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  1. #1
    Join Date
    Dec 2011
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    0

    cnc home build

    hi there, I have been scouring the huge amount of information about home building a cnc router and have reached a point where I don't know where to go. If there is someone out there that will talk to me about their own experiences so that I can make some headway.
    For example; should I go with rack and pinion or chain drive. From what I have seen I am leaning towards the rack.
    Should I do the skateboard bearings on aluminium angle or v-bearings...
    Has anyone looked at taking the sliding mechanism from a compound mitre saw and applying it to the Z axis?
    I hope that someone, or even a couple of people, may take the time to contact me and then maybe mentor me through this .

    cheers
    and regards
    rob

  2. #2
    Join Date
    Mar 2003
    Posts
    35538
    Rack and Pinion is far superior to chain drive.
    Any bearings on aluminum angle is a bad idea.

    Imo, the machines that use chain drive and V bearings on aluminum are slow, flexible, poor performing, and WAY overpriced.
    The most popular linear motion used today is probable the stuff from CNC router parts.
    CNCRouterParts

    As for the miter saw bearings, it's a lot easier to just buy a set of these for $99 and bolt them on. Glacern Machine Tools - Linear Rails and Bearings

    A lot of people just buy a ready made Z axis. K2 CNC Router - CNC machines.


    What size machine are you looking for?
    What do you want to do with it?
    What is your budget?
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  3. #3
    Join Date
    Jul 2008
    Posts
    390
    I have built a machine with skate bearings that rode on a steel channel. It was a hybrid between the skate-bearings-on-alu-angle and other skate bearing designs. Long story short, it was not a pleasant experience and some of the design choices that resulted were... regrettable. Overall, it wan't all that much cheaper than just buying used linear rails from eBay.

    Please do yourself a favor and don't muck around with skate bearing designs if you don't have to.

    By the way, listen to ger21. He's a pro.

  4. #4
    Join Date
    Dec 2011
    Posts
    0

    thanks

    and again ,thanks, for the response. I had tried to initiate a conversation in another forum and was told to suck it up and "just go build something" and learn from my mistakes. They also wanted to push their kits .... I kinda thought that it was better to see how other people had solved problems and learn from that. Extraordinarily as that seems, they suggested that was a damn fool idea. Kinda strange I thought.

    I was wanting to have a machine that had a working area of, say, "X" 4', and "Y" maybe 3' or 4', "Z" could be as little at 3" or 4" although I can see that some sort of major adjustment could shift that to a bigger range. I have seen a floating head arrangement that could achieve that.
    I am a woodworker, that can weld, and pretty much do anything. I have a fairly well equipped shop and the construction of the table is no problem. I am interested in computers and have an average amount of experience in that field.
    What started me in this exploration was a guy hosting Woodworking for engineers
    , he does pretty extraordinary stuff with wooden machines. I figured that with a cnc router I could do most of the tasks that he has developed dedicated machines for.
    I would like to be able to machine decorative brackets in wood and possibly aluminium, ceiling roses... 3d carving...fancy-dancy dovetail joints and a gazillion other things.

    I would like to achieve this with a budget of $2000ca.

    I am hoping that I can find a machine graveyard in Vancouver or Vancouver Island and rescue part, such as linear rails...

    cheers
    rob

  5. #5
    Join Date
    Apr 2009
    Posts
    5516
    I wouldn't totally discount the skate bearing idea. I had a lot of success when I built my first machine (and some failures but that's the fun of it) and still use them on the z axis of my latest machine.

    The CNC Router Parts carriages are essentially skate bearings that roll on cold rolled steel rails, and they're very affordably priced, as well as their rack and pinion setup. Hundreds if not thousands of users here.

    I probably wouldn't go with chain drive, as Gerry mentioned. It won't be easy to remove backlash, though it is cheap. They do make roller chain, as well as roller sprockets that ride on special track, but they're very expensive.

  6. #6
    Join Date
    Mar 2003
    Posts
    35538
    I had tried to initiate a conversation in another forum and was told to suck it up and "just go build something" and learn from my mistakes. They also wanted to push their kits .... I kinda thought that it was better to see how other people had solved problems and learn from that. Extraordinarily as that seems, they suggested that was a damn fool idea. Kinda strange I thought.
    I'm a member of that forum, and occasionally offer help there. However, imo the machines are garbage, and perform 1/10 as well as what you'll see here. They also cost a lot more money. The people building those machines don't seem to have any idea of what else is available today. 10 years ago, at 1/3 the price, those machines would have been "ok". But not today. They think homebuilt cnc machine's are slow, and not very rigid, and that just doesn't have to be the case today, as their are more good quality products for the home CNC hobbiest than ever before.

    Now, realistically, $2000 isn't going to get you a decent machine 3x4 machine.
    Since steel is cheap, and you can weld, you might be able to build one if you can design it yourself.
    Go to CNC Router Parts and look at their plans. They are usually built from aluminum extrusion, but you should be able to weld up a steel version for much less money.

