheels here.

Dave

https://www.goodhanduk.co.uk/Catalogue/Standard-Parts/Star-Palm-Grips-Wing-Grips-Knobs/Star-Palm-Grips

[symmetal]

I have an AE wedge (think it's the same model) along with a matching pier adaptor plate which has the forked piece welded to it. The threaded stub is just fixed to the fork by a plain nut and washer. Mine doesn't have the recessed channel with the slot. You loosen off the fixing bolts holding down the wedge to the pier slightly, the outer bolts run in slotted holes to allow adjustment. There is sideways force applied to the threaded stub while turning the azimuth threaded rod but it's not enough to cause any issues. When the azimuth is correct you tighten up the bolts holding the wedge to the pier mounting plate. On a permanent pier you hopefully only have to do this once. If you're setting up every time it would probably cause wear on the stub but that doesn't matter really as the stub serves no real purpose once the bolts holding the wedge to the pier are tightened. It's only purpose is to allow fine adjustment. Once the main wedge bolts are tightened you could turn the azimuth adjustment threaded screw slightly just to remove the constant sideways force on the stub.

I only had this setup for a short time until I changed the scope and mount for imaging. The LX200 on the wedge wobbled very easily with a slight wind or vibration and would take a long time to settle down after so was very frustrating to use for imaging.

Alan

[LightBucket]

I had this wedge a while ago, and the bit you ask about fits to the AE Adapter plate which goes on top of their pier, there is a bit protruding from the plate with a long slot in, the small bolt goes through that and enables adjustment from side to side via the hand wheel of bolt on the side of the wedge...

here is a pic...

 

[michael8554]

Thanks Alan

I'm really surprised it's just a washer and nut, seems really cheapskate compared to the rest of the engineering.

Hi Lightbucket, the Az Index Bracket serves the same purpose as the AE Adapter plate, and I've already explained how the Az adjustment works - but you still haven't told me how the threaded stub is secured........... !!

Michael

 

[michael8554]

Hi Dave

Thanks for the link to the knobs, the boss on an M6 one nicely fits the recessed channel in the Az Index Bracket.

Michael

[LightBucket]

7 hours ago, michael8554 said:

Thanks Alan

I'm really surprised it's just a washer and nut, seems really cheapskate compared to the rest of the engineering.

Hi Lightbucket, the Az Index Bracket serves the same purpose as the AE Adapter plate, and I've already explained how the Az adjustment works - but you still haven't told me how the threaded stub is secured........... !!

Michael

 

It’s just secured with a large washer and nut....how else would a bolt be secured....

[michael8554]

Thanks Lightbucket, you finally got there.

Yes, a washer and nut, why didn't I think of that?

Because it's such a poor solution.

The Meade wedges, although otherwise poorly engineered, at least have a plain steel pin running in the groove.

Dave's star knob, with the plain boss running in the channel, offers a better solution.

 Alan suggests wear on the thread may not be an issue for a permanent pier, but would cetainly be for somene who tears down and sets up every session.

Michael 

 

[LightBucket]

2 hours ago, michael8554 said:

Thanks Lightbucket, you finally got there.

Yes, a washer and nut, why didn't I think of that?

Because it's such a poor solution.

The Meade wedges, although otherwise poorly engineered, at least have a plain steel pin running in the groove.

Dave's star knob, with the plain boss running in the channel, offers a better solution.

 Alan suggests wear on the thread may not be an issue for a permanent pier, but would cetainly be for somene who tears down and sets up every session.

Michael 

 

There is no real wear on that nut, I personally would not want to be putting that wedge up and down all the time, but if you have to, then the nut will still not be an issue in my opinion....

[michael8554]

Thanks Lightbucket,

The teardown scenario was only to exaggerate why the threaded pin was pants engineering, I'll go with a washer and nut for my pier-mounted setup for now.

Thanks everyone for the responses.

Michael

[michael8554]

I've discovered that the threads on the wedge are all M8, except for this threaded pin.
It's 1/4-20, same as a tripod - bizarre !
I couldn't find a nice star knob in this thread, only a wing nut.
I made a rectangular slider to fit the channel in the Index Bracket:

 

Further poor engineering - the tilt plate is a loose fit between the cheeks, so when everything is tightened the PA moves about 5 arcmins - yes 15mm steel does bend !
I filled the gaps with suitable thickness washers, now not perfect but much better.

The wedge is certainly much better than the standard Meade wedge, adjustment is much more certain, especially Az has only a small amount of backlash.

Michael

[LightBucket]

1 hour ago, michael8554 said:

I've discovered that the threads on the wedge are all M8, except for this threaded pin.
It's 1/4-20, same as a tripod - bizarre !
I couldn't find a nice star knob in this thread, only a wing nut.
I made a rectangular slider to fit the channel in the Index Bracket:

 

Further poor engineering - the tilt plate is a loose fit between the cheeks, so when everything is tightened the PA moves about 5 arcmins - yes 15mm steel does bend !
I filled the gaps with suitable thickness washers, now not perfect but much better.

The wedge is certainly much better than the standard Meade wedge, adjustment is much more certain, especially Az has only a small amount of backlash.

Michael

I had to make that same mod on mine with the washers, it worked a treat..