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FP1 electrical box re-cabling

Rich L

Hot Rolled
Joined
Sep 24, 2006
Location
Colorado
When I first got my FP1, I had one hell of a time unloading it from a trailer with a good part of the difficulty coming from the fact that the electrical box was connected to the mill via two non-disconnectable cable conduits. Indeed, it was possible to disconnect the wires from the terminal block inside but I endeavored to muscle the two pieces around without doing that. This mill is 1967ish and throughout its life the conduit was stretched and the internal wires were showing through very clearly. I vowed that sometime during my ownership of the mill that I would devise a way to decouple this box to make transport easier. Well, after several weeks of slow-roll assembling parts, I finally embarked on this task and it’s coming together nicely albeit not done. The smoke test is soon but I thought I’d share the mechanics (or electrics) with y’all.

The connectors are high quality DMS plugs and sockets, Wiring came from cannibalizing some 12-3 and 12-4 SJ cable (a lot of same and unconventional wire colors but all are marked and labeled and recorded). Cable sheathing is just some expandable audio cable sheathing I got from Amazon. The four red wires from the mill body were cut and butt-spliced to new wires ending in the new 4-pin plug. The motor wiring was straightforward and that cable ended in a 7-pin plug. Now I can transport the damn thing without dragging an electrical box "pig" along with it. I know some folks have adapted a VFD to their machines but I wanted to keep this electrical box around; as dirty as it is.

I also used the original conduit "ends" even though they are sized and threaded to an old standard. The flexibility of the sheathing I used enabled that. The old conduit had a nominal amount of stretch resistance and my new sheathing has none but I intend to unplug the cables to avoid any stretching and wire stress.

(sorry if these pictures come out too small - I don't know the trick to make them bigger.

Cheers,
Rich

PM 1.jpgPM 4.jpgPM 3.jpgPM 2.jpg
 
Which motor terminals did you use and are you using only one speed button? I'm interested in how you wired it up.

Cheers,
Rich
 
Which motor terminals did you use and are you using only one speed button? I'm interested in how you wired it up.

Cheers,
Rich

Just finished the VFD wiring on my machine,(an early 60s vintage US Spec lever type) so the info is sitting on the coffee table next to me.

I tied the Big Box terminal board motor lines 13,14 and 15 together (Us, Vs & Ws on my Siemens motor). Wired the remaining Motor leads to the VFD terminals. I aligned the Ub, Vb, Wb motor leads (10,11,12) on my board to the corresponding U,V,W terminals on the VFD and it ran the correct direction. This wiring runs the motor at high speed. Reducing the the VFD drive frequency to 30hz gives the half speed. Start stop can be managed on the VFD if you like, or you can wire the machine monetary switch. I wired my momentaries to the VFD and use them to control start stop.

I buzzed out the big box at both low and high speed settings to confirm the motor wiring. Your machine is later than mine and might not be wired the same, so good to check it.

My big box is going under the house.
 
OK - I'm trying to picture what you did ... Did you essentially jumper all three motor terminals Us, Vs, and Ws and run the other three lines Ub, Vb, and Wb to your VFD? Why did you need to tie them together? I'm not familiar with VFD's that have terminals for momentary start/stop but you must have that. I'm really not worldly about more complex VFDs, anyway. I just have a simple one that runs a grinder and, indeed, it may have capabilities I don't know about.

My Siemens motor terminals are labeled Ua, Va, and Wa; and Ub, Vb, and Wb. Same general setup, I presume.

Thanks for the info, though! I'll think about that some more.

Cheers,
Rich
 
Ah, OK. I had no idea my motor was being configured that way. Thanks!

Certainly not intuitive.

Again, I would buzz out the box to verify yours is wired the same. My older machine has a rotary switches for both the main power and for changing the speeds. It has only one contactor for main power control which I jumpered so I could verify how the input power was routed to the motor for the high and low settings and see which motor connections were jumpered together. I see that the newer machines use push buttons so I'm assuming additional contactors.

good luck!

I'm very new to VFDs but it looks like they offer some nice features. In addition to not having to find a place for the big box!
 
Well, I'll be ... Picture from the inside of the Siemens motor cover. As you might imagine, I saw this the while doing my re-cabling but it didn't dawn on me to think about the VFD option. I just did wire-to-wire rewiring. So, to do what you did, I'd jumper Ua, Va, and Wa and hook the "b" wires to the VFD. That would, as you did, connect the motor up in hohe Drehzahl (high revs) and allow the VFD to control the speed. Evidently, the push-buttons on mine energize a relay that makes the "a" connections. All done in the infamous "Polumschalter"

motor speed winding connections.jpg
 
My FP1 too came with a cabinet and a single voltage 440V motor. I did get rid of the cabinet (and actually used the enclosure for an electrical control box for a shop extension) but getting 440V for the mill was somehow complicated, so I got a 240V TEFC three phase motor (as most of the machines in the shop) and added a VFD to have an additional speed control. I've replaced the original FP1 run/stop switches with two on/off push-button switches wired to the VFD remote control terminal. I am using the green switch for forward/stop, and the red, under a swing cover, as reverse/stop. This I use almost exclusively only when working with the TREE boring bar to retract the cutter during facing or taper boring.

fp1.jpg fp1-1.jpg
 
Well, I'll be ... Picture from the inside of the Siemens motor cover. As you might imagine, I saw this the while doing my re-cabling but it didn't dawn on me to think about the VFD option. I just did wire-to-wire rewiring. So, to do what you did, I'd jumper Ua, Va, and Wa and hook the "b" wires to the VFD. That would, as you did, connect the motor up in hohe Drehzahl (high revs) and allow the VFD to control the speed. Evidently, the push-buttons on mine energize a relay that makes the "a" connections. All done in the infamous "Polumschalter"

View attachment 254447

That would have saved some time!
 
My FP1 too came with a cabinet and a single voltage 440V motor. I did get rid of the cabinet (and actually used the enclosure for an electrical control box for a shop extension) but getting 440V for the mill was somehow complicated, so I got a 240V TEFC three phase motor (as most of the machines in the shop) and added a VFD to have an additional speed control. I've replaced the original FP1 run/stop switches with two on/off push-button switches wired to the VFD remote control terminal. I am using the green switch for forward/stop, and the red, under a swing cover, as reverse/stop. This I use almost exclusively only when working with the TREE boring bar to retract the cutter during facing or taper boring.

View attachment 254470 View attachment 254471

Like your machine color. Mine is battleship gray at the moment, repainted from green. Your machine is only about 1000 SNs earlier than mine so I think your color would be appropriate. My slotting attachment is already that color. On the very long to-do list!
 








 
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