Re: CNC Mill Transformer
 

I had heard (as apparently we received the exact same machine from the same sponsor here at RIT) that it was actually .001" that it would drop. Either way, I don't think it's particularly important what the amount it drops, simply that it drops somewhat and wasn't really suited to the application that the sponsor attempted to use it for (which is why they decided to donate them).

Matt

Re: CNC Mill Transformer
 

What is this? Sign up with us and get a free CNC? I want this sponsor! (to all of our sponsors reading this note that we love you guys and wouldn't trade you for an warehouse of CNC machines.... honest....)

Re: CNC Mill Transformer
 

Back to the installation of the mill weather or not your electrician brings it up you could check to see the price to get the motors rewound to operate at the 208. Also keep in mind that you would need 3 transformers, one for each of the phases to boost up to the higher voltage, this coming from myself and my dad in the background, whom has worked with industrial controls and is a master electrician by licence with 25+ years of experience. Get an electrician from a local contractor, then you will be sure to get one whom is licensed and insured and no a lineman or maintenance man as most are in factories.

As is often said please consult a qualified professional.

-Mike Aalderink, Electrician of over 6 years.

Re: CNC Mill Transformer
 

I know for a fact that the type of tolerances you're quoting are indeed valid for a VMC in a production-line setting (e.g. 200 pieces/day, loaded by a robot, high-speed material removal, shop floor environment, etc.). However, with the proper measuring apparatus, and the proper machine, and the proper tooling, and the right conditions, significantly better tolerances can be achieved (as in, an order of magnitude, or better). Diamond tooling and laser interferometry, in combination with a very stable machine can produce complex compound surfaces with tolerances of several microns (of which two microns might be a significant enough portion to worry about, if it would cause a higher proportion of rejects).

I'm not saying that this machine can necessarily do this, because I haven't consulted the manufacturer or the previous user for its specifications; I am saying that there exist similar machines which can, and that minus the fantastically expensive custom tooling, fixtures and metrology equipment (e.g. laser interferometer, etc.), it's conceivable that a small, used one like this could be worth $100 000 (USD). (And I say small, because the ways don't have much travel, the workpiece size is rather limited, and it fits in about the same space as a regular manual knee mill. To clarify further, I was being slightly facetious when I called this "just right for a FIRST team"; it's overkill, I know. If only there was a :facetious: smiley....)

Now, if Matt is correct, we might as well forget this side issue....

Re: CNC Mill Transformer
 

Matt,
This is also another number I have heard. In either case, it won't cause us to throw the machine to the curb. Now for the details on my progress today. I have contacted a local distributer and he gave me a number I could call nationally for service. I contacted this individual who told me where to look inside the electrical panel to check the actual transformers to see if we could wire it to 208V. Nope the primary voltage is (380/400/440). So now I have put in a call to our sponsors to see if they have any transformers laying around. Hey it never hurts. Worst case I will contact a few local electrical distributes to see about a quote. I also ha a co-worker contact a local power company he worked for to see if they might have anything we coil use. Nope.
I sure am learning alt from this.

Re: CNC Mill Transformer
 

Rees,
I think you are getting closer to the info needed. If you know for sure that the machine will only input 440 VAC 3phase and it requires about 10kVA input that is sufficient for an electrician to get started looking for a transformer. He will know that a 480 to 208 stepdown transformer can be turned around and used as a step up the other way and the kVA will get him into a family of transformers that will work. Expect a box the size of a small desk and weighing several hundred pounds to be stationed somewhere close by. If the power vault is indeed in the next room, that might be the best place for the transformer. (air cooled models are the best for your application) A custom transformer is not needed, there should be off the shelf devices that will do the job. He will likely do this anyway, but you want to make sure that the wiring is water and oil resistant and well grounded. Congratulations on a fine acquisition.

Re: CNC Mill Transformer
 

I apologize for not stating a question in my first post. I made it during a class in school that rees2001 was teaching and i didn't want to take up too much time so I neglected to reread it, and i i figured that people would be able to figure out what I was talking about.

Now i wish i could have found that PDF for the mill I looked for over an hour and couldn't find anything.

The reason that i called to get a quote on a custom transformer is because rees2001 and i searched all over the internet for one that would be sufficient for our use and couldn't even find one close.

Now that we are closer to get it working we have to learn how to use it which should be a trip.

Re: CNC Mill Transformer
 

For anyone interested here is the up to date progress. Yes I have been working on this for over 1 week now. Our school electrician came by & we opened the electrical panel and looked at the manuals. Between the 2 of us we figured that depending on the wiring we can hook this directly to our 3ph 208V. The transformer built into the machine has a number of different wiring configurations. I called Chiron for the ... who knows how many times & the guy I talked with told me that "yes, depending the wiring configuration we can hook it up to 208 & it will work." I have asked our sponsor to have an electrician more familiar with machine setup come out & verify our hookup before we run the machine. So, thanks to all that helped, because of your help we may be able to save about $1000.

Re: CNC Mill Transformer
 

That is great news, just the kind you want to hear.

Re: CNC Mill Transformer
 

Ive seen enough misinformation in this thread, it makes me almost sick....
First, I worked in a CNC shop this summer, so I actually have hands on experience working with these machines, it isn't just something I read somewhere.

Ok, about the dropping of the spindle when you lose power, after you turn the machine back on, you re-home the slides. So the spindle dropping would not be an issue. However the better machines I worked with didn't even need that. If there is any doubts at all it takes a full 3 seconds to zero the slides :p Especially on a machine that small with a rapid that fast.


As for tolerances, I'm not saying that 2 microns is something that isn't achievable, but for a $100k machine ...no... I would expect to see the machine be able to go down to .0001" but that's it. As for actual working tolerances... unless your building something that is using multiple pressed pins for holding together 2 pieces, you wont even notice .005" difference. as for measuring down that fine... I would like to see equipment to measure down to 2 microns, for larger pieces... we had a small digital height gauge that went down to 5 decimal places, but that small, tip diameter becomes and issue.


oh and,
Trust me, that is compact. Compare that to a horizontal machine, 11 pallate changer, 240 tool changer, 19.6x19.6" travel, 20,000 rpm spindle, up to 1000 ipm feed rate (feed, not rapid). Yes, that is a compact machine.

Oh one thing that I dont know for sure though, I thought the servo motors on the CNC used DC, not AC, and the power input was rectified, and then fed to the servo amps.