VFD shopping time: Is the KBMA-24D sufficiently enclosed for a grinder? DIY enclosures?

Fitzhugh

Fitzhugh

Joined
Feb 5, 2013
Messages
194
I'm shopping for VFD to start a grinder build.
I only have 110v, can't afford a KBAC-27D, $357 [$375 w/ power switch].
I have decent 1hp 3 phase TEFC motor - room to upgrade to a 1.5 or 2hp motor later would be nice but not critical.

Getting one with an unsealed enclosure cuts the cost way down - but only if I don't fry it.
I'm considering making a DIY enclosure for an IP-20 rated model, or would an IP-50 be OK as-is?
I'll be putting the grinder on a cart so I can use it mostly outside, so remotely mounting the VFD to protect it isn't really an option.

I don't have any experience with VFDs. I don't have a sense how much heat they put out, or know if I'm asking the right questions, etc.


Here's the one I hope will work. I know some people have this VFD - comes as a standard option on Tru Grit disk sanders...

KBMA-24D
6YAfD6y.png

$167
1hp IP-50
Is the IP-50 enclosure enough protection for a grinder? Maybe sanders just put out less dust?
What about just sealing the enclosure with a bit of foam tape or silicone - Would heat become an issue?


I've also been looking at these two...

KBAC-24D
KVu9un4.png

$238, $254 when you add the power switch.
1hp NEMA 4x
The price is pushing it, but it won't fry. Unlike the KBMA series that has AC power switch, this has run/stop switch, with hole for an accessory power switch.


KBDF-27D
KLdvmIZ.png

$220
1.5/2hp IP-20
It's the unprotected, digital interface sibling to the often recommended KBAC-27D.
Would be great if I can keep it from burning up - leaves room for a future motor upgrades.
I'm picturing an outer enclosure with a cutout routed out so the panel exposed, with a foam gasket around it. Again, what about heat? I could mount additional controls, but not sure I gain much for the expense since the front panel looks sealed enough.
What about just adding filters? How effective is that really?


I'm steering clear of the few budget imports that take 110v because I haven't found any positive reports. I'm also put off by sellers claiming different specs, like as much as 4hp on 110v. There are also some other options, like the 1.5hp KBVF-26D for $191. It needs a complete enclosure added and all the controls, would end up being as much as the KBDF-27D. WEG has one 110v model but it is more expensive that the KB near-equivalent.

I'm open to any advice, would really like to hear from anyone who has made their own enclosures. I'm sure it's been discussed but only found page after page of the count's standard reply when searching (mentions all the keywords I thought to try).

Thanks
 
IP50 is listed as "limited dust ingress protection" and "no protection" for water. That means that it's not just bad to spray it with a water hose, but it has no protection against condensation either.

I just plunked down the money myself, after much searching as you're doing. I got the KBAC 27D.
 
Thanks for replying. I know you are right, that the best, safe answer is the KBAC 27D, it's just out of reach. Next safest is the 1hp version of the same KBAC-24D, and though that's pushing it as well I may end up going that route.

I'm glad you brought up water... I've only run my 1x30 dry and wasn't thinking beyond just dust. Condensation isn't much of an issue here but would like to be able to add a mist system at some point. Mounting location might help avoid the worst of it.
 
I built my own enclosure for one of the cheapest unsealed VFD's available. One thing that I noticed was that the instruction manual made clear that the unit must have unrestricted air flow for the built in cooling fan. This leads to a few problems:

The purpose of the enclosure is to protect the unit from conductive metal dust, insulating wood dust, and possibly some water mist from dipping the blade. How do you make an enclosure that does all that while still giving unrestricted air flow?

Another consideration is how do you adjust the speed, read the display, or control the unit if it is in an enclosure?

Sounds like you are already thinking about these problems. My solution was a large industrial utility box, a quality fan, filters for the airflow, wiring, a switch, fuse holders, indicator lamps, and a remotely mounted control head.

I still blew a fuse one day when some ultra fine dust made it inside. I reworked the filters and believe that I solved the problem. Luckily the drive didn't fry.

When I carefully cleaned out the VFD I found that the circuit boards in mine have a nice layer of coating all over the traces and components. That gives some extra protection.

So, I think you can build an enclosure that will work, but unless you can scrounge up everything, it will end up costing more then a sealed unit and will probably still have a shorter lifespan.

Good luck!

