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Thread: 1931 Model A Victoria build

  1. #71
    Senior Member Robert's Avatar
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    Really cool. You are starting a dedicated thread right?
    I am looking at mills and learning Fusion 360 at the same time. I am torn between the PM 727 and converting it later and just buying a PM45 CNC. Are you saving a lot by doing the conversion yourself?
    Impressive toy.
    Robert
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  2. #72
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    The conversion to ballscrew from Acme (or whatever the factory ones are) appears to be no small feat both in terms of labor and expense, yet there appears to be no hesitation on your part to do it, nor is anyone questioning it. So it's evidently a no-brainer as they say. I have very little real knowledge of them. I have them on my CNC router and on one of my bindery machines and they work fine. I've even had the unpleasent experience of having to repack one a couple of times. I have a number of Acme threaded lead screws on several machines at home and at my printshop as well and Im quite aware of things like backlash and wear that are clearly much less. - basically nonexistent- on the ball screws. The few automated acme threaded machines I have have encoders on them and are designed to overshoot their target and then dial themselves in as part of their design which I understand is a whole other level of gizmos and complication.
    I guess i just don't have enough technical experience to full understand their respective applications. I know what the two types are, I know how to use them, I have a pretty good idea how they function, but if the ball screw is really hands-down that much better, why don't new machines come with them already on them? Whether it's a mill or paper cutter or any other device for that matter? Why isn't the acme obsolete in these types of applications? Is it just the money?
    Inquiring minds want to know, lol

    Pete

  3. #73
    Moderator DavidF's Avatar
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    Im saving about $2,000.00 by doing it myself, but the main reason for doing it myself is that I want things a particular way. One of the biggest obstacles to overcome is eliminating the back lash or as much of it as possible. I will be shooting for no more than .0005" backlash to accomplish this Im using double nut ball screws that I will modify slightly with belleville washers to keep the ball nuts preloaded at all times.
    Im also somewhat thinking about making patterns and casting the stepper mounts. You never know might be able to sell a few "kits" But thats still up in the air.
    I just started designing the mounting for the Y axis tonight, but think I may be down for the count. Feeling sick as a dog...

    Petee, ball screws are expensive compared to acme threaded rod Im not sure if that is the only reason they are not used more nut I would think that is a major part of it especially when you start getting into the c3 ground ball screws.

    Robert, Im in about 4500.00 so far and to buy this machine as a pre assembled cnc it would run 8K But there are some things I don't like about their conversion. The PM 45 is a nice sized mill. My problem is and has always been with the Y axis travels on most every bench top mill Including the tormach 1100. With the PM 940 I will get 13.5" of usable Y axis and could likely get a bit more if I added a head spacer.
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  4. #74
    Senior Member Robert's Avatar
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    Um...I hope you will be willing to guide me through my conversion! My current floor cannot support the PM45 so that's where the 727 comes in.
    By the Y axis do you mean vertical or front to back?
    Feel better.
    R
    "Whether you think that you can, or that you can't, you are usually right."
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  5. #75
    Moderator DavidF's Avatar
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    Quote Originally Posted by Robert View Post
    Um...I hope you will be willing to guide me through my conversion! My current floor cannot support the PM45 so that's where the 727 comes in.
    By the Y axis do you mean vertical or front to back?
    Feel better.
    R
    Y axis = Towards you.
    Ill help you out if I can.
    A calm sea does not make a skilled sailor...
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  6. #76
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    When i was learning the mill the man in the know that was coaching me said to think of the 'Y' axis as an arrow. ...drawing it back toward you and of course shooting it directly away. The 'Z' is a spring, and therefore the vertical axis. Can't recall the story behind 'X'... But that's the only one left so it's kinda a no brainer...lol
    FLAME ON...!!!!

  7. #77
    Moderator DavidF's Avatar
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    Quote Originally Posted by J. Vibert View Post
    When i was learning the mill the man in the know that was coaching me said to think of the 'Y' axis as an arrow. ...drawing it back toward you and of course shooting it directly away. The 'Z' is a spring, and therefore the vertical axis. Can't recall the story behind 'X'... But that's the only one left so it's kinda a no brainer...lol
    If you look at the videos of the Grizzly, you will see blue tape on the top of the head with he cords marked out. Saves me from at least one brain fart when zeroing out the stock.

    Oh, that bar in the center represents the stock and the + - is the tool bit.....
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  8. #78
    Moderator DavidF's Avatar
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    Pretty much finished the Y axis....Botched the video though....
    A calm sea does not make a skilled sailor...
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  9. #79
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    DavidF, what happened to the '37 Victoria build?

    Chuck

  10. #80
    Moderator DavidF's Avatar
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    Still working on it Time has been short lately though. Mostly trying to get the new cnc mill finished then I can get back on the vicky.
    A calm sea does not make a skilled sailor...
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