Crayford or Rack and pinion for 80ED focuser replacement

[Vox45]

Hello all,

I fiddled with the stock focuser that comes with the SW 80ED and followed a lot of tutorial on how to make it better, less slippage and so on, but I still have issues when using an electric focuser to bring the tube back in when there is load on the focuser (camera and FF/FR) 

In the meantime I've decided to construct my own little Arduino focuser (MyfocuserPro) so now I am thinking of changing the stock focuser for a better one ...

Should I go for a Crayford type focuser or a rack and pinion focuser ? I think that rack and pinion make more sens as I can set the backlash in the autofocuser software and that would eliminate the slippage issue (unless there is too much weight and then the motors would skip steps but that is another issue). It seems that most people use Crayford focuser,  why would a rack and pinion not be worthy of consideration ?

Any thoughts on this ?

Edited December 26, 2019 by Vox45

[johninderby]

One of the good crayfords such as a Baader Steeltrack, Moonlite or if the budget allows a FeatherTouch would be my choice.

I’ve tried the cheaper R&Ps and found that they aren’t as smooth although they do hold weight well.

Best of all would be a FeatherTouch R&P but they are very expensive and more suited to a bigger scope.

Edited December 26, 2019 by johninderby

[Adreneline]

25 minutes ago, Vox45 said:

Crayford type focuser or a rack and pinion focuser ?

I went for a Baader DIamond Steeltrack and it transformed my ED80DS-Pro. Prior ro fitting the Steeltrack focussing was very hit and miss and completely non-repeatable. To make things worse at high dec setting the drawer tube would just slide out of the OTA complete with camera, focus wheel, etc., resulting in hours of duff out of focus subs. The Baader was easy to fit and cured all the problems.

HTH

[Ronclarke]

I went for a Moonlite, 2 reasons, 2 accessory shoes and rotation! Never looked back!!

 

[johninderby]

Rotation is pretty well standard with all crayford focusers. The Baader also has 5 mounting posrions for accessories so more than one finder shoe can be used. 

[joe aguiar]

If your doing imaging then those stock focuser are not good enough. U need either moonlight or feather touch focuser. 

They are not cheap tho i paid $713 for my moonlight on my takahashi 102 TSA.

For visual it might be ok without a camera but even some 2 inch ep give those regular stock focuser slippage. 

It's kinda normal to upgrade the focuser if u do ap.

Joejaguar 

[tooth_dr]

4 minutes ago, joe aguiar said:

If your doing imaging then those stock focuser are not good enough. U need either moonlight or feather touch focuser. 

It's kinda normal to upgrade the focuser if u do ap.

Joejaguar 

I’m going to say no here, I think there is little wrong with the stock ed80 crayford focuser.  It can handle a FR, EFW and CCD.  It’s on the limit but ‘good enough’

[johninderby]

The Baader is more durable than the Moonlite and having owned both would go for the Baader on an 80mm scope. 

[JamesF]

I've been very happy with the Steeltrak focusers.  I've not used the new "Diamond" version, but I've always thought the earlier model was very well put together.  I think I have three of them in use now.  I also have an aftermarket Revelation R&P focuser which, to be fair, is not bad at all.  Unfortunately the market seems to have disappeared for "reasonably-priced" aftermarket R&P focusers.  Last time I looked there seemed to be very few available for less than several hundred pounds, which wasn't the case, say, five or six years back.

One of the particularly nice features of the Steeltrak if you're intending to motorise it is the built-in gear ring on the focuser spindle.

James

[JamesF]

50 minutes ago, tooth_dr said:

I’m going to say no here, I think there is little wrong with the stock ed80 crayford focuser.  It can handle a FR, EFW and CCD.  It’s on the limit but ‘good enough’

Mine slipped when pointing near the zenith whilst carrying a seven filter wheel and camera, but I'm sure it could have been improved with a bit of adjustment and perhaps a little fettling of the bearing surface on the draw tube.  I was intending to do just that but then a used Steeltrak came up so I replaced it instead.

James

[johninderby]

Think with the stock ED80 focuser being a simpler “less expensive” unit there does seem to be quite a bit of variability in how well they perform. 

Have a Baader Steeltrack refractor focuser on my 8” cassegrain and it does work extremely well. 👍🏻👍🏻👍🏻

[tooth_dr]

33 minutes ago, JamesF said:

Mine slipped when pointing near the zenith whilst carrying a seven filter wheel and camera, but I'm sure it could have been improved with a bit of adjustment and perhaps a little fettling of the bearing surface on the draw tube.  I was intending to do just that but then a used Steeltrak came up so I replaced it instead.

James

Apart from tightening the main Allen screw I didn’t do any other adjustment such as filing the drawtube flat etc.  I had a 7 x 2” EFW which is no light thing either along with a 8mp Kodak CCD. I fitted a SW motor to mine, and never needed to use locking screw on the focuser.

[ollypenrice]

2 hours ago, johninderby said:

The Baader is more durable than the Moonlite and having owned both would go for the Baader on an 80mm scope. 

So would I. The Moonlite strikes me as being more of an exercise in prettiness than function, though it's super smooth for Dob users where it will remain horizontal. Mine started slipping, which isn't surprising given that the roller drives shiny anodized aluminium. The Steeltrack has far more grip but the Diamant is the top choice from Baader. If using robotic focus you really don't want any slippage. Little competes with the FT R and P but the price is out of proportion with the cost of the scope in this case.

Olly

[Piero]

Baader is a very serious company in my opinion. I've never had issues with their products. 

The "diamond" model looks like a cracking piece of engineering.

