584,866 active members*
5,200 visitors online*
Register for free
Login
Page 1 of 3 123
Results 1 to 20 of 51
  1. #1
    Join Date
    Feb 2006
    Posts
    794

    Post MOTOR VFD UPGRADED ON BELT DRIVE

    Howdy Fellow IH'ers,
    Some time back, I did the belt drive conversion on my IH and then complained about loosing all my low end torque. I had some things to learn and bought the motor & VFD before doing my proper home work. There were a few others talking motors and VFD'd but I didn't fully understand what they were telling me !
    First off I started with a motor recommendation that was 2hp, 3470rpm motor and I thought to myself, SELF ! ( this parts gets me into lots of trouble) I want to increase my top end speed !
    I also purchased a Hitachi L200 vfd. It is a good unit, BUT !
    What I recently learned, and a few others was trying to tell me, and I really needed to know was this !
    The 3470 motor falls into the 3600 group & is two pole, great for high speed, no low end torque.
    next group is the 1800 or the 1740 motors, four pole ! ! ! This is the work horse motor for our needs. 1740 rpm's and lots of low end grunting torque !
    then there is the 1200 6 pole, 800 8 pole etc.
    Another thing I didn't know was that there is the std motor, and the inverter grade motor, which mainly is of a better grade of insulation and core bonding, wire etc.
    Enough of that, but, If I had been able to read the above before I purchased my motor and vfd, I would have been much happier from the get go ! I could have made a more informed decision, that's why I'm posting this.
    My 2 pole motor on the L200 ran great through the gear box, no problems. But when I went direct belt drive and eliminated the gear reductions, If I slowed the motor down to 20hz (20hz of 60 hz) I could grab the spindle with my hand and stall the motor, NOT GOOD !
    OK, I just bought a four pole motor, C face mounting, still 2 hp.
    Also bought a Hitachi SJ200 inverter drive which is the "Constant Torque" model, and started to test things out.
    I left the 2 pole motor on machine and replaced the L200 with the SJ200 & set up the drive with the goodies turned on and set for two pole. I could still stall motor with hand and saw no real difference with drive and started worrying about $ spent.
    I started the change over to the 4 pole motor, (used, non inverter) I had to make an adapter to extend shaft in order to eliminate the other shaft in box, then since the motor was C face mount I needed to be able to bolt to motor from inside of cover plate, then got it all assembled and mounted.
    All I changed in vfd was from 2 pole to 4 pole then ran motor. Sounded great, I slowed it down to about 8hz which is about 230 rpm and tried grabbing the spindle.
    I'M HAPPY TO SAY IT TRIED TO RIP THE PALM OFF MY HAND ! Now torque up the wazoo, I couldn't even hear an audible drop of rpm's.
    Now I had my low end torque and could start to fine tune the inverter, but first, The SJ200 can over drive the motor from the 60 hz up to a limit of 400hz ! But, since my motor is not inverter graded and may have other limits, I chose to limit my input of 120hz, Now, I still have my 6000 rpm spindle and also my needed and wanted low end torque.
    There are numerous smart and all knowing people on this site. And they knew all this stuff when I was just starting on this project. But, what I try to say above is not what they were saying and so I couldn't even put together an intelligent question in order to make sense of it all. I hope this can help someone who finds themselves in the position I was in then.
    There is more yet to learn, more fine tuning of the vfd, more terminology to absorb, more questions to answer . . . . . . . . . .
    I hope this makes it easier to understand, so maybe that someone, will not have to blunder the way I did, to learn what others consider to be fundamental !
    Don
    IH v-3 early model owner

  2. #2
    Join Date
    Feb 2009
    Posts
    87

    Your post was most informative and with perfect timing. I am looking into a VFD upgrade for my Shoptask and would have made the same mistakes you outlined. I like it when someone post information on actual personal experience and not just what they think will work.

