How much table saw do I need... or want?

[Tim Einwalter]

Well, this is turning into a total ClusterMess. The table saw that I bought came with a 3ph 3ph motor. Initially I thought I'd just hang a VFD on it. When I went to order the VFD I discovered, for my prefered brand, that units 3hp and over had a 3 phase input. I don't have 3 phase power. Searching other brands, the only one 3ph option was a Chinese VFD. That won't happen. Not wanting to do a rotary converter I decided to replace the motor. I found a nice TEFC 7.5hp motor on craigslist and bought it. Unfortunately, the motor isn't close to fitting. The housing would be too long for the end cover to fit and the capacitor housing is nowhere close to fitting. Damn.

I then went back to CL and bought really nice Baldor 5hp motor that was new in the crate. By now I was wise to frame sizes and I was careful to check all the clearances. This was the perfect motor, but it's speed was 1,725. Not a problem, I'll just change the pulley. I knew that with a larger pulley there could be a belt clearance issue, but I thought I could solve it. What I didn't realize was there would be a pulley issue as well.

It turns out the 12-14 saws use an A belt arbor pulley. All modern pulleys are now sold for a A-B belt. They do this by making the belt groove deeper so the smaller A belt sits in further. Well, an A-B sheave is 3.25" wide where as the A only sheave is 2.5" wide. With an A-B pulley the belts are spaced further apart. If I used the A-B pulley the outside belts would be misaligned by 3/8". I believe this misalignment would be too much for a belt that's only 12" long. It's not feasible to replace the arbor sheave because it would require the bearings to be relocated. The only option would be to go to a 3 belt A-B pulley, but I'd rather not go down that rabbit hole.

At this time I'm not sure what I'm going to do. I'm thinking I may need to pony up for a new $8-900 motor from Grainger and then reuse the stock pulley. Trying to source used stuff certainly isn't saving me any money.

[Van Huskey]

There are plenty of quality 3hp single phase input 3ph output VFDs... On the cheap end Teco (Westinghouse) FM50-203C for under $200.Obviously, you need to look at at the FLA of the motor vs VFD though.

[David Kumm]

Tim, not only are there single phase input vfds, many three phase input will operate with single phase and just hooking up two of the three input terminals. They need to be oversized in some instances but not all. Talk to the vfd guys or give jack Forsberg a call and he will sell you the vfd and talk you through the programming and adjust the voltage output. You should also be able to find a used double A sheave on ebay. My Rockwell has a four belt pulley which was standard on the saw. I think the 3 hp size had the two belts. Changing motors and pulleys is never as easy as you think and often the starter needs swapping too. It is unlikely a 5 hp single phase motor can use the same starter as a 3 hp three phase unless the original starter was not original and oversized. The 7.5 hp for sure would need new electrics. Verify the starter will work with the 5 hp and if so, look for a used pulley. If either is a problem, get the vfd. It is easier to deal with than you are making it. Dave

[Phillip Gregory]

Well, this is turning into a total ClusterMess. The table saw that I bought came with a 3ph 3ph motor. Initially I thought I'd just hang a VFD on it. When I went to order the VFD I discovered, for my prefered brand, that units 3hp and over had a 3 phase input. I don't have 3 phase power. Searching other brands, the only one 3ph option was a Chinese VFD. That won't happen. Not wanting to do a rotary converter I decided to replace the motor. I found a nice TEFC 7.5hp motor on craigslist and bought it. Unfortunately, the motor isn't close to fitting. The housing would be too long for the end cover to fit and the capacitor housing is nowhere close to fitting. Damn.

I then went back to CL and bought really nice Baldor 5hp motor that was new in the crate. By now I was wise to frame sizes and I was careful to check all the clearances. This was the perfect motor, but it's speed was 1,725. Not a problem, I'll just change the pulley. I knew that with a larger pulley there could be a belt clearance issue, but I thought I could solve it. What I didn't realize was there would be a pulley issue as well.

It turns out the 12-14 saws use an A belt arbor pulley. All modern pulleys are now sold for a A-B belt. They do this by making the belt groove deeper so the smaller A belt sits in further. Well, an A-B sheave is 3.25" wide where as the A only sheave is 2.5" wide. With an A-B pulley the belts are spaced further apart. If I used the A-B pulley the outside belts would be misaligned by 3/8". I believe this misalignment would be too much for a belt that's only 12" long. It's not feasible to replace the arbor sheave because it would require the bearings to be relocated. The only option would be to go to a 3 belt A-B pulley, but I'd rather not go down that rabbit hole.

