Heritage 130P - stiff struts when cold

[DevonSkies]

Hello,

I recently bought a Skywatcher Heritage 130P Flextube mini-dob.

I find when the scope is cold, the sliding struts become very stiff, so that collapsing the tube down after a session is very hard. In fact, it's so hard I'm afraid of breaking something! It feels like one strut is stiffer than the other. I have tried silicone lubricant,  but it didn't help. When the scope is warm, it slides up and down fine.

I was wondering if any other Heritage owners might have experience of this and have some tips to help? I notice there is a grub screw in the plastic assembly where the strut slides up and down. Is this anything to do with adjusting the tension? 

Thanks, 

Ed

[happy-kat]

The grub screw, one on each strut, is to be tightened when you extend the scope. I tend to leave mine loose all the time as it hold well when extended I only lock the struts if the trusses are partially lowered and I an using a webcam.

Mine is tight to close but slides easily once past the holding position.

[DevonSkies]

27 minutes ago, happy-kat said:

The grub screw, one on each strut, is to be tightened when you extend the scope. I tend to leave mine loose all the time as it hold well when extended I only lock the struts if the trusses are partially lowered and I an using a webcam.

Mine is tight to close but slides easily once past the holding position.

Do you mean the plastic thumb screw? I know these need to be loosened to slide the tube up and down. But there is also a small headless grubscrew on the opposite side of the assembly. That's the one I was wondering about. A Google search throws up a few threads from people who've had similar problems with struts seizing up.

I've also emailed the retailer, and will see what they suggest.

Thanks.

[happy-kat]

Never noticed another grub screw, mine has always slid with what I feel is acceptable grip.

Yes I have read of one other that gripped too hard and would not slide I think they got a replacement unit swap.

[brantuk]

The "headless grubscrew on the opposite side of the assembly" on each strut, holds a spring in place that squeezes a ball bearing onto the strut helping freedom of movement sliding it up and down. The ball bearing clicks into place when at the correct extension. All I can say is - when I undid mine I ended up chasing a ball bearing round the floor then fiddling frantically for half an hour to get the whole assembly (bb, spring, screw) back into place lol.

I used to keep my struts lightly lubricated with a thin wipe of furniture polish so they wouldn't seize up in the cold when the metal expands against the strut housings - seemed to work reasonably well. My scope was the 12" SW dob, not sure if it's identical on the 130 but wouldn'tbe surprised. Hth

[happy-kat]

That's useful to know

[DevonSkies]

I decided to have a go at adjusting the grub screws with an allen key. They do indeed seem to directly regulate the friction on the struts. It felt as if one strut was too tight and the other too loose, so I have adjusted both screws so that the friction feels about the same on both sides and the scope slides up and down easily.

I won't know until I take it outside and let it cool fully whether further adjustment is needed. I'll try it again next time the sky is clear.