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  1. #11
    Hi,

    First Kyle's got it all wrong I'm no master.. . . . But I have offerd advice with design thou struggling with finding time at the minute.!!

    The machine(2 actually) I'm building which you referred to has high sides because the bed is adjustable. It will easily handle aluminium with bed set to it's higher settings keeping the Z axis extension short.
    The adjustable bed as a few bennifits.!! It allows larger deeper material and/or the use of vices or 4th Axis plus allows flexabilty in material choice upto aluminium and even very light steel use with a decent spindle and correct cutters.
    The high sides means the gantry sits direct onto the bearings giving maximum strength, no flexing flappy gantry sides.

    These machines are a smaller version and losely based on my machine.They basicly incorparate improvements and lesson's learnt with my machine. They are an allround machine and very versatile which will do most jobs very very good. . . . BUT . . . If you want to just exclusively cut aluminium then I'd recommend you take a slight different route.

    My machine almost exclusively cuts aluminium and without any trouble but if starting again to EXCLUSIVELY cut ALuminium then I'd drop the adjustable bed to gain Max frame strength, beef up the gantry and the Z axis and incorparate full flood cooling. . . . PLUS . . . I'd mount it verticle.!!! (See my post of mine roughly proped against wall cutting 10mm single pass)
    While mine happily cuts at 1.5-2mm Depth of cut at 1000mm/min and will even rough upto 3mm(thou it moans a bit) just these few extra features will increase DOC and feeds plus increase finish quality.
    My next machine will have all this plus an added unusual extra MAX Strength gantry/Z axis design which you'll just have to wait to see.!!

    Regards good and bad PSU that depends.??
    It's very important the PSU is sized correctly to the motors being used, unregulated supplys suit steppers better than regulated linear supply's and are the prefered choice because they handle the back EMF steppers produce when deaccelerating better.
    Often it's cheaper and better to build a toroidal supply, doing this means you can size the voltage and amps pritty much exact to your motors ideal requirements.
    It's a very common mistake for folks to buy the wrong size supply because they are confined to standard sizes available, often they buy too low voltage which is a big mistake. Steppers get there speed from voltage so it's extemely important to get this correct so in this regard yes there is good and bad.!!

    I'll say to you what I say to everybody.!! Don't buy a thing untill you have fully settled on the design and know the materials and have an idea of weight's etc to be moved around. With 1000 budget you can't afford to buy a single thing wrong but it is just about do able.

    Just ask if I can help and I'll try.

  2. I would strongly follow that advice that Jazz is giving and don't forget to design space for the limit and home switches. Trust me on that one.

    Michael

  3. #13
    I stand by my first statement Jazz is a master, extremely knowledgable, and one of the most helpful people I have meet on a forum EVER!

    As Marino said stick very closely to Jazz's advice and you won't go wrong!

    (Looks for bowing down smiley)

  4. #14
    Quote Originally Posted by m.marino View Post
    don't forget to design space for the limit and home switches. Trust me on that one.

    Michael
    And that really was said with feeling:lol:

    bruce
    The more I know, I know, I know the less. (John Owen)

  5. #15
    Hi Guys,

    Thanks for ALL the advice, after the whole weekend doing some research and messing with the designs and Ideas I have come to the point where I would like to know what hardware Sizes I should be going for.

    I am looking at a design with a raised X-Axis, similar to JazzCNC design mentions earlier.

    To complete my design work I need to know some things, only a few questions I promise!:whistling:

    From my understanding Linear Profile Rails are the way to go as they are the "Most Stable/Accurate" option. What size would be best for the X-Axis and Y-Axis? Should I use them for the Z-Axis? Also how many bearing blocks per Axis? Is there a calculation to work it out?

    Now onto the Subject of Ballscrews, again from research the "Most Stable/Accurate" option would be to have a Stepper running a Ballscrew on each side of the X-Axis, is this correct? Again, What Size ballscrew for each axis? Is there a Calculation to work it out?

    @JAZZCNC: Some very good Advice, kept me busy for the weekend. Regarding the Budget, you are correct, I would rather Plan and Plan and not waste money as the budget is tight. When you say beef up the Y-Axis, could you elaborate a little?

    @m.marino: Yes, some very Good Advice from JAZZCNC, regarding the Switches, I have added them to my notes as a Priority!

    @kylelnsn: Yeah, JAZZCNC sure looks like he knows his stuff, not sure about all this Vertical talk though!

    @motoxy: LOL! :lol::lol::lol:

    Again, thanks all for your Help, Time and Patience!

  6. #16
    Quote Originally Posted by JunkieHobbo View Post

    From my understanding Linear Profile Rails are the way to go as they are the "Most Stable/Accurate" option. What size would be best for the X-Axis and Y-Axis? Should I use them for the Z-Axis? Also how many bearing blocks per Axis? Is there a calculation to work it out?
    15mm Profiled rail will be sufficient with 2 bearings per rail. Regards calculations etc you could do them but profiled rail & bearings, even 15mm bearings, are designed to hold a huge amount of weight far more than your's or most DIY machines will ever need so I wouldn't concern your self too much in this department.

