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Re: Modding for more rigidity on an M3?

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  • mikauvalley
    Hello mike @ the lost brain :Wood can and will probably warp, due to gaining or loosing moisture. If you use lag bolts, you might create localized
    Message 1 of 16 , Jul 6 10:19 AM
      Hello "mike @ the lost brain":
      Wood can and will probably warp, due to gaining or loosing moisture.  If you use lag bolts, you might create localized depressions or warps in the baseplate.
      For concrete, you can buy  small 60 lb ready mix bags at Lowes or Home Depot.  These have a 1/2" +- gravel agggregate.  Make a mold rigid enought to not warp with the weight of the concrete.  (Screw all wood connections so that you can later unscrew and remove the mold parts without damaging the concrete).  When placing the concrete, have it medium wet, not soup, and vibrate the mold to make the concrete fill all voids.  Remember that the mold will be upside down, so the finished top concrete base will be at the bottom of the mold.  Just screed the top of the mold (which will be the bottom of the concrete base) with a smooth straight edge board.  The bottom of mold (to be top of concrete base) does not need to be completely smooth because tile adjesive or liguid nail will provide about a 1/16"-1/8" cushion between concrete and micRo base plate.  Adhesives will grip the base plate throughout, no localized depression - - but, once glued down, you may not be able to remove it, so if you go this way, get it right the first time.
      :)
      Mikau

      --- In micRo-cnc@yahoogroups.com, "mkrzenski@..." <mike@...> wrote:
      >
      > I've actually thought of the concrete idea as well. :) (actually thought of making a whole rigid machine out of it lol) It's really not a bad idea either but wonder though what mix would create a nice smooth consistency as my only experience with concrete was for doing fence posts and that was some pretty rough / chunky stuff.
      > Another thought that I never really even considered is I could just lag the damn thing down to the workbench it's on. The bench top is 3/4 birch ply and is sturdy as heck. Would probably need another piece of ply directly under the base prior to the bench surface with cutouts at the corners to create clearance for the screws that hold the blocks to the base.
      > If the base were lagged down in that fashion via a couple of countersunk holes I'd imagine that would offer a pretty good improvement! :)
      > Thoughts?

    • Dan Andersson
      Here comes my 5 Cents worth of comments and opinions on the subject. Concrete base? Yes, it works fine. It s easy to make the base absolutely flat and you can
      Message 2 of 16 , Jul 6 2:37 PM
        Here comes my 5 Cents worth of comments and opinions on the subject.


        Concrete base?

        Yes, it works fine. It's easy to make the base absolutely flat and you can allow the alu base ( if still used ) to rest on the concrete base.

        However, retaining the alu base is retaining very much of the problem.

        First,you need a water proof concrete to avoid conamination, absorbtion and leakage of oil and cooling fluid.

        Secondly, you need to mount the X way corner posts in the concrete base and get rid of the alu base. The alu base is the reason to the rigidy problem.

        The same goes for the granite slab base.

        I have a granite slab on order. The first delivery was wrongly cut and drilled by the supplier... Dooh! It have to wait until January now.

        The M2 is mostly good enough, it's the M3 that is wobbly. This is also a source to systematic runout.

        If you tighten up the anti backlash measures, the base surface changes - it's popping upwards a significant amount of mm's.

        Spindles etc.

        The Foredom and Wecheer are both not to bad. The flexshaft concept is maybe not ideal but it works. However, the cheaper Chinese motor+flexshaft is dodgy as it's currently not possible to find replacement carbons!

        When my motor dies, I'll go for the extra rigid flex shaft and motor unless I managed to make good BLDC solution and the Foredomor an ER11 collet axis spindle..

        Also, the Wecheer only comes with 3 diffeent collets in imperials. I had to turn a set of Wecheer collets in the lathe so I have a complete set of metric and imperial sizes.
        It is IMPORTANT to have the right collet. Wrong collet .eq. high runout.
        The M3 is not rigid enough for ER16 collets and upwards. 6mm or 1/4" is probably what I can recommen as max diameter for the bits.

        BLDC motors are a good idea. Just choose a low rpm motor <800 as you need the torque. Air driven spindles are nice but rather uselesss on low rpms. You can't always mill at 50k-200 k RPM! And they mostly limit the bit size to 1/8" or 3.x mm. But on low speed, the torque sux!
        As written before, try running and loading the BLDC as low as possible. They are not built for a 24 hours milling job! And th #$%^&*@ ballbearings!!! Get SKF stuff or the American made equivalents!

