CNC router build - Page 2


Page 2 of 33 FirstFirst 1234512 ... LastLast
Results 13 to 24 of 394

Thread: CNC router build

  1. #13
    Member handlewanker's Avatar
    Join Date
    Sep 2006
    Location
    Australia
    Posts
    6181
    Downloads
    0
    Uploads
    0

    Default Re: CNC router build

    Hi, I quite agree with the moving table design as it can be made more sturdy especially if you want to get ambitious and do a bit of steel milling.

    I hypothesised with a different aspect ratio design for the table size, as the table Y axis length does make the base twice as long as the table due to spindle coverage etc..

    Taking a 6040 for example.....in a moving gantry design the table is narrow ....400mm wide and passes under the gantry, but with a moving table type the base would be 1.2 metres long to allow the table to traverse it's 600mm length.

    You could make the table Y axis the 400mm width and make the X axis the 600mm length which means the X axis crossbeam has to be only a bit over the 600mm wide to allow the spindle to move over the table length sideways.

    If the 600mm table length does not pass between the gantry uprights the head has to stick out a long way from the X axis face to cover the 400mm table width.

    So, as the uprights and crossbeam can be massive, it would be practical to allow the table to move a short distance under the crossbeam but not necessarily all the way as in a moving gantry type......this would reduce the spindle stick out from the X axis face quite a bit.

    At no time would you want a long job to overhang the table sides.....it can overhang on the 400mm width as that is now the Y axis.

    I think a table rapid travel in a 400mm Y axis can be a lot quicker than the corresponding normal 600mm table length......it's unconventional, but could be practical to keep the base length more compact.
    Ian.



  2. #14
    Registered
    Join Date
    Apr 2013
    Location
    Sweden
    Posts
    1851
    Downloads
    2
    Uploads
    0

    Default Re: CNC router build

    Quote Originally Posted by ericks View Post
    What i found to be the major problem is the open pillow blocks on my machine's y-axis.
    If your machine is similar to the one in the pictures than your problem is not the pillow blocks, unless you have some with manufacturing issues or badly aligned. The problem is most probably the fact that it is a moving gantry design. I am using similar supported round rods with open end pillow blocks and have absolutely no problems at all, get very high speed and accuracy and very happy with it. The big difference is that I decided to build a fixed gantry, moving table type of machine, not what is most popular, the moving gantry type, which is more difficult to align, difficult to get the speed and accuracy right and is easy to get gantry vibrations and misalignment with.

    Quote Originally Posted by ericks View Post
    Here is what i have come up with thus far...

    1) Clamping area 1200 mm x 850 mm.
    2) 80 x 80 mm Aluminium profile for frame and table
    3) Two 1610 ball screws for y-axis
    4) Four HGH25CA linear blocks for y-axis
    5) 20 mm side plates/brackets
    6) 25 mm (unsupported) round shaft for x-axis
    7) four linear bearings for x-axis.
    8) Additional 25 mm shaft added for rigidity of the x-axis
    9) 1605 ball screw on x-axis
    10) 1605 ball screw on z-axis
    11) 16 mm unsupported round shaft on z-axis
    12) Four linear bearings on z-axis
    12) Nema 23 stepper motors
    The above parts list is fine, with a few exceptions.

    Don't use ANY unsupported round rods (items 6 and 11). Why do you think that 25mm unsupported round shafts will be better than 16mm supported ones? They are NOT better.
    What is the item 8 exactly do and where is it located? I don't understand that and the purpose of it.

    Consider moving table fixed gantry design, and also remember that slaved motors can be a problem as well, they might cause the same sort of issue with accuracy unless you have very accurate ball screws and nuts. I am using 1605 on all three axes and have only one on the Y also, which is my table. My frame is build mainly with 45x90 and used 30x60 for some parts. Also already now make a decision about the electrical parts, driver and controller software. Talking about electrical parts... I'd replace the Kress with a real VFD controlled spindle Even an air cooled 1.5kW would do better than that Kress, which really is only a high quality angle grinder. Even if you are not willing to throw it away, design the Z so that one day when you decide to get a real spindle you could easily install it. The Z is the most important part of a machine. If you get it right half of the battle is won, but the Z includes the spindle as well.

    If you want to have a look at my specifications you can visit this post:

    https://adapting-camera.blogspot.se/...nt-status.html

    I don't have a real build log, but on my blog you can find many posts regarding my building progress.

    [url]https://adapting-camera.blogspot.com[/url]
    [url]https://www.youtube.com/c/AdaptingCamera/videos[/url]


  3. #15
    Registered
    Join Date
    Apr 2013
    Location
    Sweden
    Posts
    1851
    Downloads
    2
    Uploads
    0

    Default Re: CNC router build

    Quote Originally Posted by handlewanker View Post
    Hi, I quite agree with the moving table design as it can be made more sturdy especially if you want to get ambitious and do a bit of steel milling.

