Trying to get higher metal removal rates on the Boss - Page 2
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  1. #21
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    The mill runs one of those automatic oilers with tube work going throughout the mill. The ball screws are the type where the screw is bolted to the table and does not rotate while the nut is suspended on bearings and does the rotating.

    By material being removed, are you asking about my ci/min removal, or the total amount of metal being removed?

    Here is a picture of the part. It's a bedplate for a little engine. The original weight is 570oz on the stock and the finished weight is 167oz.

    currently, the time to machine that side is around 2.5 hrs. By the time I have the whole part finished, it's probably closer to 4 hrs.

    piece-being-machined.jpg

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    The spindle to motor ratio is a little off. the Vari-speed was set to 3,000rpm. Since I machine at that speed 80% of the time, I thought it would be good to put it there so the spindle motor is running at its base RPM for a majority of the work.

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    I have run mechanically identical machines for over 25 years

    so the math tells me a perfectly executed program at you max removal rate would take an hour.

    which means there is an hour and a half of not max productivity going on there

    program efficiency
    accel decel
    non cutting moves


    It would not surprise me if you could get the program to run 30 percent faster without cutting faster

  4. #24
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    Quote Originally Posted by F14 View Post
    The spindle to motor ratio is a little off. the Vari-speed was set to 3,000rpm. Since I machine at that speed 80% of the time, I thought it would be good to put it there so the spindle motor is running at its base RPM for a majority of the work.
    Try changing it to 1:1 and see if you get better torque

    pretty easy change to try

    [edit] BTW I don't think your removal is far off, if my memory serves, when we did real work on my R2C3 it ran about 5 cuin/min in 6061

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    Looking at the head design of this mill, I am noticing that it could be altered to fit a bigger motor, but it would be a big pain in the butt to modify everything needed to make it happen. Especially if I wish to save that bull gear and I do. It's indispensable when I want to use my cut off saw and my 1-3/8" drill bit.

    For the others that have given me their input, thank you. I would conclude that I should probably just leave this mill alone and keep going with it since its paid for. Sounds like the easiest thing to do would be to go into Fusion 360 and play around with the tool paths and further develop them to get a better cycle time out of the mill.

    Yes, I would agree that it would be best to go and purchase another machine that is a peg up from what I have. Possibly go from my 3,000lbs up to a machine that is in the 6,000 + lb range. My shop is little and can only handle about 10hp of wattage on the best of days, so that may be my limit unless I expand.

    I guess the only thing to think about now would be what mill I should plan to get this following year.

    I will say that my biggest gripe about my mill is not the power, but the table travels. I only have about 16" on the x and 9" on the y. The Z is about 4.5". So, if I end up going as far as getting another mill, then I would like to see something like double the travel on the X and Y so I have the option to work on some bigger things if the opportunity comes up.

  6. #26
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    should be 18x12x5

    yeah, its small, but a pair of vises you can make money

    Again, on tool paths it is possible older is better because of the slower rapids, but perhaps someone will chime in who has done this kind of programming on this type of mill. Mine is mostly used for drilling holes and gov't work now.

    But it made a bunch of chips over a long time. I bought it practically unused in 1992.

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    At least try a corn cob rougher, they do use quite a bit less hp. The chips are a lot denser so you may have trouble clearing them. Also minimize the projection of the tool, stiffer is better.

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    Quote Originally Posted by F14 View Post
    I generally run the machine at 3000 RPM. What I have done is put the Vari-speed in one position and I have left it there as if it was a single-speed system. My VFD takes care of the rest. I grabbed one of my model airplane propellers and put it in a tool holder and ran my optical tach on it to correctly match the RPM on the control with the true RPM. This way, I could get automatic RPM adjustments running the s-code in the programs and I could be hands-off. I have set the mill to run at a max of 5,000 rpm. It actually runs very smooth up at that speed, but I noticed that its really only good for 1/4" end mills or smaller at that speed. I just loose too much torque up there. Not to mention that when I cut aluminum, I use those Alu-Power end mills and at that RPM, it kicks an aluminum rooster tail that shoots aluminum about three feet outside of the table. Then I have to hit the deck and low crawl.

    The mill uses 750W Estun servos on every axis and it is set to rapid at 300ipm. I do have the accel and decel rates set to where it tries to be gentle on the ball screws and not bang them around with near-instant delta-V. That means that if I am only going to rapid two inches over or so, then I may make it to 200ipm before a decel occurs.

    On aluminum, I have been able to get the mill to give me 6ci/min metal removal, but the spindle will not keep a true 3,000 RPM and will bog down a bit. So, I will generally shoot for 4+ci/min and be happy with that.

    on steel, the best I can hope for is around 1.5ci/min. So, I have stayed away from machining bigger hunks of steel because of that and focused on smaller projects if made of steel.

