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  • You mill drill guys....

    I've been asked many times to show the 3" post I cemented into the column on this mill...and to show the jacking bolt setup I use to aid in tramming this thing. The bolts also add stability to the lower base. Without them the base can actually flex. This whole affair ties it all together. It's ugly.. I did it in a hurry and grabbed whatever fit at the time. The big bolt in the bottom of the shaft goes right through and jacks against the base toward the front. You can figure the rest out I guess. Some of the stuff is welded on afterwards...way inside. More bracing to steady things.
    Add this to the "Million Ways to Improve A Mill Drill" deal that everyone hates

    Russ
    I have tools I don't even know I own...

  • #2
    Good stuff torker!

    I am engaged in filling my mill's base and column with epoxy granite to dampen vibration and increase its dynamic strength. At least that's my story, and I'm sticking to it!

    The fill material is a mixture of granite gravel, sand, and epoxy. It molds real nicely:



    Filling the base was very straightforward:





    What you see there is all dry and solid as a rock. It increased the weight of the base from about 100 lbs to nearly 200 lbs. I will be partially filling the column as well as increasing the strength of the connection between column and base with a monster big bolt to add to the existing bolts.

    The nice thing about the epoxy is it bonds well to the cast iron, it adds no moisture so does not promote corrosion, and it is pretty neutral in terms of changing size as it sets up.

    I like your jacking screw arrangement for tramming your column.

    Lastly, I am adding a one shot oiling system I'm fabricating.

    You can do quite a lot to improve these machines.

    Best,

    BW
    ---------------------------------------------------

    http://www.cnccookbook.com/index.htm
    Try G-Wizard Machinist's Calculator for free:
    http://www.cnccookbook.com/CCGWizard.html

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    • #3
      That's an interesting idea. It had been suggested to me many years ago to fill the column of my JET mill-drill with concrete, to help stiffen it and damp vibration, but as noted, I was concerned with moisture and corrosion.

      The column of my mill is cast iron, thinner walled that I'd have expected (especially given the weight of the head) and extremely rough inside.

      I eventually made a heavy table with supports on either side of the regular column, and that did help some, but I have been gathering ideas to optimize it more so it's more useful.

      Is this epoxy granite a commercial item, or does one just mix fancy fishtank gravel with some JB weld and call it good.

      Doc.
      Doc's Machine. (Probably not what you expect.)

      Comment


      • #4
        Here's a photo of the stand:



        It's all heavywall pipe and plate, fully welded. The perforated legs are "gun casing"- oil well casing that's dropped down the well full of a seies of small shaped explosive charges. The charges perforate the casing, crack the rock, and allow greater oil production.

        But I digress.

        I put a lot of miles on this poor mill before I picked up the Bridgy clone- you can see the "shadow" on the wall, notably behind the leftmost upright just above the table, of the "spray" from cutting oils, chips and other swarf.

        The one thing I didn't do, though, is build in any option to tram the mill- I'd assumed that the fixed column couldn't be trammed, so I fitted the upper bracket as closely as I could and called it good.

        Doc.
        Doc's Machine. (Probably not what you expect.)

        Comment


        • #5
          Originally posted by Doc Nickel
          That's an interesting idea.
          Is this epoxy granite a commercial item, or does one just mix fancy fishtank gravel with some JB weld and call it good.

          Doc.

          You can read all about it on his website/blog

          http://www.cnccookbook.com/CCMillEpoxyFill.htm

          Comment


          • #6
            Very cool, and some tips for working with epoxy that I'd never come across elsewhere - like using a little torch for popping bubbles.

            One point - I've had epoxy "cook off" on me - get hot enough to smoke, when it was in large volumes. Could that be a problem in the column? Or is the volume of epoxy low enough that it doesn't really get very hot?

            WEST makes a "high-temperature" hardener for use in the Summer (that is, it's slower than the regular hardener), and that would slow the reaction down.

