It's begun....

[Washout]

Thanks guys,

Its the federate that getting changed on clicking cycle start after a feedhold (I'll run it again today to see if there are any other indicators) - oddly enough it only does the slower federate for one segment of operation (I think more than one line of code is run through) i.e. if my tool path is say doing a profiling cut first and then 4 pocketing cuts in the corners of the part and I feedhold during say one of the corner pocketing operations, it will do only that one at a slow feed rate and then the next segment and onwards run normally (after a rapid usually). Its like MACH has determined there was a feedhold and resume and is being cautious on the resumed operation before going at the job normally.

I certainly have a G94 line in, as you can see from the header in the job here:

( Roughing Out 8mmEnd )
( File created: Thursday, November 21, 2013 - 02:40 PM)
( for Mach2/3 from Vectric )
( Material Size)
( X= 202.800, Y= 153.500, Z= 40.000)
()
(Toolpaths used in this file:)
(Roughing Out 8mmEnd)
(Tools used in this file: )
(1 = End Mill {8 mm} TC 2Fl)
N100G00G21G17G90G40G49G80
N110G71G91.1
N120T1M06
N130 (End Mill {8 mm} TC 2Fl)
N140G00G43Z5.000H1
N150S10000M03
N160(Toolpath:- Roughing Out 8mmEnd)
N170()
N180G94
N190X0.000Y0.000F800.0
N200G00X-40.947Y-54.860Z5.000
N210G1Z0.000F100.0

I'm figuring its something in the way MACH is setup, but can't find it.

Cheers


Chris

[Washout]

Hi All,
.
An update, a couple of pics and once Youtube has done its thing a video, which I'll edit into here with the link later.
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Firstly the pics below are a sub-frame mounting bush, which on the normal road car is an ali and rubber affair and in order to increase stiffness on the track are being replaced by these. This is just a roughing pass mostly - the finished bits being the counter-bored hole in the centre, the bottom half which is all 2D stuff and the M8 tapped mounting holes. So this is a bit of a milestone, as its the first proper part to come off of the machine apart from the L-shaped jig so the part can be flipped for 2 sided machining.
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The warts as I see them are a few ledges here and there where the machine lost steps, due to a bent ball-screw, which I am replacing, general chatter marks, which I should normally clean up with a finishing pass, but as this is going to be buried far from sight won't do unless my customer insists on paying extra for a run over with a ball nose mill ;-).
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Other bits I am intrigued about is the pretty pattern on the top which is very regular and I'm guessing is feed or speed related?
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Also once you guys can see the video, I am running what was to be a kind of pocketing pass to cut the part out, but it was such a faff I stopped that and just went for a slotting cut out path. Also the path you can see there hopefully shows the machine behaving nicely when slotting and chattering away when cutting on one edge (using climb is worse) and for info this is 6082 ali with an 8mm HSS end mill @ 10000rpm, 1mm DoC, 800mm/min and ramping over 10mm combined with a 600mm/min plunge (seems to be the sweet spot for my machine so far).
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The path was also being run after I had done the bore and two pockets, so there is a fair amount of air cutting going on, but hopefully shows a variety of behaviour.
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Once I have replaced the bent ball-screw and hopefully resolved the stalling/missing steps issue, I'm going to have to play about with the machine as the ease at, which it slots seems to indicate I should be increasing my step over when pocketing/profiling (currently 20% or 1.6mm) or increasing DOC, as the machine actually seems happier when going a bit more aggressive.
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I'm also exploring other CAD/CAM options, as whilst Vectric is OK, there are anomalies like the path in the video, which ramped on most, but not all plunges and driving the mill in the Z axis @ 600mm/min beats the snot out of the machine/tool, as does a too shallow or slow ramp for that matter. Having a teenage daughter could prove useful for a change, if I/she can get educational licences for stuff like Solidworks (I don't think SolidCAM do educational, as I would love to try their iMachining stuff) - its about time she started paying her way anyway ;-)
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Before I forget I have also got suspicious about the ZPA5-INT board, so for a few quid more have ordered a controller recommended by Dean in another thread (can't remember the name of it), so will report on that once I have it fitted and it looks like an almost drop in replacement for the current BoB.
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More when I get the time (Christmas vacation is almost upon me so hopefully not too long) and I have at least 3 more of these parts to make, so will try and get a longer video up next time.
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Later
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Chris

[EddyCurrent]

Are you using MIDI to control it and the mixer for analogue operations such as spindle speed ?

