Help installing Orion 2" Crayford Style Focuser on 12.5" Dob

[DutchmanV]

I own a 12.5" Orion Premium Deep Space Explorer and am not a fan of the 2" helical focuser it already has. I purchased an Orion 2" Crayford style focuser and was wondering if anyone had some ideas to maximize potential for the install and/or things to be aware of before i start. Thank You in advance for any help.

Brian

[NGC 1502]

Hi Brian, welcome to SGL, from the UK.

First thing to work out, is that the eyepiece will be close to the original distance from the tube, as it is with the old focuser, or at least within the focusing movement of the new one. Is the old helical focuser low profile ? If it is, the new focuser may place the eyepiece further out.

Easy to get near enough measurement if you focus up at infinity, and carefully put a ruler on the tube next to the focuser. Then transfer the eyepiece to the new focuser and see if that distance is within the focusing range, measure from the base of the new focuser where it will touch the tube. Quicker to do that than explain it. If your eyepieces are not parfocal, make sure they all come to focus within the focusing movement.

The rest is a matter of the bolt hole positions to attach the focuser, and the size of the main hole in the tube. Some filing or drilling may be needed, but it's all basic DIY, just take your time and don't rush. If you remove both mirrors, that will ensure no metal filings or debris get on them. Carefully clean the tube after drilling / filing.

All the best for the project, Ed.