            Thanks for a very good, and easily-followed, description.
            Pete in NJ

            Comment


            • #7
              I've had epoxy "kick" and get real hot too, but have not seen that for this project. It could be the West epoxy I'm using, or it could be that I mix it up in relatively small batches added one after the other, but I have hardly felt it getting warm to the touch, let alone hot.

              FWIW, there is a cheaper epoxy supplier than West Marine that is mentioned on the original CNCZone E/G thread. I don't have the link handy, but you can find it. My West epoxy cost about the same because I got some "scratch and dent".

              As to how precise it all has to be. There are thousands of posts over on CNCZone about minute details. Those guys were ordering precision aggregates in 5 sizes, "Zeospheres", wetting compounds, deairing compounds, lamp black, you name it. It's not clear to me that they were getting dramatically better results from all that, and I wanted to get on with a project using locally available materials.

              Filling existing castings is a much less demanding task than casting up entire machines from this stuff, which is what the CNCZone guys were after. I think this simplified approach will work very well for filling castings. Since I am lucky enough to have 2 identical mills, I intend to try to cook up some tests of some kind to quantify how much this has helped. Any ideas would be appreciated.

              Meanwhile, DocNickel, I like your column brace and as mentioned I really like Torker's jacking arrangement too.

              One thought if you were to fill a column entirely. You may want some kind of vibrating arrangement to help the air out of the mixture inside the column. Some of the CNCZone guys were using concrete vibrators from Harbor Freight for the purpose.

              Cheers,

              BW
              ---------------------------------------------------

              http://www.cnccookbook.com/index.htm
              Try G-Wizard Machinist's Calculator for free:
              http://www.cnccookbook.com/CCGWizard.html

              Comment


              • #8
                Originally posted by kben77
                You can read all about it on his website/blog

                http://www.cnccookbook.com/CCMillEpoxyFill.htm
                I'm surprised that Bob's Blog never mentions that a great deal of the hard work on the CNCzone epoxy granite thread, including the optimal aggregate forumula that Bob quotes, the sources for the aggregates and the West Epoxy, came from Cameron ("ckelloug") -- an active member here.

                Cameron's "optimal" formula, which Bob quotes on his blog, was derived by some heavy-duty mathematical analysis of the de Larrard Packing Models and then computer simulation of the classic 3D packing problem: how to fill the greatest percentage of the 3D volume with the smallest spacing between the aggregate components.

                The reason the packing density is important (and the reason the commerical epoxy granite mixtures are trade secrets) is that the tighter you pack the aggregate, the higher the dynamic strength of the resulting pour.

                Cameron's optimal mix achieves someone on the order of 93% packing, which is amazing:

                20% Agsco #6 Aluminum Oxide
                20% Agsco #4 Quartz
                20% Agsco #2 Quartz
                20% Agsco #2/0 Quartz
                20% 3M #800 Zeeospheres

                ...and here's what Cameron's formula looks like when you pour it. That entire block is epoxy granite:

                http://www.cnczone.com/forums/attach...1&d=1186248447


                Cameron wrote a paper on the analysis and derivation of the formula here:

                http://www.cnczone.com/forums/attach...9&d=1203602933

                He posted a general synopsis of the problem and his solution here:

                http://www.cnczone.com/forums/showpo...postcount=1824

                Great job Cameron!!!
                Last edited by lazlo; 03-21-2008, 01:51 PM.
                "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

                Comment


                • #9
                  why not just fill it with lead?, prolly cheaper.
                  "four to tow, two to go"

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                  • #10
                    Lead would work exceptionally well to damp vibration Speedsport, but it wouldn't do anything to improve the dynamic stiffness.
                    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                    • #11
                      lazlo, you never heard of "having lead in your pencil" & dynamic stiffness?
                      "four to tow, two to go"

                      Comment


                      • #12
                        Thanks for the info Russ, I know you work the bajeezus out of that mill/drill, so if it's working for you it has definitely passed the acid test.
                        I'll want give that a try as soon as I unpaint my way out of the corner I'm in now.

