Sturdy and Fast all Steel CNC , my first build

[Jonathan]

Conclusion: With gantry and bead mounted in real working conditions the overall vertical deflection of the machine will be unmeasurable or less than 0.01mm which is irrelevant especially with 0.8kw spindle. So first impressions are perfect.

Your test shows that the deflection due to the frame will be very small (<0.01mm), but remember the linear guides and Z-axis especially will all lower the stiffness, so overall your deflection will be greater. Still, your gantry design looks reasonably strong so I expect it will be fine.

[Boyan Silyavski]

Your test shows that the deflection due to the frame will be very small (<0.01mm), but remember the linear guides and Z-axis especially will all lower the stiffness, so overall your deflection will be greater. Still, your gantry design looks reasonably strong so I expect it will be fine.

Thanks. I am aware of that. For me this build is a preliminary build to my real machine. A kind of experiment. Something like how far i could go at every step.

As the machine we all know is a sum of its components.I constantly meditate on "the machine is strong as its weakest part". The Hiwin blocks are with A preload, the deflection calculator tells me the gantry sides deflection cutting aluminum will be lower than 0.01mm, so i guess the weakest part will be the Chinese spindle bearings and the bit. I will be extremely happy if i succeed in making a precise machine, just for the sake of it.

[Boyan Silyavski]

I need some help here with the Leadshine AM882 drivers and the SY60STH86-3008BF motors from Zappautomation.

-As far as i understand the auto finding of the parameters using the dip switch would be enough?

-However i wonder what step/micro-stepping should i use with the 1605/z/ and the 1610/x,y/ ballscrews? having in mind the way i build the machine.

-Also about the Switch 8 at the drive.
the manual says:
Pulse signal: In single pulse (pulse/direction) mode, this input represents pulse
signal, each rising or falling edge active (DIP switch configurable); 4-5V when
PUL-HIGH, 0-0.5V when PUL-LOW

So i asume rising is Pul High and falling edge is Pul Low. I wonder which one will work with my C23 board from CNC4PC

[Jonathan]

The microstepping setting is generally first limited by the output frequency of your parallel port. Using higher microstepping can help with reducing resonance problems, although those drivers have more advanced ways to deal with that so it's hard to say. Generally people don't use finer than 1/8th microstepping as going further can reduce performance, but if you can even use that will depend on the maximum frequency your parallel port will output and the feedrate you require.

For example, suppose you want a feedrate of 8m/min (sensible for cutting wood) with the 10mm pitch screw driven via a 1:1 ratio with a parallel port that can only output up to 25kHz (a lot will do more, but not all):
Screw angular speed: 8000/10=800rpm
Base frequency: 800/60*200=2667Hz
25000/2667Hz=9.4 ... so nearest is 1/8th microstepping with the above conditions.

[EddyCurrent]

http://www.mycncuk.com/forums/machin...-mach-3-a.html

From what I've read 1/8 is a good starting point

RE. switch 8 I guess if it won't work one way then try the other

[JAZZCNC]

Bloody heel all that typing and Jonathan had already said it all . . Lol

RE. switch 8 I guess if it won't work one way then try the other

Not that simple Eddy it will work in either mode but if pulse is on wrong side then it will drop a step on direction changes.!

[JAZZCNC]

However i wonder what step/micro-stepping should i use with the 1605/z/ and the 1610/x,y/ ballscrews? having in mind the way i build the machine.

Well depends a lot on your PC and how good the parallel port is and what speeds your looking to achieve. PP and PC speed to some degree will determine the Kernal speed in Mach3 and how many pulses you can put out which in turn will determine the speed you'll get from the machine. Higher micro steps require more pulses to achieve same speed has lower MS but they give smoother running motors and to a lesser extent some resolution.
Personally I don't go higher than 10x or 2000ms and this is my preferred choice if PC can handle it. Higher MS also helps with resonance but these drives are great with handling resonance so it won't be a problem and if it is you can change tune it out using the software.

So i asume rising is Pul High and falling edge is Pul Low. I wonder which one will work with my C23 board from CNC4PC

I would agree but check with Arturo and I'm think it may even be possible to change a jumper on the board has well to suit but either way your covered because the drives allow it.
If you can't find out then you'll have to make some witness marks run some G-code and then check if it's lost position. If the pulse is on the wrong side it will drop a step on every direction change so won't take long to find.

[Boyan Silyavski]

Thanks a lot guys!

Yes 300ipm / 8mpm/ is the speed i aim considering the tooling/price and the spindle speeds.

8 microsteping was what i had in mind. I have tested the PC upto 100Mhz as far as i remeber and it was Ok. With other BOB, but i assume will run with this also.

Anyways i will make to files for Mach3, one for 100ipm and one for 300ipm, as the guy is new to this, so at first untill he is aware what he is doing...


On my small commercial machine the z steps in mach3 was set to 10000? this is quite high micro stepping, thats why i wondered, on the other axis is 8 microstepping. reverse calculating it the microstepping in z is 256, i am not quite sure now for the 10000 but it was ridiculously high.

[JAZZCNC]

8 microsteping was what i had in mind. I have tested the PC upto 100Mhz as far as i remeber and it was Ok. With other BOB, but i assume will run with this also.

Don't run that high thou otherwise high chance of troubles. Only set the Kernal speed high has needed and no more. 25Khz is the best and every increase above increases chances of trouble. Wouldn't go above 60khz no matter what driver test says or PC thinks it can do.!!
If you need that high pulse rate then buy motion control card, in fact I'd buy one anyway if you want the best performance from machine.!

[Boyan Silyavski]

Hi guys,
thanks to all for the valuable inputs.

For now i have to wait until they cut with laser the pieces, so i can proceed further.

Meanwhile as a thanks to all for the help , here is the Sketchup file/its in winrar format for easier transfer/. So anyone who wants can use it as it is, use parts of it or just use the components or table drawings. Before ordering the laser cut parts i revised it piece by piece and against the ballscrews, housings, etc. So all small errors are fixed. It cost me a whole day to rework it precisely. The empty spaces are for epoxy, there are some clearances where necessary. The machine has work area of 400x1000x200 . Any questions are welcome if you have something that is not clear. The main point being here is that the machine is completely scaleable up to the limit of the ballscrews or with minor adjustments even up to 4x8 , this without changing the type or thickness of the profile. Other main point is that the drawing is final drawing, no need for correction before real assembly, however there are some steps to be followed, but easy to figure when playing and simulating the actual assembly. If by channce there is a small error i will fix it right away in the future.



So enjoy it and thanks again. Will update when i have more to show.