John's Alu Profile build

[Evengravy]

Don't understand why you are making the Y ball screw plate and the brace plate separate.? This could be made as one piece and will be stiffer and easier to fit.!

Hey,

I designed it this way just to give me scope for adjustments in each degree of freedom. I couldn't think of a better way of doing it to be honest, open to suggestions though.

I could get both parts made up from mild/bright steel and once everything is lined up get the joints welded. I picked up my MIG today and dusted it off, maybe I can get good enough with some practice to get it done myself.



Also there's scope to brace between the front and side section with some triangulated pieces.



Honestly not too clear how I could make it in one piece, but I'm probably being blonde...it's been known to happen.

[JAZZCNC]

Hey,

I designed it this way just to give me scope for adjustments in each degree of freedom. I couldn't think of a better way of doing it to be honest, open to suggestions though.

Ah makes a bit more sense now. I was working on your old setup and seeing all those holes which matched the profile ends I thought was fastening into ends.

Carry on.!! . . Lol

Edit: The drop bracket still needs some bracing thou.!! or a redesign of the whole thing.!.

[Evengravy]

Edit: The drop bracket still needs some bracing thou.!! or a redesign of the whole thing.!.

Yea, I was planning some welded triangulation braces between the two parts once it's all aligned properly, the overhanging section that mates with the ballscrew is annoying me but I'll come up with something to strengthen it up. Front plate will be heavy (15mm) but I know that will be a weak spot for flex. I'll play around with the design a bit more in CAD.

[Evengravy]

Edit: The drop bracket still needs some bracing thou.!! or a redesign of the whole thing.!.

Hey, so I've decided to go back to my existing design of the gantry to Y ballscrew connection which was 10mm steel plate welded and braced with 10mm triangular plate sections. After testing this arrangement on the Chinese screws for play, measured at the tool with my dial indicators I'm quite happy with it strength wise so I have redesigned the same arrangement to fit the new ball-screws. The current layout has between 0.02mm and 0.03mm of play which is largely coming from the ballscrew nuts themselves, you can feel a good bit of play by hand in the ball nuts when these are off the machine which does tighten up significantly when both screws are in the machine (weirdly), but I definitely got unlucky with these Chinese ball-screws compared to what others seem to get. There's noticeable bends in them too so out they go. Bare in mind the current ballscrews are running with angular contact bearings in the BK12 holders, which I bought after the fact, so those bearings tighten up the play in the Y. Initially play was in the order of 0.1mm+ in my measurements before and fitting angular contact bearings. I can't feel any play at all by hand in the new ground ball-screws so I'm confident they'll be a big improvement.

One catch with the new design is that I'll need to machine a ball-screw nut mount for the new ball-screw, one each side. Would anyone here be able to machine this part for me (x2) out of Aluminium for payment? I'd rather spread work here than a bureau service if anyone is free/able/willing.

I don't think my Momus will be accurate enough to do it to this depth to be honest, there's just too much play in the Z (part is roughly 57mm x 65mm x 70mm from Ali (6061/6082 etc))

Failing that I'll have to consider milling it in thinner 25mm sections bolted together until I can machine it myself from a single piece when the machine is in situ, but I'd rather get it done right the first time if possible.

I still need to consider the bracing of the gantry to the Y bearing block plates, but I'm happy enough I can do that after the fact pretty simply and am considering an adjustable design there.

I'm leaning towards setting this up in the standard horizontal arrangement atm, reason being I'm thinking of running high flow flood coolant on it and it's easier to manage that way.

[Evengravy]

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.



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.

[Evengravy]

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.

[AndyUK]

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.

[Evengravy]

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.

[JAZZCNC]

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.

[Evengravy]

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.