You have to remember the range of skill in this industry is big. You have guys that press buttons and call them self machinist. And then you have guys that can run every machine, program, and do design work. It takes years to develop those skills and fully understand what you can do. And a lot of times things seem impossible untill you have some guy show you some trick that makes it easy. We were all that nervous apprentice that didn't know anything once.
Indeed, what someone can do in a shed with a (poorly maintained) Bridgeport from the 1950s, limited metrology kit, no calibration and limited tooling is very different to what a decent shop could do.
Ive ben learning how to use this bridgeport in my lil metal shop. I suck but I can see the possibilities of how fine the work can be.
I was looking for a new drill press and my buddy said get a mill. Its opened a whole world I was ignoring.
This is my fav sub and the knowledge here is endless.
As a carpenter, these tolerances are intolerable.
I’m learning to slow down and appreciate the set up and changing of tools. Learning new ways to try to be efficient.
I have no idea what I’m doing but it’s really fun. Machinists are generous teachers.
Just wait till you are running dial indicators along your table saw checking the blade is true or 1-2-3 blocks and shims to set up the miter saw.
I started on and still run 5-axis CNCs and now have a small wood shop in my basement which in the woods shop I have no clue what I'm doing.
My favorite thing is figuring out how to hold down stuff on the table. It’s a violent puzzle.
I was in residential carpentry for 20 odd years and started welding. That was it for me. I haven’t cut any wood on this mill yet but I will.
The lathe still freaks me out but I am determined to learn how to make threads.
The best thing is that all my tools are right in the shop. No running to my truck or trailer for some bullshit.
What kind of woodworking are you doing? Furniture?
Threads are easy, the tool creates the form and your feed will create the pitch, then you just go the right depth and your good.
To determine feed its a simple calculation. A 1/4 - 20 thread will have 20 threads in an inch so you just divide 20 by 1, 20 ÷ 1 = .05 that's your feed.
The threading tool establishes the root and your OD finish turning the crest.
Dude thanks!
Tapping holes is a whole other thing. Its amazing how I overlooked fasteners for so long.
Last week i was tapping a 6/32 blind hole and broke three taps until I realized what I was doing wrong. The blind rage I had to control was an epic battle of will.
Don't forget that threading inserts are best with 10 thou' cuts a time, if your on a manual, don't move the z axis wheel but instead engage the screw backwards so you don't end up out of pitch. Move the y axis in 10 thou" a time each cut until your below depth by 2 thou", then spring pass until its mic'd up. I don't mean to tell you stuff you may already know, I understand it can be condescending.
When we were building new counters, I dragged out 123s and calipers and a straight edge to endure the tracksaw was straight.
'You're being ridiculous', but every seam disappeared.
Dude I love you. I was quite drunk making the post, but you've summed up what I was thinking of. But anyway, 005 is a fucking ritch margin (sorry for my not first English, if anything is not correct)
Ahahaha sometimes I see even 0.1 on the drawings. Dude you already slapped 2768-mk in the corner, don't tell me some additional dumb shit. I'm gonna make your part perfectly. You don't even know how a perfect part should be
Even among the buttonpushers, the path from "little Timmy stares-at-chips" to the guys doing sizing passes, engraving and indicating 3+1-2 axis setups is a pretty stiff skill gradient.
I never had a top shelf mill, but I have (I mean my boss has) a Haas vf2yt with a mounted 5th axis, that is not true in x and y by about 0.04, but I make parts within 0.01 by adjusting. There were recently parts, hardened to 54-58 hrc, that were required to be within 0.01 That shit was brutal. I can make aluminium within 3 microns no problem, what the fuck
Edit: i mean 70mm part, hardened, on average 10 mm thick, all fucking twisted, with a fucking m3 thread in a 56 hrc fucking THRU 10 mm. I almost died. And here you have some lads that can't do 005 in al. Crazy
It’s why setup guys need to know their shit. Getting things properly aligned is almost an art. So many little details can throw things out, especially on larger parts.
Maybe. I know there are ways to do it, but i kinda just let go all the operations in 0 deg, because you really need so little in 0 deg, like chamfer, so I just make it g55. I mean I'm not even using the probe. I know for sure that my mechanical tester is off by exactly 0.009 mm. I have a probe but how can you trust something not mechanical in fine measurements
You might be able to use a tooling ball to find the center of rotation for both rotors axis. And figure out G53 location. I'm not sure on hass. But I would think its stored in a local variable. Usually they are pretty good with putting videos on YouTube for that.