    I hypothesised with a different aspect ratio design for the table size, as the table Y axis length does make the base twice as long as the table due to spindle coverage etc..

    Taking a 6040 for example.....in a moving gantry design the table is narrow ....400mm wide and passes under the gantry, but with a moving table type the base would be 1.2 metres long to allow the table to traverse it's 600mm length.

    You could make the table Y axis the 400mm width and make the X axis the 600mm length which means the X axis crossbeam has to be only a bit over the 600mm wide to allow the spindle to move over the table length sideways.

    If the 600mm table length does not pass between the gantry uprights the head has to stick out a long way from the X axis face to cover the 400mm table width.

    So, as the uprights and crossbeam can be massive, it would be practical to allow the table to move a short distance under the crossbeam but not necessarily all the way as in a moving gantry type......this would reduce the spindle stick out from the X axis face quite a bit.

    At no time would you want a long job to overhang the table sides.....it can overhang on the 400mm width as that is now the Y axis.

    I think a table rapid travel in a 400mm Y axis can be a lot quicker than the corresponding normal 600mm table length......it's unconventional, but could be practical to keep the base length more compact.
    Ian.
    I agree that it is better to have the X as 600mm and Y as 400mm long and that the gantry beam should go over the longer part of the table in this case.

    On the other hand, if the table is needs to be moved 600mm the machine will require MORE than 1200mm floor space. My work area is 300x250mm and the total floor area the machine takes is 750x650mm, including all the extruding parts, like steppers and frame. But it is important to note that even a moving gantry type of machine with a work area of 600x400mm would require more than 600x400mm floor space. Generally I think that a moving table type of machine requires about 1/3 more space than a moving gantry type, but as been pointed out, a moving table type has some advantages also.

    [url]https://adapting-camera.blogspot.com[/url]
    [url]https://www.youtube.com/c/AdaptingCamera/videos[/url]


  4. #16
    Registered
    Join Date
    Oct 2005
    Location
    australia
    Posts
    255
    Downloads
    0
    Uploads
    0

    Default Re: CNC router build

    Have a look at these vids. he covers a lot of cancepts and mistakes. The secret is what tools you have in your workshop,

    Also for Z axis plate https://us.misumi-ec.com/vona2/detail/110300540610/ Basically design around the components and then build a frame to hold it all in place. stiffness is your friend regarding tool load and mass will need bigger drive motors.
    Paul



  5. #17
    Member handlewanker's Avatar
    Join Date
    Sep 2006
    Location
    Australia
    Posts
    6181
    Downloads
    0
    Uploads
    0

    Default Re: CNC router build

    I'm going to be completely heretical here......the biggest draw back of any gantry type CNC router is the Z axis clearance under the crossbeam.......too low and you won't machine jobs with vices etc.....too high and you have the cantilevered forces of the cutter acting on the X axis cross beam to twist it or flex the Z axis hung down slides etc.

    So, if you have two vertical side members that are massive in cross section....why not mount linear rails on them and raise and lower the complete X axis assembly instead of just the Z axis.

    This will give you a solid mounted saddle on the X axis slides that does not have to stick out as much or hang down at it's lowest travel like the conventional Z axis does.

    I worked on planer mills back in the 60's and they were of this construction

    This configuration is like a column mill but with two columns either side of the table.

    A conventional column mill has one column and the head moves up and down on it and has to stick out far enough to cover the width of the table when close to the column.

    I propose to have two ball screws, one on each column side, to drive the cross beam up and down with gas struts to counter the cross beam and spindle weight.

    The hollow head casing would have an integral 3/4 HP 3 phase 3,500 rpm motor speed controlled with a VFD and a 2 step Poly vee belt drive to give a speed range of 0 to 7,000 rpm.

    I've already done a rough sketch feasibility study to see if the configuration would be practical.

    It would be wide to cover the 600mm table length X axis move, but also more compact for the 400mm Y axis move.
    Ian.



  6. #18
    Member
    Join Date
    Mar 2013
    Location
    United States
    Posts
    140
    Downloads
    0
    Uploads
    0

    Default Re: CNC router build





  7. #19
    Member handlewanker's Avatar
    Join Date
    Sep 2006
    Location
    Australia
    Posts
    6181
    Downloads
    0
    Uploads
    0

    Default Re: CNC router build

    LOL........thanks, nothing is new under the Sun.....the twin linear rail Z axis concept is a winner I think even though the design is a moving gantry type.....looks pretty impressive.......peck drilling might be a problem for small drills etc.
    Ian.



