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Messages - robertspark

231
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 07:44:02 PM »
Hood, have a look at the current eBay listing, the manual has been updated (I told Denis he should be shouting about it to try to sell it more)... Note you'll not have the latest firmware, but all that means is that you have a longer packet to send of unused information which will take about 1 second minimum at tool change.... My suggestions just bring this down to the useful code.
This link may or may not work...
http://m.ebay.co.uk/itm/MiniTHC-torch-height-controller-THC-/322003269901?nav=SEARCH

No not yet hoping for a run this weekend.

232
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 04:04:40 PM »
I like lua... Bit more forgiving than C or CPP

You looked at m4 or waiting for plasma or something else to make it of interest?

Sorry hood, hijacked thread

233
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 03:48:43 PM »
Ahh...

Been trying to understand the post processors for sheetcam.  Interesting stuff... Some of them make me wonder why did they do this or that but very interesting when you begin to look into it

...no expert by any stretch on the imagination.... Still learning (always)

234
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 03:10:19 PM »
... Presuming that is you turn the fan on with an m07 or m08....

Under the onpendown() function

235
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 03:04:40 PM »
Don't need a delay timer, just issue an m09 code to the sheetcam function finish().... Done

236
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 03:00:23 PM »
Hood, I've taken the plunge on one of those po-mo minithcs from Denis, and I had a good discussion with him about the caxis protocol.

Long and the short he has expanded the c-axis protocol which has reduced the amount of data required to send the TH voltage setpoint to the controller.

I have been playing around with a sheet cam post processor and sort of cut pasted, and created my own for the po-mo minithc which allows you to store the voltage setpoint with the tool, and send it to the controller under tool change.

I also now have a pmx 45, and noticed an error in the manual regarding feedrate in the conversion from in/min to mm/min but this has allowed me to create few feedrate equations that match the pmx manual settings.  All you do is tell it the material, thickness and ampage (30/45) and it will work out the feedrate directly in sheetcam... Must admit not finished the function on this one in the post processor.... And it's only for the pmx45.

Rob

237
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 02:59:16 PM »
Don't forget freezing water table in the winter.... Christmas break... Unheated container.

Yes has to be submerged as it reduces the oxidisation.

Can you not try the downdraft... Then adapt later?

If you are doing loads of cutting day in day out, or lost of SS or thin metal then yup, otherwise try the downdraft... Place fan in insulated box outside...with long hose?

Rob

238
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 02:41:01 PM »
You get a better edge with a water table plus stainless... And that improves with nitrogen (no black edges apparently)

Just what I've read... Sure someone will add some experience

239
General Mach Discussion / Re: Physical buttons for plasma
« on: April 28, 2016, 02:38:53 PM »
Yeah it was Dave to an eBay link

240
General Mach Discussion / Re: Need some advice!
« on: April 23, 2016, 02:23:38 AM »
You are trying to cut 1/2 thick, with a 1/8" bit, at 30in/sec (probably 30"/min!!!) With a spindle running at 2700 rpm

I am not surprised....

Normally the recommended cutting depth per pass is 1/2 the bit diameter maximum!

Normally this is too deep for some machines because of machine ridgidity.

Key to successful cutting.... Stick to recommend chipload, and adjust depth of cut relative to machine rigidity.

Have a look at this PDF
https://www.google.co.uk/url?sa=t&source=web&rct=j&url=https://www.vortextool.com/images/chipLoadChart.pdf&ved=0ahUKEwj3w4CUiaTMAhUrCMAKHdXnAg4QFggaMAA&usg=AFQjCNHnMpHe_xN6tiH2QKnNDzAZmU1-RQ&sig2=fb0NmmsnEPcCCZ6gHHWfiQ

Basically for a 1/8" cutter the chipload should be about 0.003/0.004"/tooth  (start with the 0.003"/tooth as birch is a hardwood)

If all your spindle will do is 2700rpm, then your feedrate is

0.003 x 2 (no of teeth on tool) x 2700 (rpm) = 16.2 in/min feedrate..... At a max depth of cut of 1/2 tool diameter (1/16")

If you want to do 1/2" in one pass.... You will need a 1" cutter and a very rigid machine.

I don't know how well it will work with plywood, but you could always try adding a finishing pass at full depth, the problem you have is that your tool is not very ridgid.... Being 1/8" dia and plywood not being the smoothest material as the grains are opposed..... But for this you look at the cutting face....
Say you have a 1/8" tool, and the recommended cut depth is 1/16", the cutting face area is 1/8" x 1/16" = 1/128" square, intended DOC = 1/2".... Therefore 1/128 / 1/2 (more correctly 2/128)  = maximum finishing cut of 1/64".... Which is not much.... Suggestion.... You need a larger diameter more rigid tool...

More flutes will increase your feedrate.... But not the depth of cut (DOC).... Only a bigger tool will do that (with a more ridgid machine that you probably don't have)

If you could use a 1/4" cutter at 2700 rpm, your finishing cut at full depth would be better.... (1/16")

And your feedrate would be 24.3"/min at a doc of 1/8".... But if your machine has ridgidity issues you may need to reduce this given you were using 1/8 cutters. And then proportionally adjust your finishing cut at full depth (1/2").

Also look at better cutters (onsrud for example) as you may get better chipload as you won't be guessing it ( they publish specific tables for tools.... And technical support is very good... Just ask the question and they will walk you through it... I know as I was failing to cut aluminium with one of their cutters (3/8", 1/8 dia cutter)

Rob