Used Jointers

[Doug Donnell]

Ok, I am about to leave the house to look at a couple of jointers.

[minor rant - why do people put ads on CL and then not put phone numbers to respond to... then when they respond to an email they limit their response to "yes, its still available!" Ahh... ok, how do I contact you???? Oh well, no big deal... rant off]

Couple of questions from the learned audience...

I have a 36 inch Veritas precision straight edge and automotive feeler gauges to check for flatness in the tables and fence. How much is too much space? Being able to check is meaningless unless I know how much to tolerate.

Other question regards 3 phase power. Considering one that is 3ph and comes with a converter. What should I look for or be concerned about? How much value should I put on the converter, and are some better than others? In short, any pitfalls I need to be aware of?

Of course, I am about to leave in a few minutes so I need some advice pretty quick. Thanks for any input.

Doug

[Doug Donnell]

Looked at a 6 inch today and posted some questions in a different thread.

Still seeking some advice re: 3 phase motors and phase converters. I know nothing of them and need to know if I should avoid that set up or consider inspecting the machine. It is an 8 inch and assuming it is in good shape with flat tables, I would consider it. The phase converter just makes me a tad nervous....

Doug

[Dave Lehnert]

Originally Posted by Doug Donnell

Looked at a 6 inch today and posted some questions in a different thread.

Still seeking some advice re: 3 phase motors and phase converters. I know nothing of them and need to know if I should avoid that set up or consider inspecting the machine. It is an 8 inch and assuming it is in good shape with flat tables, I would consider it. The phase converter just makes me a tad nervous....

Doug

From what I understand using a phase converter is no big deal. I have no idea what one cost but for what Grizzly is selling 8" Jointers for now days I would have to get a used 3 phase unit for nothing to consider it.

[keith ouellette]

I don't know what size jointer your looking at but You will need to use mor than a 36" straight edge (in my opinion) to see if the tables are in the same plane.

If the jointer is at a power source I would face joint a 36" long board and check that with the straight edge. Across the length at each edge and on each diagonal.

Also:

you can check if a 36" section of the table is flat with the straight edge, face joint a board, then place the face of the board on the part of the table you checked. If it doesn't rock then I think its set up fine.

I'm not 100% on that advice because I haven't checked a jointer that way. Hopefully someone else will chime in soon.

[Bob Aquino]

Originally Posted by Doug Donnell

Looked at a 6 inch today and posted some questions in a different thread.

Still seeking some advice re: 3 phase motors and phase converters. I know nothing of them and need to know if I should avoid that set up or consider inspecting the machine. It is an 8 inch and assuming it is in good shape with flat tables, I would consider it. The phase converter just makes me a tad nervous....

Doug

Doug
There are three ways to convert normal house current to three phase. A static converter uses capacitors to create a third leg long enough to kick the motor off then it runs on two phases. Thats why you only get 2/3 of the motors capacity on these devices.

A rotary converter is similar to a static, but it uses an idler 3 phase motor to regenerate the third phase. So what you get is true 3 phase power. You need to have the converter running before you start any other machines off of it. The idler motor is usually larger than the largest load. If you buy one off the shelf, they are not cheap, but they let you run multiple machines simultaneously. Normal size seems to be 5 hp minimum going up to 10. More than that and I think you will watch the neighborhood lights dim.

Last option is a VFD or variable frequency drive. These are electronic devices that take 220 normally and create a clean 3 phase output via solid state components. As an added bonus, they can vary the output frequency which will also vary the speed of the motor. They can also help to brake the motor by injecting dc at shutdown. Some of the higher end units can compensate for load on the motor. You can be into a vfd for a 1 hp or less motor for less than 150. 3 hp is about the max you will find a vfd for that will run on 220. You cant swap outputs on a VFD when its running, they don't like that much. So its pretty much a one vfd per machine deal.

So should you avoid them, I dont think so. I would calculate in the cost of a converter with the overall cost of the machine. Some machines actually run better on 3 phase, especially if you want variable speed (think Lathe, Drill Press, Bandsaw). The new lathes that have digital readouts and electronic speed controls are actually 3 phase motors with a VFD controlling them.

I have a big bandsaw running on a vfd right now and will be restoring a Delta RAS that is a 3 phase motor this winter. 3 phase motors are much more bulletproof than their single phase cousins and generally tend to run smoother and quieter. Here are three examples, the bandsaw is mine, the lathe and press are my brothers.

Bandsaw:


Drill Press:


Lathe:

[Dennis Ford]

If a table (either infeed or outfeed) is crooked enough that you can measure it with a straight edge, that may be a problem. It is more likely that they each will be straight but not parallel to each other. The hard part is to determine if this is something you can fix (adjusting jibs etc) or if it will require some very expensive machine shop repair.