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    A lot of discussion here about the cutter forces moving the Z axis up or down, together with possible backlash in X or Y. But there's another one to investigate - which is lifting of the table upwards. Yes, it will be heavy, but with the horsepower and spindle intertia you've got, unless the gibs are tight there could be movement here.

    Wilf



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    Khalid,
    How do you plan on implementing the spindle you will make? Will you remove the current head and mount another or did you have an idea to remove the internal mechanism and replace with a ballscrew actuated drive that would bypass the gears in the head? Just wondering how you planned to do it?

    Regards,

    Regards,
    Wes


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    Wes, Thanks for the feedback about your machines ... 0.005" (0.127mm) is not that good for me... because i want to cut the parts to plus-minus 0.01mm (.0004") .. say for 100mm circular pocket i am looking for 100.01 or 99.99...

    If i get the above , this will be my success..
    Do you have a website? so that i can see more of your work... Do you expect any Retrofit that can give accuracy in the range of 0.01mm,...

    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    Quote Originally Posted by UUU View Post
    A lot of discussion here about the cutter forces moving the Z axis up or down, together with possible backlash in X or Y. But there's another one to investigate - which is lifting of the table upwards. Yes, it will be heavy, but with the horsepower and spindle intertia you've got, unless the gibs are tight there could be movement here.

    Wilf
    hi wilf,
    How the cutter can left the table up?... or lifting of the table upward?... The cross slides (X/Y) is mounted on the Mill-Casted bed, if you have seen the pictures on my posted link... I have 2.5KW Motor attached that run the spindle via gear mechanism and i have enough horse power my Tool will never stop rotating if i dig it into 100mm deep...it will breakapart but never cieze...

    I want more information how the bed can left?

    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    Quote Originally Posted by metalworkz View Post
    Khalid,
    How do you plan on implementing the spindle you will make? Will you remove the current head and mount another or did you have an idea to remove the internal mechanism and replace with a ballscrew actuated drive that would bypass the gears in the head? Just wondering how you planned to do it?

    Regards,
    Okay.. for the spindle i will made exact replica of one of the Spindle installed on my Universal grinder attachment... I will took it apart and make one for my purpose.. I have seen it and is used for endmill, drill grinding and is dead accurate..
    I am planning to remove the existing head and install new column.. On the column i will install Hiwin rails (1.5") and will drive the spindle motor+spindle up/downs with the stepper motor.. Offcourse I have to install the counter weight too...

    Will post the pictures of the progress...

    For ballscrew mode to the existing system, i thinked about it earlier..but again the 0.2mm clearance of the quill not making me try this option.. I really after the accuracy a dead spot accuracy in all axes.. I wish i can get the accuracy in the range of plusminus 0.05mm...

    Last edited by Khalid; 06-04-2010 at 02:27 PM.
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    >>>How the cutter can left the table up?

    Well, if the cutting forces acting on the helix can pull the tool downwards out of the holder, then they are pulling up on the work piece. If I'm milling something held in a vice, and I've not tightened it enough, then the work will come upwards out of the vice and the cutter will dig in. If the machine bed is properly located it can't lift. But if there's any looseness and if it can lift even a little, this will contribute to the problem you're describing.

    Wilfrid



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    Quote Originally Posted by UUU View Post
    >>>How the cutter can left the table up?

    Well, if the cutting forces acting on the helix can pull the tool downwards out of the holder, then they are pulling up on the work piece. If I'm milling something held in a vice, and I've not tightened it enough, then the work will come upwards out of the vice and the cutter will dig in. If the machine bed is properly located it can't lift. But if there's any looseness and if it can lift even a little, this will contribute to the problem you're describing.

    Wilfrid

    hi Wilfrid,
    Today i checked all the things and they found tight. With the same settings as yesterday, i just plot 100mm Diameter circle and 150mm Square. The backlash for all the Axes was enabled. The circle meets all the points and were found round within 0.01mm. The Square was perfect within the 0.01mm. and the start and end point meets exactly...

