Someone School me on Surface Grinders please.

[Hephaestus29]

So I’m doing my stint in the Tool Room in my
Apprenticeship for Machine Repair. I’m
currently running surface Grinders, manual
mostly but I did run the Automatic once to
grind big 12” parallels.

I’ve been on the grinders now for about a
month and I can see what an asset they
could be in a home shop.

The only ones I have ran so far are foreign jobs
made in Singapore called Okamoto.

An automatic would be really nice to set up
and let run while you do something else but
if I have a small job, I can knock it out pretty
quick on a manual.

So I guess my Question is:

WHAT TYPE OF SURFACE GRINDER WOULD
YOU LOOK FOR ?


I’ve only ran the Okamoto and they seem to be
fairly smooth.

What if I get one that needs work, are parts
cheaper on the foreign jobs v/s Old USA Iron?

Where is the quality at? Old USA Iron or newer
machines?

On the 12” parallels I ran, in the vertical
position, I was able to hold
.0001 over the entire length of 12” when it
required .0002 and I did that on the manual
machine. In the Horizontal position, .0002 was
the best I could do due to a bow in one, and
that was good enough so I called it done.
The parallels were 1x2x12

Thanks for any input.

 

[davethorik]

Okamoto grinders were made in Japan last I checked, and they are good heavy duty machines that hold up to daily production well. Way too expensive for a home shop unless you found used.

Most home shops I've seen, if they have a grinder it's usually some old American iron. And usually on the small side, even the small machines have a pretty large footprint.

 

[matt_i]

Harig 6x12 would be my choice.

-They can be worn. You'd probably have to print the part on a surface plate (like you were going to scrape it) to assess dimensional issues with parallelism.

-They can have spindle bearing issues.

Usually you'll see chatter in the surface caused by bad bearings.

Careful of the wheels, you don't want to blow one up.

Be really careful of the grinding swarf. Its superfine and is attracted to other oiled-way machinery and will trash other machines quite quickly. So keep it separated with other "dirty" fab machinery just like you wouldn't shower your Bridgeport mill with the spark-stream from a 4-1/2" angle grinder...

The guys I worked with swore to buy the Harig way oil even though its like a $50 investment but they claimed using typical Shell Tellus or Mobil Vactra way oil messed things up in a bad way. I never chose to find out what could go wrong.

Edit: be really careful when moving one due to this issue: On a classic 6x12 of several different manufacturers, the grinder just sits in a stamped pocket in the sheetmetal stand, on a rubber mat, there is no physical connection other than gravity. So when you tie it down for transport be mindful of this....

Edit #2, its better to buy with a magnetic chuck if possible, but you can easily get mag chucks "included" in a package but they have lost grip...the good news is you can test them out easily. New mag chucks are expensive!

 

[metlmunchr]

Okamoto is generally considered to manufacture the world's best reciprocating surface grinders.

A lot of decent grinders have been manufactured in the US in the past, but in looking for an affordable used grinder, condition is far more important than brand. To put it bluntly, a large percentage of toolroom size grinders are for sale because they're worn out.

That said, how much wear is acceptable is dependent on the intended use. For example, I've got one grinder with way too much wear to be useful for flat grinding like on die sections and similar stuff, but I use it with various fixtures for tool sharpening and similar work, and its fine for that.

The only thing I can tell you about parts is to never buy one that has any missing parts. Many brands are no longer manufactured so there's no parts available other than in the used market. And among those with parts still available from the manufacturer, the cost of most any seemingly simple part will often be more than you paid for the grinder. There's no such thing as a reasonably priced machine tool part.

Practical Machinist has a forum section on grinders and grinding operations and several knowledgable participants who can give you details about how to check a used grinder for wear.

 

[Hephaestus29]

Thanks for the replies, good info.

 

[banging away]

Be aware when moving a surface grinder that the table is often
not held in place. It simply rests in the ways. You can pick the
table up and walk away (on the smaller machines at least). Be
sure to tie the table down to prevent it from sliding off onto the road
as you drive along. On mills and lathes the movable parts are
held captive, on a surface grinder they may not be.

 

[metlmunchr]

Be aware when moving a surface grinder that the table is often not held in place. It simply rests in the ways. You can pick the table up and walk away (on the smaller machines at least). Be
sure to tie the table down to prevent it from sliding off onto the road as you drive along. On mills and lathes the movable parts are held captive, on a surface grinder they may not be.

Good point. And a surface grinder shouldn't be tied down by placing straps across the table. You tie it down to the truck or trailer by securing the base and then tie the table off to the base such that it can neither bounce around or slide along the ways.

 

[VocaTexas]

On small K.O. Lee grinders you are advised to remove the table before transport. The table rides on small rollers and the rollers can be damaged by shock during transport.

Steve Summers on You Tube purchased a small K.O. Lee grinder fairly recently. Give his channel a look if you want to learn about surface grinding in a hobby type environment.

 

[MushCreek]

I have a Harig 612 I got at auction for $350. at that price, I couldn't pass it up. They are small and light, so easy to move. I've done lots of very close work on the little Harigs. If I'm running a machine all day, though, roller ways are a lot easier to crank. I use a Kent at work that's deadly accurate.

As said, the spindle bearings can go bad. Last time I priced a set, they were around $400, and have to be installed in a very specific way. Harig way oil pumps go bad, too, and they aren't cheap. Some grinders couple the motor with the spindle with a lovejoy coupling, and when the rubber spider goes bad, the finish will really suffer. Grab the spindle and twist it back and forth. If there's any slop, it's probably the coupling.

DRO's for grinders are somewhat expensive, but very handy for some types of work. Probably not needed for hobby work.

 

[Hephaestus29]

On small K.O. Lee grinders you are advised to remove the table before transport. The table rides on small rollers and the rollers can be damaged by shock during transport.

Steve Summers on You Tube purchased a small K.O. Lee grinder fairly recently. Give his channel a look if you want to learn about surface grinding in a hobby type environment.

Yes I watch Steve Summers Channel and saw
that video, Keith Fenner just got one too.

 

[ericlar80]

You have to remove the table before moving; don’t even consider leaving it on. The bearings will dent the ways and cause the table to not move smoothly or grind to its full accuracy. We have an okamato and a Kent at work.