Phase Shift

I figure it’s time to talk about something else here besides health stuff.

I’ve wired in a few devices of late, and there are varied wiring situations I have to deal with in this case.

Now, as everyone knows, the supply side electrical line frequency, measured in Hertz, associates directly to the speed of the motor in revolutions per minute. A motor that works at one speed at 50 hz. will run faster at 60 hz., at the rate of 60/50, or 1.2 times faster.

Some motors these days are made for situations in which the speed at which they need to operate varies, and thus variable speed motors have been developed. These motors are controlled in their speed by adjusting the electrical frequency with which they are fed. This may be done manually or automatically, depending upon the application.

My new dust collector, for instance, accepts 240 volt (opposed phase) leads from a breaker in my house’s electrical load center, and uses a built-in inverter to convert that into 240v. 3-phase feed for the collector’s motor. The speed of the motor is controlled within a range of 40.0 hz.to 75 hz., and on front of the machine there is a knob with which one can adjust the frequency:

When you turn it on, it retains the last setting, in this case 45 hz.

As you go up in hertz, the speed of the vacuum goes up. Running at 40~50 hertz, the machine is really quiet. And I’ve found that despite the machine’s 450 lb ( 205kg) weight, it is quite easy to roll round and I’m now starting to see it as equivalent to a giant Festool shop vacuum.

A Variable Frequency Drive, or VFD turns out to be a useful little device. I’ve been learning more about them of late as I anticipate having a need for one if I get a machine from Japan.

With some kinds of machines, the rpm of a motor, converted into a given machine function like spinning a cutter head, it does not matter much if the difference in the frequency supplied is relatively minor, from 50 to 60 hz. say. A 1.2 x increase in the spin rate of the motor does not likely threaten the spindle bearings or cause an issue in the cutting of the material.

While cutter head speeds can be varied within a range, motors are used on some machines for other purposes, like feeding a quill downward, or moving a work table in any of the axes. With certain situations, for optimal finish on the part being worked, a 1.2 x change in feed speed may – or may not – matter. However at the very least the machine operator would need to be aware that the posted speed control settings on the machine are not going to be accurate if the machine is receiving a different electrical supply frequency.

If a workshop has 208v 3-phase service, as my old one did, they could plug a Japanese machine in without issue, as 208v. is only about 4% off the rating for the motor, and it will shrug that discrepancy off no problem. I believe the accepted input variance is +/-10% the motor’s voltage rating.

I had the convenience of 208v., 3-phase service in my old shop and I now have a situation where my source of power is going to be my house’s 100 amp single phase panel. That panel can have breakers fitted for 120v. service, or double pole breakers can be fitted, for 240v. ‘opposed phase’ power, which typically is used for an electric oven or clothes dryer. In our case, we have a gas dryer and oven, so there is a bit of space in the panel.

For my basement shop I have acquired a 10 horsepower Phase Perfect converter. It takes a feed from the household 240v. service and outputs 240v., 3 phase:

House’s load center is on the right, Phase Perfect in the middle, and the sub-panel to the left.

I’ve been looking in recent months at some different Japanese machines, currently located in Japan, mostly hollow chisel mortisers and milling machines. Domestic Japanese machines are configured for 200v. 3-phase service, which doesn’t match what I have: 240 volts is a bit too high a voltage for a 200v. motor I think. Happily there’s a convenient solution in this case: a VFD, or Variable Frequency Drive.

I can feed the household 240v output to a VFD instead of the Phase Perfect. The VFD device provides a variable hz. 3-phase output. If I set it for 60 hz. output, say, then the associated output voltage would be 240v.. This is the maximum for voltage given the matching 240v. single phase input. But if I set the VFD at 50hz. instead, the resulting proportional change for the voltage should set it down to 200v.

How convenient. I could provide a Japanese industrial machine with the frequency which will mean the spindle/drive speeds marked on the machine will be accurate, and at a voltage which is not only within acceptable parameters but spot on. A 5 hp. vfd costs under $300.00 which I think is pretty reasonable. It really means that importing a Japanese machine with a motor, or motors, designed for 200v. at 50 hz. is a non-issue, a problem solved perfectly and relatively inexpensively. At least compared to the kind of money you have to shell out for 3-phase transformers.

So, some more about the basement. I started from a good base, as the house is only about 10 years old and we have a full concrete-enclosed basement. To make it a warmer space I placed 2″ polyiso board on the walls, giving R-13, and then a grid work of 1x4s. This is what that looks like before the covering gets applied:

The grid allows me to easily chase wires, and the vertical sticks can be shimmed to correct for wows in the concrete, which are numerous I have discovered.

Building codes require that polyiso and other foam insulation boards be covered with a 15 min. fire barrier. The conventional material that is used is 1/2″ gypsum board. I didn’t want to use sheetrock however, but rather preferred plywood. I don’t much enjoy working with drywall, and a plywood wall seems more versatile, easy to attach stuff to, easy to remove to get in behind, etc.. And it certainly is more expensive than sheetrock, that should be noted. Plywood meeting the 15-minute fire barrier rating had to be 5/8″ thick, which is actually specified as 19/32″ (0.59375″), which is, after all, only an approximation as the actual thickness of the board is 0.5905″ or 15.0mm if you prefer to look at it that way. Anyway, all that aside, the other important specification was the use of exterior glue to hold ply laminae together.

