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  1. #91
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    Quote Originally Posted by simonl View Post
    Hi all,

    I'm continually looking looking for options when it comes to using a 3 HP 220V DC motor I have. I have attached pic of it before. Anyway I have been looking for a cost effective way of running it at or close to it's rating or at least 2000W. Trouble is there is not a lot out there. I was wondering if you could use two of these:
    AC110/220V Input 2A/3A/4A/5A 1000W SCR DC Motor Speed Controller Driver Adjuster | eBay

    and just parallel them with some inline high powered rectifying diodes so that they will not interfere with each other. The pots could be combined using a a double gang pot.

    Is this a viable alternative?

    Simon
    Hi Simon,

    Have you looked at this?

    http://www.kbelectronics.com/data_sheets/kbcc.pdf

    It's not full 220 volt but should run the motor within the maximum /recommended 60/70% torque/speed range which would be within 200 v DC .

    Eg. KB Electronics DC Motor Speed Controller Model KBRG-225D | eBay

    Cheers

    Rob

  2. #92
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    Ueee is offline Blacksmith, Cabinetmaker, Machinist, Messmaker
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    I spent this arvo making a spindle nose plug gauge, just so i could try out threading with the DC motor. I started with the lathe in bottom gear, 6-1, but once the cut started to get bigger the flat belt started to slip. So i put the lathe in back gear, giving me something like 25-1 ratio. At first i used the speed pot to turn on and stop the lathe, but i ended up just setting the speed (100rpm) and using the fwd/off/rev switch. Even with an 8tpi thread i was able to stop the lathe in a 1/8" groove every time. I also accidentally switched from forwards into reverse with the spindle still turning, and the controller survived......gulp.... The best bit was when i came to part the gauge off. Left hand feeding, right hand on the speed pot....as i fed i just slowly ramped the speed up. I have never had such nice shavings consistently through a parting cut before.

    I fished out my nichrome wire today looking at making a 5ohm resistor. The wire i have is pretty fine and i'm worried that the short length i would need (about 400mm) won't be enough to dissipate the heat. So i have ordered some .65mm wire, i will need just over 2m of it so heat should not be a problem. It has also occurred to me though that i can't solder the stuff....i wonder how many times someones found that out the hard way?

    Rob, the V belt is the one that is flapping, the flat belt is very smooth but lacks the drive power of the V belt.
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  3. #93
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    Quote Originally Posted by nearnexus View Post
    Hi Simon,

    Have you looked at this?

    http://www.kbelectronics.com/data_sheets/kbcc.pdf

    It's not full 220 volt but should run the motor within the maximum /recommended 60/70% torque/speed range which would be within 200 v DC .

    Eg. KB Electronics DC Motor Speed Controller Model KBRG-225D | eBay

    Cheers

    Rob
    Hi Rob,

    you guys give the DC motor option a good wrap! That 3 HP motor is on ebay and is all but sold with 1 bid. I figured it's probably a little too big for my lathe so I will just keep an eye out for a smaller 2 - 2.5HP motors. Thanks for the link to that controller. I'm thinking of bidding on it.

    Cheers,

    Simon

  4. #94
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    Quote Originally Posted by simonl View Post
    Hi Rob,

    you guys give the DC motor option a good wrap! That 3 HP motor is on ebay and is all but sold with 1 bid. I figured it's probably a little too big for my lathe so I will just keep an eye out for a smaller 2 - 2.5HP motors. Thanks for the link to that controller. I'm thinking of bidding on it.

    Cheers,

    Simon
    I actually contacted the guy as I am also a bit interested as that model has armature switching built into the circuit board - so no back EMF problem.

    The downside is that regenerative controllers make the motor run hotter - according to a KBE write up.

    I wasn't sure if he posted (unclear in write up), but he does and it's about a 3 kg parcel.

    Anyway, see how the bidding goes. They are a much more expensive unit, so it may turn out to be considerably more than the current bid belies

    Ewan if you have belt flap you can probably cure it by running a sping loaded tensioner pulley (use a large roller bearing) on the flat side.

    Cheers

    Rob

    so .

  5. #95
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    Quote Originally Posted by nearnexus View Post
    I actually contacted the guy as I am also a bit interested as that model has armature switching built into the circuit board - so no back EMF problem.

    The downside is that regenerative controllers make the motor run hotter - according to a KBE write up.

    I wasn't sure if he posted (unclear in write up), but he does and it's about a 3 kg parcel.

    Anyway, see how the bidding goes. They are a much more expensive unit, so it may turn out to be considerably more than the current bid belies

    Ewan if you have belt flap you can probably cure it by running a sping loaded tensioner pulley (use a large roller bearing) on the flat side.

    Cheers

    Rob

    so .
    Thanks Rob,

    I'm watching it. As for the belt flap, I agree, a tensioner system similar to the tensioner pulley on a timing belt will work a treat.

    Simon

  6. #96
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    Hi all,

    I had a good play around with the maximum speed setting on the controller today and really put the lathe under some serious load and ran it for an extended period.

    The recommended 60 - 70% of rated motor speed maximum is there for a good reason. Once you go beyond that ratio temperatures start rising quite severely.

    You definitely need a half decent air cooling system, even within the recommended speed range. The PC fans work well and it's definitely a bonus that you can cool with the motor off - temperatures come down very quickly.

    You also definitely need at least two ratios, high and low to gear the motor for the required tasks.

    For milling the high ratio currently takes the spindle to 1800 rpm, and for threading etc the low range takes it to 500 rpm, so that seems quite useful for the ability/torque of the motor.

    I have the option of sleeving the original motor pulley and getting back all my original ratios, effectively halving the low speed and doubling the high speed, but I don't think that's necessary.

