What's new
What's new

Depth of Cut - Surface Grinding Dry

Cphockey16

Plastic
Joined
May 28, 2020
Hey guys. Hate to start a new thread but couldn't find anything that quite answers my question.

I'm an apprentice - just started surface grinding recently. I have to finish the length on some 1.25 in pins. I was wondering, do you guys have any strategies for hogging material without coolant? Everything I've ground up to this point I've been taking my time - .0001-.0008 on downfeed per pass. I've got about .040 to take off these pins - using a 46 H 0.5 in wheel. Can I get away with taking .002-.003 a pass while roughing, so long as I let them sit and cool? Or will they get too hot?

Thanks!
 
Hi,

If you are holding the part upright in v block or collet fixture then I would plunge grind most material off first. Dress your wheel very open.
Ex. position nearly full width of the wheel over the pin, downfeed 0.0005" at a tme and move table from left to right, another 0.0005" and go other way etc. stay about 0.0015" of your go to. Move wheel over another width and do the same until you see surface blending. Redress your wheel and finish to size using standard grinding traverse.

If you notice pins are getting too hot then simply dip the in water between roughing pass.

Kamil
 
I rough at 0.003" all the time on a J&S 540, with a 0.020" crossfeed, and until I fitted coolant about 3 yrs ago, did it all dry.
These were on larger flat parts though, and plenty of surface area for heat to be conducted away. Pins will definitely get a little warmer :)
An H is a fairly soft wheel - are these hardened pins you're grinding?
 
We keep a squeeze bottle of water soluble coolant handy and cool the parts every so often to minimize distortion. In a pinch we'll grab a water bottle and just poke a little hole in the top - works fine for the kind of stuff your describing.
 
I have a large grinder 14x48 10 hp, I only take .001 per pass, anymore the stone degrades...Phil

I'm with you. I have run Mattisons with 3" wheel width and can't manage much more than .001" downfeed with high (1/3 wheel width or so) crossfeed stepovers. I think these guys are doing little cross stepovers though so they can take a larger downfeed that way. I don't like grinding that way myself. Too much potential for wheel breakdown across the part and takes too darn long. You do generally need to use flood coolant to do the high cross feed though.
 
Last edited:
The biggest issue with grinding pins to length is that when they cool, they shrink.
 
Jesus, .040 on a surface grinder? if I had 2, id hit it on the bench grinder first, if 100, id make a block to dim. +.005 and whack that off on a disk sander, if 1000+ make a block with ten holes.
 
The holding ability and wheel RPM limit the infeed. One can down feed .005 - .025 grinding mild steel and pull/drag the wheel through coming across the part from the grind-side (if that would not harm, throw the part ort drag down spindle RPM). Coming across from the climb-side would/might break the wheel or throw the part. I have hogged parts until they turned red with heat when a machine part needed to be made as fast as possible to get something running. Parting wheel the same come hogging across only from the grind-side and pass free from the climb side.. Try to never blow a part off the chuck. Nobody expects grinding to be fast so you can take your time and not make scrap. Heat growth is the bugger that makes undersize parts...and burning makes parts out of flat/warrped.

Agree, this kind of grinding, hogging is not for the new guy, best to do everything with up most caution -> But learn the difference between the "Grind side" and "Climb side".

1.25 pins? Carbide or steel? how are you holding them, standing up in a v block? horizontal in a V block? Are you incrementing crossfeed across?

IF standing in a V block, likely I would down feed a good portion of the wheel width (perhaps full) across the part end down to +.005 of finish size with down feed .002 to .004 (slower across) on the grind-side and only .0001 to .0004 on the climb-side.

I would have my dresser set .0005 higher than the part and left on the chuck..at finish of rough-in, I would skim the diamond and go back to the part for the .005 plus whatever proves to make finist spec. After a couple of parts, I would make .0002 close to spec with not measuring.

Standing rounds in a v block it is good to have a tall bump stop high on the part to the Go Direction..and to have a shim under the foot of the part because V block rounds tend to harm the chuck surface.

The Go Direction is the way it would go flying if left lose. often if you can push a set-up over with 3 finger push it is not a good set-up / learn how to make solid setups.

