Messages

51

General Mach Discussion / Re: programming novice (and I mean NOVICE)

« on: November 27, 2016, 01:21:29 PM »

I'll have a look in a few hours, can you list your XML profile?


Are you using a standard screenset or do you need a custom one.

Can msg or email me direct via the links on the left

52

General Mach Discussion / Re: programming novice (and I mean NOVICE)

« on: November 27, 2016, 11:20:31 AM »

Have you sorted this?

53

General Mach Discussion / Re: Just when you think you are finally getting there....

« on: November 27, 2016, 10:41:29 AM »

Given acceleration is generally fixed as high as it can be, I would suggest lowering the feedrate in the corners using your post processor (sheetcam can do it, no idea about vectric).

Basically lowering your feedrate 1mm before and after the corner to 60% will probably sort it ....

Sorry out and about at present, no pc access

54

General Mach Discussion / Re: Just when you think you are finally getting there....

« on: November 27, 2016, 09:07:17 AM »

https://www.khanacademy.org/science/physics/centripetal-force-and-gravitation/centripetal-acceleration-tutoria/a/what-is-centripetal-acceleration

If you had a 5mm tool, with tool compensation, at those feed and accel rates, I'd still expect a 0.8mm error as one axis must slow down and the other speed up to maintain velocity

55

General Mach Discussion / Re: Question on Plasma THC control to users of this facility

« on: November 27, 2016, 08:32:20 AM »

Adrian,  how are you doing the THC  (long term interest of mine.... better thc.... some people chase divots... I seem to chase THCs....)

56

General Mach Discussion / Re: Question on Plasma THC control to users of this facility

« on: November 27, 2016, 08:29:50 AM »

Highly recommend adam at http://www.vigortronix.com/
http://www.vigortronix.com/Toroidal.aspx

Buy direct from a manufacturer... you'll see their products resold via a numner of outlets (farnell, maplin, etc etc).

Adam is very helpful (and works odd hours.... I asked him a question on night at about 11, and after 4 emails till about 1am, transformer was bought and arrived next day....)

57

General Mach Discussion / Re: Just when you think you are finally getting there....

« on: November 27, 2016, 08:21:35 AM »

linear distance travelled during accel or deceleration -  0.5 x V^2 / a = 0.5 x (1000/60)^2 / 350 = 0.4mm

centripetal acceleration radius = V^2 / acc = (1000 / 60)^2 / 350 = 0.79mm

hence at a feedrate of 1000mm/min and with an accel (+decel) of 250mm/s/s, you are likley to end up with a 0.8mm radius on inside and outside corners ..... without consideration of tool offset which may affect this  given a 2mm dia tool is nt going to end up with a 0.8mm insider radius in the corners .... you may be looking at 1mm + 0.8 etc

then again all of the above could be bull!   (just something I'm reading up on at the moment.... I've not been under the hood with mach3 to figure out the tradectory planner following error )

58

General Mach Discussion / Re: Just when you think you are finally getting there....

« on: November 27, 2016, 07:44:30 AM »

What acceleration are you using?

The problem with mach3 is the CV mode tradjectory following is not tunable.... Like it is in some if the newer cnc software

59

General Mach Discussion / Re: Question on Plasma THC control to users of this facility

« on: November 26, 2016, 05:39:57 PM »

Nice butterfly, you did that with a cut40?

60

General Mach Discussion / Re: Question on Plasma THC control to users of this facility

« on: November 26, 2016, 03:55:30 PM »

I will have a read through the information you have provided, yes I have the manual for mine rated voltage is 100 Volts in the user guide.

The input is 4.7KVA at rated output of 40 Amps, so really wants a 22Amp supply but duty cycle is 60% at that those figures.

I need to run the machine under 25 Amps if I can reasoning is it is on a 13 amp socket.

220 Volts x 13Amps = 2860 KVA * 0.85% efficiency I have 2431 KVA available, 100 Volts rated so around 24 amps cutting current.

I can push a bit higher but the garage supply which is really only rated at 20 Amps has to power PC, lights and a compressor.

Thanks for the rest of the information I will read through the posts you have listed, thanks for that.

UK is 230v

100v(OP) x 40A(OP) = 4kW (OP)
4kW / 0.85 (%eff) = 4.7kW [so that checks out]
4.7kW / 230v = 20.4A

You can probably get away with a 16A BS60309 plug and socket [I do with my powermax 45 (45A @ 132V, 0.99 power factor = 5,940kW), 6kVA at 25A generator recommended]
http://www.toolstation.com/shop/Electrical/d190/Industrial+Connectors/sd2430/Industrial+Plug+IP44/p36175
http://www.toolstation.com/shop/Electrical/d190/Industrial+Connectors/sd2430/Industrial+Socket+IP44/p20698
advantage is that they aren't fused .... so have a bit more give than a 13A plugtop.
looking at another 3A per 1hp for the compressor (approx),

duty cycle is the operating time per 10 min duty cycle (hence 60% duty cycle means 6 mins run time, 4 mins cooloff).

on a 20A mcb, you can probably get away with around 30A maybe a little more at that duty cycle depending upon breaker or fuse type..... also you'll find that your actual cut time probably won't be 6 mins anyway (as that would be ~ 5m of cutting at your feedrate.... continious on a small table..... not really possible in my opinion
http://wiki.diyfaq.org.uk/images/d/d4/Curve-MCBTypeB.png
http://wiki.diyfaq.org.uk/images/thumb/d/d6/Curve-MCBTypeC.png/640px-Curve-MCBTypeC.png

I was told by a hypertherm technical person that as a guide (starting point) if you've got the feedrates for 40A, and reduce the ampage to say 32A (20% reduction), then your feedrate should drop by a corresponding percentage (roughly).