        Te watercooled inborders are mostly to heavy as well as 80mm diameter. The foredom spindle is only 1" diameter!

        The micRO doesn't do metal low speed milling well. You need to go high speed. Chose tools accordingly. Chose coated bits intended for dry runs. The micRO can mill Titanium ths way.

        Using the heavier Dremels and standard routers with the micRO is not a good idea.

        For precision work in hard metal etc, always cut in+/- Y direction as this is the most rigid movement.

        I'm off on a new contract job from Monday and onwards, so I'm out of my garage until January. If I get a years extention from the client, I'll move my electronics and CNC lab to Sweden, Karlskrona to prevent me going mad because of utter bore...



        //Dan, M0DFI

        On Fri, 06 Jul 2012 17:19:29 -0000
        "mikauvalley" <rein.vall@...> wrote:

        > Hello "mike @ the lost brain":Wood can and will probably warp, due to
        > gaining or loosing moisture. If you use lag bolts, you might create
        > localized depressions or warps in the baseplate.For concrete, you can
        > buy small 60 lb ready mix bags at Lowes or Home Depot. These have a
        > 1/2" +- gravel agggregate. Make a mold rigid enought to not warp with
        > the weight of the concrete. (Screw all wood connections so that you can
        > later unscrew and remove the mold parts without damaging the concrete).
        > When placing the concrete, have it medium wet, not soup, and vibrate the
        > mold to make the concrete fill all voids. Remember that the mold will
        > be upside down, so the finished top concrete base will be at the bottom
        > of the mold. Just screed the top of the mold (which will be the bottom
        > of the concrete base) with a smooth straight edge board. The bottom of
        > mold (to be top of concrete base) does not need to be completely smooth
        > because tile adjesive or liguid nail will provide about a 1/16"-1/8"
        > cushion between concrete and micRo base plate. Adhesives will grip the
        > base plate throughout, no localized depression - - but, once glued down,
        > you may not be able to remove it, so if you go this way, get it right
        > the first time. [:)] Mikau
        > --- In micRo-cnc@yahoogroups.com, "mkrzenski@..." <mike@...> wrote:
        > >
        > > I've actually thought of the concrete idea as well. :) (actually
        > thought of making a whole rigid machine out of it lol) It's really not a
        > bad idea either but wonder though what mix would create a nice smooth
        > consistency as my only experience with concrete was for doing fence
        > posts and that was some pretty rough / chunky stuff.
        > > Another thought that I never really even considered is I could just
        > lag the damn thing down to the workbench it's on. The bench top is 3/4
        > birch ply and is sturdy as heck. Would probably need another piece of
        > ply directly under the base prior to the bench surface with cutouts at
        > the corners to create clearance for the screws that hold the blocks to
        > the base.
        > > If the base were lagged down in that fashion via a couple of
        > countersunk holes I'd imagine that would offer a pretty good
        > improvement! :)
        > > Thoughts?
        >
        >
      • Dan Andersson
        With low RPM
        Message 3 of 16 , Jul 6 2:42 PM
          With low RPM <800 I mean a low K value below 800. A K800 and 12V is a 12*800 RPM motor. 10K RPM is not to bad with a good torque.

          //Dan

          On Fri, 6 Jul 2012 22:37:23 +0100
          Dan Andersson <dan@...> wrote:

