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Openbuilds 4x8 cnc

Discussion in 'CNC Mills/Routers' started by Sam Keller, Aug 14, 2020.

  1. Sam Keller

    Sam Keller Well-Known
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    So apparently I forgot to tighten and loctite one of the set screws on one of the z axis couplings. It came out and loosened up and one side dropped down half way thru a 12 hour carve and ruined my project. Lesson learned. It gouged several v wheels that I'm replacing today and going over the whole thing.
    20201103_110501.jpg
     
  2. chuck english

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    yikes.. Murphys law. it couldnt have done that on a 5 minute project. hate that for you Sam.
     
  3. chuck english

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    Hey Sam. Hope everything is going well. I'm still enjoying learning with the cnc. I'm just curious why you decided to go with belt driven x and y axis instead of an acme rod like the z axis?
     
  4. Sam Keller

    Sam Keller Well-Known
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    Hey Chuck, I looked into the screw thread and on the long axis I was hesitant on the length, I read of backlash and a limit of speed. I had dreams of running this pretty fast. On the short axis I couldn't figure a good way to mount the motor with the 2 z axis. I was counting on using the larger than my old cnc belts would be good enough but mine has skipped a couple times when I've pushed it too hard. I kind of wish I had looked into a rack and pinion, could have fastened a rack in the c channel and mounted the motor with a gear on the gantry cart somehow.
     
  5. Sam Keller

    Sam Keller Well-Known
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    I did get a laser on my machine and I like that allot. Still learning but there is allot you can do with them. 20201130_121747.jpg 20201130_204711.jpg 20201130_122244.jpg
     

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  6. chuck english

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    Very impressive. What kind of laser did you get? Is it difficult to change between it and the router. This is really interesting!
     
  7. Sam Keller

    Sam Keller Well-Known
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    I bought a Chinese diode laser off ebay, made a mounting plate that screws on to the gantry. It's easy to remove. I added an air assist made with cheap parts and an air pump. I think the Laser is only about 8w but i took it apart and it seems to be made well.

    20201203_142642.jpg 20201203_142701.jpg Capture+_2020-12-03-14-32-35.png
     
  8. chuck english

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    That is awesome! You're going to have to forgive my stupidity again, because I have questions.
    What exactly does the air assist do? and why do you need it? When you say air pump? Is this an air compressor? or is the air pressure much lower in your "air pump" than a shop air compressor? The plastic adjustable/flexible hose is what the air is going through? correct?
     
  9. JustinTime

    JustinTime Veteran
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    Sam, what do you do for the fume extraction since your machine does not looks like it's closed in?
     
  10. ljvb

    ljvb Well-Known
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    Air assist moves the smoke out of the way which can have an effect on the effectiveness of the laser during the cutting/engraving process.

    And yeah, you need to ventilate the area pretty well as while wood fumes are not necessarily toxic, any chemicals on the wood if any, or plastics or non natural materials will have toxic fumes..
     
  11. ljvb

    ljvb Well-Known
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    Sam is going all out.. I'm waiting for him to add a water jet to it :)
     
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    (; using a pressure washer (;

     
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  13. chuck english

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    Sam, I think I may have to copy this too.... what thickness wood will that laser cut through? Will it engrave into metals?
     
  14. Sam Keller

    Sam Keller Well-Known
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    Sorry I missed all these posts...

    1. I love the laser except my controller only supports vector mode and not photo mode. Laser mode in grbl 1.1 allows the controller to rapid scan a photo onto whatever your cutting on. I'm looking for a new controller now.
    2. It will cut 3mm wood with like 6 passes. It does a nice job cutting but is a little slow.
    20201130_204707.jpg
    3. I bought an air pump because I was tired of my noisy air compressor kicking on all the time.
    4. I have a small exhaust fan in my shop that gets the fumes out sort of... Some people run a hose near the laser to suck the fumes up, prob a good idea.
    5. The diode lasers only cut wood, paper, cardboard ect and will not engrave metal unless it has a coating then it will take the coating off. I saw a guy paint a knife, laser it then use an etching solution where the paint was removed with the laser, then removed all the paint and it was etched metal.
    6. The water jet is a great idea... :)
    7. Over all I really like the laser, I wish it was more powerful like a C02 laser but it makes really fine detail, you don't have to sand the edges*, opens up a whole new world of things you can make.

    20201130_122753.jpg
     
  15. chuck english

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    I was wondering if the laser like you have could burn a photographed image into wood. So, you are saying that the laser will, but your controller will not? Would it be possible with my setup (cpu and blackbox controller?) Also, are you still using fusion to design your creations or are you using something like lasergrbl or lightburn? I know I am full of questions, but I have a few more. The laser that is just like yours is out of stock it seems. Were there any others that you looked at that you would have gotten that are in the same price range?
    Thanks again for all the help!
     
  16. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    If you bought a quality laser diode module that accepts PWM (adjustable output power to do grayscale engravings)

    Try the trial of Lightburn: Lightburn
    Also see docs:software:lightburn [OpenBuilds Documentation]
     
  17. chuck english

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    Are there some (laser diodes) that are relatively inexpensive that you recommend?
     
