VFD enclosure.

Daniel Macina

Well-Known Member
So I know that a nema 4 VFD is ideal in a knifemakers shop but if you had to use a non nema 4 VFD how would you build a enclosure?
 
It all depends on which NEMA 1 VFD you have. The Chinese NEMA 1 VFD I had works really good by putting a decent filter over the air inlets. No need for an enclosure. Now, if you want an enclosure, pick up an electrical junction box that's large enough.... or, if you're wanting to "cheap out", pick up a plastic box from WalMart or some place that will fit your VFD. I'd want a clear front so I could see the display of the VFD. OR, if it's the removable type display you could mount it on outside of box (sealing the display). Being able to see the display allows you to see the SFPM (or RPM) of the motor.

The enclosure can be as fancy as you wish, or as simple and cheap as you wish.
 
So the deal with the enclosures is this. Any metal dust floating around the VFD is going to be attracted by the magnetic fields of the electronics and current flowing. The metal dust finds it's way to the circuit board and settles into the various components. You can try blowing the dust out periodically (and you should) but most metal dust seems to fuse to the electronics building up until the controller shorts out. I've seen this personally twice. The enclosure needs to filter fine metal dust. Anyway you can figure out how to do that is what you are after. You also need to consider heat dissipation. Most NEMA 4 enclosures are metal and act as their own heat countersink. You will need to figure out a way to get rid of the heat built up in a home made enclosure.
 
I know it's tough to hear, and just to qualify what I'm about to say... I've been at this a LONG time.... in fact before VFDs became commercially available, I was using the old DC motors/controllers, and I have seen time and again people say "I just can't afford a VFD with an enclosure." Truth is, you can't afford not to. The reason is, I have never seen a homemade enclosure that was able to protect the electronics in an open VFD.....and the VFD ends up shorted out (the way Tracy mentioned above), and the individual(s) end up having to buy another. Often time this scenario happens a few times before the individual(s) breaks down and buys what's needed..... a VFD that is built into a NEMA 4 enclosure. Meaning they spend 2-3X the money it would have cost to buy something like a KBAC 24, 27, or 29 VFD in the first place.... that will be trouble free, and last. I try to operate the shop off the principle of "Buy once, cry once". I've learned that if I buy the "right" tool/appliance the first time, I don't have to buy it again. If I try to cut corners, it always comes back to bite me.
 
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I'm with Ed on this. I have a KBAC 27 awesome unit. If I was going to do it again I would buy the KBAC 29. It is only 5 to 10 bucks more and if I ever needed a 3HP motor for my Grinder I wouldn't have to buy a new VFD like I would now.
 
When I started building grinders and using VFDs I looked into using cheaper VFDs and building enclosures. By the time it was all said and done not only was the end result better using the KBAC VFDs it was more economical too after you considered the cost of the products and time involved. My advise, just go ahead and get the good stuff. You can not start with a Chevy and turn it into a Rolls.
 
I have an open frame VFD in my shop that I run my mill and surface grinder on, and I just stuck it in a small wooden cabinet with a couple of holes drilled in the bottom. Years later it's still dust free and going strong, though if it were a little closer to my grinder, I'd probably add some filter material where the "air holes" are.
 
I agree with you Andrew - those Chinese VFD's are one of the best values around for driving a grinder, lathe, disk, etc. Work good and easy to protect from dust - especially for a hobby person who's not running the VFD 8 to 10 hr/day, 5 to 6 days/week.
 
at the office we used plain NEMA 1 VFDs and never had issues even with mass quantities of metal and graphite dust in the air. Locating your VFD is important also, mine is above and behind the grinder table, so it is away from grinder dust. as far as brand to use, I never heard of KB until I came to knife forums. I own or have maintained units by Leeson, AB, Siemens, Square D, Fuji, TECO, and Marathon. these are all industrial grade programmable VFDs, built to run 24/7 for years. spend your money how you want, but the difference in price between TECO and KB is enough to pay for a basic table saw or table top drill press.
 
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