Shimming a focuser

[[1ponders] (Paul)]

I've been trying to find some really thin material to shim the slop out of a R&P focuser. The sort of stuff I'm looking for is the material that is used to pack out the dew shield of refractors so the shield doesn't fall off. If you have an Orion 80ED or a Synta or Celestron refractor, check out the inside if the dew shield. That's the stuff I mean. It's kinda like a very thin felt that's sticky on one side.

Or if anyone can think of a substitute let me know.

Or any other ideas for limiting the movement in the barrel of the focuser. There are no adjustment screws to do this.

[RAJAH235]

Hi Paul, Try 'Dotmar' in Talavera Rd., North Ryde. Not sure if they will supply to the public tho. Mate of mine works at a Co. that uses heaps of diff. thickness's of TEFLON tapes/blocks/sheets etc etc........
Got some really thin stuff, (5/10/20? thou, sticky 1 side), off him to re-shim my r&p couple of years ago. Now I have zero slop + no image shift. Electric focuser is really smooooooth. np.
HTH. L.
Googled > http://www.dotmar.com.au/
> http://www.ferret.com.au/Companies/Dotmar-EPP
> http://www.ferret.com.au/articles/21/0c02bf21.asp

[[1ponders] (Paul)]

Thanks Laurie. You don't happen to know the brand or name of the "really thin stuff" do you? Probably wants to be between 10 and 10 thou.

[ballaratdragons (Ken)]

Originally Posted by ponderosa

Probably wants to be between 10 and 10 thou

.Paul, I think Laurie might have a bit of trouble understanding the size you are after. Between 10 and 10?

[[1ponders] (Paul)]

I thought it was pretty specific actually Ken

Sorry Laurie, I meant between 10 and 20

[beren]

Paul you might find something in Lincraft, i get dragged into going there everytime the missus drags me shopping , lots of crafty items [and other chick stuff] but i remember seeing felt and logging that down for future reference

[ving (David)]

ok ready for a good laugh

woud a coke can be thin enough? its amazing the uses of coke cans

[[1ponders] (Paul)]

Not such a silly idea ving. I'll keep it in mind.

[janoskiss (Steve H)]

I was at Bintel on Friday and Roger (Davis) was telling me and Daniel(sun) about how to do just this. Unfortunately I wasn't paying attention properly . All my brain could do is go "get the crayford, get the crayford, get the crayford...". My R&P is pretty shocking since I hung a couple of kilos worth of camera gear off it.

[RAJAH235]

Paul. it's all 'TEFLON'. Just diff varieties.... eg; block/tape etc... Do what I did & double the tape strips up where nec. or get a few diff. thickness'sssss.
Aluminium = very hard to glue.
I haven't found a good aluminium glue yet!
Lots of better stuff avail.
Paul, you might also try 'Cadillac Plastics'. They might just have some teflon as well.
HTH. L.

[[1ponders] (Paul)]

Right, I'm on a mission. I was thinking about doubling up the the tape Laurie. Now the biggest question is, do I apply the tape to the inside of the focuser barrel or to the outside of the sleeve that moves in and out?

[RAJAH235]

Paul, when you remove the focuser sleeve, you'll see the original tape/felt is in/on the inside of the focuser,(fixed bit), not the sleeve. Just take the old 1's out & start with 3 'thick' tapes. Space @ 120 degrees & cut them ~10/15 mm wide. If you find it nec. to double up, use thicker ones as base. One should be placed at the top of the tube opposite the rack groove. Helps with longitudinal forces.
I think from memory, I used about 3 or 4 layers of varying 'gauges' in mine to get it 'just right'!
Just make sure there's no dirt/dust/grease etc inside. Oh, & buy some thin double sided adhesive tape too. Might come in handy.
HTH. L.