HELP! 5-Axis 4'x4'x30" CNC Router - Page 2


Page 2 of 3 FirstFirst 123 LastLast
Results 13 to 24 of 34

Thread: HELP! 5-Axis 4'x4'x30" CNC Router

  1. #13
    Gold Member
    Join Date
    Apr 2009
    Location
    USA
    Posts
    5046
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by ger21 View Post
    No, I haven't had time to follow the development.
    I just looked, and 3+1 and 3+2 has been available for several months now, and continuous 5 axis is coming. Might be a year, maybe longer, but should be available within a year or so I would think. Autodesk said they were working on it 6 months ago from the roadmap I saw.

    I thought a 1 year license of 5 axis Fusion came with the PocketNC machine...

    Another option would be DeskProto, but it's only 5th axis positioning not continuous...



  2. #14
    Gold Member daniellyall's Avatar
    Join Date
    Sep 2009
    Location
    New Zealand
    Posts
    1666
    Downloads
    3
    Uploads
    0

    Default Re: HELP! 5-Axis 4'x4'x30" CNC Router

    It's meant to come with fusion ultimate Lou, startup under 100k is free, hobby is free per year, student is 3 years free this is all ulitmate. you can only get standard by paying for it, its 3 axis only.

    You can ball**** the wrapping useing sketches to do continuous on certain geometry types.

    http://danielscnc.webs.com/

    being disabled is not a hindrance it gives you attitude


  3. #15
    Gold Member
    Join Date
    May 2005
    Location
    USA
    Posts
    3118
    Downloads
    0
    Uploads
    0

    Default

    Your reply might have been harsh but i think the BS detector was right on. The reference to doing FEA and the indication that the machine would be rigid enough had me shaking my head and im nit even a FEA expert.

    Now that being said i think we can get them on track to a successful design. We do need to cut through the BS though.

    Quote Originally Posted by NIC 77 View Post
    I’ve always appreciated your input whenever I’ve had a question. I admit I was a bit harsh in my response. I certainly don’t want to make enemies on this forum. If I’ve offended you Louie, which I think I have, then I sincerely apologize to you.

    When I took a second look at it, all the talk of CAD models and FEA analysis, cutting aluminum, confidence in abilities to make the system rigid, and a working shop that manufactures for aerospace, my BS sensor engaged.

    And then I looked at the design again and there are two bearings for the Z axis attached by 2 inch square tube at a right angle, and I thought, OMG, this can't be true, I've been had.

    I started wondering if this was perhaps posted by someone in China who was looking to advertise their product without overtly doing so.

    I certainly wouldn’t have made the comment that I did if this was posted as a beginner making a 5 axis hobby machine.

    Look, we all make mistakes and sometimes say things that are too harsh. I’m human. I do this sometimes. This is probably one of those times for me.

    Scott, if it turns out that I am wrong, then I will apologize to you as well.

    Good luck with whatever you do. Louie has more experience than me, and has given you good advice.

    The only other thing I will say is that if you’re for real then perhaps it's better to buy something and adapt it to your needs. I was looking at a thread earlier about a “Saturn” CNC machine from finelineautomation. Looked very nice. Perhaps you could ask them to make you one where the table sits much lower.

    Of course, I don't know if they ship to China.

    Apologies to everyone for the harsh nature of my earlier response.




  4. #16
    Gold Member
    Join Date
    Apr 2009
    Location
    USA
    Posts
    5046
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by wizard View Post
    Your reply might have been harsh but i think the BS detector was right on. The reference to doing FEA and the indication that the machine would be rigid enough had me shaking my head and im nit even a FEA expert.

    Now that being said i think we can get them on track to a successful design. We do need to cut through the BS though.
    I'm not so sure... I've seen a few FEA done on YouTube usi g Fusion360 and it put out results that surprised me.



