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Thread: Finished VFD mod to my lathe

  1. #11
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    You know you can buy terminals blocks that fit on the DIN rail? Avoid use wire nuts all together.

    https://www.digikey.com/products/en/...9?k=din%20rail
    https://www.alliedelec.com/product/e...E&gclsrc=aw.ds

  2. #12
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    Quote Originally Posted by reggie_obe View Post
    You know you can buy terminals blocks that fit on the DIN rail? Avoid use wire nuts all together.

    https://www.digikey.com/products/en/...9?k=din%20rail
    https://www.alliedelec.com/product/e...E&gclsrc=aw.ds
    If you look closely, you'll notice that I used quite a few DIN terminal blocks in both cabinets. The bottom cabinet could use some for the grounding wires. The left most cable was too short to feed it directly into terminal blocks, hence why there's wire nuts at the top. Not ideal, could just run all new wires like I did with the front panel, might just do that.

    Sent from my SM-G950U1 using Tapatalk

  3. #13
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    Quote Originally Posted by RB211 View Post
    Swarf will get everywhere but the rear splash guard protects the motor pretty well. The cooling fan on the top of the cabinet is guarded and filtered.
    I'm wondering how high the voltage gets on that resistor, maybe 300v. It's only active for three seconds or less at a time.
    The kind of work I do is never on anything massive, but you know how that goes. This week I had a job that exceeded my Bridgeport's Z height... Maybe in two weeks I'll be turning something that weighs 300 lbs at 2000 rpm and have to hit the E-stop... Probably melt the wires.(which are high quality USA made)

    Sent from my SM-G950U1 using Tapatalk
    Depends if the active device is sinking or sourcing. If sinking (i.e. the "switch" is to the common) the full dc voltage is present whether braking or not.

  4. #14
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    Just piling on, I know, but the terminals of the resistor are normally hot with the bus voltage. You want that covered up.

    The resistor ventilation thru the center will not be an issue in stop duty. the resistor is commonly mounted just as you have done. Plus, there is a duty cycle setting in the VFD, which is normally co-ordinated with the resistor wattage according to a formula that the instructions ought to have.

    The braking resistors are often overloaded by factors up to 10 or more. it is the duty cycle that determines heating. A 250 watt resistor, if made for the purpose, can take 2500 watts 10% of the time and that equals 250 watts average. The only caveat is that the 10% cannot exceed the "integration time" that the mass of the resistor provides. So on time 5 seconds out of 50 is likely to be OK, where 5 minutes out of 50 would not, because the resistor would cook in 5 min on time, where it would not in 5 seconds on time. But stopping a lathe etc does not take 5 minutes, and usually not 5 sec even.

    You do need a resistor of a type made to take excess current. Not every one of them is.
    Last edited by J Tiers; 06-12-2019 at 11:07 PM.
    1601

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    Hashim Khan

  5. #15

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    The first photo looks just like my lathe, which is the Prince 13x40 from Jessey in Taiwan. Is yours the same? How do you like it?

  6. #16
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    Quote Originally Posted by rohamm View Post
    The first photo looks just like my lathe, which is the Prince 13x40 from Jessey in Taiwan. Is yours the same? How do you like it?
    It is a Taiwan lathe, sold by Precision Mathews. It's identical to his GT1340, just differs in size and hardened gears. You probably have the GT1340. I really like it so far, haven't cut metal with it yet though.


    Sent from my SM-G950U1 using Tapatalk

  7. #17
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    Quote Originally Posted by RB211 View Post
    Swarf will get everywhere but the rear splash guard protects the motor pretty well. The cooling fan on the top of the cabinet is guarded and filtered.
    I'm wondering how high the voltage gets on that resistor, maybe 300v. It's only active for three seconds or less at a time.
    The kind of work I do is never on anything massive, but you know how that goes. This week I had a job that exceeded my Bridgeport's Z height... Maybe in two weeks I'll be turning something that weighs 300 lbs at 2000 rpm and have to hit the E-stop... Probably melt the wires.(which are high quality USA made)

    Sent from my SM-G950U1 using Tapatalk
    You would do probably OK even if you mount the resistor inside the cabinet as it has even a cooling fan.
    Brake resistor on lathe needs to handle pretty low power on average if you dont go crazy starting and stopping it every half second.

  8. #18
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    Quote Originally Posted by RB211 View Post
    Swarf will get everywhere but the rear splash guard protects the motor pretty well.
    I had long swarf get into the motor fan of a similar Jet lathe. It also got into the centrifugal switch, which was part of the fan. Ended up putting a screen over the inlet. That lathe did not have a backsplash.

  9. #19
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    Quote Originally Posted by reggie_obe View Post
    You know you can buy terminals blocks that fit on the DIN rail? Avoid use wire nuts all together.
    Quote Originally Posted by RB211 View Post
    If you look closely, you'll notice that I used quite a few DIN terminal blocks in both cabinets. The bottom cabinet could use some for the grounding wires. The left most cable was too short to feed it directly into terminal blocks, hence why there's wire nuts at the top. Not ideal, could just run all new wires like I did with the front panel, might just do that.

    Sent from my SM-G950U1 using Tapatalk
    Is that skinny terminal block at the bottom of the top cabinet DIN rail mount also? I missed that. Nice job!

  10. #20
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    Mar 2015
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    Quote Originally Posted by reggie_obe View Post
    Is that skinny terminal block at the bottom of the top cabinet DIN rail mount also? I missed that. Nice job!
    No, it is however the only item in that cabinet that is original and untouched. I'm bummed that the new VFD isn't DIN mountable like the old one. I'm really digging that stuff.

    Sent from my SM-G950U1 using Tapatalk

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