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  1. #21
    so when i come to order my screws from chai.. if i ask for bk blocks they are 100% the ones i'm gonna get? the second ones u linked?

  2. #22
    Hmm before going to his shop I would of assumed so, but now looking at this: 3 SBR16 set+3 ballscrews RM1605+3 BK/BF12 +3 couplering | eBay Im not so sure.

    Id suggest either wait for someone who has ordered from chai to post, or email chai direct and explain what you need. Im in this process at the moment and he is nothing but helpful.
    Hobgoblin.

  3. #23
    ok i "think" i've finished designing the z? axis i've included a picture with 2 views, what i'm looking for is constructive ideas, so far everything is steel i think although some of the plated bits might end up being aluminium i would rather weld everything than tapping steel/alu.

    the small rectangle box sections are 50mm x 25mm and there is acctually only 2 pieces of 50mm square in there but these could also end up being 2 pieces of 50x25 slapped together depending on cost. the plates are all 10mm steel although the mount for the BK bearing is drawn at 5mm i'll edit that later.

    this has 100mm travel which i am hoping will be enough it is a 15" x 15" machine afterall so is intended to be small work pieces.

    so questions to anyone who can help before i progress further. does it all look like it will function.. i.e have i connected all the right parts in the right ways? a simple question to ask but i did originally put the ballscrew blocks on the same side as the rails.

    secondly as i am intending to make this out of steel is there going to be alot/too much weight on a 16mm screw and rails on either y or z axis?

    i can provide sizes of everything so far and if someone can tell me the weight of a piece of 50 x 25 steel box section i could work out the weight of everything.

    Click image for larger version. 

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    also if you would like a better view of anything let me know

  4. #24
    before anyone gets to pointing it out, i've just realised the bearing blocks on the rails are over hanging the 50 x 25mm box depending on what you guys think i might just replace the box section with 10-15mm alu as the next size up box section would have to be 80x40mm iirc and this will push the router further away from the y axis which is something i am concerned about

  5. #25
    Hi Wilfy,

    Has requested cast my eye.!!

    For an all steel structure it looks Ok thou I would replace the 50x50 with 50x25 to bring whole thing closer to Y axis plus gain 25mm travel.

    The back plate which fastens to Y axis needs some cross bracing, just relying on the top bot plates won't be enough. Also Because your using steel this z axis will resonate quite a bit more than an Ali Z-axis would. So it would be wise to attach motor to ballscrew with a timing belt to eliminate any resonance problems, I would consider running that top plate back between the Y axis uprights so the motor is at the rear.
    The 10mm plate is a bit OTT and 5/6mm would be fine strength wise and infact better if you take the route I've just suggested has 10mm is too thick because it shortens the motor shaft protrusion to much.

    Regards weight then it won't be a problem for the screw it's the motor that you use that will take the stress but a 3nm will easily handle it.
    3mm wall 50x25 weighs 3Kg/per Mtr

    If you can use Alu then I would has it handles resonance better but what you have drawn will work fine.

  6. #26
    the reason for using 50x50 was to allow spacing for the ballscrew and it's bearings but i'll re-think to try and bring it close.. plus using all 50x25 will be a bonus.

    i had planned to use timing belts so i'm glad we are on the same page there.



    the back plate which fastens to the y axis i am acctually considering using alu or steel plate in place of the box section as wont be able to use 50x25 box in the way i have in the drawings as the bearing blocks are 60mm wide with the holes at exactly 50mm spacing so i need to consider either 10mm alu or 6mm steel are both of these stiff enough if i'm using a piece of 370 x 170 plate?

    and thank you for your input so far it's nice to have your mind put as ease especially considering i'm adapting other peoples ideas but realisticly drawing this blind

  7. #27
    D.C.'s Avatar
    Lives in Birmingham, United Kingdom. Last Activity: 05-01-2016 Has been a member for 4-5 years. Has a total post count of 326. Received thanks 30 times, giving thanks to others 24 times.
    If you are buying steel, these guys seem to be having a sale on at the moment, they also list the weight per metre wilfy:

    100mm x 50mm x 3mm Mild Steel Rectangular Box Section - 1051216-1m

  8. #28
    Wouldn't want to be paying their normal price, even their sale price seems expensive to me.

  9. #29
    Quote Originally Posted by D.C. View Post
    If you are buying steel, these guys seem to be having a sale on at the moment, they also list the weight per metre wilfy:

    100mm x 50mm x 3mm Mild Steel Rectangular Box Section - 1051216-1m

    you my friend are a star :D i've bookmarked them for future reference.



    after the great advice from jazz earlier i've set about re-designing and i acctually feel much better about the one and it should bring everything close to rails aswell as giving me less work

    Click image for larger version. 

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    the green is the front where the router is bolted to, i aint had time to put that in but wanted to make this post before i go bed. it is just 50x25mm box with a 5mm steel plate on the front it's opaque so u can see the bearings underneath

    the 2 rear views are my current options... due to the bearings being 60 and 62mm wide i need to either use 60x40mm box x 3 the total here is 900mm over the 3 pieces which using a rough math from jazz's earlier post i get them 3 piece at 4-5kg total or i could use a big 15?20? mm slab of alu as per the 3rd picture.. this will bring the design 20mm closer to the Y rails but more crucially it'll weigh a hell of alot less...

    i would rather stick with steel as this is going to save me alot of money a rough guess see's the piece of the alu at 30 and the steel around 10 and thats before i go to a supplier with a full order with the hope of a price reduction... does anyone have any good reason why i should choose the alu over the steel?

  10. #30
    D.C.'s Avatar
    Lives in Birmingham, United Kingdom. Last Activity: 05-01-2016 Has been a member for 4-5 years. Has a total post count of 326. Received thanks 30 times, giving thanks to others 24 times.
    Quote Originally Posted by martin54 View Post
    Wouldn't want to be paying their normal price, even their sale price seems expensive to me.
    Really? I thought that was a pretty decent price. :(

    Where are you getting yours from?

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