VFD on combination machine

[Michael Cummins]

Hi all,

Long time reader on SMC, but just registered to ask a question I haven't been able to find much info about.

I'm likely buying a Robland x31 combination machine (the original 5 function machine that all the others today have copied). Its got 3) 4HP 3 phase motors, with one control panel that selects which motor to turn on, a power on switch, and several cut off switches around the machine near the various stations. Its currently being run on a home built rotary phase converter, but I was thinking of going over to a VFD setup.

https://images.craigslist.org/00x0x_fDOEysexHd7_1200x900.jpg


I know in general you're not supposed to run multiple motors on one VFD, but was wondering if this setup where only one motor at a time can be selected to run at the control panel would be different, or would I have to split up the controls and run 3 separate VFDs on the machine? In the photo below, you can see the control board under the slider table. There's stop, then start button, then the knob to the right of that selects which motor will run. Knob below that I think is forward/reverse for the shaper motor, but not positive.


https://images.craigslist.org/00c0c_g1Kfwx7XQlh_1200x900.jpg

Also, I've read on here, I believe, that most 5HP machines will run pretty much at full normal rated load on a 3HP TECO due to the 50% overrun, which under most woodworking conditions would only happen rarely with such large motors... so with my 4HP motors, would a 3HP be sufficient? Would save a lot of dough. I plan on using the sliding table saw a good bit, the shaper a reasonable amount, and the jointer/planer only occasionally (use dedicated machines, but the planer can be a nice backup if I have an issue, and my regular jointer is 8", so when the need for a 12" jointer pops up, will be nice to have - but don't want to have to change machine setup every time I joint). This particular machine has the mortiser removed and mounted on a separate stand with its own motor (which is great, that thing seemed like it would be in the way).

Any thoughts on if a single VFD is feasible to just tie into the existing controls, or does all that have to be completely reworked if I want to go to VFD? I'd just like to get rid of the extra noise, size, hassle, and inefficiency of the rotary converter if possible.

Thanks for the help. I'm still new to phase conversion, but keep coming across great deals on 3 phase equipment and trying to learn.

Mike

[Patrick Kane]

Hey Mike,

Im by no means an expert on VFDs, ive only wired one myself. However, I think what you want to do is possible. My Felder from the mid 2000s is two 3 phase motors wired to a central VFD and controlled via two switches. It is delivered single phase from the factory, but is actually 3 phase motors. I havent looked inside the control box to see if its one or two separate VFDs, but im sure your can mimic the setup for your machine. The one point of confusion i have is the VFD has to be connected directly to the motor leads, and im confused how you do that with 3 separate motors and switches. In this situation, i think an RPC is the easiest and simplest solution.

That machine has sat out there for 6-8 months, if my memory is correct. You are in Pittsburgh, i take it?

[Rod Sheridan]

Hi, yes you can do it with one VFD.

I've converted 2 machines so far.

The easiest method is to use the VFD as the main contactor/overload device, you'll need to wire all the start/stop pushbuttons to it, as well as any safety switches such as door or hood interlocks.

I disabled reverse on the VFD and used the machine selector switch to switch the VFD output to select saw, jointer/planer, shaper forward and shaper reverse. Some machines have jointer reverse as well for the mortiser.

The machines I converted had DC injection braking so I removed that and programmed the VFD to provide braking. I used a 3HP rated VFD.

The machines I converted had a disconnect switch, I put a label above the function selector to warn to open the disconnect switch and wait 10 seconds before changing functions.............Rod.

[Michael Cummins]

Hi Patrick,

Thanks for the input. Sounds like it is doable. Assuming I get the machine, would probably run the RPC for a while, but wanted to know if it was possible ahead of pulling the trigger, if I do so.

Yes, I am in Pittsburgh. You too?

I'm aware of it being for sale for about a month so far. Not sure beyond that. Any thoughts on it? I wasn't looking for a combo machine or per se a slider, but thinking it could work out well for my needs if I can get it for the right price.

