21 replies to this topic

[ribuck]

Hi All,

 

I've been thinking for a while about replacing my the spider on my 10" Quattro and i don't want a direct "like for like" replacement in terms of the mechanical design, as i think the secondary design is really bad in terms of accuracy and fine adjustment.

 

So i did what everyone would do and set about googling, and i came across what looks like a unique design on Ali Express.  

 

I particularly like the way the secondary is threaded all the way through to the mirror holder to give a much more rigid design and the way it's had holes tapped in increments so you get a good idea for rotation position.  Then looking further at the rotation, it has fine tuning like that of Azimuth mount with the central peg, which looked interesting.

 

My only concern is having to remove the secondary mirror and then glue it to the new secondary holder.

 

I just wondered if anyone else has used on of these  spiders ?  

 

 

 

 

Many Thanks,

Rich.

Edited by ribuck, 24 May 2025 - 12:08 PM.

[havasman]

Not familiar with Ali Express products, preferring established local small business options when available.

 

But I replaced my XT10i's upper end with Astro Systems spider, secondary holder and 1/16th wave secondary so I could add their best in class dew control system. That scope is heavily modified and this one brought the greatest optical gain of any. Very highly recommended.  https://www.astrosys...iz/products.htm

[nof]

I’d like to hear how this works out if you try it. I’ve got a 12” flex tube and the Astro systems spider is too deep

Hi All,

I've been thinking for a while about replacing my the spider on my 10" Quattro and i don't want a direct "like for like" replacement in terms of the mechanical design, as i think the secondary design is really bad in terms of accuracy and fine adjustment.

So i did what everyone would do and set about googling, and i came across what looks like a unique design on Ali Express.

I particularly like the way the secondary is threaded all the way through to the mirror holder to give a much more rigid design and the way it's had holes tapped in increments so you get a good idea for rotation position. Then looking further at the rotation, it has fine tuning like that of Azimuth mount with the central peg, which looked interesting.

My only concern is having to remove the secondary mirror and then glue it to the new secondary holder.

I just wondered if anyone else has used on of these spiders ?






Many Thanks,
Rich.

[Jon Isaacs]

 

I particularly like the way the secondary is threaded all the way through to the mirror holder to give a much more rigid design and the way it's had holes tapped in increments so you get a good idea for rotation position.

 

What I see:

 

Two plates, the upper hub and the lower mirror holder. The upper plate is threaded, the lower plate is not. If it were, the secondary tilt could not be adjusted.  

 

The mirror holder can be rotated just as a normal secondary.  The fine adjustment is nice but it looks difficult to access.. Not a good place to drop a wrench.

 

What is the material? I'm guessing aluminum. The vanes appear to be welded to the hub. 

 

Jon

[ribuck]

Hi Jon,

 

yes they are aluminium, and for the secondary rotation I was thinking about replacing the grub screws with some little knurled screws so that tools would not be required.

[havasman]

When I ordered the replacement system from Astro Systems, Randy contacted me directly to tell me his gear would not work in the XT10i as it was too long to match up to the focuser location. I appreciated that but told him I had used his print on the website and determined that all I needed to do was drill new spider mounting holes that would allow all the stack-ups to work. The prints were accurate. The accommodation worked. As anticipated the central threaded shaft of the secondary holder extends about 0.7mm above the aperture but that is not any concern. 

 

So if you are capable of simply drilling new spider mounting holes accurately and can layout the installation using the prints you may be able to overcome apparent obstacles to the installation of this superior system.

Edited by havasman, 24 May 2025 - 03:24 PM.

[ribuck]

Not sure why you feel it’s a superior design. Having a strange deep cup, and then needing to fill it with polystyrene / foam to support the mirror seems like a really bad design as that polystyrene / foam will degrade over time.  if I’m honest it just looks like someone made a secondary holder out of a few bits of scrap metal and some nuts & bolts in their garden shed and then spray painted it.

 

There is no real innovation happening here, they are just using thicker, stiffer materials and old school designs.

 

The problem is that the spider vanes are tensioned against the scopes tube itself which can flex slightly.  If you go with a single piece cnc spider you have the extra rigidity of the outer ring which attaches to your tube, thus strengthening the whole end of the tube, and because it’s  single piece you know it’s perfectly central which cannot be said of a 4 vane spider which has to be screwed to the tube, where you have to ensure the bolt is tensioned exactly the the same or it will throw out the central axis.

Edited by ribuck, 24 May 2025 - 04:03 PM.

[ribuck]

What I see:

 

Two plates, the upper hub and the lower mirror holder. The upper plate is threaded, the lower plate is not. If it were, the secondary tilt could not be adjusted.  

 

The mirror holder can be rotated just as a normal secondary.  The fine adjustment is nice but it looks difficult to access.. Not a good place to drop a wrench.

