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  • Bandsaw blade speeds...

    This almost seems to obvious a question to ask, but I'm not very smart so here goes:

    I am currently working on setting myself up a new (old) Milwaukee-Delta 14" bandsaw. I am gearing it down to run at good metal cutting speeds, but the setup I have will allow me to run from about 50FPS to about 1300FPS with no pulley changes. I'll be posting about my setup elsewhere when I have a bit more time to get my photos together.

    This will be primarily used for cutting metal, but I do cut wood often enough to make it a consideration. Most things I see indicate a 2000-3000 FPS blade speed for wood. Assuming a proper blade, is there any big downside to cutting at say 1300 FPS, aside from the associated slower (not a big deal to me) feed? Not sure I can see one.

    Thoughts??

  • #2
    Hi

    I have a metal cutting band saw with top speed of 300fpm. It was used by a model maker for many years who built live steam locomotives, and all kinds of rolling stock out of wood. This saw was his primary for woodworking, and he produced beautiful work. I do not think you will have issues especially if you can crank 1300fps. Just experiment a bit with tooth count.

    Bob

    Comment


    • #3
      I converted my 14 inch Rockwell ( Delta) years ago and it cuts fine.
      My speed range in 44 FPM, 86 FPM, 163 FPM and 325 FPM .
      I have no problem cutting wood for my needs.
      I have a 18 tooth count blade most times, and it works fine.
      It is not as fast as a 3000 FPM machine , but I would need a 4-6 tooth blade
      for that work.
      What I have done , when I was doing a lot of non-metal work (wood-plastic) was install a
      12 tooth blade that had ALL the teeth reset to twice the kerf . ( from .050 to .080 ~)
      Lots of work to reset the teeth on the blade, but talk about a free cutting blade !

      here is the picture of my direct drive power unit. No slippage ever and only a few seconds to lift the motor and slip the belt for speed changes
      The weight of the motor on its pivot provides all the tension needed on the drive belt.
      Rich

      Comment


      • #4
        Thanks, sort of what I figured. I don't expect I'll be doing much fine woodworking with it, just general utility shop type stuff.

        Besides the ability to feed quickly, what would be the advantage to that high a blade speed? It makes sense in a production time-is-money environment. Bet it takes body parts off quicker, too.

        Appreciate you guys taking the time to reply.

        Rich, I like your gearbox setup. Very neat and nicely done. My saw is likely a cousin to yours, but is a Milwaukee-Delta 14". Nice old solid saw. I'll be posting on it separately soon.

        Thanks again.

        Comment


        • #5
          Originally posted by Rich Carlstedt View Post
          I converted my 14 inch Rockwell ( Delta) years ago and it cuts fine.
          My speed range in 44 FPM, 86 FPM, 163 FPM and 325 FPM .
          I have no problem cutting wood for my needs.
          I have a 18 tooth count blade most times, and it works fine.
          It is not as fast as a 3000 FPM machine , but I would need a 4-6 tooth blade
          for that work.
          What I have done , when I was doing a lot of non-metal work (wood-plastic) was install a
          12 tooth blade that had ALL the teeth reset to twice the kerf . ( from .050 to .080 ~)
          Lots of work to reset the teeth on the blade, but talk about a free cutting blade !

          here is the picture of my direct drive power unit. No slippage ever and only a few seconds to lift the motor and slip the belt for speed changes
          The weight of the motor on its pivot provides all the tension needed on the drive belt.
          Rich

          Nice gearbox setup, any idea what they are originally used in/where to find one? What gear ratio is it?

          Comment


          • #6
            I liked Mr. Carlstedt's so much I made one.
            30:1, from a gate operator.

            Comment


            • #7
              For those of you that don't currently own a bandsaw and you work mostly in metal consider a portaband saw. I have a large Milwaukee and a swag offroad table and it works very well. Without the table I have cut 8" channel and with the table I rough out blocks of metal to greatly reduce machining time. I like the Milwaukee because it is variable speed and has a maximum speed of 425 fpm.

              Comment


              • #8
                Hi
                I am following your threads with interest bing a a band saw nut case
                Can I throw in a few observations I see that your motor is an industrial motor Baldor or Leeson so I guess that the top speed is around 1800 RPM with 10 to 1 gearbox And 1 to 2 pulleys so 5 to 1 over all ratio.
                Consulting with a spread sheet on band saw speed calculation.
                This very near to an Interesting fact that ratio of 3.7 to 1 is that the motor RPM with a 14 inch band wheel is equal to FPM on the blade speed.
                Now apply this to 5 to 1 then 100 RPM on the motor = 73 FPM on the blade speed.
                OR 1800 RPM = 1335 FPM
                Cutting mild steel 120 FPM to about 300 FPM are ballpark figures with 1500 to 3000 FPM for wood and composites.
                I run 3.24 ratio on 14 inch band wheels which gives 125 FPM @ 110 RPM to 1800 RPM = 2000 FPM.
                This works for me and is probably far from ideal.
                Keep posting I am interested in which KB controller you use and the tacho feedback

                Eric
                Last edited by velocette; 01-17-2016, 08:51 PM.

                Comment


                • #9
                  I used a gearbox out of a lawn tractor along with a variable DC motor. It will cut whatever I can jam down its throat.