  5. #17
    Gold Member
    Join Date
    May 2005
    Location
    USA
    Posts
    3118
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by ScottMcCormick View Post
    Hey CNC junkies,

    Let me first start off by saying that there is no build that is impossible. That being said, I've heard a lot of people state that this build is impossible,
    You can build anything the question is will it meet your expectations. Im going to say right off this machine will have trouble with anything beyond foam.

    but CAD models and FEA suggest that it may be feasible within our desired tolerances (+/- 0.003"). I plan on using this thread as a method of documenting the design for others to collaborate, and ask questions about the design as we run into problems.
    How much experience does your FEA guy have? I ask because i highly doubt the Z woild hold postion that you want being pushed by my pinky. 30" of Z is a seriously long lever arm, as designed it is going to deflect mire than thr 0.003" you are asking for under load. Not to mention issues with vibration.

    This is based on industtial experience with all sorts of machinery not FEA. In any event to clarify communications here, im going to refer to the acises as X, Y, Z from bottom to top. (It is a pet peeve to be sure)

    In any event your lever arm is long enough that i suspect you will get deflection out of the X axis frame members, especially in the center. In other words your frame is pretty weak for the tolerances you are trying to achieve.
    Our shop is looking to design and fabricate a 4'x4'x30", 5-axis CNC router that will do 70% foam, wood, composite work and 30% light aluminum work. The proposed budget is currently at ~$10K-$15K.
    Well at least your budget is some what realistic. Given reasonable budgetting i would strongly suggest beefing up with respect to your steel members. You might want to run FEA but id suggest at a minimal 3" square tubing for the frame and even that might be thin. The good thing with the frame is that you are free to reinforce it as you see fit. Id certainly add more bracing but then you need a way to load the machine. Honestly with a 4' span id seriously consider 4" square tubing
    We are in the aerospace industry, so we work with aircraft tolerances, which means this machine has to be very rigid. We are using 4"x4"x0.25" ASTM A500 Grade B Steel for the frame, and 2"x2"x0.120" steel tubing for the structural members.
    .
    That is one very confusing statement. The frame is a structural member, so is the frame 2" tubing or 4". Also use tubing that is as thick as you can source. The thickness may not impact your machines rigidity that much but it will do wonders for screw holding which can eliminate the need to weld pads for bolted on components.

    In any event your gantry beam needs to be far larger. There is an excellent thread in the stickies that covers gantry beam design. Your problem here is the long lever arm of the Z axis which will twist the beam.
    The bed will be made out of a dense wood or composite material, and will include a lattice structure style torsion box.
    If you are buying steel buy a piece of blanchard ground steel and suppirt it with steel matching the rest of your frame members. The thing here is that the minute you start machining aluminum you will want to use coolants/lubes. This will raise hell with wood based structures.
    We will be implementing a dual-driven gantry, also made out of steel, and we plan on using rack and pinion drives (the kit from cncrouterparts.com) for the X, Y axes that drive the gantry and Z-axis assembly.
    Why rack and pinion? For a machine this size and the tolerances wanted anti backlash screws are in order.
    The Z-axis itself will be driven using a 48" ballscrew. The gantry and X-axis will traverse along Hiwin Profile Rail guides, and the Z-axis will traverse along continuously supported shafting.
    You have a realtively robust budget so why cheap out on linear bearings? The Z is probably the last place you would want to use round rails.
    The 4th and 5th axis capabilities will come from the Doughty Drive B/C rotary head. I am confident in our abilities to make this system rigid, and for the mechanical and structural systems to be sound.

