hemmingway kit for low speed drive for VMC mill question

Have you spoken to Hemingway? I have always found Kirk Burwell hones

and straighforward in discussing his kits

-- Myford Mat

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Why not fit a variable-speed inverter? Mine allows speed to vary from a few r.p.m. upwards. Continuous variation allows fine speed adjustment for smoothest cutting.

Yes, I spoke to Hemmingway a while back but he couldn't tell me whether the kit would fit under the existing drive cover. I presume it will but...

I am really more interested in actual owners experiences and am curious to know how well it works in practice and what the useable speed range ends up as.

Thanks,

David

Interesting idea but it is a new mill with single-phase motor and I don't really want to swap it out for another one. I might consider that approach if/when the motor dies. As a matter of interest, what is the low-speed torque like with the inverter ?

Thanks,

David

Torque remains fine down to ten or so r.p.m. This is very handy for turning: especially thread cutting up to shoulders. You can use the speed control to stop the work within a few degrees of the required thread end. Also useful for knurling under power.

I had this one fitted from new, five years ago. I've only moved a belt once since - to get a higher maximum speed.

There was an article in ME a while back to do this, and IIRC the cover would not fit over the new large pulley. The articel should be on the shelf, I'll give you a reference if I can find it.

Steve

Given the motors are often fan cooled do you get any overheating with hi loads and very low revs?

Steve

I pull the fans off my inverter controlled motors, and fit PSU fans instead. They are wired so whenever the motor is on, even if it's stalled (very low speed) you still have full airflow from the fans.

Joules

Hi,

Thanks for replying, I was already aware of the ME article and had decided not to do it that way because of the issue with the cover. AFAIK the Hemmingway kit is a completely different design but I still don't know whether it fit under the cover :-/

David

I have already pre-planned this mod too, even though my VMC hasn't arrived yet (due this week I hope) as it should give a useful lower speed for large flycutting and so on, so please keep us posted with what you find out.

Peter