Hard steel and carbide are not easily hogged so don't even try.
 
if you think grinding will be your frequent job you might pick up an aquarium pump with a 5 gallon and fudge up your own coolant system. Washing soda and water makes a simple coolant.
Some shop owners don't want coolant on surface grinders but it really helps in grinding.
 
As cyanidekid mentioned, quantity makes a big difference on the choice of method.

Another option for the roughing stage would be to mount a cutoff wheel on the grinder and mount them horizontally taking off most of the .040" in a single pass either by downfeeding at small increments (much better), or by creep-feeding at full depth (unless you have a very rigid setup and you are very careful, a lot cn go wrong this way).

Paolo
 
This type of thread is why I (and I'm sure many others) love this forum. So much knowledge gained over a lifetime of work being freely shared - available just for taking the time read and absorb. It's humbling to see how much I have to learn.
Thanks to all of the contributors here.
Martin
 
Size of the grinder matters. You'll see claims of 0.005" removal for Norton SG wheels. Maybe so, but not on a light 612 grinder. Those wheels need pressure to fracture properly and aren't really a good choice for a small grinder at all. Use a white wheel of an appropriate hardness for the pin hardness. Hard wheels for soft steel, soft wheels for hard steel. Note that soft steel doesn't usually grind well, though I do it all the time. Dress the wheel open; that means running the diamond across about as fast as you can turn the crank, with maybe 0.0005" downfeed. We usually make ring fixtures for grinding bunches of pins. Google "circle packing."

Whenever you grind anything, think of the worst possible thing that can happen. That might be a V-block lifting on the right hand side and levering itself into the wheel. Thus the recommendations of a good safety block to the left of the V-block. After you think of the worst thing, think of the second and third! Safety first.

Down feeding while going back and forth over one spot is fast as long as you keep the parts cool. Don't forget to raise the wheel for the next step over!

I love to grind. It's the easiest job in the shop if you know what you're doing, and seems to pay the best.
 
The problem with trying to provide efficient advice for requests like this is the complete lack of information from the OP.

Material?
Hardness?
Quantity?
Length?
Squareness tolerance?
Flatness tolerance?
Length tolerance?
Finish tolerance if any? I’d step up (down?) to 36 I or J wheel depending qty, finish,hardness.

Advice could be very different if pins were, say, 10” long vs say 1” long.
Ditto quantity 10 vs 1000; and does job repeat?

smt
 
The drive can be important for hog grinding. Often a 3/4 or better HP motor and a direct drive are needed.
A big B&S 1024 micromaster with 5 hp and belts drive is not a hogging machine because of belt slip, but a B&S 618 with a 3/4 hp and direct drive is.

like Conrad said a light-duty machine may not have enough weight in the wheel head to produce the pressure needed. Think about how much arm pressure you might push a part into a bench grinder wheel.

*Best to not consider Hog grinding until you have many years in the trade.
But every grinder hand should think about Grind side / Climb side for all grinding.

Climb-side is the part traveling a left direction into the wheel (on most common surface grinders.

The Climb side sucks the part into the wheel taking up any slack in the travel to make a heaver than intended/expected amount and can cause a fail set-up, throw a part, break a wheel, burn up a motor..

QT op[Can I get away with taking .002-.003 a pass while roughing, so long as I let them sit and cool? Or will they get too hot?}

To hold close sizes and avoid burns at least a hand spray bottle can be a huge help.
It takes a very long time to bring a part down to 70* gauge temperature.

You might travel a little slower and try .0002 on climb-side and .002 on the grind-side ..with a spray of coolant every once and a while.
 
oh my god, I guess grinder hands have a different take on "hogging off" than the rest of us! it would take literally 3 seconds to whack off .035 with a 36-40 grit Cubitron disk on an angle grinder or a disk sander. they cut very cool when new. that block with holes to dept +.005 is to keep from going too far, you could probably do it +.002-3 just fine too, with care.
 
QT Conrad [I love to grind. It's the easiest job in the shop if you know what you're doing, and seems to pay the best.]


So do I..Love to grind comes from being confident your set-up will hold, that you will not heat harm the part and that you can safely make size and spec with not going under.

That confidence can be made in a year or three..or ten.

Or never....

I have known old times who could grind with the best ..but still feared the job.
 








 
Back
Top