Harrison Horizontal/Vertical Mill Restoration

[scottmk1]

I agree with Maker, it's probably best just to make sure there is no burrs on it and fit the new bearing as welding it is going to cause more issues

 

[Robbair]

I have just caught on to your thread and it is great inspiration. I have a sadly neglected manual Elliot mill that I must get to grips with at some point although I have to put the front wall on the workshop first. Sadly it probably won't be this winter, there is too much else on the list. I am interested that you go to the trouble of rewiring the motors though, as I don't have 3 phase in the new workshop I had thought to use VFD's instead, either a large one as a single point solution or individual ones as machines get overhauled and brought back into service..... is there much advantage in reworking the motors or would a 240v input 440v output VFD be just as easy?

 

[RichardM]

For future reference, I have found on motorbike steering stem bottom bearings I have removed, if you put a cut as diagonally as possible in the inner race then put a screwdriver blade in and twist it the remainder cracks and it is an easy twist the screwdriver to open the inner and take it off.

I wouldn't bother welding it up - bigger can of worms!

 

[Carl Wilson]

Thanks chaps for the encouragement. Richard - I did look at grinding the inner race diagonally but I didn't want to damage the washer or the fan. In retrospect the washer could have been sacrificed - I could easily have turned up a replacement. You live and learn.

Rob - I've never actually considered getting a 240 to 440 vfd. I'd always assumed they were more expensive. As I've gone down this road now though I'm going to stay on it. Whilst I'm certainly no expert, I think that having a single vfd to power everything is not generally encouraged. They don't like having their outputs switched, and ideally you need to set the parameters to the specific motor it is powering. So with a lot of different machines you'd need to have a menu of parameters. Maybe not ideal. I hope you get your workshop sorted soon. I look forward to seeing the work you do on your Elliot Mill.

Thanks Scott for the encouraging words of wisdom. I'm not going to weld it up. As everyone has said, more trouble than it is worth.

 

[Carl Wilson]

Another paint stripping experiment. Trying Sodium Hydroxide. I bought a bottle of Oven Pride oven cleaner today. This is Sodium Hydroxide along with surfactants. I've just put it on the casing of the Gryphon motor, which is covered in the God forsaken Hammerite.

Let's see what happens. Obviously I will keep it away from Aluminium or yellow metals as Sodium Hydroxide corrodes them.

 

[Carl Wilson]

Just done a quick check of the motor. The sodium hydroxide is definitely lifting the hammerite.

 

[Maker]

Let's see what happens. Obviously I will keep it away from Aluminium or yellow metals as Sodium Hydroxide corrodes them.

I dunked the aluminium ends of a motor in sodium hydroxide, it bubbled and fizzed a lot but in less than ten minutes all the paint was shifted and the surface seems fine and the bearing bores are still a nice snug fit. It was a tense ten minutes though with lots of fishing it out to check the progress.

 

[Carl Wilson]

Ladies and Gentlemen, we have a winner.

I took these photos this morning after the motor case and end plate had been left overnight with the sodium hydroxide on. Then I scraped the residue off this morning, very easily. Then a wash in equipment cleaner to remove any traces of caustic, then a touch with the wire wheel.

The scraping needed was very light indeed. And the wire wheel was purely to buff the parts. I don't want to make too much play of the mechanical means - it was the sodium hydroxide that removed the hammerite, of that there is no question.

I believe this to be a viable method of paint removal for the rest of the project, provided the caustic is kept away from Aluminium or yellow metals. The green coating is some sort of original etch primer which I don't believe will give me any issues.

Thanks are due to @Dennis Aspö for his use of sodium hydroxide, which gave me the idea to try oven cleaner. The experiment has been an unqualified success.

And, right on cue, this turned up while I was in the shop:-

 

[slim_boy_fat]

Thanks are due to @Dennis Aspö for his use of sodium hydroxide, which gave me the idea to try oven cleaner. The experiment has been an unqualified success.

That is impressive!

 

[Carl Wilson]

Yes it is. If you look carefully you'll see the body of the motor case is turned. So quite smooth. I think more scraping would have been needed on a rougher substrate, like say cast iron. That said the sodium hydroxide would still destroy the hammerite.

 

[RichardM]

I could be wrong, but UK wise I don't think you can get 240v single phase input to 415v three phase output vfds.

 

[ronan]

I could be wrong, but UK wise I don't think you can get 240v single phase input to 440v three phase output vfds.

I think you can, but they are much more expensive than the usual 240v in 240v out on three phases.

 

[Carl Wilson]

You can get 240 - 415 volt single to 3 phase vfd's but as mentioned they are more costly.

I'm quite happy converting the 415 volt motors to delta and running them from the 240 volt 3 phase variety. Cost is a factor but my main reason is uniformity.

 

[Carl Wilson]

Started the process of rewiring the Gryphon motor.

Here is the star point.

It's a case of carefully cutting away the varnished lacing cord to expose the connections. I will megger each winding individually before reconnecting them in delta.

 

[Carl Wilson]

Just finished reconfiguring the stator windings to delta. All that remains is to solder the flying leads on and insulate them. For that I'll be using glue heatshrink, as I did on the main motor.

I meggered the windings to the case and to each other after disconnecting them from star. All was good. Continuity check resistance of each is about 62 ohms.

 

[Carl Wilson]

Delta conversion completed. I put some glue heatshrink around the conductors where they leave the casing. Just in case they rub against the penetrator.

 

[Carl Wilson]

There has been a bit of a dearth of posts recently on the mill restoration. This is owing to my working through in Aberdeen for a couple of weeks. I'm back home now so I will be getting on with things in the shop.

I bought a new bandsaw - an Aldi one, and I'm selling my big SIP bandsaw to a friend, which will free up some space. The next job on the mill will be fitting new bearings to the feed motor rotor and then priming and painting the casing and end bell.

 

[Carl Wilson]

This evening I fitted the new bearings to the Gryphon rotor. They are 6202 2RS. The rear bearing got a new circlip. I've also ordered a new oil seal for the output shaft. The size was 29mm OD x 15mm ID x 7mm width. I had to make a simple tool by boring out a piece of aluminium tube in order to knock on the front bearing.

I've also started masking up the motor casing, end bell and gearbox casting.

 

[Carl Wilson]

Some more work on the Gryphon motor this morning. All of the assembly hardware is BA. The four tie rods holding the motor together are 2BA and the two screws holding the rear bearing grease cap in place are 4BA.

I cleaned up the threads on all these parts. There are two different types of special 2BA nut in the tie rods, slotted at the front or output shaft end and hex at the rear end.

Curiously, there was a bit of surface corrosion on the hardware. I say curiously as there were no signs of rust anywhere else in the motor.

I appreciate that posting pictures like this might appear trivial. That said, I'm trying to include as much information on the Gryphon motor as I can, since during my research for the rebuild I could find none.

 

[minimutly]

I've been fighting with an ancient 240 to 415 inverter - was used on an atlas copco vtwin compressor and my miller. Ultimately it won, I fixed it numerous times and it kept blowing the gtos until I ran out of them - I scrapped it. The latest one (another skip find), died the other week, tripping out on overcurrent.
So I'm in between trying to fault find on it, modifying a 415/415 one or buying a new 240/240 one and delta wiring the motor.
Good, inspiring thread.