Page 2 of 4 FirstFirst 1234 LastLast
  1. Jazz! Lol will do matey I've been promising you some pics for donkeys now time i pulled me finger out.

  2. In wonder if you didn't have anyone to do your machining for you then i could perhaps work something out with you.

  3. #13
    If you are worried about any twisting forces you can weld some stiffeners ( viagra as they are called ) inside the "c" section of the beam as Jazz says. This will stiffen it up nicely.

  4. #14
    AdCNC

    Got it... Will make the change as soon as I get the program started up again.. :)

  5. #15
    AdCNC

    Hmmm, I'm not sure having you doing my machining will be a cheap thing. I live in Denmark, so it's a bit of shipping back and forth... :P

    Web Goblin
    Yeah, I have thought of adding som braces to the back of the UNP profil. There's enough room for it..

  6. Lol lets rule that one out then haha

  7. #17
    Dont you deliver Ad?

  8. I can do yeh but it would cost a fair bit for a bit that weight, all for it tho.

  9. #19
    Quote Originally Posted by m.marino View Post
    Also Jonathan I know you have FEA software so if you have the time run realistic loads through and see what you get.

    Ok, I've done a very quick simulation as I don't think it adds much to the discussion since I'm only comparing the stiffness of sections for which the equations are already well documented. Granted the rails add a bit of stiffness, but it's not that great in the whole scheme of things.

    Click image for larger version. 

Name:	GantryBoxFE_Displacement_1.jpg 
Views:	198 
Size:	376.8 KB 
ID:	7986Click image for larger version. 

Name:	GantryChannelFE_Displacement_2.jpg 
Views:	211 
Size:	370.2 KB 
ID:	7987

    That's run with a 20N force, so nothing serious, at 200mm from the bottom of the gantry. Deflection at this distance (i.e. the tool) is 8.3um for channel and 1.5um for box section.

    Before everyone starts pointing out flaws - this model is just a quick simulation to demonstrate the principle, not the exact machine, except for the UNP160 dimensions which I got here, so the exact numbers are not important. What's important is to note that just using the same size RHS made the deflection over 5 times less than with UNP160. This model assumes the ends are perfectly rigidly fixed, so in reality it will be worse.


    Quote Originally Posted by IN-WondeR View Post
    The rails are already mounted on top of a welded on piece of steel, which will be machined flat to true up the rails.
    A Datum edge, is that a straight edge I can mount one rail along, so it will be true to the surface of the machine?

    Partly that, but also to help mount the rails straight and parallel.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  10. #20
    Quote Originally Posted by Jonathan View Post
    What's important is to note that just using the same size RHS made the deflection over 5 times less than with UNP160. This model assumes the ends are perfectly rigidly fixed, so in reality it will be worse.
    Ok then now do it agian with 2 Viagra braces has Web goblin calls them equally spaced and see what happens.?

Page 2 of 4 FirstFirst 1234 LastLast

Similar Threads

  1. New member looking for advice on a good quality machine (brand)
    By steve78 in forum Marketplace Discussion
    Replies: 1
    Last Post: 16-08-2014, 09:25 PM
  2. Desktop size build to learn on - PCB routing / small MDF work.
    By dynamis_dk in forum Gantry/Router Machines & Building
    Replies: 10
    Last Post: 26-02-2014, 11:50 PM
  3. NEW MEMBER: Brand new newbie
    By Grit monkey in forum New Member Introductions
    Replies: 19
    Last Post: 09-10-2013, 10:09 PM
  4. Stepper shaft size and pulley bore size problem
    By psiron in forum Linear & Rotary Motion
    Replies: 13
    Last Post: 15-06-2010, 04:11 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •