What should an open source plasma cnc controller have ? At what price?

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14 Oct 2020 23:19 #186139 by tommylight
To much talk going on about controllers and reading some posts here and elsewhere seems like 3K is the lower limit for such a thing, so i wonder how should such a controller look and what should be in it to grant that price ?
I am sure using Lam Technologies drives and some Mesa boards will get the price quite high, but still not there.
So far i gather having a choice between 3 or 4 drives of DS1044 or DS1076 type, Mesa 7i96 or 7i76E and THCAD10 or THCAD300 should be more that enough for 99% of plasma needs, add a nice power supply or three a case and some terminals, it should do just fine.
At the other end of the spectrum, using a 7i92 with some cheap TB6600 (that are not 6600 but some n109 ones) and a THCAD would bring that price down nicely and it does work nicely as i am using one such system daily.
The difference between the two is nearly 1000 Euro, and they will both work perfectly well.
I am trying to get the price to roughly 600 to 800 for the cheap one and 1500 to 2000 for the big one with all the bells and whistles, but it will be tough due to some crappy tax laws here ( some of those laws are very nice :) ).
Thoughts? Ideas? Empty bottles thrown at me ?
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15 Oct 2020 02:46 #186145 by thefabricator03
Something to consider, the type of connectors.

I am using Microphone connectors for my I/O and encoder inputs because they are cheap and easy to plug and unplug. I have also found them reliable. www.jaycar.com.au/2-pin-line-female-micr...e-connector/p/PS2014

My CandCNC controller used plastic push on connectors and I did have problems with them coming loose a couple of times.

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15 Oct 2020 05:22 - 15 Oct 2020 05:43 #186147 by BeagleBrainz
Yep they are a pretty solid type of connection. Just Jaycar & Altronics are expensive, compared to aliepxress or ebay.

Is this for a commercial product or just recommendations for a DIY self built controller ?
Last edit: 15 Oct 2020 05:43 by BeagleBrainz.

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15 Oct 2020 05:32 #186148 by thefabricator03
Yeah they are a bit more from the stores but at least I can walking into my local Jaycar and get them that day. If I was to build and sell things that used them I would buy them by the 1000's from China.

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15 Oct 2020 05:56 #186150 by rodw
Funny you say that Tommy. I ordered a couple of custom made 60 volt 12.5 Amp AC toroids the other day with the same idea. I would use 2 x DS1076a and 2 x DS1073a Lam drivers. You would have to use a 7i76e I think to get enough IO as the drives will consume 4 inputs (fault) and 4 outputs (boost).

With the Lams, it won't be cheap.

I thought it would be a two piece controller with a control box and a HMI with built in touch screen with a 7i73 and a small PC. I figured that Lam puts it in the high end category so would include an industrial grade (non-usb) wireless pendant. You'd probably need to include a safety relay which adds to the cost...
So I figured I might as well price it at the high end...

I just perfected my Lam boost component. Video to come. Looks like it will be perfect and does not need an encoder.

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15 Oct 2020 07:46 - 15 Oct 2020 07:53 #186159 by pinder
for plasma, I see closed loop steppers, BOB and THCAD(or some DIY A-D) as the best(for money) option.(under 500$)

Only problem i face is limited input pins.
Options for more inputs are
1) MODBUS using some rs-232 to rs-485 converter (not sure if this will work)

2) arduino2hal

3) second parallel port BOB.
Last edit: 15 Oct 2020 07:53 by pinder.

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15 Oct 2020 07:56 #186160 by rodw

pinder wrote: for plasma, I see closed loop steppers, BOB and THCAD(or some DIY A-D) as the best(for money) option.
Only problem i face is limited input pins.
Options are
MODBUS using some rs-232 to rs-485 converter (not sure if this will work)
arduino2hal
or second parallel port BOB.


There is always ethercat.
Tommy has done one with 2 parallel ports and a THCAD.

I'm not convinced the closed loop steppers are a winner over open loop and good drivers like Lam Technologies. I had motors screaming out missed steps today and once i got the boost function working so a higher current was used on acceleration and deceleration, the problem was fixed because the motors had more torque when needed and plenty of time to cool down when at constant velocity at a lower current. I need to cut a full nest to see if it is a winner!

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15 Oct 2020 08:03 - 15 Oct 2020 08:03 #186162 by pinder

rodw wrote: There is always ethercat.
Tommy has done one with 2 parallel ports and a THCAD.

I'm not convinced the closed loop steppers are a winner over open loop and good drivers like Lam Technologies. I had motors screaming out missed steps today and once i got the boost function working so a higher current was used on acceleration and deceleration, the problem was fixed because the motors had more torque when needed and plenty of time to cool down when at constant velocity at a lower current. I need to cut a full nest to see if it is a winner!


Ethercat has alway been scary to me.
I have a hold of good ethercat servo drives at a reasonable price (200$each). Maybe I will have the courage some day.

One feasible option that i have tried in past with smaller motors is to use some heatsinks on two sides. I used white adhesive thermal paste which holds the heatsink on motor.

Looking forward towards your Amp control.
Last edit: 15 Oct 2020 08:03 by pinder.

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15 Oct 2020 08:10 #186164 by rodw

pinder wrote:
Looking forward towards your Amp control.


There is a video of it from today on my spaceship plasma thread. I'm not convinced about ethercat either.

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15 Oct 2020 08:18 #186165 by pinder

rodw wrote:

pinder wrote:
Looking forward towards your Amp control.


There is a video of it from today on my spaceship plasma thread. I'm not convinced about ethercat either.


I insist you for heatsinks.

When l will start making professional machines, this will be a must.
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