Ben
 
People on a budget have used a good size plastic storage bin to house an open cased VFD. It should be much larger than the VFD and have a clear plastic lid so you can see inside. Something 18X10X6 is good. Mount the VFD on a piece of aluminum plate that fits in the box bottom. This helps as a heat sink. Screw the VFD/plate and box on the mounting post or wall. Drill a bunch of 1/4" holes in the top and bottom of the box. Tape some filer material from an AC filter over each end. Many folks put a cheap cooling fan from an old computer or ebay in the bottom of the box blowing upward across the VFD ( and out the top). Run all wires through a larger hole in the box bottom or side, fitted with a cable clamp.
Run the speed pot and the ON-OFF switch out on "remote" wires to a small metal box that you mount near the grinder.
 
KBAC 24D is all you need...Run/Stop switch is all you need to operate. No additional housing required. The On/Off power switch can be added later if you feel you need it or want it. The Down Side is you will always be limited to 1 hp motors. I'm a Buy Once Cry Once guy so if I have to cut out ONE Bacon Cheese Burger and Beer a week for a month to save an extra $100.00 for an upgrade I'll do it...I won't like it, but I'm looking at the Big Picture:cool:
 
Just a couple notes from my experience: I have the Dayton branded version of the KBMA vfd. I use it on my disc grinder, and I've had zero issues so far. You can still use cable glands and dust proof switch covers if you like. IIRC, I just put some romex clamps on mine and pumped a little bit of silicone caulk into the ends of them, as well as a piece of gorilla tape or caulk around any other hole or seam I thought might be an issue. I went with that particular VFD because I found it brand new for like $120 on eBay and didn't want to pass up on the deal.

I also have a couple Chinese VFDs. One is in a dust proof metal enclosure that I purchased from FactoryMation.com. They have pretty decent prices. My other has been in a simple wooden cabinet for the last few years. I have a couple of holes drilled in the bottom for air flow (probably not necessary), and I've had zero issues with that one.

Some guys will wrap some filter material around the open VFDs for an additional measure of protection as well.
 
BTW, if you're building a 3 to 4 wheel grinder, I'd recommend sticking with at least 1.5 to 2hp. You can get by with 1hp if it's direct drive, but you'll likely outgrow it quickly and wish you had more.
 
I really wouldn't worry too much. Get a cheap unenclosed unit, place it in any kind of rudimentary enclosure, put it somewhere where dust isn't getting thrown directly at it, and call it a day. Mine is in a 1/4" plywood box that is about twice the base area of the VFD and has a hinged door that I can open and adjust the speed and then close up. There is a switch on the outside of the box to turn it all on with, since my VFD is so cheap it doesn't actually have its own on/off capability. It sits about a foot and a half from the grinder on the table.
 
I appreciate all the help. It was very much the info and opinions I was hoping for. Stacy, thanks for the detailed description.

I decided to ponder as I checked the free motor with a multimeter for the first time, just to be sure, and thanks to not being very systematic (or smart) I spent a long 20 minutes thinking the motor was fried.

Made me realize I was going to come up with the cash to proceed one way or another, so screw it, I'll break down and get the KBAC 27D. It does mean I'll have to wait to proceed with the overall build, but I won't burn it up or kick myself later.

Drew, thanks for the comment on HP. to make it work I was trying to by happy with 1hp.

Ken, that would apply to the KBVF-27D. 110 option with a very similar case, for others seeing this.
I took your plans and the ones shared by bjansen as a starting point, will post them in a new thread for critique before building. Thanks for inspiring me to try this.


I appreciate the patience covering stuff that is close to other questions already asked.


Rhinoknives1 said:
What kind of knives are you making with a 1 x 30”? Length ,Width Etc? Small pen knives?
Click to expand...

I've only used the 1x30 for profiling after bandsawing, not bevels, and really most of the profiling I've done with files as well. The few knives I've made have all been hand filed, including most of the profiling really. They've been small fixed blades made from 1084 left over from woodworking tools I made, and a few 1080+. The one in my profile pic is the first one I felt proud of - though it has its warts.
I've had to move away from my main hobby of woodworking as I get more allergic to the dust. (motor for grinder was a freeby when I bought a 5hp for a diy dust cyclone). I'll go nuts without projects... I realized I had more fun making knives from left overs than I had had doing woodworking in a long time.

Anyhow, I really want to try my hand at kitchen knives, and honestly, making the grinder itself will be as much fun.
 
I overlooked that only 110VAC was available. If you can get 220VAC, it will significantly upgrade your options. 110VAC used to limit you to 1hp, unless you go with a KBAC27, which will run on 110VAC and get you up to 1.5hp.