    Temperature wise the controller does not even get warm, so a heat sink is unnecessary with this HP motor (1.5).

    Overall it's an interesting project.

    Cheers all

    Rob

  7. #97
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    I found the temp goes up pretty quickly once you load the motor up. The only part of the controller that gets hot is a large black resister on the upper left of the board. The SCR's don't seem to get hot at all. The only other odd thing has been every time i have gone to turn the lathe on when it is cold is i get really bad arcing if i go straight to a high speed. Its like i have to warm her up slowly...

    I have some rollers from one of the treadmills that will make perfect belt tensioners. I am still yet to fit new pulleys to get my final ratios so i will wait to see what it is like with the new pulleys first.
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  8. #98
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    I think i have her nearly done now, though i might still play with the pulley sizes a bit. I have 5-1 and 5-2 to the countershaft and 1-1 and 2-1 to the spindle.

    I was machining some cast today, a new backplate, and i blew the 10a DC fuse. What size fuse have you got on the DC side Rob?

    I received my new switched linear pots today from hong kong......but they are not switched. Serves me right for being cheap...but the sender is sending me a new pair, and promises that they will be the right ones...fingers, toes and eyes crossed. I'm going to have to put another trimpot in line with the speed pot so i can adjust the top speed down, it is still too fast (like 4.5K motor speed) with the max speed turned right down, and the load voltage at 136v. What the?
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  9. #99
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    Hi Ewan,

    I've got a 10 amp on the DC side and had no problems.

    15amp on the AC. Both are slightly higher than recommended.

    I was doing some work with the tool post grinder yesterday and this twist the knob to vary the speed down to almost nothing is just awesome. I'm wrapped

    Couldn't be happier with the way mine turned out.

    One of the five controllers I brought in from the states has a blown diode rectifier in it, so I'm currently sourcing a replacement. Looks like they snuck one dud in with the batch of old new units

    Been onto a guy in the UK on these and looks like an easy fix. Apparently when they go "pop" its D14 that lets go most times. Seems like there are quite a few revisions on this board.

    I see that the regenerative KBRG-225 board on Ebay went for about $110 - which is about what I expected.

    Cheers

    Rob.

  10. #100
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    Well guys I can report that the DC lathe completion is finished and turned out pretty neatly.

    It was a lot of work - and my learning curve went up by about 500%.

    But it was worth it.

    I've put up a few pictures for those contemplating going in this direction - Chinese style

    The three belt ratios give approximate speeds of 0 - 500, 0 - 1500, 0 - 1800 with the controller set at 60% maximum speed.

    One photo shows the f/r switch in the middle position, which runs the fans only.

    The potentiometer has replaced the original f/r switch next to the on/off master kill switch. The original magnetic actuator/isolator function has been retained.

    Cheers

    Rob
    Attached Images Attached Images

  11. #101
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    Job well done Rob.
    Splash gaurd by brown built?
    What are gears under the lathe for?

    Stuart

  12. #102
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    Good work Rob

    I'm still going, have had some more idea's.....
    Still waiting on the wire to make a resistor, although the more i use her the more i like the current stopping speed.
    I sorted out the max motor speed today by adding a second trimpot as a voltage divider to feed the speed pot. My speeds are a little more conservative than yours Rob, with a max motor speed of 3k (62.5% of the motors top speed) I have 30-300 rpm, 60-600, and 125-1250. Plus of course i have a 9-1 backgear if i really need some nice slow torque.....

    After internally threading a new backplate (very comfortably at 200rpm) i have thought that rather than the speed pot switch, a NC switch on my saddle stop that cuts the power to the forwards control could be very handy, especially for blind threading. This way the lathe should stop consistently when the saddle triggers the switch, but i will still be able to switch to reverse with the switch triggered (i have no thread dial so i always reverse the lathe when threading).
    1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.

  13. #103
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    Hi all,

    Yes, splash guard by BrownBuilt I went for quality.

    The gears under the lathe are a 2:1 reduction gearbox I made up to drop the lowest speed to 70 RPM with the original pulley setup.

    I can still use it with the new setup, so I just left it there. It's made out of some timing gears from a stationary engine.

    I"m still undecided whether to refit the original motor pulley - easy job, but until I turn up some real big stuff I won't be sure exactly how much grunt I really have at the moment.

    Good idea with the saddle switch Ewan. That should work well. This jobs been more thinking than doing most of the time.

    Anyway that's it for now - I must get on with some house repairs as this has all gone on far too long.

    But I will still be thinkin

    Cheers all

    Rob

  14. #104
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    Morning Gents,
    One of my works in progress that has not seen a lot of progress recently is a remote start/stop switch for the lathe, it will be mounted to the bottom of the apron and should be a little quicker to get to during those "oh crap" moments. The switch is a Schneider 2 position momentary action joystick, as supplied these have 2 N/O contacts , but the contacts are modular and readily available in N/C ,the contacts are stackable should you want to add extra functions (a coolant pump comes to mind).
    Regards,
    Martinss1.JPG

  15. #105
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    Quote Originally Posted by nearnexus View Post
    Well guys I can report that the DC lathe completion is finished and turned out pretty neatly.

    It was a lot of work - and my learning curve went up by about 500%.

    But it was worth it.

    I've put up a few pictures for those contemplating going in this direction - Chinese style

    The three belt ratios give approximate speeds of 0 - 500, 0 - 1500, 0 - 1800 with the controller set at 60% maximum speed.

    One photo shows the f/r switch in the middle position, which runs the fans only.

    The potentiometer has replaced the original f/r switch next to the on/off master kill switch. The original magnetic actuator/isolator function has been retained.

    Cheers

    Rob
    Hi Rob,

    Nice job, very clean and neat, looks well thought out and nicely implemented.

    Regards
    Ray

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