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Excello 602 way wiper and VFD conversion questions

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  • Excello 602 way wiper and VFD conversion questions

    My excelllo 602 mill is in the need of some new way wipers. I doubt I can even find new ones so I will need to cut some of my own. What type of felt should I be using for the wipers? I will most likely just order it from McMaster Carr.

    Now on to the VFD question. The mill currently has the factory 1.5 hp motor and vari-speed drive on it. I don't have 3 phase or a decent converter so I will most likely power it with a VFD like I did for my lathe. At some point I will probably go to a direct drive and use the VFD for speed control and ditch the vari-drive all together. I understand there are some trade offs with the drive and not having full power at varying hz. I know the vari-drive system also eats some hp from the motor.

    My question is, would you up the hp of the motor if going to direct drive and VFD speed control. I did this on my lathe when I did the direct drive conversion and went from a 2 hp to a 3hp motor. So far I have not seen a lack of power even when the hz are turned way down but I also don't push the lathe to the limits. I doubt I would be pushing the mill to the limits either. I have the lead on a 3 hp motor that I could make work. Would this be overkill or should I look for a 2 hp motor or even just keep the stock 1.5 hp motor. Does the vari-drive system eat about as much power as a VFD at non-optimal hz does? As far as the 3hp, I know it will be a lot heavier than the factory motor. I don't know what the vari-drive components weigh but should I be concerned with the extra weight up top? Thanks is advance.

  • #2
    Felt -buy F1 and cut your own. A 12x12 piece will last you a lifetime.

    The varispeed has losses BUT it increases torque as the output rpm is mechanically decreased maintaining (mostly) the hp output. The VFD has constant torque below 60hz and as you wind down the hz, hp decreases...

    If it's in decent shape leave the vari-speed in place and use it as required. I have the BP 2hp (3 hp for 20 minutes) PIG (inefficient glutton) motor. I set my "60z" speed to the 4200rpm position on the varispeed dial. If I need more torque at slower hz than I can get at that position, I just wind the handle down and up the HZ. If I need more then that, I flip to back gear (rarely). I run mine up to 90hz - 6K rpm, but run out of grunt at the low end (below 1000rpm, which is when I wind down the varispeed. Bigger drills and larger cutters is when I see the problems - very easy to stall the vfd on a 5/8 drill at 700 rpm on mine unless I wind down the varispeed. I monitor the vfd output current for tool wear and can easily suck the full motor capacity when roughing (25-30% +/- lost to the varispeed).

    For direct drive (I've looked at it) I'd go with a 5+ Hp 1750rpm motor and 1:1.5 (stepping up) belt drive. Using a 5hp motor at 10hz - you'll only have 0.8hp from the motor, and about 260 rpm; at 90hz a shade under 4000 rpm. 10hz is pushing it; I run 15hz minimum. Your selection of "gearing" for the direct drive depends on the range you want, and whether you want lower or higher speed operation bias.

    BTW.. Don't sweat the motor weight...
    Last edited by lakeside53; 04-26-2014, 02:18 AM.


    • #3
      On my 602 I bought sheets of felt and cut out the way wipers my self, a sharp exacto knife works wonders. I also run two VFD's , one for the mill motor and one for the cross feed power. I use both the veriable drive and the VFD. I got my VFD's at I mounted the VFD's to the head of the mill so they are in easy reach.


      • #4
        A good conversion for a VS drive vertical mill is to use a 3hp 3600 rpm TEFC JM frame pump motor to take advantage of the long shaft and the extra power.

        That motor running a 1.35:1 belt reduction would give you 5333 rpm @ 120hz and 888 rpm @ 20hz in high gear with more than enough power to handle anything that will be ran on an R-8 spindle.I forget what XLO used for a low gear ratio,but that reduction should get you to a bottom end around 100rpm and still have plenty of torque.
        I just need one more tool,just one!


        • #5
          I have converted a couple of 602's they were however 2hp, the 1.5 option had a different head casting.
          I used a 1:1 ratio timing belt/pulley to eliminate the vari speed, the advantage on the 602 is it has the 1:1 and 1:6.2 gear box which handles the low rpm's.
          I picked up some commercial way wiper strips that you custom cut, but I would have to look for the source.
          The other thing on the 602, is to replace the metering devices on the way oil system, if they have never been changed, the chances are a couple or more are blocked, check the oil on the individual ways.


          • #6
            Graingers stocks felt in strip rolls in different grades. One of the grades is listed for machine tool way wipers. I bought some a few years back and it worked out great.


            • #7
              BTW, I was told by Excello that they recommended going over to ATF for the G.B.,


              • #8
                Take a look at SAE Hydraulic Pump Motors by LEESON.


                • #9
                  Thanks for the replies on the felt, I'll get a sheet and cut it up.

                  I haven't ran the head on this mill yet so I will see how the vari-drive works before I decide on doing the direct drive. There was supposed to have had some work done in there before I got it.

                  Max, the oiling system was a mess on this mill. I got all new metering valves for it and cleaned out the blocked lines.


                  • #10
                    I just wanted to re-visit this thread. For those that have done the vfd conversion, what size timing belt did you use, what tooth sprockets, and how did you handle belt tensioning? I am at the point of reassembling the drive and need to make some decisions. I scored a 3hp baldor motor that will work for the conversion, I would just need to round up the rest of the parts to do it and make an adapter to mount it.


                    • #11
                      Don't paint yourself into a corner.

                      Dispense with the V/S drive if you must but consider at least two ratios of mechanical reduction between motor and spindle. If you intend to run the spindle at say 3000 RPM sync speed your motor HP will drop in proportion to the frequency as you reduce the setting on the VFD. Assuming a 2 HP motor, your actual delivered spindle power at 300 spindle RPM will be 1/10 of 2 HP or 1/5 HP, about enough to run a 1/2" drill in aluminum or power a 3/8" cutter at half capacity in steel.

                      A lot of guys have done single speed conversions on their turret mills, depending on the VFD alone for speed adjustment. They probably discovered a "dead zone" just above back-gear speeds where the spindle seems to just run out of power. "No torque!" some fool proclaims. Nope. It's the physics of ratio and proportion and mechanical power conversion they don't teach in high school any more.

                      To those who deny preceiving a problem this "dead zone," I submit they have never taken a capacity cut in that RPM range.
                      Last edited by Forrest Addy; 07-12-2014, 03:43 AM.


                      • #12
                        by how much will a vector drive bump up the torque?


                        • #13
                          I used a Goodyear 300H150 timing belt 1.5" wide. and a 2.75" dia pulleys at 1:1 .
                          This made it just about the right tension, for a little adjustment, I made a slight slot in the mounting plate so it could swivel slightly.
                          The ~6.2:1 G.B. takes care of the lower RPM's and I run the 4 pole motor up to 120Hz.
                          Last edited by MaxHeadRoom; 07-12-2014, 11:00 AM.


                          • #14
                            Thanks for the info Max.

                            You are also correct Forest, there are some definite draw backs to a straight VFD conversion with the speed ranges we would like to see on a mill.


                            • #15
                              Originally posted by oxford View Post
                              Thanks for the info Max.

                              there are some definite draw backs to a straight VFD conversion with the speed ranges we would like to see on a mill.
                              I haven't come across any significant problems so far, fortunately the XLO has the advantage of the G.B. for the lower range.