I wasn't sure I could machine the J4 timing hub but I gave it a shot anyway. The timing belt does engage but seems to slip because the teeth are too shallow (my smaller endmill that can go this deep is 1/8"). So I resorted to 3D Printing the part for now (until I get a 4th axis :))
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_20.avif
And this is J4 Motor mount limit arm - 3 OPS and routine toolpath with good ol' rectangular parts you can hold in a vise.
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_21.avif
And while the CNC was busy I was able to progress a bit the assembly, motor for J2 and arm in place.
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_22.avif
This part - the J3 tension ring gave me a hard time - final thickness is 2mm so work-holding and order of operations are critical.
I ended up using both CA glue and tabs
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_23.avif
It worked great but I failed a few times before this result 🙂
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_24.avif
It took 6 ops for the J4 turret housing but I am very pleased with the result - one of the cutest parts I machined
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_25.avif
I'm now machining a busing in order to broach the 5mm key on the J2 spindle.
Next I'm going to focus a bit on the assembly and try to put J2 together this WE.
While the CNC was busy with J3 spindle I could run the lathe and create most of the features for J3 bearing cup. Then run a final op on the CNC for the hole pattern
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_26.avif
Last but not least I have been trying to machine J3 tension ring but the part is so thin (2mm) that the CA glue work holding is not working and sent the part flying twice in the mill - I am going to find an alternative method - stay tuned
On the right is the first attempt at J3 spindle - this is what happens when you don't verify your tool stickout in CAM Vs real life....
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_27.avif
After the necessary correction and 3 ops + 1 broaching later here is the finished part
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_28.avif
Here is J2 Motor Support, the part was 90% done and the last drilling operation was very tricky and the bit wandered and ended up breaking. Had to scrap the part and restart !
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_29.avif
Last but not least I'm taking some liberties with the design of the covers - the J2 cover will keep the AR3 logo but I added a shark to the J5 cover
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_30.avif
The J2 spindle was a bit more complex that I thought initial;y. I had to alternate lathe, CNC OP1, lathe again and CNC OP2 and 3
But the result is great - neat little part. I still have to file the key way square and tap the holes but 90% done
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_31.avif
Moving on to the second join, the J2 tension ring was a bit tricky to machine due to the thin thickness, I used the CA glue work holding method and it worked great
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_32.avif
I didn't have a 5mm broach so I opted for machining the bulk and cleaning the corners with a file - this is no Clickspring quality but it worked
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_33.avif
And finally I was able to do some assembly - J1 mechanically completed !
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_34.avif
I went the broaching way for the first pulley (let's see if I can keep it up for the 5mm...) - first time broaching and it went surprisingly well
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_35.avif
And now J2 ARM - very close the to limit of my CNC envelope, this is OP1
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_36.avif
And the finish part (3 ops)
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_37.avif
Next was J2 turret housing and this part really challenged me. I did offered a fresh end mill as a sacrifice to the gods of CNCs but that wasn't enough. I had the part fly off because the superglue work holding wasn't strong enough (or not enough surface in contact) for OP2.
I had to become creative with the setups and the tool path containment.
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_38.avif
Overall it turned out all right, I blew the side of the part when I drilled for the countersink bolts but that's a small price to pay for 6 setups and over 2 hrs of machining time due to less than rigid setups.
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_39.avif
While this was machining I was able to press the bearings into J1 with the help of my new shop oven. In retrospect I should have machined a die for my hydraulic press rather.
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_40.avif
And the parts fit together
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_41.avif
Quick update, today I was able to work on the J1 turret platform, pretty straightforward setups with OP1 doing most of the features
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_42.avif
And the other 3 ops are for removing the hat and drilling the holes on each sides
https://anninrobotics.com/wp-content/uploads/2025/07/AR3-in-Florida_43.avif
