Thread: BuildingAfloat

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  1. Hi All,

    Was wondering if anyone has seen my last post, been up for 4 days now. I'd like to know if I'm going in the right direction before spending any more time on the drawing?

    Cheers,
    Geoff.

  2. #62
    Quote Originally Posted by BikerAfloat View Post
    Hi All,

    After some more reading and some hard thinking, here is the Mk2 machine (progress so far):

    Attachment 6608

    Went back to the drawing board completly, re-assessed the space and scaled the machine to what I think I can get away with, rather than basing the machine on the A3ish size previously.

    Ive used 5mm Wall Steel RHS as that should be good for the tapped threads to hold down the rails.

    Bottom Cross members: 120x60x870
    X Rail Supports: 120x80x900 with 900mm SBR25 Supported Rails
    Ballscrew Supports: 80x40x220
    RM1605 Ballscrews on all Axissss.
    Gantry "Feet": 80x40x200 5mm Wall Steel RHS with 2 x SBR25 Bearing Blocks
    Gantry Cross Member: 80x80x870 with 2 x 700mm SBR25 Supported Rails, top and bottom.
    Y Axis Ballscrew Supports: 10mm Thick Steel plate
    Z Axis Plates: 12mm Thick Steel plate
    Z Axis Rails: SBR25 Support rails 300mm long

    That makes travel roughly X=780, Y=480, Z=100

    Y & Z are driven by 2:1 Belt drives, for the X Axis, I am considering a single belt, 3 pulleys and 2 idler bearings also at 2:1 reduction

    That's a 2.2kW watercooled spindle on the Z, though I'm also looking at the Treadmill motor option for low rpms. Just waiting for a suitable treadmill motor to appear on eBay!

    Problem with this machine is I'll have to "borrow" a mates workshop to build the frame and pay someone to make some of the other components as they go beyond my skills and equipment, ho hum, not the original plan, but I'd like to build just 1 machine and have it last me.

    As you can (probably) see in the image, the Spindle comes outside the X Axis, I have left this as it gives me good travel over the steel box which I plan to use for a base for machining metals.

    Most likely welded construction, though bolts still hold some appeal for maintaining a "I built it myself" perspective...

    ... Just noticed I will have to bolt on the Y axis leadscrew/motor mounts, otherwise I can't get the leadscrew in!

    looks ace to me, although i wouldn't know if you'd done anything wrong.. although i cant see your Y axis ballscrew in the picture

  3. Quote Originally Posted by wilfy View Post
    looks ace to me, although i wouldn't know if you'd done anything wrong.. although i cant see your Y axis ballscrew in the picture
    Hi Wilfy, thanks for that, there is no leadscrew on the Y Axis yet, drawing very much waiting for input before I do any more!

    Cheers,
    Geoff.

  4. #64
    I notice you've opted for steel plate on the Y and Z axis. The vast majority of people use aluminium instead of steel since it is so much easier to machine, particularly with limited/basic tools. 20mm is a good size for the Z-axis.

    You could make the top Y-axis rail longer (820mm ish?) and increase the spacing of the two SBR25 bearings upon it, so the plate the Z-axis bearings are mounted on would be a T-shape. Although not critical since your Z-axis is already a good size, this would increase the rigidity for little extra cost.

    What's the plan for the bed?

    Quote Originally Posted by BikerAfloat View Post
    Hi All,

    After some more reading and some hard thinking, here is the Mk2 machine (progress so far):

    Attachment 6608

    Went back to the drawing board completly, re-assessed the space and scaled the machine to what I think I can get away with, rather than basing the machine on the A3ish size previously.

    Ive used 5mm Wall Steel RHS as that should be good for the tapped threads to hold down the rails.

    Bottom Cross members: 120x60x870
    X Rail Supports: 120x80x900 with 900mm SBR25 Supported Rails
    Ballscrew Supports: 80x40x220
    RM1605 Ballscrews on all Axissss.
    Gantry "Feet": 80x40x200 5mm Wall Steel RHS with 2 x SBR25 Bearing Blocks
    Gantry Cross Member: 80x80x870 with 2 x 700mm SBR25 Supported Rails, top and bottom.
    Y Axis Ballscrew Supports: 10mm Thick Steel plate
    Z Axis Plates: 12mm Thick Steel plate
    Z Axis Rails: SBR25 Support rails 300mm long

    That makes travel roughly X=780, Y=480, Z=100

    Y & Z are driven by 2:1 Belt drives, for the X Axis, I am considering a single belt, 3 pulleys and 2 idler bearings also at 2:1 reduction

    That's a 2.2kW watercooled spindle on the Z, though I'm also looking at the Treadmill motor option for low rpms. Just waiting for a suitable treadmill motor to appear on eBay!

