Messages

111

General Mach Discussion / Re: Mill or Turn?

« on: May 22, 2019, 03:30:24 PM »

A short video of some tool paths to create the part shown in my original post.

Does it look like it might work or i need to change something ?

The tool is only 1.5mm wide.

https://youtu.be/J3ZCPnOwcrs

112

General Mach Discussion / Re: Mill or Turn?

« on: May 22, 2019, 02:23:45 PM »

Yeah, pretty much.

Covers next but need to sort out why the bearings get so hot first.

Maybe too much preload, not sure.

Using deep groove balls which i know is not ideal but they do have a rating for axial loads and the radial load rating is off the chart for a spindle.


Fixtures not so important as it only takes a minute or two to tram-in.

113

General Mach Discussion / Re: Mill or Turn?

« on: May 22, 2019, 10:39:55 AM »

Finally got some results i like. 

Pic attached of a little test part, diameters requested were 11,14,17,20mm results i got were 10.97, 14, 17, 20 so it seems accurate enough i think.

Short video...
https://youtu.be/AlcihBYrKIA

After the facing cuts, the first few passes are blank because the stock was 1mm under size (running out of junk metal) 

Birds nest at the end as well, lots to learn.

Next up is the multi-grooving/turning tool, see if it can part-off without snapping my tool.....

114

General Mach Discussion / Re: Mill or Turn?

« on: May 21, 2019, 06:40:55 AM »

Tried a lump of HSS and diameters came out as requested - best not to use cheap triangle insert tooling i guess

115

General Mach Discussion / Re: Mill or Turn?

« on: May 20, 2019, 06:08:23 AM »

Hi

yes the axes moves have all been checked and were all ok, all done with MDI moves, any backlash accounted for, but is minimal

I will do more tests when my cutters arrive, i do not like these cheap triangle tool holders, the bits are not located well and the fact i get different errors between two tools tells me not to trust the tool holders i think.

I have some SCLCR/CCMT and other shapes coming so will redo my tests when they are fitted.

116

General Mach Discussion / Re: Mill or Turn?

« on: May 19, 2019, 04:24:14 PM »

That's odd because OEMDRO 175 and button 324 also affect/update the tool table as well, that is not documented though it seems?

117

General Mach Discussion / Re: Mill or Turn?

« on: May 19, 2019, 07:48:34 AM »

Put a clock in the tool holder and command moves and see if the moves are accurate, going by your measurements I would say they will be but still worth checking. If in dia mode the clock will move half of the commanded movement.

As TPS has said centre height and orientation of the tool is critical for accuracy but it will only see small variances over small changes in dia so not likely your issue here.

Was your initial cut the same depth as your others?

Rigidity of your setup may affect things and thus setting up may require two passes to get right and doing the pass at normal DOC for a finishing pass is usually best on a set up with less than optimal rigidity

One thing to also consider with carbide inserts, it is often not a good idea to take a depth of cut less than the nose radius of the tool although it will depend on the inserts geometry as to how much it will affect things in doing so.

The depth of cut was variable, just pulling numbers out the air.

I have some more tooling on way, they use my favoured CCMT tips, the ones i'm messing with are more sacrificial and use triangle tips that i never really liked. I'll do some more tests when they arrive.

I'll also throw a DTI on there as soon as i get a gap this week, but i'm fairly confident it will be ok.

I did put a DTI on the quill when taking a cut to check for push-back etc but there was none, i also put some force on the quill by hand and again there was minimal movement so the quill looks pretty stable.

118

General Mach Discussion / Re: Mill or Turn?

« on: May 19, 2019, 07:45:10 AM »

just an idea, is your tool cutting realy in the Center of the spindle?

Yes, it faced-off with just the tiniest pip in the centre.

119

General Mach Discussion / Re: Mill or Turn?

« on: May 19, 2019, 05:27:08 AM »

Todays tests…

Tool was set by taking a random cut then measuring and entering dia into “touch X” DRO.

Next i requested a cut depth and noted the results, left is requested, right is result, error in brackets…

21.00mm = 20.69mm (0.31)
20.00mm = 19.62mm (0.38)
19.75mm = 19.47mm (0.28)
19.50mm = 19.23mm (0.27)

So the error is fairly consistent - 0.30mm would cure it, and it points towards the tool being set wrong by 0.30mm??? But how can it be wrong if i did a cut-measure setup??

Baffling me and clearly not right yet.

I tried another tool and got this…

21.00mm = 20.92mm (0.08)
20.50mm = 20.44mm (0.06)

These are more accurate but was setup in exactly the same way.
its a different insert shape tool.


Any ideas?

120

General Mach Discussion / Re: Mill or Turn?

« on: May 19, 2019, 02:26:15 AM »

Thanks Rich, got that.

Two things,

1 - This was one cut after the other - cut, measure, move, cut , measure and the second cut was off. I will re-test this today hopefully.

2 - Does anyone know precisely what the tool DRO's/buttons actually do - 175/176 & 324/326 respectively???