    The simplest method, imo, is to weld up a frame, and use all linear rails from Glacern. A set of 1540mm for X, and 1240mm for Y, and the 340mm for Z.
    That's about $480.
    Using the CNC Routerparts carriages and CRS rails might be a little cheaper, but not much imo. The Glacerns will be smoother, and can just bolt right on. A much better approach imo.

    Get a 4 axis Gecko G540 electronics kit from Keling for $565

    Drive the X axis with 2 rack and pinion drive from CNCRP, about $300 with rack.

    Drive the Y and Z axis with 1/2-10 5 start acme, which you can do for $150-$200

    So that's about $1500, and you still need steel, and the misc stuff adds up quick. You'll definitley go over $2000, and probably be closer to $3000

    But, you might need to spend a few months here reading to be able to come up with a good design. This thread might be a good place to start, as it's built with a welded steel frame. http://www.cnczone.com/forums/cnc_wo...nc_router.html


    If $2000 is your limit, consider building a smaller machine from MDF, like the Joes 2006. He sells a somewhat pricey kit of parts, but you'll save about $400 if you can cut the parts yourself. Here's an excellent example of building accurate parts yourself using a router table and templates. http://www.cnczone.com/forums/joes_c...06_metric.html

    You should be able to build this machine yourself for right around $2000, imo. And, you can probably stretch it to about 30"x42", but I wouldn't go any bigger. Keep in mind that as it get's bigger, it costs more, and gets more complicated to build accurately.

    Feel free to ask any questions you have here. You'll get good, knowledgeable people giving you honest answers.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  7. #7
    Join Date
    Jan 2008
    Posts
    853
    Its funny, I was going to argue the merits of skates on Al, but just went out to clean up a bit after some intensive gift-making, which involved many hours of repetitive motion on the same section of X rail. And despite all of my efforts to make it run true, I can see quite severe scoring on one X rail of my Al angle track. I am going to try steel angle to avoid making major mods, but proper rails seem to be in my future.

    I have chains, and would argue that they are quite fast (1000 ipm rapids are easily done, and I can cut at 250 ipm), relatively easy to get going (no fussy alignment), but will not give a surface finish as precise as you will get with screws or R&P because of cogging. The ease of setup turns out to be a weakness : you can easily adjust the tension on each side, but how do you decide that it is just plain right? I am still dreaming of an Everman belt drive to get a better blend of speed and accuracy...
    Cheers!

  8. #8
    Join Date
    Dec 2011
    Posts
    0
    Thanks for your replies. I am very grateful to gain all this useful and well thought out advice. It has me far less confused that I was a few days ago.

    As far as my budget goes, I am happy to increase it since, with time, I can drift it up to where it needs to be.

    I shall spend a few days going over those parts you suggest Gerry and also take a look at other links provided.

    I was swamped with choices and it is so great to be directed to where I should be looking.

    cheers
    rob

  9. #9
    Join Date
    May 2007
    Posts
    86
    Gerry,

    I notice you recommend Glacern's...are they that much better than the chinese SBR20 rails found on ebay? They are 2-3 times the cost it looks like, so wondering if there is a huge difference?

    I have gone back and forth for my next machine on whether to do the CNCRP linear motion or go with a round rail solution. I'm building a smaller router, so the price will definitely be lower, just wondering your thoughts. I can get the ebay SBR20 for around the same price or even less than what the CNCRP system would cost.

    Thanks,
    Curtis

  10. #10
    Join Date
    Aug 2011
    Posts
    998
    Quote Originally Posted by piperpilot View Post
    Gerry,

    I notice you recommend Glacern's...are they that much better than the chinese SBR20 rails found on ebay? They are 2-3 times the cost it looks like, so wondering if there is a huge difference?
    I use the Glacern rails and they are good quality parts. However, they are from Taiwan that means kind of China, anyway. I don't know if the ones you order from China directly are really different. But just having the local distribution, lower shipping and the opportunity to return a set for longer ones made it worthwhile for me.

  11. #11
    Join Date
    Nov 2006
    Posts
    1036
    Quote Originally Posted by JerryBurks View Post
    I use the Glacern rails and they are good quality parts. However, they are from Taiwan that means kind of China, anyway. I don't know if the ones you order from China directly are really different. But just having the local distribution, lower shipping and the opportunity to return a set for longer ones made it worthwhile for me.
    I also bought Glacern rails for one axis on my small router. I too found them to be very high quality and was surprised by how well they were protected from shipping damage.

  12. #12
    Join Date
    Mar 2003
    Posts
    35538
    Gerry,

    I notice you recommend Glacern's...are they that much better than the chinese SBR20 rails found on ebay? They are 2-3 times the cost it looks like, so wondering if there is a huge difference?
    I've never used either, but can you give me a link to ones costing 1/2-1/3??
    Here's one set that's $10 cheaper, but they are smaller, 16mm vs Glacern's 20mm. Well worth the extra 10imo.

    A set of Glacern's similar to this set would also be $10 more.

    I'd gladly pay an extra $10 to avoid ordering direct from China.

    Now I did see this set that looks really cheap. But, add an extra $80 for shipping, and be aware that you're not getting what's in the picture, as the bearings are 3 different diameters.

    Comparing apples to apples, I don't see any advantage to buying direct from China.

