Page 4 of 6 FirstFirst 123456 LastLast
Results 46 to 60 of 84
  1. #46
    Join Date
    Feb 2008
    Location
    Australia
    Posts
    988

    Default

    Been busy but still managed to get some plates done. Just 2 small plates left to machine and then to start working on the table.
    Attached Images Attached Images

  2. # ADS
    Google Adsense Advertisement
    Join Date
    Always
    Location
    Advertising world
    Posts
    Many





     
  3. #47
    Join Date
    Feb 2004
    Location
    Oxley, Brisbane
    Age
    79
    Posts
    3,041

    Default

    That is a solid looking bit of machinery there Chris.
    Bob Willson
    The term 'grammar nazi' was invented to make people, who don't know their grammar, feel OK about being uneducated.

  4. #48
    Join Date
    Feb 2008
    Location
    Australia
    Posts
    988

    Default

    Quote Originally Posted by Bob Willson View Post
    That is a solid looking bit of machinery there Chris.
    yea it feels solid, tried lifting one side a short time ago and it wasn't going to budge, it has to be over the 200kg mark now I reckon and I've still yet to add some 100x10mm steel flat bar for a homemade T-slot table.

  5. #49
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    769

    Default

    Awesome looking work - and having noticed your hold-down method, there's a length of DIN rail in the shed that's getting chopped up soon

  6. #50
    Join Date
    Feb 2008
    Location
    Australia
    Posts
    988

    Default

    Veryyyyy slowly getting there.

    Some pics of the table, 100x10 MS & 65x10 MS, just needing to machine up another 47 spacers in 8mm MS.

    Used M8 nuts as spacers for 12.8mm spacing for T nuts, the nuts on my mill have a width of 12.3mm so I'll try buying more of those or machine some from scratch.
    Attached Images Attached Images
    • File Type: jpg 3.JPG (217.0 KB, 85 views)
    • File Type: jpg 4.JPG (223.2 KB, 70 views)
    • File Type: jpg 5.JPG (233.9 KB, 59 views)
    • File Type: jpg 6.JPG (140.8 KB, 58 views)

  7. #51
    Join Date
    May 2003
    Location
    Perth WA
    Posts
    3,784

    Default

    Lot of work in the table T slots. Keep up the good work.
    Cheers,
    Rod

  8. #52
    Join Date
    Aug 2010
    Location
    Glenbrook NSW Australia
    Posts
    705

    Default

    Looking good Chris
    Thanks for letting us have a close up look at your cnc....Must make a start on mine sooner or is that soonest....
    vapourforge.com

  9. #53
    Join Date
    Feb 2008
    Location
    Australia
    Posts
    988

    Default

    Thanks rod and russell, once the shims are done, it's off to the sandblasters for the PFC, paint it all up, and finally assemble it for the last time.

    It'll be good to see what you come up with russell, I learned a couple of new things when you dropped by so it's a win-win situation

  10. #54
    Join Date
    Feb 2008
    Location
    Australia
    Posts
    988

    Default

    Table assembled. Now I'm just hoping the PFC doesn't bow too much and need a mid support, it's supporting 95-100KG.
    Attached Images Attached Images

  11. #55
    Join Date
    Aug 2010
    Location
    Glenbrook NSW Australia
    Posts
    705

    Default

    Chris To stop your PFC bowing you could epoxy some carbon fibre tow on the bottom side Or just straight glass would also work. This would stiffen it up a lot with little inconvenience.
    Just my 3 cents worth (note the inflation)

    R
    vapourforge.com

  12. #56
    Join Date
    Feb 2008
    Location
    Australia
    Posts
    988

    Default

    I've never worked with fibreglass or kevlar before, I'd probably just make a mess

    Took some measurements with the dial indicator (weight was within a 15cm radius of the dial)

    Front row - middle (weakest point)
    12.5kg - 0.04mm drop
    27kg 0.1mm drop
    100kg 0.38mm drop

    3rd slat from side, 2nd row
    12.5kg 0.01mm drop
    27kg 0.04mm drop
    100kg 0.1mm drop

    I'm pretty happy with those figures, but if I decide to add a mid table support it wont be any harder to do at a later date.

  13. #57
    Join Date
    Aug 2008
    Location
    Perth
    Posts
    31

    Default

    Hi Chris,

    Your measurements are probably torsional deformation and local bending of the channel top flange. Your channel flexural bending deflection should be less because of the very short span. Shear center of channels doesn't line up with their web (or your load line). This introduces local flange bending and O/A section torsion. Both I beams and channels have low torsional stiffnes (compared to say hollow sections).

    Regards
    Zvon

  14. #58
    Join Date
    Feb 2008
    Location
    Australia
    Posts
    988

    Default

    Thanks, so you'd suggest replacing the PFC with RHS?

  15. #59
    Join Date
    Aug 2008
    Location
    Perth
    Posts
    31

    Default

    Quote Originally Posted by Ch4iS View Post
    Thanks, so you'd suggest replacing the PFC with RHS?
    Ups, (red face) it seems that my fingers are quicker than my brain as I typed the comment above without reviewieng the photos on previous pages of this thread. The side channels cannot twist much because they are restrained by the table support channels. Correct me if I'm wrong - your table flat bars are supported by four (4) channels (PFC's) that span between the bottom flanges of side supports (white PFC's). The table support (blue PFC's) are toes down.

    Your deflection measurements are logical because of the load shedding - the flat bars shed load sideways and engagge adjacent channels. The edge (front and rear) channels can shed load in one direction only and the central ones in both directions.

    In regard to the table stiffeneing you can:

    1. Epoxy carbon fibres to the channel toes as sugessted above, however it would increase the section strenght more than stiffness which you would be after.
    2. You can box the table channels by welding a flat plate/bar 6-8mm thick between the channel toes (creating a RHS section) however it would require a lot of welding. The stifness should be increased and deflections reduced by about 2 times.
    3. The most effective way of stiffeneing the table would be provision of a midspan support which may be supported by the blue framing SHS (I'm not sure if you have a rear SHS)


    If you give me a rough sketch with members sizes I can model the frame and give you theoretical improvements (deflections) before you embark on a major table rework.

    Sorry about my previous post, I was under impression that you were concerned about the side PFC's (white).

    And yes, I prefer hollow sections (RHS/SHS) to open section (PFC/I). The trosional stiffness of hollow sections is an order of magnitude higher than for open sections.

    Regards,
    Zvon

  16. #60
    Join Date
    Feb 2008
    Location
    Australia
    Posts
    988

    Default

    No worries , I've attached some pictures of the frame to give you a better idea.
    Attached Images Attached Images

Page 4 of 6 FirstFirst 123456 LastLast

Similar Threads

  1. Steel cut off table build
    By dazzler in forum METALWORK FORUM
    Replies: 4
    Last Post: 6th January 2011, 01:00 AM
  2. Shed build - wood vs steel
    By ubeaut in forum ELECTRICAL
    Replies: 0
    Last Post: 16th November 2008, 07:18 AM
  3. Help welding Ally
    By Smicko in forum WELDING
    Replies: 16
    Last Post: 10th May 2008, 10:26 AM
  4. When Ally aint Ally!
    By BobL in forum METALWORK FORUM
    Replies: 22
    Last Post: 21st January 2008, 11:36 PM

Tags for this Thread

Posting Permissions

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