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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > New machine build based on DamenCNC and RoboCNC designs...
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  1. #1
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    New machine build based on DamenCNC and RoboCNC designs...

    Greetings all!

    I am about a month into the design of a new CNC machine as my winter project. I didn't know anything about CNCs a month ago really, but being able to do research 8 hours a day for the last 4 weeks, and reading everything I can on here has given me at least an inkling. The goal of the project is a very stiff and accurate large format 4x8 (approximately) machine. I thought about purchasing an AVID CNC, but it was going to be several months before delivery, and with time on my hands, I decided to DIY. Last year I built an Overland truck that I used to visit 29 states and ended up at Overland Expo West. I didn't know anything about that before I started down that path either, so I'm familiar with being a newbie and soaking it in. This year, I'm a CNC noob. Haha!

    Design
    I'm basing it on a CNC design from DamenCNC in the Netherlands. You can find a similar build from RoboCNC on YouTube. I am taking their design that is built to be stiffer than a normal tall gantry design and making it even stiffer with additional bracings and larger extrusions. The base of the machine will be 80x160 with cross bracing, and the legs are all 80x80 with cross bracing and redundant joining approaches for stiffness. I'm attaching a PDF of my final design to this post.

    Mechanical Parts
    I will be using a number of pieces from Damen CNC including their minimal-backlash dual pinion R&P drives as well as their entire Z-Axis. I've also purchased all of their CNC'd parts for the drives and been working with them on all of the dimensions. I've now ordered all of the aluminum extrusion from my local T-Slots Rep (I got quotes from Parco, Item24, 8020, T-Slots, and Eagle.) Since I needed 8mm slots, Misumi was out. I ordered Hiwin Rails from Motion Constrained (who I can recommend wholeheartedly - they are awesome), and got my Rack from Damen.

    Electronics
    Now I'm at the electronics, servos and spindle/VFD part of the build. I'm debating whether to get something already built from Avid CNC, or roll my own with Centroid Acorn at the center. I'm speaking with Clearpath currently to figure out the right fit for one of their servos, but that gets REALLY pricey.

    I'm hoping to be able to ask a lot of questions about the build and the electronics. There is obviously a WEALTH of knowledge here. Currently I'm looking at steppers, CL steppers and servos trying to figure out which to go with. I've never done any wiring, but I'm game, and I love learning new skills, so I think I'll be okay with some good guidance.

    Anyway - just wanted to say hello instead of continuing to lurk in the dark. I appreciate all the great content here, and hope to share some trials and tribulations as I move forward!



    RoboCNC Design
    https://www.youtube.com/playlist?list=PLx3FKzVphd7cRb9nwFMyCkJLcRBChdojC.

    Damen CNC Minimal Backlash R&P
    https://www.damencnc.com/en/r-p-drive-antibacklash-diy-includes-gears15t/a554?search=R&P

    Damen CNC Design
    https://www.damencnc.com/en/dcnc-router-kit-2700x1790x200mm/a2464?c=346

    Damen CNC Z-Axis
    https://www.damencnc.com/en/dcnc-router-z-axis-ballscrew-r-350mm-diy/a2291?search=z-axis




  2. #2
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    Re: New machine build based on DamenCNC and RoboCNC designs...


  3. #3
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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Hi,
    if you budget will stand buying servos then do it, they are just SO much better than steppers.

    Clerapath servos are good quality and thev been designed to be simple to set up and thereby attract first time buyers, and they have done good job.....but they
    are expensive for what you get. Remember that Clearpath have cut IO to the bone and no mixed control modes, that how they achieve their
    apparent simplicity.

    For the same or less money you can get Delta and DMM (Taiwanese and Canadian, both manufactured in China respectively) but with much increased
    power, vastly more and better IO and a plethora of control modes. They are both good quality, with good documentation and after sales service at fair
    prices.