          >
          >
          > Here comes my 5 Cents worth of comments and opinions on the subject.
          >
          >
          > Concrete base?
          >
          > Yes, it works fine. It's easy to make the base absolutely flat and you can allow the alu base ( if still used ) to rest on the concrete base.
          >
          > However, retaining the alu base is retaining very much of the problem.
          >
          > First,you need a water proof concrete to avoid conamination, absorbtion and leakage of oil and cooling fluid.
          >
          > Secondly, you need to mount the X way corner posts in the concrete base and get rid of the alu base. The alu base is the reason to the rigidy problem.
          >
          > The same goes for the granite slab base.
          >
          > I have a granite slab on order. The first delivery was wrongly cut and drilled by the supplier... Dooh! It have to wait until January now.
          >
          > The M2 is mostly good enough, it's the M3 that is wobbly. This is also a source to systematic runout.
          >
          > If you tighten up the anti backlash measures, the base surface changes - it's popping upwards a significant amount of mm's.
          >
          > Spindles etc.
          >
          > The Foredom and Wecheer are both not to bad. The flexshaft concept is maybe not ideal but it works. However, the cheaper Chinese motor+flexshaft is dodgy as it's currently not possible to find replacement carbons!
          >
          > When my motor dies, I'll go for the extra rigid flex shaft and motor unless I managed to make good BLDC solution and the Foredomor an ER11 collet axis spindle..
          >
          > Also, the Wecheer only comes with 3 diffeent collets in imperials. I had to turn a set of Wecheer collets in the lathe so I have a complete set of metric and imperial sizes.
          > It is IMPORTANT to have the right collet. Wrong collet .eq. high runout.
          > The M3 is not rigid enough for ER16 collets and upwards. 6mm or 1/4" is probably what I can recommen as max diameter for the bits.
          >
          > BLDC motors are a good idea. Just choose a low rpm motor <800 as you need the torque. Air driven spindles are nice but rather uselesss on low rpms. You can't always mill at 50k-200 k RPM! And they mostly limit the bit size to 1/8" or 3.x mm. But on low speed, the torque sux!
          > As written before, try running and loading the BLDC as low as possible. They are not built for a 24 hours milling job! And th #$%^&*@ ballbearings!!! Get SKF stuff or the American made equivalents!
          >
          > Te watercooled inborders are mostly to heavy as well as 80mm diameter. The foredom spindle is only 1" diameter!
          >
          > The micRO doesn't do metal low speed milling well. You need to go high speed. Chose tools accordingly. Chose coated bits intended for dry runs. The micRO can mill Titanium ths way.
          >
          > Using the heavier Dremels and standard routers with the micRO is not a good idea.
          >
          > For precision work in hard metal etc, always cut in+/- Y direction as this is the most rigid movement.
          >
          > I'm off on a new contract job from Monday and onwards, so I'm out of my garage until January. If I get a years extention from the client, I'll move my electronics and CNC lab to Sweden, Karlskrona to prevent me going mad because of utter bore...
          >
          >
          >
          > //Dan, M0DFI
          >
          > On Fri, 06 Jul 2012 17:19:29 -0000
          > "mikauvalley" <rein.vall@...> wrote:
          >
          > > Hello "mike @ the lost brain":Wood can and will probably warp, due to
          > > gaining or loosing moisture. If you use lag bolts, you might create
          > > localized depressions or warps in the baseplate.For concrete, you can
          > > buy small 60 lb ready mix bags at Lowes or Home Depot. These have a
          > > 1/2" +- gravel agggregate. Make a mold rigid enought to not warp with
          > > the weight of the concrete. (Screw all wood connections so that you can
          > > later unscrew and remove the mold parts without damaging the concrete).
          > > When placing the concrete, have it medium wet, not soup, and vibrate the
          > > mold to make the concrete fill all voids. Remember that the mold will
          > > be upside down, so the finished top concrete base will be at the bottom
          > > of the mold. Just screed the top of the mold (which will be the bottom
          > > of the concrete base) with a smooth straight edge board. The bottom of
          > > mold (to be top of concrete base) does not need to be completely smooth
          > > because tile adjesive or liguid nail will provide about a 1/16"-1/8"
          > > cushion between concrete and micRo base plate. Adhesives will grip the
          > > base plate throughout, no localized depression - - but, once glued down,
          > > you may not be able to remove it, so if you go this way, get it right
          > > the first time. [:)] Mikau
          > > --- In micRo-cnc@yahoogroups.com, "mkrzenski@..." <mike@...> wrote:
          > > >
          > > > I've actually thought of the concrete idea as well. :) (actually
          > > thought of making a whole rigid machine out of it lol) It's really not a
          > > bad idea either but wonder though what mix would create a nice smooth
          > > consistency as my only experience with concrete was for doing fence
          > > posts and that was some pretty rough / chunky stuff.
          > > > Another thought that I never really even considered is I could just
          > > lag the damn thing down to the workbench it's on. The bench top is 3/4
          > > birch ply and is sturdy as heck. Would probably need another piece of
          > > ply directly under the base prior to the bench surface with cutouts at
          > > the corners to create clearance for the screws that hold the blocks to
          > > the base.
          > > > If the base were lagged down in that fashion via a couple of
          > > countersunk holes I'd imagine that would offer a pretty good
          > > improvement! :)
          > > > Thoughts?
          > >
          > >
        • mikauvalley
          My 6 cents worth. ... can allow the alu base ( if still used ) to rest on the concrete base.To make a concrete base absolutely flat for cnc accuracy, it would
          Message 4 of 16 , Jul 6 3:40 PM
            My 6 cents worth.
            --- In micRo-cnc@yahoogroups.com, Dan Andersson <dan@...> wrote
            > Concrete base?
            > Yes, it works fine. It's easy to make the base absolutely flat and you can allow the alu base ( if still used ) to rest on the concrete base.
            To make a concrete base absolutely flat for cnc accuracy, it would have to be polished with a precise machine.  Very difficult.
            > However, retaining the alu base is retaining very much of the problem.  By using an soft adhesive that allows setting the base plate like a tile, the aluminum base will not deflect once the adhesive sets, but you will have to live with any pre-existing plate warps.
            > First,you need a water proof concrete to avoid conamination, absorbtion and leakage of oil and cooling fluid.  It really does not matter if the concrete gets stained for this application.  The soft adhesive between the concrete and the aluminum plate will create dielectric isolation to keep the aluminum base from corroding by avoiding direct contact to the concrete.  (This is why aluminum flashings embedded in masonry walls are coated with asphalt).  Sealing the concrete with a concrete sealer would help in minimizing aluminum corrosion assuming oil or cooling fluid that get on concrete gets back up on aluminum base plate, via a coolant pump system, assuming you are cutting metals.
            > Secondly, you need to mount the X way corner posts in the concrete base and get rid of the alu base. The alu base is the reason to the rigidy problem.
            It is really difficult to set the corner posts absolutely level and at exact locations at all corners of concrete unless you have another gantry mill to do that.   Keeping the base is the easier option.
            Mikau.