    With profiled rail there's different types of carriage, usually 2 lengths standard and long, then there's slim and wide type carriages.
    Think of the bearings as a foot print the wider and longer the more planted the foot, if using 2 ballscrews to move the gantry the length can be reduced slightly because of it being driven and held both sides but longer and wider is better than fine n slim, trade off being extra length rails needed for same cutting area.

    Use them on all Axis but with the Z axis mount the rails on the front plate and bearings on the rear plate, this will give the maximum strength when the Z axis is extended.

    Quote Originally Posted by JunkieHobbo View Post
    Now onto the Subject of Ballscrews, again from research the "Most Stable/Accurate" option would be to have a Stepper running a Ballscrew on each side of the X-Axis, is this correct? Again, What Size ballscrew for each axis? Is there a Calculation to work it out?
    Yes driving the gantry with 2 ballscrews is much stronger than using a single screw because it reduces the racking or skewing affect when cutting at the outer edge's of the machine, more so the wider the machine.
    Regards size etc then you have a few options.!! It's not rocket science but does revolve slightly round the type of use of the machine and the length.
    Basicly you choose the screw by pitch and diameter and length.
    If it's going to be used as a general purpose machine IE, wood, plastic's, soft metals then a good all round pitch is 10mm. This will give a good balance of speed and resolution.
    If it's to be used for very detailed work Ie: Engraving etc then you will want a lower pitch like 5mm or less, the advantage being higher resolutuon. The trade off being slower rapid and cutting feeds.

    The diameter is often determined by length and what's pitch is available in that diameter. Long screws 1300mm and above need to be thicker to handle the whipping affect unless some other method is used like rotataing the ballnut and keeping the screw fixed in tension at both ends.!
    Again there's a trade off.!! . . Larger ballscrews weigh more and therefore take more energy/force to be accelerated they also produce more inertia which as to be de-accellerated the net affect is this requires larger motors which require larger drivers which require larger PSU's all this add's to the expense.

    Depending where you buy the screws(Probably from china for cost reasons.!!) you'll find 10mm pitch is often only available in 16mm or 25mm dia for some reason.?? 20mm is nearly always 5mm pitch.?
    For an all round machine Upto 1200-1300mm then 16mm Dia meter with 10mm pitch is a good choice.

    For higher resolution but with less speed then 5mm pitch is a good choice, would will also be ok regards whipping upto around 1500-1600mm with 20mm due to less rotational speeds. (my machine use's 150mm 5mmpitch 20mm Dia with no whipp upto 12meter/min)

    Another option and something I like and know Jonathan likes to use is connecting the motors to the screws via a short timing belt.
    Doing this gives a few advantages.! . . It reduces resonance which direct drive can suffer from and it also allows for easy gearing to either increase speed or resolution/torque. Makes a machine that bit more versatile.

    Quote Originally Posted by JunkieHobbo View Post
    When you say beef up the Y-Axis, could you elaborate a little?
    Yes very simple really.! When cutting metals, even soft metals like Ali or brass the machine needs to be very very strong if you want to have any kind of resonable depth of cut (DOC) and feed rate(FR) with a nice finish.
    To be honest most half decent built machines can cut Ali or brass. . BUT . . There's cutting and there's cutting.!!
    Lighter less ridged machines will have to take far less DOC and often go slower, thou less DOC does mean you can go faster on the FR but the machine becomes the restriction. Less ridged machines suffer from resonance which transfers to the finshed cut quality, the faster FR or deeper DOC the worse the finish due to resonance.

    Basicly if you want to soley cut metals then build it strong and heavy in all departments, don't be affraid of weight, the Mass helps massively with quality of cutt.
    Again the down side is more power and bigger components required to handle the weight etc. Plus an often over looked but again massively important area is the Z axis and Spindle used.??
    No point building a strong framed machine with the best components etc if the Z axis is under built and flexing around or there's a weedy spindle attached that can't handle the DOC or FR.
    If you want a decent machine just for Metal be prepared to build strong and spend money. . .OR . . . Some times easier/better to Convert a milling machine.


    Quote Originally Posted by JunkieHobbo View Post
    @kylelnsn: not sure about all this Vertical talk though!
    Why would you say that.!! . . . When you have used a machine for a while you'll inderstand better and defiantly see/appreciate all the advantages.!
    With a few weeks experience using it in the vertical position I can absolutly say 110% it's the best thing I've done to the machine since I first built it, and with the excepton of slightly more awkward clamping which I've fully adjusted to know i've made some little rest aids there's absolutly NO down side only big positives.
    I would recommend anybody building from scratch to think long and hard and not be put off by the unusual positioning.!!. . . There are virtualy no down sides only positives..:dance:

  7. #17
    @JAZZCNC: Thanks for the Great information and your time for posting.