    What I am less confident in, and is the problem we are currently facing, is the electronics and wiring system. We plan on using NEMA34 motors to dual drive the gantry along the Y-axis, to drive the Z-axis assembly (cutting arm) along the X-axis, and the Z-axis ballscrew itself. We will use NEMA23 motors to drive the B/C axes on the head itself in which the spindle sits. That gives us 6 axes to control, and I'm unsure of what control board we will need. I have done some research, and found a 6 axis control board, but I'm worried that this won't allow for the 3 axes + the slaved axes for the gantry, as well as the 2 rotary axes. Does anyone have any experience with this, or know if this will work? We are going to use Mach 3.
    You may want to completely reconsider this. Frankly it is better to put off electronics untill you have a good idea of what the final mechanical design is.
    In summary, I have a few questions for those of you who've done this before:
    - Will the 6 axis control board I've posted a picture below handle what we are trying to achieve?
    - Suggestions for spindle head (air cooled, water cooled, 2.2kW?, etc.). Completely newbie to this part of the design.
    - Software for generating the toolpath and gcode for 5-axis capabilites (I've heard cnc-toolkit, AutoDesk Fusion)?
    - Other tips for the electronics side of things; again, complete newbie with this aspect of the design
    This is a tough one because if you are serious about precision you will likely need linear encoder feed back. This puts you into a different class of controller than is commonly discussed here. You need to nail down your specs a bit more. If you want to hold position to 0,003" over 4' you will need linear scales as the most economical way to achieve that. Im not sure what your real needs are here.
    Any constructive criticism or suggestions are welcome and appreciated. This is turning out to be a huge endeavor, but I'm enjoying it and I believe that the final product will pay off.
    Such a project isn't impossible however dont underestimate the extra efforts required to do something that isn't mainstream. DIY 5 axis machines aren't mainstream yet. This means some trail blazing on your own.

    You need to consider how the machine will go together and what local machining resources you have. To be perfectly honest you could get away with foam machinig with only a few enhancements. Once beyond that though i suspect you will have trouble. But back to the machine itselfhoe the machine is assembled becomes an issue in getting goid results.

    First you will want to consider having the frame stress relieved. Second you will want to find a shop with a mill large enough to mill the mounting pads for the linear rails. You may even need to have pads welded to the frame to have enough material to mill the pads in place.

    This is all based on your rather tight precision requirments. It would be rather easy for a welded frame to distort sometime after assembly causing you accuracy problems.

    You also have the issue of getting the table parallel to the gantry and X axis. This might require a two piece frame.
    I've posted a few visuals from our current design iteration to hopefully help clear things up.
    Im not getting a warm and fuzzy feeling here. The gantry just doesnt look robust for work in aluminum.


    Note: the models are very preliminary, most of the mates and geometry are there, but some components like the rack and pinion drive are not in their final places.

    Please help if you can!

    - Scott
    I hope that i have helped some. My biggest fear is that the machine wont meet your needs in aluminum and maybe even wood. This mainly due to 0.003" being tight on most routers. When you combine a long lever arm with rack and pinion drive and some other design choices i dont see happyness.

    By the way a decent fifth axis head could be an issue here. This especially if you really want to swing around a 2kw spindle motor. You can blow your budget right here. You may also find yourself having to DIY the fifth assembly to get the results you want. 2kwof power is a lot in alow end fifth axis solution.

    Which brings up a final considerstion do you really need the large spindle? Im assuming that you want that large of a spindle because you expect to use all of that power. Only you know how you expect to use the machine but the fact is if you are using all of that power you will be causing reaction forces that will deflect your Z. Not to mention the forces on the Fith extension.

    One other thing here now that we have considered the spindle. Your frame has to be large enough to clear the spindle in all orientations which becomes worse with the larger and longer spindles. If you don't factor this in then you loose a significant amount of work area. Not to mention the damage each crash will cause.

    Somebody else mentioned a moving table design. This may be a good idea and might actually save you space that would be otherwise used up by an oversized frame. With your design your frame has to be oversized enough to alliw the spindke to clear all four cumns. On a moving table design you could design in clearance around the suppirt columns. Even if you found yourself spreading the two columns out you still wouldn't lose width for the entire machine. Even lengthwise a moving table wouldnt be that bad because your saddles the gantry beam rides on need to be fairly wide to resist the forces involved. This all adds up such that a moving table design might make sense even at this larger scale.

    A moving table design may also solve the prblem of liading and unliading the machine and also address ease of tool changes. Tool changes will be intererting with you design as you will likely have to reach a considerable distance.

    Hope this helps.



