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  1. #31
    After getting no response from the laser cutting service on quotes I decided to have a route around in my stock and found some appropriate stock to mill some of the new parts myself.

    Yesterday I went ahead and milled two new motor brackets with spacing to suit the new Y ballscrews. Material is 6082 Aluminium which machines rather nicely with a single flute carbide end mill, I just have to slow things down a lot on my Momus CNC and use small diameter cutters as the Z axis is prone to flex.

    I can still achieve pretty accurate results though, it just takes time. I can't wait to have a stronger machine that can make use of adaptive tool-paths.

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    I hand tapped threads with the aid of my tapping guide, I've had some bad luck in the past with using the battery drill for tapping and since it's so difficult to find materials at the moment I was happy to take my time to avoid any broken taps/ruined parts.

    Whilst I was at it I milled four new feet, which connect the Ball-screws to the profile. Stock is 10mm thick and is set up so I can align the side of the BK15 holder to the top of the profile. These are tapped with M6 thread in four locations for the BK15 to bolt to with 45mm socket head bolts. There are then two 5mm fixing points for fixing to the profile. I may hide some countersink bolts under the BK15's too, for now it's fine.

    I went ahead and ordered two ball-nut carriers from a custom CNC bureau service, so I can keep moving on this. They should be here in a week or so I think.
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    Last edited by Evengravy; 15-04-2020 at 01:24 PM.

  2. #32
    So, Friday I managed to get some new laser cut steel through the post from a crowd in the UK.

    These parts will replace the current steel brackets which connect gantry on both sides to the ball nut holders. I used this as an opportunity to try welding for the first time. Please don't hammer me on the welding, I know it's shocking but this was my fist go at it and I've learnt a few things. One my 100A mig isn't nearly powerful enough for material this thick and, two; buying cheap gasless flux cored wire is a big mistake. If anyone is interested the Super 6 flux cored mig wire is something to avoid for a beginner at least. It creates plumes of black smoke, spatters like crazy (yep polarity is correct) and doesn't pool up very-well. If were to run the MIG again, I'd probably look to get some lincoln gasless flux cored wire, it seems to be well reviewed. Seems a bit pointless for this project, in future I'll be sticking to trying to learn a bit of ARC welding as I'm mostly interesting in sticking thick pieces metal together.

    Essentially I've built two of these and each is just tacked at this point and I intend to grind this mess back and get up to speed with the arc and come back to it. It does seem to be fairly strong though. Importantly it is square and key surfaces are flat so it a definite improvement on the last version a local company made, which were neither flat nor square (but welded better for sure). I'll be able to move along with the other bits when they arrive.


    Custom ballscrew nut mounts are on the way, then we can mount and test these new ballscrews!

    One I can confirm that everything lines up the way it should, I can use the steel from the old ballscrew mounts to practice some arc welding before coming back to these. At the moment getting steel is tricky. I intentionally didn't weld on the inside so I can tackle that later, after some practice.

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    Last edited by Evengravy; 17-06-2020 at 02:25 PM.

  3. #33
    I'd be very happy with that as a first welding attempt - nice one! But yeah MIG isn't going to be best for that material size - I'd be surprised if it has enough penetration.

    What's the phrase? Grinder and paint make me the welder I ain't.

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  5. #34
    Thanks Andy! it seems to be strong enough but I'd guess it's penetrated around 1-2mm into the base metal, or so (looking at the front corners). I can pass over the inside with the ARC once I get the hang of it too so I'm not too worried at the minute, I was more nervous to stuff up the alignment to be honest but it's bang on where it needs to be.

    I've been playing around with the ARC a moment ago on some scrap. I like it much more than MIG as a process so far, at least I can get a good pool going with it. Enjoying that a lot.

    I'm hoping to weld up a steel frame of some sort so it's worth learning something new whilst I'm about the house a lot.
    Last edited by Evengravy; 26-04-2020 at 04:34 PM.

  6. #35
    This morning two custom ballscrew nut mounts arrived from the CNC service, they came out really well so I followed on to test fit these and the newly welded (ahem) brackets. Click image for larger version. 

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    With a little to and fro to swap parts out I'm glad to say it all fits as well as I can expect, and boy does the thing feel much more solid now.



    I had to massage the brackets a little on the corner to give some wiggle room by adding chamfer the corner of the L to give a millimeter or two clearance.

