Brown&Sharp No2 surface grinder any good?

[Eyecon]

Multitap transformers are available to boost the 3 phase voltage. Most of the smaller SGs used 1HP motors so the required transformer would be very small. On that small a set up, it would be practical to put the transformer on the output side of the VFD, a practice not recommended in larger motors.

Belt drive SGs by B&S used specially balanced motors to minimize vibration.

appreciate the info on the belt drive motors. I know it's probably ok to use a step up transformer with smaller motors and VFDs but I haven't seen any small 3 phase multi-tap transformers before. The ones I could find were in the 1K price range which is too expensive for a 1.5K piece of equipment.

 

[Dabbler]

John N has a couple, and I think that Tomm Kitta has one that has a 2:1 ratio.

I'm of two minds on this subject. When I was looking for a surface grinder, I turned down several in the under 1000$ range, purely because of the voltage. I ended up paying over 3500$ for a 240V 3PH Brown and Sharpe. I suppose that I could have just purchased an earlier one and fixed the voltage problem...

My point on the motor is that you certainly can replace the motor. A belt drive one is far easier than an inline one. You will see some surface degradation, but, heck, it is a hobby, right? For the nitpicky, there is always lapping post grinding....

 

[Susquatch]

So bring a small blank with me to grind? I’ll definitely check out those videos before going to see the machine. Thank you!

To be clear, I'm a brand new SG user. So take everything I'm about to say with a VERY big dose of salt.

I think it's ok to bring a piece of stock and a tenths micrometer, but I wouldn't let bad results turn me off too quickly. If the machine isn't setup correctly you won't get good results. Setting it up is no piece of cake and could make a huge difference.

I think it's more important to check the operation, bones, and potential of the machine. Do all the cranks move smoothly throughout their range? Is the spindle quiet and smooth? Are all the parts there? Does it look properly maintained? What condition are the ways in? Does it have a chuck and how much of it has been consumed? Is it well dressed? How many stones and stone arbours do you get with it? Does he have a balancer for it too? Does it have fences and if so, are they all there? Are the stone tools there? Diamond dresser, and spindle stone removal tool?

Of all of these, condition of the machine, the ways, the table controls, the motor, and the spindle are the most important.

 

[thestelster]

John N has a couple, and I think that Tomm Kitta has one that has a 2:1 ratio.

I'm of two minds on this subject. When I was looking for a surface grinder, I turned down several in the under 1000$ range, purely because of the voltage. I ended up paying over 3500$ for a 240V 3PH Brown and Sharpe. I suppose that I could have just purchased an earlier one and fixed the voltage problem...

My point on the motor is that you certainly can replace the motor. A belt drive one is far easier than an inline one. You will see some surface degradation, but, heck, it is a hobby, right? For the nitpicky, there is always lapping post grinding....

And if you're really concerned about surface finish due to motor imbalance, you can order any Baldor motor to be dynamically balanced. For a service charge of course, app. $500.00.

 

[Tom Kitta]

Just get a transformer on auction - or sometimes even kajiji - I got my 600v - 460v transformer for $60. My 240v - 600v for like 100++

They are not expensive and you can find them around once a year or so - in AB.

For say 240 --> 480v you can just get three 1ph cores and make yourself one for around 200 CAD, brand new.

 

[TorontoBuilder]

Thanks again for all the info…looks like there are several variations of this machine depending on the year. I’m also concerned about the motor which the seller says is a 600V 3 phase. None of my vfds can do more than 380v line voltage so I’m not sure if this unit will be usable in my shop unless I change the motor. Also to @Dabbler’s point about specialty motors for SG spindles , I guess that’s for direct drive and I’m not sure if this unit is the direct drive or the belt driven version. I’ll go and take a look anyway if for nothing else to learn…seller seemed friendly on text messages

We had to buy a rotary phase converter, and a transformer for our surface grinder. Add about $1500 to your costs... for used equipment.

Upside you can now buy other 600V machines that are usually well priced because who has 600v power

 

[Dabbler]

If I may add that my motor rewinder/industrial guy scared me off the 440V grinder (for 550$!!) from Ontario because he quoted 4000$ for the same kind of transformers that Tom finds.

The takeaway is that if you are looking for a used grinder, you might be open to a used transformer? There's lots of help here on the forum for just about anything machinery related.

 

[Dabbler]

[update] just a thought. He has to be making the right voltage to use it. He may have a transformer there that he would part with for a price. It doesn't hurt to know what that price is. It may save you a search if he could provide it also...

