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  1. #1
    Initially posted here:
    http://www.mycncuk.com/threads/11310...-advice-please

    Decided I'm at the point where a build log is in order. Still looking at wood only, but would like to toss 3D carving into the mix. Table is built from 2"x2" square tube steel, 1/8" thick. I will be adding steel strips for more thread engagement where needed.

    Ordered linear rails and ballscrews for Y-axis (X-axis?, still haven't figured that out) from Fred at BST. Trying the 20mm Chinese ones. Saving the 35mm NSK surplus ones I ordered before for a later project.

    I know I'll get bruised up a bit for this, but I am somewhat "designing as I go". Getting handier with F360 though, so I'll finalize a gantry design before going that far. Here's what I have for now:

    Click image for larger version. 

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    Ordering epoxy to provide coplanar place for mounting rails. Gantry thoughts are something similar to what Joe Harris is building. Looking at 1.5kW water-cooled spindle with ER16, 4 bearings, real HY VFD.

    Questions:
    1. More bracing needed? I am thinking of angled supports for top rails.
    2. Any experience with the Chinese rails from BST?
    3. What should I be thinking about now to avoid headaches later?

    Thank!
    Wallace

  2. #2
    Hi Wallace,

    I would brace the underframe a bit with either some vertical pieces mid span, or diagonal across each side.

    1.5kW spindles often come with ER11 collet (max 7 mm), although some are ER16 (max 10 mm). But my advice is go for 2.2 kW and ER20 (max 13 mm) as it will give you more options. The extra power will help with the torque at lower speeds. They are all 80mm diameter for the main body so shouldn't effect your design.

    If the gantry will ride on those side members is there enough clearance in Z movement to the bed? Check they are going to be high enough.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  3. #3
    If I did a couple vertical braces mid-span, you think I'd have to then add legs in the middle too?

    You are dead right on the collets. I have an ER32 shank for my Bridgeport and was thinking ER16 was ER32 (powers of 2...damn computer geek :). I'll look at 2.2kW spindles.

    Not sure I understand the Z clearance question... I'm planning on a beam gantry (if I have my terms correct), so wouldn't taller sides give me the clearance needed? Within reason of course.

    Thanks,
    Wallace

  4. #4
    Taller sides will get you there! And from what I understand that's perfectly alright for wood routing.
    If you plan on aluminium then raising the frame sides are a more rigid solution then taller side plates for the gantry.

    Glad to see that you are progressing :D

    Skickat från min SM-N910C via Tapatalk

  5. #5
    Also the braces that routercnc mentioned are most likely diagonal braces.
    If you brace diagonally in as many directions as possible it will reduce flex in the entire machine when you are routing full speed later.

    Skickat från min SM-N910C via Tapatalk

  6. #6
    Added these:
    Click image for larger version. 

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    Epoxy should be here this week...

  7. #7
    That's good in front to back direction.
    Side to side could use some diagonal lovin aswell ;)

    What epoxy have you ordered?

    Skickat från min SM-N910C via Tapatalk

  8. #8
    Yeah, you're probably right. Sigh, I never thought I'd get tired of welding!

    I may get some grief, but I ordered Totalboat 5:1 epoxy. Supposed to be equivalent of West at about half the price. Actually, it wasn't so much that it was cheaper - they had a nice kit on Amazon with resin, slow hardener, metered pumps for each, and mixing containers. Specs have viscosity with slow hardener at 700 Cps, which is actually lower than West's 1000 Cps. So should flow as well or better.

    Thanks,
    Wallace

  9. #9
    Quote Originally Posted by wallyblackburn View Post

    I may get some grief, but I ordered Totalboat 5:1 epoxy. Supposed to be equivalent of West at about half the price. Actually, it wasn't so much that it was cheaper - they had a nice kit on Amazon with resin, slow hardener, metered pumps for each, and mixing containers. Specs have viscosity with slow hardener at 700 Cps, which is actually lower than West's 1000 Cps. So should flow as well or better.

    Thanks,
    Wallace
    Being a skin-flint I'm very curious how successful different cheaper epoxies are at self-levelling, so please report back when done.

    Had a look on the web and wonder whether you've gone for just the Slow-Hardener or the Extra-Slow-Epoxy-Hardener which seems to me to be closer to the West system that the successful pours on this forum have used?

    5:1 Slow Hardener ~ http://www.totalboat.com/product/51-slow-hardener/
    • Excellent thin-film characteristics provide smooth flow-out and self-levelling ideal for coating and laminating
    • Pot life @ 75°F: 20 minutes
    • Set time @ 75°F (thin film): 10 hours
    • Cure time @ 75°F (thin film): 1-4 days

    Tropical Extra Slow Epoxy Hardener ~ http://www.totalboat.com/product/tropical-hardener/
    • Excellent thin-film characteristics provide smooth flow-out and self-levelling ideal for coating and laminating
    • Pot life @75°F: 46 minutes
    • Set time at @75°F: 20-24 hours
    • Cure time at @75°F: 4-7 days

  10. #10
    I used reactive resins slow kit. Don't remember the exact specs for it but it worked real good :)
    It was about half the price of West 105/209 and it shipped to Sweden without hassle!

    Skickat från min SM-N910C via Tapatalk

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