  3. #3
    Join Date
    Jan 2005
    Posts
    15362
    Hi Cruiser

    Something you were doing is not right because your motor you have now is 1740rpm @60hz taking this motor to 120hz will only give you 3480rpm not the 6,000rpm

    You need almost 2/1 belt pulley drive to get to the 6,000rpm with this motor

    There should of been nothing wrong with your 2 pole motor, with 1/1 belt pulley drive
    It's all in your pulley sizing to get the gear ratio correct for each motor

    Both will do the same thing if set up pulley wise to suit each motors rpm
    Mactec54

  4. #4
    Join Date
    Feb 2006
    Posts
    794
    The 6 grand is spindle speed !
    I got some gear ratio involvement in the belt drive !
    thanks for the math lesson tho

    Again, The two pole motor had NO low end torque ! I could stall it by hand ! this was tested with the new SJ drive !
    The four pole motor has BALLS ! I tested it in cut today and with a 3/4" old dull hs tin end mill and it grunted and threw chips !
    I don't think saying that there should be nothing wrong with the 2 pole motor after running this test is saying much, The two pole motor just don't have any LOW END PERIOD !
    trying the same thing with both motors and seeing the results first hand, WELL !
    The four pole was run this morning in cut doing a .15 dp x .025 with rpm at 7.1hz or 500 rpm and didn't slow down at all.
    The old motor, well, I could stop it with my hand so what else can I say
    Don
    IH v-3 early model owner

  5. #5
    Join Date
    Jan 2005
    Posts
    15362
    Hi Cruiser

    Mostly 2hp 2pole motors are on Bridgeport CNC knee mills (there standard motor) & you can not stop them with your hand at 500rpm & that is 1/1 pulley ratio so you had something wrong with your set up for this to happen, It may have been the drive but I think you had the wrong pulley ratio

    I have to agree that they don't have a lot of torque right up to 1000rpm but they can still plunge cut a 1" endmill at that 1000rpm

    If you put your 4 pole motor at the 2/1 pulley belt ratio to get the 6,000 rpm you will have the same problem as you had with the 2pole motor

    You can't have the 2pole & 4pole motors at the same pulley ratio, You can but they won't perform the same at the same pulley ratio

    The thing is if you want speed lots of rpm you go with the 2pole & have a low gear or 2 pulley sets so you change one to high speed & one for the low end rpm

    The 4pole you would have to do the same thing if you want high rpm you can only drive it at 120hz above 120hz on a standard motor & it will not last very long
    Mactec54

  6. #6
    Join Date
    Feb 2006
    Posts
    794
    The Bridgeports that I ran had a dynamic drive and when slowed down the belt ratio was reduced and the motor stayed at top rpm !
    If that were my case I'd agree with you.'
    My belt ratio is 1.76 to 1 or close to that (memmory issue) and does not change.
    If something was wrong with the motor I don't think it would wind up to full rpm, or it would run with lost phase rumble. this was not so and it was gutless at low rpm from day one.
    Don
    IH v-3 early model owner

  7. #7
    Join Date
    Jan 2005
    Posts
    15362
    Cruiser
    You have not seen my Bridgeport head conversions, these have been running for many years they are a 1/1 drive 2pole motor
    Attached Thumbnails Attached Thumbnails Bridgeport Head mod.jpg   Bridgeport with Encoder.jpg  
    Mactec54

  8. #8
    Join Date
    Feb 2006
    Posts
    794
    Well then, Either my motor was defective from the factory or you have a differant type of motor than mine.
    Other than that then your drive must be a lot more potent on the bottom end of the scale and the motor can take it.
    I don't think my old motor is inverter duty and I know my new old motor is not and if your motor is a newer inverter duty or maybe a vector drive motor then I don't know.
    What I'm trying to say is we must be talking oranges and tangerines here !
    The motor ran great at top speed but had Zero low end torque. The new motor has great low end torque.
    What ever the case we are not both on the same page !
    Don
    IH v-3 early model owner

  9. #9
    Join Date
    Jan 2005
    Posts
    15362
    Cruiser
    The motors are standard Bridgeport motors 2pole, & are not inverter duty, the vfd drives I use are general purpose Yaskawa drives nothing special here, but they are very good drives

    Was your biggest pulley on the motor or on the spindle
    Mactec54

  10. #10
    Join Date
    Feb 2006
    Posts
    794
    Big wheel is on the motor, it is set-up for getting rpm's useable for alum. to spindle.
    question ? what is the rated rpm of this motor of yours ?
    Is it 230v ?