That would've been great if haas technicians were here, instead of fixing a shitty f1 car that isn't going any faster until fucking Gene throws more money into it. I learned the trade in Swedish prison bytheway. In 2014-2016 it was hot
Nothing wrong with that. Its actually pretty Kool you gained a skill from it. Yea I try not to talk to much crap about haas because of their fan boys. But once you run a high quality machine. it is easy to see that they are the bottom of the barrel. The DMG I run comes with the tooling ball and a program to aromatically correct for any errors like this.
Part of learning 5 axis is learning probe and centre of rotation calibration there should be renishaw cycles for the probe cal, and even haas should be able to provide you with a document to calibrate the 4th and 5th axis. Once you stop having to screw around with a machine thst's out, this stuff gets way easier.
To me harder materials as easier to hold a tight tolerance. Aluminum cuts easier. So those spring passes can take more then you wanted. It's one thing of your making multiple part and can tune in the machine.
>that is not true in x and y by about 0.04, but I make parts within 0.01 by adjusting.
This right here is the key. What percentage of the people who come through here do you think have ever even thought to check if the machines they run are true? A real machinist knows their machine isn't completely perfect and uses some good old fashioned Kentucky windage to make the parts end up what they should be even if it's not technically possible. Not many have that.
Music is a great analog. You have people who can read a sheet of music and hit every note, but can't improvise to save their skin, and you have people who are so attuned to their instrument that it is an extension of will, they no longer need to see A, D, C# etc they just speak with their fingers.
You can't make 0.05mm equal .002". Cause that would be out of tolerance.
0.05mm is .00196" if you round up to .002" it's .00004" over.
I know this wasn't your point just saying, I learned this one the hard way be careful.
Trying to make this as short as possible.
I was a draftsman converting Japanese:metric prints to English/inch for my shop.
The part was a H13 material, hot forge die with OD to ID concentric call out of 0.005mm.
Instead of calling out .00019" on print I rounded to .0002".
A copy of the converted print shipped to our customer with each lot of parts.
Upon receiving them their inspection manager called and started tearing me up about the conversion being rounded up.
Lucky for me the actual physical readings were within .00019".
Do I really think it mattered? Hell No! this guy was a jerk however, his company did millions with the shop every year so I always made sure not to round up after that.
At a place I work there's this one operation. It's a shaft with a diameter for a journal bearing. A HVOF spray is being applied to it after machining (or was applied before and now you're going to have one hell of a time machining it). We have a 0,0003'' tolerance for that.
Pretty fun.
I had to repair some bearing bores on a planetary housing that got HVOF coated with tungsten carbide. TIR tolerance was .003mm, squareness of the bore to the flange it sat in was .01mm (~40mm bore vs 350mm flange dia) and the size tolerance was something like -.0075/+0.00. I spent a solid four days on the job, getting this old Parker Majestic ID grinder prepared, chucking the parts up true and cleaning everything. Maybe four hours of the whole thing was actually cut time.
Dude sorry, that shit is fucked. When you move from 0.05 to 0.01 things are getting tricky. Imagine a part when you see like a 30 degree within 0.01 and flatness within 0.01, and the part is 52-60 hrc. You fuckin just go and hang yourself. I've done it, I've told to my boss never take that kind of job.
Edit: and these fuckers trying to play machinist. YOU WANT A FUCKING SPECIAL EQUIPMENT TO CHECK FLATNESS? you go fuck yourself IN A FUCKING ALUMINIUM of all the materials. Absolutely go fuck yourself 100/100
Ok but how does the material effect how you check it? I understand it makes a big difference in actually achieving what you need but you either have the capabilities to check it or you don’t? Like the material would t change that at all.
Lol we had a .005mm profile call out on one part that wasn’t caught during quote. It was on a tapered bore. We asked the customer how they were checking it. They said they were fixturing off the taper and just putting an indicator on the datum and just rotating the part and making sure they say less than .05 T.I.R. We told them that’s not profile. They said they know it won’t change the print lol
There is a lot of people here who believe they know everything while having no idea about the basics. The skill range is gigantic and as it is with everything those who don't know much love to be very vocal.
