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Thread: Let's Talk About Table Flatness

  1. #21
    Join Date
    Mar 2004
    Location
    Delray Beach, FL
    Posts
    3,647

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    Got to throw in with the other side of the coin. A SB, which is a fabulous machine for the money, is not a super high resolution big iron machine. If you go into it with the appropriate expectations then you will be amazed. If you expect unreasonable perfection then you have only yourself to blame for your over inflated expectations and resulting disappointment.
    I could make parts that competed with the big boys on quality any time, but they did it fast and easy and for us it took a lot of tweaking, patience and time. Brady has gotten more out of his mills than darn near anyone could. He is also the first to admit the immense amount of time and effort in mechanical education it has taken to do that. Nothing wrong with that at all. Fabulous in fact. But, that is also far beyond what most mill clients want to have to do. Note that when it comes to flatbed mills they all end up in the same place though, There is a spoil board thrown on top of the plenum. The spoil board changes shape during it's life. That affects part production. Learning how, when, and what to do about it is what separates the Pros from the Ams. No matter how flat, stiff, and non reactive your base below it is, the spoil board above and the live part you are cutting are still the final variables to deal with. To do that we don't need to be Scientists. Artisanship is plenty sufficient.

  2. #22
    Join Date
    Jan 2004
    Location
    iBILD Solutions - Southern NJ
    Posts
    7,853

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    Dave,
    Where are these 'mills' you speak of? My mill weighs 3800# and is made from Mehanite cast iron. It's heavy enough to cut tool steel within .0005" reliably. My CNC router, with a machinable area over 53 times that of my mill, maybe weighs half that. I'd like to find the first dweeb that started the trend of calling machines even lighter than a ShopBot a 'mill' and slap them with a wet noodle. Many of these machines barely qualify as routers, let alone anything resembling a mill in the traditional sense. Some are calling some of these glorified plotters made out of plastic of all things 'mills' - please stop!!! JUST STOP!!! It's ignorance polluting & corrupting our language, and minimizing the efforts of legitimate millwrights and pattern makers - which were and are at the top of the machining pyramid.

    Though my illusions and delusions over the past 17+ years of working with these 'light POS machines', I've managed to turn out countless iconic projects a lowly ShopBot owner/operator has no right doing. In fact, several jobs came my way via big iron turning it down because they were literally too slow doing 3D (by the customer's voluntary admission), didn't have provisions for holding the part down (using something other than universal vacuum), or were just plain out of their element in doing the job (scared)...

    They say a poor craftsman blames his tools...I say a good craftsman invests in the best tools he can afford and maintains them like they are the lifeblood of the business. Furthermore, since these machines are electronic, they also need to keep up with the times, upgrading them to something newer than WinXP/2005 technology and mechanical components that improve the end result. I've been to too many shops where they beat the hell out of their ShopBot and never maintain it...and more often than not, 'upgrade' the machine with half-baked solutions that are worse than the OEM/stock configuration. Very few even clean their machines of dust/chips, let alone check, adjust or lubricate them. "That's just the way it is." - isn't spoke too often 'round these parts.

    So to some, the idea of spending $2500 or so, plus all that labor to get the table surface the way that I want it to be seems crazy. I get that. But if it isn't reliable, or meeting my expectation of what it should be, I'm the kind of guy to put my best effort into it and make it right. No different than a guy with an early PRS 5x12 with 4 legs wanting to get the sag out of the table. If I machine parts and they aren't up to my standards, they don't leave the shop until they are done properly. All ego aside, my name means something. People know they aren't going to get junk when they deal with me - so it's my responsibility to always do my best - and that means, not turning a blind eye to deficiencies in my equipment, that can be corrected within my means. The foundation of the machine affects everything above it.

    “...like a wise man who built his house on the rock. The rain came down, the streams rose, and the winds blew and beat against that house; yet it did not fall, because it had its foundation on the rock. But everyone who hears these words of mine and does not put them into practice is like a foolish man who built his house on sand. The rain came down, the streams rose, and the winds blew and beat against that house, and it fell with a great crash.”
    Rock on...

    -B
    High Definition 3D Laser Scanning Services - Advanced ShopBot CNC Training and Consultation - Vectric Custom Video Training IBILD.com

  3. #23
    Join Date
    Mar 2004
    Location
    Delray Beach, FL
    Posts
    3,647

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    Hundreds of things are properly called mills besides a metal working tool, starting with those places that grind grain into flour. Other than that we're pretty much peeing on the same tree as per usual! Getting what you do out of your tools is based on your extreme attention to detail, regular maintenance, and creative thinking. That isn't the norm out there. Like you, I've walked into shops where the owners had told me their machine was no good and in reality the issue was poor set-up and operation.
    By the same token, the average user cranking out cabinet parts or v-carved craft signs isn't going to need the absolutely perfect bed either.
    Sharing the knowledge for those few fanatics that do want or need to go the extra mile for absolute optimal results though, is always a good thing. Maybe a bit of it will seep down where it will help others as well!

  4. #24
    Join Date
    Feb 2012
    Location
    Los Angeles
    Posts
    14

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    Hello.
    May be my first post here. Lurker/learner forever though.
    Have a question and think this maybe a reasonable place to ask it.
    Any input appreciated.

    I have a 24 x 48 Buddy standard with the HSD.
    Love the machine.
    Bot at home...Fadals at work.

    Now taking a leap into a small personal production run of something I developed on the buddy.
    Will purchase a longer stick so I can run 48 x 48
    Will also build a 48 x 48 bradyvac with 2 Feins.

    If one of you were going to do that..today..what would you do for a base to use all of that new powerstick?
    I can give up some Z as I only ever cut panels....so i've thought about a box even.

    I am simply routing 1/4inch (6.5mm) melamine board into parts with .125 carbide endmills...and want to get Z cut depth as consistent across the field as I can.

    The product would benefit from equivalent depth in all pockets....so want to plan the new setup to FOCUS on that.

    Would the Buddy support moving a slab of Aluminum?
    Would it kill the steppers?

    How about a glue up of Formica..flattened?
    Would probably weigh almost as much.
    Money is an object for me...but still curious as to best option.

    Current base on the 24 x 48 setup (will be replaced) is 1 inch high quality subfloor ply.

    Any input appreciated.
    Last edited by mporter88; 11-30-2018 at 06:22 PM. Reason: Just adding details.

  5. #25
    Join Date
    Jan 2011
    Location
    gleason, wi 54435
    Posts
    412

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    my vacuum system has been much more stable since I made my plenum out of corian. I have 2 5 horse becker pumps that can be run solo or n tandem with a combined volume of about 175 cfm at 25 inches of mercury. I don't recall the numbers but the corian had less expansion / contraction than aluminum. keep in mind that when you surface your spoilboard the vacuum is severely reduced (especially with a high vacuum pump) compared to when you put a sheet on to cut and cover all of that open spoilboard. We would get some bowing (I seem to remember about .018-.020 inches) even on the Komo vr 510s toward the center of the spoilboard. Bob

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