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Are their any downsides to Dynamic Milling?


monkeyman
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A few weeks ago I started programming for a new shop and their programmer is really against using dynamic tool paths. He seems like he has a lot of experience programming. But It really seems like he leaves a lot on the table as far as speeds and feeds and not wanting to use dynamic cutting. When I ask him about the tool paths he insists dynamic is unnecessary and will wear the tool out more. That doing light depths of cuts quickly is more ideal since you can move faster. Even running simulations I'm able to prove that it's false and every documentation I've read said tool wear is more even and less harsh in the corners with hsm. I only have about 6 years of programming under my belt compared to his 9 or 10. He also has a reputation for going threw endmills pretty quickly. 

 

The machines they're using are haas mills that aren't very old. 

If any, what would be the drawbacks of using dynamic tool paths?

Can cutting using a HEM technique put more stress into the part causing it to warp more than light DOC?

 

Should I just keep my head down and program my own style and let my parts do the talking? 

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"There are no perfect solutions, only trade-offs." Thomas Sowell

If done properly, HEM toolpaths are a better method to remove material in most machines under 5 years old. Machines over 15 years often can't handle the amount of data generated by modern toolpaths unless they came with high speed RISC processors and were tuned. 

Newer machines are designed to take advantage of these new toolpaths.

JM2CFWIW 

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6 hours ago, monkeyman said:

Should I just keep my head down and program my own style and let my parts do the talking?

This has been the way I have approached programming for the 20+ years I've been doing it, and I have had increasing success throughout.

Except for the, keeping my head down, part. F that sh*t. I hold my head up and stroll through life happily, Humility is one thing, cowering or submission are quite another.

Dynamic milling is a fantastic tool in your programming toolbox, to reject it out of hand is, IMHO, negligent & a little foolish.

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Unless all you're doing is facing-style or roughing cylinders down to smaller cylinders, any form of Dynamic/Adaptive/etc. toolpaths will put less stress into the work piece because you'll never overload the tool like you do with a classic pocket-style roughing.  If you think about the physics of what's happening in the cut, with a dynamic toolpath, the tool is always going to see a constant load under full cut because it's peeling into any corners.  

With a classic pocket-style, if you're machining a square out, every time you go into the corners you go from, say, 30° of tool engagement to all the way up to almost 180°.  Cutting pressure increases exponentially, so you're talking hundreds to a thousand times more tool load in that instant until the flutes cut the material away.  That's why you get that squeak in the corners.  That load is also work hardening the material and stressing your workholding. 

That's why tools can remove so much more material before failing using Dynamic, there's never that "shock" that chews up the edges.   Plus you wear out all of the flute length evenly.  Less shock loads into the material means that deformation is minimized and more predictable, and workholding often times doesn't have to be as aggressive, or at least, you can turn down the pressure if you can't clamp as well.

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The downsides are as James mentioned that some machines struggle to maintain good movement with the volume of code that Dynamic can produce.  In those cases, make sure you filter it, and that your minimum radiuses are big enough to maintain your feedrate.

If you have a soft material that won't overload the tool, and you can do do your roughing in one depth with the traditional style, Dynamic may be slower in those situations.  They're generally rare, though.

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One last thing to recommend if you haven't checked it out yet is HSMAdvisor.  This isn't a paid promotion by any means, but I'm just a satisfied customer.  It will help you get in the ballpark really quickly to make sure you're really utilizing the proper feeds & speeds in HSM style cuts.

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9 hours ago, monkeyman said:
Can cutting using a HEM technique put more stress into the part causing it to warp more than light DOC?

Not in my experience, but really going to come down to the material, the part and the work holding before I would say that with 100% certainty.

9 hours ago, monkeyman said:
Should I just keep my head down and program my own style and let my parts do the talking? 

Each of us have to decide the path and direction that works for us. I know of 20 places right now that would love to have someone with your attitude working for them. Willing to think out of the box and looking for ways to improve the bottom line is what every programmer should be thinking about and doing in my humble opinion. I think every programmer should be the CTO(Chief Technical Officer) for any place they work in. I have known how to select my own tools, holders, design and make fixtures and setup and run just about every machine I have ever programmed for when I was working in a shop as a programmer. Before I went out on my own as an consultant I had worked in 40 different shop over 24 years. i was always running my mouth saying I could do it better and faster. Not that I always did that, but majority of the time I have always done it better and faster. You have to have faith in the abilities you were blessed with. Don't be arrogant about it, but sometimes confidence will be perceived that way no matter how humble you try to be. I have always tried to teach and help others through my years. Give back to others and it will help you get better at your job. Hold it all in and not be willing to admit when your wrong and you will only get so far.