  6. #18
    Gold Member
    Join Date
    Apr 2009
    Location
    USA
    Posts
    5046
    Downloads
    0
    Uploads
    0

    Default Re: HELP! 5-Axis 4'x4'x30" CNC Router

    Quote Originally Posted by wizard View Post
    Your reply might have been harsh but i think the BS detector was right on. The reference to doing FEA and the indication that the machine would be rigid enough had me shaking my head and im nit even a FEA expert.

    Now that being said i think we can get them on track to a successful design. We do need to cut through the BS though.
    If there's one thing I've learned in 20 years of participation in online forums, is to never, ever assume or make judgment upon, the intentions of the OP. It's so easy, as it turns out, to fall into this trap, and I've admittedly done so on occasion; happens to the best of us. The term "aerospace" can be pretty broad and it doesn't always mean milling a bulkhead out of a gigantic billet of 7050. I t could be taking a stamping or formed sheet metal and cutting holes or ports into it. He could be a startup. And like I said, I've seen some FEA results with Fusion360 posted online that gets my head itchy. One for example recently where the designer is using relatively small rectangular steel tubing, with 16 or 20mm supported round rod and open round bearing blocks, and claims all the bending on the machine is at the carbide endmill that was modeled, with absolutely no deformation anywhere on the machine. But I think not, something seems to be amiss - his scenario may be true if he was trying to push that endmill though the material - without it spinning (and therefore cutting.)



  7. #19
    Gold Member
    Join Date
    Apr 2009
    Location
    USA
    Posts
    5046
    Downloads
    0
    Uploads
    0

    Default Re: HELP! 5-Axis 4'x4'x30" CNC Router

    Quote Originally Posted by wizard View Post
    In any event to clarify communications here, im going to refer to the acises as X, Y, Z from bottom to top. (It is a pet peeve to be sure)
    A pet peeve of mine is the use of the plural of axis - which is axes (pronounced ax - sieze)

    As for nomenclature of the naming of each axis, I default to the standard Cartesian naming used since antiquity - X referring to left and right, from the viewpoint of the operator, Y going away and toward, and Z going up and down. End of controversy!



  8. #20
    Registered
    Join Date
    Dec 2003
    Location
    East Anglia,England
    Posts
    67
    Downloads
    0
    Uploads
    0

    Default Re: HELP! 5-Axis 4'x4'x30" CNC Router

    I will join the chorus saying that the "design" won't work for the required tolerances.I don't even think it can be built to move with the desired accuracy without any cutting force applied to the business end.You also need to take into account that thermal expansion alone can move your cutter tip more than 0.003" from the fifth axis pivot axis.If you have the work lined up I suggest going to see your bank to see if they can finance a decent machine from Correa or Jomech-a million dollars should do it.A decent CAM package will be quite pricey and you may need to hand over another stack of cash for a custom post-processor and there may be training costs associated with machine and software.

    If you really are determined to build a machine,and it is a great credit to the creative ability of a successful constructor,please consider the way in which you will demonstrate the success of the following alignment requirements:

    1.Having the Z axis totally perpendicular to the table at all times.
    2.Mounting the spindle so that it's axis coincides precisely with the fourth and fifth axes.
    3.Calibrating the home positions of the fourth and fifth axes
    4.Determining the distance from the fifth axis pivot point to the tool tip (you will need to input this value in the post-processor)


    Good luck with the machine,but I feel a lot of work needs to be done before any metal is cut.



  9. #21
    Gold Member
    Join Date
    Apr 2009
    Location
    USA
    Posts
    5046
    Downloads
    0
    Uploads
    0

    Default

    Quote Originally Posted by routalot View Post
    I will join the chorus saying that the "design" won't work for the required tolerances.I don't even think it can be built to move with the desired accuracy without any cutting force applied to the business end.You also need to take into account that thermal expansion alone can move your cutter tip more than 0.003" from the fifth axis pivot axis.If you have the work lined up I suggest going to see your bank to see if they can finance a decent machine from Correa or Jomech-a million dollars should do it.A decent CAM package will be quite pricey and you may need to hand over another stack of cash for a custom post-processor and there may be training costs associated with machine and software.

