Slaving axis (rotating nut, 2 steppers for Y-axis)

Now i understand!

I was looking for that kind of dell PC, but couple weeks ago i was in germany to visit my family and my brother gave me his older PC. He said he dont need it and i can test/use it for LinuxCNC if i want. Its has an ASUS M4A88TD-V EVO/USB3 motherboard, amd phenom ii x6 cpu, 64GB SSD, 8 GB or 16GB ram (dont know anymore, but i took 2
blocks out for my PC). Unfortunately that PC does not have an VGA but i used my NVIDIA GTX 770 from my PC.

I made an Jitter test for at least 1 and half hours, and stresses the CPU with GLXgears. I was really suprised and happy, because the jitter test showed an very good result:
Max Jitter(ns) 1.0 ms thread: about 6000
Max Jitter (25 us thread) : about 7500
It could be that it was opposite, dont know anymore.

I think thats an good result and i can use the PC without any doubts, or are thefd some other important factors which play an important role ?

denhen89 wrote:

Thanks for the explanation Andy!

@rodw: Then, maybe i should go for the Mesa cards...

Maybe i do understand something wrong, but it took you 12 month to get the 7i76e to run ? i hope i understand it wrong...

Nah, the 7i76e just came straight up, its been everything else that I've built from scratch in my spare time. It just took a good 6-8 months before I could actually use the card on some hardware! Plasma is not the easiest beast for a first build I have learnt!

Andy, I just updated my list of IO pins. I just added 10 more planned inputs and still have 1 spare pin! The outputs are faring a little better. I still have 11 left over. It is comforting to know I can add a few hundred more when required.

@rodw: Ahh now i understand! I am interested to see some pictures of your build, could you post some?

@andypugh: Yes, andy your calculation is correct, but you forgot to add VAT + delivery. I was already on checkout so i now that it costs 345€ include VAT (23%) and Delivery costs about 40-45€. I am not sure the exact amount, maybe it was 341€ or 342€, but i think that does not make an big difference.
I also wrote an mail straight Mesa, but the delivery costs was about 90€. So when adding VAT, then it makes more sense to order from eusurplus.com

@tommylight: I think also it should be an good Setup after the Jitter test and it would be even possible to use it for Solidworks or other modelling software, but thats not my plan. I think i will use it only for CNC and put nothing else on it.
When i made the jitter test, i opened about 6 x 720p youtube videos at same time, but i read that it makes not an big difference as long as only one is visible. But, i also used it for browsing etc. when the jitter test was running. At the beginning the Jitter was about 5000 and 6500, but then after GLXgears and couple videos + browsing it pushed the jitter to 6000 and 7500.
Now, i know that the Nvidia GTX 770 works really good with that setup, but that VGA still costs about 120€. On the other hand i dont want to risk and buy an other -much cheaper- VGA and have later problems with drivers etc. (i read the official Nvidia driver can make some problems).

There is another important factor that plays a very important role: the moment you see your machine making chips! That is the reward you get for many hours of work, learning, fixing, troubleshooting etc. Let me know when you get to that point, i will tell you to stop looking at it! You will not stop looking all amaised by it.
Have fun.

That motivates me, thanks ! I am awaiting this moment so much, but i dont want to hurry too much and be patient on the build.
For about 4 month i was reading every day about CNC. Have changed my Plans about 10 times. First Big machine, then small, then again big, and so on. But yesterday i bought 24meters CRS tubings (120x80x4 and 100x100x5), total weight was about 310kg, so i am ready to start very soon .
Right now, even i havent start to weld (on tuesday or wednesday - waiting for precize cut of all the tubings), i am already thinking how to build the gantry. I think i will build nothing special, but just to be able to start milling and later build and very rigid and heavy gantry.

Due to not much experience with Solidworks, i only modeled the main frame, without the 6 legs, stabilizations and all other stuff. It would just take too long to model the whole router...

I uploaded two pictures. Maybe you guys have some good ideas, even its a bit out of topic.

Thanks tommy, exactly that was what i meant with the "stabilizations". I bought extra 6 meters of 40x40x2, but i also have some 60x40x2 profiles left here at my place. I think it will be pretty rigid.

Right now i also think how to get the linear rail guides parallel on the long axis. There will be 1500mm distance between both rails, so it will be pretty expensive to buy that kind of precision square that is 1500mm long and rigid enough. Aligning them so they will be on same height i will do with epoxy, but getting the same distance between both rails will be not easy. I am not sure if the "self aligning" trick would be precise enough. What i mean is to put the gantry on the rails and move the gantry back and forward and do that for every screw. I am pretty sure you know what i mean.
Do you think thats an good idea?

Great! One problem less .

Im currently out with my dog next to my workshop so i thought to make an picture of the legs. They are not ready yet but i had almost 50cm left over of the 120x80 tubing so i thought its an good idea to build the legs out of it. Inside the tubing i will place/weld two 60x40 tubing just to make the leg stronger. Later i want to maybe add some leveling screw and close both sides with 3mm sheet metal for the look but i will of course left a cutting to get to the leveling screw.

*I have cut them with an angle grinder by hand, just made some marks, thats why it not perfect cutted.

Okay, it start become an build log. Let me know if i should stop to post it here.