Cant Collimate 10" Dob.

[wookie1965]

It's not the size - if you look at my washer it has depressions for each of the three screws (that helps to locate and prevents washer from sliding out)

Yes i saw that and was wondering about it as with the screws leaving depressions i couldn't get collimation because it kept slipping back in the same holes that is why i flattened it in the astro shed video he uses a flat washer so the screws push against that not the mirror stalk. My washer was too big in circumference that's all and the hole in middle was too big so when moving one screw was slipping pushing it to side then the same when doing another screw.

[Moonshane]

I think your washer was also a little bit too thick Paul and was taking up all the slack on the central bolt. this meant that the secondary holder was tight against the spider hub allowing no or very little tilt. Jason's recommendation of no metal washer and only plastic (milk bottle) washers works better than anything I know. if you have found your own way though that's great too

[wookie1965]

I think your washer was also a little bit too thick Paul and was taking up all the slack on the central bolt. this meant that the secondary holder was tight against the spider hub allowing no or very little tilt. Jason's recommendation of no metal washer and only plastic (milk bottle) washers works better than anything I know. if you have found your own way though that's great too

Yes i think your right i have used two plastic washers (milk bottle) and it is now brilliant if in the future i have to do anything i might consider a 1mm washer but not for now had scope out the other night Jupiter was better than i have ever seen it in 15mm BST Ring nebula was superb and Orion i could make out 6 stars only ever been able to see 4 i am well happy.

[bambuko]

Yes, I think I will make mine thinner than the original 2.5mm to permit more adjustment...

[Jason D]

One main advantage of using washers made from milk plastic bottle is the inherent elasticity missing in a metal washer. The tiny elasticity works like tiny springs. When it is time to make that last tiny adjustment, you can tighten/untighten one set screw without the need to touch the other two.

Jason

[bambuko]

It works for you, and that's fine

I can also understand the appeal of this solution for people without well equipped workshop.

Inherent plasticity/creep (not elasiticity) in plastic washer solution can work for and against you.

It least I know that my metal washer solution once adjusted will remain so.

I can also adjust one of three screws without touching the other two - that's the hole point of having three screws and sliding washer.

[bambuko]

It's a bummer not being able to edit (roll on 250 posts)

hole was meant to be whole (sorry)

[Jason D]

It works for you, and that's fine

I can also understand the appeal of this solution for people without well equipped workshop.

Inherent plasticity/creep (not elasiticity) in plastic washer solution can work for and against you.

It least I know that my metal washer solution once adjusted will remain so.

I can also adjust one of three screws without touching the other two - that's the hole point of having three screws and sliding washer.

When you use plastic washers made from milk bottles, you can "over-tighten" one set screw for that last fine adjustment without the need to touch the other two. The amount of elasticity is controlled by the number of stacked washers (one to three stacked). How can you "over-tighten" one set screw by a tiny amount without loosening the other two with a metal washer? Metal washers are rigid.

If you get a chance try the plastic washers and compare. As you mentioned, masking plastic washers does not need a well equipped workshop -- just a pair of scissors. You can even cut them diagonally and slide themwithout the need to remove your secondary mirror as shown in the attachment.

Jason

[hippie]

I used my scope for the first time last night since fitting that washer,  With a short break in the clouds and homed in on Andromeda with great results, I Didn't need to do any other adjustments as the star test seemed spot on Yeahhhh!,   I Had the best  views of Andromeda from my lounge window to date so far now hooooray!,

Waiting for clear sky's now to get out into the forest were we have darker sky's to try the scope out fully on Jupiter the Pleiades & Orion clusters, Hopefully soon  .

I will keep in mind the plastic washers in case I get any slip with the steel washer I fitted, Thanks Guys.  

[bambuko]

There is more ways than one to skin whatever animal you are dealing with and I didn't set out to convince or change you.

If the method you are using works for you and you are convinced that it offers you some advantage, that's absolutely fine with me .

[Jason D]

I believe you have misunderstood. I am not trying to convince you with anything. I suggested you try the plastic washers then decide for yourself. I also asked for clarification about your statement "I can also adjust one of three screws without touching the other two". I am not sure how you can do that with a rigid metallic washer.

But that is OK. I do not believe this exchange is going anywhere. Enough said.

Jason