          • ipeerbhai@ymail.com
            Ok, I m coming in late to an old topic. Where is the flex coming from -- anyone figure it out? Is it the base? If it s the base -- why not re-enforce on the
            Message 5 of 16 , Sep 27, 2012
              Ok, I'm coming in late to an old topic.
              Where is the flex coming from -- anyone figure it out? Is it the base?

              If it's the base -- why not re-enforce on the under side with 80/20 or something bolted down in strategic locations? For example, around the edges or something?

              You could even attach ren-forcement strips ( kind of like turning the base into a giant T beam )?

              Also -- The micRo is nice because of appearance. I don't know enough about it -- is it actually a good mill? What are its limits, and why?


              --- In micRo-cnc@yahoogroups.com, "mikauvalley" <rein.vall@...> wrote:
              >
              > My 6 cents worth.
              > --- In micRo-cnc@yahoogroups.com, Dan Andersson <dan@> wrote
              > > Concrete base?
              > > Yes, it works fine. It's easy to make the base absolutely flat and you
              > can allow the alu base ( if still used ) to rest on the concrete base.To
              > make a concrete base absolutely flat for cnc accuracy, it would have to
              > be polished with a precise machine. Very difficult.
              > > However, retaining the alu base is retaining very much of the problem.
              > By using an soft adhesive that allows setting the base plate like a
              > tile, the aluminum base will not deflect once the adhesive sets, but you
              > will have to live with any pre-existing plate warps.
              > > First,you need a water proof concrete to avoid conamination,
              > absorbtion and leakage of oil and cooling fluid. It really does not
              > matter if the concrete gets stained for this application. The soft
              > adhesive between the concrete and the aluminum plate will create
              > dielectric isolation to keep the aluminum base from corroding by
              > avoiding direct contact to the concrete. (This is why aluminum
              > flashings embedded in masonry walls are coated with asphalt). Sealing
              > the concrete with a concrete sealer would help in minimizing aluminum
              > corrosion assuming oil or cooling fluid that get on concrete gets back
              > up on aluminum base plate, via a coolant pump system, assuming you are
              > cutting metals.
              > > Secondly, you need to mount the X way corner posts in the concrete
              > base and get rid of the alu base. The alu base is the reason to the
              > rigidy problem.It is really difficult to set the corner posts absolutely
              > level and at exact locations at all corners of concrete unless you have
              > another gantry mill to do that. Keeping the base is the easier option.
              > Mikau.
              >
            • m0dfi
              Flex, where is the flex coming from? At low XY forces, the base. At high XY forces, the base and the two gantry blocks. At low and high Z forces, the base and
              Message 6 of 16 , Oct 6, 2012
                Flex, where is the flex coming from?

                At low XY forces, the base.

                At high XY forces, the base and the two gantry blocks.

                At low and high Z forces, the base and the Zblock mount. You get lower flex and better accuracy at the XY corners due to less base flex.

