Focuser tube play

[Treewick]

Hi,

I posted this in the "what tool for collimation" thread but I think it was unseen on the second page. My XT6 Orion Dob has some slight play in the focuser tube (rack and pinion) that does not effect its use for viewing but renders collimation with a laser difficult if not impossible because the piece wobbles in the tube. The wobble is negligible, but enough to cause issues with collimation. I have been using the provided collimation cap to make adjustments. Will the same play effect the use of a Chesire collimation piece? Also, has anyone else experienced this with their Orion scope - can it be corrected? If so how?

[brantuk]

Hmmm... there's usually a small screw in the underside of the focuser tube to tighten up any play and get it just right for movement in/out but not up down or side to side. Often its a tiny allen key bolt within a recess. Does yours have anything like that?

[Treewick]

I will have to scrutinize the focus tube assembly to try and identify such an adjustment slot. The best way I can describe the issue is a side to side wiggle. It does not affect the up or down motion and it’s very miniscule. It does not cause issues with viewing but it does make collimation with the laser impossible because collimator does not sit center in the focuser tuber and tends to rest to one side due to the angle of the tube and the slight amount of play. While in the focuser the collimator can be slightly tilted towards center and past with a slight touch of the finger. Although the wiggle is negligible I can swing the dot from one side of the collimation target clear across to the other

[brantuk]

Yes - I see what you mean. The best I can suggest is a self centering adaptor (SCA) for the collimator if you cant eliminate the wobble. I use the Hotech - they're expensive but a sound investment if you're a serious observer/imager. The adaptor expands in all directions inside the focuser tube so you get a perfect solid fit. Well worth it for the XT6 imho

(someone may have a better/cheaper alternative suggestion)

[Treewick]

Excellent! Thank you very much for your help.