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Poor Man's Surface Grinder

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  • Poor Man's Surface Grinder

    Anyone tried using a modified radial arm saw for a surface grinder? Something needs to be done to keep the dust out of the motor, but for clean up work it seems like it might be feasible, and in the realm of home shop machinery solutions. I'm curious because I just picked up an older Delta Super 900 saw in utterly excellent shape for $40.00. An example is shown here: http://www.owwm.com/photoindex/detail.aspx?id=3825

    What a great site that is for older woodworking machine information!

  • #2
    I have three radial arms at the moment,everything from a 10" Sears to a 16"Dewalt.I have used them for saw blade grinding,but I don't think they would do to well for surface grinding.

    The saws frames even the big monsters like my Dewalt are pretty limber.I haven't checked but my gut feeling is that there is atleast .005" deflection from just the weight of the saw head moving over the arm.Since .001" is a fair pass on a surface grinder I think t would be a waste of time trying unless you made serious mods to the saw.

    Something like an arm support to tie the end of the arm to the base would be a start,but even then.

    Next problem would be the track bearings,they aren't that great,usually a fair amount of slack up and down too.

    The one I used for kiss grinding saw teeth worked because it only needed to hit one small spot in the same location time after time.Trying to maintain any kind of accuracy over say 16" would be difficult on RAS.Over 4 or 6" might be doable to some degree of accuracy.
    I just need one more tool,just one!

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    • #3
      In addition to the (relatively) lousy bearings and the deflection, I suspect there would also be far too much vibration to get any kind of decent finish.
      ----------
      Try to make a living, not a killing. -- Utah Phillips
      Don't believe everything you know. -- Bumper sticker
      Everybody is ignorant, only on different subjects. -- Will Rogers
      There are lots of people who mistake their imagination for their memory. - Josh Billings
      Law of Logical Argument - Anything is possible if you don't know what you are talking about.
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      • #4
        Build a swing grinder from a cheap import drill press instead. It's on my list of things to do, still...

        Free software for calculating bolt circles and similar: Click Here

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        • #5
          Evan I seem to remember asking this before,but couldnt with the correct fitting a milling machine be used as a tempoary surface grinder.I should think this would work better than a r.a.s. as it is beefier and stiffer especially with power feed???Alistair
          Please excuse my typing as I have a form of parkinsons disease

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          • #6
            I've got that same Delta saw.... (I paid $50 for mine) found at a garage sale maybe 10-12 yrs ago mounted to a most "robust" bench (read: "overkill construction") , figured the bench was worth close to that. Turns out the bench was about all I got out of it, the saw is badly underpowered. Would do trim stuff, but put a 2x6 in it and it couldnt handle it. Have you tried yours yet Dennis? Does it seem underpowered? I lean to thinking that my motor is bad, but having no more in it than I did, I have just shoved it back in a corner and try to ignore it .... I did put that bad-boy bench to good use!

            FWIW ... I would have doubts that a radial saw would do much as a surface grinder, for the same reasons already mentioned, marginal bearings and flex in the arm ---- course, it'd be simple enough to give it a quick test, one of the thin wheels should mount with out any mods, cobble a magnet and try out on some scrap----
            If everything seems to be going well, you have obviously overlooked something........

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            • #7
              Hsm magazine did an article on this topic many years ago and the results were less than bad.

              Evan, I have seen these swing grinders before but was told that they were very dangerous, grabbing the work and throwing it at you if you had to much of a cut, if this is not the case or the chance of this is rare if used properly could you do a little write up on them, it looks like a good solution to the at home "low use" grinding needs.
              The shortest distance between two points is a circle of infinite diameter.

              Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

              Southwestern Ontario. Canada

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              • #8
                A few years ago I purchased a Sears radial arm saw for work. I tried to set it up, per the manual and had a lot of trouble. None of the adjustments held - and I am talking 1/16s and 1/8s inch deviations, not thousanths. I noticed I was moving it around on the floor to more easily reach the various adjustments and a quick check revieled that each one changed with even a small such movement.

