SP-8 AliExpress BTU compatibility

[efogdev]

SP-8

For example, this ones.

Knowledge base

Compatibility: ❗️not compatible, separate model(s) available
Differences: same height, different (greater) diameters.
Comments: the steel ball version feels close to Rexroth, but not quite. It's a solid option, but less smooth and more loud.

Links

50-55 mm shell here: https://github.com/adept-anyball/mod/tree/master/50-55mm%20ball

Showcase

Rexroth for comparison: https://github.com/user-attachments/assets/d8cfdc46-2cf6-4129-a199-c57a8b72ef77
SP-8 steel ball: https://github.com/user-attachments/assets/b1ad3f8a-16da-45e3-a90e-de85919935fa
SP-8 nylon ball: https://github.com/user-attachments/assets/21eb35c5-aafb-43b8-8942-3b341e5ec625

[benmccown]

Just got my SP-8s in the mail today. Going to try printing the alternate top, will update on how it goes.

I watched the videos you shared. As someone who doesn't have Rexroth BTUs to compare against, how big of a quality difference do you notice?

[HuyLeKouta]

I have seen the showcase

So the SP-8 BTU can be used in the newer 50-55mm shell ?

Thanks for the re-confirmation

[efogdev]

@benmccown speaking of the steel ball version, it's honestly almost the same. I'd say Rexroth still feels a bit better in long run, maybe just more stable? Not even sure.

@HuyLeKouta yes, that's correct

edit (April 9): I've changed my mind, it's not THAT close to Rexroth. Less smooth, louder. But still, a good option.

[benmccown]

@efogdev So I printed the SP8 compatible top and I'm trying to use it with my 52.5mm snooker ball, but it seems to be sitting way too high off the sensor to detect any mouse movement. It looks like mine sits a good bit higher than the example videos you've attached in the original issue comment.

Any ideas if I've set anything up incorrectly? What ball size did you use in that original example?

Edit: I forgot to print an updated sensor cover. I didn't think about the fact that the sensor cover may have changed. Printing the updated one to try now.

[benmccown]

@efogdev Got it fixed up. The issue was the sensor cover along with me not realizing how hard you have to push the BTUs into the sockets to seat them. I had to get some sandpaper out so I could make more room to actually push them down.

[efogdev]

@benmccown glad you got it working! Yes, the tolerances are really tight, but it should be like that, because it would be really loud otherwise.

[efogdev]

Also, I assume you need the sensor cover? I'll make it soon and will update you

[efogdev]

Actually I just realized you probably can grab the sensor cover from the "57-68mm ball" version, and it will probably be fine.

[benmccown]

@efogdev I actually just used the sensor cover from the "Everything" file for the 50-55mm. Maybe that's why it was so tight?

[efogdev]

Yeah it's not supposed to be used with that cover, I'd recommend to print the one I've mentioned above. I probably should make it more clear in the README.