Computer for Mesa 7i76E

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27 Apr 2019 00:50 - 27 Apr 2019 00:57 #132037 by AgentWD40
Beginner here diving in the deep end.

I'm building a plasma table based on the v1engineering LowRider2 router table. It will run nema 17s and a hypertherm 45xp. I've already ordered (maybe prematurely) a 7i76E and a THCAD-300. I figured on the ethernet version because I thought it would be more flexible and I've read on this forum it is at least slightly less dependent on computer jitter. I have an old computer, intel Core i3 I think, that I had intended to use for this project. I booted the Live USB Stretch development version amd64-r13 and the max jitter was around 150k. It hovered around 20k but spiked when I was playing with the wifi...

Question #1. I realize Core i3 is intel, not AMD, but that's the correct version for 64 bit, right? I *kinda* remember reading I needed 64 bit, please correct me if I'm wrong.

Question #2. Does this Live USB itself use the preempt kernel?

Question #3. If I have to buy a new (to me) computer I'd prefer a mini pc. I've seen recommendations from a few years ago for j1900. Can anyone provide updated recommendations for proven hardware and what kind of jitter I should expect?

Question #4. What kind of jitter is acceptable to run a plasma table with nema 17s anyway?

Question #5. I did read in the wiki docs about interpreting the jitter results. I get the impression that higher step speeds require lower jitter and vise versa (hence question 4), am I off base here?

Question #6. Kinda switching topics here but can anyone recommend stepper drivers?
Last edit: 27 Apr 2019 00:57 by AgentWD40.

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27 Apr 2019 01:19 - 27 Apr 2019 04:24 #132040 by InMyDarkestHour
RTFM



Since that all you got from my trying to help ya. I thought I edit to suit your interpretation.
Last edit: 27 Apr 2019 04:24 by InMyDarkestHour. Reason: Adjusted reply to suit OPs interpretation of my trying to address each question in turn and suggessting he do a bit of search
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27 Apr 2019 02:19 - 27 Apr 2019 06:00 #132046 by AgentWD40
Replied by AgentWD40 on topic Computer for Mesa 7i76E

AnnoyingMutt wrote: Question #5: This is really only applicable to software generated step/direction (within certain limits)

Hmm. Perhaps I had a misunderstanding of my situation. So then I take it the 7i76e generates the steps/direction? Is linuxcnc just gcode sender at this point?

Searching the forum will yield some good topics relating to jitter & Mesa Cards.

Sorry, I promise I've been actively researching tons of different questions all day. The last thing I want is [edit] for anyone else to think I'm being lazy and not trying first to figure this stuff out on my own before bothering you all with questions.
Last edit: 27 Apr 2019 06:00 by AgentWD40.

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27 Apr 2019 04:21 - 27 Apr 2019 04:22 #132059 by InMyDarkestHour
Last edit: 27 Apr 2019 04:22 by InMyDarkestHour.

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27 Apr 2019 05:19 - 08 May 2019 20:14 #132063 by AgentWD40
Replied by AgentWD40 on topic Computer for Mesa 7i76E

AnnoyingMutt wrote: RTFM



Since that all you got from my trying to help ya. I thought I edit to suit your interpretation.


Sorry. You've misunderstood what I meant. That wasn't directed at you and I'm not unappreciative. I was just saying that I do try to look up my answers before bothering others with my questions.
Last edit: 08 May 2019 20:14 by AgentWD40.

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27 Apr 2019 05:21 #132064 by PCW
Replied by PCW on topic Computer for Mesa 7i76E

AgentWD40 wrote: Beginner here diving in the deep end.

I'm building a plasma table based on the v1engineering LowRider2 router table. It will run nema 17s and a hypertherm 45xp. I've already ordered (maybe prematurely) a 7i76E and a THCAD-300. I figured on the ethernet version because I thought it would be more flexible and I've read on this forum it is at least slightly less dependent on computer jitter. I have an old computer, intel Core i3 I think, that I had intended to use for this project. I booted the Live USB Stretch development version amd64-r13 and the max jitter was around 150k. It hovered around 20k but spiked when I was playing with the wifi...

Question #1. I realize Core i3 is intel, not AMD, but that's the correct version for 64 bit, right? I *kinda* remember reading I needed 64 bit, please correct me if I'm wrong.

You can use 32 or 64 bit but I would choose 64

Question #2. Does this Live USB itself use the preempt kernel?

Yes

Question #3. If I have to buy a new (to me) computer I'd prefer a mini pc. I've seen recommendations from a few years ago for j1900. Can anyone provide updated recommendations for proven hardware and what kind of jitter I should expect?

Most Mini PCs should be OK, just don t choose the lowest performance versions

Question #4. What kind of jitter is acceptable to run a plasma table with nema 17s anyway?

As long as the servo thread can run at 1 KHz you are OK even a few 100 usec jitter is OK in some cases
but NEMA17, Thats pretty darn small for a plasma table...

Question #5. I did read in the wiki docs about interpreting the jitter results. I get the impression that higher step speeds require lower jitter and vise versa (hence question 4), am I off base here?

If you have a 7I76E the step rate is independent of the host jitter, basically LinuxCNC tells the
7I76e how fast to step 1000 times a second but the hardware generates the actual steps
(up to 10MHz on a 7I76E )

Question #6. Kinda switching topics here but can anyone recommend stepper drivers?

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27 Apr 2019 05:41 - 27 Apr 2019 06:45 #132065 by AgentWD40
Replied by AgentWD40 on topic Computer for Mesa 7i76E

PCW wrote: but NEMA17, Thats pretty darn small for a plasma table...


I hear you. All I can say is it has been done before! We'll see how it goes. They've been proven to be adequate for this machine design as a router table. The gantry is very light weight compared to most that I've seen anyway.. not that I've seen a lot.

The design is the lowrider2 at v1engineering dot com if you're curious.
Last edit: 27 Apr 2019 06:45 by AgentWD40.

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27 Apr 2019 10:48 #132080 by tommylight
Replied by tommylight on topic Computer for Mesa 7i76E
Using Nema 17 can be done and has been done, had some 1.7A on a 2.5x1.5m plasma table, gantry was the 2.5m side of it and with two such motors directly driving the belts it could do 18m/minute, at 500mm2/2 acceleration.
Important is to have a light gantry but firm enough so it does not flex when moving. That flex will show on cuts, and it never looks good.

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