Making Accurate Parts on a CNC Lathe: Dealing with Thermal Growth!
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- čas přidán 20. 07. 2024
- Thermal growth affects part accuracy and repeatability way more than we realized. If you have tooling, workholding, and toolpaths dialed in but still have trouble with accuracy and repeatability, it may be related to thermal growth. Let's talk about the importance of thermal stability, how slight, sudden changes in machine shop environment can blow tolerances, and how to use NC programs and variables to keep the lathe at the right temperature before parts are made!
00:00 Intro
00:30 The Importance of Thermal Stability for Accuracy & Repeatability
01:40 KERN & High End Machine Builds to Control Thermal Growth
02:13 Controlling Machine Shop Environment & Other Considerations
03:32 CNC Machine Warm Up Routines
04:39 Parts Application, Fusion 360 NC Program, SMW Diamond Pins
05:15 Tool Probing, Updating Wear Offset, Coolant Temperature
07:19 Spindle Liners, & Sandvik Finishing Insert
08:44 Incorporating Code Into Machining Process to Control Temperature
09:54 Outro
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Links for this video
Code Snippet on NYCCNC: bit.ly/2S5rnNZ
Nicholas Hacko Watchmaker: bit.ly/2zU3Cgk
KERN Tour: bit.ly/3ev6OBW
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Reach us / CNC Info:
Speeds & Feeds: provencut.com
Download Fusion 360: www.dpbolvw.net/click-9255839...
Online Fusion 360 Training: bit.ly/LearnFusion360
SMW Products: saundersmachineworks.com/
CNC Resources: www.nyccnc.com 5 Reasons to Use a Fixture Plate on Your CNC Machine: bit.ly/3sNA4uH - Věda a technologie
John, this is gold. One thing though, you are now on a level to consider going into more all those quality management/ quality methods commonly used in the industry. SPC for example, iso certification, FAI etc.. This might open up the next level for you and your company! Keep growing! Great to see how your tinkering with the taig in the bedroom eventually turned into a full-fledged business on par with any ou there.
It's amazing how much thermal stabilization affects things. Where I work, we have specialized video projectors (some of them worth just under $1M each). They have custom lenses on them (each lens is just under $100k each). We've found that we cannot adjust focus until the projector has been running for at least 30 minutes because the heat of the light passing through the lens will change its properties. If we focus cold, it will be out of focus when warmed up.
I love your dedication to detail for excellence and then consistent excellence. Thank you.
This is something I learn't pretty quickly. The lathe I work on takes about 2 hours to warm up and consistently hold size. Every part I run for the first 2 hours I need to move the tool wear offset -0.01mm every part I make (usually around 20min cycle time) to keep size. Checking mics is very important too. Always check them in a controlled environment using master rods and take the difference into account when checking each part.
This is very true. I almost never see anyone talk about checking the tools used to measure down in the tenths, 0.0001. The tools need to be checked routinely as well and be thermally stable, just as the machine need to be. It is a whole process when dealing with tight tolerances.
Precisely. We have what we call a “Standards Room” in my place of work which is kept at a consistent 20 degrees celsius all year round. It isn’t allowed to be a degree out. This is where all inspection equipment is kept when tight tolerances need to be met.
That is a lot I worked on Okumas they are top no Change what so ever
So true, few years ago i was working on titanium dental implants production, where we had some tolerances about 5-10 microns. Temperature was everything, you don't want to stop your lathe at any cost, you will hate the one who opened a window in the far corner of the shop, expecially in winter and if you out of tolerance, its easier just to make offset changes while making some flaw parts running instead of stopping machine for couple of minutes to realise that almost all of your tools moved on x axis for a dozen of microns sideways ;D
When I worked with Cnc lathes, I used to make a part that had a 7 degree taper to it. The heat of the machine really magnified the error in the taper. Normally the first 50 parts have to be constantly adjusted, and after that it’s stable for the rest of the run
Interesting information. Its generous of you to share your lessons learned..
True. As a machine tool testing company (Advanced Machine Tool Testing Facility - AMTTF), We tested several machines for its thermal growth, even for a ambient change of ±4 deg C , the Tool center point shift was observed 60-80 microns.
I loved this video. I literally dealt with this today boring a .4997/.4999 hole on my mid 1990s Daewoo Puma. Knowing the machine and how much it moves is important. Once you get it warmed up it will hold dimensions all day. The problem is it takes quite a while to get everything warmed up.
LOL.
Yes it can be a bit of pain If you choose to warm up a machine for accuracy.
Either that.
Or chase your numbers until everything settles down. ????
It does depend if it's your machine or you just run that machine
Simply said.
