Surface Grinder table speed
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  1. #1
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    Default Surface Grinder table speed

    I have a Chevalier fsg-1224ad surface grinder with hydraulic table feed and automatic cross and downfeed.

    I have been grinding only some steel for now and it seems that when i take the last few 0.0004" passes and run it with high table speed, i get better surface finish.

    Im new to grinding and im asking for your help!

    How to determine the right table feed speed?

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    By sight and sound. You will know quickly if you have it wrong!

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    It all depends on the type of steel (or any material) and it’s heat treated condition, whether it’s possibly annealed for fully hardened will have a massive impact on how it grinds. Also your type of wheel you are using, the wheels surface condition and also the size of wheel will have a impact of surface speed of grinding.

    Your table feed will have a smaller effect on surface finish compared to many other factors described above.

    Factors such as spindle condition, use of coolant and depth of cuts will have a greater effect.

    The table fees is more of a feel rather then a definitive calculation,

    ** it may be more of numerical factor in more specialised modern grinding machines but nothing I’ve ever come across**

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    Suburban tool has many good videos on grinding that should help you out.

    YouTube

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    The sparks can sometimes tell when running dry..when they seem to become a solid bar you may be going too fast. Running wet a noticeable slowing of spindle RPM is a dead give away.
    A change in sparks pattern, getting close together or changing color indicates part getting hot and may soon suck up into the wheel and burn so a slow down or better yet a pause off part.
    Parts sliding to the left direction a good hint. Parts flying off the chuck too fast and too late.

    So sound and sparks are the basic premise of too much travel speed.

    Re:Parts flying off the chuck can often be avoided with a bump-stop high on the go-side of the taller part, a block of steel, an angle plate, a double clamped finger from a steel block.. If you can tip over a high part with a two finger push it may a tip-over and go flying set-up. If a bump-stop is not square it may not be touching the part high-up so not very good... so the bump-stop can be turned 180* so it might bump high, or a shim can be place high on the go side
    Last edited by michiganbuck; 06-09-2019 at 06:16 AM.

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    Try the guys on Solid Rock Machine on YouTube. He has some good info on accurate grinding and surface finish.

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    Thanks majohnson I just check out one of his (solid Rock) YouTubes..

    Good that he talks in millionths, every grinder worth his salt should talk in millionths.
    Good that he tells about part swell-up when roughing a part, and how the finish skim shows the swelling from heat.

    One thing few mention is when you get to less than 50 millionths it is often better/good to hone the part to finish to size or squareness. it is just like scraping because you take/hone from the high and then lap a little to make your part near zero.. This is because you next set-up may be 50 millionths the other way. Mostly 6 to 12 millionths is close enough for your master angle plate and master V block.

    Having masters .0002 off makes it hard to run good parts to less than .0004/.0005.

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    I totally agree with above comments that it is more of a "feel" thing, and the right answer in one case, with a particular machine, wheel, dress, use of coolant, depth of cut, ect., may not work in another case with different factors.

    BUT, having said that, it's often helpful to have at least a starting point as to what a reasonable work speed would be, especially when new to grinding in general, or grinding something out of your "comfort zone".
    I've used the recommended surface feet per minute for machining a given material in it's annealed condition with HSS as a starting point.
    For example, I'd start grinding tool steel at around 40-60 ft./min. So, on a surface grinder, if my table has a 12" stroke, I'd start about a second and a half between reversals.
    If I had a 24" dia. part in an OD grinder, I'd be looking for about 8 RPM of the work head.
    Again, these numbers only give you a reasonable place to start.


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