Surface Grinding Technique for Dummies
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    Default Surface Grinding Technique for Dummies

    I'm sure this has been covered extensively before, but after much searching, I figured I would just ask:

    How do you start a grind?

    Let's assume we have something like a 5x5x1.6" block of steel mounted on our magnetic chuck. I want to take it down to 1.5" thick.

    I dress my wheel (let's say for the sake of argument that it's 1/2x7) and I'm ready to start surface grinding.

    Do I....

    Start somewhere inside the edge of the block and work my way out to one edge and back to the other? I'm assuming that this way (granted that the block is already mostly parallel) I'm using the full cutting width of the wheel initially, until I come off of the edge of the block and start working my way back... correct?

    OR

    Do I start with my wheel outside of the block of steel completely, and start working my way in from the outer edge, using just the corner of the wheel at first?


    Now the reason I'm including dimensions is simply that I don't know what I do not know... I'm not sure if certain grinding applications/techniques are determined by how much your're grinding or needing to take away, so I figured that setting a specific scenario may yield more specific information...

    Thanks in advance!

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    To name a few:
    You can travel (right / left as incrementally down feeding) to just touch.
    You can down feed (or in feed) feed with wheel turned by hand only to just touch (feel) the work.
    You can keep a roll of masking tape handy and put a piece on the work to first intersect the wheel.
    You can use a grease marker to paint a mark on the work.
    With all you try to set zero (start position) and lift wheel to miss part or any high areas and come in safely.

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    Method is dependent on power(to retain RPM), wheel selection and work material.

    With a having enough power and proper wheel for the material you can dress bottom, come down to just touch( zero start), Then grind coming incrementally down-feeding as you pass left and right and using entire wheel bottom surface, this method is best served with using coolant and a pause or longer skip at the end of right left travel to reduce the generation of heat.

    The other method equally efficient is to touch for part height. Move off the work. Down feed an amount and as you table travel right and left travel come into the work with in and out hand wheel. This method sometimes (not always) gives better finish.

    The down feed method is the fastest if you have enough power to remove stock and still retain RPM and then with a dress, measure and cool before finish pass (s) gives good finish and size.

    With down feed finishing by taking a very small amount with fresh dress and one or a few passes gives a very good finish.

    A trick with this method (when dry grinding) for final finish is to grease the part with each pass to give less restance and get an even better finish.

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    The peripheral (OD) of the wheel offers the strongest transmission of rigidity of the wheel, spindle and machine. When it can be used the sock removal speed is increased.

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    Michiganbuck has gave you a ton of useful info here,

    First off...grinding .100" off is quite hefty and i wouldnt take it all off one side unles you had stable material and its already hard. Even still, i would probably split it up and grind .05" a side.
    If i were you, i would mill it off to maximum, leaving .01, but if your decent on a mill leaving .003 per side is plenty.

    After you dress bottom of wheel, use a piece of norbide to relive the side of your wheel a bit

    I would touch off botom of wheel to top of stock, wheel off the part in the Y direction, then wheel your z down .045", almost full depth, and begin SLOWLY coming accross, grinding primarily with the side of your wheel. pay attention to the finesse at which you are moving the X direction. You wanna stay smooth. And keep the wheel on the part the entire time.Dont ever let it come allll the way off.
    Dress bottom of wheel again, and being your finish passes on side one.

    Repeat steps for side two.

    Now this full depth method is super butcher...Grinders are not hogging machines, so dont be surprised if an old timer shakes his head at you or asks what th f*** are you doing. The bearings in the spindle are not meant to be used like this, so its best to have a beater machine for doing things like taking off .045 in a single pass.

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    I suppose I should clarify my initial specs, in that I wouldn't expect to take .100 (or even .045,.050) all at once, but your answers have given me much more insight.

    I guess I should have phrased my question thusly:

    If I only have to take, say .001 off of each side of a piece of flat stock, how then should I approach?

    I've read that infeeding (Y direction correct?) .050" at a time uses only the outer .050" of the wheel, at least until it starts wearing toward the center of the wheel.

