Hi Guys,
I have done quite a few searches on the forums trying to see if there is any specific advice regarding the merits of a transformer vs vfd with voltage doubler, and I haven't really seen specific advice, so here goes:
I am assembling a cnc router for a high school robotics team to use. We cut wood prototype parts, and polycarb/6061/6063 "production" parts.
The gantry is a shapeoko xxl (belt driven xy, ballscrew "hdz" z axis). Not ideal, but the "price was right".
In reading posts here, it seems that one should steer clear of the 120v spindles. So, I have purchased one of these:
https://www.amazon.com/gp/product/B077BY1L86 which seemed to be a good combination of: not too much power from mains, 240v instead of 120v, and not too heavy (9lbs instead of the typical 12lbs). Assuming that these specs are in the right ballpark (always questionable, which is why i ordered through amazon), I now need to figure out how to drive the spindle.
Realistic/Ideal situation is that I will have access to 240v single phase mains, when the robotics team moves to a new build space (we are currently shopping for warehouse space and hope to have a new manufacturing space in the next couple of months). In the mean time, I need to run this spindle from a 120v 15a supply (certainly NOT ideal).
Further complicating things is that I would like to, occasionally, take the machine on "field trips" in a trailer to other schools to demonstrate cnc machinery, where likely I will have access to 120v 15a mains. The machine itself is being built into a table/enclosure with casters to facilitate easy movement and the abuse of being trailered around.
With all of that setup, here is my question:
Does it make more sense for me to:
1) buy a VFD with a voltage doubler, such as a
https://www.amazon.com/Huanyang-Vari.../dp/B07GD628D7
OR
2) should i use a step up/step down transformer, and get a straight 220v to 220v vfd, such as this guy:
https://www.amazon.com/HY-HUANYANG-V...p/B0775S7KFW/?
of note: I happen to already own an older version of this guy:
https://www.powerbright.com/product/vc2000w that is not being used for anything else, and so it is "free" to me.
OR
3) is there another option that I haven't considered?
My research so far seems to indicate that transformers should be 95% efficient or better, but I dont know about the efficiency of voltage doublers, or if there are any other considerations other than just efficiency.
And then as a follow up question: What other considerations should I be thinking about? Should I be setting the current in the vfd for each phase to a lower number when running off of a 110v/15a mains, in order to not overload the 110v mains? Should I be worried about supply fitering, or mains contactors for the table/enclosure that the machine will be in? Other considerations I should be thinking about when running the machine in the student environment?
Thank you so much for taking the time to help out a noob.
Austin
Robotics mentor