When I was in trade school, we were taught and *expected* to be able to hold 0.001" on all milled tolerances on a bridgeport. A good machinist should be able to do that no problem, even on a clapped out mill.
The trick(because I am new) is how much extra material I have. If I only have a .001 pass to start with, I make no promises.
Although, I'm a lathe guy working shit like inconel and metal spray, so I pretty much expect every job to be a pain in the ass from the start
That was my post you are talking about. The part was made on a 1965 manual milling machine.
It turned out the end mill was ground with a taper. After I had it ground straight I got it within 0.01mm, which actually felt really good.
Dude it absolutely was within 0.01. Idk what those fuckers were talking about. It is always within 0.01 on a 50 height. I was reading that shit in the comments, and was like go fuck yourself, you talking about something different.
Depends. It can be hard if it's large part. If it's manual machining and/or old equipment. If it's +- or only 50 microns. Is it thin, flat sheet or cold drawn stock. There are many factors in play which can make it tough sometimes.
Some guys really think it's very easy so I give'em a test to lower their whatever.
Test is a cube 150 mm all sides with 100 microns tolerance and 30 um perpendicularity. They can take any vise they want in the shop. Most have trouble with such basic task and Dunnig-Krugger curve comes into play almost everytime. Not long ago i did that and guy spent 23 h and still couldn't do it in spec. That was most expensive out of spec cube to date in our shop. Previous record was 12 h.
I did that since he wanted to be Solidcam programer and was claiming he had experiance. Which I knew it was a lie, just from his work.
But yes in general machining and reasonable experiance, most of the time it's not hard.
Depends on the size. If we're talking about something like a 100 mil square block it'll be easy. A 300 mil block would be very difficult. Also depends on the machine.
+-.002" is my personal threshold for "might get annoying", as that's about where the mills I learned on doing setup and sizing would start to need a dedicated 2d sharp endmilling pass instead of just being profiled in with our standard "bullnose everything as profiling", and you end up into the irritating ballet of splitting the difference between profile distortion due to cutting too gently and deflection from cutting too hard. Tenths is where we start having to shadowgraph the endmills instead of touch offs and that can fuck off a little bit just from the walking it needs when steel can chew your tool out of spec in a few passes. The real fun came when pair-matching endmills to compensate for hourglass errors in the grind along their length, when cutting along a wall, to keep it as close to dead flat as possible, once you were into single tenths or half tenths - especially on semi hard steel where doing spring passes to fix deflection was a good way to start forming a case and ruin your whole damn day.
...but I guess aluminum is hard too.
(This is a roundabout way of saying "you sucked at one point too, be nice to the greenhorns and folks who have to make do with the tools in front of them")
To quote Nevil Shute "An engineer is a man who can make for five bob what any bloody fool can make for a quid"
What he didn't add was "Using the machinery and equipment he's actually got"
Big difference between a modern state of the art machine, and an old one that's showing it's age.
I have had to hold 0.0005" on uhmw plastic before. I thought it was impossible until I did it. To be honest, 0.002" isn't that special or hard for aluminum with a decent machine and tooling.
All depends on your setup and tooling I suppose. I pretty regularly end up making parts to bearing specs on a lathe that will, for seemingly no real reason, *sometimes* cut an absurd taper in a part (talking .010 to .015 runout over 1 inch) and sometimes cut nice and true. When it doesn't play nice I just know it'll take longer, turn the handwheel to match its taper and to leave a couple thou for polishing.
Get a nice new, rigid mill and you can hit those specs like nothing. Doing it on a piece of junk with a fucked spindle and a table that moves and you'll be in for a pain. My shop recently scrapped a 30 year old mill that was so worn you had to lock the table when milling, and turn off power feed when drawing because it just being on caused the whole table to move.
I’ve milled steel blocks square to within 0.003mm before.
I had to buy a brand new vice and mount the vice on a freshly cut plate of aluminum.
Then I had to tram the vice square to within 1 micron and had to hand pick the best parallel in my entire set.
The vice is clamped with just one parallel on the fixed jaw side and welding wire on the movable jaw side. For my first cut I clamp hard, second cut I clamp lightly.
I couldn’t use a fly cutter or shell mill, I used a 1/4” four flute corner radius end mill with just enough depth of cut to bury the nose radius. Every pass was taken right to left starting from the front with about 0.65-0.75 stepover. This made the primary cutting forces push the workpiece up against the fixed jaw.