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It's so wild to me that this topic was brought up this week; literally two days ago I had the typical know it all type criticize the way I approach my programming by utilizing the dynamic and the new toolpaths in Mastercam. I did my best to defend myself, making similar arguments that were brought up here. But perhaps because of my age or only having 5 years experience he was blinded to my rebuts.. So it feels really good to know that I'm not off base in my thinking. I'll probably even print this thread out and hang it on the wall for the next "back in my day" micromanaging meeting 😅

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7 minutes ago, Jespertech said:

It's so wild to me that this topic was brought up this week; literally two days ago I had the typical know it all type criticize the way I approach my programming by utilizing the dynamic and the new toolpaths in Mastercam. I did my best to defend myself, making similar arguments that were brought up here. But perhaps because of my age or only having 5 years experience he was blinded to my rebuts.. So it feels really good to know that I'm not off base in my thinking. I'll probably even print this thread out and hang it on the wall for the next "back in my day" micromanaging meeting 😅

One of the biggest benefit that people forget about with Dynamic vs. classic Pocketing is predictability.   Because Dynamic-style paths are completely agnostic to the input shape, if you find your tool lasts X amount of time cutting Y material, it will always last that long, regardless of the shape you're cutting.   With a classic style toolpath that just offsets the shape, how long the tool lasts (and work put into the part) will vary based on how many corners there are in the pocket. 

For example, cutting a triangle is the worst scenario, as your tool engagement in the corners will be horrible.   And every offset pass, your tool has to go through those three corners.  A rectangle is slightly better, as the corners aren't as severe, but there's still four of them every offset, etc.    Hexagons are slightly better, etc.

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Not every path works in every situation on every machine. There is no one size fits all argument for HSM tool paths. 

Having said that, that guy sound a little ignorant and stubborn.  I guess that rejecting those paths is his loss?

10 hours ago, monkeyman said:

Should I just keep my head down and program my own style and let my parts do the talking? 

Will you get in trouble if you do?  If not, and you're confident in your approach, who cares what he thinks?

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I you're running X5 to X7ish I would agree with him but with any version from 2017 and later I would definitely be dynamic milling and let the operators do the talking. I know nothing about Haas but since they acquired space on the IMTS main floor they went from a bunch of rattling pieces of junk to more normal sounding machines.

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5 minutes ago, Tim Johnson said:

I know nothing about Haas but since they acquired space on the IMTS main floor they went from a bunch of rattling pieces of junk to more normal sounding machines.

Bubble gum and duct tape perhaps  :D

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2 hours ago, Jespertech said:

It's so wild to me that this topic was brought up this week; literally two days ago I had the typical know it all type criticize the way I approach my programming by utilizing the dynamic and the new toolpaths in Mastercam. I did my best to defend myself, making similar arguments that were brought up here. But perhaps because of my age or only having 5 years experience he was blinded to my rebuts.. So it feels really good to know that I'm not off base in my thinking. I'll probably even print this thread out and hang it on the wall for the next "back in my day" micromanaging meeting 😅

I had a self proclaimed number 3 programmer in the world throwing me under the bus at SpaceX(Been more 5 Years so I can say their name) when I was onsite getting 3 Multus Machines for them up and running. I never made the first promise about run time or what I would get done. I came in and said give me 6 weeks to see what I can do, I will do my best and at the end of 6 weeks you can decide if I am bringing value. This programmer was sending anonymous emails to the President about how I was ripping them off not doing my job. She came through the area without asking one question and I needed to document the work and justify why they were paying me to be there. I sat down and did the ROI on the 3 parts I was working on at the time. Part #1 was a 40 hour run time on 4 different machines reduced down to 4 hours and one setup. It was saving them $1.2 million a year in Manufacturing costs. Part number 2 was 100 hours and 10 different machines with an outside process of $750 per part that took 6 weeks to gig grind the parts. The run time was reduced to 12 hours and no outside processing done in one setup. The saving was $2.2 million per year in Manufacturing costs. Part number 3 was 32 hour run time over 5 different machines reduced to 6 hours on setup. It was a 2 swap process where It start in the Main Chuck was swapped to the Sub then back to the main. The saving in Manufacturing cost on that part was about $800k. I think they had paid me about $18k at that point. I told them to forget what I was charging and hour and just give me 10% of the savings. I did work for almost 5 years for them before we parted ways on very bad terms with them not paying me for 400 hours of my time. I don't share that like I am anyone special because I am not, but even with 35 years experience doing this I get the same type of thing going on also.

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The danger of the way it’s always been done…

 

As a sociological experiment, 10 monkeys were placed in a large cage. High up at the top of the cage, beyond the reach of the monkeys, were a bunch of bananas. Underneath the bananas was a ladder leading to the bananas.

 

The monkeys hadn’t been fed for 12 hours and were extremely hungry. The monkeys immediately spot the bananas and the strongest begins to climb the ladder. As he does however, a slight electric shock keeps him from ascending the ladder. At the same time that the monkey climbing the ladder gets a shock, the other monkeys on the floor are sprayed with water. The monkey on the ladder scrambles off and all 10 hungry monkeys sit for a time on the floor.

