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Thread: Changing X-axis envelope during machining, automatically. For machining long planks

  1. #13
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    Default Re: Changing X-axis envelope during machining, automatically. For machining long plan

    Quote Originally Posted by Storken View Post
    I think pneumatic will give me the force needed to start. As for setup and a possible dual vise setup - I'll just have to try and check the performance. What clamping force would be advisable to shoot for? will 100 kg be sufficient

    Happy new year!
    Have a Great new year also

    Nothing new about a saw using a dual vice method to move the work, which would work well for your machine

    100Kg would be a good starting point, 240lbs spread over 12" gripping surface would give you plenty of grip to index the work piece and index the wood sheet forward, this gripper vice having a Ballscrew and a servo motor would make the move very accurate

    There are many large Routers that already do a similar operation as to what you want to do that load and feed the sheets into the machine https://www.youtube.com/watch?time_c...&v=eqeiqpBDO5I

    Some simple Toggle Clamps you could experiment with to try out how much force you need, to clamp the work

    Attached Thumbnails Attached Thumbnails Changing X-axis envelope during machining, automatically. For machining long planks-toggle-type-clamps-png   Changing X-axis envelope during machining, automatically. For machining long planks-toggle-type-clampe-1-png  
    Mactec54


  2. #14
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    Default Re: Changing X-axis envelope during machining, automatically. For machining long plan

    Quote Originally Posted by Storken View Post
    Thanks for the tip about CamBam. For others checking in: It is free for use up to 1000 lines, with a licence running about 100 euros. Furthermore it can be expanded on with scripts.

    My summary is like this:

    Method_a: Engraving toolpath
    Pros: Easy to start with, will steadily climb in X-Axis
    Cons: Slow, poor surface finish

    Method_b: Common toolpaths
    Pros: Fast and good surface finish
    Cons: Not readily suited for my idea

    Method_a will work out of the box with a modifier, method_b will not.
    It would make life a bit easier to explain what you are trying to do with this construction lumber.
    The preferred case is a script that will split the model into smaller models that will fit inside the work area.
    Example: Part length 60 cm. Non-recurring features. 25 cm X axis travel.
    Part is split into part_a, part_b and part_c.
    Separate g-code is generated for part_a - part_c
    A script makes a new master g-code file where the structure is: part_a, move X-axis, part_b, move X-axis, part_c.
    If the repeated features don’t require precise registration with the previous run this can be very doable.
    I need to learn more about the possibillities within CamBam, and this should be able to work.



    Yeah, feed rollers are a interesting option. I haven't talked about spindle power and cutting forces yet, but I plan to use a 3-5 kW spindle once the motion control is mature enough (My day job is in ebikes and emotorcycles, so I have access to relatively high power low weight motors).
    I’d just buy a purpose made spindle.
    Routing is fun, but routing with high power is so much more satisfying. I believe feed rollers and high cutting forces are a no-go. Not too keen on making a pneumatic clamp, but more so than feed rollers.
    You Will need some sort of clamping System be it hydraulic, pneumatic or something else.

    Thank you for the long and interesting post. Some of your questions reveal more of my motivations. CNC Lathe Bar pullers was part of my inspiration actually!

    Why not build a long CNC? I do not have the room for it. This machine will be small, probably about 20-40 kg and therefore mobile (which opens up cool possibillities aswell).
    You can’t even serious with that weight value. This especially on a machine that you want to automatically handle 2x4 and 2x6 planks. Beyond nd that if the machine is used in an OSHA regulated environment you will need guarding on the entry and exit sides of the machine. To put it simply you end up needing more room than is required for a moving gantry machine long enough to handle the board lengths you will be processing.
    I definitely see the problems with construction timber and accuracy. Step 1 is to select good material. Step 2 is to realize that this machine will be precise, but not accurate.

