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

[JOGARA]

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]

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]

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?

[m_c]

What type of spindle/collet?

If it's ER, then it sounds like you're not tightening it enough. ER collets have to be tight or bits will pull out. There are torque settings for standard ER collet nuts, but typically it's as tight as you can get it with your hands and standard sized spanners, however that's assuming things are well anchored. On a freely spinning spindle, gauging tightness can be a bit tricky.

[Neale]

It's possible to buy replacement ball-bearing collet closer nuts for ER spindles. Arc Euro stock them, as an example. I use these on a couple of different ER collet spindles in my workshop, including the ER20 spindle on my CNC router, and they make tightening the collet much easier.

[JOGARA]

What type of spindle/collet?

If it's ER, then it sounds like you're not tightening it enough. ER collets have to be tight or bits will pull out. There are torque settings for standard ER collet nuts, but typically it's as tight as you can get it with your hands and standard sized spanners, however that's assuming things are well anchored. On a freely spinning spindle, gauging tightness can be a bit tricky.

It is the standard Chinese 2.2Kw one you can grab off ebay for a couple hundred.
ER20.
Ill try it a lot tighter then.

Is there anything I can do to the bit or the ER24 collect light rough it up a bit to get some more grip out of it?

It's possible to buy replacement ball-bearing collet closer nuts for ER spindles. Arc Euro stock them, as an example. I use these on a couple of different ER collet spindles in my workshop, including the ER20 spindle on my CNC router, and they make tightening the collet much easier.

Ill take a look, thanks!

[JOGARA]

Just ran the operation again and I think the same thing has happened again.
Not had a chance to measure yet but it looks like the bit is about 1mm lower than it should be.

Will report back soon


[edit]

Yep, 1.15mm drop on the bit.

Ordered the "ER20 Collet Nut with Ball Bearing - Type A - M25x1.5 Thread", hopefully that is the right one and works...
I also went through all my stock with this problem -_-

[Chaz]

Just ran the operation again and I think the same thing has happened again.
Not had a chance to measure yet but it looks like the bit is about 1mm lower than it should be.

Will report back soon


[edit]

Yep, 1.15mm drop on the bit.

Ordered the "ER20 Collet Nut with Ball Bearing - Type A - M25x1.5 Thread", hopefully that is the right one and works...
I also went through all my stock with this problem -_-

It would be nice if you replied to PMs about the RFQ you posted.

Thanks

[JOGARA]

It would be nice if you replied to PMs about the RFQ you posted.

Thanks

Thought I replied to everyone. Did I miss you?
If so sorry. Update on the whole thing, we are going to try and machine them here, if it does not work we will continue looking at quotes.

[Chaz]

Thought I replied to everyone. Did I miss you?
If so sorry. Update on the whole thing, we are going to try and machine them here, if it does not work we will continue looking at quotes.

Yep, didnt get any response. No problem.

The STLs you provided were out of scale too, they dont translate to workable CAD parts. They can be converted but Fusion refused. Its better (for future) to export to something other than STL if possible (Step / IGES etc).