Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
My stock in Fusion is the same size as my actual stock. My part is the same height as the stock so no offsets.
I am manually moving the bit down till it touches the surface. It has been more than accurate for what I am doing. Not 0.3mm out though..
I am pretty sure this is a thing in CAD though not the machine or my physical setup of it.
Quote:
Originally Posted by
m_c
I wouldn't make assumptions!
Are your previous setups still working as expected?
I can test tomorrow.
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
Are you measuring each piece of stock prior? There can be a lot of deviation on the extrusions, +inaccuracy from the bed and 0.3mm doesn't sound an unrealistic error at all. If you can use stock bottom as part zero and skim the top surface down slightly you will get far more repeatable results.
Also, if milling on a vice, have you trimmed/shimmed it? So that your jaws or soft jaws are square to your axis.
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
The stock is bang on 15mm.
The 0.3mm is across the length of my part.
I milled my soft jaws while in place so if anything it should be near enough perfect?
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
Stupidly knocked my soft jaws out of alignment today.
Losing the will to live atm. Looking for quotes for someone else to make them for me.
This machine is okay but I am just unable to get any accuracy when flipping the part, probably down to myself and this shit vice.
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
Good point about the soft jaws.
Stick at it. Flipping is an acquired art. I would really consider the approach I suggested a few pages back with a fixture plate to use for location and fixing after the flip. It's really quick and easy to make and use and well worth the hour or two it takes to make if you have more than a few parts to make.
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
No idea where to start in terms of making a fixture plate for these cases...
Vice is easy as I just chop out of the soft jaws the profile of what I am holding.
I have a feeling that this cheap vice is my major problem but also finding the work edge too.
I am now working from the center of my stock/part and using the external sides and halving them to find it, but I am finding it is still off a bit. I think that is more down to the inaccuracy of my probe setup if anything.
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
All you need for a fixture plate is a method for locating and holding the part and a feature to zero off.
I use dowel pins for locating, all you need is enough space on what will be your bottom surface after the flip for drilling two dowel holes. For fixing I don't think I've ever made anything that doesn't have a spare hole or two to put a bolt through to hold it down, on your cases you could just use stick a bolt through the big square holes with a large washer to grip the sides (one of the clamps that came with the OMIO would do). When you need to do an op on/around one of those bolt holes you just program a pause in your toolpath, move the bolt elsewhere on the part and carry on. For x/y zero I drill and ream a nice round hole to zero off, this is obviously at a known location because you have modeled it in CAD, the same goes for the dowel pins, and therefore from your X and Y zero feature you know where everything is to within the tolerance of your hole and dowel pin sizes, which I've never been off more than 0.2mm across the full 355mm length of the X. Z zero for me is always the top of the fixture plate, then when you're facing down the top of your part you know you are bringing it down to an accurate size.
If that makes sense?
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
Also another thing, have you checked your x and y axis are square? Because if they're not then you aren't cutting square shapes, you will be cutting trapezoids and that will show up badly with every flip. If you haven't aligned this yourself it will almost certainly be some way out, mine was massively out and took the best part of two days drilling, shimming, and hammering it all into shape.
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
[edit]
Just milled a part that worked before and it is correct.
Though I added 1mm body that I forgot to add to the setup so it milled 1mm lower in some parts than I wanted it to be.
It milled how the model is set up though so the depth I believe is correct. Will be able to fully check in a min.
I reinstate my comment on it being a Fusion360 thing not the machine or Mach3.
Re: Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet
If you think it's fusion, best thing to do is get on the autodesk forum and ask their techs. Their staff are generally quick and helpful at sorting things out, and there are some real fusion brains on there.