 

[Rauce]

Why not rewind to 240v?

I’ve had it done twice, both for milling machines with unusual motors. Cost me ~$400 each time.

 

[TorontoBuilder]

Why bother with a worn out grinder from the 1940s at 1500 bucks plus whatever costs when good grinders come up all the time for $1500 that are 240v and lightly used?

If you want a grinder I assume you want the precision that should go with such a machine. I can't see that particular B&S delivering the goods. The used equipment dealer even hints there may be issues. I can't recommend passing on this particular machine strongly enough.

 

[Mcgyver]

The motors that are included with a surface grinder are usually balanced, and not regular run-of-the-mill motors. That being said, you can still do good work if you put a 1Phase motor on it. You surface quality will suffer, but you can still hit your dimensions.

.
Perfectly stated.

None of my vfds can do more than 380v line voltage so I’m not sure if this unit will be usable in my shop unless I change the motor. Also to @Dabbler’s point about specialty motors for SG spindles , I guess that’s for direct drive and I’m not sure if this unit is the direct drive or the belt driven version.

No, its for a belt drive, although direct drive would obviously be crucial. vibrations carry through the machine. Don't change the motor, get a transform (autotransform 1P 240 - P 400V or so, come up for sale frequently on kijiji) then a 400 volt VFD. I would not change a SG motor, as Dabbler says. On quality grinders they are precision balanced and you will see the difference in surface finish. Plus, with 3P there is less torque cogging than with 1P - another thing important to finish. Also needs a high quality belt, any variance in belt width makes for nasty vibration. No Canadian tire belts! (I wouldn't put one of them on a power hacksaw lol)

I made the mistake of swapping motors 25 years ago when new to grinding but thank goodness didn't get rid of the motor. Made an RPC with a transformer, put the balanced motor on and got my finish back. Getting a really great finish on a small light grinder is doable, but you have to get everything working in your favour.

 

[Alawishes]

I have a B&S #2 that I got at an auction for $400. Once home I found it needed new spindle bearings, which are precision ball bearings — a friend of a friend managed a bearing shop in Calgary and I got them at his cost of $500. Ouch! Interesting, the bearings came with greasing instructions… no more grease than 15% of the available volume. I would have filled the bearings :-(. It has a 3ph motor so I found a VFD on eBay and that works well. No to finish grinding two new bushings I made and I can reassemble the table.

 

[Mcgyver]

Yeah, its never filled, they'll overheat, but I recall 30% as the usual recommendation ....of course do what the bearing maker says. I may be singing to choir, but exercise lots of care installing them! Never apply force through the rolling elements etc. Also pay attention to what grease. Some aficionados claim you must use the uber expensive Kluber spindle grease. I always followed SKF's recommendations and used their grease, which they recommend with super precision bearings and which is reasonably priced. As such, figuring they know a thing or two about bearings, kind of makes the uber expensive stuff seem like a bit of BS.

 

[Bandit]

Grease is very much like engine oil, every one knows what works or should be used.
In the centrifuge that I used to run before I retired the manufactor recommended Kluber grease and oils, that's what we ran. It was turning at 3000 rpm, the drum ran this speed, about 1500 lb., the main shaft was a 1000 or so lb. and ran a little slower,( this was smaller unit). The amount of grease and oil cost verses what the rebuilding cost made it easy to figure.
Some bearings after lubing/greasing, require a plug or the zerk to be removed and machine ran for a bit to allow extra grease/lube to be pushed out, this limits lube pushing past seals and or over heating.
A case of having a manual and reading it verses no manual, let's use what we got. Sometimes it is hard/impossible to get the needed lube, a cross reference between lube manufacturers can sometimes help. Looking for #2 hydraulic oil for the grinders in other posts, I had a look in cross references, not much, a few outfits never heard of too. Use what can be found, others are using, cross the fingers.

 

[Alawishes]

Hi Eyecon, I have a #2 B&S surface grinder, bought years ago at an auction for $450. That was the cheap part. Being a 3phase motor I latched onto a VFD, and that seems to work well. The precision spindle bearings ended up being toast, but lucky for me (with good connections) I managed to get new ones at a local bearing supply store at their cost of $500. I’d hate to think of normal retail cost on those. Interesting installation instructions with the bearings — the amount of grease is not to exceed 15% of the bearing volume, otherwise overheating can occur. I would have filled them up if not breaking down and reading the instructions :-(. It’s still not back together, as I’m making some new hardened bushings for the table moving mechanism but I’ll get there.