    I have started working on the Steel base Structure, I have the overall size but height will be adjusted/tweaked as soon as I get the machine completely drawn up.

    Here is what I have so far, I am using 100mmx50mm Steel Box with 3mm wall, I am sure this will be more than strong enough.
    Click image for larger version. 

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    Is there anything the looks glaringly/obviously wrong?

    I will continue to work on the Design and keep everyone posted.

    Use them on all Axis but with the Z axis mount the rails on the front plate and bearings on the rear plate, this will give the maximum strength when the Z axis is extended.
    I am not quiet following you here, could you show me an example of what you are talking about?

    Another option and something I like and know Jonathan likes to use is connecting the motors to the screws via a short timing belt.
    Does anyone have any pics of a similar setup?

    On another note regarding the Stepper/Ballscrew on both sides of the X-Axis, what happens when 1 stepper falls behind or fails?

  8. #18
    Quote Originally Posted by JAZZCNC View Post
    Why would you say that.!! . . . When you have used a machine for a while you'll inderstand better and defiantly see/appreciate all the advantages.!
    With a few weeks experience using it in the vertical position I can absolutly say 110% it's the best thing I've done to the machine since I first built it, and with the excepton of slightly more awkward clamping which I've fully adjusted to know i've made some little rest aids there's absolutly NO down side only big positives.
    I would recommend anybody building from scratch to think long and hard and not be put off by the unusual positioning.!!. . . There are virtualy no down sides only positives..:dance:
    I didn't say that? Lol? Confused!

  9. #19
    Hi,

    Please don't think I'm picking fault with what I'm about to say it's just my opinions mixed with experience.!

    I'm currently building the machines that I think you've seen and based this design from. My frame is using 80x40x3mm and 40x40x3 I can tell you it's more than enough and very heavy so I would recommend you save a bit of money and go with 80x40 it will more than do what you want.

    Regards the frame layout I would change several things and add a few.! It's easier to show than explain so I've drawn a quick model to show it. Doing it like this gives more weld area and better stiffer bracing.
    One thing I suggest you do is NOT weld the top piece which the rails sit on to the upright legs.? Better if you weld flat plates to the uprights and then bolt the top piece. This gives better control of getting the two sides parallel, basicly you can shim and adjust them into parallel planes.

    RE Z axis. See pic with front plate missing (and only1 rail) this use's profiled linear rails but the principle is the same supported round rail.
    As you can see the bearings bolt onto the rear plate that travels along the Y axis and the rails bolt onto the Z axis front plate which the spindle attachs too. The reason for doing it this way is to gain from the fact the flex of the front plate become less or more as the extension increases or decreases. Doing it the other way round the extension of the rail from the bearing is always the same distance whether extended fully in or out and with long Z axis this becomes a spring board at any z extension.!!

    RE Timing belt. See updated model of current machine. The following will also answer your concern regards steppers falling behind
    To be honest if your going to have a piece across the back like the model suggest's then I would urge you to connect the two ballscrews together with one timing belt and use just one motor to drive both. This address's several issue's and saves you some money, my own machine use's this setup so I can tell you 100% it works and works very very good so don't be put off with the use of timing belts. . . .Here's why.!!

    First and foremost it completly eliminates any sync problems(falling behind) with the 2 screws and takes away any fear of racking or damage from one motor stalling and the other continuing which belive me when it happens, esp at high speeds, can do lots of damage. This is the main reason why I prefer this method.!
    It allows higher rapid feed rates because you don't have to affectively de-tune your motors to be sure your in a safe non stalling tuning range like you have to do with slaved motors.
    Because it use's belts it's easy to change ratio's for extra speed or torque/resolution, basicly depending if you gear up or down and the ratio you change one pulley for another and you have either doubled, tripled your speed or resolution/torque.
    You only need one drive and motor to drive 2 screws which save a bit of money, thou you dohave the belts and pulleys to buy which lessons it a bit but your still in front and you save some input's and outputs on the parallel port.!!

    Like I say don't be put off with belts they work fine and in over 3 years I've only broke 1 belt and that was my fault for not tightening a pulley after messing. The accurecy and repeatabilty of my machine is fantastic and in no way suffers thru using belts and I mainly cut aluminum with it. Just see my Aztec calender too see that and if any issues then no way would it do work to this level of detail.

    Hope this helps.!
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  10. The Following User Says Thank You to JAZZCNC For This Useful Post:


  11. okay on X axis one or two ball screws? Also you might want to put a brace in half way down the X axis rail to help reduce any possible flex (depends on weight of gantry and such). Please remind me of dimensions as have been in the shop all day truing (tuning) the motors and travel. Therefore really not looking back in the thread for the info' (yes I am that mentally tired). Other then that looks like a good solid start.

    Michael

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