    If you really are determined to build a machine,and it is a great credit to the creative ability of a successful constructor,please consider the way in which you will demonstrate the success of the following alignment requirements:

    1.Having the Z axis totally perpendicular to the table at all times.
    2.Mounting the spindle so that it's axis coincides precisely with the fourth and fifth axes.
    3.Calibrating the home positions of the fourth and fifth axes
    4.Determining the distance from the fifth axis pivot point to the tool tip (you will need to input this value in the post-processor)


    Good luck with the machine,but I feel a lot of work needs to be done before any metal is cut.
    3) The Doughty Drive B/C head has homing sensors in both axes.



  10. #22
    Registered
    Join Date
    Dec 2003
    Location
    East Anglia,England
    Posts
    67
    Downloads
    0
    Uploads
    0

    Default Re: HELP! 5-Axis 4'x4'x30" CNC Router

    Quote Originally Posted by louieatienza View Post
    3) The Doughty Drive B/C head has homing sensors in both axes.
    Thanks for the clarification.Its good to know that the sensors are there,but I return to my point about calibrating them so that the installed spindle is known to be perfectly aligned when the machine is homed.It would also require that the mounting for the B/C head is offset with perfect accuracy so that the spindle is concentric with the C axis and parallel to the table.I don't think the task is impossible,but given the required accuracy it won't be easy.By way of illustration;a few years ago I had a boss who quoted for a job that had a 0.002" tolerance because he saw that the axis readout on the router went to three decimal places.I told him that I knew a fellow that owned a Yugo which had numbers all the way to 130 on the speedometer-didn't guarantee that it would actually do it though.



  11. #23
    Registered
    Join Date
    May 2017
    Location
    United States
    Posts
    5
    Downloads
    0
    Uploads
    0

    Default Re: HELP! 5-Axis 4'x4'x30" CNC Router

    Louie, Wizard, Jim, Andrew, and ger21, routalot:

    Thank you for your responses and insight. I appreciate you all backing me on the disparaging comment made off the bat by one of the users. I stated right away that this was a preliminary design, and was in no way final or even feasible. We are interns, tasked with a seemingly impossible task, and are young and inexperienced with respect to this industry. Your comments and wisdom drawn from experience have proven to be useful, and we are rethinking our approach. First off, I think that we are scrapping the idea of cutting aluminum for sure, and potentially scrapping the thought of cutting wood also. We are looking away from Mach 3, as suggested. We are rethinking the feasibility of 30" Z-travel, and looking more towards 12-15". The gantry has since been redesigned, as well as the z-axis assembly. More supports have been added to the frames.

    More design iterations to be had, and more updates to come. Again, any further insight is welcome and appreciated.



  12. #24
    Registered
    Join Date
    Apr 2005
    Location
    Canada
    Posts
    408
    Downloads
    0
    Uploads
    0

    Default Re: HELP! 5-Axis 4'x4'x30" CNC Router

    Since you are starting with a doughty drive most of your design choices are pretty limited. Essentially you want to build a regular router table, perhaps more rigid than usual to help offset some of the B/C axis slop and weight.

    On the surface it is a fairly straightforward project but there are some intricacies to how all the pieces get mounted (bearing preload/linear rail reference surfaces).

    As you design make sure you consider exactly how you will ensure everything is parallel/perpendicular. You need room to make adjustments as well as a practical way to measure alignments during assembly.

    There are several approaches you can take for producing flat surfaces and the best option depends on what tools are available to you. A weldment might be appropriate if you have access to a very large and precise machine that can square off the important surfaces. You might want to bolt together aluminum extrusion if you have access to flat surface for alignment. In the worst case, you can pour self-leveling epoxy on top of a steel frame and achieve flatness with the help of gravity.

    Finally keep in mind that rigidity and alignment are limited by the weakest link. You see a lot of hobby machines that look heavy but have one bad interface that wastes the machines potential.



Page 2 of 3 FirstFirst 123 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

HELP! 5-Axis 4'x4'x30" CNC Router
HELP! 5-Axis 4'x4'x30" CNC Router