    This tells me that i have no motors as well as backlash calibrations issues in no-load conditions.

    PS:
    The circle was drawn first with Lead pencil and i measured it. but when drawing the square the pencil stopped marking. So i install the Pen, this work perfect for Square drawing but torn the page while drawing the circle.

    Any thought?

    Attached Thumbnails Attached Thumbnails Milling Cast Iron-dsc05169-jpg  
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    Default Additional information

    Backlashs for Axes:
    1- X-axis: 0.005708 inch = 0.145mm
    Y-axis: 0.013385 inch = 0.334mm
    Z-axis: 0.0535433 inch = 1.36mm
    Backlash speed of max%: 50%
    shuttle Acceleration:0.08
    Mill : climb mill

    Calibrated Step/units(mm) : calibration was taken at 290mm length with needle gauge and gauge blocks
    X-axes: 6093.32125758
    Y-axis : 6093.32125758
    Z-axes: 15177.80388
    Kernel Speed: 25000Hz


    I am running the steppers in 1/2 step mode.. Do we have any problem with the steps i mentioned above?

    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    Hi Guys
    As i have shown you the 45 degree square and the Circle..I have perfect all the things..but today when i tested on Aluminum i found some trouble as you can see in picture..
    It is the picture of a simple 5-vane open impeller just to check the machine behaviour on the Aluminum... As you have seen in the picture, the simulation perfectly shows the same resultss of my Gcode.. I am annoyed only because i am going out of my centre.. As you have seen the picture one of the Vane just at the edge of the stock... All the dimensions are perfect..and this is very strange for me..if the motor looses steps then the Vane thickness and curvature must be different but in this case it is the same thickness.. I stopped the machine when the cutter strike the clamp.. If the part was completed then may be i had some clue why this happen?

    The part dmension is 110mm, the stock used was Aluminum 121mm dia 21mm thickness.. The pocket was done in 4-passess upto 8mm depth with 7 IPM and 800 RPM using new 8mm 2-flute HSS endMill..
    Any thought?


    PS:

    SHOULD I SAY, THAT THE TOOL IS GOING OUT OF CENTRE? ... A little confusing to me... Seems that stock is offset to the Geometry in the CAM software.. But when i saw in the CAM the geometry is centred in the STOCK...... i am confused because thee impeller machining and dimension is right after removal of the part.. It seems that i have some offset of the complete part in the stock.. Help me i am in a very perplexing situation... Anything in MACH3 that can cause this???


    Attached Thumbnails Attached Thumbnails Milling Cast Iron-dsc05174-jpg  
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    http://my-diysolarwind.blogspot.com/


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    Default Simulation VS Actual

    Here is the Simulation results and Actual - side by side... The simulator is new to me so i can't color map the depth...

    Attached Thumbnails Attached Thumbnails Milling Cast Iron-simulation-vs-actual-jpg  
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


  11. #31
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    Quote Originally Posted by Khalid View Post
    Backlashs for Axes:
    1- X-axis: 0.005708 inch = 0.145mm
    Y-axis: 0.013385 inch = 0.334mm
    Z-axis: 0.0535433 inch = 1.36mm
    Backlash speed of max%: 50%
    shuttle Acceleration:0.08
    Mill : climb mill




    I am running the steppers in 1/2 step mode.. Do we have any problem with the steps i mentioned above?

    you should be conventional milling with that much slop

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    Khalid, some thoughts:

    - That the paper is torn sometimes and sometimes not makes me wonder how well trammed this machine is. The axes may not be very square relative to one another or the table.

    - Dertsap is right about avoiding climb milling. You have a lot of backlash. Ultimately too much to achieve the accuracy you want of less than half a thousandth. This is probably not the machine for that kind of accuracy.