A boss wants product asap.
They have not much care for you stuffing around adjusting things while your pulling your hair out. 🤣🤣🤣
Another good video for me! Very relatable right now.
Thanks for doing videos! Much appreciated!
I know Kern goes crazy on temperature control but it pays off in repeatable accuracy. :)
This is also true in 3d printing surprisingly enough, a machine that a machinist would laugh at with tolerances and you can get a noticeably better part when you let a machine heat soak at its printing temps
Thanks for the tips they are much appreciated!
We installed a very long bedway grinder.
It was setup perfectly. Came Back to re check it a couple of days later and it was out again. So we re adjusted it. We repeated it several times and we couldn’t figure it out.
It actually was the tide that threw it out.
So we had to settle on a average Setting. It’s always been within the tolerance but we and the customer wanted it better but finally decided to settle on good for most conditions.
And we’re talking about microns.
Setting it up was done with piano wires and autocollimators
Very interesting fact. Shop is relatively close to the ocean.
Very interesting what weird things can influence
There's a place in IL that one of my teachers in a shop class told me about. They had issues holding insane tolerances on some of their machines and couldn't figure out why. It turns out it was semis rolling down the highway like 200ft away. They then completely isolated a section of their place just for inspection, as in, concrete wall, filler, THEN the foundation.
Thanks for the video. We are working with wood where temperature and humidity have significant effects on the outcome.
I had a job many years ago where the machined diameter had a total tolerance of .000075" And this was because the part had a +\- .00025 tolerance after plating. and plating tolerance was +/- .0005". Ran part on a Daewoo Puma 240MS. That machine was extremely accurate... The shop I was at only turned the machines off for the weekends
I'm a home shop guy learning on a Clausing 5900 and have a small Emco PC-Turn 55 CNC lathe I'm converting. Hearing these tolerances makes my head spin. If I can get within a thou I'm doing a jig.
Love the content, maybe try less cuts? Its a bit jittery.
Strong Max Headroom vibes!
This has to be some nvidia ai for John, right?
Really good video
unless otherwise specified, all dimensions and tolerances are applicable at
20 deg.C.(68 deg.F.) in accordance with ANSI B89.6.2
compensation may be made for measurements at other temperatures.
John, why not have it call up the spindle warm up program for the certain tools and then looping back to the main program if it is not warmed up yet, instead of the m30? That way you don't have to manually run the spindle warm up each time, and then change programs back to the part program. That way you load tools, start the program, and if it's not warmed up, it runs the warm up, if it is warmed up it runs the part.
Good stuff! Why not add in the quick warmup routine into that loop? Cycle start and it runs the warmup loop until its past your temperature threshold, then starts the cut w/o extra operator input?
Good idea
Love it
Could you use some sort of spring-loaded bearing spider to hold the incoming stock rods centered?
Here is a thought. Why not use those variables and program it to run or skip a warm up based on the temp. This way the you are not counting on the operator to pick the right program to run. If temp less than X do warm up 1, between X and Y do warm up 2, Above Y run program. This way if the machine sits till an operator can get to it and it has cooled down, the machine will not run parts till it is at temp with the self check. I use macro programs like this to change the cutting parameters of my tools based on the parts counter for the bar in the machine. It would be a very similar program.
Using Macros is such an underrated skill!
You could alarm rather than M30 so someone doesn't think the part is finished and put it in the "Good Bin" and start the next part off.
(Ensure spindle is warm)
#605 = #13009
IF [#605 GT 680] GOTO123;
#3000=1 (Temp too low)
N123
I’m running a nakamura as200l and it has about a 0.0015” warm up in the x axis. I try to do the setups with the machine cold so I’m not chasing dimensions. Then let it run in memory restart cutting air for about 4 cycles (26 minute cycle time) and it will be ready to rock. Will hold a 0.0001 all day long.
Weird seeing Haas be actually decent at something. I always see them as just a backmarker in F1. :P
Irony being their lathes are horrible
@@mannycalavera121
It's a shame because there controllers are great to work with.
I guess you just need to be mindful of the limitations of any machine.
HAAS machines are generally less expensive than others for only one ?? reason.
@@weldmachine I have 4 Haas machines, I don't particularly dislike them and you're right, their controller are a selling point. Bit tbh the lathes are just not up to par with the likes of Doosan for the same money
@@mannycalavera121
I would Definitely buy a Doosan well before a HAAS machine.
Especially like the option of a Siemens Controller.