 

Soon, the temptation of the bananas is too great and another monkey begins to climb the ladder. Again, the monkey is met with a slight electric shock as well as the other monkeys being sprayed.

Over time, the monkeys learn not to go up the ladder.

Now one monkey is removed and a new monkey is introduced to the cage. Spotting the bananas, he heads towards the ladder. The other monkeys, knowing his intention, cut him off and beat him.

 

A second monkey is removed; he is one of the original 10 monkeys and is replaced with a new monkey. Again, the new monkey heads towards the ladder and, again, the other monkeys cut him off and beat him – including the monkey who had never been up the ladder.

By the end of the experiment, none of the original monkeys were left. Despite none of them ever experiencing the slight shock, they had all learned not to climb up the ladder for the bananas.

This story shows the impact of what we call “Cultural Training.” Often, a new employee is trained by another “experienced” employee; but not from a Known Standard, SOP, or Work Instruction. Usually the “Experienced” employee is expected to mentor and pass off years of experience in a short amount of time (usually days or even hours). The new employee is taught what the previous employee defined as “the standard.” The new employee, not remembering everything he is taught after the experienced employee leaves, has to survive by developing what he thinks is the process.  Over time and generations of employees, the original “standard” morphs into something very different than the original “process.”

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On 5/18/2022 at 11:17 PM, monkeyman said:

If any, what would be the drawbacks of using dynamic tool paths?

Be careful with "dynamic contour"... If you use the finishing path. It ignores the min. toolpath radius and plunges thru material that it just finished carefully leaving out of the path! Still !! after years of rereleases !

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11 minutes ago, Seedy steve said:

Still !! after years of rereleases !

We have request #R-14452 logged to add support for a separate min radius for the finish pass."

That has been on their agenda since  January 2019!!!

maybe it is good in 2022? I doubt it.

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On 5/19/2022 at 8:56 AM, crazy^millman said:

I had a self proclaimed number 3 programmer in the world throwing me under the bus...

:rofl:

What kind of person makes such an unqualifiable statement like that? Wow just wow. 1) Such a thing would be impossible to determine since there's probably well over a million (just taking a WAG here) CNC programmers in the world and there is no contest to determine it. What would the criteria even be? Fewest broken tools on a new program? Shortest cycle time? Fastest program generation? Most programs that run lights out? Even if somebody went to "Skills USA", "VICA" back in the day, etc... and placed or even won, that doesn't even really mean much. I know some serious programming studs whom I'm barely worthy to wash their coffee cups that would never lower themselves to even enter such a competition because their egos  don't need it, and they don't feel the need to make impossible grandiose statements about how good they are. The fact their stuff is in the deepest parts of the ocean, deepest parts of outer space, in people's bodies, in surgeon's hands and everywhere in between is good enough satisfaction for them.

Number 3 Programmer in the world... :rofl: :rofl: :rofl:

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43 minutes ago, cncappsjames said:

:rofl:

What kind of person makes such an unqualifiable statement like that? Wow just wow. 1) Such a thing would be impossible to determine since there's probably well over a million (just taking a WAG here) CNC programmers in the world and there is no contest to determine it. What would the criteria even be? Fewest broken tools on a new program? Shortest cycle time? Fastest program generation? Most programs that run lights out? Even if somebody went to "Skills USA", "VICA" back in the day, etc... and placed or even won, that doesn't even really mean much. I know some serious programming studs whom I'm barely worthy to wash their coffee cups that would never lower themselves to even enter such a competition because their egos  don't need it, and they don't feel the need to make impossible grandiose statements about how good they are. The fact their stuff is in the deepest parts of the ocean, deepest parts of outer space, in people's bodies, in surgeon's hands and everywhere in between is good enough satisfaction for them.

Number 3 Programmer in the world... :rofl: :rofl: :rofl:

He didn't know how to program the machines I was in there working on. He knew 5 Axis programming, but not Mill/Turn. I was using an inferior software to program with in his mind. He is a NX snob and me using Mastercam makes me a second rate programmer. Funny the head of Purchasing had instructed the purchasing department to not send 5 Axis work to shop using Mastercam. When he found out our group was using Mastercam to program their parts and heard what we were doing he called me and I told him yes the rumor is true Mastercam can program any machine you have. They changed their policy after that conversation.

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11 minutes ago, crazy^millman said:

... Funny the head of Purchasing had instructed the purchasing department to not send 5 Axis work to shop using Mastercam. When he found out our group was using Mastercam to program their parts and heard what we were doing he called me and I told him yes the rumor is true Mastercam can program any machine you have. They changed their policy after that conversation.

Two CAD/CAM/CAE/PLM companies shovel this kind of bullshiite; Siemens and Dassault (CATIA). Why? Because their CAM product is inferior to probably half a dozen CAM packages out there and they are embarassed about it. So, they peddle lies to their customers in hopes their inferiority won't be exposed. Their CAD/CAE/PLM packages are excellent however... CAM... not so much.

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