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:
Last edited by Jonathan; 21-04-2011 at 03:22 PM.
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.
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.
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:
Not the most interesting test but it got a nice shiny finish. Happy!
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 10:32 PM.
I've found some standard oil for a better price:
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:
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 12:20 PM.
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.
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.
Now the gearbox oil is sorted time to decide on cutting fluid.
I think this is suitable:
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.
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.
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:
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