    There are even cheaper Chinese made servos which work well but their documentation and after sales service is crap. additionally they do not have
    any set-up or tuning software. Both Delta and DMM, and all the good servo manufacturers have software that you install on a PC and the PC
    programs the firmware of the drive. Modern AC servos have over 500 set-up and tuning parameters, set-up software is all but essential.
    The cheap Chinese servos are programmed by pushing buttons on the drive like programming a microwave....avoid like the plague!

    There is a lot of hype around closed loop steppers....and it is hype.....and very little truth to any of it. The manufacturers would have you believe that
    the 'closed loop' suddenly makes steppers faster, more powerful etc....BS, they are still steppers. If you are budget constrained LOW INDUCTANCE
    open loop steppers with the highest voltage drivers you can afford/find are the way to go. If you want closed loop performance go for servos, don't waste
    your money on Mr In-Between, aka closed loop steppers.

    Craig

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Great advice - thank you! I haven't spared any cost so far, and keep looking for places that I'm willing to, but as soon as I start working on something, I think "well, for just a little more money, I can do it.better", Unfortunately, that has compounded to a very expensive machine - haha! I have been looking at the DMMs, but was attracted to the simplicity of the Clearpath. It's good to understand that the simplicity comes with some compromises. I'll need to dig more into that before making a decision. I liked the idea of not having to wire up an additional driver per motor, since it's my first time wiring electronics this complex. I've built RC cars before and built very complex home theaters, but this is a completely different level!

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    I do not know if the Clearpaths are any less capable than DMMs or Deltas but check with Teknic. They have knowledgeable engineers here in the US that are very willing to answer any questions you might have. I have Clearpaths and their built quality seems to be very high.

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    I'm going to speaking with Ian from Clearpath on Monday. We had started an email correspondence on Friday, but ran out of time. I'm at a bit of a disadvantage when it comes to the advanced functionality of servos, but I can definitely take what he tells me and compare it to the DMMs.

  7. #7
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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Hi,

    do not know if the Clearpaths are any less capable than DMMs or Deltas but check with Teknic.
    Yes they are.
    1) Clearpath have one, just one digital feedback for error signalling called HLFB (High Level FeedBack). Delta on the other hand have eight (programmable) digital outputs,
    so you can handle Following Error differently and separately than voltage or current overload say. Delta have two analogue feedback outputs, so you can
    monitor speed and current say, or any of a number of analogue variables that could be assigned to either analogue output channel

    2) Clearpath has no encoder feedback channel. Delta does. You can program the Delta encoder output to have any line count per rev from 4 line to 4000 lin.
    This channel can be used to drive DROs say or can be used by the controller if for instance you have a feedback controller and you want to use analogue
    servo control., see anon

    3) Clearpath have, depending on model one of two 'lowish' (800 cpr or 6400 cpr) resolution primary encoders whereas even the entry level Delta model has a 160,000 count per
    rev encoder.

    4) Clearpath has step/direction (enacted alternately as step/dir, CW/CCW,or quadrature)only. Delta has both step/direction (enacted as step/dir, CW/CCW or quadrature)
    and analogue (+-10V). Delta has mixed control modes. Thus in primary mode it may be analogue speed control, for a spindle say, but in secondary mode (selected by activation
    of one digital input) step/direction. This allows the servo to be a free running spindle and then, at need, be a step/direction coordinated C axis for rigid tapping for example and the
    mode can be swapped back and forth at will and on the fly.

    5 Cost

    https://www.teknic.com/model-info/CP..._voltage=75VDC
    400W, or near enough to for $517USD

    https://www.fasttobuy.com/flange-80m...er_p28084.html
    750W, so nearly double the power and for less, $438USD

    I don not suggest that Delta is unique among servos, all the good servo manufacturers have a very similar suite of features. Delta and DMM are just very competitively priced
    examples of modern AC servo design.

    If you ask Teknics they will tell you they are the best......what would you expect them to do? It must be said, and to Teknics credit, that they have an active marketing department and have
    very good after sales service, no questions.....but at what cost?

