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  1. #1
    update in orange

    ------------------------------- Update design (more detail in the discussion)
    Click image for larger version. 

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    Modification from the initial design :
    - Widening the table : 670mm > 800mm
    - The table will finally be aluminum > (160x80 + 40x80), I keep a steel base
    - Reduction of the steel profil section 100x100x5 > 80x80x5 for the base
    - Base is cut in several parts
    - Thickness of the gantry side plate : Aluminium 20mm -> 15mm (advice from Jazz in #5)
    - HGW carriage on X and Y axis (advice from Jazz in #2)
    - Ribs of the Z movable part is now turn on the Z fixes plate (more clearance around the spindle)
    - Clearance between Z carriage 107mm > 170mm (advice from Jazz in #2)
    - Clearance between X carriage 245mm -> 295mm
    - Height of the gantry 360mm -> 400mm
    - Indirect transmission on all ball screw 2:1 or 3:1


    ------------------------------- Description of the projet and Initial design
    Hi Everbody,
    After reading a lot and a lot of thread ! It is time to share my project ... I am a woodworker hobbyist and the machine will be 80% intended for wood panel and hardwood (occasionally aluminium if the machine could handle it). So the precision target is about 1/10 to 3/10mm and free speed likely 10m/min. The machine need to be taken to piece to go through a door and the elements could be carry without machine. I would like to use the table of the machine as workbench when it is not used for this reason I am not going on a canyon type of machine.

    Here are some pictures and detail on the present version :

    Click image for larger version. 

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    Here are some of my concerns :

    1. My TIG welder is 30% at 150A so 5mm of steel is probably the thicker width it could handle so I choose 100X100X5mm thick steel profil.
    2. Probable need to put extra plate in the 100x100 X profil to have more steel thickness for bolting the rail ?
      Bed and structure are independant part that are bolted together through a 100x100 cube spacing. I am not used to weld sutch structure but I thing that the distortion is not really an issue the support and will be corrected by West System resin epoxy for the bed. What you opinion on that point, do you recommend to cut the structure in smallest part and use bolt ?
    3. I am planning to use WestSystem resin to set my X axis on the same plane and the bed at the same time, need approx 2L (see pitcture). In France I don’t find small West System pack than 5kg 105 + 1.4kg 109 (270euros).
    4. What are the essential measurement tools i think i will place an order soon. (I already bought a rule of 1m class 0)
    5. Some doubts on the ball screw diameters : 25 or 32mm ball screw 10mm pitch for the X, 20mm or 25mm ball screw 10mm pitch for the Y and 16mm ball screw 5mm pitch for the Z
    6. HGH20 or HGH25 on the X (or HGW)
    7. Could I have racking issue with an only central ball screw ?
    8. General opinion on the design and if the machine I correctly balanced ? Weakness point ?


    Thanks for comments
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Gustave; 10-05-2020 at 05:41 PM. Reason: Add a picture of the update design in the first post

  2. #2
    Hello Gustave and Welcome,

    I've got a few suggestions that might help you.

    #1 Don't waste money and time epoxying the whole bed it's not required, Just do the rails. You will 99.9% of the time have a spoil board on the machine which you will surface flat and parallel. So all you need is a baseboard that is flat, uniform in thickness, and stable ie: Not MDF.

    If you are using Tig welder then distortion from heat will be much lower than Mig and you can control movement better. Take your time and move around so heat is spread around the frame.

    #2 Use HGW on X & Y as they provide more stability. I would even use them on the Z-axis but I realize you are trying to keep the width to a minimum. 20mm rails will be fine on all axis.

    ( you mentioned HGR as though it was a bearing, HGR is the rail, HGH and HGW are bearing types.)

    #3 The Z-axis bearings are spaced a little too close together and I would spread them out a little to improve stability. Even if this meant increasing the rail and rear plate length.

    #4 Go with 25mm ball Screws for the long axis but use 25mm pitch not 10mm with a 2:1 ratio. This will half the screw speed and reduce any chance of whip. With the ratio, It will give the equivalent of 12.5mm pitch so a little higher feed rate but much lower screw speed.

    20mm Screw with 20mm pitch with 2:1 for the Gantry axis. I know you have drawn it directly coupled but I would change that to belt drive for a few reasons.
    It allows for the ratio to half the screw speed and it lowers resonance greatly which helps the stepper motors run much smoother. It also helps with servo's for similar reasons too but not to the same degree.

    You didn't mention the motors your using, but if Servo's with 3000 Rpm then you may want to use a 3:1 ratio.

