Mach 3 Feed rate issue

Hi. My dad and I are working on a CNC build. He is trying to get our motor feed rate to match the actual observable feed rate in Mach 3; but there is a mismatch.

We tell the motors (using two for x axis) to g1x1f10 (feed to X1" at a rate of 10" per minute)...so it should take 6seconds to make all the turns (slightly over 5 turns; as these motors are going to be used with 5mm pitch ballscrews).


The motors ARE making the correct number of turns but it's clearly not at that feed rate. Seems to take about twice as long, and even tho the FRO is set at 10.00, when it runs it lists at 4.61.

Any ideas where we have gone wrong here?

Pics of our setup attached here.

Any ideas what might be wrong?

-JP

 

Side note - we are thinking it may be the motion controller here. It was cheap {) and was supposed to be able to work with USB and Mach 3 - we thought we could try this as a means of avoiding using an old comp & old serial port connector. While we do have things moving, they just aren't moving correctly. Seems like we've tried everything in the software. Whatever the problem is - it doesnt appear to be a software setting (don't know for sure though). I have attached a short video of mach 3. You can see what i enter, when i hit start, and youll hear the motor kick on and stop. It's just off from the set feedrate (and the displayed feedrate is off from the actual feed rate and the set feed rate <:-D)

How do you match the displayed FRO with the programmed feed rate and the actual observable feed-rate (our rate of rotation)? Seems like this should have been easier but like everything else in life; we have discovered that it's never as easy as it seems <:-D

 

Hey Justin. Thanks for response.

These motors will be attached to left and right 5mm pitch ball screws which will drive our gantry in x. When I tell Mach 3 to move 1", that means they will need to turn a little over 5 rotations (25.4mm=1"; 25.4/5= approx 5mm per turn) and presently they do; they make just over 5 turns - they just do it slower than the speed I tell them to.

If I say 'motors - I want you to move 1 inch at 10 inches per minute' it should take 6 seconds to make the move from x0 to X1"(1min=60seconds, 60/10= 6seconds).

For some reason it isn't tho. And we can't figure out how to adjust everything so the listed FRO during the move reflects the amount of rotations in relation to time we count.

There is a video I attached on my builds page that shows this.

I'll continue building in meantime. I'm just wondering if there is some issue or if things are working and I'm just unaware of how to adjust something?

Thanks!

-JP

 

Justin,

Based on the info I give above; any idea what the issue could be? I realize my machine isn't totally built yet (but it is totally designed and I have all my parts); but how do I adjust the motors to spin the appropriate speed to match the given feedrate read out displayed in Mach 3? I don't even see a means of doing this. Seems like it's all just fixed relation (I realize I can adjust the actual % of FRO to make my motors go faster or slower on a cycle, but that's not what I mean - I am trying to figure out how to match the FRO with the speeds I'm seeing). If it's not the hardware in some area, then I must have something set wrong. I just don't know what that something is :/

Thanks!

 

Ok. But that's why I said 'any idea what the issue could be?'.

I realize I'm not yet pushing my gantry load, but I already have all the design/math worked out for absolutely everything. There isn't anything that is preventing me from learning how to calibrate what needs to be calibrated with respect to the motors and software.

If you can give me insight on what I may be doing wrong it will assure me that I don't need to order new hardware. I could just take your word for it, but at present I have no way to verify that you actually truly do have an idea what needs to be calibrated...so I'm still forced with the reality that I may have a hardware issue, which means I would want to get something else on order soon to try.

If you however tell me "no. I think it's this:" and proceed to give me some idea and explain how to calibrate my motors to work properly with Mach 3, then I will know for certain I'm fine on hardware.

Thanks

-JP

 

Well...I ended up abandoning my $70 China motion controller w/Mach 3 and got one suited to work with Mach 4, as well as a new copy of Mach 4.

Everything works fine now. No more feed rate issue.

I don't know what the issue was with the other board (or software), but evidently it was an issue with the board I had (or software).

May I suggest that next time if you don't know or are unsure on what you're talking about, just say 'I am not sure; but maybe ____?'. People will respect that a lot more than an attempt to sound very knowledgable without providing any useful feedback.

 

I never denied there may be a fix - sure; but of course I wouldn't know whether or not that's the case; since I've still been given absolutely no explaination on what the problem is....because you don't seem to actually know what the issue is : |

It's ok to not know something. Humility is a commendable value.

 

Hi Phillip; it was set at steps per inch.

I am pretty certain it was some compatibility issue. I ended up getting a copy of Mach 4 and a new motion controller (built for Mach 4) and everything works great now; it did during the test run anyhow - I need to finish building and hook it all up; but I was not seeing the same issue as I was seeing with Mach 3 and the other cheapee controller I bought.

Controls are one area I'm not so confident in; so I figured it'd be a bit of trail and error. Still would be nice to understand why it failed to work the way I had it at first!

Thanks!