Considering the OVL focuser for 80ED

[ArgusFPV]

Hi all, as in the title I'm considering fitting my SW 80ED DS pro with the upgraded focuser. I'm having alot of slippage issues despite making multiple adjustments (FLO even sent me a handy guide). I'm kinda done with taking it apart and rebuilding the focuser now so I'm seriously considering getting the upgraded version. I use my rig for imaging so is there any special considerations I need to make i.e. how it will change my image train. I use the SW reducer/flattener with a Canon 600d. 

Thanks in advance

Lee

[carastro]

Watching this with interested as I have had a slippage problem recently with the same scope.  I have had it for a few years and only recently started to be troublesome.  Some-one kindly adjusted it for me as I wouldn't have a clue what to do.   But if it happens again I might be having to do the same.  

Sorry I can't offer any information of use to you.

Carole 

[Davey-T]

3 minutes ago, carastro said:

Watching this with interested as I have had a slippage problem recently with the same scope.  I have had it for a few years and only recently started to be troublesome.  Some-one kindly adjusted it for me as I wouldn't have a clue what to do.   But if it happens again I might be having to do the same.  

Sorry I can't offer any information of use to you.

Carol

Lots of good reviews on FLO

Dave

https://www.firstlightoptics.com/skywatcher-focusers/dual-speed-2-crayford-focuser-for-sky-watcher-refractors.html

[johninderby]

I’ve had a couple of the Skywatcher crayfords and found they are fine as long as you don’t put much load on them. Also they don’t last as long as say a Baader due to the cheaper materials used. However they fairly well priced.

[ArgusFPV]

7 minutes ago, Davey-T said:

Lots of good reviews on FLO

Dave

https://www.firstlightoptics.com/skywatcher-focusers/dual-speed-2-crayford-focuser-for-sky-watcher-refractors.html

Yes from what I can tell the OVL focuser is great value for money and a pretty good upgrade from the stock focuser, especially for a beginner on a budget such as myself. 

[JamesF]

I have to admit that I prefer the likes of the Revelation R&P focuser for imaging, but I was surprised to see that it's so much more expensive :(

https://www.telescopehouse.com/accessories/focusers/revelation-rack-n-pinion-focusers/revelation-superfocus-2-inch-rack-n-pinion-refractor-focuser.html

James

[johninderby]

Worth looking for a second hand Baader focuser as an alternative.

[JamesF]

2 hours ago, johninderby said:

Worth looking for a second hand Baader focuser as an alternative.

Definitely.  I'm in the same position (want to replace the focuser on my ED80) and a used Baader Steeltrak is probably my optimal solution.  I have one on my C9.25 and I'm very happy with it.

James

[tooth_dr]

2 hours ago, johninderby said:

I’ve had a couple of the Skywatcher crayfords and found they are fine as long as you don’t put much load on them. Also they don’t last as long as say a Baader due to the cheaper materials used. However they fairly well priced.

Genuine question John, but what does not last as long in the SW focusers compared with a baader?

I have a SW focuser motor on both of mine and this really makes the difference. It doesn’t slip now. 

[tooth_dr]

3 hours ago, ArgusFPV said:

Hi all, as in the title I'm considering fitting my SW 80ED DS pro with the upgraded focuser. I use my rig for imaging so is there any special considerations I need to make i.e. how it will change my image train. I use the SW reducer/flattener with a Canon 600d. 

Thanks in advance

Lee

Lee I don’t think that that is a particularly heavy load. I used a pair of ED80s regularly both with Canon 40d and 0.85x Reducer/Flattener, and there were no issues with slippage.  I’d say that’s a similar weight to yours.

I moved onto an Atik CCD and filter wheel and then got slippage. The addition of the SW motor focuser eliminated this entirely.

I’d look at adjusting the barrel contact profile first before splashing the cash personally. 

[ArgusFPV]

2 minutes ago, tooth_dr said:

Lee I don’t think that that is a particularly heavy load. I used a pair of ED80s regularly both with Canon 40d and 0.85x Reducer/Flattener, and there were no issues with slippage.  I’d say that’s a similar weight to yours.

I moved onto an Atik CCD and filter wheel and then got slippage. The addition of the SW motor focuser eliminated this entirely.

I’d look at adjusting the barrel contact profile first before splashing the cash personally. 

I've adjusted mine multiple times now using a guide FLO sent me. Made sure the contact is perfectly level and the pressure is appropriate. It works for a little while but always ends up slipping again. 

[johninderby]

9 minutes ago, tooth_dr said:

Genuine question John, but what does not last as long in the SW focusers compared with a baader?

I have a SW focuser motor on both of mine and this really makes the difference. It doesn’t slip now. 

The Baader Diamond Steeltrack is just a higher quality focuser using better materials and made with higher precision so it will last longer without wearing. Basically it’s you get what you pay for. 

“How does it work? Imagine a surface like a fine emery cloth, if you push two of the surfaces together their grits mesh. On a microscopic level thousands of 'teeth' grip each other, like teeth on a rack and pinion. The SteelTrack has a very fine grit made from industrial diamonds applied to what would normally be (on a Crayford focuser) a smooth metal roller bearing, which meshes with a textured metal surface on the focuser drawtube. The result is remarkable, it provides the smooth action of a Crayford with no backlash and a higher load bearing capacity. We hope that makes sense, it is much easier to understand when the focuser is in front of you.”