[Michael Cummins]

Thanks Rod,

This is very helpful information. If I end up doing this, might have some follow up questions for you, but def glad to know it can be done and not need to completely rewire machine with 3 VFDs... that would be a pain and expense I'm not excited about.

What VFD unit did you use or would you recommend? Was looking at L510 from TECO based on lots of positive comments about it on here, but I know next to nothing about these things and would value your experience.

[Patrick Kane]

If you havent programmed or wired a VFd previously, i might suggest reaching out to Jack and buying one from him. I recently purchased a 10hp unit through him for a 5.5hp jointer and thought it was pretty reasonable. The real value was having Matt walk me through programming the device for the motor. I wired my whole shop, and im competent to that degree, but programming the VFD would have been a frustrating hour or more. With Matt on the phone, i did it correctly in 7 mins. I dont know what a 5hp unit would run, but mine was under $400 shipped to my door. Keep that in mind if you arent confident or experienced heading into it ahead of time.

Yep, in the south hills. I swear i saw that same machine many many moons ago. The clock you are looking at was most likely reset a few times by the poster deleting and reposting it. I have not used or seen a Robland machine in person, so i dont have an opinion on the specific machine. While Robland is european, think its on the economical end of euro manufacturing. Just because its European, doesnt mean it has the same build quality as Martin. With that said,i dont think i would touch this machine for my own purposes. I simply dont know enough about that sliding table design to buy into it. I would do my research on this machine before going to check it out. A lot of the old slider designs had carriage ways that could/would wear if not properly maintained or from 30 years of use that would make them crap. Even a little bit of slop in the carriage stroke would make it somewhat useless for fine woodworking. Next, i dont know how that machine adjusts. This is another thing that i believe has come a long way over the last few decades. Heck, i think there are major differences in adjusting my 2004-2005 Felder versus a 2000 Felder 700, or a 2014 Felder 700. This is a huge deal for the slider, and a mildly big deal for the jointer. Dialing in a whackjob sliding table to precise tolerances makes tuning any other machine seem like a walk in the park.

$2500 isnt awful, and if the jointer tables are flat and able to be adjusted properly then it could be a great addition to what you already have and plan to keep. I wouldnt want to use that thing as the only machine in my shop, but if it was to be a dedicated 12" jointer with the slider, then that sounds like a worthwhile investment. Does the guy have the table saw and jointer fence? How about a jointer guard? The stroke of the slider looks like the awkward tweener length of 6-7' like mine.

[Michael Cummins]

I have not done a VFD, so yes, any help would certainly be great. Especially since this is probably a significantly more complicated setup than typical. Sorry if I should know this as a SMC user, but Jack who? I'm happy to reach out to him. Thanks for the reference.

May have, the guy is retiring and may have had it listed a long time. I won't pay $2500, but if I can get it a bit cheaper would consider it. I've looked into the machine a lot and not seen any major issues yet, just some fiddly stuff like the way you raise/lower the table saw blade. Its nice as you can raise it full height or drop it full in one motion, but fine adjustment is a little finicky. The other thing I'm not sure I'm sold on is that the slider isn't right up against the blade. As someone who's always used contractor/cabinet style saws, that might be useful for me in some ways, but def not the norm for sliders. I'll check out the sliding mechanism and adjustment methods carefully before buying - thanks for that tip. I've seen the machine and it seems very solid, and the owner ran a production shop and definitely knows his stuff, so that helps a bit too. It does have the jointer fence and TS fences - not sure if it has every original accessory or not though. Not sure about guard for jointer, but not overly worried about that as I won't use it that often.

It would be probably be used as 85% table saw, 10% shaper, 5% jointer (only when I need larger than my 8" dedicated jointer), and backup only planer. The mortiser is separated with its own stand/motor, so no re-configuring there.