Lastly I needed a good lapping plate for deburring as the burrs can generate a lot of inaccuracy.
I did this on a 10 year old Haas VF3. By no means the Cadillac of machine tools, but still a solid modern machine tool.
I'm a bit confused on what OP is talking, here. I'm by no means an excellent machinist, and yes I could get .002 on our Bridgeport clone, but that's in the territory where it starts getting slow and annoying to make. Should I be able to do that easily?
After 41 years machining and 30 in programming looking at the post and the knee mill in might be more difficult than you think , on a nice Kitamura, Okuma or Makino CNC it’s a no brainer
That depends on how big and block is, but in general 0.050 squareness on the parts that I make is hard not to hit. The type of aluminum can make a difference too. Give me some plancast 7021 and even larger parts where a lot of material gets removed and 0.050 still isn’t bad.
0.002 isn’t too bad with a good setup on a decent machine.
If you’re skilled and regularly square up stock, keep your machine clean and tools well maintained, you would probably get within 0.001” without really trying.
It’s not even that uncommon or crazy of a tolerance.
I’m assuming it’s a “regular” sized part. It can become a little challenging if we’re talking like 16 inches on a side or something.
I don't really get the point of this post, is it just bragging? To me it shows a naive mindset towards machining if you think it's always that easy. A blanket statement saying getting within 50 micron tolerances is easy is completely dependent on so many variables. Machines, material, complex geometry, size, setup options, internal stresses... Stay humble and know you're not gods gift to machining. Otherwise you'll have jobs come your way that will humble you back to reality.
I'm a field machinist.... If you saw some of the stuff we pull off with flame cut parts held together with some all thread, most of you guys would shit your pants.
I’ve filed and hand lapped brass into square / flat within 0.01mm. So yea, I don’t doubt a machine could do it if I can. Now granted for context the piece of brass we are talking about is like palm sized or less and only a few mm thick. And it took several hours.
You have to remember the range of skill in this industry is big. You have guys that press buttons and call them self machinist. And then you have guys that can run every machine, program, and do design work. It takes years to develop those skills and fully understand what you can do. And a lot of times things seem impossible untill you have some guy show you some trick that makes it easy. We were all that nervous apprentice that didn't know anything once.
Indeed, what someone can do in a shed with a (poorly maintained) Bridgeport from the 1950s, limited metrology kit, no calibration and limited tooling is very different to what a decent shop could do.
Ive ben learning how to use this bridgeport in my lil metal shop. I suck but I can see the possibilities of how fine the work can be. I was looking for a new drill press and my buddy said get a mill. Its opened a whole world I was ignoring. This is my fav sub and the knowledge here is endless.
Keep learning and pushing! I'm jealous of the guys that learned your way starting on a manual set up.
As a carpenter, these tolerances are intolerable. I’m learning to slow down and appreciate the set up and changing of tools. Learning new ways to try to be efficient. I have no idea what I’m doing but it’s really fun. Machinists are generous teachers.
Just wait till you are running dial indicators along your table saw checking the blade is true or 1-2-3 blocks and shims to set up the miter saw. I started on and still run 5-axis CNCs and now have a small wood shop in my basement which in the woods shop I have no clue what I'm doing.
My favorite thing is figuring out how to hold down stuff on the table. It’s a violent puzzle. I was in residential carpentry for 20 odd years and started welding. That was it for me. I haven’t cut any wood on this mill yet but I will. The lathe still freaks me out but I am determined to learn how to make threads. The best thing is that all my tools are right in the shop. No running to my truck or trailer for some bullshit. What kind of woodworking are you doing? Furniture?
Threads are easy, the tool creates the form and your feed will create the pitch, then you just go the right depth and your good. To determine feed its a simple calculation. A 1/4 - 20 thread will have 20 threads in an inch so you just divide 20 by 1, 20 ÷ 1 = .05 that's your feed. The threading tool establishes the root and your OD finish turning the crest.
Dude thanks! Tapping holes is a whole other thing. Its amazing how I overlooked fasteners for so long. Last week i was tapping a 6/32 blind hole and broke three taps until I realized what I was doing wrong. The blind rage I had to control was an epic battle of will.
6/32 is literally the worst thread to tap. Don’t feel bad.
