Best orientation for grinding a faceplate?
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    Default Best orientation for grinding a faceplate?

    I want to true the chuck backing plate of my cylindrical grinder. This mounts in the workhead and holds a 130mm (5") grip-true chuck. My question, should I grind this with the workhead in the normal orientation (rotation axis pointing to tailstock) or should I rotate the workhead 90 degrees? In the first case I will be side-grinding with the wheel, in the second case I will be grinding on the normal front face of the wheel. I need to remove about 10 microns (0.0005") of material.
    Last edited by ballen; 06-17-2019 at 07:25 AM.

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    No direct experience but I feel that unless you were to relieve the side of the wheel to reduce contact you’re more likely to scorch the face plate and should use the periphery of the wheel instead.

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    Quote Originally Posted by Hazzert View Post
    No direct experience but I feel that unless you were to relieve the side of the wheel to reduce contact you’re more likely to scorch the face plate and should use the periphery of the wheel instead.
    Both sides of the wheel are dressed at an angle (about 1 degree) exactly for this reason. The wheel gets wider as you move away from the rotation axis towards the periphery.

    There are probably people here who have done this (both ways) hundreds of times. I'm hoping to hear from them.

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    Grinding with the O.D. of the wheel creates much less heat than grinding with the side of the wheel. Even relieved there is much greater wheel contact with the side than the periphery. Heat will be a problem with a 130 mm surface, and checking for flatness is even more of a challenge.

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    Hi Ballen, I suppose you've studied photos of similar articles freshly manufactured by reputable people? The finish will tell all. Thinking stuff like camlock lathe spindle faces, even chuck backplates as you are contemplating.

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    Ancient B&S literature for Universal grinding machine shows "work stock" rotated 90 degrees and normal periphery of wheel doing the work.

    ON EDIT

    It may not be immediately apparent, but at least on some machines, the "work stock" can be anywhere needed up and down the length of the table
    Attached Thumbnails Attached Thumbnails bs-face-grind.jpg  
    Last edited by johnoder; 06-18-2019 at 07:16 AM.

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    The face plate should made to be near dead flat and near dead true for run out, the wheel need be easy to dress during the operation. I have done both ways. Checking flat perhaps with blue-in to a known flat something.

    The wheel OD is more rigid as to the spindle and the wheel itself so if having a compound base for easy swing to 90* I would swing and use the wheel od.

    Side wheel grinding seemingly easier because the machine is already there and so would make a cross-hath grind with using an under-cut wheel with only perhaps 1/8 side grinding face and dressed to that flat (not just dished). This is fine but harder to set-up and as the load increases with more part engaged, the the stress to the wheel increases.

    One or the other you need swing and tilt to make it right. Tilt might be done with using a shim under the work head. The holding taper ID and OD bug free and clean, a locator mark on the work-head and taper so to be place the same 180 spot at every use. The chuck and any fixtures used also having a line up mark so able to take off and replace not a loss of true.

    I like to swing so using the wheel OD in most cases. This for a more solid grind and moving to dress easy. Agree with only .0005 (take) additional dress may not be needed.

    In a shop having a number of machines an arbor or device ground in to one machine or work head would not run true on another machine, so should be numbered for only that machine if needing very close parts. Even brand new machines and new arbors would be way off for close work. Perhaps a tenth or two off in the machine taper and then a tenth or two off in the arbor face and another in the arbor taper would make close work impossible.

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    I had a friend who set a magnetic face plate chuck on his OD-ID grinder work-head. On the mag chuck he would place a 3jaw chuck, a dead or live center, a V block and yes just about any fixture needed for some common or odd part.

    He used to bring a part to me for me to make up some chucked or centered arbor
    for grinding it, likely because I was quick at one-ups and had a bucket of old obsolete stubs that were handy for such.

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    If you want to grind the shoulder too set the wheel at a 45Dgr angle and dress a 90Dgr angle on it
    Keep in mind you do not get a sharp corner
    If you grind with the side of the wheel you better have a relief at the end near the corner at the shoulder
    The stone will wear at the corner

    Peter

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    Hi Peter,

    Thanks for the advice. I'm going to grind with the OD/face of the wheel, not with the side.

    The chuck has a small bevel (maybe 0.3mm wide) where it fits over the step in the backplate. So I only have to get within 0.1mm of the step, which is easy on the grinder.

    Before grinding it, I could also put the backplate on a lathe and cut a 0.5mm wide 0.5mm deep relief at the inside corner of the step. Any reason NOT to do this? Seems like it would make everything else easier.
    Last edited by ballen; 06-19-2019 at 12:00 AM.

