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  1. #21
    I've just wired the coolant pump up - took the end plate off the pump and changed it to Delta. To test it I've taken the main motor off the VFD and just connected the coolant pump without changing any settings on the VFD. It works fine, although there's not enough coolant in the tank to actually pump it round at the moment. I'll have to get some, again I'm not sure which to get and where.

    The question that remains is if I'm OK to run the main motor and coolant pump on the VFD at the same time. The pump is 2 pole, and the main motor 4 pole, however the pump worked with the VFD still set to 4 pole. I've searched on other forums and people have done it.

    The pump only draws 0.22A, but with a 3Hp motor on the VFD I'm right on the limit - especially with it being in delta(?) ... the problem is when the main motor has a big load on it is when I want to be running the coolant! If I do put the pump on the VFD I'll put a relay and switch in so that you can only connect the pump when the VFD is off.

    This implies it is ok:

    http://web.applied.com/base.cfm?page_id=3124#q5
    Last edited by Jonathan; 21-04-2011 at 04:22 PM.

  2. #22
    Looks like a good sturdy machine. Those old colchesters are capable of hard work. Is the bed hard or soft? Some of the roundheads had soft beds. Watch out for the gamet bearings. If you have to get new ones you may have to dig fairly deep!

    Even if the lathe is old it does not mean it has had it. Just look at the old DSGs and Halifax lathe in the mech eng toolroom at the uni!

    I am sure you will enjoy taking cuts with a machine with a bit of meat. The saddle also has T slots which are great for boring jobs.

  3. #23
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 9 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,834. Received thanks 192 times, giving thanks to others 5 times.
    The coolant pump only uses a fraction of the power the spindle will use, so I personally wouldn't say it's going to be a major issue in terms of doing anything bad to the VFD, especially considering the coolant pump isn't likely to be running near it's rated power.
    However, what if you want to use the VFD to change the speed of the spindle?

    Other option is a simple static phase converter using a capacitor to power the coolant pump.

  4. #24
    Quote Originally Posted by Andrew Wilding View Post
    Looks like a good sturdy machine. Those old colchesters are capable of hard work. Is the bed hard or soft? Some of the roundheads had soft beds.
    There's a sign on the bed saying "Induction Hardened Bed"

    Quote Originally Posted by Andrew Wilding View Post
    Watch out for the gamet bearings. If you have to get new ones you may have to dig fairly deep!
    Are they not a standard size then? They seem fine at the moment - if I disengauge the motor and spin the spindle by hand it feels very nice and smooth. Having said that the headstock did get a bit warm near the chuck end when I ran it at 1200rpm for a while. I'm not sure if that's normal.

    Quote Originally Posted by Andrew Wilding View Post
    Just look at the old DSGs and Halifax lathe in the mech eng toolroom at the uni!
    I would if I was allowed in. I asked about if I could use the machines and they said only if I do the training (health and safety reasons), which I don't mind though I doubt it would be more than I'd done at school. Anyway, it never happened so the nearest I've got it watching standing on the balconies!

    Quote Originally Posted by Andrew Wilding View Post
    I am sure you will enjoy taking cuts with a machine with a bit of meat. The saddle also has T slots which are great for boring jobs.
    Definately - at school they have two M300's and one M250 which I used a lot. I never thought I'd own a similar lathe. There was also a bigger lathe - over 50 years old I think and it was better than the Harrison, except I was about the only one to use it because it had imperial dials. Now sold to make space for laser cutter...waste in my opinion!

    Anyway I'm going a bit off topic...

    Just to test I faced 50mm MS & aluminium bar and chamfered the steel, here's the result:

    Click image for larger version. 

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    Not the most interesting test but it got a nice shiny finish. Happy!

