Gantry design and FEA analysis

[Kitwn]

Yes I'm quite familiar with the bird poo welding technique : ). When you were welding, did you let the weld cool before removing the clamps and turn the piece around to clamp the other side or did you weld one side un-clamped, turn it over clamp it down and then weld the other side ? It you clamped down the first side then welded and turned over to weld the second side the clamps wouldn't have much effect on the first side at least ?- I'd be really interested to hear your workflow as I've alredy welded my Y axis and I am trying to improve my amount of warp in the rest of the build ( I'm using gaseless MIG, a very very basic machine), I've seen a bunch of you tube videos but haven't dialled in my sequencing yet.

You are overestimating my skill and ability! I used a cheap stick welder I bought online which is the only welder I have ever actually used. The pieces were clamped together with C-clamps and vice-grips and if I remember correctly I used a couple of pieces of wood as braces to keep the pieces as flat as possible. I don't have a welding table so worked on the gravel path outside my shed. I clamped everything as tightly as I could before I began and didn't undo any of the clamps until it was finished. Having spent the last couple of days properly aligning this machine for the first time I can say how pleasantly surprised I am with the result of my first attempt at welding. It's needed some shims to get everything level and parallel but has turned out very well I think. The important thing is to think about how you will make your design adjustable, where you will need to have joints that can take shims for alignment and how you will access those joints when the machine is complete without taking half of it to bits again.

[eci22]

You are overestimating my skill and ability! I used a cheap stick welder I bought online which is the only welder I have ever actually used. The pieces were clamped together with C-clamps and vice-grips and if I remember correctly I used a couple of pieces of wood as braces to keep the pieces as flat as possible. I don't have a welding table so worked on the gravel path outside my shed. I clamped everything as tightly as I could before I began and didn't undo any of the clamps until it was finished. Having spent the last couple of days properly aligning this machine for the first time I can say how pleasantly surprised I am with the result of my first attempt at welding. It's needed some shims to get everything level and parallel but has turned out very well I think. The important thing is to think about how you will make your design adjustable, where you will need to have joints that can take shims for alignment and how you will access those joints when the machine is complete without taking half of it to bits again.

Thanks for the advice, yes I think the joints and adjustability becomes really important- so many choices!

Not really, I'm pretty sure it would be best to have the Hiwin rails fix directly onto the plate (which will add some rigidity already, especially with the extra stiffness of steel, so would be worth adding into you simulation) I was meaning maybe either side of the ballscrew (assuming there's enough clearance) or even on the front either side of the spindle mount if there's space. Just trying to help you add some cheap rigidity :-)

Like this ?



That does seem like a great idea to add rigidity

I think I've read a few times that it's better to have the guide blocks fixed and the linear rails moving down on the Z axis- I've also seen this quite a few times on builds, apologies if this is not what you mean by saying ('best to have the Hiwin rails fix directly onto the plate')

[Kitwn]

Thanks for the advice, yes I think the joints and adjustability becomes really important- so many choices!

You then have to choose what measurements you need to make and instruments to buy in order to set those adjustments correctly. There are a lot of worms in the can but you learn a lot too.