How much grinder do I need?

[Houndogforever]

Hey guys, I'm back.
I just bought this grinder off craigslist.

Norton 6x18 Surface Grinder - tools - by owner - sale

S/N 1952 H 5860 Height Under Head 8” Table Working Area 6” x 18” Wheel Capacity 8” Magnetic chuck 6”” x 18” Hydraulic Table Feeds Motor 1.5 Hp Voltage 220 – 440 3ph Full Splash guards DRO Z Axis...

portland.craigslist.org

I'm hoping this was a good choice. Seems pretty heavy / stout and has the digital readout too.

 

[michiganbuck]

Mostly non-CNC surface grinder's travels are called down, long, and cross
I suspect that you are referring to a DRO on the down feed.
Looks like a very decent grinder. Roller way I think. 1.5hp should be able to down-grind a 3/4" wheel pretty easy (Perhaps wider but 3/4 may be best). 3/4" wide so make two down grinds. incrementing down/ diamond skim and the incremental cross.
I do think you should try a chuck load right on the chuck because that is the most ridged way to grind, more accurate, and faster than loading a fixture..Use a rubber squeegee to wipe the wet chuck.
I would make a dresser with the diamond set at .474 if that is the side you are grinding. would grind it to perhaps +.002 or + .0015 skim the diamond and then incremental cross that to finish.
I think you said .475 to .470

*Agree, that you can incremental cross feed with a .006(or what) take, make a small dress(.001/,002, and then another incremental cross to finish size.
With 100piece runs, you can try both methods o see what you like best.

*One great time saver is using the set height diamond so you can hold .0002 (or so) without not removing a part to measure. You don't need to set the diamond to .00000 size...you just set it and then know after the first part that a .0002(or what) down feed after the dress will make the size, very often you can run all day on that diamond height setting. A surface grinder dial is a much better measuring device than a micrometer.

Getting the same job/part often you might make a diamond set gauge so as tofeel your wheel to at the start of the run. Or have a set of clunker JoBlocks, or save one part for a gauge

Wheel selection is perhaps related to your surface finish needs. likely 46-54-or 60 gt wheel (?). I have had jobs where an abrasive paper wipe/hone proved better productivity than using the next finer wheel.The time to wait on an automatic cross feed travel was used for a couple figure 8s and a straight wipe.

For+- .0005 or .474 / .473 you should not need to measure the parts, just run off the set diamond.

*What is your wheel ID..1 1/4"?

 

[Houndogforever]

It is a flat & Vee Way on the Long travel. I believe the wheel is 8" x 3/4 with a 1-1/4" ID.
It is hydraulic long travel and cross travel, but nothing automatic on Z-axis up and down.

I'm not sure I understand your comment about the diamond. I think you are saying mount a diamond dresser so it is the same height as my finished parts.
Then I can just move the table over, dress the wheel and move back to my pass location?

 

[Houndogforever]

So now that I own it. How do I use it? I mean, I will figure out how to make it go back and forth and such, but what do I need?
Obviously I bought it to grind D2 to a 16-32 finish.
What wheel do I need?
How fast should the table move back and forth when rough grinding? Or for Finish grinding.
How much cross step should I take. I've seen some machines that had .020" minimum step over, is that large or small?
How much depth of cut can I take?
Am I better off taking deeper cuts and shorter cross feed? Or take shallow cuts and big step overs?

 

[michiganbuck]

QT Op: (It is a flat & Vee Way on the Long travel. I believe the wheel is 8" x 3/4 with a 1-1/4" ID.)
That is good, flat and V machines are my favorite.
Basically, there are 3 ways to make size with a surface grinder
1. the slowest=Measure the Part, then take a guessed amount, measure and guess again and take another amount. and perhaps do that one more time. For a one-up part this is OK.,
2. Have a spotter (an adjustable one is best) micrometer it to set at the desired target , crank your down-feed to feel the spotter with the parked/dressed wheel and note that number, grind down to that dial number and skim grease pencil mark off the spotter and know you are at size (with little or no measuring individual parts or loads.
3. for a production job set a diamond to the desired height off the chuck, run one part to determine how much more down feed will make size. then you grind the next part to that dial number, skim the diamond and down dial the known amount (with little or no measuring individual parts or loads..

It may take a few times to master #3, to get used to raising the diamond to feel the wheel so to get .0005 .0002 (or what) setting, for the down dial after the dress..

