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  1. #277
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    Thank you John for your prompt reply
    I've just finished my first homemade cnc from aluminum, it was really a challenge to do it on my kitchen without mill and late
    So I was thinking about casting some parts from urethane, I think ill do it on my next project.
    And yes I have already found tool holders you've been using in your machines so I decided that my initial thoughts about casting such complicated parts was right and I can give it a try
    Thanks again
    Dmitry



  2. #278
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    You are very welcome Dmitry...

    With the experience you already have casting urethane, it should be
    easy for you.


    John



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    Well, here she is all painted up nicely...

    Still need to make the leadscrews and a few other little details

    Sure looks a lot different with the paint job.



    John

    Last edited by microcarve; 10-21-2010 at 04:48 PM.


  4. #280
    Gold Member Bubba's Avatar
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    Looking GOOD! I haven't near that far on mine yet!

    Art
    Country Bubba (Older Than Dirt)


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    Thanks Bubba!



    I was up allllll night doing the painting. Had to do it 3 times before I was
    satisfied...(enough).

    I'm not fond of painting because they always get a ding or two when getting
    them test-reassembled a few more times and that drives me nuts. So I'm
    content with selling them for less if someone is willing to do the painting
    themselves.

    I did manage to get this one pretty good looking though....

    John



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    The table looks a little small and that's intentional. It's meant to
    be used with more layers. Those layers can be offset front to back,
    or even extended for various bolt on fixtures/jigs.

    I made a few posts early on about using t-nuts and an easy way to
    put them in place....

    Also, the closer work can be brought to the bottom of the Z axis, the finer
    the work can be. Leverage. Short bits are most always better when they can
    be used.

    Lots of possibilities with quick-change bolt on MDF fixtures.


    John

    Also...that's just a temp table til I get the other done.....



  7. #283
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    Mannnn, I'm forever trying to get a good system down for painting.
    It changes all the time. So here's how this one went....

    I really wanted the big panels white. That's just begging for trouble --for me.

    As I mentioned earlier, during the constant assembling/re-assembling, I took
    time to brush on a mix of yellow wood glue and water several times throughout.
    That ended up with about 3 coats.....all dried between testing assembly.
    About 25% glue to 75% water.....not anything specific.

    That was a big help in the end. Looked like crap, but it did a nice job sealing
    in the end.

    Then I sprayed it all....(white parts)...with Zinsser BIN spray shellac. That
    stuff has good white solids in it and dries fast. Good stuff.

    A light sanding and then Krylon coats of white enamel. I have great luck with
    Krylon colors. Rustoleum doesn't dry fast enough for me. Maybe too humid
    where I live in South Georgia. But the Krylon worked really well with about 3 coats.

    The black is Krylon Ultra Flat Black. Possibly the best paint that ever existed,
    but I think they've actually discontinued it. I've used that paint for at least
    30 years and I'm amazed they'd quit making it. I'm buying it up for later
    on the internet as I have a little spare $$$.
    But it dries super fast and is *Flat Black*. No undercoat was needed with
    it for the black parts.

    So that's how the ever changing painting went on that one. So far no
    dings....but it's only a matter of time....

    John



  8. #284
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    I've had a few inquiries about my machines lately, so I'll
    go over a few points about them.....

    Whenever I myself choose some thing I want to buy, I can pretty
    much figure out for myself why I like it and whether it's what I need.
    I don't need or like any hype or misleading BS.

    That said, the thing I DO want to know is what may make me have
    regrets about my decision. I regularly make a point to point
    out any shortcomings of things I make and sell.

    I have no one else's machine to make a direct comparison with. My
    judgments on my machines performance are based on my own needs from
    them. I do make them as well as I can and with quality materials.
    The necessary time to do things correctly is spent.

    None of them are "perfect" and I doubt that's possible due mostly
    to my own increasing demands from them. They may be shipped unassembled
    and once reassembled some other place by someone else, they may need
    a slight adjustment or two. That normally is due to parts that are
    so closely fitted being inadvertently reversed and maybe a little tightness
    or binding is evident. Simply swapping one matching part with another
    fixes it in most cases.

    The design is such that it can mostly only go together one way, avoiding
    confusion, but there are "pairs" of parts involved.

    There is intentional friction in the machines. That's the only way to
    make them without any play at all in them. Make "play" impossible.

    There will be points along travel where there is a very slight
    noticeable tighter point. Not so tight that it matters, but glass smooth
    travel like linear bearings isn't likely. Even the Precision Thomson
    shafts aren't perfect. Simply twisting one can make a difference.
    The machines attempt the perfect travel and when the leadscrews are
    in place, it seems it does so. Screws are extremely powerful levers.
    They will overcome the very slight tight points in travel easily
    and effortlessly.

    The machines are designed for Nema 23 motors in the 150 to 300 oz range. The
    cost difference for the gain in performance is well worth the extra few
    $$ they cost.

    Nuts are sometimes a fraction on the tight side. Better to have no backlash
    and a tiny bit of friction than a sloppy fit. The recommended motors will
    work fine. The nuts can always be made looser, but it's tough to make them
    tighter.

