Now that the turntable base has been cast, it's time to machine the features to make it functional. I started by setting it up on the milling machine upside down with spacer blocks underneath, and clamping through the middle. In this setup I faced the bottom contour.
Here is a closeup of the finish, now the base will sit flat for the next setups.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJay16t-C0iKurTYBdTFed7x4Bd-q_HE9mXyeEwfcx7O1ajtF8bAzJy7hIIUJUm1fJxsM1j3_pzKP_IKX9MfxZdQezzwBNTXMOO2-I3r_9OALUl44o7J9-ttDm-wKFqHGn51en7oXnmRk/w640-h480/002BottomFinish.jpg)
I mention in the platter segment that I revised the spindle design to use bigger bearings. This meant the original bearing boss casted directly into the base wouldn't be large enough. Therefore, I had to make a bigger one and attach it into the platter support platform. Here I've started the first side in the lathe.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7sSwwvzRp2hDf75BpL9n731XRQElxgpTRraHutBRCcuBMol6JkXRFUqGRhqkmM4PdEmYwcZcKYk0c7x8VN7MfyAz6RmIsEJrrxZCtiHbFUbpwMsZsxX_t1c_TvpGUYUFU_na_pr1bafQ/w640-h446/003Bushingbottom.jpg)
Then machining the other side. I didn't have two identical bearings, so the bores were different sizes.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBLFdNEM5Fm4rlr9uWmKjiC8CtglQfnPvbuDPEXFrj-raZCdNptUgpdIpHwOitjxd2a8K83ZAHf8Y2QZex2XOIb5VFedjw-fVs_Zoi__5n6nigSa26z-eWliYqlRQL5Khbw8o44_JlGIg/w640-h486/004BushingTop.jpg)
Next, to mount it in the base, I began machining a hole where the original boss was. I started by plunge cutting a rough circular shape.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCVypkZw4G-Otg9-CzUgcH4_j_U1pWsM7omVf4Hc6pJy2Y9tZ3zoZxeErTAg1XjgDS03F5baSyRiLR-MyPwLIhcnLwCV_YkMLBTPDw7cx1rQI-BprjGovgt9GonIVfUORjVdw4JrdrbkA/w640-h480/005PlatformPlunge.jpg)
Then I used my big Criterion boring head to machine it smooth.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8B5kQdHIlkpgvYJTiR4qEiahJO4pRjaKCsw3N4Peik9JSTqt444a49LvAjnLlccnSCLdH_mHNICDmPNzU6ExjUlueB2Fe_vyRXn6Fif5J-V2AXfcHHbp_z6QxWlhvfKpRau_n6mYASyg/w640-h508/006PlatformBore.jpg)
To mount it, I drilled and tapped three 5/16" holes. I also faced the area around the bore so the new bearing boss would sit flat
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9McH_rWFsbl7m3JyCGabcD24OKywzq7wGrzisf1Q-pk1tnRlrCUhYuIEgNFfn-e48GPyBByzfBYyJdC6gELirp5TsubUgQNaEiS4Ny19NoxgltTbJzWNfBR4krpfMBhD6mRS_XB1n_K8/w640-h480/007Drill3HolesSpotface.jpg)
The new boss mounted.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRS9uaUu-i4HmAku9JqO4ftr3XxuBaAfgwTFPrnZKaeifCswySLRwxFSM9nqN2y7HY8h0yprSMchidw3Ejpv3Bzzs6nx6Qx8xTI9oBVMHk2M4Sqp1bzuf9gzZlmf1QSfjzxc7TfhqvR_4/w640-h480/008BushingMounted.jpg)
Lastly I faced, drilled, and tapped a 1"-20 hole for the tonearm bushing.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_8Lwgs3V1OYu-z3tP6qLYpsy_cuM8iXr7GnaXKCSwEPNzlPSfTiTABqMH6zffVZcpehsdgQZTrB26xSCEv4yDSrpdDOvwy0lPbAWyBYZydDAFyfjAydKP40keJhOgrpQgdp-1coVBGB0/w640-h480/009TapTonearmBushing.jpg)
Next Step - Casting The Platter
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