[joe aguiar]

8 hours ago, tooth_dr said:

I’m going to say no here, I think there is little wrong with the stock ed80 crayford focuser.  It can handle a FR, EFW and CCD.  It’s on the limit but ‘good enough’

I dont think it's good enough when sw had their apo evostar sale in Oct I bought the sw 100f9 evostar.  I bumped the focuser on the first night and it didnt work again.

I sold the scope. I even did a utube video explaining what happen.

It's great it comes with a dual speed to begin with but they r not great quality. I would say ok quality for visual maybe but not for imaging. 

A focuser can be like an acromat scope some find the colour ok while others think the colour correction is not ok.

Maybe u got a very good one where I didnt.but most people who do ap have to upgrade to a better focuser. 

If you feel u dont and like it that's fine too of course I cant speak for 100%  for everyone either but from my findings this is what I think

Joejaguar 

Edited December 27, 2019 by joe aguiar

[Vox45]

14 hours ago, johninderby said:

Rotation is pretty well standard with all crayford focusers. The Baader also has 5 mounting posrions for accessories so more than one finder shoe can be used. 

thank you all for your answers. I've had my eye on the Baader Diamond Steeltrack for quite a while so there seems to be a consensus on this beeing the right choice for my 80ED

I was put off by the fact that there is no mounting shoe for my guide scope so I am a bit curious about what you said johninderby ? Do you mean that it is possible to install a shoe on the baader focuser ? No DIY hole drilling or anything like that needed ?

Thanks

[Vox45]

9 hours ago, JamesF said:

One of the particularly nice features of the Steeltrak if you're intending to motorise it is the built-in gear ring on the focuser spindle.

James

Yes James that is a very good point ! I did not notice that at first, thank you for pointing that out. One less part to worry about

[tooth_dr]

1 hour ago, joe aguiar said:

I dont think it's good enough when sw had their apo evostar sale in Oct I bought the sw 100f9 evostar.  I bumped the focuser on the first night and it didnt work again.

I sold the scope. I even did a utube video explaining what happen.

It's great it comes with a dual speed to begin with but they r not great quality. I would say ok quality for visual maybe but not for imaging. 

A focuser can be like an acromat scope some find the colour ok while others think the colour correction is not ok.

Maybe u got a very good one where I didnt.but most people who do ap have to upgrade to a better focuser. 

If you feel u dont and like it that's fine too of course I cant speak for 100%  for everyone either but from my findings this is what I think

Joejaguar 

I do have an issue with you suggesting that it is essential to upgrade your focuser to do AP.   It's just incorrect and misleading to newcomers.   I dont wish to derail the thread any further though, so I'll leave it that.

[johninderby]

Here you go. Couple of pics from the manual.

https://www.baader-planetarium.com/en/downloads/dl/file/id/175/product/2858/instruction_manual_for_all_baader_diamond_steeltrack_bds.pdf

[Adam J]

8 minutes ago, tooth_dr said:

I do have an issue with you suggesting that it is essential to upgrade your focuser to do AP.   It's just incorrect and misleading to newcomers.   I dont wish to derail the thread any further though, so I'll leave it that.

I have owned two myself and the issue for me was that while one of them was good the other was terrible. The design is not horrible in of itself its just quality control on a mass produced cheap as chips focuser is not great. .

[johninderby]

Yes it’s the luck of the draw with the stock focuser.

The tolerances of the parts used in one of these cheap focusers can stack up right and it can work very well or the tolerances can stack up the wrong way and it can be beyond any adjustment or fiddling with to make it work right.

Edited December 27, 2019 by johninderby

[Vox45]

12 minutes ago, johninderby said:

Here you go. Couple of pics from the manual.

https://www.baader-planetarium.com/en/downloads/dl/file/id/175/product/2858/instruction_manual_for_all_baader_diamond_steeltrack_bds.pdf

 

That was my last worry about making the jump to another focuser ! Now I see that I can get a much better focuser and not lose the shoe for my guide scope ...

I already own a Baader click lock as well as a baader Zoom and a Baader Canon T-Ring T- 2 / M48 (part : 10708) so far I've been impressed with the quality of the brand so I have no worries that this will be a good upgrade to my scope  

Thank you !

[tooth_dr]

The law of averages - I've had two and both were able to carry everything thrown at them.  Although if the posters ED80 cant hold a Canon 1000d, then there is something very wrong with it.

[Vox45]

1 minute ago, tooth_dr said:

The law of averages - I've had two and both were able to carry everything thrown at them.  Although if the posters ED80 cant hold a Canon 1000d, then there is something very wrong with it.

The focuser does not slip under the weight per se, it just does not always move the draw tube "in", in a reliable manner.

There is a fair amount of slippage when pointing to or near the Zenith and I am not always aware that the focuser is in fact not moving at all when I issue a move "in" order to the electric focuser (moving "out" is fine). I did follow the turorials out there to make it "better"  to no avail...

[tooth_dr]

1 minute ago, Vox45 said:

The focuser does not slip under the weight per se, it just does not always move the draw tube "in", in a reliable manner.

There is a fair amount of slippage when pointing to or near the Zenith and I am not always aware that the focuser is in fact not moving at all when I issue a move "in" order to the electric focuser (moving "out" is fine). I did follow the turorials out there to make it "better"  to no avail...

I know what you mean. If you intend to go fully automated then that isn’t going to work. FWIW I have a stepper motor / moonlite Crayford on another scope, and whilst it’s a bit early to say (only had it 3 months), it seems accurate and reliable, and a different league to the SW focuser.