I just found this one on amazon:
https://amzn.to/2NCciyq

Apparently it will take a 110V input, but I'm not sure about the 2hp output, as that would draw about 25 amps, IIRC (don't quote me on that). It's probably gonna yield about 1.5hp from 110, if I had to guess.
 
Thanks for posting that. I saw that and a couple other budget Chinese imports that accept 110, but unlike the more common 220 only ones there are very few reports of them working out well. Or rather, I saw reviews that said they're good if you get a good one but a high failure rate out of the box.
I also asked the seller about the statement "only for cnc spindles" in the listing (or same from different seller). They said it would not work on a 1hp 3ph motor, but not why. I got scared off, not knowing if they were confused or if there is something truly different, since those spindles run so damn fast.

It's odd, there same model comes in up to 4hp on 110v. Don't know the amps needed... 56? (4x14, don't know if it actually scales longer that). Who has circuits for that on 110?

From the KB docs, on 110v 1hp draws 16amps max, needs a 20 amp breaker, while 1.5hp draws 22ampa max, needs a 25 amp breaker. From what I've read here you can get away with less because we aren't really taxing the motors as much as many uses - pretty sure I've seen people say 15amp circuit can be enough for 1.5hp on a grinder (but as you say, don't quote me on that).

There's also a sub $100 unit, but it had no reviews at all.


It's funny, I think this same path led black fox grinders to offer the KBVF-26 as the optional VFD. It's only $191, over 1hp (1.5 on 110 or 220) and costs less because it's not enclosed and has no controls included. With their grinder's integrated panel it almost makes sense, but for just a little more than they charge for it you could have a sealed 27D
 
If your building a 2 x 72, a 120V 1 1/2 hp with the KB variable has suited me fine for over 20 years making 3” to 12” knives, Chef, Camp & skinners. I also have a 1hp with variable that I’ve used for up to 7” culinary! The trick is to buy a name brand quality belt, and after I’ve used about 50-60% of it. It goes to the profiling pile! I also started with Files! :thumbsup: Great way to learn about shaping steel! Welcome to the obsession:D
 
Rhinoknives, thank you for the encouragement.
I plan to follow your advice about belts. As cheap as I am, I've seen others similarly say cheap belts are a false economy.

Thanks for all the help.



And purely for the sake of others who are searching with similar questions and find this, here is the other 110 vfd I found on Amazon...
https://www.amazon.com/gp/aw/d/B079R8Y7KX
Only $94!!
And it ouputs 110v 3 phase! Woohoo!
wait what?

Note what's listed in the description:
Input Voltage: AC 110V 15% [... 15% of what?]
Output Voltage: AC 110V
Input Current: 14 A
Output Current: 20 A
Input phase: 3 phase
Output phase: 3 phase

Maybe it's correctly configured for use on North Sentinal Island.
 
Fitzhugh said:
Rhinoknives, thank you for the encouragement.
I plan to follow your advice about belts. As cheap as I am, I've seen others similarly say cheap belts are a false economy.

Thanks for all the help.



And purely for the sake of others who are searching with similar questions and find this, here is the other 110 vfd I found on Amazon...
https://www.amazon.com/gp/aw/d/B079R8Y7KX
Only $94!!
And it ouputs 110v 3 phase! Woohoo!
wait what?

Note what's listed in the description:
Input Voltage: AC 110V 15% [... 15% of what?]
Output Voltage: AC 110V
Input Current: 14 A
Output Current: 20 A
Input phase: 3 phase
Output phase: 3 phase

Maybe it's correctly configured for use on North Sentinal Island.
Click to expand...
Yes! Cheap pretty much anything in knife making or life is a false economy! My motto is only cry once! Buy the best equipment you can afford. I use VSM Ceramic belts and get them from www.trugrit.com I grind after HT and I only ask 1-2 knives of each belt! They work great! Try them.
 
Bookmarked, thanks!
At this time I'm pointedly NOT looking at the cost of belts ;) Call it willful denial in the service of the project.

I've added up the cost of all the material, hardware, wiring, vfd, wheels and a few taps and transfer punches l'll need and it's less than I originally feared but more than I hoped.

$850 for the complete aluminum 3 slot grinder with platten and tool rest, good wheels, KBAC-27D, wiring, and free motor.

It would come out to just around $700 if you had to buy the motor but went with cheap wheels, a budget 220v vfd. (that's with a 1½hp 3600 rpm iron horse).
 
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