Grinder VFD Location?

T

The Mighty Ginsu

Joined
Aug 11, 2016
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251
Now that I've figured out why my motor wouldn't run right, I am getting my grinding cart fixed up for use. Photo attached.

I am wondering if anyone can shed a little light on the issue of VFD placement.

Obviously, this VFD is not enclosed. I would really prefer not to buy a printer-sized box that will cover the remaining space on the platform. I've noticed that not everyone uses an enclosure. I saw a photo here of an Esteem grinder with a VFD mounted on a stalk about a foot high, presumably to get it above the flying crap. Is this an acceptable solution, or would it shortly result in a fried VFD and broken dreams?

If a stalk won't work, I was thinking of simply putting a couple of pieces of acrylic (vertically) between the VFD and grinder.

 
Metal dust from a grinder gets everywhere. I have my VFD on a "stalk" as you call it, but it's a nema4 enclosure which is dust and water proof. It also has an aluminum heat sink to dissipate heat from being enclosed. If you don't enclose and cool that VFD, it's more than likely going to let it's magic smoke out.
 
Mount the VFD on a wall or even in the next room. Run the wires from it to the motor and to a remote On/Off switch and a speed pot that are at/on the grinder..

Alternately, put the VFD in a box to keep the dust out. The VFD would be fine mounted inside a plastic storage box for shoes ( about 6X6X12). Making vent holes with filters covering them, and providing air flow from a small computer fan will keep the VFD from burning up.
 
Mount a 2x4 vertical by your motor and screw in a clear tote with a lid. Cut out a whole for the VFD bada bing. It may seem ghetto but from what I read it works good
 
I made a similar mount to the KMG for mine, and mounted them to the left of the grinders. I like it within arms length. Dust... cannot help ya there.
 
So it will be a project, no matter what.

I used to have it on the wall when I was using it to run my mill, but that is not an option with the grinder. I suppose I will have to go with the enormous unvented can option. I really don't want to construct a metal box with filters and fans that have a separate AC supply. I guess I can put it in the lower tray of the cart, which I had hoped to use for storing other things.
 
The really annoying thing is that the VFD manufacturers make their devices about one inch too wide to fit in 99% of the available cabinets. Zoro Tool has a perfect cabinet for about $27, delivered, but it's only 4 5/16" wide, and my narrowest VFD is 4 3/8".
 
There are large switching currents in the power section of a VFD. These produce much of the heat that needs to be got away by ventilating. The same high switching currents also produce magnetic fields which will attract fine steel dust to the power switching components. This double whammy means that it's not so much a question of whether an unsealed drive in the vicinity of a grinder will fail, but a question of when.

With a lathe or milling machine, you'll generally get away with mounting a drive on the wall behind it, or somewhere else that the relatively big bits of metallic dust will not reach. With a grinder producing lots of fine dust, it's much more difficult.

Definitive answers are not really possible, especially without knowing exactly how everything else in your shop is sat up. For example a guy with a state-of-the-art extraction system might have no problems at all because all his dust gets captured.

If you are a fastidious individual (many knifemakers seem to be), have a location that never needs brushing, vacuuming, etc, and which will never transfer anything to a powerful magnet when you sweep the area with one, that "might" be an acceptable location for the drive.

Otherwise, seal it, move it to a clean location or build the cost of regular drive replacements into your knifemaking budget.
 
I've learned a few things, so I will share.

If you want to find a VFD box without going insane, do not search for "project box" or "cabinet." Search for "NEMA enclosure."

I found something that looks okay, for an amount of money I can stomach. It's a hinged BUD Industries 10x10x6 box.
 
I've been pondering this as well since I'm putting together a OBM and vfd/motor. I think the only way for me is to build an enclosure with a fan and filter. I'll post some photos of what I come up with.


Sent from my iPhone using Tapatalk
 
There is a good case to be made for shopping for a VFD in Nema 4 enclosure. Rather than building a case and wiring fans and filters it would be much better to buy a VFD like a KBAC drive that you can mount on the left side of your grinder and dial the speed you want instantly. I know you already have a VFD but if you are a serious knife maker you will probably want to upgrade to a Nema4 cased VFD that you can quickly make speed adjustments to with every belt change and have more control of your grinding. Just my opinion. Larry

zYmxqSGm.jpg
 
The Mighty Ginsu said:
Now that I've figured out why my motor wouldn't run right, I am getting my grinding cart fixed up for use. Photo attached.