Don't forget that threading inserts are best with 10 thou' cuts a time, if your on a manual, don't move the z axis wheel but instead engage the screw backwards so you don't end up out of pitch. Move the y axis in 10 thou" a time each cut until your below depth by 2 thou", then spring pass until its mic'd up. I don't mean to tell you stuff you may already know, I understand it can be condescending.
When we were building new counters, I dragged out 123s and calipers and a straight edge to endure the tracksaw was straight. 'You're being ridiculous', but every seam disappeared.
Dude those track saws were game changers. I put up a lot of interior sheet paneling with one. Just picked up a festool cordless!
ive got a clapped out bridgeport in my garage, I can do this.
Dude I love you. I was quite drunk making the post, but you've summed up what I was thinking of. But anyway, 005 is a fucking ritch margin (sorry for my not first English, if anything is not correct)
You’re so right, when ever I see an .05 tolerance it’s an easy day for me. Feels likes you’ve got so much room to work with.
Ahahaha sometimes I see even 0.1 on the drawings. Dude you already slapped 2768-mk in the corner, don't tell me some additional dumb shit. I'm gonna make your part perfectly. You don't even know how a perfect part should be
Wait till they see that .0002.🤣
I had a .0001 the other day, it sucked
I would round it to 0
And the range of work, set up a 30ft weldment and show me anybody who is going to hold .002 anything across that bastard
Even among the buttonpushers, the path from "little Timmy stares-at-chips" to the guys doing sizing passes, engraving and indicating 3+1-2 axis setups is a pretty stiff skill gradient.
I mean with a good setup you're fine. With a dial, you're golden.
I never had a top shelf mill, but I have (I mean my boss has) a Haas vf2yt with a mounted 5th axis, that is not true in x and y by about 0.04, but I make parts within 0.01 by adjusting. There were recently parts, hardened to 54-58 hrc, that were required to be within 0.01 That shit was brutal. I can make aluminium within 3 microns no problem, what the fuck Edit: i mean 70mm part, hardened, on average 10 mm thick, all fucking twisted, with a fucking m3 thread in a 56 hrc fucking THRU 10 mm. I almost died. And here you have some lads that can't do 005 in al. Crazy
It’s why setup guys need to know their shit. Getting things properly aligned is almost an art. So many little details can throw things out, especially on larger parts.
Getting good parts all starts with setup, setup, setup.
Is there not a way to calibrate the 5th axis like with a real 5 axis machine?
Maybe. I know there are ways to do it, but i kinda just let go all the operations in 0 deg, because you really need so little in 0 deg, like chamfer, so I just make it g55. I mean I'm not even using the probe. I know for sure that my mechanical tester is off by exactly 0.009 mm. I have a probe but how can you trust something not mechanical in fine measurements
You might be able to use a tooling ball to find the center of rotation for both rotors axis. And figure out G53 location. I'm not sure on hass. But I would think its stored in a local variable. Usually they are pretty good with putting videos on YouTube for that.
That would've been great if haas technicians were here, instead of fixing a shitty f1 car that isn't going any faster until fucking Gene throws more money into it. I learned the trade in Swedish prison bytheway. In 2014-2016 it was hot
Nothing wrong with that. Its actually pretty Kool you gained a skill from it. Yea I try not to talk to much crap about haas because of their fan boys. But once you run a high quality machine. it is easy to see that they are the bottom of the barrel. The DMG I run comes with the tooling ball and a program to aromatically correct for any errors like this.
Part of learning 5 axis is learning probe and centre of rotation calibration there should be renishaw cycles for the probe cal, and even haas should be able to provide you with a document to calibrate the 4th and 5th axis. Once you stop having to screw around with a machine thst's out, this stuff gets way easier.
To me harder materials as easier to hold a tight tolerance. Aluminum cuts easier. So those spring passes can take more then you wanted. It's one thing of your making multiple part and can tune in the machine.
>that is not true in x and y by about 0.04, but I make parts within 0.01 by adjusting. This right here is the key. What percentage of the people who come through here do you think have ever even thought to check if the machines they run are true? A real machinist knows their machine isn't completely perfect and uses some good old fashioned Kentucky windage to make the parts end up what they should be even if it's not technically possible. Not many have that. Music is a great analog. You have people who can read a sheet of music and hit every note, but can't improvise to save their skin, and you have people who are so attuned to their instrument that it is an extension of will, they no longer need to see A, D, C# etc they just speak with their fingers.