[tooth_dr]

2 hours ago, ArgusFPV said:

I've adjusted mine multiple times now using a guide FLO sent me. Made sure the contact is perfectly level and the pressure is appropriate. It works for a little while but always ends up slipping again. 

Can you post that guide here? Might be useful for others too. 

[tooth_dr]

2 hours ago, johninderby said:

The Baader Diamond Steeltrack is just a higher quality focuser using better materials and made with higher precision so it will last longer without wearing. Basically it’s you get what you pay for.

I didn’t realise where the name came from! That makes a lot of sense now!

Better by the sounds of it. But still not sure what part wears out on the SW focuser?

[John]

The OVL focuser uses a smooth steel rod bearing against an anodised, shiny flat section to propel the focuser drawtube back and forth. This arrangement has limits in it's weight carrying capacity and needs (in my experience) very careful adjustment to work well. The Baader approach uses slightly roughened surfaces on the flat section and the steel rod which provides more, and easier to adjust, control and weight bearing capacity.

 

[JamesF]

I've just been having a browse around for R&P focusers.  I can't really find anything between quite cheap and nasty models that I wouldn't give house room and £250-ish versions.  Yet there are Crayfords by the (light) bucketful that sit nicely between the two in terms of price.

Have R&P focusers just fallen out of fashion as non-bank-breaking upgrades these days?

James

[ArgusFPV]

10 hours ago, tooth_dr said:

Can you post that guide here? Might be useful for others too. 

https://teleskop-austria.at/information/pdf/SWN1507eq3_Skywatcher_Crayfor-Auszug_justieren.pdf

Yes, it's a pretty good guide! I hope it helps some folk out. 

[tooth_dr]

2 hours ago, ArgusFPV said:

https://teleskop-austria.at/information/pdf/SWN1507eq3_Skywatcher_Crayfor-Auszug_justieren.pdf

Yes, it's a pretty good guide! I hope it helps some folk out. 

Have you physically smoothed out the flat surface on the drawtube?

Edited August 10, 2019 by tooth_dr
Detail

[tooth_dr]

 

 

[ArgusFPV]

On 10/08/2019 at 12:07, tooth_dr said:

Have you physically smoothed out the flat surface on the drawtube?

I'm not sure what you mean by that. Do you mean have I used an abrasive on it? 

[tooth_dr]

51 minutes ago, ArgusFPV said:

I'm not sure what you mean by that. Do you mean have I used an abrasive on it? 

The video above shows that the contact point on the draw tube with the focusing wheel/bar can be an issue. I took a screenshot of the part of the video showing the issue with the drawtube - the shiny / dark edges are the only places the bar is contacting. So no adjustment of the screws will work until this is sorted.   Perhaps this is what needs done with yours to improve surface area and contact and prevent slipping. 

Here are mine - before with just the DSLR and CCF I didn’t have any issues.  I went down the route of two CCDs and the addition of the EFW put too much weight so I added motorfocusers to assist in focusing and also to prevent slipping - I cant use the focus locking screw as access is limited to it. £25 (second hand) for the motor, no more issues.

I’m just trying to save you money 😂

 

[ArgusFPV]

2 hours ago, tooth_dr said:

The video above shows that the contact point on the draw tube with the focusing wheel/bar can be an issue. I took a screenshot of the part of the video showing the issue with the drawtube - the shiny / dark edges are the only places the bar is contacting. So no adjustment of the screws will work until this is sorted.   Perhaps this is what needs done with yours to improve surface area and contact and prevent slipping. 

Here are mine - before with just the DSLR and CCF I didn’t have any issues.  I went down the route of two CCDs and the addition of the EFW put too much weight so I added motorfocusers to assist in focusing and also to prevent slipping - I cant use the focus locking screw as access is limited to it. £25 (second hand) for the motor, no more issues.

I’m just trying to save you money 😂

 

Ah!  I see what you mean now! I haven't done that yet. I'd spotted that video previously on my travels but skimmed over it as it was a different focuser but I totally see how it's completely relevant now. I'm pretty sure I have a sharpening stone like that kicking around too. I'd be a bit nervous of not getting it completely flat but at this point any improvement in the contact patch would be welcome. I'll pull it out and see what it looks like at the next opportunity I have and report back. Thanks mate  

[ArgusFPV]

Got round to taking a look at mine today. As you can see it's pretty clearly been running on just the outside edges. Got an old wet polishing stone and ran up and down the length of it for a while with nice even strokes until the finish seemed uniform being careful to make sure the stone remains flat the whole time. Kept going until I was happy with the finish, cleaned it up and put it all back together and adjusted it. I must say, I'm pretty impressed, the level of grip the rod has on the draw tube now is massively improved. Everything feels much more positively engaged while remaining firm but smooth. I haven't used it in anger yet but just testing it by running it in and out and some light pulling on the draw tube seems very promising! Thanks ever so much for your help. One less worry now! 

[johninderby]

Nice job. 👍🏻

A low cost focuser can be greatly improved with a bit of attention to detail.