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Thread: Three phase static inverter questions...OMGA RAS

  1. #16
    Join Date
    Feb 2011
    Location
    Central WI
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    5,666
    Thinking some more if cost is a concern I would still put a 3 hp vfd rather than a static converter on the saw. The vfd will allow for short periods of overage and deliver at least as much amperage as the static. The cost would then be close to the 200-250 range. Would also have a soft start. Dave

  2. #17
    Join Date
    Mar 2003
    Location
    Upland CA
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    5,548
    OK, the deal is finished, the saw is on my truck, and I can explain a little more. I now own an OMGA RN900. It is a 5HP 3 phase, saw that does about a 37" crosscut. I had no idea how large that arm was till I actually saw it in person....from one end of the arm to the other is over 56". I will write a better story about it as soon as I can figure out how to post a pic. Short version: I paid $100 for it. The motor does not want to spin, but from what I can find on the internet, there may be a brake that will not let go till the switch is tripped. It has some rust on the ways, but they are easily replaced ($?).

    Again, in the pics on the OMGA website the stand looks spindly, compared to my DeWalt 7790. In person, the frame is 1 1/2 by 3" heavy wall square tubing, all welded together, and the legs are about three times as thick as the DeWalt, plus they wrap around on three sides.

    So, as far as money goes, I have a bit to spend because of the price, but if the motor turns out to be bad.......? I probably will not be able to spend much time on it for a while, as the kitchen needs finishing first.

    So, thanks guys, and any additional info will be valued.

    Rick Potter

    Long story to follow. With pics.

  3. #18
    Join Date
    Nov 2008
    Location
    Northern Oregon
    Posts
    1,820
    Quote Originally Posted by Rick Potter View Post
    I now own an OMGA RN900. It is a 5HP 3 phase, saw that does about a 37" crosscut.

    .
    Good for you Rick. Now you can crosscut all the 37''wide boards you can find! I have a Dewalt with 16'' and once in a while I wish for a little more, but WOW.

  4. #19
    Join Date
    Mar 2003
    Location
    Upland CA
    Posts
    5,548
    Yup, wow, Andrew.

    What I actually want is an OMGA RN450, with a 24" crosscut, but after looking for a couple years, I couldn't turn this one down. I also have a DeWalt 7790 12" that I use every day. Love it. The OMGA will roll into the corner and be used mostly for cutting cabinet sides and the like. Luckily I have room for it.

    Rick Potter

  5. #20
    Join Date
    Dec 2008
    Location
    Northern Michigan
    Posts
    4,973
    I checked just for the hell of it, and the proprietary motors for that saw are not all that bad. Under $500. I was expecting more.

    $100. You suck!

    Larry

  6. #21
    Join Date
    Mar 2010
    Location
    Grottoes, VA.
    Posts
    905
    As I recall in my research when I put a VFD on my PM66, you can put a 3hp rated VFD on your saw. It will simply de-rate and supply your motor what the VFD is rated for. A teco FM50, rated for 3hp can be had for $185 plus shipping. And when it comes to saw blades, the brake is a nice thing to have.

  7. #22
    Join Date
    Mar 2003
    Location
    Upland CA
    Posts
    5,548
    Larry,

    That price sounds really good to me too, and I would like to check to see if a 3HP single phase is interchangeable, and how much it costs. Might be a great answer. Could you give me contact info for the place you checked?

    Kevin,

    If a three HP VFD would really work and just derate, as you say, that would be plenty for me. I cannot imagine ever cutting anything but sheet goods anyway. I am going to check with Teco.

    I got the saw off the truck in pieces today, and will put some casters on it and get it back together tomorrow, then I will see if the brake is hung up, as I said in an earlier post. It was touch and go with two of us trying to remove the stand from the truck, while I had the arm, motor, and post hanging from the hoist. That thing is HEAVY.

  8. #23
    Join Date
    May 2009
    Location
    N.W. Missouri
    Posts
    1,564
    Watch the ratings on the VFD. Many will de-rate when converting single phase to 3 phase. That means a 5hp VFD running on single phase will only supply 3-4 hp. It has to do with the amps per phase and the electronic components in the VFD.

    I discovered this when deciding how to power a 5hp 3ph PM66 when I bought it. I ended up installing a single phase motor that I had on hand.

    John

  9. #24
    Join Date
    Dec 2008
    Location
    Northern Michigan
    Posts
    4,973
    I checked on the motor direct from OMGA. I did not look to see if they had single phase motors, but it seems like they do not or I would have bought one. I hate having to start my converter just to cut a board. There is a Phase Perfect in my future.....

    Mine is an RN 700. I thought about the one you have but I did not need that much capasity and did not want to have to walk around the arm all the time. Mine is too long as it is, but I have a table that bolts to it that brings the fence out a foot for some jobs where I want to hold pieces on both sides of the saw. Saves the walk around. I just unhook the automatic retract coil when I use that fence.

    Like I said earlier, there is no comparison between this saw and the 16" delta that I replaced.

    Is your saw 14"? I have a couple of brand new Leitz built Delta 16" blades from the old saw sitting around.

    I can't see any reason that you could not cut the turret arm down if after some time you find it is not necessary.

    Later, Larry

    PS: I have some 36" wide Jatoba boards in my shop that I can't cut with mine. I'm just saying......
    Last edited by Larry Edgerton; 08-31-2012 at 8:42 PM.

  10. #25
    Join Date
    Mar 2003
    Location
    Upland CA
    Posts
    5,548
    Well,

    Sorry to be so long getting back to this, but the saw is now off the truck, and on wheels. I have a cheap HF hoist in my garage to unload heavy things. Only problem, the saw on it's stand was too high to get in the garage door, so it sat in the truck for a while. Couldn't even use the old deflate the tires trick.

    Had to remove the arm from the saw, lay it on the saw table and drive in. Then removed the arm with the hoist, and two of us removed the table. Yes it is that heavy (or I am that old). Put a simple base with wheels on the stand, then using the hoist, put the arm back on, and rolled it out to the shop.

    The motor is sort of locked up. The shaft wiggles, but won't turn, and I don't want to force anything, so I called OMGA. Turns out there is a very strong electromagnetic brake which locks up the motor when there is no power. When you turn on the switch, it lets go.

    I asked about getting a new single phase motor for it, and they have one available for $887. It is a two HP model (I assume that is REAL HP), and fits the frame of my RN900. A new 3 phase motor is $830. He didn't know anything about a sub $500 motor. Maybe I am getting the retail price, and Larry E. got the commercial price?

    The steel strips on the arm, that the trolley rides on are only $16 each (takes 4), and seems better than cleaning up what is there.

    So here we are, kind of like catching a tiger by the tail. It's in the shop, now what am I going to do? I figure it is well worth putting the new motor on, or buying a good converter. By the time I put the table on, wire it, new wear strips and all, I will have about $1200 in the saw. Right now, on E-bay, there are three OMGA's for sale....all at the $2400 mark, and looking no better than mine. My only problem is that I really wanted the smaller one that cuts 27". Boy I would hate to cut the arm on mine, but that's what the OMGA guy suggested.

    What to do, what to do.

    Rick Potter

    PS: Took pics, now need to figure out how to post them again. I downloaded the Olympus program that came with my point and shoot, but it seems to be having trouble getting along with the Corel program the old pics are on.

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