    Use, down the line, include cutting steel. This is a whole different game than wood. The accuracy can be expected to be better than wood, but then again I expect steel parts to be finished to a higher accuracy than wood. (Magnetics can also be used for manipulating the work)
    I really believe you are in some sort of fantasy land here, I can’t even believe magine getting useful work out of a 20 kg machine in steel. I’m thinking several hundred pounds just for a machine suitable for wood. That doesn’t even include a hydraulics pack.
    You mention some g-code interpreting solution already have the needed features for a moving gantry designs. My Google-fu did not find any relevant resources (just a lot of common gantry design discussion). Can you point me to some resources?
    LinucCNC has a whole PLC subsystem. Others can be programmed to wait on an external devices. GRBL is fairly easy to understand and on a platform with enough I/O could be modified to support additional I/O functionality. The alternative that exists for systems using G-Code senders is to hack the G-Code sender itself to handle walking beam movements. There are many options here including using existing M codes and such.

    Which way you go depends upon many factors. LinuxCNC’s PLC support is very traditional as far as industrial automation goes. Hacking GRl might not be for everybody but programmers familiar with compilers might feel comfotable. Finally working on a computer that is doing the G-afore sending gives you unlimited power and flexibility. You are not really limited to these approaches either, rather there are hundreds of possible approaches.



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    Default Re: Changing X-axis envelope during machining, automatically. For machining long plan

    Quote Originally Posted by Storken View Post
    Found the Tormach new band saw.
    These sorts of systems are fairly common, probably for a 100 years now.

    I think pneumatics will give me the force needed to start. As for setup and a possible dual vise setup - I'll just have to try and check the performance. What clamping force would be advisable to shoot for? will 100 kg be sufficient for a first try?
    Again it design ends upon what you want to achieve.

    Consider this, to an extent you can flatten a twisted or warpped piece of lumber in these jaws. In fact you will have totally some extent just to get a reliable hold on the stick. How much force you will need depends upon how the wood is oriented in the vise, and the distance between vises.

    So if we make an assumption of a 2” diameter piston at shop air pressure of 90 psi that will be 280 pounds of force. In my opinion is that soil not be enough for clamping. At least not if you want to overcome modest twist. Even if it was enough you would likely want air regulators on the clamp cylinders so that they could be adjusted to the minimal clamping force required. The minimal clamping forces to reduce damage to the wood.


    You are probably correct in those assumptions. For reference the 5kW motor is 7 kg, but motorcontroller (2 kg), spindle (xx kg) and accessory hardware will quickly add up. The motion control would need to match the spindle to load it sufficiently, and the rigidity of the machine would also need to be suitable.
    Just the walking beam clamping assembly will be pretty heavy. You have two requirements’ it needs to not bend when clamping. The second need is to not twist or bind when walking heavy stuff.


    Yes, I agree. I'd rather someone set me straight now, than several months down the line.

    Then again, CNC is continually developing and while this machine will not make sense in a professional environment - it can be a fun addition to a hackerspace or hobby-shop arsenal.
    It is one thing to set up something like this in a private shop. It is something totally different to have automation running in a place with public availability. I don’t mean to be a party pooper here but people get caught up in conveyors and similar mecanis s all the time.

    If you want to build something for a hackers space delete the walking beam frame m themachine. Because frankly if it isn’t guarded somebody will get caught up on n the machine. I know this for a fact because I’ve worked with the safety department to resolve numerous safety problems and a lot of them have todo with these sorts of things. You have the option of guarding but that increases machine size. You often end up asking your self how did they manage todo something so stupid yet the injuries happen.


    Thank you for sharing your experience. This is meant to be a project to do complex stuff with simple means. I'm not quitting my day job or ordering a robot arm. This project might take 3 months, it might take 2 years - we'll see.

    Happy new year!
    The important thing is to have some fun with it. By the way, it is a bit late but happy New Year.



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Changing X-axis envelope during machining, automatically. For machining long planks

Changing X-axis envelope during machining, automatically. For machining long planks