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  1. #11

    some points:

    1. Spindle:

    -How did you get to the conclusion that you need ER32 collet? You say ice is soft and easy to route. 2.2KW SPINDLE WILL LOWER THE COST OF THE BUILD CONSIDERABLY. Furthermore there are on the market many Carbide bits that have the cutting area much bigger than the shank. these will be perfect for rough 3d jobs with rapid removal

    -Water cooled is a must, just run normal antifreeze.

    -Bearing grease will not be a problem. -5C is not a big deal. Just run the spindle slower to faster some minutes every time, so it can heat a bit. You will need to do also the following things: make additional bracket and fit a seal on the spindle shaft, best would be if you change the grease with salt water resistant grease/ Mitchel, etc./ , the one they use in fishing. it is a very fast grease, so no worries there. For sure its better than the original one :-)

    2. Frame

    it should be at least bi component industrial coating marine epoxy painted or you would be sorry very soon. Best would be inox and then epoxy painted. Yeah, inox rusts too

    3. Rails must be inox, Hiwin has inox rails and carriages.

    I see your biggest problem with "chip and dust removal and damage" , cause your chips would be water. hence water will go all the time where it should not. Ok, electrical connections could be dipped in polyurethane/ via hot melt gun and polyurethane glue bars/ but never the less all steppers have shafts, so those shafts have to have additional seals.

    I see it working if you plan use it in a room where is -5C. I see that you looked at the machine i am making. Following a similar design is easy to protect all ball screws.

    But if you plan only an enclosure where is -5C, i see it very difficult-aluminum also f***s in moisture , so more or less every metal part left visible-shafts, plates, bolts, ball screw supports, ball screw nuts etc., should be sealed or painted over. Same goes with the cables, their ends and connections must be dipped in polyurethane.

  2. Rather than seal spindle shaft, replace lower spindle bearing with a food grade sealed stainless steel one, lasts forever in adverse conditions.

  3. #13

    Silyavski thanks for your input although it seems to me that you might have missed my first post or miss read it. As I explained there my starting point in this cnc machine is an end Mill with the measurements of 250 mm long excluding the shaft and 23 mm in diameter. The shaft is 19.5 mm in diameter so I guess that explains where the Er32 collet comes from. Also due to the length of the end mill the 5 hp spindle is definitely needed. I know this from experience working with ice cnc machines before. We have used a perske 5.5 hp air cooled spindle without any special sealing and 5 years on is still going strong with at least 6 hours run time per day.
    Although I might look into special sealing I don't find it necessary as explained earlier there is no water involved at all as the machine and material is constantly at - 5 degrees so all the chips are powder snow... And a lot of it.
    Also carbide bits don't work on ice in fact only special bits made for ice work. I have tried all sorts of bits before just to see as ice bits are quite expensive but no luck... hence the price. For instance that 250 mm bit costs 350 dollars and by the time I get it to the UK cost just as much in pounds sterling.
    I do appreciate your input and time and hopefully you understand better now what I am up against.
    Also the machine won't be in a cell, it will be in a very large freezer in fact my ice studio so even while loading and unloading will stay at that temperature.
    My difficulty at the moment is the very large z travel as my material is also 250 mm high and with the bit lifted above it the spindle needs to travel to other areas but would need to work on thinner slabs of ice as well with smaller bits.
    Anyway I did not have any free time in the past few weeks to think about it but hopefully will be able to upload some drawings by the end of the week to discuss it further.
    Thanks again for the comments.

  4. #14
    Hello again,

    I have been quite busy lately with work, but I think I finally know which way I am going with this build and some help would be appreciated.

    So far I have the structure and now comes the part where I have to decide what size stepper motors to use and what diameter should my lead screws be as I would like to design the mounts for them.

    I assume the stepper motor or servo choice defines the control board choice as well.