At this time I'm not sure what I'm going to do. I'm thinking I may need to pony up for a new $8-900 motor from Grainger and then reuse the stock pulley. Trying to source used stuff certainly isn't saving me any money.

You got a heck of a deal, not a ClusterMess! A 12/14 in good condition is worth well over 6 bills. Getting the 3 hp 3 ph 208 volt motor to run on 240 volt single phase supply is simple and inexpensive.

Keep the stock motor and sheave, and get the single phase 240 volt input 3 hp TECO L510. I have one of these and it cost about $250, and it can down-regulate the 240 volt supply voltage to the correct 208 volts. The saw will work well and you will be very happy. Don't try to run a 1725 rpm motor on the saw, you will either end up with an enormous arbor sheave that doesn't fit, a tiny motor sheave that has excessive belt slip, or a too-low blade tip speed that gives disappointing performance.

[Matt Day]

If you’re not sure just ask, we enjoy helping. Could have saved you some grief. I just setup an fm-50 last week and have another one in the next week or two to install. Easy peasy.

[Tim Einwalter]

Yea, I already checked the starter and it was a 3hp so it had to be changed regardless. Initially I wasn't concerned because I just use them as contactors to start the vfd.

I've never had a 14" saw so I don't know motor hp vs performance. I know that all the modern 14" saws come with 7.5hp motors so it feels as if a 3hp would be a bit on the light side. If I went back to the vfd option, maybe I get a 5hp vfd and then run the 3hp motor for a while before upgrading. That said, there are several 5 and one 7.5hp 3ph motor option on ebay for very cheap and they have the correct rpm, frame and shaft size.

If anybody is in a market for a 5hp or a 7.5hp 1ph 1725 motor send me a pm.

[Rod Sheridan]

Hi Tim, I doubt if you'll have an issue with the 3 HP motor in a home shop.

I use a 3 phase motor on my bandmill, it's a 2 HP motor, I program the VFD to run it as a 3HP motor as it's hand fed, the load cycle is well within the motor rating...Rod.

[Dave Cav]

Tim,

I've had a 12/14 saw for nearly 10 years now. I bought it from a used machinery dealer, got it home, tore it down and totally rebuilt it. It came with a Baldor 208 volt, 3 phase, 5 HP motor. I have been running this saw successfully with a TECO 3 HP VFD with 240 volt single phase input with NO problems. Yes, a 5 HP motor with a 3 HP VFD; table saws very rarely pull full load amps, and not for very long if they do. I normally run a 12" rip blade but occasionally will run a big 14" Freud combo blade. If I were you, I'd put the original 3 HP motor back on, get a 3 HP TECO VFD from Factorymation,, throw away the motor starter (the VFD replaces the starter), hook the VFD up, and don't look back.

If you go over to OWWM you will find quite a few people have done exactly the same thing.

[Matt Mattingley]

I have one of Jack’s running my three phase 3 hp Lathe, One running my 5 hp air compressor with variable pressure sensors and speed regulation and one running my 5 hp Pk tablesaw.

I also have two rotary phase converter‘s to suit my other needs.

Air compressor is the biggest consumable in my shop. The air 80g compressor cost me about $200. I absolutely love the variable speed on it.

[Tim Einwalter]

Tim,

I've had a 12/14 saw for nearly 10 years now. I bought it from a used machinery dealer, got it home, tore it down and totally rebuilt it. It came with a Baldor 208 volt, 3 phase, 5 HP motor. I have been running this saw successfully with a TECO 3 HP VFD with 240 volt single phase input with NO problems. Yes, a 5 HP motor with a 3 HP VFD; table saws very rarely pull full load amps, and not for very long if they do. I normally run a 12" rip blade but occasionally will run a big 14" Freud combo blade. If I were you, I'd put the original 3 HP motor back on, get a 3 HP TECO VFD from Factorymation,, throw away the motor starter (the VFD replaces the starter), hook the VFD up, and don't look back.

If you go over to OWWM you will find quite a few people have done exactly the same thing.