  18. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Sam Keller likes this.
  19. Sam Keller

    Sam Keller Well-Known
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    I've been using lightburn and like it. It will work with your black box and yes you can engrave photos onto wood or painted ceramic tile, or painted canvass, I've seen some really cool stuff made with lightburn and a diode laser.
     
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  20. Sam Keller

    Sam Keller Well-Known
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    If you want inexpensive to start with there are a lot of smaller lasers that will engrave pictures in wood even the 2.5w. There are so many choices out there so maybe Google it, lots of good advise
    Capture+_2020-12-17-09-52-55.png
     
    #140 Sam Keller, Dec 17, 2020
    Last edited: Dec 17, 2020
  21. chuck english

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    Sam, the one that you bought and the ones you suggest have the PWM (adjustable output power to do grayscale engravings) that Peter is talking about?
    Thanks!
     
  22. Sam Keller

    Sam Keller Well-Known
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    Yes, buy one with PWM to control the laser power. Facebook has alot of laser and lightburn groups you should check out. This picture on wood was made with a 2.5w laser
    Capture+_2020-12-17-10-57-42.png
     
  23. Modou

    Modou New
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    Hello I am interested in this machine and I would like to know if you can help me with the purchase and installation.
    what is the total cost of the parts to begin with
    I'm in Senegal (West Africa) https://twitter.com/senfablab
     
  24. chuck english

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    Hey modu. I followed sam’s build and basically copied it exactly. The only big difference was I use a computer connected to black box controller (from open builds store) and he used a stand alone controller and external drivers/(I believe an arduino board). My costs I believe were around $2000 This does not include the computer as I already had it. Sam has a list of everything he ordered. Like he said there are a few things he ordered that are not necessary. I believe everything was ordered from either the open builds store, eBay or Amazon. Sam has lots of good pictures and much more insight than me, but I will be glad to help any way I can.
     
  25. andydoc

    andydoc New
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    Sam...looking at building a 4x8 myself and just came across this...awesome build! Wondering what types of feeds and speeds you can do with a 1/4 and/or 1/8" bit in things like MDF, Plywood, and solid wood like oak or pine? Looking to do some 3d carving on a larger scale...

    Thanks...AndyDoc
     
  26. chuck english

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    Andy, Like I said before we copied Sam’s build. We usually run 1/4” bit at 100”/min in mdf and plywood; usually with about 40-50% of the bit width set as step over and pass depth and haven’t had many issues. With 1/8” bit we have used at same speed and same settings, but we have had some some issues where the belt slips and the cut gets off. So, typically we run 1/8” a little slower.
    you want to do some 3D carvings? I am interested in this. All we have tried is 2d and we are very green to everything cnc routing. What are you using to design/manufacture your 3D designs? We are using fusion, but I haven’t played with 3D much at all.

    ps. We have cut some oak and pine with 1/4” bit at those settings with no issue as well.
     
  27. Sam Keller

    Sam Keller Well-Known
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    Andy, Chuck is right on the money for the speeds. The belts are defiantly the weakest link in this design. I do 3d carves at 80 ipm. I leveled my spoil board at 150 ipm just taking a skim coat off. It is nice being able to put a whole piece of plywood on it. I looked into a rack and pinion but that was too pricey for my taste.
     
  28. andydoc

    andydoc New
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    Thanks a bunch. A friend has this idea he wants a carved wooden door (something like this link). I've been running a Shapeoko2 since 2012 and upgraded it to ~20x20...but looking for something that could cut a full sheet. I use and LOVE Fusion360.



    would going to a larger belt help with the slip?
     
  29. Sam Keller

    Sam Keller Well-Known
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    So I've made some updates to my machine. I was having trouble with my large nema 23s stalling at high speed/torque and I thought it was belt slipping but it might have been the motors stalling. When i would try to move at 300 ipm and over 150 acceleration they would stall. I researched it and concluded that i need more volts. My external drivers can take up to 50v. I had an extra 24v power supply so i hooked 2 24v supplies together in series to provide 48v and it works great. I can move my x and y axis 800ipm with 5000 acceleration with no problems at all. This thing zips all over, not that i need to go that fast. I haven't cut wood with it yet but i think it will help.

    I also changed controllers to this grbl 32bit wifi controller. It's really flexible and it creates a wifi point that you connect to with your phone tablet orcomputer. Then it opens up grbl32 cnc controller and runs great. Lots of cool features.
    A New, Fully Modular CNC Controller at Buildlog.Net Blog

    A few months ago i had a set screw come out of my z axis coupling, it dropped my z and crashed my machine so i got new couplings, drilled and tapped 5mm threaded holes for larger set screw that i could tighten better.
    20210112_093910.jpg 20210112_093945.jpg
     
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  30. chuck english

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    Interesting. I am guessing the black box and it’s internal drivers won’t work at 48v? We actually never returned the external drivers like you have, but I haven’t wanted to take on the task of connecting them with an arduino. However, if you see that it is a huge benefit I would probably do it. As we have had issues of cuts getting off when you push the speeds.... (seems to be with smaller; bits don’t know why). I like you thought it was belt slipping....
     

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