    #5 Use Fixed BK bearings on Both ends of the Long screw as they offer a little more stiffness.

    #6 You won't have any issues with racking at this width with this design unless you want to take very heavy cuts at the outer edges and even then it won't stall the machine, at worst you get a little deflection which doesn't really matter when roughing or hogging out material.

    #7 Lastly, Buy a good large Square. This will help you set up the Gantry and Z-axis. My preference is a Granite triangle.
    Don't stress over trying to achieve 0.001 precision for a wood router because it's just wasted as the material will move more than that. So what I'm saying is don't be paying Big money for precision instruments that you will never take full advantage of.

    Hope this helps and good luck.

  3. #3
    Hello Dean, thank you for this detailed and fast reply
    #1 In France the smaller 209 hardener I could find is 1.45kg … any advice for another product that I could find in smaller quantity in france ?
    150a for 5mm thick it is enough ?
    #2 I will go on HGW (X and Y) carriage and 20mm rails, I am in contact with Fred, do you recommend the Hiwin instead of BST trade ?
    #3 I will spread the Z carriage, the actual distance is 107mm. Could you give me a recommendation ?
    #4 Do the resonance also occur with servos motor ? I have chosen direct drive to simplify the build and also read that good pulley system could be expensive and this assembly could introduce backslash.
    25mm and 20mm pitch are uncommon no ? I think the max I found in the forum is 10mm. With such pitch associated with pulley reduction, do you think I could occasionally mill alu with enough precision ?
    For the Z I keep 5mm pitch ?
    I already bought a CSMIO IP-S and will probably go on servos.
    #6 The clearance between the X carriage is 250mm, is it enough ?
    #7 Could you advise a dimension of square ? I search “granit square”, it seem to be a very expensive
    Last edited by Gustave; 02-05-2020 at 09:14 PM.

  4. #4
    Hi,
    I have to change the design, the 100x100x5 base is more than 170kg (white parts on the skecth). I need to cut in several parts that to make the transport possible. I am thinking on where to cut and how assemble...
    I am also thinking on making the two side plate of the gantry in steel instead of 20mm aluminium to limit the cost. Have you an opinion on that ? What the minimal thickness to be equivalent to 20mm alu ?
    Last edited by Gustave; 10-05-2020 at 08:09 AM.

  5. #5
    Quote Originally Posted by Gustave View Post
    I am also thinking on making the two side plate of the gantry in steel instead of 20mm aluminium to limit the cost. Have you an opinion on that ? What the minimal thickness to be equivalent to 20mm alu ?

    Best regards
    I wouldn't go less than 10mm in steel thou in theory 6mm would do the job as it's only for the cross brace but it's the resonance why I would use 10mm, unless you braced it up with a few Vertical strips.
    To be honest I would use 15mm aluminum plate not 20mm for that part. Again could even get away with a 10mm aluminum plate but I wouldn't for resonance reasons.
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  6. #6
    Hi,
    Here are some update on the design :
    1+ 670mm width of the table -> 800mm
    2+ steel bed -> 160x80 + 40x80 aluminium profil (270e for WS 105+207 is the price of the 80x160 alu profil…)
    3+ the machine is placed on the steel base
    4+ 100x100x5 -> 80x80x5 for the base
    5+ base is cut in several parts
    6+ thickness of the gantry side plate : Aluminium 20mm -> 15mm
    7+ HGW carriage on X and Y axis
    8+ side of the Z movable part is now turn on the Z fixes plate (more clearance around the spindle)
    9+ clearance between Z carriage 107mm -> 170mm
    10+ clearance between X carriage 245mm -> 295mm
    11+ height of the gantry 360mm -> 400mm
    12+ indirect transmission on all ball screw 2:1 or 3:1

    Click image for larger version. 

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    Questions :
    #1: 25mm pitch ballscrew are very expensive (only french supplier or TBI) Fred don't have so for the moment I keep 10mm pitch. I can go on 32mm to increase max rpm of the Ballscrew (not so expensive upgrade) ?
    #2: what do you think of the following servos motors sizing 400w for the Z with brake, 400W for Y and 750W for X ?
    #3: recommandation for "low cost" and CSMIO IP-S well documented or easy wire servos driver
    #4: central ball screw is still relevant with the slight increase of the width ?
    Last edited by Gustave; 10-05-2020 at 07:54 AM.

  7. #7
    #1 Have you asked Fred about 2525 balls crews because I've had them from him and he's advertising them on his site.?