I had toyed with the idea of using a 3hp vfd with a 5hp motor. I knew it had been done, but I couldn't find any references to it being used on a table saw. What I did discover is that a 3 phase input VFD can be used with single phase power. Apparently you need to derate the VFD to roughly 50%. A vendor mentioned this to me when I couldn't find the right unit on their website. I then got on ebay and found a 10hp VFD for a good price. It was my prefered brand too. I then called the mfr and confirmed that the VFD can be used on single phase power. I'll be limited to 14.5a with a 10hp VFD, but it will work. Currently have a bid on the VFD so now it's just a waiting game...

[Dave Cav]

One running my 5 hp air compressor with variable pressure sensors and speed regulation ... Air compressor is the biggest consumable in my shop. The air 80g compressor cost me about $200. I absolutely love the variable speed on it.

I got a similar deal on a 5 HP 80 gallon air compressor from a shop closing. It's a relatively late model from the Borg. The original owner fried the OEM single phase motor and his electrician put a 3 PH 5 HP motor on it since the shop had 3 phase. When I bought it because I was in a hurry I put an inexpensive single phase motor on it then put a larger drive pulley on the motor to get the operating amps right up to the upper end. Eventually I'll kill it, and then I'll put the 3 phase motor back on it with one of Jack's VFDs.

How did you set up your speed regulation?

[Martin Wasner]

How does varying the pump speed make sense on a piston compressor? Especially a small one?

Generally you don't see a vfd on a compressor until you get into the medium sized compressors on up. Like 50+ hp

[David Kumm]

I could see varying a pump on a Quincy QR type piston compressor. They were built to run from 600-1000rpm and Quincy supplied various motors and pulleys to accomplish that. Most pumps were made to run in a more narrow range or to run fast because they were too small to run slow. My QR 325 just keeps up with an air sander but if I were to do it over, I'd use a 370 with a 7.5 hp motor and dial it back when not sanding. Still not a very efficient way to deliver air but at least the slow put put sound of the old QR are kind of pleasant. Many new compressors are horrible on the ears or don't make much air. A few companies oversize their pumps and slow then down but the build of the pump is way lower than the Quincy. Dave

[Matt Mattingley]

I got a similar deal on a 5 HP 80 gallon air compressor from a shop closing. It's a relatively late model from the Borg. The original owner fried the OEM single phase motor and his electrician put a 3 PH 5 HP motor on it since the shop had 3 phase. When I bought it because I was in a hurry I put an inexpensive single phase motor on it then put a larger drive pulley on the motor to get the operating amps right up to the upper end. Eventually I'll kill it, and then I'll put the 3 phase motor back on it with one of Jack's VFDs.

How did you set up your speed regulation?

Jacks has 4 inputs that are designed in a magic square that can have upwards of 15 calls. This is under what is called simple PLC programming. The original motor was a 3450 RPM. I put on a 1720 RPM but used the same shive dia.( maybe 1/2” bigger). There is the main pressure control switch and then there is 3 different recovery recovery speeds and three more adjustable pressure switches. The four different pressure switches with the toggle switch determine the speed in hertz. I have it set up at 40 Hz, 60 Hz, 90 Hz, 120 Hz, this is the auto program on the toggle switch. When the first pressure switch clicks on at 145 psi the motor cycles at 40 Hz. If I continuously drain the tank using a pneumatic sander at 125 psi it goes up to 60 Hz. If I keep depletin, The pressure at 110 psi it goes up to 90 hurts and anything below 90 psi (which is my operational pressure of most of my pneumatic equipment) it goes up to 120 Hz. And everything is reversed as each pressure sensor is kicked off.

I did this because I work late at night in a bedroom community. I did not like using one blast of air through an air gun and the air compressor turning on fullbore. I did have to fill the oil reservoir a little higher to keep the splash efficient. Yes I know I’m over running the motor at 120 Hz. I only spent 40 bucks on the motor so I really don’t care if I blow it up.

At 40 Hz I am getting about 6 CFM at 62 dB. At 120 Hz I’m getting aboat 17 CFM at 86 dB measured at 8 feet.

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The low speed stops the upper two speed’s recovery(90 &120Hz). The high speed stops the lower two speeds on recovery(40 & 60Hz). The final pressure stop is 175 PSI always regardless of the recovery speed.

I have a three piston pump that is single stage not two stage.

I also built in a Air chiller (using a old dehumidifier that I bought at an auction for one dollar). Air travels through a b vent, then Through a bathtub and I empty the tank about once a month. These past two months I’ve been getting about 2 tablespoons of water. The rest is spit out on the floor at the beginning and end of each compressor start/stop.

[Martin Wasner]

Noise is certainly something I would not have put together.