Thread: my first mill

I've been thinking about this a little lately.
Now if I'm not wrong, these motors are parallel star, series delta right? wouldnt it be possible to re wire whats there to parallel star, parrallel delta? That would give you one 240V speed and one 415V speed. If the parrallel star(415V) is the high speed it shouldnt matter much you dont have full power?

Of course there is a fair chance I'm wrong.

Stuart

hi thanks stu and bill. im a little confused. that's normal.
well at least i got a vise for the mill today.
I think the highest speed is 1450 or something like that.

i didn't get any of the extra gear with the mill apparently
they gave it all to the guy who brought the gillatine.

here is some photos of the motor name plate and electrical connections.
im not shore which way to play it yet.
i think connecting 3 phase to the house would be the best but most unlikely
at the moment i think the motor runs at 718 low speed and 1430 higher
speed.
any way lots to think about.
SAM_0898.JPGSAM_0899.jpg

here is the vise i scored tonight thanks to thorens.
SAM_0896.jpg

aaron

Aaron,

The motor plate info shows it's a 4 pole/8 pole motor, which would make it easy to replace with a 1440 rpm (4 pole) 3 phase motor that can be wired for 240V and run via VFD. That said, it's good to keep all Deckel original equipment if possible because it is top quality, and the original motor is sure to be dynamically balanced etc.

Stuart,
Your thought on running the motor on 240V in "parallel delta" is interesting, and I would love to try that but only on a "spare" motor - don't have any ATM. I suspect that there might be a problem of current direction in the winding segments which could only be fixed by bringing out both ends of each winding segment and setting it up externally, but I'd love to be proved wrong.

Cheers,
Bill

Hi Bill,
I'd say you're correct about needing to bring out at least three more wires, splitting the delta series at the mid point.................but I wouldnt know.
I have a motor I could test, but there are three problems.
1 I dont currently have the gear to do it
2 I currently lack the time
3 I have no way of testing the result. I'm pretty sure I could make it run..... but thats hardly useful info unless I know how much power its making. Anyone seen plans for a DIY sub 5hp motor dyno? (like I need another project lol)

The only good news I have is if I am reading the plate correctly the series delta is the slow speed??


Stuart

thanks again. it would be good to use that motor but i think ill just look for a good quality
3 phase motor that i can run on a vfd.
im not shore how many kw the name plate says. is it 1.4 kw. so maybe a 2 kw motor
to help deal with any lose of torque.
i have a friend that has a gocart dyno sturt. not shore what those motors are rated at.
im impressed buy what you guys know about these motors.
what do you think of the little vise.
bill did you get my pm?
aaron

Hi Arron,
I'm not so sure you'll be happy with a single speed motor*. unless you can change the pulleys so 75hz = your old belt speed in high and 37.5 = your old belt speed in low and as you say fit say a 3hp motor but use a 1.5kW VSD (or a larger VSD that you can limit to 1.5kW)........ that might work.

You could try it as is and see what you think. I run a few motors this way(though no 2 speed ones). Though if I recall correctly Bill tried this with his Arboga and wasnt impressed(though his motor was about half the power????).

Originally Posted by azzrock

im impressed buy what you guys know about these motors.

Well its currently a theory. lol

No idea on the vice, just how little is it? the square drive looks pretty long so I assume thats because the vice is pretty small?

Stuart

*normal motors and normal VSD's. I'm told you could buy a VSD motor and vertor drive that would do the job. but then for that sort of money you could get a 240 to 415v VSD.

Hi Stuart,

I think what you are saying is that it's most likely parallel star (4 pole) for high speed and series delta ( 8 pole ) for low speed, so to wire it for 240, you'd have to work out how to wire the delta's in parallel. That might not be so easy if the center points of the groups aren't brought out to the terminals.

While it wouldn't be my normal recommendation, What about a big (2.4kw) 240 to 415 single phase transformer, and then a 415 single phase vfd. Might be cheaper than rewinding the motor..

Regards
Ray

if i add it up i a motor and vfd connecting 3 phase might not be a bad idea.
cost wise.
ill have to have a look at the speed range of the machine.
the vise is small just like the mill.
aaron

Hi Ray,

I'm not sure what I'm saying, as above, its just a theory
By the look of the picture there are only 6 wires, so yes it looks like the center points would have to be brought out. (but maybe they are joined at the lug on the terminal block? though I'd be guessing thats unlikely.)

My theory also states that bringing out the middle point of the series delta is already half done for you. You just follow the three switched wires back to where they split in two. Like finding three star points on a normal motor but you have a wire to help guide you. Then the tricky stuff starts and my head starts to hurt.

I've not given any thought to what would be needed to switch between parallel(series) star and parrallel delta.

I have a 2 speed motor here that I would like one day to run on 240V one way or another.

Hi Aaron,
You must have a cheap sparky! Still if you can get it done that would say some stuffing about.

Stuart

well i haven't hit any of them up yet. id say it would be $500 in parts and cable.
im not shore what the supplier charge but ill have to add that.
then pay or bribe beg a sparky to hook it all up.
aaron

limited speeds
I see what you mean about not being happy with the one speed range.
the machine plate say the rpms range from 1900 to 50.
with a lot of my hss tooling i may want to run the machine lots in the
lower end of the scale.
what to do.
maybe as suggested i should for know make a two speed pulley
ill have to pull the guard of to have a look.
lable.jpg

Hi Aaron,

I'll have to let us know what the sparky has to say...... I was told $750 each(I think it was) for two new panels just for starters(but that was a long time ago)

Must say I didnt think about step pulleys, but if you're talking about my comments I meant find one pulley mid way between the two speed ranges so you run at 75hz to get high speed and 37 hz to get low speed (rather than use the pulleys you have and try and use the motor either 50 and 100hz or 25 to 50 hz*). Step pulley would be great if you can make it fit.


Stuart

*as I understand it most motors will be making little to no power a 100hz. At 25hz the best you could hope for is half the power, which is about what you'd get leaving the 2 speed motor wired for 415 and running on 240V(at 50hz)anyway..... I think

Aaron,

Some posters on PM seem to be happy with running their FP1 with a single speed motor on VFD, even if there is less power on the 60 - 600 rpm range. The approach seems to be to use a motor that would normally run at the higher of the two original speeds (for you that would be around 1440 rpm) and use the VFD to halve the speed as desired to give all of the speeds shown on the plate.

Using the gears, that would give you full power for the six steps 120 - 1200 rpm (horizontal spindle), and reduced power for the 6 steps 60 - 600 rpm. My feeling is that on the (probably rare) occasion when you were on reduced power and needed more, the next step up or down would give it to you, the only exception being the lowest speed. And as you mentioned before, you could substantially reduce the power differences by using a bigger motor (2.2kW?).

It seems to me that this would save you dollars and complexity in setting up.
I'm thinking about this for my situation as well.

Cheers,
Bill