I am wondering if anyone can shed a little light on the issue of VFD placement.

Obviously, this VFD is not enclosed. I would really prefer not to buy a printer-sized box that will cover the remaining space on the platform. I've noticed that not everyone uses an enclosure. I saw a photo here of an Esteem grinder with a VFD mounted on a stalk about a foot high, presumably to get it above the flying crap. Is this an acceptable solution, or would it shortly result in a fried VFD and broken dreams?

If a stalk won't work, I was thinking of simply putting a couple of pieces of acrylic (vertically) between the VFD and grinder.

Click to expand...

move the VFD to the other side of the motor mounted on a 'stalk', piece of flat stock or angle iron so the control panel faces you when you are standing next to grinder. find a piece of 1/4" aluminum the size of your VFD back(the heat sink), drill holes for VFD, mount on 'stalk', then mount the VFD. if worried about dust, get some loose furnace filter material and fashion a cover for 3 sides. if i remember, your fan blows out, so leave that area uncovered. just moving the VFD to the other side of the motor and above it will get it out of most of the dust.
scott
 
Scott has a very good answer - move VFD to other side of grinder, with VFD bottom mounted a foot or so above table. Cut sections from a fabric type AC filter to cover the air inlets to VFD. I've been running a NEMA 1 Chinese VFD for a couple of yrs now mounted that way. That is with "hobby" use, NOT a full time knifemaker type work. If used for full time knifemaking, then bite the bullet and buy a NEMA 4 rated VFD.

I decided on the Chinese NEMA 1 VFD because it's cheap - just a tad over $100 shipped for a 3hp rated unit. I can buy 3 or 4 of them for cost of one NEMA 4 27D 2hp that is close to $400!

Ken H>
 
Ghostman3 said:
I've been pondering this as well since I'm putting together a OBM and vfd/motor. I think the only way for me is to build an enclosure with a fan and filter. I'll post some photos of what I come up with.


Sent from my iPhone using Tapatalk
Click to expand...

No

The easiest way is to buy a VFD with a NEMA 4, or IP65 rating enclosure

Then just use it.
 
One more reason a commercial Nema 4 unit is the best choice for most people is they come with tech support and a warranty.

I regularly hear people say they have a KBAC Nema 4 drive that has run daily for 10 years ... but can't recall anyone saying that about a $100 Chinese unit.
 
Stacy E. Apelt - Bladesmith said:
One more reason a commercial Nema 4 unit is the best choice for most people is they come with tech support and a warranty.

I regularly hear people say they have a KBAC Nema 4 drive that has run daily for 10 years ... but can't recall anyone saying that about a $100 Chinese unit.
Click to expand...

Wow, I resent that! It's a $250 Chinese unit!!! :grumpy:

In reality, I am planning to use a Hitachi, but it's not NEMA 4 either. The nice thing about it is that the control pot and LED panel detach and can be mounted by the grinder. I believe that with the TECO, I would have to buy a separate pot and display.

When I got my VFD's, I was thinking about machine tools, not abrasives, and I had no idea enclosed VFD's were available.

I'm sure other people are in the same boat, so for their benefit, I will give info on the box I found. It's a BUD Industries JBH-4961-KO. The volume is about 600 cubic inches.

I don't like paying almost $40 for a box that surely cost five dollars to stamp out, but there it is.
 
if you keep them dry, VFDs will run for a long time. at the office, we had a 3hp Allen Bradley VFD that after 3 years of 24/7 operation, started to show overcurrent faults. took it out, blew out about 4 ounces of graphite dust, reinstall, and it ran for another 18 months. yes with the TECO you would need seperate pot, about $10 worth of stuff at Radio Shack. I bought my TECO from Dealerselectric.com, had no issue getting tech support.
scott
 
Fwiw, we used large ammunition can as an electrical enclosure.
It was expedient thing I had hanging around & worked well.
Ventilation via 120mm fans Filtering on the intake supplemented via big alnico magnet.
Its stunning the magnetic crap prevented reaching the filter.
( this was well before rare earth magnets were common)
 
I actually have a can with a fan in it. I rigged it up to pump air into an old propane tank I converted into a fire box for a smoker. I cut a big hole in it and installed a PC fan with an old wall wart to power it.

I can't give up my smoker, though! I have my priorities.
 
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