    - Take much lighter depths and widths of cut where possible. Your machine doesn't seem very rigid, so you have to reduce cutting forces on it as much as possible.

    - You haven't told us much about how you are plunging your tool into the cut. If you plunge vertically, at what speed? Try using your normal feedrate divided by the number of flutes. You should prefer a helical or ramped entry if your CAM software supports it.

    - How are you clearing chips? I see what looks like a coolant try, but no idea if you have flood coolant, and air blast, or what. Cast iron needs no coolant, but you have to clear the chips with an air blast at the very least.

    Cheers,

    BW

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    Quote Originally Posted by BobWarfield View Post
    Khalid,
    . You should prefer a helical or ramped entry if your CAM software supports it.

    BW
    I agree , i absolutely despise plunging end mills , ramp and helical entry are faster and are less abusive
    because of the amount of slop helical would be the better choice in keeping a constant (or somewhat consistent) pressure on the tool , inconsistency of tool pressure will affect the cuts
    overall most cast is like butter compared to most other materials , so under the right conditions you should be able to be extremely aggressive with it as far as speeds and feeds , depths and engagement

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    Quote Originally Posted by dertsap View Post
    I agree , i absolutely despise plunging end mills , ramp and helical entry are faster and are less abusive.
    dertsap, I became a confirmed believer after literally feeling the difference in my own two hands on a manual mill. It's a worthwhile experience if you get the chance. Just feel the pressures on the handwheels as you ramp in versus plunging. Heck just the sound from most lighter mills is telling you what the mill prefers.

    OTOH, it takes a man with some coordination and a unique anatomical arrangement to crank the 3 handwheels simultaneously needed to do a helical entry manually!

    I have heard hot rodding stories of shifting with one's right knee while operating both pedals, the steering wheel, and keeping one arm free for your girl friend, so maybe it's possible.

    Cheers,

    BW

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    once again i agree but i thought that we were talking cnc here

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    Quote Originally Posted by BobWarfield View Post
    Khalid, some thoughts:

    - That the paper is torn sometimes and sometimes not makes me wonder how well trammed this machine is. The axes may not be very square relative to one another or the table.
    First I am thankful for answering.. I didn't check the level of the table, but I am sure it need tramming as you have observed in Paper torn case.. I was standing behind the machine ans saw some where PEN has very less pressure and some where pen has more pressure on the paper...

    Actually the paper was pasted on a Round Flat SS workpiece (That was rounded and faced on lathe at both side)... Tomorrow I will installed the Dial on the Z-axis and will check the Flatness of the table...
    Quote Originally Posted by BobWarfield View Post
    - Dertsap is right about avoiding climb milling. You have a lot of backlash. Ultimately too much to achieve the accuracy you want of less than half a thousandth. This is probably not the machine for that kind of accuracy.
    The backlash compensation was done in Mach3 using the technique used in Your videos across the complete length of the cross slides.. I used exact method you have thought us in your videos using Gauge Blocks and Needle Dial Guage...Using yours great videos and technique i was able to get 0.01mm tolerances in the Circle and rotated square with no sign of backlash.. I afraid that this is done in no-l;oad condition... But if Mach3 compensate the backlash then the problem should not appear in actual work piece...

    One other thing i want to share here, is that i installed the tip of the dial guage on the tooltip.. and gave lateral movement to the quill i was getting 0.5mm flex... so total flex will be 1mm that will appear in workpiece..

    This is the reason I am currently making drawings of a spindle... and will change the complete Z-axes...

    Do i have to rework on my X/Y cross slides?.. These slides are boxway type and very rigid.. I feel no vibration in them.. Just to check the Tramming tomorrow...
    [/QUOTE]
    Quote Originally Posted by BobWarfield View Post
    - Take much lighter depths and widths of cut where possible. Your machine doesn't seem very rigid, so you have to reduce cutting forces on it as much as possible.
    Again , i don't know why my Z-axis goes down in the work piece... In CAM i gave 2mm DOC/Pass for the above Aluminum part and the first Pass i measured was about 3.5mm.. there is some clearances in the Quill i think that once adjusted for the first pass and then for the next consequent passes it gives me exact DOC...