 

What is the material? I'm guessing aluminum. The vanes appear to be welded to the hub. 

 

Jon

No welding, appears to be a single piece of cnc’d alluminium

[Asbytec]

I think it's an interesting design. It looks sturdy. The spider vanes attach to an end ring mounted on the upper tube opening. How is the central bolt mounted? Hard to see into that depression.

As for regluing the Secondary, how is it attached to the holder? Tape? If so, regluing is easy. Cut the diagonal mirror off and use three spots of silicone glue and tooth picks or match sticks to provide uniform separation from the plate.

Edited by Asbytec, 24 May 2025 - 11:12 PM.

[Jon Isaacs]

No welding, appears to be a single piece of cnc’d alluminium

 

That's what I thought at first and that may be correct. But looking at the joint, it appears to me that there's an undercut typical of a weld. It would have to be ground and polished.

 

Jon

[ribuck]

Hi Jon,

 

I'm just trying to find the imagine online, as there was an image showing it being milled out of of a block of aluminium, but the question is, how much do i trust that from AliExpress.

 

In terms of the mirror replacement, removing and gluing the mirror is not the bit that worries me, it's the the gluing it in the correct position that worries me.

Edited by ribuck, 25 May 2025 - 02:57 AM.

[ribuck]

I found some much better pictures on Ebay, so i think i'll buy form ebay then at least i have some protection.

 

 

Ebay Link

[ribuck]

I think it's an interesting design. It looks sturdy. The spider vanes attach to an end ring mounted on the upper tube opening. How is the central bolt mounted? Hard to see into that depression.

As for regluing the Secondary, how is it attached to the holder? Tape? If so, regluing is easy. Cut the diagonal mirror off and use three spots of silicone glue and tooth picks or match sticks to provide uniform separation from the plate.

I have some very strong 3m double sided tape which would probably do the job nice to reconnect.  It's just ensuring the position of the mirror is correct when i replace it.  That said if draw around the current holder with a sharpie on the back of the mirror then it should give me a good idea for the position.

[astrobug BE]

I use this spider on my 200 F5 scope since 2025. Can't complain about it for the price. 

There are several holes so you can position the vanes under your focuser or turned 45°.

This was the 1st test, on the left with 6nm Ha filter and the right one with a L3 filter. Both filters are from Astronomik.

 

Edited by astrobug BE, 25 May 2025 - 04:58 AM.

[ribuck]

I use this spider on my 200 F5 scope since 2025. Can't complain about it for the price. 

There are several holes so you can position the vanes under your focuser or turned 45°.

This was the 1st test, on the left with 6nm Ha filter and the right one with a L3 filter. Both filters are from Astronomik.

 

info newton.jpg

Thanks for the feedback, How you you find it's stability ?  does it hold collimation well ?  How is the mirror rotation, is it a bit fiddly ?

[astrobug BE]

I use my scopes in an observatory and could not see any change in collimation before and after the flip or during modeling the mount. About the rotation, its for the real fine tuning. It can be done on the bench. Once set no need to adjust in on the mount. Its an improvement over the one you have now. I don't understand why SW don't use that kind of spider from the start. 

[ribuck]

Well i've ordered one which will take about 2-3 weeks to arrive, so i'll see how i get on with it.

 

I did however pick up a good tip today. Apparently the flares around the star in between the diffraction spikes can apparently be removed by covering the spikes with thin strips of velour either side of each spider arm, apparently.

 

So when i the secondary Mirror I'm going to Re-Flock my tube and use some of the flocking material on the vanes to see if it makes any difference.

Edited by ribuck, 26 May 2025 - 12:47 PM.

[Tom Stock]

It looks nice. I don't see anything special about the secondary holder other than the fact that it is CNC machined. The fine adjustment seems unnecessary.

 

I'm not a huge fan of the thickness of the vanes, or the fixed diameter of the outer spider ring because it could only be used in very specific tubes, but otherwise it looks to be made very well.

[ribuck]

Well just on the CNC part alone it’s pretty much half the price of buying one from the usual Astro retailers in my country, so if nothing else, the cost saving is worth it.

[ribuck]

No bad delivery times, as it looks like i should receive the new spider in the next 2 days. So look like 8-9 days delivery time from China. Hopefully will get it by Friday so i can fit it this weekend and post a review.

[ribuck]

Well the spider arrived as expected so i'll do a review of it over the coming weeks, but it's going to be hard to test as i'm at 55 North, so it doesn't really get dark, even at midnight, the sky is still very bright.

[ribuck]

Here a quick initial impression video if anyone is interested.

 

https://youtu.be/GwbJf5zaup0

Edited by ribuck, 07 June 2025 - 10:12 AM.