    Craig

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Most of that is way above my head, but you're obviously passionate about DMM – I'll take a look. I'm not sure how much the encoder feedback channel matters if I'm using a Centroid Acorn, as it sounds like the Acorn can't take advantage of it, so some of that is maybe for more advanced systems. I'm also not going to be any rigid tapping, mostly working with wood. The resolution difference is definitely interesting for sure.

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Hi,

    but you're obviously passionate about DMM – I'll take a look.
    I have Delta servos, good quality and performance at fair prices, not bargain basement prices to be sure but good prices none the less.

    You are correct, there is probably no need at the moment for encoder feedback output channel, which is good because with Clearpath you don't have it whereas
    with Delta and DMM its there should you ever want it.

    As I posted earlier most modern AC servos have features much like I have outlined, if one manufacturer does something new and useful then all copy it.
    It means that a servo is very flexible and can therefore be used in the widest possible manner thereby including the largest possible customer base.

    For example, one of the control modes is 'torque mode' where a servo maintains controlled torque irrespective (almost!) of speed. This is very useful in conveyor,
    printing, and winding applications.

    It is unlikely that you will want that ability....and in fact that is what Clearpath has bargained on....you want a bog standard CNC servo and they have 'cut down'
    the usual suite of features to match your requirement but increased the price!!

    Its not so much that I am passionate about Delta but rather I'm passionate about not paying more than is required for good performance.

    Craig

  10. #10
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    Re: New machine build based on DamenCNC and RoboCNC designs...

    We worked with Newfangled Solutions and KINGSTAR, built this new CNC EtherCAT Motion Control System. It is fully Pre-wired, tested and configured with Computer. So you do not need any Breakout Board, Ethernet Board. You do not need to wire any more

    EtherCAT Servo Motor Control System with Mach4,750W, 3 Axis , it is very easy to connect , work great

    https://www.automationtechnologiesin...h4-750w-3-axis

    https://www.youtube.com/watch?v=IRNF...ature=youtu.be

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    I will say be aware of the shipping costs with FASTOBY if you go that route... its almost an additional $200 to ship to the US for 3 750w. The total does end up being around the same vs the DMM tech servos with 3 of their 750w servos and drives and cables (about $1500).

    I am currently researching servo systems for a knee mill retrofit I'm doing and kinda came to the conclusion that the Clearpath would end up being more expensive and less powerful than either the DMM or Delta setups.

    If you are going the Acorn route (I am) Marty has some really good YouTube videos on setting up the DMM servos with acorn.

  12. #12
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    Re: New machine build based on DamenCNC and RoboCNC designs...

    I ran across those videos - looks like he has quite a bit of good content on the Acorn - and I saw his video specifically on the DMM today.

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Hi,
    I bought a 400W Delta B2 series servo kit from FastToBuy off Ebay and they kindly offered free shipping, the same deal they offer US customers. I experimented with it and was impressed.
    It was to end up in my mini-mill but instead I sold to to my boss and we made a speedometer calibrator out of it, they are so versatile.

    When I came to buy three servos (one braked) for my new build mill I went back to FastToBuy. They gave me a sharp price for the three servos but I had to pay extra for shipping.
    FastToBuy charged me $80 for each of three servo kits for shipping to New Zealand, but that was DHL. I tracked it from Schenzen to my place of work in New Zealand in 2 days and 14 hours.
    I consider that I got what I paid for and am happy.

    Getting Clearpaths to New Zealand from the US would be at least as much. Likewise getting DMMs to New Zealand from Canada wouldn't be cheap either.

    For US based buyers DMM probably have the inside running for price including shipping per Watt.

    I have attached some pics of my new build. I have the cast iron beds back from being machined and now I am making the ballnut yokes, ballscrew mounts and saddle plates.
    As you can see I have the X axis ballscrew and linear rails mounted. Likewise the Yaxis has rails and ballscrew mounted. The Z axis is just the cast iron bed and the saddle plates
    are going to be ground flat tomorrow.