Would you consider 100 degrees a good number? In Phoenix that's a normal day. In your neighborhood you would have a lot of 32 degree days. in which would be the difference between cold and warm days. That's a big difference. The hottest that I have been in is 125 degrees. The coldest my A/C would get was 85 degrees on that day. Thank you for your time.
just curious why you would not have it run a warm shorter warm up cycle with a loop until it hits a desired temp (ex. if spindle temp is lower than (value) go to #(value) and it runs a loop of warm up, then checks the value again) and have it do this till machine is hot, then you don't have to run the cycle manually. seems like it may help production because it automates your process more.
Very helpfull
Can you confirm that the thermal compensation is power on time based as the Haas has no sensors other than the electrical cabinet?
Hi John, I saw on 8:59 of you diagnostic screen that's your DC voltage is low. It shows DC voltage of 310 Volts which is on the low side (310-360 V). Do you have any electrical issues?
WOW.
Well spotted.
Now i need to watch that part of the video again 🤣
Used to run Hyundai HIT-30 lathe. From 07 00 to 12 00 I'd be changing offsets. From 1200 till 15 00 it would hold microns
LOL.
CNC anything always run like this.
As the temperature rises in the morning it can play havoc with tight tolerance parts.
You look strung our john take time for your self
Please share your Warmup routine code?
It's a bit of a pain working at night.
But this is generally the best time to run tight tolerance parts.
The temperature at night time is more stable than daytime temperatures.
And those odd saints keep the day-shift productive. (When we're not blaming them)
@@mitchradoll278
Yes.
Definitely a lot of rivalry between Day shift and other shifts working in the same shop.
The blame game is Never ending 🙄
Coolant chiller also keeps the part to size,, the larger the part the more it is effected.. 68 degrees dont machine your part at 74 degrees then come in tomorrow after he part acclimates and have it shrunk below tolerance.
Just have some Heidenhain scales on your machine, takes out most of the thermal expansion and ballscrew inaccuracies/backlash....
My dad was a machinist my entire life I'm a welder by trade but I really want to get into a shop
Buy a mazak and you won't have thermal growth. It's a Haas what do you expect. We turn on our machines and the whole day we hold tenths. No matter what temperature the shop is. Mazak runs coolant through the ball screws. You done even need to warm the machine up.
I always wonder, how accurate is the "clock" of a cnc machine? I mean literally all the cutting functions of a cnc machine basically relies on time itself. Sure it can spin at so and so revolution in a minute, or move so and so inches in a minute. But how accurate is that 1 minute exactly?
Is it possible to have a mathematical constant included in your gcode to add an offset in depending on temperature? Material expansion should be consistent for the material, and it should be possible to plug the thermal expansion coefficient into a calculation to adjust offset, on top of tool wear offset.
Many controls have a math language to add calculation to the gcode, but it's different for each controller brand, and most posts don't generate any math. I guess you can write your own post, too?
In my experience, every tool reacts differently to temperature swings, so this thing would be useful for big amount of parts only.
Want problems do work for a shop that doesn't have a proper inspection room that checks the parts you made at some broadly different temp then complains they are out of spec. :-(
Okuma machines have built in sensors.
HAAS machines are generally cheaper for a reason.
Just a case of knowing the limitations of your machine.
Whether it be a Manual or CNC.
@@weldmachine I know all about their cheap makeup. It’s the shitty dealers and haas Corperation that I’ve learn first hand. It’s just like our government.
@@dford344
At least Gene HAAS is enjoying his life ??
I've got a huge question....here me out. So i got my NTMA Cerfication when i was younger and never worked in the field. How would i go about getting back into machining...? Serious serious question. I was so young and dumb back then....im super depressed
Maybe just find a Button pusher Job and go from there
@@MrKurdishFreak that sounds like a start for sure
What are you resources? Can you buy an old bridgeport and run some parts manually?
@@jonwatte4293 You mind clarifying that for me sorry im not understanding sir
@@hardhitt3r410 How much money and space do you have available? If you have "a few thousand, and a garage-like space," you could buy a cheap used manual mill, and take some local work for nights and week-ends (manually) to get back into the business. Then once you have some background, you can figure out where to go next with that.
If not, I agree with the others whosuggest getting a button-pusher CNC operator job to start out, and then see where you can go from there.
Just use a big chiller and it will be good
OR just use a tool probe and macro programs to adjust the parts through the 'tool wear' function after each part...
Would be chasing that all day with Mori. New shop has Okuma. And climate control. Just have to move tenths all day. Might move .002 all day but just increments of 2 tenths. Must be quite a tolerance if your chasing it that much.
The comp cuts for the audio are fine, but the fast video cuts are distracting. Maybe keep a single video track to put audio over? Or cross fade the picture?