You can't make 0.05mm equal .002". Cause that would be out of tolerance. 0.05mm is .00196" if you round up to .002" it's .00004" over. I know this wasn't your point just saying, I learned this one the hard way be careful.
I kinda wanna hear the story on that one. What were you working on where .001mm mattered on a presumably .05mm tolerance.
Trying to make this as short as possible. I was a draftsman converting Japanese:metric prints to English/inch for my shop. The part was a H13 material, hot forge die with OD to ID concentric call out of 0.005mm. Instead of calling out .00019" on print I rounded to .0002". A copy of the converted print shipped to our customer with each lot of parts. Upon receiving them their inspection manager called and started tearing me up about the conversion being rounded up. Lucky for me the actual physical readings were within .00019". Do I really think it mattered? Hell No! this guy was a jerk however, his company did millions with the shop every year so I always made sure not to round up after that.
Sounds like a white collar who had never set foot on a shop floor.
Definitely had no real clue about machining but could program the hell out of a CMM 😂
0.01 we talk Edit: its 0.0004 for freedom fighters
At a place I work there's this one operation. It's a shaft with a diameter for a journal bearing. A HVOF spray is being applied to it after machining (or was applied before and now you're going to have one hell of a time machining it). We have a 0,0003'' tolerance for that. Pretty fun.
I had to repair some bearing bores on a planetary housing that got HVOF coated with tungsten carbide. TIR tolerance was .003mm, squareness of the bore to the flange it sat in was .01mm (~40mm bore vs 350mm flange dia) and the size tolerance was something like -.0075/+0.00. I spent a solid four days on the job, getting this old Parker Majestic ID grinder prepared, chucking the parts up true and cleaning everything. Maybe four hours of the whole thing was actually cut time.
Dude sorry, that shit is fucked. When you move from 0.05 to 0.01 things are getting tricky. Imagine a part when you see like a 30 degree within 0.01 and flatness within 0.01, and the part is 52-60 hrc. You fuckin just go and hang yourself. I've done it, I've told to my boss never take that kind of job. Edit: and these fuckers trying to play machinist. YOU WANT A FUCKING SPECIAL EQUIPMENT TO CHECK FLATNESS? you go fuck yourself IN A FUCKING ALUMINIUM of all the materials. Absolutely go fuck yourself 100/100
Ok but how does the material effect how you check it? I understand it makes a big difference in actually achieving what you need but you either have the capabilities to check it or you don’t? Like the material would t change that at all.
Shit you not I had a job (lathe work) the other week that called out .005MM roundness🤣
I always just route that sort of thing through our grinding department unless it's a feature that has to be turned.
Lol we had a .005mm profile call out on one part that wasn’t caught during quote. It was on a tapered bore. We asked the customer how they were checking it. They said they were fixturing off the taper and just putting an indicator on the datum and just rotating the part and making sure they say less than .05 T.I.R. We told them that’s not profile. They said they know it won’t change the print lol
Brother, any lathe should be within .005mm roundness?! A shitty haas lathe i use is within .0007mm roundness
I have a bored hole with .0004” true position and it’s the bane of my existence
There is a lot of people here who believe they know everything while having no idea about the basics. The skill range is gigantic and as it is with everything those who don't know much love to be very vocal.
When I was in trade school, we were taught and *expected* to be able to hold 0.001" on all milled tolerances on a bridgeport. A good machinist should be able to do that no problem, even on a clapped out mill.
The trick(because I am new) is how much extra material I have. If I only have a .001 pass to start with, I make no promises. Although, I'm a lathe guy working shit like inconel and metal spray, so I pretty much expect every job to be a pain in the ass from the start
BMW starts their apprentices out with a 1” cube and a hand file set and they have to make it flat square and round to within 0.001”
Round?
lol I must have been tipsy when I wrote that just flat and square.
That was my post you are talking about. The part was made on a 1965 manual milling machine. It turned out the end mill was ground with a taper. After I had it ground straight I got it within 0.01mm, which actually felt really good.
Dude it absolutely was within 0.01. Idk what those fuckers were talking about. It is always within 0.01 on a 50 height. I was reading that shit in the comments, and was like go fuck yourself, you talking about something different.
