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  1. #61
    Lee Roberts's Avatar
    Lives in Wigan, United Kingdom. Current Activity: Viewing Moderator Control Panel Has been a member for 9-10 years. Has a total post count of 2,545. Received thanks 161 times, giving thanks to others 652 times. Made a monetary donation to the upkeep of the community. Referred 10 members to the community.
    Quote Originally Posted by Tenson View Post
    Now it's not quite a perfect fit because the top of the nut is slightly ~0.5mm) taller than the top of the bracket housing. So one could either fit a thin sheet on top of the bracket, or trim the top off the nut if you can figure out how to do it.
    You could use shimming steel to do this, a bench grinder can also be used to take the nut down a little.

    Quote Originally Posted by Tenson View Post
    Thanks Lee! Four of the six screw holes can be used, so I thought that is enough. I also considered putting a bit of lock-tight around the nut before inserting it.
    Humm are you sure?, the top two holes look as though they would pass through the mounting holes for the SMA unit, the middle two dont look like they would have much material for a thread because of the bore in the unit?

    As Jonathan said you may need to jig the nut about to get it concentric to the screw, all sounds a little to "make do" for me when a little creativity is all that is needed. Our right honorable gentleman Jonathan could properly fix you up with some custom mounts for a reasonable price.

    Somthing to think about also is machine maintenance in the future, maybe unlikly but what if a ball gets jammed or stuck in the nut and you need to take it apart....smash it out with a hammer ?!?!? Obserred, how dare you



    .Me
    .Me

  2. #62
    Quote Originally Posted by Jonathan View Post
    I wouldn't put lock-tight round it. You'll need a bit of room for adjustment when you first fix everything together to ensure the nut can be set precisely concentric to the screw.
    Do the mounts usually have much room to move? This fits absolutely perfectly and tightly so no room to move at all, although it could rotate a little.


    I've made a few ballnut mounts for myself and these for people on the forum:

    *Pictures*

    I hope you're not intending to use those unsupported rails on this machine?
    Very nice mounts. If I use your super rotating ballnut systems on the Y and X then I only need a nut-bracket for the Z right?

    The unsupported rails are for the 25cm Z axis.

  3. #63
    Quote Originally Posted by Shinobiwan View Post
    Simon, it seems like we're in the twilight zone here. We've both bought a CNC, we build speakers and now we've both saddled ourselves with partners who moan about all the MDF dust we walk into the house or that the dinning room isn't an assembly area.
    Eunji doesn't mind too much, she just wants me to sell lots! She is very understanding about hi-fi stuff too since she works in music. Actually she is very helpful in blind testing stuff since she did 3 years of critical listening training.

    Just for fun, a quick photo of the table in the living room right now, lol.



    You can build in a cover and have it vertical. Its more work in the design stage but can make for a really neat machine when space is an issue(when isn't it?). If I'd DIY'd I'd have likely done something very similar to this:

    http://www.denfordata.com/pdfs/produ...cal-router.pdf

    Very tidy package that would easily allow for a 4x4ft bed. All the crap falling into a pan at the bottom rather than all over the workpiece or into you rails etc. is another plus. Really there's not many downsides aside from increased build complexity and more awkward clamping. You could add vacuum bed later to solve the latter.

    If your spending the sort of money I think you are then its worth considering.
    Ooooh that is nice! I don't think it will save alot of space for me though because the gantry height, plus z-axis motor and machine frame end up about 65cm, and the width is only about 85cm. I think I'd prefer easy clamping. That said, I could easily turn the machine on it's side if I want.


    Good stuff but the ER16 collet might be a bit limiting. Can I ask why you choose that over the ER20? I looked around long and hard at cutters and most of the extra long series cutter are 12mm shank. These cutters allow thick(ie. 100mm) baffles to be safely machined.
    All the router bits I have are 6mm shank, and I have a fair bit of money in that. I also thought it was possible to just buy an ER20 collet... nevermind!

    So are you doing custom built speakers professionally now?

    I still need to have a go with Acourate!
    Last edited by Tenson; 29-03-2012 at 11:33 AM.

  4. #64
    Tenson that looks like my front room, my wife reckons it won't be long till I've got it looking like delboys flat in only fools and horses. Minus the inflatable dolls of course ;-)

    I wonder if we should start a thread on "How diverse are the things that we make?" That could be an eye opener! Got a few good ideas of my own.

  5. #65
    Quote Originally Posted by Tenson View Post
    Just for fun, a quick photo of the table in the living room right now, lol.
    Looks familiar :)

    Ooooh that is nice! I don't think it will save alot of space for me though because the gantry height, plus z-axis motor and machine frame end up about 65cm, and the width is only about 85cm. I think I'd prefer easy clamping. That said, I could easily turn the machine on it's side if I want.
    The gantry is offset by you being able to go upto 4x4ft. Generally a 4x4 will stick out at least 1400mm from whatever wall its pushed up against. Vertical would be less than half that.

    All the router bits I have are 6mm shank, and I have a fair bit of money in that. I also thought it was possible to just buy an ER20 collet... nevermind!
    When you say router bits do you mean the regular 1/4" collet types with straight flutes? They'll work fine but you might want to consider getting yourself some end mills. These are generally better quality, plunge much better, remove material better and last longer.