    Look at my post 11 As you have a VFD already you could check if it is possible on yours
    That way you get constant torque even over 60 Hz So more HP
    At normal settings a VDF can hold contant torque up till 60 Hz Up 60 Hz he cannot supply the needed higher voltage to the motor any more
    By setting the motor at a lower voltage as the supply the voltage can go up above 60 Hz
    Keep in mind that Amps is higher at low voltage of the motoer So your VDF schould be rated for that

    Peter

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    My VFD is not vector control. It is only an inverter. I would probably go for a GS series VFD from Automation Direct to have that option.

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    I think,again, you are losing most of your time in places where the machine is not putting out max horsepower.

    IT you had to rough those two pockets in a 1950 kinda way with mechanical stops on a manual bridgeport, how long would it take?

    Math says an hour, so, where does the time go?

    Just guessing , bad machine parameters and bad [for your machine] tool paths. I would examine how much time is spent moving without cutting metal and rapiding point ot point. CAM paths tend to do a lot of stupid things that we ignore with 2000ipm rapids

    In my own experience I never saw much point in getting the machine over ~2200 rpm when trying to take a chip with a 3/4 end mill.

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    Quote Originally Posted by gustafson View Post
    CAM paths tend to do a lot of stupid things that we ignore with 2000ipm rapids
    But but but ... that's archaic thinking ! What are you proposing here, a return to the 1980's ?

  12. Likes gustafson liked this post
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    Well, the machine was built in the 80's

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    Got curious. Looked up my old machine parameters

    Z accel was .2 meters/sec^2
    X was .25

    IF I did my math right, 300 ipm in half a second on X

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    Quote Originally Posted by gustafson View Post
    Got curious. Looked up my old machine parameters ...

    IF I did my math right, 300 ipm in half a second on X
    Santa Cruz Mike had a late-model Chevalier with a current control. He picked up an old ExCell-O 104 with an outmoded Bendix and old-technology DC Getty's drives, Luddite Edition.

    Ran the same parts on both machines, same program and tooling even, and the 104 was about 15-20% faster. Them oversize DC drives shit-n-git

    The 104 is a nice little machining center.

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    Quote Originally Posted by EmanuelGoldstein View Post
    Santa Cruz Mike had a late-model Chevalier with a current control. He picked up an old ExCell-O 104 with an outmoded Bendix and old-technology DC Getty's drives, Luddite Edition.

    Ran the same parts on both machines, same program and tooling even, and the 104 was about 15-20% faster. Them oversize DC drives shit-n-git

    The 104 is a nice little machining center.
    I figure I could turn the OPs blank to chip were it 6061 in about 45 minutes on my R2C3

    about 5 on my DMG

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    Quote Originally Posted by F14 View Post
    My VFD is not vector control. It is only an inverter. I would probably go for a GS series VFD from Automation Direct to have that option.

    My solution has nothing to do with vector controlled or not

    Peter

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    Quote Originally Posted by F14 View Post
    Here is a picture of the part. It's a bedplate for a little engine. The original weight is 570oz on the stock and the finished weight is 167oz.

    currently, the time to machine that side is around 2.5 hrs. By the time I have the whole part finished, it's probably closer to 4 hrs.
    piece-being-machined.jpg

    Do they still have castings back there in Ohio ?

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    Sounds like instead of that controller upgrade you shoulda grabbed a fadal vmc 15 for prob under 8k.

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    Hey buddy, I'm in the process of putting a 5hp baldor vector rated washdown motor on my boss 8. I've got all the design done and have machined most of the metal for it. I'm retaining the low gear and original brake and using a poly v belt. This motor make 5 hp up to 5500. With my pulley ratio I'm getting 2 hp (or higher) over the entire original rpm ranges 500-4200 and 50-500. These blow away the standard bridegport in terms of rigidity. So I think the 5 hp may turn out to be very useful. I'll start out limiting my cuts to 2 hp, but I will experiment using full power available. I'll be keeping a close eye on bearing temp in the spindle. I'll tell you now, there is no way your fitting this motor in the original position. It has to point up. I'll upload my designs to grabcad soon. Be advised I'm not sure if the dowl pins are hand drilled or not my model may not work for you. Their position is a little funky. It took some work but I was able to accurately measure their position on my casting.

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    some cnc if servo feeding X or Y is under enough load it actually goes slower than programmed feed rate
    .
    just saying if you program 60ipm is it actually moving 60 inches per minute ??


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