[Washout]

Now don't give me more ideas - I have enough bloody wiring stacked up to do on the machine as it is - hmmm thinks faders wired to feeds and speed control and hey its all XLR connectors isn't it? ;-)

[EddyCurrent]

I couldn't tell from the video if you had coolant/lube onto the work piece.

[Washout]

Yeah using cutting fluid at ~6% dilution through the airbrush - it seems to do the job cooling the tool, but makes the chips stick like the proverbial to a blanket and sods law mostly in the pockets/slots I'm cutting. I'm getting a new compressor this month with more PSI so hopefully that stuff will get blown out of the cutting path and probably onto the ballscrews/rails knowing my luck ;-)

[JAZZCNC]

Strange tool paths those it seem to cut more air than Chips.??

Your correct about step over being small and could possibly be why your getting chatter has not enough tool engagement. At those DOC you could easily do 50% thou I prefer 45%.
I would do some playing around in scrap with different DOC and STO etc and think you'll be pleasantly surprised just how much more aggressive you can be.!

[Washout]

Yes it is a bit strange as its a pocketing/cut out path which I was running after having done the two rectangle pockets. The idea being that the wider channel/pocket being cut would allow for chips to get thrown out.

Had my nerve held with the camera/phone, you would have seen it ploughing through more material once it got down to the level of the previous pockets, but I eventually ran out of patience and just went for a slotting cut-out and frantic brushing of sticky chips caught in the narrower slot.

I'll definitely being playing with some scrap to try some more aggressive strategies, as I agree the conservative approach seems not to be optimal.

More as I find time to play/work on it........

[Washout]

Hi All,
.
A quick text update and a shout out for a supplier (no I am not on commission, but credit where due):
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I have today rigged up a new compressor to my airbrush/mister solution and its a 50L Sealey unit SAC5030VE, which was posted in another thread - this thing is a breath of fresh air (pun intended) and with a blow gun will help considerably with chip clearance, which was one of my previous bugbears. Props go out to Sprayguns Direct, who I dealt with directly off of their website rather than their ebay shop and they delivered quickly and gave good comms/phone calls/emails throughout and threw in a more expensive blow gun in place of the one I ordered which they didn't have in stock...so credit where its due and we'll see how it handles long term usage.
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I have also got suspicious of the ZPA5-INT controller being a cause of some missed steps and other idiosyncrasies, so took a punt on an Optoport V3, which I'm hoping will be more reliable and I've literally just finished wiring this into my control box. Couple of differences on that board I hopefully haven't fallen foul of are that it needs a 15-70V power source, so have taken a feed off of my main transformer (68V) and also it only has one Enable connector which is wired to all the drivers in parallel and also doesn't have any pins associated with it. I have therefore disabled all the enable pins in MACH3 and redone all the pin mappings for the Step and Dir Outputs. I'll test this tomorrow and feedback on results and see if it is any better.
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Oh in my other post I alluded to ballscrew misalignment and finally tracked down an issue on my original X Axis ballscrew, which has been there since I originally put the machine together i.e. a piece of extrusion in the hole on the gantry sides, which whilst not preventing that ballscrew turning, was causing some binding - it now turns freely and smoothly by hand so should be much better generally.
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I am also about to rectify any inaccuracies in my manually marked, cut and drilled Z Axis, by machining two new plates, whilst at the same time replacing the old and probably "weak" spindle mount plates with one of those linear bearing blocks, which have the 80mm bore once the bearing unit is removed (can't believe how cheap that was compared to some components).
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Anyway more posts, pics and vids inbound once the machine is running again and cutting stuff.....
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.
Chris

[Washout]

Hi All,
.
Quick update and a pic:
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Over the last week I have been retro-fitting my machine with the new spindle mount using the 80mm bore bearing block I have had for a while now. As I also had some stalling issues on the Z-Axis I wanted to replace the manually marked and drilled axis plates with new ones and used the machine prior to dismantling to machine these out - making CNC is a lot easier when you have CNC obviously ;-)
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So here is a pic of the partially assembled new z-axis with its new spindle mount. I have to fettle the rails/bearings a little before locking them down, but given the two halves slid together easily, the alignment of the drilled holes etc. on the machine is a lot more accurate than the MKI eyeball I used previously.
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I also discovered when disassembling the axis that two of the SBR16 bearing blocks were loose and may have accounted for some of the chatter I was getting and may also be evident in the pic on the edges of the plates.
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I will hopefully have some video once the axis is remounted.
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Cheers
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.
Chris