Recommendation? Need for speed

3fifty7

3fifty7

Joined
Dec 24, 2016
Messages
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I have a home built 2x72 grinder that I’ve been using for nearly 3 years. It’s a 2hp- single ph - 220v - TEFC that’s running about 1800 SFPM.
Being 220v single ph, is my best option for more speed a step pulley system?
If so any recommendations or things to avoid ?
 
You can just get a bigger drive pulley to get more speed. If you want variable then you can do the step pulley. Mine is a 4 pulley setup so it a good variety of speeds.
 
3fifty7 said:
I have a home built 2x72 grinder that I’ve been using for nearly 3 years. It’s a 2hp- single ph - 220v - TEFC that’s running about 1800 SFPM.
Being 220v single ph, is my best option for more speed a step pulley system?
If so any recommendations or things to avoid ?
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1800 SFPM is only 9 m/s ? What RPM have your motor and what Dia. is drive wheel ?
 
I figured it when I built it but I’m not around it right now. I’m sure it was either 1725 or 1775 rpm with a 4” drive so my sfpm should be nearly equal to my rpm.
 
If you only want a single speed grinder then a larger drive pulley works just fine. You will have to go with an 8" drive wheel to get 3700 SFPM belt speed, and that's not much. You didn't mention your drive wheel size. Since the grinder seems to be single speed, it must be direct drive? edit: you posted drive wheel size while I was typing this. You're right, with 4" drive wheel belt speed is about same as drive wheel RPM, which is motor rpm with direct drive.

Take a careful look at the cost of adding a pulley system for 3 or 4 different speeds. Then look at cost of a 3 ph motor $167 shipped for new 2hp, 3600rpm. then $60 to $80 for a good NEMA 1 VFD to put filters over air inlets. "IF" money is no object then go with the NEMA 4x KBAC VFDs.
 
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I’m mostly wondering if there is much difference in quality of step pulleys. Right now it tracks great and runs very smooth.
Should I worry about the pulleys being balanced, just looking on the line at pulleys priced from $15-$30?


If I was starting over I’d definitely go the VFD route, but when I was starting out I was just wondering with what I had laying around. Perhaps one day I’ll build a disc sander and rearrange my whole setup.
 
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Since you are considering upgrading NOW is the time to consider a VFD. Over the years I've read many threads of why people waited so long to upgrade to Variable Speed they all say "Why did I wait so long?". Step pulley system is a good starting system BUT nothing like Variable Speed Control with the twist of a Knob. If you're going to do it Do it Once you won't regret being able to go from 0 to Wide F'n Open in the the blink of an eye. It does require a 3 phase motor swap out but they are less expensive than 220v single phase motors. This is a true NO Regret Upgrade!!!:thumbsup::thumbsup::thumbsup:
 
Busto said:
Since you are considering upgrading NOW is the time to consider a VFD. Over the years I've read many threads of why people waited so long to upgrade to Variable Speed they all say "Why did I wait so long?". Step pulley system is a good starting system BUT nothing like Variable Speed Control with the twist of a Knob. If you're going to do it Do it Once you won't regret being able to go from 0 to Wide F'n Open in the the blink of an eye. It does require a 3 phase motor swap out but they are less expensive than 220v single phase motors. This is a true NO Regret Upgrade!!!:thumbsup::thumbsup::thumbsup:
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All day, every day. Even on other tools, I've NEVER regretted forking out a little more for variable speed. Belt grinders, bench grinders, wood & metal lathe's, sanders, routers, drills, band saws, etc...
 
Damn and I was all set to not go the VFD route just yet. I just don’t make enough knives and use it enough to justify the cost now.
 
Your GRINDER is the number 1 tool in your Knife Making Arsenal...Do you change belt speeds on a Drill Press by swapping Belts on a pulley system...it's the same pain in the keester to do on a grinder...believe me the ability to turn down the speed with a knob to get a better belt finish is worth every penny...Ask anyone with a VFD if they would go back...:eek::eek::eek: The Benefits of Variable Speed outweigh the cost over your pulley system you won't believe how much better control you have grinding...If they were just all Sparkle and Glitter for the rich you would not see them on the Majority of Grinders being produced today!!!
 