In most building supply places and box store, a 5/8″ exterior rated ply sheet is a standard choice for residential construction, and can be obtained for around $22/sheet. It’s cheap and it is also crappy. Looking at this material at three different building supply places, all I found was warped garbage with rough face sheet quality.

In the end I found a material specified for underlayment, which met the other required criteria but at $43/sheet. So, after much consideration, that’s what I went with:

I’m running the single phase 120v and the opposed phase 240v. stuff in the wall, and on the face of the wall mounting EMT and junction boxes to run the 3-phase circuits. That way, if usage of the space changes down the road and the shop equipment removed, the 3-phase stuff is more or less an overlay and readily removed.

Let’s pan back a little further to see the chaos:

I’ve got the 240v. opposed phase circuit wired in so I have been able to power up the Harvey Industries 700 series dust collector. I’ll talk more about that in a later post. I’m liking it so far.

Here’s a view looking the opposite way:

The above is but a transitional stage in terms of where stuff is eventually going to be located. And you can see the pile of Cuban Mahogany there that is also in the way. Little by little we get it done, sometimes with a little outside help if need be.

Since we are looking in that direction, I might mention that I spent some money on a couple of router table upgrades, in the way of the Mast-R Fence II:

The old fence was a stout affair and had some decent functionality, and the new fence is also very robust and has numerous improvements, like the knobs for loosening the fence plates, whereas before you needed a tool:

The fence extrusion is actually a 5-piece affair, and the outfeed side is now micro-adjustable for jointing, instead of the plastic shims they used in the older models:

I usually opt to employ a back fence for runs of molding and the like, and don’t tend to change the out feed fence setting otherwise, but the new set up is certainly a lot more functional looking than the previous one with plastic sheet shims.

The old fence had phenolic fence plates secured with Allen screws on the front. The new fence uses integral sliding aluminum extrusions with clean faces:

Not pictured is the new cutter guard. I also obtained the Mite-R Slide II and its swinging blade guard along with the fence, so where does that leave me? Uh, needing to construct or obtain some sort of storage unit for all the router accessories.

Working on the new basement shop has been quite an undertaking. I’ve made solid progress in the past few months. It’s been interesting trying to figure out what machines can and will go down into the basement, and then arranging them in the space so that a workable situation is obtained. I have a long way to go yet.

I’m trying the router table out over in this corner, for instance:

Dust collection for the router needs to be worked out – it won’t be taken care of by the Festool mini vac you see next to the table in the picture, but rather by the big ‘shop vac’, the Harvey 700.

Here I have replaced a pair of existing plywood cabinets with plastic bins inside and an oak top above with a pair of roller cabinets utilizing the same oak top:

I am toying with the idea of putting my Kapex chop saw on the work surface, and the vacuum below. I sold my CT33 Festool vac to a neighbor and used the proceeds to help buy a newer Festool shop vac, the Cleantec 48 I think they call it. It gives me a fair bit more capacity in dust collection. The old one had fallen off a trailer at some point and had some broken off plastic bits, but still worked fine. I decided that it didn’t owe me anything after 10 years.

The new Festool shop vac seems a little more cheaply made than the old CT33, though it sports some improvements I guess.

When space is at a premium, and you have a bunch of stuff that needs to be shoe-horned in, then figuring out how to use the space as efficiently as I can becomes ever more important. I’ve made plans, and then as stuff comes into the space and I get a better sense of it, I revise accordingly. So, the shop space is currently in what we can call flux.

After the last shop I realized that I no longer wanted open shelves in a shop if I could help it, preferring the dust-excluding potential of wall cabinets with doors. I have several roller cabinets already, and they are a great way to store tools, etc., so I’m keeping them. In general though, I will try to arrange it so that heavier things are lower down, in those roller cabs, and lighter things are placed up high, in wall-mounted cabinets.

One exception to my overall aims of using cabinets, I do have one open shelf unit that I dragged home from the old shop. It was my shop neighbors, the price was free, and it is older and heavy built:

Getting certain machines on wheels allows for greater flexibility in using the space, and here I am starting the work to put wheels on the CB75F bandsaw:

I think the same treatment awaits the little Makita planer.

I’m not intending to do the same thing with any heavier machines I bring, save perhaps for the Hofmann slot mortising machine. I think it would be a good candidate for being placed on wheels — and then I remember that it already has concealed built-in wheels on one end. I just need to get a tow bar on wheels for the front of the machine.

The other stationary machines yet to make the journey from the old shop include the Hofmann mortiser, the Wadkin saw, and the Shinx surfacer. They will all go down there if I want. I’m also considering getting a new milling machine, and of course there is the thorny problem of jointing and planing….

All for now – thanks for your visit.