Nice to meet someone nearby - I live in Lawrenceville. We should grab a beer or something sometime. I'd love to talk shop with someone else in the area who's willing to buy some more professional grade equipment. Most of my woodworking friends have just very basics or are mostly hand tool guys. I don't have anything too crazy yet, and am in the process of designing/building/getting city approval for my new shop that will be on 2nd floor of a 2 car garage. Crazy setup, but should work well for my urban environment. Collecting nicer equipment now for when the shop is done. Can't wait to put it all to use again rather than working out of a basement or with portable tools.

[Ben Ridgway]

Hey folks! I know this is an old thread but I’m finding myself in a similar situation and wondering what the outcome/solution was. I’m debating purchasing a X31 which seems to be in good shape but it’s 3 phase which I don’t have access to. Michael, if you read this, would you kindly let me know if the VFD situation worked out for you? Thanks! Long time lurker here, finally joined up…

[Aaron Inami]

I don't know that doing a VFD in this situation is really worth the effort. You would have to massively re-wire and re-design all the circuits and safety-interlocks. The entire control circuit panel inside the machine is designed for 3-phase input, so it's likely you'd have to completely throw it out and start new.

[Larry Edgerton]

Interesting question. I have a Clausing drill press with a two speed motor I wired to a VFD, and my research showed me I could wire to the motor speed selection switch and still have both speeds AS LONG AS I DID NOT CHANGE SPEEDS WHILE RUNNING. Has been fine and I am the only one in my shop. Seems like your situation would be similar.

[Bill Dufour]

As long as all three motors are similar rpm, hp, and amps should be fine. You will have to turn off the vfd before switching to a different motor or using a reversing switch.
On my lathe I kept one contactor as a master power switch because my vfd idles when power is present. Just turn off vfd then turn off power into it. Similar to pulling the plug after shutdown. My cheapskate ears do not like the sound of the vfd fan running hours/days after the last use.
Bill D

[Ben Ridgway]

Thanks for the input guys. I’m a little ignorant about electricity at that level. My understanding is that the X31 machine has (3) 3 HP motors but I’m unsure of the RPMs. The machine being sold is about 3-1/2 hours away from me so it’s hard to gather all the info. I certainly don’t want to buy something that needs tinkering I can’t do and parts that are thousands of dollars. It seems like a unique situation with the 3 different motors. I called my local electrician friend to ask advice and he couldn’t give me any without looking at the machine…

I’m building my first shop for myself now. I was a carpenter for 20 years then worked in an older but high quality cabinet shop for 6 years. I don’t have space or funds to build anything like what I recently was working in but I’m hoping to get something set up to make cabinets, small furniture, etc.

Thanks for any wise words!

[Rod Sheridan]

Hi Ben, separate motors for each function are common in combination machines, nothing unusual.

I own a saw/shaper and a jointer/planer.

A VFD is a good solution to your prospective machine requirements

Regards, Rod

[Chris Parks]

We all agree that VFD's should be dedicated to one machine as a general rule and simplicity but I had an old customer call me because his VFD had committed suicide after 10+ years of service and I am still baffled about the way he was using it. He has a small commercial joinery and bought a VFD and Clearvue from me as all Clearvues in Oz are 3 phase but what he did next leaves me entirely baffled as how it has worked at all. He reasoned that the VFD provided 3 phase so he made up a dedicated 3 phase board and that board supplies 3 phase to multiple machines with no regard to how many were running at once or how they were started and stopped using the machine controls. Apparently the VFD was switched on at the start of each day's work and the machines used normally as would happen in a shop that had 3 phase power from the grid. I have been supplying VFD's for many years and I couldn't believe that the VFD didn't die after the first day so I bailed out not wanting anything to do with it and handed him over to a friend who has enormous commercial experience with VFD's and I am yet to hear back from him on what happened. I am still shaking my head over the whole thing and I must chase it up to see what happened.