Grinder motor died. In a quandary which direction to go, VFD or?

Sean Jones

Sean Jones

Well-Known Member
Earlier this week the 1 1/2 HP motor on my grinder died. I thought at first a bearing had gone out, so I took it partially apart and the bearings looked OK. So I took the motor down to a local repair shop and they found a short in the winding's. They quoted me $400.00 to rewind the motor! Needless to say I'm not doing that.

So here's the quandary. This seems like a good time to update my shop to 220 volt so I can get a bigger motor and run a VFD. However there's the cost and the time. The cost is a big concern. I'm retired and have a little bit of money for such a project, but it seems like such projects tend to take on a life of their own and go over budget.

I'd have to do the shop wiring myself, which I can do. But there's only one space left on my panel for 220. So it would seem logical (perhaps) to put in a subpanel, which I'm not up to doing, so there would be the cost of having someone do that for me.

On the other hand, I can get a 1 1/2 HP Leeson motor from Amazon for about $300.00, call it good for now and upgrade later when money may not be quite so tight.

Additionally there's the time. I don't want to be down for two-three weeks getting new wiring etc done and not producing anything at all.

So...subpanel and 220, VFD and downtime?...or 1 1/2 HP now, get up and running and look at the VFD option later? Or some combination I haven't thought of?

I should mention I haven't sold any knives. In fact I've made very few. I seem to spend more time messing with my home built grinder than getting knives done.


Thanks for any input
 
Do you think you are pushing the limit of the 1.5hp motor? My grinders run on 2hp and I've never really felt like I needed to upgrade. I think part of it depends on the style of grinding of the individual.

Also, you can get a 3ph 1.5hp motor and a vfd and run it on 110v. I know you can with the kbac 27d anyway... not sure about chinesium models. And if you got the kbac 27d, you could change a jumper and be set up for 2hp 3ph motor if you ever decided to upgrade (with 220). Just another option to consider. And 3 phase motors are cheaper than single phase.
 
C. Killgore said:
Do you think you are pushing the limit of the 1.5hp motor? My grinders run on 2hp and I've never really felt like I needed to upgrade. I think part of it depends on the style of grinding of the individual.

Also, you can get a 3ph 1.5hp motor and a vfd and run it on 110v. I know you can with the kbac 27d anyway... not sure about chinesium models. And if you got the kbac 27d, you could change a jumper and be set up for 2hp 3ph motor if you ever decided to upgrade (with 220). Just another option to consider.
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No...I've never felt like I've pushed the limit of the motor at all. For the most part I grind fairly slowly and lightly .

Hmm I didn't know you could do that with the KBAC...the jumper that is. That's a good idea. I think I'll look at a 3ph 1.5hp motor and the VFD. That sounds much simpler.
 
If you are happy with a 1/12hp motor I would pick up a iron horse motor and hook it up to a KBEC 27d. There’s a jumper that will allow you to run on 110v. That being said it sounds like you have a prime opportunity to switch to 220 personly I always want more them 11/2hp so I would get at least a 2 hp motor hook it up to a KBEC VFD and Bobs your uncle!
 
It’s what I would’ve gotten if I hadn’t found a deal on the Baldor motor I have now. Inexpensive and I’ve heard nothing but good things about them.
 
Well, I have a 2hp single phase with pulleys and dearly wish I had gone with the vfd system.
Could you maybe take your time and do the subpanel first, get everything done except the final connections and then when you are ready, take everything down for the final bit of hookup and save some time on the downtime for your grinder and spread your costs over a longer period of time?

Don't know if that makes sense or not, hope it works out for you.
 
When I built my grinder with a VFD and 3 phase motor I could not believe how much quieter, smoother and how much more power I had. There is vibration, noise and transmission losses when you use the step pullies.
Send me an e-mail and I can help you with your VFD, motor and wiring kit with instructions for doing the wiring and setting up the VFD. We can avoid your need to rewire your shop.
Let me know if I can help you.
Wayne
 
VFD. There is no question.

If you need to work in a budget, a 2HP Ironhorse motor is how to do it.

