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

**JOGARA** · 17-10-2017

So I just used the probe and by hand found the center of one of the button holes in my case.
Was then able to chamfer the edges.
Not bad, not great. Was a hair out on the Y. X was perfect.

I just added 0.025mm to the Y and it is near perfect.
So Zeeflyboy your method works... :p

The real test would be machining around my part top and bottom now with out much, if any step in the surface finish once flipped and had the same operation done.

I guess the best way to do the flip is to leave 0.0something on the bottom of my stock and then flip, then remove that last 0.0something and chamfer...?

**Snapper** · 18-10-2017

Originally Posted by JOGARA

So I just used the probe and by hand found the center of one of the button holes in my case.
Was then able to chamfer the edges.
Not bad, not great. Was a hair out on the Y. X was perfect.

I just added 0.025mm to the Y and it is near perfect.
So Zeeflyboy your method works... :p

The real test would be machining around my part top and bottom now with out much, if any step in the surface finish once flipped and had the same operation done.

I guess the best way to do the flip is to leave 0.0something on the bottom of my stock and then flip, then remove that last 0.0something and chamfer...?

How deep is your case to cut in one pass? I don't think you will ever get this machine to flip a part and cut from both sides without leaving a step, but you should be able to make it small enough to sand and polish out.

Just to give an idea of the machines repeatability I zeroed in on the reamed hole mentioned above, moved my coordinate system over to the vice, milled out a part that was ~1hr machining time, came back to the reamed hole and it was 0.045mm out in Y and 0.02mm out in X.

You should be able to get the results you're after without probing everything. If this is something you're going to be making multiples of it would be well worth your time in making a proper jig.

**JOGARA** · 23-10-2017

So I finally got that grounding issue message. Guessing I just ground the spindle with the box of the controller?

**JOGARA** · 12-11-2017

Having some trouble with Fusion and I have no idea what is going wrong.

For some reason my heights are all over the place and is taking away too much stock on the Z.

Here is part of my case, in RED is what it is meant to be, and in BLUE is what I am getting (using my cheap caliper but it is pretty close to accurate).

I am using 3D adaptive clearing for the inside of the case, I set the bottom of the operation on the face of my part at the bottom. This is 2.5mm above the bottom of the stock (I have just switched to +2.5mm bottom stock instead of face selection). I then have another 3D adaptive to clear out the holes at the bottom of the case (I do this because I leave stock and then clean it up using a 3mm carbide).

Both operations are the same, just different heights and stock to leave.

(All my heights are .0mm or .5mm I don't have any heights that are .1mm other than telling it to go 0.2mm lower than the stock bottom for clearance reasons later in the setup)

Any ideas?

**Snapper** · 13-11-2017

There are so many things that could be causing this.

Are all those top surfaces cut by the same tool in the same set up? I can't see how you're cutting 1.7mm too deep from the side wall to the pocket surface, but then the pocket surface is only 1mm deeper than it should be compared to the bottom surface so I think this is a set up error. If you're sure you're setting your Z height accurately, its probably an error in the heights or stock to leave.

**JOGARA** · 15-11-2017

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.

**Snapper** · 15-11-2017

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.

**JOGARA** · 18-11-2017

No idea what is going on with my Z today. And in general the machine is acting up after working fine for a hour or two.

Just set my Z on my part, ran the program that worked before (doing the same op on the same part to test repeatability) and it just plunged 20mm down into it.
It now thinks the machine cords for Z are 20mm lower than they were just set using 2ref all home".

**JOGARA** · 21-11-2017

So I have spent all weekend and this week so far on this problem to no avail.
Had one guy on Fusion forum take a look but he could only simulate it so did not see the problem.

I just noticed on the operation I am running now it looked like it dropped a step.
Wondering if I am taking to much of a DOC or pushing too hard on the feed and it is pulling the bit?
Over time it would result it multiple height differences which I am sort of seeing but some heights are correct.

Once this operation is done ill touch off from the top of my stock and see where it thinks it is.

**JOGARA** · 21-11-2017

I have just touched off my part and it is saying it is +1.3mm.
Visually it looks like the bit is further down than it should be so I think it confirms that it is slipping.

I am using the correct collette size and it is tight when I insert the bit.
Not stupid tiht but it grabs onto the bit.
I am not over cranking the thread when putting it onto my spindle as I don't want to over do it. But it is still quite tight.

What is my best option here?