                I made some floor mounts and bolted it SOLIDLY to the cement floor. Made sure everything was very tight on the mounts. Then did the adjustments one more time. Everything held perfectly. First try. And it has held for at least 5 years now.

                They could have saved me six hours of work if they had been up front about the lousy stand. Radial arm saws have a bad rep among carpenters and you will almost never see one in a cabinet maker's shop. This is apparently why.

                I like Evan's idea better, but if you want to use a radial arm saw, I would add an X-Y table and lock the arm down for use. Extra bracing (fixed) on the arm would also be a very good idea. But I suspect you will still have problems.
                Paul A.
                SE Texas

                Make it fit.
                You can't win and there IS a penalty for trying!

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                • #9
                  I don't have any experience using a swing grinder but they are common as low wages in the foundry business. They use ones that are suspended from chains, arms, booms or stands and use them to grind off flash etc. John S sent me this picture and I think with proper care and some guarding to prevent the work shifting toward the operator it would be reasonably safe. I sure don't like the idea of using a radial arm saw. I have a 10" Sears made about 30 years ago and that tool scares me almost as much as a chainsaw, maybe more.
                  Free software for calculating bolt circles and similar: Click Here

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                  • #10
                    Just mount a vice on the table of the swing grinder. That is how punch grinders are set up.
                    North Central Arkansas

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                    • #11
                      I have a magnetic vise that I use on my mill to do the little surface grinding that I have to do. riceone

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                      • #12
                        The drill press grinder idea may not be quite as bad if the words "cheap import drill press" are replaced with something more expensive.

                        In case someone does not know, the cheap ones often (not always) have ONE bearing down by the chuck. The other end of the skinny spindle is just trapped in a sloppy spline driver at the top of the head.

                        That dude will walk the stone right up on the part as the skinny spindle deflects and moves in the splines, and then sling the work somewhere when it gets in a bind. or maybe it'll just break the stone and sling the whole works.

                        If it won't work as a cheap mill, it sure as heck won't work as a cheapo Blanchard grinder.

                        I still wouldn't LIKE it, but it wouldn't be quite as much of a guaranteed problem with a more solid press.

                        Almost as bad as the trimmers at a vacuum-forming plant I visited..... drill presses with circular saw blades chucked up, and some minimal guarding. Couldn't guard them really well, the work had to slide in to get the top trimmed off.

                        Note to self, do NOT lift hand UP!
                        1601

                        Keep eye on ball.
                        Hashim Khan

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                        • #13
                          Originally posted by Evan
                          I don't have any experience using a swing grinder but they are common as low wages in the foundry business. They use ones that are suspended from chains, arms, booms or stands and use them to grind off flash etc. John S sent me this picture and I think with proper care and some guarding to prevent the work shifting toward the operator it would be reasonably safe. I sure don't like the idea of using a radial arm saw. I have a 10" Sears made about 30 years ago and that tool scares me almost as much as a chainsaw, maybe more.
                          If your 10 inch Sears saw scares you enough that you don't want to use it anyway, check out this site:

                          http://www.radialarmsawrecall.com/faq.asp

                          I like radial arm saws myself, and regularly use one of the recalled ones, but if a better guard will help, you might as well get one, or if it's too old and is going to be consigned to scrap anyway, you might as well get something for it if you can.

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                          • #14
                            Anyone built one using these plans? http://www.dm.net/~lughaid/vest.htm

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                            • #15
                              Guy Lutard has a bit about making a simple "spot grinder" using a cheap granite surface plate. You take it to a counter top shop and have them bore a hole for a vertical column and then make a work head. The work is just slid back and forth under the launcher...uh...er workhead by hand The key is that its used for spot grinding by grinding the highest spot first and then *very slowly* working downward until the piece is flat...maybe taking a few tenths at a time.

                              As for using a milling machine....I would say forget it unless you are trying to destroy it. You will end up with the equivalent of clover lapping compound on the ways as bits of silicon carbide mix with oil and get trapped between the way surfaces.

                              Real surface grinders have totally covered way surfaces. That is, no portion of the oily way surfaces are exposed when you run the table back and forth.

                              Paul
                              Paul Carpenter
                              Mapleton, IL

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