Need recommendation for VFD for older (1960s) mill

[Larry$]

40 years ago I built a rotary converter, worked great. I came by a used 3 phase motor on the cheap. Bought some big caps, switches and relays and spent an evening putting it all together. Worked for years before I got real 3 phase. The rotary does produce "real" 3 phase but looses some efficiency. It will work with any (?) 3 phase machine you may get in the future within it's output range. (CNC????) No programing, doesn't care if it is a multiple speed motor, will drive additional motors at the same time, instant reversing of a motor isn't a big deal.
Static converters do not produce true 3 phase they only kick a 3 phase motor over using big caps to get it spinning. You can home build the same for way cheaper. BUT the driven motor will be a lot less powerful.

 

[Weldingrod1]

Just don't shift from high speed to low speed without stopping first
Regenerative load gone...

Sent from my SM-S911U using Tapatalk

 

[6061T6]

I told the sales person exactly that. That I would not change speeds without turning off first.

But I also told him every motor will have a small regenerative load when turning off and coasting. He said that was a no-no per their literature.

 

[Chipper5783]

I have the Maho MH600 (very very similar to the FP1). I have several machines and for many years ran my shop on a commercially made 5HP RPC (the Maho is a 600V machine, so I have a transformer btw the RPC and the machine). The MH600 has a second small two speed motor that drives the feed mechanism. It sounds like the FP1 has one motor, so dialing the VFD would effect the spindle speed and the movement speed?

About 5 years ago I changed to a Phase Perfect due to the addition of a good sized CNC. The Maho performed well with either of the phase converter systems (and super easy as no modification to the machine controls).

As for instant reversing for tapping, I do this quite a bit on two of the other machines in the shop. I point out that there really is no such thing as "instant" reversing.

The CNC mill has a tap drive routine - I have not used it a lot, perhaps 1000 holes in the past 5 years (lots of shops would do that many every day). It takes about 3 seconds to go from FWD to REV (the Z feed is worked out so that the vertical position is managed, I use a tension compression tool holder, but no problem with even #8 taps). I also have a large drill press that I modified to a VFD drive and added a foot operated reversing signal into the VFD - the rate of speed change for the VFD is programmable - I didn't get real aggressive on it, I set the reversal at ~3 seconds. I have tapped hundreds of holes, works great. I don't see any need for a real hard/fast reversal (perhaps to get that tap in and out 0.2 seconds faster?).

The tapping head will probably be faster because it likely has a faster speed on the retract. I know on my Maho, the Z axis head room is very limited so a tapping head would not be practical in most of the work I do. I love the little Maho, but the short head room pushes most tasks onto one of the larger machines.

 

[mksj]

A motor that is stopped, does not have a regenerative effect. I wish they were more transparent as to the starting capabilities of their digital phase converters. If it say it is a 5 Hp unit then it should be able to start a 5 Hp motor, otherwise they should clearly state the amperage/motor rating/load condition similar to what you see with VFD's which is variable torque, normal duty and heavy duty. In another forum a gent had a 3 Hp lathe with a 2 speed motor, I recommended the 5 Hp PP, he bought the 3 Hp PP and of course it faulted out on acceleration. The tech. at PP said it was a difficult load to start, a mill should be even less of a load, seems like when they rate their units its for variable load like fans and pumps. So back to the RPC or VFD, the commercial turn key RPCs are quite expensive relative to the a VFD up to 10-15 Hp range.

I still have some concerns of wiring in a VFD to this machine without having a wiring schematic and a look at the control box. There are also overload and interlocks to deal with. Essentially with a VFD you could eliminate most of the electrical cabinet components. Wire the VFD output directly to the motor pole changing switch. This mill is not made to run in reverse due to the clutch system, and tapping you do not need such fast speeds for stopping/reversing because you are running at very low RPMs. Advantage of a mechanical clutch type is it is based on load, although I haven't used them on the mill. I installed an automatic tapping setup on my miill which is done with sensors and controls the VFD start - reverse - stop points.

 

[RickKr]

.

 

[6061T6]

I would gladly get the 5hp simple phase perfect if it was guaranteed to work. And save myself all the rewriting hassles.
But unfortunately the manufacturer will not stand behind their product. Maybe if they had a decent return policy….

 

[Chipper5783]

I spoke to Phase perfect today to enquire about purchasing their simple converter (5hp) They were not comfortable recommending this version because it has a 2 speed motor and regenerative load that it may produce. They directed me to their PTE007 which costs $2500.

At this point, it no longer makes economic sense to go down this route. I am also not convinced of their reasoning. Doesn't every motor produce regenerative load? What does a 2 speed motor have anything to do with it? If indeed the PTS005 will be satisfactory, I didn't like that they wont stand behind that product and want to unnecessarily up sell me.

That seems very odd that you have to up size the 5HP PP because the target load is a 2 speed motor, only 2HP! I am using a 20HP PP (my largest motor is 15HP), the vendor assured me that the 20HP unit was rated for starting a 20HP motor. Being a 2 speed is nothing special - especially on the higher speed (the low speed is probably a second set of windings, could be something weird like consequent poles - again not particularly difficult to power). If the Deckel is anything like the Maho, the vintage German wiring was very nicely done (my electrical cabinet is a work of art) - seems a shame to gut it, and quite a bit of work.

Recommend doing a bit more work on the PP, what the sales guy is saying doesn’t make sense.

 

[matthewsx]

Sometimes you just get the wrong person on the phone.

But, a rotary converter will do the same thing for a whole lot less. The machine really doesn't care where the power comes from as long as it's the right voltage, amperage and phase.

John

 

[6061T6]

I think the tech sales guy was just trying to be a good sales guy by attempting to up sell me.
A few more email exchanges and now he feels the 5hp unit will be fine.
I am inclined now towards the PP unit as it will save me some work and keep the Deckel as original as possible.