The Craftmans Shop > New from Old

Titivating A CNC Plasma Table

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Spurry:
Luvverly job Andrew.  :thumbup: So, just the hole in the wall to do. Are you going to get the boys who did the Hatton Garden job along to assist?  :bugeye:
Pete

awemawson:
It's only single skin 100 mm concrete blocks so I reckon they'd be over kill  :lol:

Current idea is to chain drill with my 50 mm diamond core drill, hopefully from both sides to avoid breakout. I do have 110 mm and 125 mm diamond tipped core drills, but the smaller diameter hopefully gets me nearer the circle that I want.

awemawson:
This morning I attacked the wall.

I'd thought long and hard the best way to space 2" diameter core drilled holes reasonably accurately to give a 12" 'wobbly edged' hole, and in the end I came up with the patented angular hole spacer. Simply a bit of wood with two holes spaced 5" apart, one being 2" from an edge. One hole was used as a pivot, on a screw in the centre of the hole, and the other was a guide for a masonry drill. Drill one hole, then rotate the spacer so that the edge of the gizmo lines up with the last hole, and drill another. Worked like a charm  :ddb:

I then drilled these hole out to the guide drill size for the diamond core drill, and drilled out the core - it went remarkably easily, with the expected conical break out on the far side.

Then it was just a case of fixing the inner wall plate and outer cowl, and connecting up the 12" heat resisting flexible air pipe to the extractor fan on the table.

Hopefully this afternoon I'll get a chance to use the table in earnest

PekkaNF:

--- Quote from: awemawson on January 10, 2017, 10:41:18 AM ---"Scope Creep" -  uncontrolled changes or continuous growth in a project's scope. This can occur when the scope of a project is not properly defined, documented, or controlled. It is generally considered harmful.


Well it obviously happened on this project - I've just found myself ordering six 6003-2RS bearings - the assembly that holds the  gear wheels that engage with the racks on the machine each have two of these bearings - and at least one set feels notchy. Easy enough to change, silly not to really, but ...........  :scratch:

--- End quote ---

Luckily you haven't got feature creep!


That happens to me at the end of design phase and then I need to weed extras out.

Pekka

awemawson:
Well oddities abound - all excited I loaded up a sheet of 3 mm mild steel (zintec coated) and set it to cut out a 'bearing baffle' that I'd previously designed and cut on the table before I started updating it. It started off ok, measuring Z=0 and setting torch height, but when the actual plasma should have been initiated, movement stopped and the Hypertherm 45 displayed an error light showing 'loose consumables'

In the guts of the machine torch is a micro-switch that closes when the consumables are tightened onto the torch - I buzzed out the cables to the plug and everything was fine - closed when tight - open circuit when loose. Nothing to do with the CNC controller, this must be an internal issue with the Hypertherm - maybe something I disturbed when I remade the plasma voltage cable :scratch: . So I pulled the torch and cutter off the table, opened up the Hypertherm, and buzzed the switch all the way through to the main board - no issues. Put it back together and back on the CNC table, and tried again - same issue  :bang:

There is a button on the screen allowing me to trigger the torch on and off manually. Out of curiosity I clicked it, and initially there was a very weak release of compressed air - I did this several times then the torch fired up, no errors and full air discharge. I've come to the conclusion that the air solenoid in the Hypertherm was perhaps sticky and has now cleared, but why that should make it report loose consumables is a mystery  :scratch:

After that everything worked as it should - very odd. So here is a video of it cutting, and a picture of the result. Not surprisingly the cut quality hasn't improved since I did the re-build, but that's due to worn consumables and non-optimal cutting conditions controlled by program. Also there is an issue with the cut not ceasing fast enough at the end of a feature - I need to tweak the post processor to stop the arc marginally before the end of the feature to eliminate the nick it's producing.

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