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    I'm now just awaiting the new anti-backlash couplers to mate the motors to the new screws and this part should be done. It's been a bit of extra work, but so far I can feel the improvement and I'm glad that I took it on.

    If everything goes smoothly then I'll be removing these steel brackets and adding some more internal welds just to beef them up a little before painting them black and refitting. I'll need to start designing the table soon, I may be back to get some advise from you all when I get around to that part.

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  7. #36
    Hi John, It's looks great. In relation to the resonance you are experiencing in the Y axis are you running the machine with the Y axis unmounted to a surface or base? Do you only experience this when running the machine with the spindle on or off? Your selection of steps per revolution will also come into play with resonance as I myself experienced something similar. Endless tweaking and trying different combinations of steps per rev and mucking about with acceleration and deceleration settings got rid of it for me. Where are you based in Ireland? Liam.

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  9. #37
    Quote Originally Posted by AndyUK View Post
    I'd be very happy with that as a first welding attempt - nice one! But yeah MIG isn't going to be best for that material size - I'd be surprised if it has enough penetration.

    What's the phrase? Grinder and paint make me the welder I ain't.
    Mig is more than capable of welding that material, but 100A isn't. It would need 250-300A and thick wire. The trick with Mig is setting the wire feed correctly.

    Also when your butting 2 pieces like you have if you grind a chamfer on each edge where you want the welds it will give you a stronger weld as you have larger weld area, it also gives you a flatter weld with hardly any grinding required.

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  11. #38
    Quote Originally Posted by JAZZCNC View Post
    Mig is more than capable of welding that material, but 100A isn't. It would need 250-300A and thick wire. The trick with Mig is setting the wire feed correctly.

    Also when your butting 2 pieces like you have if you grind a chamfer on each edge where you want the welds it will give you a stronger weld as you have larger weld area, it also gives you a flatter weld with hardly any grinding required.
    Hey, yes sorry I was referring to my MIG in particular, I'm sure with more current it would work absolutely fine. Ten four on the chamfering, I'll keep that in mind for future.

  12. #39
    Quote Originally Posted by Mister Mills View Post
    Hi John, It's looks great. In relation to the resonance you are experiencing in the Y axis are you running the machine with the Y axis unmounted to a surface or base? Do you only experience this when running the machine with the spindle on or off? Your selection of steps per revolution will also come into play with resonance as I myself experienced something similar. Endless tweaking and trying different combinations of steps per rev and mucking about with acceleration and deceleration settings got rid of it for me. Where are you based in Ireland? Liam.
    Hey, thanks. Currently no base, I'm still considering the best approach for building the base at the moment. Some are quite unconventional lets say but I want to run high flow flood coolant for milling aluminium so I'm going to think about liquid capture etc. I'm going to try and CAD design some ideas over the weekend. I'm a bit limited with the current lockdown in sourcing what I would need anyway so no stress just yet. The vibration was really just coming from the screws themselves without the spindle running, which weren't great quality and not straight either. So, partly crappy ball nuts with lots of friction and play, partly non straight ballscrews plus a coupled hollow cavity = resonance. I'm not too concerned with the resonance part, that's in my field of expertise (I'm an acoustics/audio specialist) more concerned with the smoother motion that the new screws will provide plus hopefully less play (I'll need to measure that again today). I intend to fill the Y rails with either sand, pea gravel or epoxy granite to get rid of that resonance. I'll probably go cheaper options first and see where it is. I can measure the natural resonant frequency pretty easily and try to tune around it too. I'll keep those points in mind for sure though on tweaking, thanks for that.

    I'm based in Donegal buddy, you?
    Last edited by Evengravy; 02-05-2020 at 11:38 AM.

  13. #40
    I'm down in Co Meath for my sins.... Yes the Lock Down is a bummer but I believe we will be let out gradually from the 18th... Plenty of time to do design work! I forgot to ask what the cutting area of your setup is? It's a decent build for sure. I would 100% recommend flood coolant doing any serious metal machining or mist for lighter work otherwise you will get a pain in your ass replacing cutters! I settled on rack and Pinion after trying belt and lead screw. Both turned out to be disasters.No way I could afford 2.8 Meter Ball screws!! My Rig has been sitting idle for 2 years and only recently am I getting the Itch to start playing again.. The only bonus of the lock down!. Feel free to give me a shout it your stuck with anything. I have made shit load of mistakes building my setup but you live and learn and it may help you from falling into some of those pit falls!!!

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