                  Comment


                  • #10
                    Originally posted by velocette View Post
                    Hi
                    I am following your threads with interest bing a a band saw nut case
                    Can I throw in a few observations I see that your motor is an industrial motor Baldor or Leeson so I guess that the top speed is around 1800 RPM with 10 to 1 gearbox And 1 to pulleys so 5 to 1 over all ratio.
                    Consulting with a spread sheet on band saw speed calculation.
                    This very near to an Interesting fact that ratio of 3.7 to 1 is that the motor RPM with a 14 inch band wheel is equal to FPM on the blade speed.
                    Now apply this to 5 to 1 then 100 RPM on the motor = 73 FPM on the blade speed.
                    OR 1800 RPM = 1335 FPM
                    Cutting mild steel 120 FPM to about 300 FPM are ballpark figures with 1500 to 3000 FPM for wood and composites.
                    I run 3.24 ratio on 14 inch band wheels which gives 125 FPM @ 110 RPM to 1800 RPM = 2000 FPM.
                    This works for me and is probably far from ideal.
                    Keep posting I am interested in which KB controller you use and the tacho feedback

                    Eric
                    Hi Eric,
                    Pretty much all of your deductions are right on. The motor is badged as Boston Gear but is a Baldor motor with a Boston Gear reduction box. A 5:1 would have been ideal of course, but I got it on it's way to the dumpster, so took what I could get. Motor is rated 90Vdc, 1750RPM.

                    The tach I am using is a small Bodine DC motor. It is rated at 1/50HP, 24Vdc. Similar units seem pretty common surplus items sometimes here. I modified the right angle drive so that the tach mounts to the drive and is turned by the worm shaft and thus reads motor speed before the gear box.

                    The controller is a KB electronics KBMM (info here) which has a jumper you cut to allow use with tach generator. Again, something I salvaged from the trash (it was burned out) and repaired. It can directly utilize a 7V/1000RPM feedback signal and can be scaled with just a couple of resistors if your tahco is something different. The manual is available in the link above for more info. These drives seem pretty common on ebay and such.

                    My little Bodine motor gave something very close to the 7V/1000rpm when spun unloaded, so I did not bother with scaling resistors.

                    In operation I can run this down to maybe 15 RPM (at the motor) though I have not fully tested how it works there as of yet.

                    It sounds like you have seen my other thread about the saw, but for any who have not, it is here:

                    http://bbs.homeshopmachinist.net/thr...t-%28again-%29

                    Hope that helps and thanks for chiming in!
                    -Al

                    Comment


                    • #11
                      Thanks for the kind comments on my Rockwell Bandsaw drive.
                      I have a few more pics for you.
                      The motor is 1740 RPM and is a GE 1/3 HP totally enclosed
                      The pulleys are 2,3,4,5 inch step pulleys, so low speed is 2/5 reduction or .4 ( 1740 x .4 = 696 RPM)
                      The gear box is 60 to 1 ( .0167) which makes output at 11.6 RPM
                      The 14 inch tires have a circumference of 3.66 feet or 3.66 x 11.6= 42.5 feet per minute.
                      When I measured it with a wheel counter, I got 44 FPM- probably because the tires are slightly bigger.
                      There is no name on the worm gear box, which I bought for $25 at a salvage store 30 years ago.
                      It is mounted with 2 angled steel pieces that allow for center height adjustment
                      The motor pivot mount is a simple two angle pieces with a center rod inside conduit that is clamped to the motor.
                      The big reduction means the blade never slips , no matter the load.
                      The leather strap ( seen in the first picture above) keeps the motor from having its full weight on the pulleys- not needed and saves bearing and belt wear.





                      here is a handy modification to make to the table.
                      Scribe and stamp the distance from the blade as shown
                      Now when you need to cutoff a piece, there is no guesswork, or measuring tool needed
                      Saves time

                      Rich

                      Last edited by Rich Carlstedt; 01-04-2016, 11:10 PM.

                      Comment


                      • #12
                        Hi Al
                        Thanks for the info on the KB Controller exactly what I needed and plan to drive a DC Tacho with a poly vee belt drive.
                        May need to increase or decrease RPM a little to get 7 volts at 1000 RPM.
                        I like your way of thinking Nut IT Out to make it work and not throw money at it then brag about.
                        Thanks Again

                        Eric

                        Comment


                        • #13
                          You can probably use an O-ring (as a belt) to drive the tach.

                          Comment


                          • #14
                            Originally posted by velocette View Post
                            Hi Al
                            Thanks for the info on the KB Controller exactly what I needed and plan to drive a DC Tacho with a poly vee belt drive.
                            May need to increase or decrease RPM a little to get 7 volts at 1000 RPM.
                            I like your way of thinking Nut IT Out to make it work and not throw money at it then brag about.
                            Thanks Again

                            Eric
                            Sure thing Eric. Glad if it helps some. Make sure to download and take a look at the manual for that controller and study the section about feedback. Note that you are not tied to 7V/1000RPM. If your tach-gen gives you something other than that, you can use just a couple of cheap resistors to change the scaling to the controller to match whatever it is you have. So you can still use direct drive if that is more convenient. Driving it from a belt is fine as well of course. Note too that you don't need anything special to drive the tach as there is practically no mechanical load in it, so even an o-ring as Lakeside says, will do just fine. The rotational drive coupling to my tach it through a 2-56 screw(!).

                            I may at some point switch to poly-vee belts for the main drive if I happen across pulleys and such in workable sizes. It would take a bit less tension on the belts to avoid slippage at low rpm, but that really has not been an issue as of yet. Just another thing I can do in my never ending quest to not leave well enough alone.

                            Comment


                            • #15
                              Originally posted by Rich Carlstedt View Post

                              here is a handy modification to make to the table.
                              Scribe and stamp the distance from the blade as shown
                              Now when you need to cutoff a piece, there is no guesswork, or measuring tool needed
                              Saves time

                              Rich
                              I do like the nice compact way you arranged that drive, Rich. The measurements stamped into the table as reference for quick cuts is really clever. One of those "why didn't I think of that!" things. Nicely done!

                              Comment

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