                A good mill? Yes, one of the very best small mills due to lumenlabs spending on MacMaster quality stuff - one of the reasons the went bust. The micRO was to expensive to build at the price the sold it for.

                A good mill? Yes, in my opinion, one of the best below 5000$.

                If we can sort out the base flex once and for all, it is abrilliant cnc, especially the smaller M2.


                //Dan

                --- In micRo-cnc@yahoogroups.com, "ipeerbhai@..." <ipeerbhai@...> wrote:
                >
                > Ok, I'm coming in late to an old topic.
                > Where is the flex coming from -- anyone figure it out? Is it the base?
                >
                > If it's the base -- why not re-enforce on the under side with 80/20 or something bolted down in strategic locations? For example, around the edges or something?
                >
                > You could even attach ren-forcement strips ( kind of like turning the base into a giant T beam )?
                >
                > Also -- The micRo is nice because of appearance. I don't know enough about it -- is it actually a good mill? What are its limits, and why?
                >
                >
                > --- In micRo-cnc@yahoogroups.com, "mikauvalley" <rein.vall@> wrote:
                > >
                > > My 6 cents worth.
                > > --- In micRo-cnc@yahoogroups.com, Dan Andersson <dan@> wrote
                > > > Concrete base?
                > > > Yes, it works fine. It's easy to make the base absolutely flat and you
                > > can allow the alu base ( if still used ) to rest on the concrete base.To
                > > make a concrete base absolutely flat for cnc accuracy, it would have to
                > > be polished with a precise machine. Very difficult.
                > > > However, retaining the alu base is retaining very much of the problem.
                > > By using an soft adhesive that allows setting the base plate like a
                > > tile, the aluminum base will not deflect once the adhesive sets, but you
                > > will have to live with any pre-existing plate warps.
                > > > First,you need a water proof concrete to avoid conamination,
                > > absorbtion and leakage of oil and cooling fluid. It really does not
                > > matter if the concrete gets stained for this application. The soft
                > > adhesive between the concrete and the aluminum plate will create
                > > dielectric isolation to keep the aluminum base from corroding by
                > > avoiding direct contact to the concrete. (This is why aluminum
                > > flashings embedded in masonry walls are coated with asphalt). Sealing
                > > the concrete with a concrete sealer would help in minimizing aluminum
                > > corrosion assuming oil or cooling fluid that get on concrete gets back
                > > up on aluminum base plate, via a coolant pump system, assuming you are
                > > cutting metals.
                > > > Secondly, you need to mount the X way corner posts in the concrete
                > > base and get rid of the alu base. The alu base is the reason to the
                > > rigidy problem.It is really difficult to set the corner posts absolutely
                > > level and at exact locations at all corners of concrete unless you have
                > > another gantry mill to do that. Keeping the base is the easier option.
                > > Mikau.
                > >
                >
              • mikauvalley
                Hi Folks:Flex comes from everthing: the thin base, the guide rails, the plastic blocks, how the spindle (a) is mounted, the material being milled (b), the
                Message 7 of 16 , Oct 15, 2012
                  Hi Folks:
                  Flex comes from everthing: the thin base, the guide rails, the  plastic blocks, how the spindle (a) is mounted, the material being milled (b), the sacrificial piece, the clamping of the stock (c), the feed rate (d) of milling, the length/thickness/sharpness (e) of the end mill, and others, I'm sure.
                    a.  I have seen some pictures of user's micro's with the spindle gripped at the top.  Gripping it at the bottom would make it more rigid.
                    b.  Some materials will flex more than others during milling.  Also, some materials, if not properly annealed, will warp during milling, such as in metals.  Even plastics will warp at thinned-out areas.
                    c.  Location of stock clamps can affect flexing of stock and base.
                    d.  Innapropriate feed rates (speed, bite) will flex stock, base, blocks, end mills.
                    e.  Long, thin end mill will flex when feed rate is too high and deep for tool being used and material being cut; a dull tip will not help.

                  So the best defense against flex is knowledge of how to incorporate all the parameters optimally for the strength and limitations of the MicRo.  If you want super accurate conditions, mortgage your home and buy a mill that has parts as thick as a dinosaur's neck.  Other than that, the micRo is a great little machine for the price.

                  Mikau

                  --- In micRo-cnc@yahoogroups.com, "m0dfi" <dan@...> wrote:
                  >
                  > Flex, where is the flex coming from? 
                  > A good mill? Yes, in my opinion, one of the best below 5000$.

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