Technics 45 record spindle adapters

Rediscovering turntables and vinyl. Picking up used ones to explore, but they frequently are missing the center 45 rpm record adapter. I found 3 really cool ones here (out of many), but found that they variously wanted some tweaking to fit the 3 Technics turntables I have as examples, and actual 45 records. For posterity, I will record my findings of 7.28mm as the ideal center hole, and 38mm as the ideal outer diameter to fit the 45 record center hole. Also, matching two Technics adapters I have shooting for about an 8.85mm height for aesthetics and ease of grabbing to remove.

So, I designed nothing here, just remixed these fine examples to these specs for my purposes, and hopefully useful to others as well. I can't decide which one I like better!

So, these may turn out slightly tight on the spindle off the printer, but I like that so some modest cleanup with a loose drill bit (just turn by hand in the hole) lets you tune in a perfect fit, slides on/off easily, no wiggle.

I used 0.1mm layer height for a quality finish, and 1 and 3 benefit from variable layer height on the very top for an even better smooth finish. As you can see I printed on my textured Prusa sheet, which leaves a nice texture for the bottom pieces on 1 and 3; I don't like the way this looks on top for 2, but don't feel like recalibrating my first layer to change the sheet. I suspect it will look much better on a smooth sheet.

Many thanks to amiga_fanboi for educating me about concentric or spiral top/bottom layer infill, I didn't know about this and it's awesome for round objects like this!

Finally--weight. My real Technics adapters weigh 4.7g and 6.1g. I printed 1 and 2 at 100% infill in PETG, which resulted in 4.2g and 8.7g respectively. The heavy weight feels great, but this is a personal preference. For #3 I went to 50% to dial in 7.4g, I think that's in the ideal range.

I liked the suggestion to also use 3 perimeters, in case you use < 100% fill.