Brown & Sharp Surface Grinder

[Robo_Pi]

This is a great place to do your "plan". Sometimes you can follow a thread here and get what you need. Sometimes you just have to jump in like you did. SG's are a very deep subject and my foray into the abyss of gathering intell on them here was very satisfying. But it also made me very cautious as there are very few SG's around here and I've only seen basket cases for $4-500 and never $2-300 like you seem to have endlessly. Sketchy ones start at $1k+ and I'm not sure the more expensive ones don't have problems. Best of luck and good hunting.

Well, I don't know if this is a fluke or what. But this company currently has 4 surface grinders for under $300 if you want to count the rust bucket posted in the OP on that list. And they had a couple more that have already been sold. I don't know if this is a regular thing for them, or if they just happen to have a bunch of junk surface grinders right now. I'm hoping this is a normal situation. But it could be that come summertime they won't have any cheap surface grinders to play with. I just don't know.

Same things goes for the lathes and vertical mills. I've been watching and they just got in, and sold a couple pretty nice lathes and milling machines for under a grand. Again, I don't know if this is business as usual, or if this is just a fluke?

I'm hoping it's business as usual.

They have a really nice Sebastian lathe for $999 right now. I'd buy that baby if I could. But my truck needs a new clutch. So some other lucky hobbyist is going to end up owning that Sebastian lathe. In fact, I'm willing to bet that it's gone before the end of this week.

 

[Janderso]

When I bought my B&S 618 Micromaster, I took an expert with me.
I wanted a surface grinder but was not familiar with the machines.
Take your time and get some help. You will not be sorry.

 

[Boswell]

I didn't know that 3 phase motors would be compatible with standard residential electric service.

just so there is no mis-understanding. a 3 phase motor can run on standard residential single phase power WITH the addition of a phase converter. Apparently they are not too expensive or hard to install as I see them mentioned in many threads.

 

[Janderso]

I am moving my equipment to a home shop next month.
I chose to go with a Rotary Phase Converter which will give me all the options I need.
I did have a VFD for my Bridgeport at the old house, worked great.
We home shop guys have options and plenty of them.
You do need to open your wallet though

 

[Bob Korves]

If I can use the motors that come on these machines with my current 220v residential service, I'll definitely go with that. I didn't know that 3 phase motors would be compatible with standard residential electric service. So apparently I have a lot to learn about these motors. It appears I'll be dealing with the same motor issues with the lathe and milling machine too. I was thinking that I would need to replace the motors on all of these. I used to have a Bridgeport Mill, and a large South Bend lathe. Both of those ran on regular 110 AC. As far as I can remember that's the way those machines where when I bought them. I don't recall having motor issues with those. But that was quite some time ago.

It is quite easy to run 3 phase motors off of single phase power. It takes a VFD, variable frequency drive. Units are available to run 220 3hp for under $100. They are not difficult to hook up. The up side is that you also get a "turn the knob" speed (actually output frequency) control and a reversing control as part of the deal, and many more adjustment possibilities. Running a motor with them is simple. The issues come when the machine has more involved wiring, like contactors, multiple motors, magnetic motor starters, etc. A VFD needs to connect directly to the motor, with nothing in between or in parallel. This is not usually a problem for an older surface grinder, but many lathes and quite a few milling machines have far more involved electrics than just an on/off switch. The other issue is that the VFD does not change the voltage, only the a/c frequency. Changing voltage will require a transformer, and they are relatively expensive, bulky, and noisy. They also lose some efficiency. So, find simple machines with a motor that will run on three phase 220 and they will be easy to hook up to a single phase supply using a VFD. They are also often cheaper as well as better, many hobbyists do not want to or think they can mess with 3 phase due to lack of understanding, and the machines are obsolete for commercial work, so they are orphans, unwanted, and therefore sold cheap or scrapped. Which can be good for us, if we get to them before they go to the scrapper.

 

[Robo_Pi]

I'll have to look into the VFD. I work with electronics all the time, and I do all my own house wiring, etc. So I have no problem working with electrical components. Since I'm getting at least 3 machines what will most likely have 3 phase motors on them it might do well to go that route. I wonder if I could make the VFD portable and just wheel it around to the machine I want to use at the moment, instead of wiring it into a single machine permanently. I can't imagine why I couldn't do that. One VFD to rule them all.

I mean it will just be a hobbyist shop, so it's not like I'll need to have all three machines running at the same time. Sorry for being so frugal, but if I can cut the cost by 2/3 why not?

 

[Robo_Pi]

When I bought my B&S 618 Micromaster, I took an expert with me.
I wanted a surface grinder but was not familiar with the machines.
Take your time and get some help. You will not be sorry.

If I took an expert with me to look at these $300 surface grinders she would just look at me and say, "You can't be serious".

When your a "bottom feeder" you kind of just need to grab whatever looks like it might work and hope for the best.

I mean when you stop and think about it all I'm really doing is saving an old junk surface grinder from the scrap yard. If I took an expert with me she would just say, "Let the poor thing rest in peace".

 

[Bob Korves]

Moving a VFD often from machine to machine is rarely done. First, you get it all adjusted so they work well together, and when you move it, you will want to do it again for the next machine. If you used good connection hardware to make all the various wires hook up automatically by plugging them in at the next machine, and made them foolproof, it could work, but you would likely not want to change the settings all the time from machine to machine. Accidentally starting the VFD without it properly hooked up to a motor can maybe damage or kill the VFD. They really want to be hard wired from VFD to motor, with no other hardware in between -- "Idiot proof." It is possible to do otherwise, but I do not recommend it...

 

[Robo_Pi]

It is possible to do otherwise, but I do not recommend it...

Doing things that aren't recommended is my life story.

The bulk of my career was in R&D. In the 1970's I worked for a company that designed inertial guidance systems for ballistic missiles. At one point I was working on the motor controllers that go inside military tanks and keep the canon locked onto the target while the tank vehicle itself is bouncing all over the place climbing over ruts or sand dunes. So I have some experience with extreme motor control. Of course those were DC servo motors. I never worked with 3 phase AC motors before. But it can't be that bad.

I look into it. If it's doable I'll do it. If not, I'll just convert the machines over to standard 110/220v motors. I'll do whichever is easiest or the most cost effective for me. Obviously I'll need to do something as it appears that most of these machines are going to have 3 phase motors on them. But that issue will apparently exist for pretty much any machine I get. Unless I get one from Craigslist which will most likely already have a VFD or standard 110/220v motor on it already.

Worse case scenario I can always mount lawnmower engines on them and run them on gasoline.

 

[Dabbler]

Robo_Pi I do move my VFD around from machine to machine, so it can be done - within strict limits... All 3 of my 3 PH motors are 2HP, and all are within 15% of the same rated current - yes, not all 2 HP motors are alike. If your rated current is out by more than that, expect serious problems, like losing your VFD... (In my case 2 of the motors are rated at the SAME current and one is off by 6%)

- you can reprogram the VFD for any running current, but it is a pain, and you'll forget, and then the trouble starts....

My VFD plugs into the wall using a 4 pole 30A twistloc (or Hubbel, if you like), and the motor plugs into the VFD using a 20 Amp 4 pole twistloc.

I hope this helps. [Yes, I am too cheap to buy another VFD!]