220 receptacle questions and "jointing" planer blades

[stevo wis]

Hi Folks,
I just picked up a 220 volt radial arm saw that draws 9 amps and has a 15 amp plug on it.
I also have an unused circuit that it could plug into that previously ran a planer. It is a 30amp circuit with a 30amp receptacle on it and has 10 gauge wire.

1. Should the breaker be replaced with a 20amp or 15amp so that it is closer to the draw from the saw? My understanding is that the breaker shouldn't be much higher than needed.
2. What is normal practice or code for matching the breaker, receptacle, an plug? It is difficult to find information for matching up the plug and receptacle for 220. If for example if I go to 20amps, would it be a problem to use the 15amp plug and outlet. Most of the information seems to dwell on 15 amp outlets on 20 amp circuits for 110v.

Any help would be appreciated so that I can get the right pieces and get it wired.

3. Unrelated, does anyone go through "Jointing" planer or jointer blades after sharpening and installation? From what I gather, after installing blades a stone is lowered to the blades on a running machine to grind a slight micro bevel and make sure that all blades extend the same amount. This seems like a very scary operation to be that close to a running cutterhead and I would guess that most people send out the blades for sharpening and nothing more. I have an old 18 inch yates armerican planer and the manual says to do the jointing.

thanks,

Stevo



thanks,

Stevo

[Kevin Jenness]

I have a Powermatic 160 planer with an onboard jointer and grinder. When dull, the knives are jointed and then ground until the land or flat is almost gone. I can't imagine jointing spinning knives without a solid and precisely controlled fixture.

[Jason Roehl]

The breaker protects the circuit wiring, not what’s plugged into the circuit. Think about how many times you’ve plugged in a 16-gauge lamp cord into a 15- or 20-amp receptacle.

Put a plug on your cord to match the receptacle and don’t give it another thought.

[Jim Becker]

No need to change the breaker or even the receptacle. You can change the plug on the tool or make up a short pigtail with a 15a 240v female on one end and a 30 amp male on the wall side. I just did exactly that for several tools in my temporary shop. The "machine shared circuit" is 30 amp; the tools vary from 15a for the Sawstop PCS to 20 amp for the MM16 and lathe to 30 amp for the J/P. The wall side is 30 amp twist locks. The machine side is whatever it needs to be.

[Andrew Hughes]

I’ve jointed my blades on my jointer while it’s running. It’s pretty uneventful and your correct it does put all the blades in a tighter cutting circle.
It also makes the machine loud or louder. Jointing adds a small heel on the knives the bigger the heel the louder the machine will get. A large heel also pounds the wood and leaves a undesirable surface esp on hardwoods. Remember I’m sharing my experience with a jointer.
With the current jointer injury sharing I don’t recommend it. Setting the knives with a quality dial indicator is a better way.
Good Luck

[Kevin Jenness]

I can't imagine jointing spinning knives without a solid and precisely controlled fixture.

Strike that- I can imagine it, but I wouldn't recommend it. It's the equivalent of cleaning a running belt in a wide belt sander with a hand-held rubber stick. What could go wrong?

[Tom M King]

I admit I sometimes slip, and call it 110, and 200, also. I lot of us grew up with Fathers, and Grandfathers who called it that, because Edison decided on 110 volts to run his light bulbs. We're approaching 100 years now, since American voltage was increased to 120 volts, and 240 volts, for various reasons.

Let's all try to help new people starting to understand electricity by calling it 120V, and 240V. It still confuses a Lot of people.

I never joint jointer knives. I do hone them by hand, on my waterstones, off the jointer, if they need to be sharpened a little, but don't have any knicks in them.

[Mike Cutler]

You're fine the way you are. The NEC stopped at the receptacle in your example.
If you want to install a lower rated breaker, you can do that also if you desire. Some folks feel safer doing this. As long as the breaker doesn't exceed the ampacity of the conductors, you're good.
You're tools may be rated for 9 amps, but it is doubtful you will ever pull that much during "normal" use.
Question #2 is one that will be debated until the cows come home. In the end, it is up to the local inspector to make the final call.
Change the plug on your machine, not the receptacle in the wall. The receptacle installation in the wall is absolutely covered by the NEC.
There are also many combinations of UL approved adapter cords available, if you're uncomfortable with installing your own plug on the cord.

[Charlie Velasquez]

As Mike said, the NEC stops at the receptacle. I would change neither the circuit breaker nor the outlet.

But if you do change the circuit breaker, then NEC says you must change the outlet to match.

With a few exceptions (I.e. multiple 15 amp outlets on a 20 amp CB, or dedicated circuits for motors or welders) the CB and outlet are supposed to match.

[Mel Fulks]

I’ve never jointed any knives or worked with anyone who thought it made any sense, especially if you use a good grade of steel like real
M2 or T1. One vendor told me the same thing.

[Mel Fulks]

Even though I have never seen any reason to joint knives, I do acknowledge it is a “real thing”. I was told it was most often used on
big commercial orders .
The way that gives sharper details is to tilt the grinder several degrees and go over the knives leaving a slight bevel. On a profile with
a lot of ups ,downs ,and crisp corners you might have to use several “wheels” carefully dressing each.

[Anuj Prateek]

No need to change the breaker or even the receptacle. You can change the plug on the tool or make up a short pigtail with a 15a 240v female on one end and a 30 amp male on the wall side. I just did exactly that for several tools in my temporary shop. The "machine shared circuit" is 30 amp; the tools vary from 15a for the Sawstop PCS to 20 amp for the MM16 and lathe to 30 amp for the J/P. The wall side is 30 amp twist locks. The machine side is whatever it needs to be.

Hi Jim,

As was suggested in another thread, all 220v sockets are 30A in shop. Shops is almost complete - some painting work remaining.

I got few machines assembled (bandsaw and tablesaw). I made a short adapter with 14-30 plug on one end and 6-20 receptacle on other using 10 gauge wire. Tested with both TS and BS, worked well. Now I have to duplicate it for individual machines.

Read your comment. What is pigtail in this context? Is there any advantage of using it instead of single wire?

[William Hodge]

I can't imagine jointing spinning knives without a solid and precisely controlled fixture.

Strike that- I can imagine it, but I wouldn't recommend it. It's the equivalent of cleaning a running belt in a wide belt sander with a hand-held rubber stick. What could go wrong?

I saw this go wrong.
Not a wide belt sander, but a 48" wide double drum entry door sander in a shop. It was a big old cast iron sander with12" diameter drums. The normal shop practice was to open the cover, start the machine, and clean the drums with a hand held rubber stick. One day I saw a worker sand his hand really badly.

[Jim Becker]

Read your comment. What is pigtail in this context? Is there any advantage of using it instead of single wire?

I've only done this with machines that come "un-corded". I do a short pigtail of about a foot or so on the machine and then create an appropriate length extension to the receptacle. I use twist locks. This gives me a 100% positive disconnect right at the machine. It's also handy for the rare time when something has to move as there's no dealing with a length of cord getting in the way, Yes, this method does cost more, too, but I'm fine with that. Others, maybe not so much.