    Problem with this machine is I'll have to "borrow" a mates workshop to build the frame and pay someone to make some of the other components as they go beyond my skills and equipment, ho hum, not the original plan, but I'd like to build just 1 machine and have it last me.

    As you can (probably) see in the image, the Spindle comes outside the X Axis, I have left this as it gives me good travel over the steel box which I plan to use for a base for machining metals.

    Most likely welded construction, though bolts still hold some appeal for maintaining a "I built it myself" perspective...

    ... Just noticed I will have to bolt on the Y axis leadscrew/motor mounts, otherwise I can't get the leadscrew in!
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  5. Hi Jonathan and thank you for your post,

    Quote Originally Posted by Jonathan View Post
    I notice you've opted for steel plate on the Y and Z axis. The vast majority of people use aluminium instead of steel since it is so much easier to machine, particularly with limited/basic tools. 20mm is a good size for the Z-axis.
    Opted for 12mm steel for strength and to keep the overhang low-ish (well low within the restrictions of supported rails), I thought I'd keep the aluminium down to a minimum for stiffness. I'll see what the 20mm gains me in reduced overhang, it might be worth a drop in stiffness over 25mm. What size do people tend to go for?

    Quote Originally Posted by Jonathan View Post
    You could make the top Y-axis rail longer (820mm ish?) and increase the spacing of the two SBR25 bearings upon it, so the plate the Z-axis bearings are mounted on would be a T-shape. Although not critical since your Z-axis is already a good size, this would increase the rigidity for little extra cost.
    I had considered that, may look at the drawing again, I have to mount limit switches yet and thought the space could take the mountings for them, that was all.

    What's the plan for the bed?[/QUOTE]

    I am leaving that open in this sketch, but I have plans for several options:

    1) A simple MDF bed with 2 layers, support and spoilboard
    2) Aluminium (or maybe even steel) drilled and tapped
    3) Open to allow a 4th axis to be mounted
    4) A removable T Slotted Steel bed across the front cross member
    5) Open to allow me to mount motorcycle engine casings on the bench beneath for engraving

    Basically I have left it free to see what develops over time.

    I'm hoping with the small overall size and the relatively large size of the frame in comparison, it should be up to most of what I can see me throwing at it... Only time will tell.

    Cheers,
    Geoff.

  6. #66
    Quote Originally Posted by BikerAfloat View Post
    Opted for 12mm steel for strength ... I thought I'd keep the aluminium down to a minimum for stiffness.
    20mm thick aluminium would be just as strong. You will save the difference in price between aluminium and steel from the relative machining difficulty.

    Quote Originally Posted by BikerAfloat View Post
    I'll see what the 20mm gains me in reduced overhang, it might be worth a drop in stiffness over 25mm. What size do people tend to go for?
    I think we're talking on cross purposes - I was referring solely to steel plate, not the rails. However since you've mentioned it - the 25mm rails are much better than 20mm since in addition to being a bit stronger due to the size they also have one more row of ball bearings in the blocks.



    Quote Originally Posted by BikerAfloat View Post
    I had considered that, may look at the drawing again, I have to mount limit switches yet and thought the space could take the mountings for them, that was all.
    Having the machine as strong as you can is far more important than having a convenient place for a limit switch. You'll find somewhere to put them.

    Quote Originally Posted by BikerAfloat View Post
    1) A simple MDF bed with 2 layers, support and spoilboard
    2) Aluminium (or maybe even steel) drilled and tapped
    3) Open to allow a 4th axis to be mounted
    4) A removable T Slotted Steel bed across the front cross member
    5) Open to allow me to mount motorcycle engine casings on the bench beneath for engraving
    Although clearly 1) is the weakest it's not a bad idea to use MDF to start with as it will be adequate for most things, makes clamping easier and doesn't kill the tool if you make a mistake.

    Quote Originally Posted by Ricardoco View Post
    take a look and see if you can spot the mistakes..lol

    [...]

    Thats better..
    Your dimensioning still doesn't add up. Mine is definitely different to that drawing - size, aluminium piece on front is a different shape, smaller connector.

    There's also now 4 bearing spindles readily available - these are 215mm long instead of 200mm.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  7. Hi Jonathan,

    Thanks for your post,

    "I think we're talking on cross purposes..." - Yup my mistook!

    I'm going to have to borrow a mates workshop for this build, so I'll be able to work the steel plate almost as easily as the Ally there, so from a rigidity and space point of view I'm plan to stick with Steel plate.

    I wasn't aware of the extra row of bearings in the 25mm bearing blocks, that's a good reason to stick with them, the space saving is only 10mm if I went to 20mm rails on the Z Axis anyway.

    Cheers,
    Geoff.

  8. Hi All,

    Here are the latest drawings for the machine, it's nearly there, just need some advice on the X Axis belt drive, or more specifically the idler pulleys, I can work something out, but I'd rather go with a tried and tested system. They are currently set at 25mm OD, their construction and size are open to change.