    Use up what you've got and once they're starting to dull get yourself something like these:

    http://www.ebay.co.uk/itm/1405488812...ht_3253wt_1163

    They're really cheap for what they are and were recommended to me by folks like Jonathan and Jazz who've used them to cut aluminium. They'll eat MDF and ply for breakfast and last ages.

    So are you doing custom built speakers professionally now?
    Pretty much but nothing official. Its mostly word of mouth but I hope to bring a small lineup of speakers eventually. There's a lot of planning involved before that can happen not to mention prototypes, listening tests, crossover tuning, auditioning. I had hoped to have a floor standing speaker available before the end of this year but I've recently taken on a custom project for Arthur(Ackcheng on DIYA) over in Hong Kong and its scale is very ambitious. A total of 8x 10" drivers, 4x 8", 4x 5" and a pair of ribbons all housed in 2100mm x 320mm x 750mm cabinets. Its the audio equivalent of the Deathstar.

    And last year I designed(not built) a huge OB dipole line array with seperate ripole sub stacks for a guy in New York. 8x 21", 18x 8", 16x BG Neo10's and lots of Mundorf AMT's. I believe he's now taken the CAD files to various machine shops in the US and is in the process of having them manufactured. Materials are alu and acrylic and the project is about the cost of a new mid range Benz.
    Last edited by Shinobiwan; 29-03-2012 at 03:26 PM.

  6. #66
    Quote Originally Posted by Tenson View Post
    The unsupported rails are for the 25cm Z axis.
    CAN NOT STRESS ENOUGH. . . . . .DONT DO IT. . . . ABSOLUTLY DONT DO IT.

    You will regret using unsupported rail and even more so on the Z Axis.!!

  7. #67
    Quote Originally Posted by JAZZCNC View Post
    CAN NOT STRESS ENOUGH. . . . . .DONT DO IT. . . . ABSOLUTLY DONT DO IT.

    You will regret using unsupported rail and even more so on the Z Axis.!!
    Simon, I'd really listen to this advice. I know you think you know what your letting yourself into here but honestly, you have no idea. I mean that in the nicest way possible.

    I had to have my Z-axis rebuilt because it was using unsupported rails and was shit. About +/-1mm of flex at the bit and that means you'll get a crap finish even in MDF with anything like a decent DOC and feedrate. Your parts will be undersized, oversized and generally a mess. And you can forget it if your thinking of aluminium. Plus your using a heavy spindle with heavy 16mm alu plate. That's a bunch of weight right there before you've even got to the cutting forces.

    Do your self a massive favour, ditch it and go with supported round rail. It'll add nothing to build complexity and hardly anything to the price. Cannot stress enough how shit round rail is, it should be banned on anything calling itself a decent CNC router.

    Listen to the knowledgeable folks on here and save yourself from a world of pain, you'll get you a much better finish, more accurate parts and will let you move up to harder materials like alu, Corian and so on.

    I'm trying to stress this because I fell in to the same trap your about to and its costs me a lot of money to put it right. Do it right the first time.

  8. #68
    Quote Originally Posted by Lee Roberts View Post
    You could use shimming steel to do this, a bench grinder can also be used to take the nut down a little.
    I'd be very wary of grinding a ballnut since any dust from grinding in the ballnut is a recipy for disaster. You could try and cover it up but I don't think its worthe the risk.


    Quote Originally Posted by Jazz View Post
    CAN NOT STRESS ENOUGH. . . . . .DONT DO IT. . . . ABSOLUTLY DONT DO IT.
    +1

    When I said earlier that 16mm rail would be fine 'if done right' I was assuming supported rails. You'll be much better off getting some SBR20 (supported) rails.

    The 6mm single flute cutters are brilliant...get lots! Although they are much better than most at plunging you shouldn't need to plunge - use spiral toolpaths or ramping. Router cutters with a 1/2Q shank are much much stronger than the 1/4" ones, so well worth the extra.


    Quote Originally Posted by Tenson View Post
    Very nice mounts. If I use your super rotating ballnut systems on the Y and X then I only need a nut-bracket for the Z right?
    Yes... but how long is the Y-axis screw going to be? It's a bit sledgehammer to crack a nut using a rotating nut on the gantry, althought it would work well.

  9. #69
    Don't under estimate the job the ballnut mount does.!!

    Ballscrew mounts, alignment and nut holding are crucial to a good working machine, if any one is off the slightest amount the result is friction.
    This friction as to be overcome by the motors, the motors lose torque as the speed increase. Has the speed increase's friction heats things up which inturn creates more friction sapping more power end result stalling motors or missed steps at best.!!. . . . Worse case things lock and prematurely wear away often quickly in tight ballnut's case and die suddenly.

    Saving a fiver can cost hundred.!!.. . . Is it really worth it.????

  10. #70
    Quote Originally Posted by Shinobiwan View Post
    I had to have my Z-axis rebuilt because it was using unsupported rails and was shit. About +/-1mm of flex at the bit
    I find that quite surprising. I rather thought with the very short length and least weight of any axis, the Z would be okay running unsupported. If it really is that bad I'll get some supported rails. Building a Z-axis assembly to have opposing supported rails seem quite tricky though at first thought. Any tips / pictures?

    Anyone want to buy 2x 30cm unsupported rails? ;)

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