Member postings for Andrew Skinner

That looks like a resistance split phase motor. Instead of the capacitor providing starting torque, the start winding is wound of much thinner wire. The altered reactance/resistance ratio (called ‘Q” factor) causes the phase shift for starting.

Isolate the motor wire pairs and measure resistance and check operation of the centrifugal switch.

These two are ok, I think.

”Milling” here is a gerund, a verbal noun.

”Measuring” is a gerundive, adjectival to “instrument”.

Thanks, I’ll try that. I inherited lots of Clarkson cutters with my TS mill, many with chipped edges so might as well grind them off and use for facing.

This is more question than answer, but I read somewhere that you can stone the sharp corners of the endmill to improve the finish, obviously keeping that one just for facing cuts. Is this advisable? I haven’t tried it.

For similar reasons, the university newspaper was never allowed to abbreviate ‘Cambridge University netball team’.

I did chip in to the original thread, but realised I was starting to bang on a bit about power factor, and such.

In the interests of getting to the bottom of the issue, I’d still like to know if Andy Mawson’s leccy meter measures in kVArH or kWH. That’s absolutely key.

All the reps/technicians sent there to investigate did no more than clamp the supply cable, using P=IV (the ‘DC formula’ ), rather than addressing phase, ie P=IVcos[phi].

For example, if I powered up a fluo light fitting with no tube in it, I would see the full leading VARs supplied by the capacitor, shown as a significant current on my clamp meter. There would be, however, pretty much no charge for this on a domestic kWH tariff.

He got a great result from the supplier, but it still gnaws at me now and again that we haven’t fully ‘bottomed out’ the technicalities of this.

Edited By Andrew Skinner on 02/06/2023 12:26:30

Well, I’ve done the flats, separated the castings, mostly formed the hinge, and turned the fingers.

The casting isn’t big enough to achieve the 1” diameter of the hinge bosses, but I don’t think it really matters. My first time radial milling seemed to go okay (I’ve only owned the mill for a few months).

Not especially happy with the female hinge boss. I was aiming for a 6mm slot, but accepting it might cut oversize (I just machined the male part to fit). The inner sides aren’t very parallel, nor flat-bottomed. After some work with a file, the hinge fits but there is a small amount of play axial to the pin.

Cutter was a longish 6mm Clarkson which came with the machine. I guess the non-flat bottom is down to chipped teeth on the cutter. The non-parallelism is a bit more annoying - I assume the piece was flexing/vibrating.

Should I have gone for an even smaller cutter (5mm?), then stepped over to each side? No DRO, so I was at the mercy of backlash.

Ok, thanks. I’ve gone ahead and put flats all over it, so time will tell if it was worth bothering. Since I’m a bit lacking in experience I thought it might help.

Just arrived.

The instructions are lathe-based, but I’d like to use the TS mill. As it happens, Steveigtr has put out a set of videos of his build, which I’m working through. I’d be interested in his comments particularly.

Before separating the two halves of the casting, Stevie milled both sides with flat references, but not anywhere else.

Would it be wise to mill reference surfaces, horizontal and vertical, pretty much all over the piece before cutting in half?

^ thanks, the digital RPM meter and sender came with my Boxford VSL, but I managed to get its original Smiths meter going again, so it’s a free upgrade for the mill…

Edited By Andrew Skinner on 13/01/2023 18:21:23

Currently building up a mill control box (rev-off-fwd, e-stop, power and fault lights, rpm meter, speed pot) from an adaptable box and bits.

Another question, possibly for Steviegtr - since the new motor shaft is only 40mm, and the mount adapter is 10mm thick, I’ve only got a small amount of shaft inside the pulley, which is leading to vibrations if the belt is set to normal tightness. I’ve left it loose for now.

The motor shaft has a 6mm thread in the end. Would it be feasible to turn a shaft extension of 19mm diameter, with a similar thread inside, and lock the two together with a length of 6mm studding?

Also, I need to mount the RPM sender somehow. How did you mount yours?

That would be a good idea, that I might save till the bearings need changing.

I had some thoughts about the backlash in the X and Y directions. The screws are more worn in the middle, and I guess there’s some wear in the feed nuts as well. There’s a company in the US (Roton) that supplies Acme LH 5 tpi threaded rod for only about £12 per foot. With this, and a suitable LH thread tap, could I not make up some new feed screws/nuts?

Did that as well. It did work, and was how I diagnosed the source of the knocking.

Yes, I did that. Seems to have helped a bit.

Only when I’m using the fly cutter. I haven’t tried it with the new 3ph motor, which should be smoother, and the VFD hasn’t arrived yet.

I’ve temporarily rigged up the VFD from my morticer just for a test run, but I don’t want to change settings on that as it’s not an easy interface.

I’ve done an album:

Edited By Andrew Skinner on 01/01/2023 14:47:21

Right, I’ve finally fitted a 1 hp TEC motor with B14 mount on ally adapter flange as per the advice above. Cheers for that.

With the head stripped down, it appears that the play is indeed between the splined parts. The only slight ray of hope is that it’s similar all the way along the length, even the bit right at the top, suggesting that if I replaced the female part, that would make a big difference. I think the mill’s been used primarily as a drilling machine, given the awful state of the vice, which would have evened out the wear in the male splines,

Is there someone out there who could make a new female drive part? I could probably turn the round aspects, leaving just the splines to cut, or even fit a splined repair insert.

Since there’s no play anywhere else, I’m inclined to stop the stripdown there and reassemble with some new grease.

Edited By Andrew Skinner on 01/01/2023 14:51:56

Thanks for the pics. I think you might be referring to radial play in the spindle?

What I have is backlash between drive pulley and spindle. For example, as the fly cutter takes a cut, the backlash is taken up, and at the end of the sweep, the cutter overruns until the next cut, where the lash is taken up again with a knock.

I plan to strip down anyway, so will keep you posted.

Ah, mine’s different then.

While we’re on it, the spindle on mine knocks annoyingly when on the cut. I’ve traced the noise to rotary play between the spindle and its drive pulley. If I ‘brake’ the part of the spindle that protrudes next to the motor at the top, the noise goes away. On my machine, this part is a splined shaft.

Bearing in mind I’m fairly new to mills, would it be worth stripping the head down, and how would I take the play out?

Thanks for the tips, especially the video.

Frank/Andrew, have your motor mounts already been modified? I can’t find a modern motor with 5.5” PCD flange.

Steve, I couldn’t see it from the motor plate, but I take it yours is an 80 frame with B14’A’ type flange?