Just bought the NM-70, What should i do?

[braceary]

I just bought this machine, put all the plugs, parallel port, serial port in place, and install Mach and Bobcad.
What should i do next? is this require some special setting? on Mach and Bobcad?
how do i test the machine?

[ViperTX]

Open up Mach and check the settings for the ports, did the manual specify what the settings should be.

Check the motor config settings

If the settings are okay hit the tab key and you get a popup where you can jog each axis.

Now tune each jog, using a DTI, some 1-2-3 blocks (measure the block and see if you jog 1 inch you are actually moving one inch.

Paul

[ihavenofish]

get milling!



in theory, the xml file provided by novakon should have all the settings good to go, but it usually ends up needing tweaking.

other than whats mentioned above with regards to making the machine move the correct distance, heres a few notable things:

- check for backlash. the ball screws should have none, but mine for example had play in the ball screw bearing mounts. i just had to tighten them, and it was fine.

- run a long program with alot of straight lines and rapids in "air" with no tool. what you want to do is listen for any stalling. its a very distinct sound. if you can run through a 10 minute program several times with no stalling, you should be good. if it stalls even once randomly and then continues, this is usually because of the step pulse timing in motor tuning. this seems to be highly computer dependent, so whats in the default xml file might need tweaking. you can raise the number, or lower it. close motor tuning, run the program again. once you are confident there is no stalling anymore, you should be good to go. if youve tried every value and cannot stop the stalling, the core clock in mach may need changing, and i would call novakon for further instruction.

- check tram in the head. you do this with a dial or test indicator in the spindle over a large radius. you want to check it in the x and y directions, then compensate with shims at the bottom of the column if necessary. on this machine, .001" over an 5" circle is probably more than adequate but the lower the better. you can search for tutorials on how exactly to check and tram a machine.

- check the head for deflection. because of the way the ball screw is mounted in the back, and the short z saddle, there is a moment arm on the head when it changes direction. put a dial indicator in the spindle, and starting several inches up, slowly move the head down til the dial touches the table or a block. you need to be into the dial travel at least .05" for this test to be reliable. zero the dial, and then command the head to move up 0.03" in mach. you can do this by typing <g1 Z.03 f5> in the diagnostics page, or writing and running a program with that line. make note of how much the dial actually moves. also make note of HOW it moves during the command. you will see that the tool will actually move down first, then pause, then up.

on the new nm070 design, what you want is for that brief downward motion to be under .001", and the total "lag" on the direction change to be as small as possible. you can compensate for the overall lag(backlash) in mach, but the small opposite motion is something that can cause issues when drilling deep holes or pockets, and leave gouges in 3d contoured surfaces - like moulds.

if the deflection is too high, this may mean the gibs are too loose, and you need to tighten them. it can actually mean they are too tight as well, so it will take a bit of trial and error to get the best compromise.

dont be freaked out by all this though, what i "complain" about is only something detectable on high precision contouring and surfacing and it may be very negligable on your machine right off. i have one of the prototype machines as well, the new one is vastly improved in every way.

- AFTER youve done the stall test and optimised head deflection, you can tune the motors for top speed and acceleration. novakon uses very conservative settings. what you mostly want "faster" is acceleration. incrementally increase it while runing through the entire length of each axis travel. anything above 40 will be good. when you get to 40, stop, and then slowly increase the top speed of the axis. you should have no issues getting the X and Y to 100ipm. the Z will be slower, derpending on how tight the gibs were made in the previous step. anything above 50ipm would be quite fine i think. the x and y are actually capable of 250ipm stock, but its a complicated procedure in mach to get it there, so id not worry about it for now.

---

heres a few general suggestions for machining once youve gone through all the testing.

run shallow and fast. in aluminium or steel, it seems to do best with very shallow axial or radial depths, and high feeds. start with a good feed calculator and the tool makers speed recomendations as a guide, then tweak from there.

for example, in aluminium with a 1/4" bit i would go 1/8" to 1/4" deep, 1/64" to 1/32" width if possible. this seems to get the best finishes and fastest removal. steel is very similar, just slower.

hardened steel can even be done with some care.


hope that helps some