Two Motors and One VFD

[Anorak Bob]

Hello All,

My mill has a 1/2 HP rapid feed motor that I have never connected to power. It had been my intention run it via a 1HP TECO FM50 VFD but that TECO now resides in the base of the tool and cutter grinder.
The mill's main motor, a 2HP Oerlikon operates via a 3HP TECO FM50. The mill's table power feeds will only function when the main motor is running.

Could the rapid feed motor be connected to the 3 horse FM50 and run concurrently with the ability to be switched on and off?

The photo below shows the Schindler rapid motor's connection details. Hopefully reconfiguration is straightforward, access to the motor certainly is not.

Bob.

374320

[BobL]

Are the power feeds performed by individual motors or mechanical connections to the mill's main motor.
I suspect the latter?

The diagram indicates the power feed motor is convertible to 240V 3P.
Blue underscore means "Triangle" indicating delta conversion suggestive of 220-240V 3P connection
Red circle shows a typical "Y" connection usually associated with 380-440V 3P connection
374323

Connection and operation of two motors to the one VFD will be more than tricky.
Both motors would need to be turned on off at the same time which besides being a PITA might not be appropriate or even dangerous.

The only setup where I have two motors running at the same time from one VFD is on my WW BS.
The 3P motor consists of two separate motors - the main 4pole 3HP motor that runs the bandsaw and a much smaller (0.2HP) 2 pole motor that drives the cooling fan. This effectively still provides substantial cooling at low RPM although I rarely run the saw at <25Hz. Both motors are of course turned ON/OF simultaneously.

The simplest solution sounds like it would be a second small VFD that would give you totally independent control of the power drive motor.

Am more than happy to give you a hand with any of this.

[Anorak Bob]

Hi Bob,
Thank you for your detailed reply. You undoubtedly explained this to me in person a while back but....:doh:The powerfeed gearbox is belt driven from the main 2 horse motor. Another VFD sounds like the only way forward.

Bob

[Stustoys]

Hi Bobs,

The guy that sold me my Teco said it was fine to switch coolant pump on and off while the spindle was running on the same VSD. Though given the price of VSD's these days I'm in no hurry to try it on my Teco. :)

[Anorak Bob]

Hi Stu,

I just had a look on eBay at the price of a replacement 3 horse FM-50. :oo: No experimenting on my behalf!

BT

[jhovel]

The advice Stu had about the coolant pump is right, and should apply for any VFD. I believe that Anorak Bob's 3 Hp VFD would not complain at all, having a 1/2Hp motor switched on while the 2Hp spindle motor is running, nor having it running on it's own. Since the spindle motor is never going to be under full load when you switch on the fast traverse, the VFD is only going to "see" a small increase in "load".
I would personally NOT add a 2HP motor to a running 1/2Hp motor though!
So set up the switching that you can't start the spindle when ONLY the fast traverse is running and you should be fine with a single VFD, Bob.


Cheers, Joe

[BobL]

There is one proviso for using two motors on one VFD that does not apply to Bob because I believe he is not interested in coolant and maybe not VFD speed control.
This relates to Stu's suggestion of using a coolant lube pump motor on the same VFD as a spindle motor and using the VFD for spindle speed control

If a single VFD is used for both motors then the flow of the coolant will depend on the speed of the spindle. In the tests on my Hercus Mill The 1/20HP coolant pump on the Hercus pumps no coolant up to the mill head until the pump motor reaches 38Hz and even at 45Hz there may not be enough coolant. A 50Hz there is plenty of coolant and above that there is heaps so the excess coolant needs to be controlled by a tap.
BUT
If you wanted to run the spindle at say 100Hz and stymie the flow with a tap I'm not sure the coolant pump motor would like to do that for too long. My coolant motor has no cooling capability as it relies on the coolant for that and all that energy spinning the impeller at 100Hz has to go somewhere and I reckon it would end up over heating the coolant and pump motor if it ran for too long.

I thought long and hard about this which is why I ended up going for two VFDs for this situation.

[Anorak Bob]

Thank you Joe.

David Samways of Anglo Swiss Tools has a video on YouTube showing a 1977 13 running. The rapids can be used either independent of or simultaneously with the main spindle motor running. The advantage of the former would be during setups where a spinning spindle might be a dangerous disadvantage.

I do have one of your ex lift door motor VFDs unemployed so if I jack the mill up to gain access to the Schindler motor I could connect it to the VFD to see whether the rapids actually function. I will speak with Bob about the remote switching of the VFD.

https://www.youtube.com/watch?time_continue=15&v=b0B-ctFRn00

Bob.

[BobL]

Bob - I had another needle in my knee so it's currently feeling pretty good. I should rest today, but tomorrow I could bring those dull mill cutters over for a play and discussions on remote switching of the VFD.

[Anorak Bob]

Bob - ...... but tomorrow I could bring those dull mill cutters over for a play and discussions on remote switching of the VFD.

You can. See you tomorrow.

[Com_VC]

Is there an easier way to get a small 3 phase motor running without using a vfd? It just seems a waste to use a vfd on a coolant pump when there is no really need for all the additional features it offers.

[BobL]

Is there an easier way to get a small 3 phase motor running without using a vfd? It just seems a waste to use a vfd on a coolant pump when there is no really need for all the additional features it offers.

It is possible to kludge a 3P motor into running using a cap and a bit of circuitry but it may then not develop enough power to deliver fluid up to the required height. Impellers are not necessarily linear devices so a small loss of power may result in significant loss of flow.

I agrees it does seem a waste to use a VFD. One alternative for my situation was to buy a small coolant (1/8HP) SP coolant pump ($118 from Hare and Forbes) but all the ones I have seen were too tall to fit into the small space I had under my mill and I did not want to locate it outside the mill base. For exactly the same $ I bought a decent 1/2HP Powtran VFD and while there was some mucking installing it, now that its done I really like the fine flow control that it provides . The other alternatives were to buy a beefy water feature pump for ~$50 like I have on my lathe, or use a washing machine water pump like I have on my bandsaw. Given the phapphing about (mainly leaks and pump rebuilds) I had with the washing machine pump i did not want to go that route again.