Messages

1

General Mach Discussion / Re: My cuts are the wrong size...

« on: September 26, 2013, 11:03:52 AM »

Hey all, Again, I havent forgotten, just school holidays, rush jobs etc...

Im pretty certain that Im not losing steps anywhere, but have noticed considerable flex in the body of the machine. I had originally written this off in my head as unrelated but since realised (after a dumb moment, one of those get caught up thinking the problem is elsewhere) it could be a serious contributor to the issue. Though I think I might be experiencing a couple of small things adding up to create a bigger overall problem.

So again, once things calm down, I should be able to get back into it and finish the diagnosis...

2

General Mach Discussion / Re: My cuts are the wrong size...

« on: September 18, 2013, 07:14:09 AM »

I havent forgotten... Just flat chat at the moment!

I've done some tests, but I'll finish first before I post em...

Feed rate definitely changes things, also climb vs conventional direction... I've not check whether thats tool deflection or flex in the machine yet (moneys on flex to be honest)
Also, gauge dialled 1mm and it comes to 0.99mm

Anyways, I'll check more soon...

Thanks, Bill

3

General Mach Discussion / Re: My cuts are the wrong size...

« on: September 12, 2013, 08:38:08 PM »

Guys, thanks so much for your suggestions, I have a lot of testing to do!

I havent got back down to the workshop yet, but I check all these things and see how I go

I dont have a dial gauge myself, I'll harrass my old man and see if he has something suitable (it is his machine!)

Will let you all know my findings!

Thanks Again!

4

General Mach Discussion / Re: My cuts are the wrong size...

« on: September 12, 2013, 10:33:29 AM »

Fair enough, Will do!
and report back!

5

General Mach Discussion / Re: My cuts are the wrong size...

« on: September 12, 2013, 09:53:07 AM »

Yeah, that was my first suspicion also (Im a bit rough on bits )
But yeah, I verified that the bit size is accurate.
Also, I have the same issue using different size bits.

Generally it hadnt been a problem as, say all the bits for a project were cut on the router so, the 'scale error' matched and parts generally fit. As my material thickness varied a little, I'd hit issues where something wouldnt fit into a slot, so I thought that was why...

As you can imagine the problem becomes more apparent the bigger the piece I'm cutting (You see, Jupiter for my sons school project just didnt measure up quite right!   )

I need to start being a bit more professional now, so I need to find the cause...

Are there any strange offsets that can be set in Mach3 maybe?

I didnt actually setup this config, but maybe it's time I get around to making my own...



yeah the problem is the same on high speed and slowspeed cuts etc
Having said that, the error margin may be enough that the problem appears the same.
Tomorrow morning I'll cut a nice light and slow cut and a deeper high speed cut and compare them just to be sure!

6

General Mach Discussion / Re: My cuts are the wrong size...

« on: September 12, 2013, 09:16:24 AM »

I should point out also, that the problem is always the same, I mean, I can cut this 50mm square, then cut a whole bunch of other things and cut the square again and its exactly the same, so I dont believe its a backlash issue or a physical fault as such...

7

General Mach Discussion / My cuts are the wrong size...

« on: September 12, 2013, 09:14:41 AM »

Hey all,

I reckon I'm missing something stupid, but we'll see...

I use a 3 axis router and do my design and toolpaths in Vcarve.

My problem is everything seems to be around 1% out. Say I cut a 50mm Square using an outer toolpath, the resulting cut is about 50.45mm.
So Im thinking, ok the step count is not quite right for each mm

But, If I cut a 50mm inner profile using the same tool etc, it comes out to 49.55mm, so its not the step count (sorry cant remember the proper term in Motor tuning section) Mach3 is at the workshop and Im at home now...

Now, I've examine the resulting G Code for both these cuts and it appears to be perfect... So Im guessing its something in Mach3...

I've had this problem for quite some time, initially I thought it was worn out tools as I was only cutting small pieces and my material was never the same thickness, so I was fudging it a bit...
But now I'm doing a lot more work that needs to be as accurate as possible, not to mention efficient in my workflow ie no fudging!

Any ideas?

Like I said, I'll bet its something silly I've missed or taken for granted...


Thanks,
Bill