Milk bottle washer mod ?

[ThunderChild (Chris)]

Enjoying my new dob (although it's been cloudy lately - and just ask Steve about the lightning on Lake Mountain! ).
Just bought a metal case for $18 and some foam to make a really nice case for the EP's and things.

BUT

One thing with my dob mount - it is quite sticky, so I thought I'd perform the milk bottle washer mod. Sounds simply enough, but I just want to know the best way for cutting out circles without making jagged edges?
I assume it's important to get a nice, round, smooth edge - and I imagine that if I were to just use a stanley knife it would not be.

To make the center hole, I'm planning on squashing it between two pieces of wood and drilling.

Is there an known "better" way of getting these nice?

[barees63]

fwiw, my dob had a bumpy "sticky" feel to it, when I took the base apart I found one of the bolts (holding the vertical parts of the mount) had worked loose and was catching.. tightning those up fixed it and now it is quite smooth without milk-bottle washers.

[wavelandscott (Scott)]

I just used scissors to cut mine in approximate circle shapes...

I did not get too fussed about having them exactly shaped because I do not beleive that it is critical...the idea is to more evenly distribute weight so I recokon any shape would work.

Although I have not used them, I have heard that people have used old cd's to accomplish this as well...

I just used plain old 2 liter plastic milk jugs (lite milk actually) rinsed and dried and cut with a handy pair of scissors...don't tell my wife I used her "good pair"...

In any case, they work great...

[anthony2302749]

Here is a far easier thing to do, dismantle the base an give the bottom board (the base) a good spray of “Armorall” or “Mr Sheen” and rub it in well with a cloth, repeat a couple of times. Assemble the base, ensuring that you do not over tighten the centre bolt. The scope will now move a lot smother and with out the milk-bottle washer mod.

[ving (David)]

stanley knife... works fine

[Orion]

I know it's a bit more work but I think this way is better.http://www.iceinspace.com.au/forum/s...ead.php?t=5882

[astronut (John)]

Thunderchild, As others have said check that everything is ok with the mount.
If there are no problems try this, its called Super Lube it is a synthetic grease made in the U.S.A. Don Whiteman from Bintel recommended this and it works very well. Temp range -43C to +232C. It won't collect dirt and so keep mechanisms working effeciently. It's good for anything that moves. Cheers, John

[janoskiss (Steve H)]

Careful with that armourall. I know Roger from Bintel recommends it too. But one Dob that had that done was Wombat's at Snake Valley. Apparently the armourall worked allright at first but then went sticky pretty quickly. The base on that Dob had the worst sticktion I've ever seen. Maybe temperature extremes do funny things to that stuff. I'm too scared to touch it after having seen Wombat's scope.

Stanley knife will work okay for the milk jug washers. Use a bench drill with a sharp bit through the plastic sandwiched between two blocks of scrap wood for nice and clean edges.

[cristian abarca]

Hi Thunderchild. I have a home made dob mount and because my ota is rather heavy my mount didn't move as easily with it on. It moved really well on it's own though. I cut out the circles put them on and now my mount is much smoother. It doesn't jerk anywhere near as much. I cut the circles out with scissors. I measure the centre bolt and cut the centre hole a bit bigger so that it would not obstruct. With the centre cut out I drew a small circle with a texta and pierced it with the scissors, very carefully then I proceeded to cut them out. They are a little bit rough around the edges but it worked for me. You have nothing to lose by trying as it's such a cheap option. But do be careful when piercing the central hole as the scissors can cut through it very easily and in the process cut yourself.

Regards cristian

[anthony2302749]

Originally Posted by janoskiss

Careful with that armourall. I know Roger from Bintel recommends it too. But one Dob that had that done was Wombat's at Snake Valley. Apparently the armourall worked allright at first but then went sticky pretty quickly. The base on that Dob had the worst sticktion I've ever seen. Maybe temperature extremes do funny things to that stuff. I'm too scared to touch it after having seen Wombat's scope.

I would suspect that the “Armourall” had not been applies correctly in this case. The Armourall needs to be polished on to the base board same way you would polished it on to the dash of your car. Any excess Armourall would need to be wiped off before assembling the base. If excess Armourall was left on the base it could in all likelihood become sticky, but this is questionable, as your know your dash does not become sticky after applying Armourall.

When reassembling the base care must be take not to over tighten the centre bolt as it controls the tension between the base and Teflon pads. To loose the scope will move quickly at the slights touch, to tight the scope will be difficult to move.

[RAJAH235]

FWIW. Please run all surfaces dry. Any lubricant is un-necessary if properly modded & adjusted with teflon or milk bottle washers. Just speaking from experience. L.
ps. Only stuff I use is Kitten car polish on the tube & base to waterproof.
pps. Mr Sheen is rubbish. imho.

[ThunderChild (Chris)]

Thanks to all who responded - much appreciated.

Performed the milk bottle mod last night and the stickyness has improved.
As Janoskiss suggested, drilling the center holes worked Ok (and was faster than cutting them individually!)
Used four washers in the end. Five provided a magnificant, smooth turn but must have been a little too much because it had a slight wobble - so went back to four.

The altitude motion isn't as I'd like - so I might now look into using weights instead of springs.