    Parts are not generally interchangeable when they're individually made for
    a specific machine. The fitting is too close.

    Machines are like cars...or most anything mechanical, they may each have
    or develope their own quirk, but they're designed so anyone with any common
    tools can go to any hardware store worldwide and easily do any repair, upgrade,
    modifications, enhancements or general hacking any time needed or desired.
    Any "special" parts are lifetime parts. Z axis for example. They should never
    wear out.

    These are very inexpensive machines....for now...but should be fully expected
    to do full time work at what many may consider legitimate commercial use.
    They have been built hundreds of times using the same basic techniques for
    about 6 yers now. There are over 1000 machines using those techniques in use
    all over the world. Those machine were sent out in about 15 different
    variations.

    A few of those variations are what I consider rock solid designs. These are
    one one those few. There's very little that can go wrong with the purely
    basic design. Once adjusted, it'll last and work for the foreseeable future.

    There's not much to adjust. A few holes are a few thousandths large to allow for
    squaring and leveling. It'll go as level and square as someone is willing
    to take time to make it. But, it'll also work just fine with a general quick
    assembling. Likely rarely noticed that it could be even better.

    The machines are very high quality, but they're still not perfect. From the
    examples shown along the way in this thread, they're about as perfect performers
    as they can get.

    Again, I don't like being hyped to, and I wouldn't expect anyone else would
    either, so I'm very open to any and all questions anyone may have about the
    machines. Anyone considering such a machine should do lots of homework and
    comparisons before making any decisions about buying any machine from any
    place. Hard questions should be asked. CNC is not for everyone, nor is the
    the "push-n-go" solution many newcomers think it is. It requires a great deal
    of attention and work to have any chance of success with it.

    But, once they "get it".....cnc cannot be beat. It's one of the coolest things
    there are. It'll do things no other tool or machine can do.

    It's worth the effort....

    I make these personal observations to hopefully benefit newcomers to
    the hobby....and anyone interested in these particular machines.


    John



  9. #285
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    Hi John! Once again - Your machines are great!!!
    Its a pity that I did not found your tread earlier, before I started to built my aluminum one
    Please could you be so kind to make a picture of your machine from the bottom or without table installed, Its just interesting to see your X axis design(if it is not atop secret)

    Dmitry



  10. #286
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    Ahhh, you're a thinking man Dmitry....

    That has been a bit of a top secret for a long time, but now that
    I'm selling the machines....it's only a matter of time before a few pictures
    get out. And...it's not that hard for someone to figure out...

    The 2 important questions are "How" and Why". We've got "How" taken care
    of.

    The *Big* problem with round shafts is how to get them aligned perfectly.
    And as anyone who's made metal machines knows, When sliding elements
    are separate, just tightening a single bolt most anywhere on the machine
    can cause binding some place else.

    So the trick is to make the whole slide a single part that's made to fit onto
    pre-aligned rails.

    Prealigning the rails is easy. Just take a few scraps of MDF.....bolt them
    temporarily together.....make a few cuts/grooves for the rails to rest in....
    separate them and when the rails do rest in the cuts, they're the exact
    same spacing apart. A temporary jig. Necessary.

    The spacing is now known.

    Make the actual slide plate....mdf in this case....and cut some more grooves
    for the bearings to be fixed into at the known separation of the rails. Then
    cut one groove in the dead center for the drive nut.

    Plastic and Oilite aren't good for direct gluing into place. The Delrin won't stick,
    and while the Oilites can be glued, they're not the ideal thing to be gluing. They're
    impregnated with oil. Common epoxies will work for awhile, but the oil will
    eventually cause them to pop off. Super glues can hold them well enough most
    times if enough coats are used.

    So the ideal situation is some type of glue-able transitional material. The bearings
    and nut is press fitted into a tube of some glue-able material. In this case common
    PVC pipe. But here's where it becomes a slight problem. The bearings and nuts
    don't fit without the PVC being bored or reamed. A lathe takes care of that.

    With the bearings and nuts correctly press fitted, the assembly can then be
    permanently glued into place with super glues. The super glue will permeate the
    softer MDF core material and a few applications make the whole assembly very, very
    tough and durable. The same basic process has been used on many, many machines
    and I've never heard of a single problem. In fact the very large 6 ft yellow machine
    I showed earlier was done the same way. Huge 36" slides with 1.5" I.D. bearings...

    So the slide is made to match the pre-aligned rails. It's all a single piece. It
    can't get out of alignment as it's permanently glued in place. I've never heard
    of one being damaged or breaking.

    The part is so strong and durable that the bearings and nut are replaceable by
    simply being tapped out with a thin rod of brass or hardwood.

    It's such a good, easy, permanent way to do it that it won't be long
    now for it to become the standard way to align bearings for MDF machines.

    Now that the secrets out....


    John



  11. #287
    Gold Member Mr.Chips's Avatar
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    Not only the picture but also detailed the construction methods, and why and why not certain material were used.

    Now here's a man that is comfortable in his own skin. And sharing construction methods that few sellers would. Gotta love it.

    Much respect to you John.

    Hager



  12. #288
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    Thanks Hager!


    John



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