Having a VFD is a game changer. You can wire a pigtail with a plug to the output of the VFD and use that same VFD to run other tools by plugging in the tool you want at that time. You may not have other tools now, but you will. Once you have a VFD, all you need is another cheap Ironhorse motor and an $80 disc and you now have a variable speed disc grinder, not to mention a spare motor sitting there should you need it.
 
Just wanted to point out on last nights new Forged in Fire at one of the guys home shop he had a unsealed VFD that blew out mid competition. He had to go out and buy a single phase motor to finish. Granted it didn’t look like he had filters over it but still would you really want to risk it?

I am in no way trying to start a forged in fire debate just pointing out why I would go with the sealed VFD.
 
Wayne Coe said:
When I built my grinder with a VFD and 3 phase motor I could not believe how much quieter, smoother and how much more power I had. There is vibration, noise and transmission losses when you use the step pullies.
Send me an e-mail and I can help you with your VFD, motor and wiring kit with instructions for doing the wiring and setting up the VFD. We can avoid your need to rewire your shop.
Let me know if I can help you.
Wayne
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Thanks Wayne. I'm going to think all of this over today and may contact you. I'll let you know.
 
Here's the link to several different 3 ph IronHorse motors: https://goo.gl/GcqUPa The 1.5 hp is $147 or $181 shipped, depending on 1800 or 3600 rpm choice. "IF" you decide to get 220 vac in shop and run a $62 Chinese VFD until it goes bad, do remember to put filters over air inlet or VFD in box. Most likely it will last several years that way, or the NEMA 1 VFD drives I've got have.

I'll have to check out that Forged in Fire episode last night. I usually watch the recorded version so I can fast forward thru commercials.

Good luck - oh, and no contest, VFD only for a 2X72 grinder. I used a 3 pulley setup for a couple of years thinking that was all that was needed, then went to VFD - boy, you'll never regret the extra cost.
 
I'm convinced that the KBAC VFD is the way to go for a VFD. I'm still mulling over a motor, but most likely will get an Iron Horse. I figure if I get a 1 1/2 HP motor now and upgrade to 220 later I can use the 1 1/2 for a disc grinder, which I've been wanting.
 
Sean Jones said:
I'm convinced that the KBAC VFD is the way to go for a VFD. I'm still mulling over a motor, but most likely will get an Iron Horse. I figure if I get a 1 1/2 HP motor now and upgrade to 220 later I can use the 1 1/2 for a disc grinder, which I've been wanting.
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maybe i’m reading this wrong- but it seems that you’re thinking that upgrading to 220V later will change which motor you need.

110v into the VFD will give you 220V 3 phase on the output. You will lose about 1/2 HP (effectively) but that is irrelevant to the motor you pick.

For example, if you go with a 1-1/2 HP 3-phase motor, you need the 220V motor. It will be ever so slightly weaker if the VFD is running on 110V input. If you’re worried about that power loss go with a 2HP motor and a 2HP VFD.

A VFD’s HP does not have to match the motor. It just has to be at least equal, but it can be as large as you want. A VFD’s HP rating is its maximum capacity.
 
John Wilson said:
maybe i’m reading this wrong- but it seems that you’re thinking that upgrading to 220V later will change which motor you need.

110v into the VFD will give you 220V 3 phase on the output. You will lose about 1/2 HP (effectively) but that is irrelevant to the motor you pick.

For example, if you go with a 1-1/2 HP 3-phase motor, you need the 220V motor. It will be ever so slightly weaker if the VFD is running on 110V input. If you’re worried about that power loss go with a 2HP motor and a 2HP VFD.

A VFD’s HP does not have to match the motor. It just has to be at least equal, but it can be as large as you want. A VFD’s HP rating is its maximum capacity.
Click to expand...
The motor I bought is a this one. The VFD I bought is this one. I hope I got this right. If not I'll send the VFD back and get a different one.

I'm thinking it could be beneficial to have a 2 HP VFD coupled to the 1 1/2 HP motor. I understood that part correctly (I think). But I see what you are saying. If I go to 220 in the future I would need to upgrade the VFD as well as the motor? As it is I think this will suit my needs for some time.

I'm not too concerned about the power loss. I didn't bog the old motor down at all, even when I was grinding hard.
 
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