A normal day at the office

[John S.]

Still owe the board some shop photos which I will get round to but thought I'd show you a normal day or at least part of one.

Monday morning so as usual there is a job waiting on the yard outside the door when I get started.
As usual no instruction but there are two white marks on two diameters and quick check shows they are both undersize.

   

left hand one is 30mm for a bearing, right hand one is 25mm plus 0.01 for a brake hub.

So gob some snot on with the MiG and wait for it to dry.

   

Support with a steady and single point the centre hole in the end because they always bend a bit and turn down to finished sizes. Then replace the 8mm keyway.

   

Sorry for the crap photo must have tripped over something !

In the mean while a coupling I had been primed for on Friday appears, it's bored 70mm and keyed but is going onto a new motor at 65mm.
Always easier to go from 65 to 70 but going the other way requires boring out sleeving and pegging, then reboring and a new keyway cutting.

Or you could do as I do and cheat and fit a taper lock coupling. Hunt round on the CAD system and find the taperlock drawing and print out full size.

   

Hub, coupling and drawing.
Cut out on pre drawn 70mm circle and attach to hub with high precision sticky tape. Whack three mounting holes.

   

Drill two holes all the way thru and tap 5/8" Whit to suit supplied screws.
Drill last hole 5/8" clearance 1" deep for the extraction hole.

   

Stick in the lathe and bore out to the small taper end diameter, do this because I can use power feed and then do the last taper cut with the top slide set over to 4 degrees to open out to the final diameter.

   

Hole opened out at 4 degrees taper.


   

Ignore the rusty holes at 3 o,clock and 9 o,clock, they were already in but you see how the tapped holes have been half removes so the screws pushes the insert into the taper and causes it to grip the shaft.

Finished job.

   

I like taperlocks as they will take up slight wear on shafts and they really grip

Next job before dinner was a typical bodge.
Older Wadkin routers used to have 1 1/4" shafts but tooling for these is hard to find and inserted tooling is next to impossible, all modern tooling being on 30mm so Wadkins in their infinite wisdom just turned the 1 1/4" shafts down to 30mm but the 1 1/4" x 12 tpi thread then becomes half a thread.

No good them making a new shaft as their equipment of the era was all imperial and they couldn't screwcut metric [ or wouldn't ]

So they just cleaned the thread up and made a 30mm x 12 tpi nut to suit.

There are loads of these machines out there with double standard fittings, problem is Wadkin has gone to the wall and they never made any spare nuts anyway.

So cut the shaft down to 30mm and it shows the 1/2 thread that's left.

   

Make a new nut from a piece of hex bar, again bad pic.

   

Then pick the old thread up and cut a new thread to suit the nut.

   

And that's a typical morning, time for me cheese and pickle

[PixMan]

Nice work John! In my early days I did a lot of repair and overhaul work for couplings like that. My employer was a maker of plastics extruders and downstream filtration and process equipment, though he also bought & sold a lot of used machinery related to that business. I've seen those taper lock shaft couplings on so tight and permanent that the only way they came off was to machine them off or even use a cutting torch.

Funny thing about the 12 threads per inch threads, we get a lot of that on this side of the pond too. Mostly it's because all the best bearings are metric, and the locknuts are all metric diameters with 12 TPI threads. Are you doing this work professionally? It sure looks like work that should pay well.

[John S.]

Taper locks come off easy.
That's what the extra hole is for you take the two screws out and put one to one side. the other screw goes in the clearance hole and when tightened up it jacks the taperlock out of the hub.

I run a one man band job shop, technically retired in January but they won't let me.

[stevec]

I love taperlocks! true they can cure worn shafts but if used at the out set the shafts don't wear!
I can't believe how pretty the MIGed and turned motor shaft came out! And, it didn't warp?
You're an artist John.

[PixMan]

The taper locks should come out easy. When they've been on the hardworking end of an extruder (between the gear reducer and the hot extruder screw) for a great many years, completely neglected, you'd be shocked at just how bad they can be.

[stevec]

Curiosity made me check, 12 pitch in inch is really close to 2.0 metric.
BTW, I have a ½-12 tap that I keep hidden, just so I don't grab it and use it where I need a ½-13.
Dunno it's origin or need but remember, I NEVER throw anything out.

[John S.]

Definitely 12 tpi because it was an imperial shaft to start with.
I did check 2mm pitch but even on the short arm of the thread gauge you could see the run out error.

1/2 x 12 is very common here, it's 1/2" Whitworth but 1/2" x 13 UNC isn't as common here now all the car firms that were associated with American parent companies have long gone.

There used to be a lot of threads of UNF / UNC form but now most of our car firms have ties into Europe and the far east it's all metric.

[DaveH]

Nicely done John.

DaveH

[stevec]

(04-08-2013, 06:47 PM)John S. Wrote: I did check 2mm pitch but even on the short arm of the thread gauge you could see the run out error.

As did I, that's why I said "close"

[sasquatch]

Thanks for the interesting shop pics.