I run a cylindrical grinder often doing match fitting and I can tell you that temperature really is key. Part comes out of the machine cold due to coolant so if you check the size right away you’ll have to add .00002 to .00004” to your size depending on how big the part is material type and so on. Having a climate controlled shop is very important.
Note to self, keep an aquarium heater in the coolant tank overnight. :P
That would just make the coolant a breeding ground of all kinds of nasty stuff. If you've never had serious dermatitis from messed up coolant, then count yourself lucky.
@@brandons9138 that sounds TERRIBLE.
As you're preparing for the deed in the bedroom:
"Babe, what's that rash all over your body?"
"Jus nappy coolant. Bacteriumz n' such. It's not contagious. Let's get it on."
@@shirothehero0609 When I first started as an operator I got a really bad case of dermatitis. The skin on my hands was literally cracked, bleeding and itchy. All because the coolant in the machine was old and the sump hadn't been cleaned in years. They had to put me in inspection untill my hands healed up enough. The down side was after all that my first day back on the floor they made me clean out the machine from top to bottom. Over the 15 years I've been in the trade my skin has gotten tougher. On shop I worked at I decided it was time to do a full coolant change over. I was appalled by what I found in the sump. It was a whit/grey/black mass about 4 inches thick in the far corner of the sump. I had to slice it up and shovel it out of the machine. It was the consistency of mayonnaise.
@@shirothehero0609 🤣🤣🤣 👍
Step one. Don't buy a Haas. Step two. AC the shop.
Wrong ...he explains why you don't need more than a Hass and with the money you will save you can afford to climate control your shop.
@@3markaw Lol. "Don't need more than a Haas." They are base level machine tools at best. At my last shop that wasn't climate controled we had several Citizen swiss machines that would easily hold .0001s all day from the moment it was turned on. All of the hoops they had to jump through just to do what other machines can easily do just proves my point. Haas has it's place in the industry, but they are commodity machines. Look at what Titan did with his shop. As soon as the aerospace work started rolling in he ditched his flimsy Haas machines and got better equipment.
@@brandons9138 When you grow up you will learn that a smaller machine has less metal to expand and contract and so you are not comparing apples to apples. Also newer Haas machines have become better than the earlier generations just like Deawoo grew out of the joke they were when they started out and evolved into a decent machine. As far as Titan he has other reasons besides accuracy to switch machines just like he switched locations from Ca. to Tx. Again when you are older you will not so quickly jump to easy conclusions and investigate what can not be easily seen. You might take a look at the Pierson ST-30Y update and hear about an experience with a recent Haas lathe from someone that has both brands in house.
@@3markaw I'm plenty grown up (46). I've been in the machining trade for about 20 years. I've worked on Haas machines, both mills and lathes of many different vintages. They have gotten better, I'll give you that, but they are still basic commodity machines.
I looked at the Pierson ST-30Y video. In the comment section he states to "never pay full price for a Hass". That is not what I would call a ringing endorsement. He also states in the video that he was impressed that it could do +/-.001 out of the box? Are you kidding me? Is that a joke? Plus he's only had the machine a year. Talk to him again in 5 or 10 and see how he feels about it. We have a 25 year old Okuma at my shop that still does .0005 tolerances on a regular basis.
What were Titan's reasons for ditching the Haas machines? If not for their flimsy build quality? What then? I've never seen a video where he addresses that issue. You seem to think you have that information, please enlighten me.
For someone who hated lathe and turning in general you presume to tell people how to turn precision parts.
You hated lathes SOOO BAD. It's almost comical to see you do a video centered around one.
If I had left a comment 10 years ago saying "John - you will one day be doing a video, of an ST20 (that you own, btw)" you would have responded with "HAHA. U kno NOTHING!"
Very informative, nice. However the post editing "style" of this video becomes annoying. What I mean is the editor of the upload removing frames in the video to give that stutter or frame jump effect... irritating to watch. Maybe it's thought of as an edgy "modern" effect for the audience but me personally I find it an irritation, it reminds me of the really old animation/video bits from Max Headroom (look it up).
I believe they cut out pauses and chose the better among many takes for particular words and phrases ("comping")
This is super common for audio, but looks bad in video. (Unless John can keep his head clamped in a vise while doing all the takes...)
Max Headroom 🤣🤣🤣
Unfortunately making videos for CZcams is not so easy.
At least happy for the content.
I have to give a big 👍👍👍 to John for sick at it for so long.
With all the criticism he has received over the years of making videos.
Takes A Lot to keep going.
This guy looks like he chases down lil punks on dirt bikes ..😂
Okay i wil never buy a haas lathe hahhahahaha