FreeRiders V-Bearing Modified Momus - Page 2


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Thread: FreeRiders V-Bearing Modified Momus

  1. #21
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    Quote Originally Posted by momus_cnc View Post
    Beautiful craftsmanship, and great build log!

    Yeah, the plans are dimensioned assuming an exact .750" thickness, which it obviously never is. This isn't much of a problem when cutting with a table saw or circular saw, as the tolerance most people can hold with those tools is greater than the thickness deviation from the ideal 3/4". But when using CNC equipment, it would be best to adjust dimensions based on exact material thickness, so you get the very best part fit. The best situation would be for me to create a parametric model of the base one of these days, so that all you need to do is input the true material thickness, and all of the other dimensions would automatically adjust based on that.

    -Bob
    Bob,

    Thanks for the compliments! Your build was quite a fun one to go thru (even in my modified fashion). I figured that I would have some loose dado's and overhangs here and there (due to the 0.750") but laziness got the best when I was converting the plans to drawings.

    A parametric drawing would be a nice addition for the OCD among us...roll it into revision 3?

    Once again many thanks for publishing your design, I am still blown away by the amount of detail and pictures you provided with the plans.



  2. #22
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    Default Cutting With Coolant

    I still have yet to build an air diverting clamp for the router but I decided to run a cut today in aluminum with a little bit of cutting fluid. I found that plain old rubbing alcohol works quite nice as a lubricate/coolant while leaving zero residue behind to clean up. I filled an old spray bottle up with a bit and gave the cut a shot here and there. I also add another layer of MDF to the bed when milling aluminum to help move the z axis closer to the center (more rigid).



    The cut quality has increased significantly with the "mist" system. Edge finish still isn't exactly what I'd call perfect but its more then adequate...especially for not having to cut by hand. What has increased for the better is the tolerance. I have now moved from the high side of 10-15 thousands down to single digits which is more then I expect a belt driven DIY machine to produce.



    Here you can see the tool deflection from ramping up and down my 3D tabs. Next time I'll fixture the part differently to avoid tabs...or work on increasing the strength in my z axis. The diagonal marks are from a hand file used to remove the remainder of the tabs.



    One area thats nearly perfect are the slots and holes. While still out by 2-5 thousands the finish is quite nice and uniform (not a mirror finish, but then again I never did take a finishing pass). All these cuts were taken at 30IMP with a DOC of 0.01" and a spindle speed of about 12000 on a 2 flute 1/8". Next time I'm going to try increasing the feed to ~60IMP as I have the ability to spin much faster while still keeping a proper chiploading.



    Heres a couple quick shots showing the actual measurements right off the mill (after filing the tabs away).



    Heres the long dimensions which is where I see the greatest error...still not too bad. I could probably tram my spindle a little better and knock off a couple thou. I should also note that I am using endmills with a tin-al coating which is NOT a great choice for aluminum. None the less I can get these locally for cheap and they have been working well, my aluminum 0-flutes do leave a little better finish but they are also about 4 times the price! Also nice cutters since I can chuck them up into the little taig and mill steel without troubles (thats where that coating works well, high speed, high heat in steel).



    Thats all for now, next thing I'd like to try is a full depth finishing pass on a few parts and see how nice that can clean up the edge. I'm also going to experiment more with high feed but small DOC cutting in aluminum, seems to work nice on these less rigid machines, keeps the cutters nice and cool too .



  3. #23
    Registered vtxstar's Avatar
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    Outstanding!

    I would love to get parts that close and you are setting goal for me.

    At this time I am in the fill/file/sand/repeat mode on the base and cover prep and finish.
    My biggest errors were in cutting the windows. The rotary cutter did a great job when I kept it straight.
    It did a great job of making more work for me when I didn't keep it straight! :O

    When tired of that the two electrical chassis for power and control are progressing nicely.

    What I really need to do is edit and upload the pics I have taken...otherwise it is just talk, talk, talk...

    Carry on! Well done!

    -=Doug

    Last edited by vtxstar; 04-25-2013 at 08:18 AM.
    "IT ≠ IQ " Starwalt 1999


  4. #24
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    Default More than talk, talk, talk...

    Taking a dose of my own medicine, here is a shot of where the fill, sand, finish stage is...

    FreeRiders V-Bearing Modified Momus-100_5162-jpg

    -=Doug

    "IT ≠ IQ " Starwalt 1999


  5. #25
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    Outstanding Freerider, looks great!
    I am too enjoying the detail you describe everything with and the pictures, keep it coming... :-)

    Very cool are your exploits with the bits and results you are getting. I've never thought about introducting coolant into this machine, but the great results speak for themselfes.
    Thank you, I'm getting a lot of ideas from what you are doing for my machine and at the same time what to expect.
    Yours sets the bar pretty high already, lol.
    --
    Mac



  6. #26
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    Quote Originally Posted by vtxstar View Post
    Taking a dose of my own medicine, here is a shot of where the fill, sand, finish stage is...