The size-set-diamond should have a 15* or 20* tilt to the left and be set at the highest (most down center) place of the wheel.

It is very good to have a checking plate next to the surface grinder with a dial indicator set vertical at the part top face, this is more accurate and much faster than picking up a micrometer. With your part being tapered bottom your checking plate will use a bump rail uing a sample part for a gauge.. (6"x 12" x 5/8" is often a good size.)

Again: calling the down-feed Z on a manual surface grinder will just get you in a lifetime of stupid waste of time arguments with grinder hands all about the world.

 

[michiganbuck]

Good to have a maintenance manual for the machine.
If you decide to grind the chuck bring that subject to the PM.guys.

You might find a manual here (and sent them $20 or what for being there for you.)

Norton Co. - Publication Reprints | VintageMachinery.org

 

[stephen thomas]

Assuming flood coolant, through-the-wheel would be even better:

How much depth of cut can I take?

Depends on the machine and the material.
If you plunge grind on D2, i have trouble imagining more than .0005 down per pass. Maybe better .0003.

If you incremental feed, without looking back at you posts on page one, my memory is that tolerace is easy and depth is under .020; if you use Buck's method for dressing to size, you can take it all in one pass. And you won't have to to dress very often.

I suppose i should qualitfy that. If the grindier is grinding mostly parallel after the mill made the taper, the above is true. If the grinder is grinding the taper, you better do it in 2 passes with a heavy rough and a light finish. This is because on small grinders, the head does/can float a bit, so it will grind less at the end with the heavy cut, and more at the end with the shallow cut. Though even there, it will be more uniform with incremental than it would be with plunge.

Am I better off taking deeper cuts and shorter cross feed? Or take shallow cuts and big step overs?

You have to try both and see what you prefer. Shallow cuts and big step overs means you have to be standing working the grinder (without auto Y/downfeed) . It also means on D2 you might be dressing the wheel every pass or every couple passes.

As mentioned, i think you can take it all in one pass at your tolerance and spec, with incremental, and the finish will be shinier and more uniform. (So long as you have a good filter, and grind clean). You won't have to dress very often, but when necessary, it will require the entire wear step to come off the wheel. The wear step in the wheel will be the depth of your grind pass.

I would start with 46 J wheel, 8 or so porosity. More is better but you don't need induced porosity unless you are trying to grind dry (don't bother ) Buck has spec's on Radiac wheels that really hold their shape and grind aggressively yet cool. I found a source for NOS 7" 46J wheels from a recent but now obsolete mfg'r at $4 each and they are quite good, but not quite as good as the Radiacs or some old NOS Nortons. D2 might benefit from some of the doped wheels or even 5SG, but that is well out of my knowlege base. I use both, but my experience with the exotic wheels is not broad enough to make knowledgeable recommendations.

If you can find them, you might even try 36 J.

If your wheel gets used up too fast and the wear ledge quickly becomes a wear ramp, you could go harder on whatever hardness you start with. If the wheel burns at all (probably won't with controlled incremental infeed) or if the wear ledge does not develop at all and sort of rounds and stops cutting, go softer.

I'm sure Buck or Ed K will be able to correct me, listen to whatever they have to say first. Buck has helped me directly over the years, and reading Ed definitely improved a lot of my understanding and approach to various machining topics

smt

 

[eKretz]

I think maybe stephen is referring to me as Ed K; but really my name's Eric. The Ed thing from EG is a sort of inside joke,

Also, don't listen to anyone else first, stephen is perfectly well capable of giving great advice, as he demonstrated here. I'd say listen to everyone equally, try a few things for yourself and do what you find works best in your situation. That's how I've always done it anyway.

For myself, I prefer shallow cutting and large stepover if there's little material to be removed. I will do straight plunge grinding or heavier cut/small stepover if there's more material to come off, especially on a smaller grinder.

As far as table speed, my approach is to run as fast as able to run whenever possible. This helps to prevent burning as well as just plain gets the job done faster. You'll need to look out for wheel wear sometimes though. If the wheel is too soft and/or the material is too hard it can wear the wheel too rapidly, so you've got to slow down the table some, speed the wheel RPM up or switch to a harder wheel. There are lots of variables that all play off each other.