    A couple of questions:

    Can the gantry weight be guestimated ? Yes I am quite lazy to find out the weight of each component :) I know that the spindle motor is 15 kg :)

    If yes than what size and torque motors would suite my design? ( I would like it to be fast and strong. Strong enough for wood in comparison )

    I assume belt drive is not the best choice in a sub zero environment therefore I have the option of direct drive or Chain and sprocket. What would be the best choice?

    I would like to use Mach 3 as the controller and would like to upgrade to 4 axes as soon as I am done with the build. Do you have any suggestions on control boards and the electronics involved?

    Here are a couple of pictures of the structure to make things a bit clearer:

    Light Grey = 100 x 100 x 3 or 4
    Dark Grey = 150 x 100 x 3 or 4
    Orange = 10 mm steel plate
    White = 20 mm aluminum plate
    Blue = ice
    Purple = removable module to be replaceable with 4th axes module in future
    20mm HIWIN rails an all axes

    Click image for larger version. 

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    Any suggestions would be greatly appreciated.

    Last edited by HipoPapi; 20-08-2014 at 05:06 PM.

  5. #15
    starts to look good.

    Some notes:

    - what precision you aim for the cut? Ice will cut, but i see it vibrating if you intend to cut aluminum. It can be made much more rigid if you add some vertical profiles on the gantry, no problem if they are 60x60 and offset from the back gantry plain outwards like 5mm as i remember, so the motor will pass and fit inside the gantry.

    -My suggestion is if you like, to have a look at my new gantry design , there are some cheap improvements over your design especially of the side plates. using profile, can cheapen the build and lessen the time.

    -the table looks like a tank, so good enough for me

    -you must calculate at the end the exact weight of the gantry, cause you can accidentally go in servo territory and or need to drive all with some reduction, which will affect the speed, which will affect the motor choice and drives, etc...

  6. #16
    Hi Silyavsky,

    I have seen your new build log already and looks great and find it a great idea with the air hammer. I have tried to incorporate your gantry design as not having to laser cut would be great, but in my case it doesn't seem to work as it would make the whole machine 200 mm wider which in may case is just wasted space as the ice blocks are always the same size.

    I do not intend to cut other materials than ice with this machine as I have tried on time before and all the filters in the freezer got messed up :)

    well than I guess I have to work out the weight of the gantry ):

    Thanks again.

  7. #17
    One more question.

    at the moment I have left 20 mm of extra rail on all axes in each direction behind where the limit switches would be. So basically when the limit switch stops the movement will still have 20 mm rail left. Is that enough?

  8. #18
    Hello again,

    Has anyone used this calculator before?

    If this is correct although i dont think so as it always gives me round numbers but hopefully is rounding upwards than my gantry without the steppers or servos, and mounts and lead screw, cables and Hiwin reals and blocks is 137 kg therefore I assume with all those added will be around 160 kg.

    Where do I go from here? Please


  9. #19

    Although I have no idea of the stepper or servo size I need nor about the lead screw diameter, what I do know is that I can't find sprocket and chain kits to turn the lead screw with chain instead of belt.
    Does anyone have any suggestions where to look for them?


  10. #20
    Hi Guys,

    I don't seem to be getting a lot of love here but hopefully you can confirm or suggest something better regarding my findings.

    I have emailed around for quotes and had a couple of suggestions.

    The one I am inclined to go for at the moment is the following:

    On the X and Y I would have 2010 ballscrews,
    On the Z 2005 ballscrew,

    On the X and Y I would have Nema 34 easy servo closed loop steppers with 8Nm holding torque(3 phase)
    On the Z I would have Nema 34 easy servo closed loop steppers with 4Nm holding torque

    For drivers I had the following recommended:

    And the following Motion controller:

    The motors would be installed in direct drive and I was given the following results:

    On the X for one stepper the Maximum Thrust would be 3200N (325KG) At 900 RPM (9M/Min). There are two motors on the X so the thrust value should double.

    Please let me know what do you think of the above configuration and some suggestions would be welcome.

    Also if you have some tips of where to introduce some savings please don't hold it in :)


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