The Craftmans Shop > New from Old
Titivating A CNC Plasma Table
RodW:
Looking good.
Personally, I think adding extra blocks is overkill. a pair of them is rated to handle 457 Newtons of force. Divide by 9.81 and you end up with them being able to handle a 46kg weight at the end of a 1 metre long lever! Your torch will weigh in at around 0.8 to 1.0 kg at a guess. Specs are here
http://docs-asia.electrocomponents.com/webdocs/0f44/0900766b80f448f1.pdf
Once I looked at the ability of my Hiwin HGR15 slides to handle such forces, I just went with one slide for the Z axis mount and the float switch.
awemawson:
Thanks Matthew and Rod.
Rod, I've no doubt that they'll take the loading, but the existing Z main slide and floating Z slide are both based on single HGR15 sliders, but there is noticeable wobble at the torch from the magnified microscopic play in the bearings due to the distance from the bearing to the torch. (About 145 mm of beam length)
So by sitting both sliding platforms on (hopefully eventually) four bearing sliders set a reasonable distance apart there is a good amount of triangulation so even a small amount of play will be constrained. It just seems a better engineering solution - due to the slightly heavier construction my beam length is increased to 157 mm (*) but the whole thing is far more rigid :scratch:
(* actually that measurement is from the Z axis mounting plane so the actual beam length is about 60 mm less)
awemawson:
I went to the Plasma Table this evening, not to cut a part, but to sort a PC connectivity issue (not showing on my local network). Now usually I'd go to it, mount a bit of plate, load up a file, cut it and hot tail it out of the room. But this evening as I wasn't rushing to cut a part I noticed just how much crud had built up on the slats, and on the grill under the slats.
Quite amazing - I'd have said I was using it lightly but it looks like it's been going flat out for yonks ! In fact 17th Jan 2017 was the first cut - so not much over a year :bugeye:
Looks like I'm going to have to dedicate a bit of time to cleaning up, and probably reversing the slats - a bit scary how these things creep up on you !
awemawson:
A bit of free time today, as a delivery expected for another project didn't happen, so I unleashed myself on cleaning up the plasma table.
Basically just remove all the slats, clean off as much of the dross from them as possible with a hand scraper, run over them with a 36 grit aloxide sanding disk in an angle grinder, then put them back having swept up the fallings below the slats and in the catch pot.
I was expecting to have to replace some of the slats, but in practice they will be fine for another year or so. I've put them back with the affected ends reversed to maximise life. I've also tried to concentrate the bad bits in the 'far corner' where they will be least used. I suppose that they could be inverted with the dodgy face downwards in future so long as there is sufficient bearing at the three points where they rest on the supports.
Whole job took a good four hours and I'm now desperate for a shower after all that dross sanding.
kayzed1:
I bet one of those local farmers of yours is doing the night shift...
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