Fitting Hex focuser 1:10 woes

[johninderby]

Congratulations 🥳

You have now mastered the black art of focuser knob upgrading. 😁

[HollyHound]

1 minute ago, johninderby said:

Congratulations 🥳

You have now mastered the black art of focuser knob upgrading. 😁

Instructions looked simple... reality was a bit more fiddly, but at least I know now and am able to adjust it whenever I need to 😃

[Matt01]

13 minutes ago, HollyHound said:

Instructions looked simple... reality was a bit more fiddly, but at least I know now and am able to adjust it whenever I need to 😃

Do you reckon it's worth it?

I have pondered it for a while now...

[HollyHound]

4 minutes ago, Matt01 said:

Do you reckon it's worth it?

I have pondered it for a while now...

I haven’t tested it in anger yet for observing (been cloudy here for a week), but I’m used to fine focus on my StellaMira, so thought why not.

The normal focuser however is perfectly smooth in operation, so certainly wouldn’t say it’s essential, especially given the upgrade cost.

@johninderby is the king of focuser upgrades, so he might have his own view on this 🤔

Edited November 13, 2020 by HollyHound

[cloudsweeper]

I'm a bit late on this particular thread, but the subject of the Bresser Reduction Gear has cropped up a few times recently.

I bought two, and neither worked as per instructions because they immediately slipped.

I took one of the focusers to bits to find out why, and saw holes in the focuser shaft.  The grubscrews supplied with the knobs are flat-ended and do not engage with those holes.  I bought some cone-ended grubscrews (M3 x 6mm) and fitted them carefully, and now the focus knobs work as they should.

It's rather poor to supply these items with screws that result in slipping and ineffective action.

Anyway, for a few pence I now have fine, smooth action on the Dob and short focus frac.  The long focus 127 can do without the modification since is has a higher focal ratio, and thus greater depth of focus.

Doug.

[johninderby]

No need to change the grub screws if you fit the extra grub screw on the upper part. Often not fitted as the supplied instructions aren’t very clear.

Edited November 13, 2020 by johninderby

[cloudsweeper]

A cone-ender both sides gives a positive grip and ensures a nice action.  Well worth it for a few pence.  😉

Doug.

[johninderby]

Did you fit this extra grub screw? I’ve fitted two of the upgrade knobs and both work perfectly withoit changing grub screws. 

Edited November 13, 2020 by johninderby

[cloudsweeper]

Yes, John.  I found that on fitting the units to both 'scopes, the knobs slipped (one in relation to the other) after just a few turns.  That's when I stripped one of the focusers down and noticed the shaft has a hole each side, and that one side is flattened.  I tried various ways of aligning the shaft with the grubscrews (including getting one to press against the flattened part), but still they slipped.  It simply wouldn't work for me, which is why I had the idea of the cone-ended grubscrews.  They engage with the holes and now the action is positive, smooth, and slip-free.  In some cases this might not be necessary of course, but should anyone have the same problem I had, I would recommend changing the screws.  Boltbase on Ebay are good suppliers:

https://www.ebay.co.uk/itm/M3-3mm-A2-STAINLESS-STEEL-CONE-POINT-GRUB-SCREWS-HEX-SOCKET-SET-SCREW-DIN914/231308431719?hash=item35db0e9167:g:06QAAOSwd4tT7d0I 

Doug.

[HollyHound]

26 minutes ago, cloudsweeper said:

In some cases this might not be necessary of course, but should anyone have the same problem I had, I would recommend changing the screws.

Thanks for the tip... mine seems ok, but if I run into issues, then I will certainly try this suggestion 👍