CAD/CAM discussion forum > 3D CAD/CAM > RETRACT LIMITING

RETRACT LIMITING

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george

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Registered: 2004-3-1

Message 1 of 10

 RETRACT LIMITING
15-04-2004 03:19 . pm | View his/her posts only
Doe anybody know of ways to keep VX from retracting so much? I am using quickmill operations such as rough offset 2-d and z-level finish to name a few.

Also I am not getting as good of a finish as would like. Any tips would be a big help.

Thanks

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ChrisWard2k2

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Registered: 2011-11-22

Message 2 of 10

16-04-2004 09:51 . am | View his/her posts only
George, we are going to need more clues about the shape you are machining in order to give best advice on retracts, but QuickMill HSM operations focus on keeping the tool on material. Dr Dan gives some very good advice concerning general choice of strategy on this forum, see the link "QM Some suggestions of how to choose and present toolpaths to the potential clients".

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Dan

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Registered: 2002-8-26

Message 3 of 10

16-04-2004 09:52 . am | View his/her posts only
QM can be instructed to retract in very few ocasions.

If you read the forum post:
QM New psychedelic HSM Short Links for Roughing

You'll see how the linking can be done in new QM's(V0.20.10 or upper) and VX(V9.5 and upper).

In current QM you can use bigger Short Dist Factor to convert some of the undesirable long links to short one and apply smooth short linking.

Another trick is to do not angular limit Z level. I recommend to use in less than 10% of the cases angular limiting for Z level this fragments the part terrible and really isnt software weakness here. If you have forged parts this usually doesnt benefit too much from Z Level angular limiting! If you have a bothering part post it and Ill analyze it for you maybe is something we can improve in QM.

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Dan

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Message 4 of 10

16-04-2004 09:54 . am | View his/her posts only
Yep Chris I know the Guy (DrD) personaly and he post here gazillions (where a gazil > 3) of tips of how to do the magic trick

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george

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Message 5 of 10

16-04-2004 01:34 . pm | View his/her posts only
Could you take a look at this file and give some tips on limiting and look at the surface finish, when we cut this the contoured walls are pretty choppy looking the straight part of the walls look decent.

Thanks

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Dan

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Registered: 2002-8-26

Message 6 of 10

19-04-2004 02:56 . pm | View his/her posts only
Many, many not too recommended techniques used:

1. First the main roughing is done with surface thick = 0 and 0.04" tolerance = recipes for disaster! The surface thick should be at least twice as big as tolerance in roughing to avoid any kind of problems! Pretty much this destroys everything converting the final tolerance to 0.04" = 1 mm that is very, very coarse surface thick must be at least = 0.1" = 2.54mm.
2. All other rough paths uses 0.01 this is a glimpse of reality should be 10 bigger to avoid any problem.
3. All roughing paths except first doesn't have the stock specified that's bad because for complex stocks rest roughing and AFC can't figure out how to correct mill the part potential breaking the tool.
4. Tolerance = 0.0005 with surface thick = 0 in finishing cycles. That's revigorating to see when the surface was "destroyed" by first roughing path.

I anyway took action to set by default Tol = 0.004" and Surface thick = 0.04" as specified in the initial spec.

Luckily how Chris well pointed you can read the forum and isn't necessary to invent numbers. Reading: "QM Some suggestions of how to chose and present toolpaths to potential clients" some thing can be read in other previous posts too with slightly variations.

Roughing, in general, has the same tolerance and same surface thick and same Z Step! In general is ok to use intermediary steps for main roughing if you use them then the real Z step is ZStep / (Number of interim steps + 1)
Surface thick is at least 2 x tolerance!

Finishing tolerance is as required here no suggestions at all.
Finishing in general has the same Surface thick = 0, Tolerance = 0.01... 0.0005mm, and same cusp height (!!) = 0.01... 0.0005mm. This isn't visible in your rest finishing operation that uses other value than cusp height setting.

Now regarding the pretty masochistic way of using offset 3D to finish this part. I'm really impressed about QM ability to generate such a beauty (so I like a lot what I'm doing ) but this isn't the recommended way of semi-finishing and finishing this part milling is too long and Z level gives you more control in regionwise milling than Offset3D.

I recommend OR the blind good recipes: "1 SideCut + 2 (HSM)Lace OR offset 2D in flat places. (75% of cases)" OR, being aware your part is in forged or technical parts category, you can use: "1 SideCut + EqualCusp (general technical parts). (20% of cases)" so pick one and the path will faster generated with same desired cusp height and tolerance. What is between quotes is again from the same post: "QM Some suggestions of how to chose and present toolpaths to potential clients"

Rest finishing again nothing to complain is ok and I recommend only offset 3D for it in very few occasions Z Level + Offset3D. Are some wobbles on top you can extra remove them if you are on the very picky side of the balance making a bigger min rest height and a smoother analysis. I saw you had moved the slider in smooth direction

As a methodology I always recommend milling in 3 stages this kind of parts roughing, semi-finishing and finishing read (again) the same post that explains how to set parameters and what kind of paths to use this is how many clients mills and they have remarkable successes in achieving quick mirror like surface finish with QM in very short generation time.

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george

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Registered: 2004-3-1

Message 7 of 10

19-04-2004 03:58 . pm | View his/her posts only
I am looking things over, when you refer to the surface thickness as being twice the tolerance setting you are using mm as an example, are those settings in metric or inch? I have VX set up as inch but I have seen instances where it still refers to metric. I have also noticed when I use quick mill roughing operations it leaves differing amounts of stock on surfaces this has lead to broken tools because there is too much stock left from roughing.

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Dan

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Registered: 2002-8-26

Message 8 of 10

20-04-2004 07:37 . am | View his/her posts only
QM leaves stock = surface thick +/- tolerance + stairs size due to Z Step this is how it must be if is something that isn't like this then we must fix it and please don't hesitate to let us know.

To correct your part you can go down in Z direction 0.5mm (if you can afford) and start milling again finisihing and rest finishing this should fix surface quality problem I'll be happy if you can do this and isn't necessary to throw the part.

In general i speak in mm and twice means twice in both metric or imperial. Always leave stock in roughing in semifinsh because keeps better tool engagement and results in better surface finish.

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george

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Registered: 2004-3-1

Message 9 of 10

21-04-2004 02:20 . pm | View his/her posts only
Can you put cutter paths on the file that I posted the other day, I would like to see how you would go about machining it.

Thanks,

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Dan

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Registered: 2002-8-26

Message 10 of 10

21-04-2004 03:26 . pm | View his/her posts only
I will put if you want. But your part is pretty big and requires some time to upload and download and I'm pretty much pressed by time these days. I dont know if your part isnt a company secret and we can post it in public places like this forum.

And putting paths without knowing your milling conditions (material, tool set, machine, final cusp height, tolerance, etc) will look a little bit naive so would be better to contact our support in this regard.

I told you if you run on you part the last 2 finishing operations moving half mill in down direction it will give reasonable surface finish.

The paths are generated both at reasonable milling conditions only the surface was knocked by the lack of surface thick during previous rough operations.

--dan
See also