    How would this be affected if I were to downfeed (z axis?) into the middle of my part? Is it more beneficial to "kiss" the part (or a piece of masking tape), than raise the wheel a bit, infeed to the outer edge of the piece and come back down on it, so that I start on the outer edge of the wheel?

    Hopefully my question makes sense...

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    Quote Originally Posted by ARCustomKnives View Post
    I suppose I should clarify my initial specs, in that I wouldn't expect to take .100 (or even .045,.050) all at once, but your answers have given me much more insight.

    I guess I should have phrased my question thusly:

    If I only have to take, say .001 off of each side of a piece of flat stock, how then should I approach?

    I've read that infeeding (Y direction correct?) .050" at a time uses only the outer .050" of the wheel, at least until it starts wearing toward the center of the wheel.

    How would this be affected if I were to downfeed (z axis?) into the middle of my part? Is it more beneficial to "kiss" the part (or a piece of masking tape), than raise the wheel a bit, infeed to the outer edge of the piece and come back down on it, so that I start on the outer edge of the wheel?

    Hopefully my question makes sense...
    I personally have never ground a flat piece as you have described..

    Leaving a thou to grind...i would put a nice fine dress on the wheel, depending on your tolerance, touch off on top, dial down .0007, starting off the part, feed over in the Y, come all the way off the part, dial down .0001, dial back accross, then make a spring pass back one more time. as far as how much do i feed accross, i usually turn the hand wheel 1/4-1/3 of a rev. just keep it smooth and consistant.

    if your holding .00005 tolerances your going to want to check the part vigorously prior to you finish pass.

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    Forget all that stuff above. First go to the mill and square it up or whatever and leave just enough to clean up. That will more like .010 than .100. if you are using the chuck for workholding then the sides are apparently (or will be) parallel. After dressing the wheel move over the part on the chuck. If you are not confident on your touching off then place a piece of paper on the part. Wet paper will stick and not be blown away by the wheel wash or you can hold a strip of dry paper. Come down til you just touch the paper. Now you are .001-.002 away from the work IN THAT SPOT. Since the work may not be perfectly flat and parallel that may not be the highest spot. Move over the work end to end and side to side slowly to see if there is a higher spot. If so, feel it out. If it is one or two thou then start grinding. Start from one edge and cross the part crossfeeding about .050 to start. If that is comfortable then maybe up it to .075. This is a matter of technique. When you reach the other side go all the way off and feed down .001-.002. Come back across just like before. When you have a cleanup then assess the finish. If it's good enough, fine. If not dress and take about .0005 or so and spark out. Now traverse to one side and set a stop. Turn off the chuck, remove part and clean the chuck. Place the part back on, ground side down. Turn the chuck on, release the stop, and you are ready to grind, no touch off required. Repeat as above to a cleanup and then go to your size.
    At this point it's time to get the axes straight. The traverse (side to side as you face the machine) is X. The downfeed is Y. The crossfeed is Z.

    Some previous posters have recommended various versions of "plunge" grinding. This feed down with out moving across. It has it's place, like slots and form grinding. It produces a lot of heat and shitty finish and then you have to grind it as above to get a decent finish. The heat will make it hard to hold size and tool room size machines do not really have the power and rigidity to do it.

    Grinding machines are not meant for heavy stock removal. If you use one that way it won't be capable of what it was intended to do, which is produce precision finishes and dimensions. It's a case of "just because you can, doesn't mean you should".
    Work safely.

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    Quote Originally Posted by ARCustomKnives View Post
    I suppose I should clarify my initial specs, in that I wouldn't expect to take .100 (or even .045,.050) all at once, but your answers have given me much more insight.

    I guess I should have phrased my question thusly:

    If I only have to take, say .001 off of each side of a piece of flat stock, how then should I approach?

    I've read that infeeding (Y direction correct?) .050" at a time uses only the outer .050" of the wheel, at least until it starts wearing toward the center of the wheel.