    #2 Those sizes will be fine.

    #3 Wiring is no different for any servo, they all pretty much wired the same way. The servo tuning is most important but unfortunately Low cost and simple auto-tuning drives don't really go hand in hand. If you want easy tuning then you need drives which autotune and these tend to cost more. Look For Delta B series drives which are supposed to be good auto-tuning drives.

    Why do you want Servos.?

    #4 No, now with 800mm you have gone into 2 ball screw territory. The single screw will work but you will have to reduce the DOC/Feed at the outer edges.
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  8. #8
    #1 Wrong statement! I ask Fred for 2520 not 2525 (BST and TBI brand). It was after a call with a technician from Hiwin that recommend to go for 10 eventually 20 pitch but described the 25mm used for fast transport and no milling operation. From this own, 25pitch is less rigid and need to go with larger diameter than 10pitch so I ask for 10 and 20mm...

    #3 I already made the expense of an IP-S 3MHz so using servos could be coherent... Perhaps I am too confident with CSLab manual but understand that they only cons are a bit pricy like 2X stepper price if bought directly in china (if AC220v it don't have expense for power supply no ?) and perhaps tricky to tune. Pros : silence, smooth, high torque with increase of speed, no or cheap power supply... do you think it is overkill ?

    #4 Even if I have increase X carriage space up to 300mm ? I love the idea that ball screw is protected under the table. I my workshop often carry long wood piece that could hurt the ball screw if I wrongdoing ... Do you have some photos of you double ball screw integration, you keep them under the table, do you conserve the under table Y bar, you use one motor per ballscrew or use pulley system ?... Sorry, I have so much question !

  9. #9
    Quote Originally Posted by Gustave View Post
    #1 Wrong statement! I ask Fred for 2520 not 2525 (BST and TBI brand). It was after a call with a technician from Hiwin that recommend to go for 10 eventually 20 pitch but described the 25mm used for fast transport and no milling operation. From this own, 25pitch is less rigid and need to go with larger diameter than 10pitch so I ask for 10 and 20mm...

    Ok, I understand now. What the Hi-win tech probably didn't now was the 25mm pitch screw is a multi-start thread so the diameter is maximized. They won't be any less ridged than the 10mm.

    #3 I already made the expense of an IP-S 3MHz so using servos could be coherent... Perhaps I am too confident with CSLab manual but understand that they only cons are a bit pricy like 2X stepper price if bought directly in china (if AC220v it don't have expense for power supply no ?) and perhaps tricky to tune. Pros : silence, smooth, high torque with increase of speed, no or cheap power supply... do you think it is overkill ?

    Ok but IMO for a Hobby Router they are OTT and far more complex, esp if using the Cheap Chinese Servo's. They also require your whole electrical and wiring system is top notch so they don't get affected by electrical noise etc.
    You probably won't use the extra speed they allow and the noise from the motor is immaterial compared to the noise from cutting.!

    The smoothness is positive that Steppers cannot match and the resolution they cannot match either. However, Closed-loop steppers still provide more than enough resolution than is needed for most router type operations. Even on Aluminium, they are ok because the Resolution won't be the weak link in this material and the machine is only good as the weakest link.

    You can get Closed-loop drives that use Mains power so you don't need a transformer.

    My advice is that if your prepared to battle with Motor Tuning and take the care required on the electrical side then go with Servo's because there is no doubt they are superior to Steppers. However, that doesn't always mean they are the best for a given application and user.?

    If you want Simple, easy to set up and super reliable with less resolution but still with more than you probably require and with a slightly less smooth operation then go with Closed-loop steppers.

    My Choice for a router this size and for Home/small business use would be Closed-loop steppers.

    #4 Even if I have increase X carriage space up to 300mm ? I love the idea that ball screw is protected under the table. I my workshop often carry long wood piece that could hurt the ball screw if I wrongdoing ... Do you have some photos of you double ball screw integration, you keep them under the table, do you conserve the under table Y bar, you use one motor per ballscrew or use pulley system ?... Sorry, I have so much question !
    Extra length carriage would help but you are still on the edge. You can still have the screws under the table, my design you copied from uses twin screws. Either connected with belts or twin motors, I've done both. However, there are some things I'm not prepared to disclose so sorry no pictures.!!
    -use common sense, if you lack it, there is no software to help that.

    Email: [email protected]

    Web site: www.jazzcnc.co.uk

  10. #10
    Do you have example of closer loop stepper that use main power ?
    I will work on twin ball screw version... Thank you

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