If you're new to grinding it would be a very good idea to grab a few older grinding texts and do some reading. Speaking for myself, I know a good bit about grinding but trying to recall all the pertinent info when typing up a message doesn't always work for me... My brain tends to recall that stuff on "autopilot" while I'm doing the work much better than when I'm typing messages, heh. It does help when Buck and stephen and others throw out advice too, that usually makes me recall more that I should have added in the first place.

 

[stephen thomas]

Eric, i apologize and will try to remember your correct name in the future.
Thanks for the nice words.

smt

 

[michiganbuck]

I was taught that deep sock removal and small cross-feed increments was the proper method,
Then with grinding flat form tools I was introduced to having the form crushed into the wheel and down grinding a few tenths or a few thousandths with every long travel pass.
Then I was introduced to a very small stock removal and large cross feed step overs.
Now I know that every job is different due to material, holding ability, performance needs, heat build-up, and horsepower needs. so there is a place for each kind of grinding.
A seasoned grinder should know all the methods and Not be in love with a single one as the only way to grind.
Stephen and Eric are quick to offer excellent grinding advice..and there are a good number of top grinder hands on PM who post little but know a lot.

YouTube is chancy..there are some posters there who give bad advice / Even a grinder company rep who gives poor advice.

One Youtube that any new guy , and most old grinder hands should watch

 

[Houndogforever]

Yeah, now that I think about it, down feed isn't Z axis at all. Z is thru the spindle.
I get that point, thanks.

Since there isn't any auto down feed, I would be terrified to attempt to move down .0005 between each pass.

The machine has both an original dust collector /filter and an add on coolant tank for wet grinding. It also came with some Trim brand semi synthetic grinding fluid, almost a full 5 gallon pail so that will probably be my first try.
It did come with two arbors also. That way I can have two wheels mounted and be able to switch them accurately.
Had a box of wheels, I'll figure those out eventually.
Do you have any "how to be a grinder" texts or books you recommend? I know how the machine works but wheel hardness, density and grit are all things I know minimal info.

After machining, I leave .005-.010 material, then heat treat. Theoretically then, my max depth of grind is .010. From what I think I'm understanding, I should start at finish dimension + .0004, take small cross steps, about .015-.020 ?????

Then spark out back across to where I started. Measure and examine finish.

If required, step down that final .0005 or less and step across again.
Should the light depth cuts have larger steps? How large?

 

[michiganbuck]

OT Op; (down feed isn't Z)

it might be Z , and it might be Y depending on who built the machine and what they wanted to call that axis...That is why it is best called Down (or verticle).

You could grind as you say and that should be fine.
Near full depth (- the .0004 you decided on for finishing) and then take small increments of cross feeds across the part at each long travel.
But don't pass/cross back over going the other way/direction as you may want the wheel lead-in to be the rougher and the wheel follow portion to be the finisher, going/crossing only one way allows that.. So taking about .007- .010 with this pass.

Long travel speed, start with what looks like a comfortable hand/manual speed

If ooo4 has proven to be an ok amount to allow finishing then that is fine also.

Good to make a spotter being a block the is the starting height / the first cross-over height with it having your chosen amount left for finishing, Yes, as the part is held in your fixture, including the +.0004 you decided on for the finish cross.
At the start of the run you bring your dressed wheel to hand rub that gauge with the dressed wheel and you know where to start/zero, even after you might have changed the wheel.
Set your checking plate to your master part to zero.
Grind the set of parts and then check them in your checking plate, notice where they are for size so you can learn the amount of wheel loss/break down for each set of parts /or few sets.
You might think/find that you may lose >0003 on every set so keep that in mind.
I like to have a tab if masking tape to attach to my down wheel so to see/remember the last set and the wheel break down.

Yes you will have to feel out all of thes this because the new gronder may act a little different than the old one.

The piece of tape on your down wheel is better than messing with your DOR for this kind of job..
You may find that you can grind one set per dressing or two sets (?).
Might find you need more than.0004 (or less).
Write stuff down so if the new guy gets the job he doesn't have to re-engineer the process.
Guess I would throw a set of parts back in the fixture in different places and put the fixture on the surface plate to discover how much error the fixture could have.

 

[michiganbuck]

And along with your grinding perhaps make an extra part and down grind it with .0001 and then more + more to see how much a 3/4 wheel might down-grind and still feel/be safe. Or just try down-grinding on some other part/material.