  8. #20
    Member
    Join Date
    Jun 2017
    Location
    Australia
    Posts
    823
    Downloads
    0
    Uploads
    0

    Default Re: CNC router build

    I appreciate every single bit of advise from everybody



  9. #21
    Member
    Join Date
    Jun 2017
    Location
    Australia
    Posts
    823
    Downloads
    0
    Uploads
    0

    Default Re: CNC router build

    Quote Originally Posted by A_Camera View Post
    If your machine is similar to the one in the pictures than your problem is not the pillow blocks, unless you have some with manufacturing issues or badly aligned. The problem is most probably the fact that it is a moving gantry design. I am using similar supported round rods with open end pillow blocks and have absolutely no problems at all, get very high speed and accuracy and very happy with it. The big difference is that I decided to build a fixed gantry, moving table type of machine, not what is most popular, the moving gantry type, which is more difficult to align, difficult to get the speed and accuracy right and is easy to get gantry vibrations and misalignment with.



    The above parts list is fine, with a few exceptions.

    Don't use ANY unsupported round rods (items 6 and 11). Why do you think that 25mm unsupported round shafts will be better than 16mm supported ones? They are NOT better.
    What is the item 8 exactly do and where is it located? I don't understand that and the purpose of it.

    Consider moving table fixed gantry design, and also remember that slaved motors can be a problem as well, they might cause the same sort of issue with accuracy unless you have very accurate ball screws and nuts. I am using 1605 on all three axes and have only one on the Y also, which is my table. My frame is build mainly with 45x90 and used 30x60 for some parts. Also already now make a decision about the electrical parts, driver and controller software. Talking about electrical parts... I'd replace the Kress with a real VFD controlled spindle Even an air cooled 1.5kW would do better than that Kress, which really is only a high quality angle grinder. Even if you are not willing to throw it away, design the Z so that one day when you decide to get a real spindle you could easily install it. The Z is the most important part of a machine. If you get it right half of the battle is won, but the Z includes the spindle as well.

    If you want to have a look at my specifications you can visit this post:

    https://adapting-camera.blogspot.se/...nt-status.html

    I don't have a real build log, but on my blog you can find many posts regarding my building progress.
    Hi, my problem with the supported shaft is not the shaft itself. It's the "open" bearing that runs on it. When i put pressure on the x-axis then there is movement on the bearing...it actually distorts.
    I guess a better quality bearing would fix the problem.



  10. #22
    Member
    Join Date
    Jun 2017
    Location
    Australia
    Posts
    823
    Downloads
    0
    Uploads
    0

    Default Re: CNC router build

    Quote Originally Posted by handlewanker View Post
    Hi, I quite agree with the moving table design as it can be made more sturdy especially if you want to get ambitious and do a bit of steel milling.

    I hypothesised with a different aspect ratio design for the table size, as the table Y axis length does make the base twice as long as the table due to spindle coverage etc..

    Taking a 6040 for example.....in a moving gantry design the table is narrow ....400mm wide and passes under the gantry, but with a moving table type the base would be 1.2 metres long to allow the table to traverse it's 600mm length.

    You could make the table Y axis the 400mm width and make the X axis the 600mm length which means the X axis crossbeam has to be only a bit over the 600mm wide to allow the spindle to move over the table length sideways.

    If the 600mm table length does not pass between the gantry uprights the head has to stick out a long way from the X axis face to cover the 400mm table width.

    So, as the uprights and crossbeam can be massive, it would be practical to allow the table to move a short distance under the crossbeam but not necessarily all the way as in a moving gantry type......this would reduce the spindle stick out from the X axis face quite a bit.

    At no time would you want a long job to overhang the table sides.....it can overhang on the 400mm width as that is now the Y axis.

    I think a table rapid travel in a 400mm Y axis can be a lot quicker than the corresponding normal 600mm table length......it's unconventional, but could be practical to keep the base length more compact.
    Ian.
    That was the first thing i realized about the fixed gantry design, the length of the machine...



  11. #23
    Registered
    Join Date
    Apr 2013
    Location
    Sweden
    Posts
    1851
    Downloads
    2
    Uploads
    0

    Default Re: CNC router build

    Quote Originally Posted by ericks View Post
    Hi, my problem with the supported shaft is not the shaft itself. It's the "open" bearing that runs on it. When i put pressure on the x-axis then there is movement on the bearing...it actually distorts.
    I guess a better quality bearing would fix the problem.
    There are two screws in each bearing to remove the play. Mine are 16mm but I can NOT feel any movement and definitely no distortion.

    [url]https://adapting-camera.blogspot.com[/url]
    [url]https://www.youtube.com/c/AdaptingCamera/videos[/url]


  12. #24
    Registered
    Join Date
    Apr 2013
    Location
    Sweden
    Posts
    1851
    Downloads
    2
    Uploads
    0

    Default Re: CNC router build

    Quote Originally Posted by ericks View Post
    That was the first thing i realized about the fixed gantry design, the length of the machine...
    ...the calculation is wrong in that link. A moving table type requires more space than a moving gantry type, but not twice more, only about 1/3.

    [url]https://adapting-camera.blogspot.com[/url]
    [url]https://www.youtube.com/c/AdaptingCamera/videos[/url]


Page 2 of 33 FirstFirst 1234512 ... LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

CNC router build

CNC router build