3fifty7 said:
I have a home built 2x72 grinder that I’ve been using for nearly 3 years. It’s a 2hp- single ph - 220v - TEFC that’s running about 1800 SFPM.
Being 220v single ph, is my best option for more speed a step pulley system?
If so any recommendations or things to avoid ?
Click to expand...

Yes, avoid the step pulleys

VFD direct drive is the way to go.

If you add up the price of the pulleys, shafts, bearings and work to line it all up; you're already more than half paid for a VFD
Get a NEW KBAC 27d and save your money on a used motor, stay away from the ebay chinese vfd's


I find I've pissed more money away on beer, coffee, fast food, vehicles and other things that don't stick around compared to the few quality items that I really cherish and value.
 
3fifty7 said:
Damn and I was all set to not go the VFD route just yet. I just don’t make enough knives and use it enough to justify the cost now.
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If you make 1 knife every 10 years, you make enough knives to justify a VFD. ;)

Keep an eye out on craigslist or local motor shops. You should be able to find a used 3 phase motor for less than $100. I've seen the as low as $50. Or you can get a brand new IronHorse from AutomationDirect for less than $200.

As for VFDs, the KBAC-27d is the standard for belt grinders, but if you don't have $350ish to spend, you can start off with a Chinese VFD from eBay for around $100 (I've seen them as low as $70). Just make sure you get one with a potentiometer (knob for speed adjustment) as it's about 100x more convenient.

Long story short, you can get a VFD and motor for anywhere from $120 to about $600 (for top of the line).

One additional caveat for the cheaper VFDs: They normally need 220VAC input, and they need dust protection as they're open frame.
 
The Chinese VFDs seem to be very reliable, and are easy to setup. They also have an advantage over the KBAC drives in that the desired amount of over speed can be selected on Chinese, while the KBAC only has a choice of doubling the speed.

A speed pot is handy, but are easy to mount. I usually mount a ON/OFF switch in a remote box along with the speed pot.
Drew Riley said:
.....they need dust protection as they're open frame.
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That's an easy fix with filters added over the air inlets.
 
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Ken, I think the link is to a 110v in, 110v out unit: not a 110v in, 220v out unit like some of the KBACs. I suspect it’s about as useful as a chocolate teapot.
 
timgunn1962 said:
Ken, I think the link is to a 110v in, 110v out unit: not a 110v in, 220v out unit like some of the KBACs. I suspect it’s about as useful as a chocolate teapot.
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Tim, glad you caught that and you're right. I didn't read far enough down. It really seems a 120vac input with 220vac 3 ph output would be LOTS more useful than 120vac 3 ph output. As you said, "chocolate teapot".
 
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3fifty7 said:
I’m mostly wondering if there is much difference in quality of step pulleys. Right now it tracks great and runs very smooth.
Should I worry about the pulleys being balanced, just looking on the line at pulleys priced from $15-$30?


If I was starting over I’d definitely go the VFD route, but when I was starting out I was just wondering with what I had laying around. Perhaps one day I’ll build a disc sander and rearrange my whole setup.
Click to expand...
Yes there is a diff in the amount of vibration. Smooth = more knives in less time with less fatigue ..
Jesse Latham said:
Everyone who has variable speed tools will tell you the same thing. Save your pennies for a while if you have to.
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This^^^^
3fifty7 said:
Damn and I was all set to not go the VFD route just yet. I just don’t make enough knives and use it enough to justify the cost now.
Click to expand...
You will be able to make more knives and use less of your finer belts with A VFD. The finer the belt. The slower you want to run..
 
Ken H> said:
The Chinese VFDs seem to be very reliable, and are easy to setup. They also have an advantage over the KBAC drives in that the desired amount of over speed can be selected on Chinese, while the KBAC only has a choice of doubling the speed.
Click to expand...
If I recall correctly the KBAC has a jumper for 2x and an adjustable max frequency from 70%-120% or so. This should give you some flexibility setting the over speed.
 
Hubert, you might be right on the KBAC drive. I've always heard about the "2x jumper" without hearing anything about the adjustable freq setting. I never setup a KBAC and have not really read the manual so I will take your word for it. There goes one of my issues with the KBAC drives. They are good drives, but do cost a pretty penny.
 
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