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    Default Check out my 2nd cnc

    A bit of details:


    Couple of cuts:




    The whole thing took 4 and a half months. The 1st cnc...8 months.
    See that one too:
    Pololu robotics forum - View topic - CNC prototype

    Word to beginers: do not give up.

    Similar Threads:


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    Very nice. It seems to machine Al just fine for most uses.

    I particularly like the raised side rail design - that makes for a very rigid upright vs the risk of wobbly uprights on a moving gantry.

    Is there a reason that you had to make your own circuit board to pull it off - that is a leap of faith for me.

    It looks like there was some cutting fluid being dispensed, was that you or does your machine spray some before the cut ?

    Congrats.

    Harry



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    Thanks harryn.
    I'm glad you noticed the top and bottom support on the gantry. It makes it so much more rigid than just bottom support. Down side is that you need 2 motors on Y.
    It took me about one and a half months just for r&d. A lot of good info can be found here:
    Do it yourself CNC router: Design Considerations, the Gantry

    As far as making the electronics I only made (designed) the motherboard. The drivers are from pololu. I wanted to design a PCB for a long time so this was the perfect ocassion/challenge. Not to mention way cheaper than what you can buy. I would guess about $130 in electronics and $80 for the motors. Imo it's great price for 4 stepper motor setup.

    Using pro tap cutting fluid. I sprayed it before starting the cut.
    I wish I used it last night . Serious chip welding. I wanna post that on youtube as well, for a learning lesson.

    Working on a flood system after the one I got from MicroMark didn't event start. Went ahead with the cut and I payed for it.



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    bg_blea,

    In those videos with all those aluminum shavings....don't they get into the lead screws and bearings and jam stuff?

    newpatch



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    The only spot where it might be a problem is the the bottom of the z axis. There is a retaining ring that hopefully does the job untill I come up with smth better. Like a flood system or vacuum.

    Other than that screws and bearings are clean.



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    hey bg_blea, very nice job you did and pretty original, congrats

    What kind bit you are using to cut the aluminum in your videos and at what speeds?

    I never cut aluminum with my CNC but I plan to do so in the near future and somehow I thought the speed you are using is too fast

    Nicolas


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    Thank kolias.
    One of the vids has the details:
    3 flute carbide, 1HP Bosch Colt, 16K RPM, 48 cut IPM, 10.5 plunge IPM , 1/32" DOC.

    The end mills are from McMaster made by Niagara. If you;re running a router I suggest you look into a collet like the ones from precise bits. Here's a reseller Router Accessories - Collets for Porter Cable and Bosch Routers

    Why do you think it's cutting to fast?
    Theoretically 48IPM/ 16K RPM * 3 flutes = .001" chip load.
    Practically chipload (kindda hard to measure it) is about .006".

    I plan on running at 1/16 DOC (I did that at 48 IPM and it works just fine) and increase the feedrate and the rpms. Router will do 35K RPM so... 105IPM.. wow. Hope it can make it.

    Before all that I'm working on a flood system maybe a week or so.
    3 more vids coming up.



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    Thanks for the info and the link

    I have no experience cutting aluminum and it looked like too fast for me. Glad it’s working out for you.

    Regarding the 3 flute carbide, some time ago I read that cutting aluminum is best done with 1 flute so when the times comes I will give a try with both and find out the results

    Good luck with your flood system

    Nicolas


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    I don't have much experience at all either .
    One thing I red online was that 3 flutes is a magic number to avoid chatter.
    Smth to do with resonant frequency of Al. The guy has a Phd. Lol.
    I ran 2 flutes as well and it worked great.
    From what I get the less flutes the better chip evacuation the more flutes the better the finish.



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    Makes sense in what you are saying about less / more flutes

    Guess when the time comes I will order 1, 2 and 3 flutes and then I will know exactly which one does the best job.

    Nicolas


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    Default flood cooling



    Still work to be done but it works.



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    Nice job bg, you are heading the right way

    Nicolas


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    Default controling coolant splash





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    Default Bellow covers or blinds, origami, rubber spray

    I've abandoned the flood cooling in favour of mist after a few emails with Bob Warfield. It's all DIY and the coolant is provided by an IV line. I can control the flow precisly.
    It works great but chips were getting all over. So... bellow covers.