    Never mind the questions, I saw one of your threads.
    I conceed, something wrong with other motor ! (no low end capacity)
    Don
    IH v-3 early model owner

  11. #11
    Join Date
    Jan 2005
    Posts
    15362
    Cruiser
    There may of been something not right with the motor but your pulleys should of been the other way round for the 2pole motor you were gearing it up instead you should of been gearing it down the 2 pole motor would of been running to slow to have any torque at 500 rpm

    If your ratio was with the small pulley on the motor & the large on the spindle (1to1.76 ratio)your rpm would of been 5441rpm at 120hz ( these numbers are all aproximate )

    So at 500rpm at your spindle the motor would of been doing 880rpm which would of had much better torque & most likely you would not of stopped it with your hand

    The motor would of been running at around 284rpm with the big pulley on the motor & the spindle would of been running at 500rpm you can now see were the problem was with the motor speed at 284rpm you sure could stop it very easy but at 880rpm it would of been very hard to stop
    Mactec54

  12. #12
    Join Date
    Jan 2005
    Posts
    15362
    Cruiser

    Some more for those that want to change there machine to belt drive It does not matter if you have a 2 pole motor or a 4 pole motor if you have the gearing/pulley ratio correct & the right VFD to do the job

    If you are wanting around 6,000 rpm, then the ratio for a 2pole motor needs to be around 1.13/1 on a 3470 rpm motor this will give you 6,141rpm at 120hz, the biger pulley goes on the spindle, (all numbers are approximate)

    If you have a 4pole motor with 1740rpm & want the same rpm then the gearing /pulley ratio will have to be 1/1.76 this will give you 6124rpm at 120hz, on this one the big pulley goes on the motor, ( all number are approximate)

    There are other things that come into play as well, your VFD drive will also have to have the correct set up & right rating to drive your motor

    If your VFD has a 230V 3ph input & you want to run it on 230V 1ph then if your motor is 2Hp your drive would have to be 4Hp rated or more usually it would be a 5Hp rated drive to do the job

    If you buy the right drive for single phase rated input your drive then can have the same Hp rating as your motor
    Mactec54

  13. #13
    Join Date
    Mar 2004
    Posts
    41
    Cruiser,

    I too have an older 10" IH mill that is set up with a belt drive and VFD. I'm the second owner of the machine. The original owner purchased the machine from IH back when Aaron was running the show. Aaron did all of the conversion on the machine. I was told that this machine was basically the prototype mill for Aaron's development of a production belt drive set up. I think he decided that the conversion was either too much trouble or too expensive to persue. All this is based on my conversations with the original owner of the mill. I have never spoken to Aaron myself.

    Anyway, the machine is set up with a Leeson 2hp, 3479 rpm motor. Right now I can't remember the specs on the VFD, but it is single phase input. I have no idea about the pulley ratios because I've never looked inside the head, but I would guess that it may be set up at 1:1 (or close to 1:1) because the spindle is limited to 3900 rpm by Mach3. To this point I've never needed any more rpm, so I've never tried to run it any faster.

    The machine has plenty of torque even at low rpm. I guarantee that I could not stop the spindle by hand at 500 rpm. At less than a 1000 rpm it will plunge a 3/4" endmill into aluminum with no problem.