Yes, just so you know this method exists and for some work, it may be better than incremental cross grinding.

Mild steel you can go/grind blue blazes, and getting into harder steels you need to take less per long travel. but this, "down grinding" is a grinding method, so you should to know.

 

[michiganbuck]

You might have a height set diamond so to use instead of the wheel-feel-gauge with it set close to the operator position, so easy to dress without much traveling away from the work, and still safely away from the setup so little chance of an accidental bump into....

*Sorry for rattling on with this as there are other ways to run this job. Likely 4 top grinder hands would have 4 other procedures. This procedure is in conjunction with using your fixture.

 

[eKretz]

On a light finish downfeed I like to cross feed about ¼ - ⅓ the wheel width. For a heavier downfeed I will cut that back to .025" - .050" or sometimes even less on the cross. You just kind of have to feel it out depending on the wheel and other variables (wheel speed, table speed, depth of cut, how much material you're removing per wheel dressing, etc.)

 

[michiganbuck]

I think 1/4- 1/3 cross of a 3/4" wide wheel would be too much @ .010 take.
One might cross .030 for a 4 1/2" cross travel length at a .010 take, come back to start, and pull .0004 finish pass take.
That would equate to about 5 minutes per load plus setting parts in fixture time

4 1/2"cross @ ..020 crosses would be 225 long travels for each take (.010 and .0004) would not be so bad about 7 1/2 minutes. plus loading.

So parts might be a minute each with adding loading.

Reducing the take to .005 would be good for this job if possible (.005 + .0004 Finish)..
Finding just the right wheel and then the first pass might make finish spec.

Ref: fixture load width 3 1/2", wheel 3/4", safety 1/4" = 4 1/2" cross travel
9 or 10" long travel. estimate.

 

[michiganbuck]

The advantage of setting parts on a tapered parallel would be that your machine travel would be about 11" x 2 1/2" for 8 parts so cutting your grind surface area about 30%, reducing the setup time, and increasing accuracy, perhaps cutting time in half.
This would not be down-grinding, but would still be incremental crossing on a smaller area.

Down grinding would be even faster but would require a try to see if the machine HP is adequate to keep wheel RPM as needed, holding ability enough to secure the part, and heat gain reasonable.,.

QT OP: (Since there isn't any auto-down feed, I would be terrified to attempt to move down .0005 between each pass.)
At .0005 per pass Down Grinding would take 20 long travel passes to take .010, so not very much time.

This would not be a chancy setup, but for a chancy setup one might down feed only on the grind-side, so 40 passes... still way less than most other methods.

Needing two passes of a 3/4" wheel might better serve the limitations of the grinder's abilities, or the abilities of the holding method. This would also require 20 long travel passes.

I am not suggesting that the Op change his methood, I am simply explaning some various methods to run/grind the part.

 

[rogertoolmaker]

Yeah, I figured it would need to be a higher HP spindle - I was more wondering about whether that itty bitty spindle diameter on the small machines would be rigid/stiff enough for grinding that wide all at once. If there's an issue I suppose it might do better with something like a 3" or 4" diameter wheel I'd think, to get that force applied a little closer to spindle centerline. That'd help ease up the HP requirement too. Not sure how easy that wheel might be to find though... I've never actually tried to grind full width that wide on such a small machine.

 

[rogertoolmaker]

D2 and grinding heat. I doubt that grinding with the full width of the wheel is a good idea with D2. We need to be careful not burn D2. Getting it hot can develop microscopic surface cracks. Depending on the service the tool is to receive the cracks can grow with eventual failure. We're dealing with a high carbon high chrome tool steel.

 

[michiganbuck]

I have run plenty of surface grinders with 3/4 Hp and they did just fine with the wheel diameter that fits the RPM..and the stock removal that doesn't slow the RPM greatly. I have even done production rolled form grinding tool steels full wheeling wider wheels, you just down feed what the machine can handle..

3 or 4" (small) wheel does not give more power to the grind, when you get your Surface speed slow enough you begin honing, not grinding
Surface speed is what makes grinding work and in the rough ballpark of 5000sfpm is what you need, up to around 6000-6500 for vitrified wheels with watching out for the specified RPM on the wheel label (don't go over) . Getting much under 4000 and you are on the border of not having efficient grinding.
A 3" wheel at 3400 would be about 2500 sfpm.