    Instead of starting from scratch I use RediShade blinds. These are temporary blinds and are already pleated. They sale them in paper and plastic of sorts. I used the plastic ones.
    With some origami I made the 90 degrees. It's actually quite simple after you try it a few times and you really don't have to do any prep folding, saving a bunch of time.
    Finaly a FlexSeal (rubber spray) coating.
    Each fold has a grommet (that wasn't fun) so the covers don't bend out of control and also because I suspend the covers.

    See the images:




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    Quote Originally Posted by bg_blea View Post
    I've abandoned the flood cooling in favour of mist after a few emails with Bob Warfield. It's all DIY and the coolant is provided by an IV line. I can control the flow precisly. [/url]
    Hey bg, good work.

    Can you give me some details of your cooling system? Like what kind coolant you use, how you control the flow and where did you buy the parts.

    I'm designing mine right now and looking for ideas

    Nicolas


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    Thanks.
    In the video pause at 0:52.
    Starting from the bottom:
    - you can see the any which way assembly
    - connected is a 1/2" inch tube
    - just above the connection there is the iv line inserted into the 1/2" tube and some messy glue to hold and seal
    - at the top of the image there is a blue thing. That is the drip control for the iv. It has a roller that crimps the iv line thus controlling flow. There is a larger tube where you can see the drips. Just like in the movies . Probably on youtube as well. This in turn is connected to whatever holds your cutting fluid
    - at the other end of the 1/2" I have a small shop vac that blows a hurricane.

    I use TapMaggic for fluid and the iv was from Amazon. Get the lower count drops per ml. If memory serves I use the 10 drops/ml.
    Good luck.

    forgot to mention that the roller crimper thinghy comes with the iv line and you can get a saline bag that you can use.

    Last edited by bg_blea; 07-18-2012 at 09:13 PM. Reason: missing details


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    Thanks bg, vey interesting

    Nicolas


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    Default To spindle or not to spindle

    Few things about Bosch Colt...
    I ran the machine some time ago and I noticed the collet nut getting very hot. Ran it for 15 minutes at 35k RPM. After that I ran the thing with no load and again it was getting hot within couple of minutes. Damn.
    The part was off here and there for up to 0.02". Might as well cut it by hand.
    I measured the TIR and I got 0.002". WOW.

    I took it apart and the bearing doesn't look good at all . No surprise there, it is a router after all. Found some chips inside as well. I guess that propeller can only do so much. Not very comforting considering coolant can get in there and potential to let the magic black smoke out.

    Besides that:
    - the lower bearing sits inside a plastic ring that is tight fit or glued to the bottom metal housing. No wonder it doesn't dissipate heat.
    - the bearing reads: 6002RS B21-17 Outdo. Guess the 'Outdo' is some manufacturer, no clue what 'B21-17' is, but 6002RS gives the spec to find the bearing. Looked that up on VXB and what I found is rated for 15K RPM. Maybe this one is specially made for Bosch and has different specs but otherwise scarry to think a 15K bearing running at 35k RPM.

    I was in the middle of getting smth done so I went and bought a second colt. Quite pricey at Lowes $120. 1st I got was refurbished from CPO outlets and was $80.

    Having 2 of them I thought of a great project. How about I replace the bearing and that plastic junk. Maybe find a way to keep the debris out of the router and provide better cooling.
    While it would be a fun project here's the bottom line: I'm at $200 bucks in routers. If I double that (more like x2.5) I can get a nice spindle with inverter, plenty horse power and can run at whatever RPM I want. If you're new to CNC like I was 2 years ago, being able to run low RPM for large endmills is very important .

    Not sure if I will end up buying one but seriouslly thinking of a belt driven one that I can design.

    Here's me punishing my new Bosch Colt making a part to replace the plastic bearing housing. Precision within 0.00075" (angular bearing on the way). CAM software would just not generate the ramp so it's brutal... Check out my final cooling system as well.





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    Replacing the plastic with aluminum didn't work so well. Now the entire lower part of the colt gets hot
    Time to get a quote for a belt spindle.

    Check out what user 'mactec54' makes:
    http://www.cnczone.com/forums/cnc_wo...dle_build.html
    It is just beautiful.
    Anybody know where I can get a small/compact 1kw ac motor?



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    My alternative for a belt spindle was a Taig Spindle along with a VS Sherline DC motor. So far I'm very happy with the results

    I was also looking at the Hitachi VFD but it requires 220VAC which I dont have and their 120VAC unit needs 25A breaker which I dont have either. The cost to get the cable / encosures to equipped my garage with this volt / amps was to high for me and so I went with the Taig

    Nicolas


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