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  1. #21
    The bearing blocks look too close together in the vertical direction to me.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  2. #22
    Hey JazzCNC thanks very much indeed for that it sounds like I'm on the right track now, I did think about top and bottom but thought this might split the forces between up and down and back and forwards although doing it this way I guess the loads are on a single rail more for each movement. So will do I will go top and bottom which will be great to get rid of some of the material around the back. I didn't really want it there but it was the only way I could think off to get the rail around the rear to also try and keep it out of harms way too.

    I am really sorry when you say move the rails back do you mean so that the spindle is inline with the upright box section of the gantry ? would it maybe worth going for something like 100x50mm box section for the sides and then put the 50x50 towards the rear to the spindle so it is more inline with the uprights of the gantry, I'm sorry if I've misunderstood.
    Also on a side note I would like to thanks you very much for helping so many people on this community I have learned so much from you going through many peoples posts and its great to see people just trying to help each other out.

    Also EddyCurrent the same goes for you going through peoples posts you are very helpful I just hope that I can get a machine running to be able to get the knowledge to put something back in.
    Don't worry I'm not always a soppy sod.
    I thought I might have the blocks a little too close but just picked the figure out of the air really for the distance. Is there an optimum or a way of determining the best gap ?. like most I was trying to maximize the cutting depth but because the bed moves I will add some more distance on it and just move the bed on each time I have a thought to making some fiberglass molds with foam for a dash board and though the more depth the better but I guess it will give a worse cut for other things I will have another go at it and go more in depth on the design now I know where I'm going with it all.

    thanks chaps.

    Rob

  3. #23
    Quote Originally Posted by grain_r View Post
    I am really sorry when you say move the rails back do you mean so that the spindle is inline with the upright box section of the gantry ? would it maybe worth going for something like 100x50mm box section for the sides and then put the 50x50 towards the rear to the spindle so it is more inline with the uprights of the gantry, I'm sorry if I've misunderstood.
    No was meaning offset back something like this for better centre of gravity and balanced bearing loads while cutting.Click image for larger version. 

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    Regards bearing distance then I work on Half the travel required.!
    Last edited by JAZZCNC; 17-10-2014 at 04:57 PM.

  4. #24
    Oh I see. great thanks I like that. So that I might save a little welding heat is there anything to stop me mounting the screw on the base of the box section although It won't be in the centre or is it best to put some uprights in and then mount to that ?

    Thanks
    Rob

  5. #25
    I have been working on the updates and getting there now because I intend to make it my build log I thought I would keep updating with work in progress for my designs so people can see for the future . I'm getting pretty happy with the design now it seems to feel much better and thanks to you guys I am learning so much with each design change.

    I am having a problem with the X axis I want to use one motor as people have suggested in the past because of Binding and using belts but I cant think of an easy way without using quite a few wheels to send it around the frame if I go directly across It would hinder the work pieces if they hang over the edge.



    Any comments would be most welcome. I havn't put the cable trays or the front axis as yet thats being done at the moment.

    Thanks

    Rob
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  6. #26
    I know it's a bit more expense but why don't you make the Y axis rails longer and have the bearings spaced further apart on the top and botom rails? It would give you a stiffer machine and looks like the space isn't needed for cuting as you're rails are shorter than the Y axis already. Eddycurrent hinted at this in a previous post I think.
    Neil...

    Build log...here

  7. #27
    For some reason I don't like the look of the box section as brackets for X ball nuts.
    You seem to be loosing a fair amount of travel in Y direction by having short rails and ball screw.
    Think about how you will access grease nipple on Z ball nut once it's all assembled.
    Will you put adjustable feet on the frame legs for uneven floors ?
    Can't see how you will adjust belt tension for the stepper motors shown.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  8. #28
    Also think about how you will bolt it all together, you'll struggle to get the bottom Z axis bearings on as the bolt holes will be covered at the back so you'll have to take it all apart if you need to gt at them. If you extend the top Z axis palte back you can machine into it the adjusting slots you need and also it tucks the stepper down out the way and lowers the height of the Z axis.

    Also don't forget that steel box section comes with rounded corners not nice square ones as you've drawn so you'll possibly need larger section (60 x 60) to be able to bolt the bearings to? I'd also extend the small plate you've got on the back of the Y axis for the floating bearing (small) mounting to provide a bit more stiffness for the Y axis, that way you'll not need any diagonal bracing.

    If you're not sure what I mean attach the sketchup file (if that's what you're using?) and I'll show you what I mean.
    Neil...

    Build log...here

  9. #29
    Hey guys Thanks very much for the replies, Unfortunately I was a silly boy and bought the supported rails kit before I knew anything about the subject from Aliexpress. the plan being I will use what I have for now but then look to either create another or upgrade to rails. I have made it wider also so that I can slide work pieces around a little and work with larger materials and then make a second continued cut although most of the things I do will be sheet material and smaller pieces but I wanted an all-rounder for things like my daughters dolls house I intend to make with the machine and other toys too for her and me !

    I didn't even think about the tensioning in all honesty that is a very good point I will make it on a movable faceplate. I couldn't think of a different way for the box for the ballnuts otherwise the other option being the ali route but though this might be better on the strength I might be able to make a silicone hose to the grease maybe although I'm not sure if it would just pop off.

    I will have a good think to see if I can make those better

    Thanks so much guys.

  10. #30
    Hey Neil

    Thanks very much for the offer of explaining it on the drawing I did try to attach the file but it doesn't seem to like it it seems like it only lets me do standard graphics formats. Is there another way to get it to you.

    Thanks very much.

    Rob

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