    With rigid machine components like this your accuracy, squareness, parallelism and alignment are critical, the smallest deviation causes drag. So I'll spend a few days grinding, scraping
    and shimming before I'm happy. Feels good to be making progress, the cast iron beds were out for machining for a long time.

    Craig

    PS Just as a note the axis beds are 750mm long, 250mm wide. The saddle plates are 270mm square.

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    So I spoke with Ian at Teknic today, and after giving him all of the specs for my build he was able to run a simulator on it. To my surprise, he suggested one of their smaller Nema 34 servos. I had been looking at their large "HP" ones for around $680, but the one he suggested was around $380 - and "SK" model - the 3411P-ELN (an enhanced one with a higher resolution). It will get me to around 980 ipm for rapids, and will have the torque that I need for my wood projects. I asked him what the next step up would be to account for the "I just want to be SURE to have enough power" coefficient, and he suggested the 3421P-ELN. At $405, it was still less than I had thought I would have to spend. And, since I won't need a separate driver and encoder, it's definitely easier for me to wire. I think is a good choice for a newbie who wants to run Acorn. So two IPC-5 power supplies, their wiring, and the servos. It's a big bite, but I think this is the direction that I'll go.

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Hi,
    that model (3421P-ELN) is 350W continuous. For nearly the same money, excluding shipping, you can have a 750W Delta B2 series with a 160,000 cpr encoder.
    The Delta (or DMM) have a separate driver, but two cables plug in direct between servo and drive, no wiring required, and the Delta drivers (and high voltage model DMM driver)
    are 230VAC input, that is you don't require a separate power supply as is required for Clearpath.

    As I posted earlier you can get double the power for about the same money.....you do the maths.

    Craig

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Thank you Joe - you've made your point, and I appreciate it.

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    I have a set of the smallest Nema23 Clearpaths on my "DavidA's desktop" project. The servos cost me about $280 each. I did have some problems utilizing the high level feed back output and four (!) Teknic engineers guided me through the problem. They still contact me even today to make sure everything is OK. Servos are very nicely built and smooth and they are totally adequate for a 2x3 desktop in my opinion. As documented on my thread, their power was enough to cut through 3/4 baltic birch and 1/8 aluminum in a single pass. I don't have 980ipm rapids but nice cuts where it counts.

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Quote Originally Posted by davida1234 View Post
    I have a set of the smallest Nema23 Clearpaths on my "DavidA's desktop" project. The servos cost me about $280 each. I did have some problems utilizing the high level feed back output and four (!) Teknic engineers guided me through the problem. They still contact me even today to make sure everything is OK. Servos are very nicely built and smooth and they are totally adequate for a 2x3 desktop in my opinion. As documented on my thread, they were adequate to cut 3/4 baltic birch and 1/8 aluminum in single passes. I don't have 980ipm rapids but nice cuts where it counts.
    Good to know, David. I spent some time on the phone with one of their support members today, and got the feeling that I would be able to get the support I need. I might not need the rapids, but on a 4x9-ish table (1500mm x 2960mm) it sure will be nice for getting to home and moving about the table for setup. Glad to hear that you're enjoying yours. I'm going to go check out your thread!

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Just caught my eye.....

    Is there a reason you don't pull up the legs to the bottom of top rail? I think it would be more rigid than a butt joint with bolted gussets.

    Click image for larger version. 

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    Re: New machine build based on DamenCNC and RoboCNC designs...

    Ah - it's an interesting idea. The one thing you can't see is actually the 400 Item24 automatic fasteners on the ends of the pieces of aluminum holding everything together. The gussets and joining plates are actually additional redundant structure that are unnecessary according to the original designers). I tend to overbuild everything I do, and I'm trying to make it as stiff as possible with aluminum. The original design called for 80x80 on the bottom stack of the machine, but I replaced it with 80x160, and shortened the vertical rails in order to strengthen that part.. Possibly, another reason might be that, at least to me, it seems easier to have a break with a "machine on base" configuration from a dialing-in standpoint. I am only dealing with the machine on top and not having to fiddle with the overall structure as I would if the legs reached all the way to the top.

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