Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[JOGARA]

Sorry I meant 0.5-0.75mm.
I think it will be fine. Just need to rework a few things in my CAM

Thanks for the info

[Zeeflyboy]

Well you should certainly be able to do a lot better than that... why do you think you'll be stuck with that level of inaccuracy?

My admittedly limited testing has showed the probe (runout adjusted each time) to find centre of a bore to within less than 0.02mm.... a quick way to check this is to run a centre probe, take a note of the Machine co-ordinates rather than the work co-ordinates, clock the probe eg 90 degrees and run the centre probing again. note how much the machine co-orindates have changed by after it re-zeros, repeat that a few times at different clocks and the maximum variation in machine co-orindates gives you a good indication of how reliably it is finding centre.

Finding zero from probing two edges to find a corner is a slightly different kettle of fish as you would need to calibrate to take account of deflection before the probe triggers to get truly accurate results. Centre probing mostly gets rid of this issue as deflection occurs on both sides.

If machining using a jig/soft jaws, you can always ream a bore in the jig/jaw that will then serve as your zero point.

I would say with a bit of thought you should certainly be able to get two sided machining to within a very tight tolerance (in terms of repeatability - absolute accuracy is another question as you could for example be eg 0.1mm out on all dimensions but as they will all be the same then relative to each other it doesn't matter).

[JOGARA]

So after yesterday's work I think I worked out how I am ending up with this problem.

Pressing the STOP button on the remote results in whatever axis is moving to end up being 0.01-0.2mm off where it thinks it is.


Using the pause button is not having the same result from the looks of it.


What I need is for it to not go all the way back home after each OP because that is also resulting in it being out by a few 0.01s over time...

[edit] Will just edit out "G28 Y0 X0"...

[JOGARA]

So I am having much better luck today.

The probe is 0.1-0.2mm out on both X and Y but I think I am starting to see a pattern so should be able to just offset it next round.
Did end up with 0.2mm out on the Y with these cases but they are not being sold.




I keep getting this bump on the Y face. It is only a hair deep but you can visually see it and feel it.
It is where the operation starts and ends so I am guessing it is something to do with that, not having enough overlap to smooth it out if the bit is coming off the part too quickly?







My soft jaws work really well for holding the cases. Though these were milled back in the day and are not level any more. Probably because I removed them and put them back.
Don't think my vice is all that accurate as well, it not being a proper machinist vice does not help.
I wanted to get one but even on eBay they were £500 for the width I need.
As you can see in the second photo, they result in the chamfer being messed up on one of the edges.






Was able to do a nice chamfer on the button and other front face holes for electronic components.




Oh and instead of milling out 2-3mm of my mounting holes which I then had to go drill deeper anyway.
Used the chamfer bit to spot the holes so I can just do them on the drill press.
I was already doing them anyway as my 1mm endmill is only 5mm long and I need a few more mm depth.
Other holes like the big one in the middle needed to go all the way down which I can't do with a 3mm endmill that is 5mm long. Do have the 15mm long one that would work but rather just drill it with a 4.5mm that use machine time and an expensive bit...
Obviously the chamfer bit is not made for this, will be swapping it out for a spot drill bit once it arrives.
I have looked at drilling with the mill. I tried it but got horrid results. Though it was probably down to bad setup. Not sure if this machine is really capable of drilling though. Thoughts? https://www.shop-apt.co.uk/carbide-d...d-series-.html







[edit] Just taken out the parts from the vibratory tumbler and they are looking great.
Really love that thing. They go in for 4 hours and come out great.
So smooth even with some sharp edges. Shame it is such a pain to clean out, not done it yet but that drain port I need to fix...