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    If it is a metric made machine .5 would be suitable/OK.

    But if an imperial machine then you should make that corner relief .020".

    QE: [with the OD of the wheel, not with the face.]

    We called the OD of a type 1 wheel the face and the flat part the side.

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    Quote Originally Posted by michiganbuck View Post
    If it is a metric made machine .5 would be suitable/OK. But if an imperial machine then you should make that corner relief .020".


    We called the OD of a type 1 wheel the face and the flat part the side.
    Sorry, my bad, I have corrected my post.

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    Background to comment #5 is recollection that the 1986 Schaublin 125 camlock spindle nose had cross-hatch finish & even the work face of the 240mm faceplate had similar. Currently having the same mental wrestle myself .. have to grind a couple of thou off the face of my lathe's camlock spindle nose. I originally did it with the periphery of the wheel using TPG on the lathe in question but being green did not take quite enough off, cone & face giving the SAME degree of contact on manual presentation i.e. no squeeze on the cone. Learning of my mistake thro' this forum intend to correct but the dilemma .. periphery of a disc wheel or face of a cup? Leaning toward the former (as before) but Schaublin ...

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    Quote Originally Posted by swarfless View Post
    Learning of my mistake thro' this forum intend to correct but the dilemma .. periphery of a disc wheel or face of a cup? Leaning toward the former (as before) but Schaublin ...
    My backplate is a low-value part. Provided that I avoid the register step, there is plenty of meat there. So if I screw it up, I can try again (and again).

    Your part, a Schaublin spindle nose, that's another world entirely. I suggest you start a new thread about it with a photo or two and ask for advice. Some of the guys here have a lifetime of experience, meaning that they have made lots mistakes and can help you avoid those.

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    Didn't mean to mislead, my lathe is not a Schaublin but because I spent a fair amount of time on one in a former life I tend to use Schaublin's methods as a benchmark. Mine is but a humble Colchester Chipmaster. I CAN tell you that the result from grinding with the OD of a plain wheel was fine,even using a TPG, the only fault was my failure to appreciate the functional requirements of the spindle nose. At the time I thought the bearing blue print was perfect.Ignorance is bliss.

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    I ground three backplates yesterday. Here is an action shot, you can see that I'm getting contact on about half of the area to be ground (where there is no blue marker left). As desired there is no contact on the inner step past the relief that I turned. Setup took a long time because I first had to make a stop for the longitudinal travel and second had to turn the reliefs into the backplates (which required making an MT5 holder for my lathe). I aligned the headstock by clocking a point on one side of the backplate, then rotating the backplate 180 degrees and clocking the same point on the other side.

    Final result is flat and repeats to about 3 microns (0.0001") when I remove it and replace it in the taper.



    Final result. You can see the blue marker in the shallow relief and if you look closely, you can also see it on the OD of the step. That step is a precise fit into the back of the chuck so I took pains not to touch it.



    Buck, I used a fine wheel on the dremel to mark inside one of the drive dogs on the spindle with matching marks on the faceplates. So they can go back in the same orientation.
    Last edited by ballen; 07-01-2019 at 09:39 AM.

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    QT ; [ I first had to make a stop for the longitudinal travel ] Good they will be handy in the future.


    Looks great. Also know you can fab-up a reach bar assembly that can include holding a lathe tool bit or a parting tool or even a Dremel, and so make shaper function on most any machine. So, with this your grinder can make decent/professional calibration or degree lines on an OD or face of a part. (½ x 1 ½” bar stock is often stout enough for this task.)

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    Quote Originally Posted by michiganbuck View Post
    So, with this your grinder can make decent/professional calibration or degree lines on an OD or face of a part.
    This sounds like something I could use. But I don't understand how it works or goes together. Could you provide a sketch or photo or a more detailed description? I have a dremel and some engraving v-form bits. Would be nice to make up something that uses those to make dividing marks on round parts. Also not sure how to do the indexing on my cylindrical grinder.

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    Just a fixture (set of bars) to hold a cutting blade and using your manual hand travel to make it go to and fro. Could go from some place on your grinder wheel head/ from the wheel guard of a heavy duty surface grinder. Just about any mechanical device being stout enough to push a blade for .002 or so cuts to make a line. Even a horizontal blade mounted in a lathe tool holder and using long-bed travel or cross feed to push that blade. Same to hold a Dremel with a 1/32 parting wheel makes a very nice line. Most every joint in this would have perhaps two 3/8 -16 or the like (or better) bolts at every joining. Yes just cutting in mild steel or brass. Yes you have to figure out the indexing for each project. Eye-ball can get about .002 / .003."


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