    How would this be affected if I were to downfeed (z axis?) into the middle of my part? Is it more beneficial to "kiss" the part (or a piece of masking tape), than raise the wheel a bit, infeed to the outer edge of the piece and come back down on it, so that I start on the outer edge of the wheel?

    Hopefully my question makes sense...
    Just touching off will not affect size appreciably.

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    Quote Originally Posted by tdmidget View Post
    Just touching off will not affect size appreciably.
    Im petty sure that would depend on the tolerance your trying to hold and how gingerly you touch

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    I have a 5 x 10, 1/2hp SG 50 years + old. For a rough finish you can grind .010-.015, if I do this I brush oil on the surface, each pass would be a Y advance of .050, sometimes depending of material .100 in Y. I recently had a coiled flat spring .125 X 1.5" and needed to take off.250. and .015 was the max it would take. For finish pass .0005 with a step of .025, leaves a nice enough finish, without killing my arms with the cranking.

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    I often use both methods to:
    1. Increment feeding across with y axis. 2. To down feed OD with full wheel contact while moving accross right and left with off the part at both ends.

    For .001 or .050 you may use either or both. Perhaps down feed only with table passing for .045 to .048 then dress and cross feed for final finish or dress and down feed the final finish.

    With a chunky piece of softer material I might down feed with OD taking a very heavy cut that does not chance loosing the part or slow RPM for fastest stock removal.

    The down feeding OD (with moving table right and left) is the fastest way to remove stock but requires enough power and a wheel soft enough to stay sharp.

    You should try both methods on a piece of hard and soft practice material to get a feel for various techniques.
    The surface grinder’s ability should not be limited by forming hard and set habits as each material, size of machine, wheel type and selection, set-up, fixture or magnetic holding ability and job requirement may need a certain finesse to be completed in a safe and efficient manner.

    The flip the part for even side stock removal is most important for certain materials and a good practice on all materials.

    Three important aspects of grinding are to make set ups and use feed rates that will not slow the RPM, flip and fly the part or chance breaking the wheel.

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    Wow... you guys are an absolute wealth of much appreciated information!

    Just to give a little background on what I'm doing and using:

    I have a Reid 618p surface grinder. It has power crossfeed and power traverse. My applications will mainly be in knife making.

    For fixed blades, I typically just need to remove scale from the heat treating process. Tolerances aren't too tight, unless I'm slotting a guard. Since I don't make a lot of knives with gaurds, I usually just clean things up on a belt grinder until both sides are relatively flat and shiny. The closer to parallel I can get things initialy, usually the better of I'll be, though I usually grind a minor taper into the blade anyhow.

    When I start getting into folding knives, that's where tolerances of .001 or better will start to be appreciable.

    I buy most of my flat stock in the .125 or .090 range. Typically, I shouldn't have to deal with stock removal of more than .005 or .010 at the most.

    I am in the process of trying to narrow down some light grinding pattern, though I think a lot of it could be attributed to my wheel hub, as well as the fact that I'm running dry (I lightly mist the parts on occasion.) I hope to change both the hub and my lack of coolant soon, however.

    It may also be a factor that my diamond nib is rounded over. I'm not sure, but I just got a new nib and will be testing this soon.

    Eliminating all of those variables is pointless, however, if I'm grinding the piece all wrong, so I greatly appreciate all of the pointers and valuable info given thus far.

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    Quote Originally Posted by ARCustomKnives View Post
    Wow... you guys are an absolute wealth of much appreciated information!

    Just to give a little background on what I'm doing and using:

    I have a Reid 618p surface grinder. It has power crossfeed and power traverse. My applications will mainly be in knife making.

    For fixed blades, I typically just need to remove scale from the heat treating process. Tolerances aren't too tight, unless I'm slotting a guard. Since I don't make a lot of knives with gaurds, I usually just clean things up on a belt grinder until both sides are relatively flat and shiny. The closer to parallel I can get things initialy, usually the better of I'll be, though I usually grind a minor taper into the blade anyhow.

    When I start getting into folding knives, that's where tolerances of .001 or better will start to be appreciable.

    I buy most of my flat stock in the .125 or .090 range. Typically, I shouldn't have to deal with stock removal of more than .005 or .010 at the most.