    Click image for larger version. 

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    I know steel rings like a very ringy thing and some form of filling is in order, I'm pretty sure I wont be able to use epoxy and agregate from a weight point of view, I have to consider the stability and balasting of the boat. I was wondering if expanded foam would act as a dampener, anyone got any experience/ideas?

    Spindle shown is Chinese W/C - 2.2kW one, I also plan to have a dedicated low speed job for the harder materials. My supply is currently (Sorry for the pun) limited to 16Amps on the landline - going to have to do some sums to see just what a compromise this will cause. 2200W @ 240v = 9.2 Amps so 6.8Amps left. This means I would have not a lot left for everything else (Fridge, Lighting, 2nd PC!) , Me thinks either a 2nd landline or more likely a generator will be required!

    I can pm the sketchup file if anyone would like to check it over, all I really need to know is that the design is buildable, I'm fairly sure it is, but sometimes you can miss little details when you are too close to something.

    I'd like to learn the capabilities and limitations of this machine design, I've taken a lot on board for this design from previous posts to this log and from reading other peoples experiences, but there has to be a time when you stick a stake in the ground and this is where I find myself. If you see something is dangerous or impossible please tell me so and I will change it. Otherwise this is the machine I plan to build warts and all.

    If the design is doable (Not perfect, but doable) I plan to start buying components sometime in the next week or two. The order I think I'm going to use is something like this:

    1) Linear Rails and Bearings - Need this to be sure of the holes I need in the steel.
    2) Steel.
    3) Pulleys and belts - to make sure of the sizes so I am safe for the Ballscrew Machining.
    4) Ballscrews and Bearings.
    5) Steppers.
    6) Electronics & controller software. 3 choices Planet CNC USB, EMC2 or Mach3(4?) Need to do a feature/cost comparison Gut says Planet CNC as I need a BOB and the software was written to work specifically with their BOB, Head says Mach3 as it seems to be the most used and the little perverted Demon on my shoulder says EMC2, as it's about time I learnt about Linux!
    7) Spindle - probably use my hand router to start cutting and pay for W/C jobby and the dedicated low speed one.
    8) Additional software for modelling - going to start with the free stuff to get the feel of the machine.

    Does this seem logical, are there changes I should make?

    Another long post, so I'll stop here and wait for a while before adding any more.

    Cheers,
    Geoff.
    Last edited by BikerAfloat; 17-09-2012 at 02:58 PM. Reason: Made stupid mistake about ER16 Collets, when ER20 is what I really need - Doh!

  9. #69
    sorry i can't add much again, but what i will say is consider emailing the dude your getting the rails and screws off first for a price and pay outside of ebay, this way you will get a better price and while your at it get him to quote you to include and also not include the spindle.. chances are due to combined postage and a big order you may find yourself getting the spindle alot cheaper than anywhere else.. this is certainly my play when the time comes.

    also i only just realised your building this machine to work on a boat.. thats just awesome in its own right.

    expanding foam is also something i was considering for my build.. it's very cheap and i think it would go some way to take the ring out of the steel as it wouldnt have any air to resonate through the center of the box section

  10. Quote Originally Posted by wilfy View Post
    sorry i can't add much again, but what i will say is consider emailing the dude your getting the rails and screws off first for a price and pay outside of ebay, this way you will get a better price and while your at it get him to quote you to include and also not include the spindle.. chances are due to combined postage and a big order you may find yourself getting the spindle alot cheaper than anywhere else.. this is certainly my play when the time comes.
    Good idea Wilfy, my strategey for ordering bits is based on me funding the job myself, so the spindle is my last purchase, however I am pursuing a couple of other avenues for funding - I am Bi-polar (Manic-Depressive) and it is difficult for me to be employed, hence building the machine to enable me to be self employed. The upside of my illness is the support from the Mental Health team. They beleive there may be some funds to help people like me back to work. If the funds come from there in a lump sum, then I will be looking at making them go as far as I can and that is a good strategy, Thank you for the idea.

    Quote Originally Posted by wilfy View Post
    also i only just realised your building this machine to work on a boat.. thats just awesome in its own right.
    Hee Hee, Home is a 53' Narrowboat, I'll be lossing quite a bit of living area to accomdate this, but if I can keep my costs down by not having to rent a workshop, the the plan for self-employment is that bit more viable.

    Quote Originally Posted by wilfy View Post
    expanding foam is also something i was considering for my build.. it's very cheap and i think it would go some way to take the ring out of the steel as it wouldnt have any air to resonate through the center of the box section
    Glad to hear I'm thinking along the same lines as someone else, makes it seem a more viable idea. Thanks again!

    Cheers,
    Geoff.

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