Hadley Telescope M4 Heat Insert Remix

I wanted to print a Hadley, but I preferred to use heat inserts instead of nuts. So I completely redesigned the model from scratch. This model is made for M4 hardware and OD 12mm rods, using heat inserts with OD 6mm and 6mm length. The model is fully parametric, so if you wish to use different hardware just send me a message and I will adjust it for you. I will share the Fusion 360 files later, after some clean up. Check the remixes for a version made for OD 0.5" rods. 

Building the telescope was a joy! Everything fits together very well, there's no slop anywhere and it feels very firm. However so far I only printed this myself. I'd appreciate any feedback!

Note: this remix does not include a focuser. I suggest Hypatia - the Crayford style focuser I designed. However you can use any of the other Hadley compatible focusers.

Print instructions

Test print!

I recommend you print the test print first, use the modifier file!

• Make sure the rods fit nicely; snug is okay, but make sure you can still easily move them. If they require force, getting them on the LTA and UTA is going to be difficult. Keep in mind you may need to move them around to get the focus right.
• Try putting in the heat inserts. Make sure they're flush, and try to put a bolt through after you did. There may be some plastic pushed into the hole when you add the inserts, but this should come out fairly easily when you screw a bolt in.
• Try putting a bolt through the holes.

Colors

Print in whatever color you like. The model contains 2 sleeves, one for the UTA and one for the LTA. Print these in black for optimal contrast. Same goes for the spider, secondary mirror holder and the baffle. The UTA sleeve has tabs that go around the rods, it is held in place by the baffle underneath. I noticed that the tolerances in the black parts of my print were a bit tighter than the pink ones, so print a test piece for both to be sure.

Slicing instructions

I printed mine using a 0.6mm nozzle, with 3 perimeters, 40% cubic infill, 0.6mm linewidth for the external perimeters and 0.8mm for the rest. 

Modifiers

I have uploaded .3mf and .step files (in zip) for each of the components, and in some cases I added a file suffixed by _MODIFIER. It is important that the area around a heat insert is printed at 100% infill, these modifier files let you do that. I prefer using the .step files in PrusaSlicer 2.5 because it works very easily, the modifiers are exactly in the right spot. With .3mf they sometimes need to be repositioned. Note that sometimes the step files may give a warning that there are some open edges. This did not give me any issues, but you can click on the warning symbol and PS will fix the model for you.

This is how you add the modifier. Right click to get this menu.

Here's how you change the infill. Set it to 100%. Prusa slicer may give a warning about the infill type and change it to rectilinear for just this modifier. This is fine. After slicing, check to see that you got the intended result, below is an example.

Supports

The model does not require supports anywhere. For a few prints I added a brim to prevent the corners from lifting. Manually adding some circles in these areas suffices, a full brim is not necessary, as below.

Sleeves and baffle

The LTA sleeve will print beautifully in vase mode, but the UTA sleeve unfortunately can't be printed in vase mode because of the hole in the side. The thin walls are 0.8mm thick, which was 1 perimeter for me.  The Arachne perimeter generator caused some issues for me with the thin parts of the sleeves and the baffle. I recommend turning it to classic for these files.

For the other parts, Arachne gave the better result.

Assembly instructions

Most of the assembly is pretty straight forward, here's a few pointers. If anything is unclear, don't hesitate to reach out!

Heat set inserts

Make sure you use the right kind of heat insert! See this article by CNC Kitchen for more info.

For inserting them I used a temperature of 200° C, about the same as my printing temperature. Try to insert them as straight as possible, you'll be okay if they're a little off though. There are special tips for your soldering iron to fit in the inserts, I found these very helpful. I recommend you install all the inserts before starting assembly.

Upper Tube Assembly

The most difficult part is the spider, which has a lot of hardware. I found it easier to first glue the secondary mirror to the holder before installing it. Be careful when handling it.

Spider assembly

1. Add the heat inserts in the secondary mirror holder and the spider. The central part of the spider needs 3 inserts, the very middle one needs to be free!
2. Screw the thumb nut all the way onto the M4x50 screw. Stick the screw through the spider from the top down. The top is the side with the inserts. Make sure it can move up and down freely, without having to turn it.
   • Note: there is not a lot of space in between the adjustment nuts. A 12mm diameter thumb nut should fit. I couldn't find any of that size so I used a regular nut instead, which works fine.
3. Add the spring on the screw, and put a flat nut on top. Tighten the nut to compress the spring, to make room for screwing on the secondary mirror holder
4. Screw on the secondary mirror holder as far as it'll go. Use a wrench to tighten the nut up against the holder to lock it in place.
5. You can now use the thumb nut to adjust the distance of the secondary to the spider. When collimating the mirror, you use this to make sure the secondary is exactly in the middle of the focuser. About 16mm from the bottom of the spider to the top of the secondary holder is a good place to start.
6. Next, add the 3 adjustment screws, also M4x50. When collimating, they tilt the secondary to make sure it is aligned perfectly. Screw them through the inserts, and add the cap nuts.
7. For attaching the spider to the UTA, use M4x8 screws.

UTA Assembly

Slide the sleeve into the UTA. It should fit fairly secure just by friction alone, but adding the baffle underneath will make certain it stays in place. Add a focuser, attach it with M4x16 screws

Middle Tube Assembly

This one is pretty simple. The bearings do not need any inserts (the picture above is from an older version). I used M4x25 screws to attach them. You can use the center hole for attachments, e.g. if you want to use a spring to add some extra friction. 

(Note: the bearings need not be black, it just looks cool 😎)

Lower Tube Assembly

This assembly is similar to the UTA, a bit finicky too in its own way. 

1. Screw the thumb nuts all the way onto the adjustment screws (M4x50).
2. Stick the screws through the bottom of the LTA, once again make sure they can move up and down freely! 
3. Use the screws to guide the sleeve into the main body. The sleeve should fit nice and snug, once it is in there it is hard to turn it or get out again.
4. Add the springs on top of the screws, and the nuts on top of that. Tighten the nuts to make room for the mirror cell.
5. Set the mirror cell on top and screw the screws in as far as they'll go. Tighten the nuts up against the mirror cell to lock the screw in place.

Rods

Install the rods using M4x12 screws. I recommend doing this last.

Mirrors

Follow Maff's instructions in the original on how to install these, make certain you have the right glue. I highly recommend printing mirror covers (see the remixes), and using them as soon as you install the mirrors, to protect them. My secondary mirror fell off because I used the wrong glue. It crashed right into the primary, causing a big chip and some scratches and a dent in my ego. Don't do as I do.

I installed the primary after assembling the UTA, and the secondary before assembling the spider. Check the remixes for a primary mirror installation support.

Bill of Materials

I recommend you get some spares in case you lose any or miscalculation on my part. I bought M12 screws in bulk since that was cheaper.

Other notes

• There is a zip containing all files, including step files. F360 source file will be added later as it still needs some clean up.
• Check out Maff's wonderful discord server! There's a great community, perfect if you have any questions.
• I wish you clear skies!
   

Updates

• 14-12: added test files.