    I am in the process of trying to narrow down some light grinding pattern, though I think a lot of it could be attributed to my wheel hub, as well as the fact that I'm running dry (I lightly mist the parts on occasion.) I hope to change both the hub and my lack of coolant soon, however.

    It may also be a factor that my diamond nib is rounded over. I'm not sure, but I just got a new nib and will be testing this soon.

    Eliminating all of those variables is pointless, however, if I'm grinding the piece all wrong, so I greatly appreciate all of the pointers and valuable info given thus far.
    Trying to find you on the world wide web...I love a good blade, i carry an over priced ontario xm-1. would love to see your product. Also, ever though of throwing a picatinny rail on a fixed blade? I keep thinking to throw something together for my AR.

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    To avoid confusion or doubt, if you plunge into the work so that you're cutting with the entire width of the wheel, you're putting a lot more load on the grinder and wearing the wheel more than if you take a deeper cut and take smaller widths in the Z (front-back) direction. So with a 6x18" (or my 8x24"), the latter technique can remove stock a lot faster and need less wheel dressings. That's just roughing though.


    With respect to the surface finish problems in the other thread, the above isn't really significant, since a final pass at 0.0002-5" with another spark-out pass will remove the marks from the previous cuts. If you're still getting patterns on the work at that point, even after dressing the wheel as best you can, try cheating with a few strokes of 800 grit SiC paper or a Cratex wheel in the desired direction. The marks are probably far more shallow than their appearance suggests.

    Don't worry too much about how sharp the dressing diamond is. A sharp point and a fast dress allows for a fast cutting wheel with a coarser, "wire brush" type finish. A blunter tip or a slower dress allows for a slower cutting wheel and a finer finish. In my humble experience, too fine a point on the diamond will get knocked off pretty quickly.

    Last edited by Mark Rand; 07-29-2013 at 04:11 PM. Reason: Many, many Typos...

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    Quote Originally Posted by allloutmx View Post
    Trying to find you on the world wide web...I love a good blade, i carry an over priced ontario xm-1. would love to see your product. Also, ever though of throwing a picatinny rail on a fixed blade? I keep thinking to throw something together for my AR.
    I don't yet have a website, but I post most of my work on my YouTube channel:

    ARCustomKnives's channel - YouTube

    I'd like to start posting some more "in depth" videos of my projects eventually, but I've been too busy trying to get my tools set up and orders out the door... hahah

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    Mark if you are talking about my post I don’t suggest to plunge into the work.

    I am saying that in some cases one can down feed and then cross the whole work with the full face bottom of the wheel. For example you might have a 1/2inch wide part and a 3/4inch wide wheel. Or you might have a 2 inch wide part and a ¾ wide wheel to then down feed in three lines to the part.

    You are very correct that this puts a lot more load on the grinder motor,wheel, table and holding ability...
    And, yes the wheel wear will not leave a smooth final finish on the part so re-dressing and cooling may be needed before finish pass for size or surface finish.

    It depends on the hardness of the work (soft work is best) and having secure holding power of the magnet or fixture. Yes it might be faster to mill a soft part but that would require two set-ups not one.
    If you needed .100 removed and then a + /- .001 or .0005 size with a grind surface finish the one set up on the grinder would be much faster than two set-ups with grinder and mill.

    The wheel is much stronger with work forces to the OD. For the heaviest cuts the down feed is best done only on the left side to go to the wheel rotation and avoid climb grinding or smacking the work to pull it under.
    I don’t recommend doing this all the time but in some cases one can cut job time in half with this kind of grinding.

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    I wasn't too much worried about the wheel, but I do tend to run the motor to it's limits when grinding (due to the milling machine still being a work in progress), so I tend to work for the most metal removal for the HP on the grinder and I've a feeling that 20 thou down and 20 thou across is better then 1 thou down and 400 thou across, if you see what I mean.

    regards
    Mark

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    A couple comments:

    Mill scale, even the light golden haze on hardened A-2, will glaze a wheel faster than you can say it. I normally rough grind parts before heat treat, so I'm confident they are flat and parallel within the amount they can be expected to warp and swell, so after I've touched off, I try to grind the first pass deep enough to remove all the scale in one pass, if possible. I'll usually flip, and do the second side as well, then dress the wheel before I start grinding for finish size.

