The anodising looks great. How much did it set you back?
Final status report for New Year's day:
I believe I have finally won my battle with J2 Spindle, I was able to get it mounted on the lathe and centered well enough to bore a little out of the inside, now the stepper shaft has a nice snug fit.
When installed, however, the J2 motor needs five washers, not three, to keep far enough away from the J2 gusset for the set srews to clear the motor. No biggie, I have lots of M4 hardware. Swapped the silver nuts for black ones while I was at it.
Photos below.
/Mitch.
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_23.avif
progress !
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_24.avif
progress !
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_25.avif
need 5 washers for proper spacing.
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_26.avif
set srews now just clear the motor
Greetings Chris,
It's possible that the anodizing killed the threads, but it didn't affect any of the the other M3s there. Andoizing does add thickness, but a very small amount (under a tenth).
I think my J2 spindle is possessed.
Looks like I need to take it off *again*. The bore for the motor isn't big enough for the stepper shaft. I could probably "force" it but I won't. Given all the things wrong with this one part, I am wondering if I got a bad one.
So, J2 spindle is headed for the lathe again, I hope I have a boring bar long enough to get in there from the flanged end, since that'll hold more true in the lathe chuck.
So for J2 spindle I've had to : turn down the OD, tap the holes, and now turn the ID for the motor shaft.
I might need to pick it up in the morning. Since I took the little powder coat oven out to heat the bearings, it's a good opportunity to powder coat the guitar pedal my son built while home from school.
/Mitch.
Thank you for the heads up. I just went through my stock and all appear to be tapped. Im sorry about the hassle on that. Is there any chance the anodize has filled the threads? I'll send a message to my vendor and make sure this is double checked on the next batch. Build looks great BTW - keep the pictures coming. Its cool to see it come together.
Wow, that J2 spindle is a real troublemaker! :-).
I turned it down in the lathe, then found out that the non-flange end is not tapped for M3. You might want to check your newest batch to be sure the vendor did not miss it.
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_27.avif
Setup for thinning
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_28.avif
Done, fortunately this will be hidden.
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_29.avif
So *that* is why the screws won't go in! 🙂
The J2 spindle is putting up a fight to get the 30206 bearing onto it. Trying a more extreme temperature difference, but I may need to throw it on the lathe to turn it down a little.
Assembly has been smooth so far ....
Awesome.
Happy New Year All!
I'm making good progress on my build; after a little research and some experimentation with some other anodized parts, I tried the heat expansion technique. I only raised the housing temperature to 150F and dropped the bearings to 0F in the freezer, and it dropped right in.
Therefore: You don't need a huge temperature difference to get the bearings to drop in. No damage to the anodizing.
I may need to disassemble partially as my limit switches aren't here yet, but I hope to make significant progress today!
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_32.avif
3D printed arbor to press bearings in; wasn't really needed
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_33.avif
Bearing installation going smoothly
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_34.avif
so cool.
Looks like, at least for my aluminum kit, the hole for the cut-off square head M8 screw is not tapped in the J1 Platform part.
You might want to check other kits if this is not a known issue.
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_35.avif
Missing tapped hole
Hmm. Looks like I won’t be able to heat the material to get the bearings to fit. Heating anodized aluminum will cause the finish to crack since the coating is brittle.
Therefore I’m printing a tapered jig to mate with the cup and will attempt to use an arbor press to get it in there. Might still freeze the cup.
You say the fit is a light press fit, has anyone used a press or have all used heat and cold?
/Mitch.
Tough choice, those both look nice. Can’t wait to see it complete.
More printing underway tonight, attempting to print both J5 side spacers at the same time, we'll see what happens.
Meanwhile I have cut the flat covers out of acrylic in both translucent green and smoked gray. We'll see how well they work, if they don't flex they won't break, but the holes are so close to the edges that the acrylic might not hold up.
I love the translucent green stuff; the photos below don't do it justice but the material seems to pick up just about any ambient light and it glows along the edges. We engrave the sponsor panels on the students' robots with this stuff and sometimes the robot inspectors tell us to turn the sign off :-).
I might just use the smoked gray though, it seems to look better than the two tones of green.
Once all the 3D printed parts are done I think i'm ready for some real assembly!
/Mitch.
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_36.avif
translucent green
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_37.avif
smoked gray
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_38.avif
Edge glow
Hi Mitch the limit switch tip is in the download for AR2 print files on the downloads page. I was just about to reply to your email and I will also attach this file for you.
I think the color scheme is going to work 🙂
I have access to a laser cutter, so I might cut the flat covers out of translucent green or solid black 3mm acrylic. Printing a 1/8" thick flat plate's going to take a while compared to the laser...
I've got this neat translucent green that will show the mechanisms inside; if that doesn't look good the solid black will go with the anodized material.
Onward!
/Mitch.
https://anninrobotics.com/wp-content/uploads/2025/07/Mitchs-AR2-Build-Log_39.avif
green with black