    I have gone back and forth for my next machine on whether to do the CNCRP linear motion or go with a round rail solution. I'm building a smaller router, so the price will definitely be lower, just wondering your thoughts.
    My personal preference would be Hiwins from AutomationOverstock. A set of 15mm bearings for a 24"x24" machine would be around $500-$600.

    The bearing blocks are $3 more than CNC Routerparts smaller carriages, and the rails aren't that much. To me, for a small machine, the Hiwins would be a no brainer vs CNC Router Parts. As you go bigger, you'd want larger Hiwins, and the price would go up a bit. For my 48x72 router with 2 Z axis, I'm spending $1300-$1400 for Hiwins.

    Comparing Glacern to CNC Router Parts, it would appear that the Glacern's are much cheaper. But since I've not used either, I can't really make a recommendation.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  13. #13
    Join Date
    Feb 2011
    Posts
    270
    Hi Rob, Welcome to the forum. You might want to take a look at the PDF file I created which contains a lot of information, and drawings of my original machine design. It's actually stored on the Machsupport website at: My CNC build

  14. #14
    Join Date
    May 2007
    Posts
    86
    Gerry,

    Thanks for pointing out the High shipping charges on the ebay guys. I didn't notice that. I was looking at this one:

    2 linear bearing slide unit SBR20-800mm rails+4 blocks | eBay

    $59 for 800mm seemed awesome...but its also a $74 shipping charge which makes the total $133.

    Glacern doesn't have an 800mm to compare, they have a 640 for $129 and a 940 for $149 so split the difference and 800 would be $139. Shipping via UPS Ground is ~$20 so that takes us to about $169 or around $40 difference in price. Probably worth it for ordering from US and having a warranty.

    I haven't done a price comparison yet, but I did find this kit:

    3 SBR20 sets +3 ballscrews RM1605+3BK/BF12 +3 couplers | eBay

    Three sets of rails and 3 ball screws with all required hardware for ~$600 shipped. That seemed pretty reasonable considering the rails alone from Glacern are about $400 shipped.

    As usual, too many options at different price range/quality...makes the decision harder.

    Curtis

  15. #15
    Join Date
    Dec 2011
    Posts
    0
    take a look at the PDF file I created

    Thanks adprinter, I actually found it and have sent it to my work so I can print it and spend a useful day ;-)

  16. #16
    Join Date
    Mar 2005
    Posts
    266
    Some of the China sellers will take custom orders and combine shipping.

  17. #17
    Join Date
    Sep 2011
    Posts
    281
    I started building a CNCRP 4x4. I ordered the 8020 from faztek.ca here in Canada and the rest of the parts minus the electronics from CNCRP. Electronics I ordered from long_motors on ebay for the steppers and found a good deal on a G540. I wish I had spent the little extra and gotten some keling's or bit the bullet and just ordered the gecko drives. Differance would have been maybe 50-60. I think (looking around for prying eyes) I spent around $3000 altogether. Now that includes computer, monitor, buncha extra electronic crap, etc.

    I will probably end up purchasing a new set of motor's some time in the future which will cost me a set of pulley's. And I might end up upgrading to a toroid power supply instead of the switching one I currently have.

    Colten Edwards

  18. #18
    Join Date
    Dec 2011
    Posts
    0
    So, I continue to read and look and listen. There is one thing I was wondering about though. We want rigidity and NO backlash, amongst all the other things... Torsion boxes are often used in the wooden machines. On the table and on the Y axis. as yet i have not seen much in the way of similar on the vertical support for the Y axis. It seems to me that adding rigidity to that upright must improve overall performance? Even in lots of the steel or aluminium builds i look at, the vertical support, seems prone to flex. Am I missing something?

    Most builds seem to have the bearings, linear rails etc arranged vertically. Does it not make sense to have these rail systems horizontal, increasing the width of the Y axis supports?

    rob

  19. #19
    Join Date
    Mar 2003
    Posts
    35538
    Even in lots of the steel or aluminium builds i look at, the vertical support, seems prone to flex. Am I missing something?
    No, that area is very prone to flex, but most don't seem to build them as strong as they could.

    Bearings don't need to dictate the design. You can build it very strong and rigid regardless of the bearing orientation. Also consider that some types of bearings are better suited to a specific orientation.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  20. #20
    Join Date
    Dec 2011
    Posts
    0
    I went to look at a home built cnc router today. I found that a guy on the island had been involved with cnc for 6 years.
    What I found was the cnc router, and a plasma cutter, also home built, and a laser cutter. All huge.... It was inspiring.
    How does one get from here to there ?
    The cnc router was busy resurfacing the spoil board and with its spindle, normal conversation was easy.
    He then demonstrated the laser.....u n b e l i e v a b l e.... in one minute he had cut a miniature guitar with incredible detail. The tuning pegs must have been a zillionth of an inch dia. It was awe inspiring...
    Apparently the plasma cutter is for sale and will be replaced with a water jet cutter...egads... you know 40 thou kerf versus 20 thou kerf...

    Salt Spring CNC | Plasma Cutting, CNC Router Cutting hmmm...not sure that is a real link...
    anyway. Back to reading and looking

    cheers
    rob

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