    I do most my grinding dry, but this same applies to grinding with coolant if the pass is heavy enough... If you finish a pass and on the next pass it acts like the part has a hump in the middle (your nice yellow shower of sparks turns dull orange and the drag on the table increases) you've put too much heat into the part. The technical term for this (besides "Oh, crap!") is that the work is being "sucked up" into the wheel, but in reality what is happening is the steel is expanding in the spot under the wheel and forcing upward, which is making the wheel cut more, adding more heat, which makes the steel expand more... you get the idea. This is bad, and can result in the part leaving the chuck. Normally you can see this start a few passes before you're in trouble; that's time to stop grinding, go to the can, get a cup of coffee, and then come back to it. You'll likely have to dress the wheel again since it glazed from the heavy grind, and you'll be amazed how many passes it takes before you are grinding the full surface again.

    Always keep in mind, heat is the enemy while grinding.

    Dennis

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    ARC You are asking general surface grinder questions and we are trying to give good general answers.

    Perhaps you and we should be more specific.

    (Do get a wheel mount that blue marks both front and back for a no wobble fit and not loose at the back side.)

    *After the chuck is true and you have practiced grinding some flat scrap stock to be very sure you have developed the feel for surface grinding proceed to grinding real parts.

    It looks like you will be mostly grinding the sides of work about 1 ½ wide and perhaps .150 thick.

    I would fabricating a diamond dresser to dress the wheel that would be set on the right side at center line with the wheel about .200 off the chuck with the blade being ground on the chuck, *but with you being a new-bee to grinding I will not recommend that for safety sake.

    You should first (wet) grind a part blocked in to the back and slide direction and set flat on the chuck to see how that works. A 46 grit perhaps a I, j or k hardness aluminum oxide (white wheel). Start some place (with a name brand wheel) and with the using same brand go harder/ softer until you find best for the job, using conventional Z axis (cross feed) incremental feed to the back rail in order to better hold the part.

    After you find wheel and method that works you might try a magnetic parallel about 1 inch high 3 inches wide and 8 inches long to set the blade upon(set on the chuck). Then having two steel parallels 1.100 tall, one 1.100 x 2 x 3 for an end stop at slide side (to the left) and one 1.100 x 2” x 8” inches long for a back rail stop.( that will be for a 8” or shorter knife blade).

    The rough knife blade would set upon the magnetic parallel to be side ground one side then flip to grind the other side. Having the knife blade held 1 inch (plus stock ) high allows a 1.100 (or so) high diamond dresser to be in a position (on the chuck) that allows very little up and down movement to dress the wheel adding both speed and safety to the job.

    Then grind wet using conventional Z axis (cross feed) incremental feed with testing various down feed set amounts and cross incremental feeds amounts and speed until you find the best for the job.

    If heat-treat has cause a out of flat condition having a set of various shim sizes might be needed to set blade flat and ridged for first side grind if absolute flat is required. Without stress relief flip/flop grinding may be required to keep or make the part flat. Often when grinding out of flat parts sucking the part down flat and grinding opposite side does not take out the out of flat condition, that is when shimming and flip/flop is needed.

    To test another procedure: (test on scrap knife only.)
    You might measure the wheel guard to see if a 1 ½ wide grinding wheel would fit. It so then you might try a recessed to one side 1 ½ wide wheel to try full bottom grinding. A softer wheel perhaps a 46h aluminum oxide (white wheel) would be best.

    Flood wet grind for full wheel grinding with using very small increment down feed then take a .001 or .002 diamond dress and grind finish first side then flip part to grind the other side doing the same.

    *Most likely full wheel grinding will not work in this application and cause work to swell up and then burn, still it is worth one try. If It fails then go back to conventional Z axis (cross feed) incremental feed.

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