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A question about carbon fiber

Discussion in 'CNC Mills/Routers' started by Steven Bloom, Feb 23, 2017.

  1. Steven Bloom

    Steven Bloom Veteran
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    Hi All, So I built my CNC machine last year and it works okay, Why I say that is that it gets bogged down a bit due to all of the weight I added. This mainly happed becase I used 4.5mm stainless steel plates for everything. And that adds like 40lbs to the machine.

    So this is my question. I have found someone to make me the same parts that I made in stainless before but this time in 4.5mm 3K carbon fiber. The replacement of the parts would e a simple swap in and out. The motors would run a lot better.

    But my question is would the 4.5mm carbon fiber be stiff enough for this kind of applicatiion. Has anyone else done something like this and had positive results ??

    Thanks Steven
     
  2. Jonathon Duerig

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    Hmm. This makes me slightly nervous because I just ordered some steel plates for gantries. What motors were you using? What part gave you the most trouble with the weight?

    -D
     
  3. Steven Bloom

    Steven Bloom Veteran
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    the biggest nema 23's i could find. I also made custom stainless steel gantry plates. The motors work but I have a feeling that it may be causing a little deflection in the C-Beam as well. Biggest problem is the 2 y axis motors. They are carring a lot of weight. The X and the Z work pretty well,

    Thanks Steven
     
  4. Jonathon Duerig

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    Ok. I'll have to see how it goes. I've got additional weight because I'm using a steel rack for a rack and pinion drive. I do have a 3:1 reduction so that might help. On the plus side, I don't think my C-Beam is going to deflect. I've got it super well-supported.
     
  5. alex_b

    alex_b Veteran
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    Hi Steven, I work with carbon fiber and G10 alot,(all my C-Beam plates are G10) and it depends on the type of 3k carbon fiber. If the edges look "wavy" then that CF is likely not going to be strong enough, but if it looks like thin parallel, straight lines on the edge, it should hold up. I work quite a bit with 3.5mm CF and I think it should be strong enough for your application, but probably not any thinner. I think it would be worth checking to see if the CF has any "filler" before going that route.

    Cheers
    Alex
     
  6. Steven Bloom

    Steven Bloom Veteran
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    I just ordered the CF. It is going to be 4.5mm thick. The CF is solid and has no filler.

    Hopefully it will work out well. I will send pictures when I get it. They said around 15 days.

    Thanks Steven
     
  7. Kevon Ritter

    Kevon Ritter Veteran
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    What size is your machine? Nema 23's might just be too small. The largest I know of is 425oz.in. Mass is a machinist friend.

    I like carbon a lot and know for a fact that it shouldn't be an issue, but I don't know what advantage you would have in this situation. You're giving up one thing for another.
     
  8. Steven Bloom

    Steven Bloom Veteran
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    The machine is not that big. It has a working area of about 30 inches by 18 inches. I currently have 332oz nema 23 motors. I really think its the weight of the stainless steal parts. They are over 40 lbs, maybe close to 50. The build is called "Sea-OX" it is on this open builds site.

    I would hope the advantage I would have would be the ability to turn up the motor speed.

    Thanks Steven

    sea-ox.jpg
     
  9. Jonathon Duerig

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    Honestly, it might just be the 1 meter lead screws. My current machine uses them and I can't go over 650mm/min without sometimes bogging down. And it uses much lighter aluminum plates.

    This is one reason why part of my upgrade consists of replacing the lead screws with rack & pinion.

    -D
     
  10. Steven Bloom

    Steven Bloom Veteran
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    What size are your nema motors ?? I might upgrade my motors as well to those 425 oz'er ones
     
  11. Jonathon Duerig

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    Currently, I have these on my lead screws: NEMA 23 Stepper Motor
    But the upgraded motors I got are these: NEMA 23 Stepper Motor - High Torque Series

    However, I know CNC router parts has these more powerful ones which I seriously considered:

    420 oz-in 3.0 mH NEMA 23 Stepper Motor, 3/8" Shaft | CNCRouterParts

    I'm mounting the CNC router parts 'pro' rack and pinion to C-Beams for my upgrade. I've got a final design that I've test-fitted using plastic plates that works well. And I should get some steel 'real' plates next week to actually build the thing and see how it works.

    -D
     
  12. Steven Bloom

    Steven Bloom Veteran
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    very cool. i have to be carefull if I change the Nema 23's. My current ones are 2A and my stepper drivers can only go to 3A, so if I upgrade motors, I may have to upgrade the steppers.
     
  13. Giarc

    Giarc Master
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    It is too bad you can't easily try the Acme 1/2"-10 5 start precision screws. I use 270 oz Nema 23s on a 1500mm by 850mm (roughly 49" by 26") cnc router build and I routinely cut plywood at 3000 mm/min. But, my build is all aluminum and I don't think my gantry could weigh much more than 25 pounds with the router (if that).
     
  14. Florian Bauereisen

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    HI
    i´m wondering about your psu, how much volts u are running?
    If 24 why not simply go to 48?
    I also support the opinion that the lead screw is binding.
    Use ball scews instead.These are build for cnc aplications. Having only a fraction of the friction u are seeing now. Plus they come in much bigger diameter, if wanted, which prevents whipping so you can up your speed further.
    Weight should not be a problem in a cnc at all. Mass dampens vibrations...
    ON my cnc the gantry weights 75 punds easy and it is moved b a single 2NM Servo (stepper wouldn´t change anything in this case). I get it to 7500 mm/min, wihle going slower (milling speeds) it would rip your arm of with ease.

    So all in all i guess you are facing binding /friction problems rather than weight problems.

    If you still decide to go the fiber route: please do not cut out your side plates like the stainless ones (open builds logo) cause you would cut the fiber strands.... leaving only the few on the sides intact....

    my opinion ...

    flo
     
  15. Steven Bloom

    Steven Bloom Veteran
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    It is too bad !!. But the whole thing uses the C-Beam and the parts that make that up. So that would be like scrapping the whole thing and throwing it out. That is a much more expensive option then me throwing $325 at it.
     
  16. Jonathon Duerig

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    If you wanted to try a larger size lead screw, you would need 2 sets of:

    1m (plus a bit) Lead Screw
    Nut Block (and possibly adapter to work with current plates)
    2 Bearings
    2 Spacers
    2 Lock Collars
    2 End Plates / Pillow Blocks
    Flexible Coupling

    Everything else would be the same, including the C-Beams.

    I bet you could get and/or make two sets of these for considerably less than $325. And it would likely yield a better chance of success.

    -D
     
  17. Steven Bloom

    Steven Bloom Veteran
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    finding a nut block that would work with my side plates would be a bear of an issue.. Plus there are two on each side. That would start getting expensive, those things can be $40 - $60 each.
     
  18. Rick 2.0

    Rick 2.0 OpenBuilds Team
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  19. Giarc

    Giarc Master
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    I made my own anti-backlash nuts out of Delrin using the cut-offs from the acme screw. I mounted them on the outside of the plates for the 1/2-10 5 start. I believe Dazthegas just did a similar modification milling adaptor plates for his ox. But again, even the $19 for the Delrin and the $81 for two 72 inch 1/2"-10 five start screws and $10 for 4 pillow block bearings is an expensive experiment. You would need new shaft couplers as well unless you had a friend that can turn the ends down. I was lucky enough to have that option.
    Ball screws may be the better option.
     
  20. Steven Bloom

    Steven Bloom Veteran
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    Here is a picture of the new plates. They are shipping them out today !!!

    DSC_0002.JPG

    DSC_0006.JPG
     

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