                        I'm not sure what you used for a concrete mix but I do remember that you used a rod mounted on a air chisel as a vibrator for help in removing entrained air and improving density. Correct me if I'm wrong.

                        I'm also curious if anybody has ever used a product such as Blok Hard .

                        For those not familiar with this product, it is a product commonly added to the water jacket area in high horsepower drag race engines in order to increase block stiffness and cylinder integrity. I've seen it work magic in engines not originally not designed for such high power levels. Just thought that this application would be a natural for such a product. Not cheap though, as i think it works out to about $70-$80 for twenty eight lbs.
                        Home, down in the valley behind the Red Angus
                        Bad Decisions Make Good Stories​

                        Location: British Columbia

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                        • #13
                          Thanks for the kudos, Lazlo. There are lots of folks that deserve credit for the success of the E/G thread on CNCZONE! They're all over the world including Canada, England, and France.

                          The supplier of cheap epoxy that Bob mentions is www.uscomposites.com

                          The photo of the cnc router gantry top quoted in Lazlo's post is by Walter Jarog in Chicago posted on CNCZone. Walter was the original instigator of the Epoxy/granite thread. I just happened to be interested and worked on it further providing walter some formulating suggestions.

                          In general, if the machine that you are trying to fill is already structurally sound, the E/G mixture used to fill it won't really matter: you're basically just adding mass and mass that has high damping at that. The point of optimizing an E/G formula is for building all composite machines.

                          Lead in epoxy would also be a good damping addition although it has very low strength. It must be remembered that with epoxy granite, a lot of the vibration damping is from the fact that E/G is like a giant bucket of masses, springs and dampers rather than something with uniform properties like metal.

                          According to the rule of mixtures and the Hashin-Shtrikman Bounds, the stiffness and ultimate strength of the material can be extremely sensitive to the proportions of the stronger and weaker components. The sensitivity and the gain to be had by a tiny improvement in density are largest once you get over about 90% aggregate. With aggregate densities of 50% and 80% it may hardly make a difference. Between 80% and 95% aggregate there is the potential for a doubling of the modulus.

                          The torch for popping bubbles is good for cosmetic surface bubbles but less effective at the internal bubbles that lower the density of the material overall. The torch was suggested by lgalla on CNCZone many times. In that air bubbles only occur in the epoxy phase, the less epoxy you use, the fewer the bubbles is the attitude I've been taking.

                          At any rate, after a year of modeling and advising the adventurous, I am just about to start running modulus and strength tests on my admet materials test machine. Those results will get posted to the epoxy granite thread on CNCZone when I get done.

                          Finally, it should be noted that Walter added an entry for Epoxy/Granite to the wikipedia which is a good short read http://en.wikipedia.org/wiki/Epoxy-granite

                          I'm glad to see the interest here and happy to see credit go to all those deserving souls on CNCZONE who have done the hard work (including lazlo, myself, and BobWarfield whom I know are on both boards).

                          Cheers all,

                          Cameron

                          Comment


                          • #14
                            Originally posted by Willy
                            I'm also curious if anybody has ever used a product such as Blok Hard.
                            Blok Hard came up in one of the discussions on the Yahoo Mill/Drill group about filling the column with concrete. But it just looks like iron-filled hydraulic cement?

                            At $2.75/lb for block hard, you may as well go for DuraBar or VersaBar, which is $1.70/lb (but not pourable, obviously)
                            Last edited by lazlo; 03-21-2008, 04:29 PM.
                            "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                            • #15
                              Lazlo I'm sure Torker will fill in the gaps here but I think he used the steel shaft encased in concrete. That is why I mentioned the air chisel vibrator.

                              If I remember correctly he used rags to plug the bottom of his column and had the shaft project out of the bottom.
                              Home, down in the valley behind the Red Angus
                              Bad Decisions Make Good Stories​

                              Location: British Columbia

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