    Quote Originally Posted by BobWarfield View Post
    - You haven't told us much about how you are plunging your tool into the cut. If you plunge vertically, at what speed? Try using your normal feedrate divided by the number of flutes. You should prefer a helical or ramped entry if your CAM software supports it.
    I plunge the Tool using Ramping technique..
    Ramp ANgle= 10mm
    Ramp Height= 12mm
    Ramp distance= 10mm

    CAST IRON:
    The speed is 2 IPM only for CAST Iron and the cut was done 3 IPM for Cast Iron , the spindle speed was 800 RPM and the tool was 10mm HSCo 2-Flutes end mill..

    ALUMINUM:
    The same ramp with 5IPM and the cutting speed was 8 IPM, using HSco 2Flute 8mm end Mill...

    However the software also support Helical ramping...

    Quote Originally Posted by BobWarfield View Post
    - How are you clearing chips? I see what looks like a coolant try, but no idea if you have flood coolant, and air blast, or what. Cast iron needs no coolant, but you have to clear the chips with an air blast at the very least.

    Cheers,

    BW
    For both the parts mentioned above i used Flood Coolant.. and the coolant is abundant with 3-Nozzles jet.. I never saw that much coolant used by any
    other machine in my workshop...


    I am thankful you looked into the matter and helped me... I am sure that the cross-slides Gibs are tight and the Motor Pullys are Keyed... so no slip is possible...I am using the stepper motors with 36Volts and about 3.6Amp... I have connections available at my power supply upto 70Volts..

    Last edited by Khalid; 06-06-2010 at 02:40 AM.
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/


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    Quote Originally Posted by dertsap View Post
    I agree , i absolutely despise plunging end mills , ramp and helical entry are faster and are less abusive
    because of the amount of slop helical would be the better choice in keeping a constant (or somewhat consistent) pressure on the tool , inconsistency of tool pressure will affect the cuts
    overall most cast is like butter compared to most other materials , so under the right conditions you should be able to be extremely aggressive with it as far as speeds and feeds , depths and engagement

    hI cURT,
    Thanks for answering.. I am new in Metal cutting so lot of problems i will face... However with the help of this community and metal cutting gurus will help me...

    I am attaching the picture.. The round circle is a pocket and this pocket is spiral... The table rotates CW and tool rotating Anti-clockwise.. Is this right?.. Or i have to move the tool along the table i.e. both Anticlockwise ?

    My Spindle motor is 2.2KW 3Phase and drive the spindle with gearing mechanism... So far i never see my tool is stopped due to less RPM or very high load on the cutter...

    Attached is the Gcode for the Aluminum Impeller..

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  18. #38
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    Quote Originally Posted by Khalid View Post
    I am attaching the picture.. The round circle is a pocket and this pocket is spiral... The table rotates CW and tool rotating Anti-clockwise.. Is this right?.. Or i have to move the tool along the table i.e. both Anticlockwise ?

    ..
    reverse the cut direction in the impeller g code that you created , for cutting inside of lets say a pocket your cutting path should be clockwise and for outside it should be counter clockwise

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


  19. #39
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    Hi Curt..
    Also can you tell me whats wrong with shifting the impeller in stock? You have seen all the pictures and i have not found what was the problem?..
    Is it problem of loosing step?
    Is it problem of wrong calibration?
    or What?

    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
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    to be honest its hard to say , it looks like missed steps but it could also be a result of the part being jerked around because of the backlash , i'd suggest cutting a circular pocket with conventional milling then cut another circular pocket with climb milling and compare the results , better yet try a pocket with a small island in the center
    it may take some experimentation to figure out where your machine will be temper mental and then you can possibly compensate from there

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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