SV181 SVBONY replacement focuser riser mod for D150F750 newtonian reflector telescope

This is a focus riser for a generic D150R750 6in Newtonian telescope OTA. (6inch / 150mm diameter, 750mm focal length)
This enables you to reach focus after you replace the plastic focuser on your telescope with the SVBONY SV81 all metal rack and pinion focuser. This is a low cost focuser but is much better than the plastic focuser that comes with most of these lower cost budget scopes. It will increase the focus max from 55mm to 90mm and therefore match the original focuser as shown in the images. You can always just add an extension in the focus tube with an adaptor, but this creates a more permanent solution and wont mess with your collimation by inserting tubes on the focal train
For the plate that goes inside the scope tube I iowered the curvature slightly to make it so there is a nice tight fit when bolted to the riser through the tube, Also it will limit light leak, Limiting light leak and covering existing focuser mount holes were the predominant reasons for the inside plate. However you dont HAVE to print the inner plate if you do so wish, you can bolt the riser the tube .

I didnt add bolt holes as the SVBONY focuser uses 4 bolts wheras my original, and most of the original plastic focusers have 3. you can align it yourself and then drill / bolt where you wish. It also gives you a little more freedom where to align the focuser with the secondary mirror to make it central to the focus tube, also making collimation easier.

Please note also, if you are new to telescopes and just want to upgrade the focuser, you will have to collimate your telescope when you install it. I use both a cheshire and laser colimator. For this type of scope thats really made for looking through as opposed to imaging (though you can do basic imaging) You can find low cost laser and cheshire collimators on ebay / amazon etc. Along with helpful guides on youtube etc.

I have included 4 stl files, 2 of which are the risers and 2 inside the tube' plates which the riser bolts to. The reason for this is some secondary mirror vane assembly have differences in depth ie how much of the outer frame actually fits over the telescope tube. The shorter version of the riser compensates for this and can be installed without hitting the vane assembly outer ring. Look at your telescope tube and choose the models you need.

Im currently working on a DIY 6in ota project, stripping a budget 6in reflector, and installing better parts. I will update telescope images using this riser at a later time.

You can use a multiple of different filaments. I chose ABS CF , (ABS carbon fiber) But ABS, PETG, ASA etc should be fine.though I would avoid filaments with a lot of flex or elasticity) .I use 80% infill but thats up to you. The higher end engineering filaments which include glass fiber or carbon fiber will yield you great results, I find ABS CF to be excellent, but PETG CF is also a filament I like to use for strength and durability, thus should be an excellent choice.

The original focusers , well at least mine, have a hollow plastic base, but this way you can create an almost unbreakable solid base from much better materials with solid infill if you wish.
If you live in a somewhat humid climate, I would avoid standard PLA.

Some people may think replacing a plastic focuser with an all metal one, but adding a plastic base to increase max focus defeats the object, yet you can print with a plethora of filaments, including engineering grades, and can go with a 100% extremely stable solid infill, and (almost) flex free solution (nothing is 100% after all). Also, the quality-of-life improvements, such as much smoother motion, make a massive difference. There is also the possibility you have to replace your original focuser because its damaged or broken.

Printed with QIDI XMAX 3 printer

the SVBONY focuser model and amazon link is in a readme file

be creative, and have fun