VFD dust proofing

Ropata

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Anyone seen a good designs for enclosures and/or filtering? Will be starting a belt grinder build soon and I suspect the dust will be prolific.
 
On my surface grinder I used an enclosure with a fan to blow air out and a filter to suck air in. The fan runs when the spindle runs.
 
I have found that Ammo cans are the most affordable VFD enclosures. I use the Fat50 caliber size can which is a little bigger than the more common 50 caliber size. I have used them on 3 different machines. I drill a couple roughly 3/4" holes in the bottom for intake air and a couple holes near the top on the sides for exit air. Then I cut 4 pieces of scotch brite pad and velcro them on the inside of the can to cover the holes. They filter the air so the can doesn't fill with saw dust or allow metal chips to enter from my metalworking machines.

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You will see many grinder and belt sander systems that often use a VFD which is rated for NEMA 4X / IP 65 die-cast aluminum washdown/watertight enclosures for indoor or outdoor use, so something like the KB Electronics KBAC and KBDA, some of the Lenze SMV models, Yaskawa V1000-4X, etc. Most of the grinder systems I see use the KB Electronis KBAC, so you save the cost of a bulky enclosure and fan/filter system. http://www.2x72beltgrinder.com/speed-controller-kbac--ac-tech.html

There are also VFDs that are designed to be mounted to a metal surface/plate in a sealed enclosure, they use no VFD/enclosure fan, the heat is dissipated passively where the enclosure or mounting surface is the heat sink. Last but not least, many if not most VFDs can be mounted in a sealed NEMA 4X enclosure of suitable size without any external fan/cooling system, the VFD fan operates only internal to the enclosure. In these cases I recommend a steel enclosure, with the VFD mounted to a back plate. Using a metal enclosure like a 14x12x8 for up to 3Hp VFDs and maybe a heavy gauge steel or aluminum back plate would be fine. My mill VFD operates this way.

There are some electronic enclosures that use HEPA filtration, but these can be very expensive. What I have often seen is to use something like a lawnmower air intake filter or other small type of filter on the air intake system like compressors, vacuums, etc. These often have a outer foam filter with a pleated interior filter. You could build a simple enclosure to hold the filter onto the enclosure. I would put the air intake on the bottom of the enclosure under the VFD, so air is drawn into the enclosure by a separate electric fan. The interior of the enclosure is under slightly positive pressure, and have an air exhaust on the side near the top of the cabinet, usually with a screen and/or louvered (I often use a 4" soffit vent).
 
This was designed by Mark (mksj) for the 1440 lathe. It pulls air through a filtered opening and runs when powered up. For you application I would try to add some kind of vacuum recovery if you belt is enclosed.
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Belt sanders are valuable to any shop but messy as hell. You also might consider protecting other equipment in close proximity to the sander if working in tight quarters.
 
Grit is death to machine tools. Keep the gritty tools far away from lathes, mills, etc. If you plan to use a passive sealed enclosure for the VFD, check the manual for the manufacturer's recommendations. Passive enclosures need to be quite a bit bigger than ones with through flow air or recirculating air. Mark's idea of using a heat dissipating back plate for the VFD is a good one, just make sure the plate can effectively dissipate the heat into the room. Trapping it against an insulated wall, for instance, would not help much.
 
In addition to the filtering recommendations already made, I would hint that you do not *have* to mount your VFD on the tool. I have my VFD enclosure mounted up on the wall away from the machine. If you mounted yours high up and away, you'd have less dust to contend with.
 
Good points everyone, thanks.

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Forced air via fan, filter the incoming air creating a higher pressure inside the enclosure. Mostly zero ingress.
 
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Forced air via fan, filter the incoming air creating a higher pressure inside the enclosure. Mostly zero ingress.
Yes, this looks to be the cheapest and I have a big pc fan lying around.

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