  14. #14
    Join Date
    Feb 2006
    Posts
    794
    Flathead, Do you still have the advantage of the gears set ? My box was gutted out !
    I ran some cutting tests and found that my gear ratio of 1.71/1 was too high even for the 4 pole motor, I have ordered another wheel and belt to drop back to a 1/1 ratio. I'll miss the top speed for aluminum, but I really must get the low end torque for steel. I wish that I could have salvaged my gear set, but it was toasted / noisy. I should have the parts middle this week.
    Now I think that I may sell my old motors and vfd. the leeson with the vfd as set and even the original motor came with mill and never powered.
    Don
    IH v-3 early model owner

  15. #15
    Join Date
    Jan 2005
    Posts
    15362
    Cruiser

    If you put your 2 pole motor back on you will still be able to get some higher rpm & gear it down for the low end rpm that you need just have 2 pulley sets, for your low end you want 1.5/1 to 1.8/1 that is the big pulley on the spindle & a 1.1 set for your high rpm you could still get 6,000 at 120hz with your pulley set of 1/1
    Mactec54

  16. #16
    Join Date
    Jan 2005
    Posts
    15362
    flathead

    If they have your VFD set to 120hz, then you will have a pulley ratio aproximate 1.76 /1 this would have the large pulley on the spindle & this will give you the 3,900rpm
    Mactec54

  17. #17
    Join Date
    Mar 2004
    Posts
    41
    Cruiser,

    I don't have the gearset either. But I have another IH manual mill that still has the geardrive spindle if I need some extra grunt for some reason. I'm considering selling it though, because I very rarely use the manual mill.

    Mactec54,
    Two pulley sets sound interesting. It would be nice to be able to change out the pulleys and be able to achieve some higer spindle speeds. I only cut aluminum and plastic on my machine, so I could use the higher rpms sometimes. My only concern would be the spindle bearings. How much rpm can these bearings take? As my machine is now, I think my bearings are worn to the point that I need to replace them. I'm not able to cut aluminum with a 1/16" endmill without breakage no matter how slow my feedrate. But I can use an 1/8" endmill all day long without any problems. Spindle runout is definitely an issue. When running at higher rpms I can hear some noise from the bearings. I just haven't had the nerve to try and replace the bearings yet. I don't use the machine for production work, so its not that big of a deal right now.

  18. #18
    Join Date
    Feb 2006
    Posts
    794
    Flathead
    The spindle drops out real easy and there is no reason to not drop it out and check it out. I have a spare set of bearings in the shop so I can get you the numbers to order some good ones the are good to 9,000 with grease. Not that I'd run the spindle that high. It could be that the bears have become loose and only need to be relubed and reset, If you can feel any shake at the spindle then I'd pull and check it out for sure.
    I wish that there was more room in the box for two pulley set-up and an easier way to get to it, I may must build myself a new box and set it up myself.
    Don
    IH v-3 early model owner

  19. #19
    thanks for the documentation, I've been planning something like this for the summer on both my mill and South Bend.

  20. #20
    Join Date
    Mar 2004
    Posts
    41
    Cruiser,

    What is the procedure for removing the spindle? Can you give me a step by step?

    I think I have a spare set of bearings for it already. I also have a spare spindle and what I believe to be a "tool" designed to remove the spindle. The "tool" is made out of a section of 1 1/2" (?) metal pipe about 24" long with a cap on one end. I suspect it is to be used to drive the spindle out of its bearings. But I'm not sure if it comes out from the top or bottom. I've never really investigated it.

    Any help is appreciated.

    thanks

Page 1 of 3 123

Similar Threads

  1. Question - X2 motor isolation for belt drive
    By george4657 in forum Benchtop Machines
    Replies: 4
    Last Post: 08-21-2009, 02:00 PM
  2. Belt drive X3 conversion. New motor too?
    By Thorpydo in forum Benchtop Machines
    Replies: 5
    Last Post: 03-15-2009, 07:05 AM
  3. Looking for Motor upgrade suggestions for X3 w/Belt drive
    By dneisler in forum Benchtop Machines
    Replies: 7
    Last Post: 05-02-2008, 10:54 PM
  4. Replies: 2
    Last Post: 04-12-2008, 06:16 PM
  5. Stepper Motor Belt Drive Side Load Question
    By harryn in forum Stepper Motors / Drives
    Replies: 3
    Last Post: 08-07-2007, 11:23 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •