Bresser Dual Speed Gear Set - Slipping Fixed!

[cloudsweeper]

Others must have come across this problem.  After a few turns, the knob starts to slip, making it of little use.  The little 3mm grubscrews (left side on photo) often don't fit securely against the focuser shaft, and soon work loose.

The shaft has a hole going through where the grubs contact it, so I thought different grubs would be the answer, and went for M3 x 6mm cone point (instead of flat-ended) grubs.  (boltbase on Ebay are good suppliers.)

To be certain the grubs actually went into the hole, I stripped the whole thing down down, and even did a bit of filing.  This might not be necessary however.

Now the gear set works a treat and the 1:10 reduction makes focusing more precise (especially in a fast 'scope).

Very pleasing, and for very little expense!

Doug.

[Neil H]

Doug so over all your pleased with this it is going to be my next job on my 127 bresser

Edited September 24, 2020 by Neil H

[cloudsweeper]

2 hours ago, Neil H said:

Doug so over all your pleased with this it is going to be my next job on my 127 bresser

Yes Neil - very pleased.  The above procedure was used on my Bresser 102S frac.  I also put one on the Bresser 10" Dob, but that seemed to work without making any alterations.  (But I'll know what to do if it plays up!)  I didn't get one for the Bresser 127L - figure it's a bit less vital for a slower 'scope, so saved the money - but of course it would be a good addition! 

Doug.

 

[Barry-W-Fenner]

On 24/09/2020 at 10:30, cloudsweeper said:

Others must have come across this problem.  After a few turns, the knob starts to slip, making it of little use.  The little 3mm grubscrews (left side on photo) often don't fit securely against the focuser shaft, and soon work loose.

The shaft has a hole going through where the grubs contact it, so I thought different grubs would be the answer, and went for M3 x 6mm cone point (instead of flat-ended) grubs.  (boltbase on Ebay are good suppliers.)

To be certain the grubs actually went into the hole, I stripped the whole thing down down, and even did a bit of filing.  This might not be necessary however.

Now the gear set works a treat and the 1:10 reduction makes focusing more precise (especially in a fast 'scope).

Very pleasing, and for very little expense!

Doug.

Hi Doug.

Thanks for this info.  I am having this exact same problem with my 102S. I have tightened the stock grub screw once which solved the issue but it instantly worked loose and had started slipping again. I was trying to view through the scope at 4am this morning and the fine focus side is unusable. I had to use the left side course nob for everything.

I'm going to order theses grub screws now. How tight did you do them up?

Thanks for your thread regarding this problem 👍

[cloudsweeper]

4 hours ago, Barry-W-Fenner said:

Hi Doug.

Thanks for this info.  I am having this exact same problem with my 102S. I have tightened the stock grub screw once which solved the issue but it instantly worked loose and had started slipping again. I was trying to view through the scope at 4am this morning and the fine focus side is unusable. I had to use the left side course nob for everything.

I'm going to order theses grub screws now. How tight did you do them up?

Thanks for your thread regarding this problem 👍

Barry - the hex profile is easily damaged, so I just use gentle finger pressure on the Allen key, plus a very little leverage on the short part at right angles.

Further to all this, the Bresser Dob (without a reducer) began to slip last night.  On inspection, the focuser shaft has the usual holes each side, bit is a bit flattened on one side only.  So I lined the regular grubscrew up to the flattened side, and it seems OK now.

It's just a matter of inspecting what's there and getting the best combination.  But Yes, the cone-ended grubs did improve things.

Hope you get the issue sorted!

Doug.