    Quote Originally Posted by m_c View Post
    The coolant pump only uses a fraction of the power the spindle will use, so I personally wouldn't say it's going to be a major issue in terms of doing anything bad to the VFD, especially considering the coolant pump isn't likely to be running near it's rated power.
    However, what if you want to use the VFD to change the speed of the spindle?
    I reckon I'll try them together tomorrow. Why would I want to change the spindle speed with the VFD significantly? It's easy to change the gears and keep the motor at full speed which will surely get more torque. If I want a speed between the standard ones I won't have to reduce the frequency much.

    At the moment I've only ran the motors at 50Hz, however they both say 50/60Hz. I'm going to test the actual rpm of the spindle tomorrow.
    Last edited by Jonathan; 21-04-2011 at 11:32 PM.

  5. #25
    I've found some standard oil for a better price:

    http://cgi.ebay.co.uk/Smith-Allan-T3...item3a6147458c

    T68 is the same price from that seller and as far as I can see T## is equivalent to ISO## oil. 10W oil is equivalent to ISO32, and 20W equivalent to ISO68 according to this site:

    http://www.engineeringtoolbox.com/is...il-d_1207.html

    I'm not sure if that means, for instance, 10W40 as used in car engines is suitable. It's widely available (Halfords, B&Q etc).
    Last edited by Jonathan; 22-04-2011 at 01:20 PM.

  6. #26
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 9 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,834. Received thanks 192 times, giving thanks to others 5 times.
    Mutli-viscosity oils such as 10W40 have viscosity modifiers so the viscosity remains more constant over temperature change.
    A 10W40 oil acts like a SAE10 oil at 25degC, and a SAE40 oil at 65degC (at least I think that's what the temps are, but they're maybe 5deg of!).

    Engine oils also have a lot more additives and detergents (with the exception of the more specialist SAE oils aimed at small engines/classic engines), which there is a possibility may cause issues with some seal types, and the detergents can dislodge drit/grime that would otherwise be sitting causing no problems.

    Hydraulic oil on the other hand, is pretty much one of the purist oils you can get, with minimal additives, and certainly no viscosity modifiers.

  7. #27
    Quote Originally Posted by m_c View Post
    ...10W40 oil acts like a SAE10 oil at 25degC, and a SAE40 oil at 65degC...
    How hot should the headstock get - not 65C? At the moment it's a little warm, but not excessively.

    Quote Originally Posted by m_c View Post
    Engine oils also have a lot more additives and detergents (with the exception of the more specialist SAE oils aimed at small engines/classic engines), which there is a possibility may cause issues with some seal types, and the detergents can dislodge drit/grime that would otherwise be sitting causing no problems.
    I've searched on other forums and it looks like other people have used it. Some of the additives might be beneficial...

    I'll get the hydraulic oils for 13.71 off eBay to be safe. It doesn't say in the manual how much is required, but I should think 5L of each is plenty.

  8. #28
    Now the gearbox oil is sorted time to decide on cutting fluid.
    I think this is suitable:

    http://www.toolbox.co.uk/rocol-roc35...sol-5401-96554

    I'm wary of using anything that's diluted with water. How good are the rust inhibitors? I don't want to risk the lathe bed rusting.

  9. #29
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 9 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,834. Received thanks 192 times, giving thanks to others 5 times.
    Biggest issue with soluble oils is them going off, but I've never had any problems with my milling machine and I've never changed the coolant since getting it several years ago.

    Provided you lube the lathe with slideway oil, any coolant left on the bed will evaporate the water out before anything happens to the metal.
    Only place I ever get rust on the milling machine is in any chips that have been left lying for a while, which is more likely to be caused by the dampness in the shed rather the coolant. The same applies to the bandsaw, which never sees any oil.

  10. #30
    That's encouraging, thanks. I have a dehumidifier in the workshop so that should help evaporate the water quickly. Do you think the coolant I linked to is a good, choice / what did you use?

    There are so many to choose from:

    http://www.toolbox.co.uk/rocol-roc51...ign=GoogleBase

    http://www.rdgtools.co.uk/acatalog/C..._and_oils.html

    http://www.ccw-tools.com/prodtype.as...story=category

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