More electrical help needed – jointer this time!
madphilip
| Posted in General Discussion on
You all were very helpful in getting me sorted out on my 3hp Delta Unisaw – I had an electrician drop a new garage outlet to handle the need. Now I’ve gone picked up a ~1981 Rockwell 37-220 jointer. Surplus from county school system. Looks like it spent it’s whole life sitting but barely used. As pictured, it has a 3hp motor, the largest size the manual recommends. The plug on it (sorry, no picture) has four curved prongs in a circle pattern. Here’s my question – can I put a new cord/plug on this tool that mirrors the cord/plug on my unisaw? The outlet put in for the unisaw is 220/240. I thought this jointer would run on a normal outlet but I guess the school shop teacher went very Tim Allen on the motor selection!
Replies
You cannot change the plug as it is a 3-phase motor, as indicated by the tag.
However, if your Unisaw is also three-phase 230V and has some type of alternative plug, you could change it to match.
If you don't have 3-phase power from the grid, you can buy a VFD or other phase converter.
That will take your 230V single phase and supply a 3ph output.
Your plug is a NEMA L(Non-L maybe)15-15 (or 30), which is the standard plug for 230V 3phase in the US. I'm unaware of an alternative plug for that application.
If you're doing a VFD, you'll most likely just be hardwiring it into the VFD outputs. You could make an L15-30 whip off the VFD output if you wanted. It would be a little goofy, but there is nothing wrong with it.
VFDs are very affordable these days. You need to search for a 5HP 230V VFD. I know Vevor makes them.
There is no issue with lower-price VFDs either. Not for this application.
Now, for constant-duty motors, that is a different story. You will have stray currents running through the rotor and, thus, the bearings that will eventually cause your motor to sound like a freight train. It takes many years, though, and that is for 24/7 applications. It also doesn't affect amp draw or operation either.
External ground assemblies mitigate or solve that issue, which you could also look into if you're worried.
Another cheap solution for that is to just throw a reactor on the input and choke on the output.
Last note: You will need to get a 5hp drive, NOT a 3hp. This is to compensate for the extra phase it adds.
https://www.vevor.com/variable-frequency-drives-c_10745/?utm_source=google&utm_medium=cpc&utm_id=20100279995&ad_group=152446784561&ad_id=657724103506&utm_term=vfd%203hp&gad_source=1&gclid=Cj0KCQiAhvK8BhDfARIsABsPy4j7IROZvSj1n4mhgAhJ3P4kLjFznNIMsq_3dp0R3WWKpo-PX3YZdKIaApEPEALw_wcB
Thanks for such a comprehensive answer! A lot here for me to digest. Given my hobbyist level workload, I'm leaning towards a motor replacement that hopefully will be able to run on the power I've already had run for the table saw. I've seen a few YouTube videos where VFDs were added to vintage tools but now I understand better why they did that.
Correction to my original post...it's a 3/4hp motor. Not a 3hp motor! Based on this correction, what hp VFD would you say I should be looking for?
2X whatever you decide.
Setting it up is easy. Follow the manual, but you'll only need to enter the voltage, RPM, and Hp/Kw in the parameteres. It's all on that nomenclature plate you posted.
Now, if you want, you can set other functions, but you don't need to.
You bring your single-phase line voltage to 2 of the input terminals.
Then, you'll take the 3 motor leads and put them out the outputs. Don't worry about what goes where for the motor leads. If it's spinning the wrong way, just swap any 2 of those wires, and it'll reverse.
There will be what's called a digital/binary input, and one of them is the enable signal. You'll simply break that with a switch somewhere. This will be your "ON" switch, basically, and you could just leave the machine on all the time. It won't run without the VFDs' enable (on switch).
that will get you rolling.
Now, if you want speed control for some reason, you can do that, too, simply by buying a 0-10VDC signal generator and wiring that into one of your analog inputs. Again, all the designations are in the manual. That would allow you to ramp it from 0 to 100% with a little dial.
While I do think this is a very DIY-friendly project and low-cost, I highly suggest you do your research and learn what you can before diving in.
Watch some more videos. Plan on making or buying a little panel to house everything.
I suggest calling Vevor and simply asking if the VFD you decide on is capable of what you're trying to do.
If you do go for it, you'll learn a lot and be really satisfied in the end. You'll also save a lot of money.
I also think the single-phase retrofit is a great option for you. Personally, though, I'd like to keep it original.
If you get stuck, feel free to email me at [email protected], and I'd be happy to help out.
That is a 3 phase motor. It will not run on your existing circut. You can get a phase converter or inverter or replace the motor.
Replacing the motor may be your best bet ( match the frame type on the faceplate for the correct fit.). Check with your local rewind shop for your options.
Thanks for the help! Leaning towards a motor replacement seems like the way I will probably go. The manual suggests 1/3, 1/2 and 2/3 hp motor options and finding a 1/2 or 3/4 that I can run on my existing table saw outlet seems like the simplest path to get it running.
I think that is your best bet. I would advise you get a bit more hp if your circuit can stand it, 1-1/2 or 2hp. You don't want it to bog down when facing full width hardwoods, which gets old very fast, remember, nothing exceeds like excess....
Again I would recommend you check with your local rewind shop, I have always found them very helpful. They may have one used or a reasonably priced new one. In any event match the frame type for a seamless fit.
I think VFD is the way to go personally, but if you don't have the basic prerequisite electrical knowledge, then I second contacting your local machine shop. They are generally experts in this topic and will likely have a lot of good information for you if you stop by and chat with them for a while.
Beyond that, I would call (or visit is a better option if you've got one nearby) Grainger and see what options they have for 230V single phase motors that match your frame type.
They aren't usually the cheapest, but they are very good at finding options you can then just purchase elsewhere.
You definitely don't want a fractional horsepower motor for that machine. I would upgrade to as large as you can.
Also congrats!! it's a nice-looking machine. Im jelly.
Thanks again! I'll be looking at the VFD info this weekend to get educated. I appreciate the comments about going up to higher power if I won't be running 3-phase. I wouldn't have thought of that. I think I just need to make sure whatever solution I use will be turning at the correct RPM...but if I can get more power at the correct RPM, that seems like a good thing!
There are definitely plenty of higher-power motors at the same RPM.
Motor RPMs are standardized.
That is a normal 1725rpm motor. Every size motor produced will have a 1725 option. You just have to make sure the frame size is the same so it fits.
Check out Graingers. They are great for sourcing motors. especially weird ones. They will find the current ones part number and just look up a match at whatever size you want.
You take that part number and shop around if their price is stupid. Which it often is. Grainger likes to mark up everything 4x or more.