Harrison Horizontal/Vertical Mill Restoration

[Carl Wilson]

More work this evening. Disconnected the windings of the stator from the star configuration. I then soldered them up into delta.

I used glue impregnated heat shrink to insulate the connections, in lieu of the original shellac varnished Cystoflex.

Once the connections were complete I carried out an insulation test at 1000 volts on each winding, to the motor case. All were in excess of 12 mega-ohms.

 

[Seadog]

Once the connections were complete I carried out an insulation test at 1000 volts on each winding, to the motor case. All were in excess of 12 mega-ohms.

They all would, wouldn't they? They're all connected together

 

[Carl Wilson]

Yes. What I meant was on all the windings. This is the reason why I won't be doing you tube videos any time soon.

Sometimes I wonder how I manage to get out of bed.

 

[Carl Wilson]

New bearings have arrived. Great service from bearing boys, usual disclaimer!

 

[Maker]

More work this evening. Disconnected the windings of the stator from the star configuration. I then soldered them up into delta.

I used glue impregnated heat shrink to insulate the connections, in lieu of the original shellac varnished Cystoflex.

View attachment 186153

View attachment 186154

Once the connections were complete I carried out an insulation test at 1000 volts on each winding, to the motor case. All were in excess of 12 mega-ohms.

Will tie wraps be alright holding the windings together? Last one I did I think I tied it with butchers string, I was worried tie wraps could melt, though if the motor's getting that hot there's probably bigger problems I suppose.

 

[Carl Wilson]

I think the tie wraps will be alright. If it gets so hot that they are in danger of melting, then the motor is toast in any case.

 

[Carl Wilson]

Last night I fitted the new rotor bearings.

The rear bearing had a retaining circlip. The original was damaged, and I thought I had a spares kit. We all know what thought did! Fortunately I had a kit of e clips. I used one of those and all was well.

There is enough room in the end bell to accomodate the larger diameter of the e clip.

 

[Carl Wilson]

I was looking at the possibility of making some little threaded plugs to replace the front and rear grease nipples in the motor. They are redundant since fitting shielded bearings.

Investigating the thread form was quite interesting. I initially thought it was M6x1. However, this was not the case. The pitch is 27 tpi, which is normally only found on NPT fittings. The major diameter of the thread is 6.2 mm, so a shade under 1/4" at 0.24. There is also a slight taper to the thread.

In the end I concluded that this is a No 4 Gas thread. My brother has a very interesting, comprehensive book from 1955 that substantiates this idea. Gas threads are BSW form and 27 tpi except for really small diameters.

1/27 = 0.037, which is 0.94 mm. So the 1 mm pitch gauge almost went. That is why I suspected M6 x 1 to start with.

Well...after that circuitous tangent I think I'm probably just going to fit the old nipples back in. It's unlikely that I will forget about the new bearings and try to grease them.

 

[RichardM]

what about the plastic blanking plugs you get on pillow block bearings without the grease nipple?

 

[Carl Wilson]

Nice idea! But I think I'll just refit the original nipples. Won't do any harm. They still had their red plastic covers. Which just shows the bearings had never been greased from new, as they always get lost.

 

[Carl Wilson]

I thought I would show how I fitted the bearings to the rotor shaft. I haven't got a hydraulic press, so if I need to do a job of this type I usually build something up from what I have to hand.

The hydraulic ram shown is from my Clarke enerpac-esque set.

It took 85 bar to press the bearings on.

 

[Carl Wilson]

Yesterday I received a bottle of Methylene Chloride. I'm going to gel it with some vaseline, then use it to strip the paint from the mill.

 

[ronan]

What are those Dunlop bearings like ? I seen them on the bearing boys website and their cheap price had me wondering ? Are they Chinese or something like that ?

 

[Carl Wilson]

They seem fine. Only time will tell, of course. They are going to be a lot better than unshielded bearings running dry, like the ones they are replacing.

 

[minimutly]

Made in EU it said....

 

[Carl Wilson]

Yes made in Latvia.

 

[Carl Wilson]

Substantially rebuilt the motor this evening.

There is now a very marked difference in the feel and sound of the rotor shaft when spun. Noiseless and smooth.

I now need to clean up and fit the junction box parts.

 

[Carl Wilson]

I have been thinking about the motor today. One of the things that crossed my mind was the fact that it doesn't have an external fan.

Given that I'm going to run it from a VFD, I'm just wondering if there will be sufficient throughput of cooling air at lower speeds. I will still be using the gearbox so it won't be running that slowly. Maybe a solution will be to install a separate external fan (like a large computer fan). I don't really want to modify the motor to fit a fan directly to the output shaft.

 

[HughF]

Nice work there Carl. I have the same milling machine that I have just this week converted to a vfd after selling my by rpc.

I have a question... I need to add a core to the wiring harness that runs down from the table feed switch box to add another signal wire to the table vfd I am fitting.

Do you know how to get access to the inside of the column?

I need to get this be blue wire down into the front wiring area of the machine.

 

[Carl Wilson]

Hello Hugh. I will reply to your question later on, and in more detail. I shall also add a photo or two.