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small vertical mill speed range recomendation

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  • #16
    Update
    I got a used 1/2hp 3 phase motor from a forsale newsgroup, it wasn't local, 700km away, but the seller was very helpful and forwarded it by courier, for a grand total of $60.Today I received the single to 3 phase converter from amazon $110 and tested the whole package together. Yahooooo, it worked like a charm. Now i just got to make an adapter plate for the motor and I will be all set. I love the WorldWideWeb , I was able to find the motor, controller and great advice.
    Thank you

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    • #17
      Have you checked the spindle diameter of the motor? I had to bore out the pulley for the new 1hp motor and also had to press on a strengthening ring as the pully was thin walled at that end. Click image for larger version

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      • #18
        6130 sounds way to fast for one of those mills, has someone changed the pulleys to make it run faster. Can you put different pulleys on it to lower the speeds to what you want.
        The shortest distance between two points is a circle of infinite diameter.

        Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

        Southwestern Ontario. Canada

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        • #19
          These little Tom Senior vertical heads are much too small to give any leeway with pulley sizes.
          When I changed the museum's one from MT2 to R8, I fitted a 6 pole 1hp three phase motor with a VFD set from 25-75 Hz, which gives a top speed of 2900rpm. On the lowest pulley ratio (only 4 on this one) and lowest motor speed, about 174rpm.





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          Last edited by old mart; 09-14-2020, 04:22 PM.

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          • #20
            I was lucky the motor spindle is a matching fit. I like the way you reinforced that pulley, I will put that technique tip in my tool box and the R8 upgrade would be nice.
            Last edited by fixerup; 09-15-2020, 08:11 AM. Reason: grammar

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            • #21
              When you say small, I think of small end mills, 1/8th and what not. Spindle speeds approaching 10,000 RPM would be nice. Now did you mean medium sized mills? Guess this is all relative.
              10,000 RPM though with Aluminum is best done with CNC where you can dial in the speeds and feeds appropriately or else you will get instant chip welding.

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              • #22
                What speed is your 1/2hp motor? I made an adaptor plate for the motor out of 1/2" or 12mm aluminium plate, which was thinner, but stronger than the original cast one. The difference in thickness will influence the pulley alignment possibly.
                The pulley ratios are 2.07:1 for top speed, and 1:2.68 for bottom speed. The ratios between max and min are the same whether there are 4 or 5 pulley ratios.
                Last edited by old mart; 09-15-2020, 01:33 PM.

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                • #23
                  The motor speed of the 1/2hp is 1725rpm.With the VFD I hope to get a good selection of speeds in the low range. The new motor had 4 equally spaced mounting screw, I got excited and thought it would bolt on directly to the original motor plate, but no. It is on a slightly larger bolt circle. No problem I will make the new plate. I did compare the motors shaft dia and length and they are both the same, so i will make the plate 1/2" thick just like the original and the pulley should line up just like before.

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                  • #24
                    That motor should give you 3570rpm at 50 Hz in top gear, and if you reduce the frequency to 25 Hz in the lowest gear, 321rpm. Lowering the frequency further can be done, but the torque drops off and prolonged use might cause overheating as the motor fan wont be so effective.
                    There is plenty of info on these Tom Seniors on the UK forum, model engineer.

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                    • #25
                      Have you looked into treadmill motors with their speed controls?

                      Also I would look into a 3 phase motor from a surplus supplier.
                      Paul A.
                      SE Texas

                      Make it fit.
                      You can't win and there IS a penalty for trying!

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