    FreeRiders V-Bearing Modified Momus-100_5162-jpg

    -=Doug
    Doug thats looking great! I love the tidy electronics installation. Thats the only part about finishing I hate, build it all, then break it all back down to make it pretty. Hard to bring yourself to do it.



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    Mac,

    Thanks for the kind words, but after seeing your build thread I know you are no stranger to high quality craftsmanship.



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    Ohh, I wouldn't call it that quite yet, but thank you too!
    Inspired by the great detail in yours and previous build treads from other builders, I decided to take the evening off and post some my build exploits with a LOT of pictures tonight.
    I've got a lot of catching up to do with that thread, lol.
    Check it out... :-)
    --
    Mac



  9. #29
    Registered P.Passuello's Avatar
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    Excellent job and great use of the V bearings in your design.
    Much easier to build and adjust.

    Cheers
    Peter

    The ingenuity of idiots is unlimited.
    http://www.youtube.com/user/cncnutz


  10. #30
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    Default Cutting Thicker Stuff

    First off many thanks for the kind words all, been working this CNC and the one at work quite hard lately and been lacking on my internet updates.

    Here is a photo of the latest work to come off the momus. Its a section of 1/4" 6061 used to mount a brushless motor for an electric bike project I have been working on.



    I noticed I get quite a bit of chatter when I push the small 1/8" endmills thru aluminum so I decided to see how hard I can push a 1/4" 0-flute. This cut was taken at 0.015" DOC with a 60IPM feed rate. I used a 3* ramp to start the cuts and gave it a light blast of alcohol whenever it sounded a little rough.



    The edge finish is not quite perfect but I think its the best I am going to get with these feeds on this machine. My router was turning at about 1/2 speed during these cuts which resulted in a 0.005" chipload (measured and calculated). Most people think your doing your machine a favor by upping the router speed and decreasing the feed but more often then not your just prematurely dulling your cutting edges. Next cut I am going to ramp my "spindle" up to its full speed ~24k rpm and push the mill around at 90-120ipm and see what happens...when turning that fast 100IMP is about as slow as I can go before getting below the minimum chip load.



    There is some minor evidence of stair stepping on the inside cut as I was moving a little too fast when pocketing that one. Outside profile has next to no evidence of stair stepping which has me impressed! This was just a prototype part to iron out the details, the next version will be cut from 1/2" later this week, I may also include some fancy surfacing operations and deep pockets so it will be interesting to see how the machine copes.

    As always I will photograph my adventures, probably also snag a video of this next cut as the chips form soooo well when using the nice 0-Flutes.



  11. #31
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    nice work on your build...
    In post #1 the frist picture of that cnc... what brand is the cnc ,or is that a dyi unit... I would like to know more about it if possible



  12. #32
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    Nice work. I am interested in how you got out the pdf pages that you converted to dxfs? Would you be willing to share the pdf pages for the wood parts? I would be glad to pay you. Thanks. Mike



  13. #33
    Registered momus_cnc's Avatar
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    Nice work. I am interested in how you got out the pdf pages that you converted to dxfs? Would you be willing to share the pdf pages for the wood parts? I would be glad to pay you. Thanks. Mike
    Mike, there may be a bit of an intellectual property issue in asking for that kind of transaction. Are you looking for dxf files so that you can CNC cut the wood parts? If so, get in touch with me directly.

    If this is what you are hoping to do, one thing to consider is the thickness of the material. The plans are dimensioned assuming the material is an ideal 3/4" thick. In reality it isn't (23/32" is common). This ideal dimensioning works fine for most people cutting out parts with a table saw or circular saw, since their cutting tolerance may likely be greater than that 1/32" difference between ideal 3/4" and actual material. But if you are cutting parts on a CNC machine, which has a much greater accuracy, it makes sense to use dimensions based on the actual material thickness. So I would suggest purchasing the material, and carefully measuring its thickness. I would then look closely at the exploded view drawings in the plans to figure out which pieces would need minor size adjustment. Then redraw the parts in CAD, with the small dimensional changes made. They are almost all simple 2.5 axis parts, so redrawing them should take very little time.

    -Bob



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    Default Re: Router Mounting

    Sir, It is a very nice built, I am planning to built the Z-axis exactly like yours. It looks much more simpler than the original Momus design. I have purchase the Momus plan and now studying every detail especially the Carriage and Z-axis, looks very complicated. I like your design very much. I have ordered the V-Groove bearings and use it as the X, Y and Z rails. After looking at all your pictures, I just wonder how do you connect the Z-axis stepper motor plate to the body of the Z-axis. Can you kindly post a more close up of that connection. Do you bolt it to the wood panel? Helps me alot in constructing my new CNC machine. Thanks



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