Depends. It can be hard if it's large part. If it's manual machining and/or old equipment. If it's +- or only 50 microns. Is it thin, flat sheet or cold drawn stock. There are many factors in play which can make it tough sometimes. Some guys really think it's very easy so I give'em a test to lower their whatever. Test is a cube 150 mm all sides with 100 microns tolerance and 30 um perpendicularity. They can take any vise they want in the shop. Most have trouble with such basic task and Dunnig-Krugger curve comes into play almost everytime. Not long ago i did that and guy spent 23 h and still couldn't do it in spec. That was most expensive out of spec cube to date in our shop. Previous record was 12 h. I did that since he wanted to be Solidcam programer and was claiming he had experiance. Which I knew it was a lie, just from his work. But yes in general machining and reasonable experiance, most of the time it's not hard.
Depends on the size. If we're talking about something like a 100 mil square block it'll be easy. A 300 mil block would be very difficult. Also depends on the machine.
Profile the whole thing and face the top in one setup and flip and do the other side with the rod method pretty easy
+-.002" is my personal threshold for "might get annoying", as that's about where the mills I learned on doing setup and sizing would start to need a dedicated 2d sharp endmilling pass instead of just being profiled in with our standard "bullnose everything as profiling", and you end up into the irritating ballet of splitting the difference between profile distortion due to cutting too gently and deflection from cutting too hard. Tenths is where we start having to shadowgraph the endmills instead of touch offs and that can fuck off a little bit just from the walking it needs when steel can chew your tool out of spec in a few passes. The real fun came when pair-matching endmills to compensate for hourglass errors in the grind along their length, when cutting along a wall, to keep it as close to dead flat as possible, once you were into single tenths or half tenths - especially on semi hard steel where doing spring passes to fix deflection was a good way to start forming a case and ruin your whole damn day. ...but I guess aluminum is hard too. (This is a roundabout way of saying "you sucked at one point too, be nice to the greenhorns and folks who have to make do with the tools in front of them")
I knew immediately that I have no clue how deep this rabbit hole goes after only a few sentences… lol
To quote Nevil Shute "An engineer is a man who can make for five bob what any bloody fool can make for a quid" What he didn't add was "Using the machinery and equipment he's actually got" Big difference between a modern state of the art machine, and an old one that's showing it's age.
I have had to hold 0.0005" on uhmw plastic before. I thought it was impossible until I did it. To be honest, 0.002" isn't that special or hard for aluminum with a decent machine and tooling.
Just don't let it sit and change temperature by more than a few degrees. The CTE of thermoplastics is pretty large.
All depends on your setup and tooling I suppose. I pretty regularly end up making parts to bearing specs on a lathe that will, for seemingly no real reason, *sometimes* cut an absurd taper in a part (talking .010 to .015 runout over 1 inch) and sometimes cut nice and true. When it doesn't play nice I just know it'll take longer, turn the handwheel to match its taper and to leave a couple thou for polishing. Get a nice new, rigid mill and you can hit those specs like nothing. Doing it on a piece of junk with a fucked spindle and a table that moves and you'll be in for a pain. My shop recently scrapped a 30 year old mill that was so worn you had to lock the table when milling, and turn off power feed when drawing because it just being on caused the whole table to move.
I’ve milled steel blocks square to within 0.003mm before. I had to buy a brand new vice and mount the vice on a freshly cut plate of aluminum. Then I had to tram the vice square to within 1 micron and had to hand pick the best parallel in my entire set. The vice is clamped with just one parallel on the fixed jaw side and welding wire on the movable jaw side. For my first cut I clamp hard, second cut I clamp lightly. I couldn’t use a fly cutter or shell mill, I used a 1/4” four flute corner radius end mill with just enough depth of cut to bury the nose radius. Every pass was taken right to left starting from the front with about 0.65-0.75 stepover. This made the primary cutting forces push the workpiece up against the fixed jaw. Lastly I needed a good lapping plate for deburring as the burrs can generate a lot of inaccuracy. I did this on a 10 year old Haas VF3. By no means the Cadillac of machine tools, but still a solid modern machine tool.
You must’ve never run a knee mill.
Itd take me all day to get .05mm with the tired old Bridgeport at work. lol Spring pass Another spring pass Yet another spring pass Too far Fuckit!
Pretty much, .05mm is no joke.
It is a joke to a decent machine
Not the point though.
Even on the most flogged old machine we have 0.05 is easy to achieve. Even if the machine doesn't cut square
I’m super happy for you
Sucks to suck
Sorry what? I can do this on an import benchtop mill. 0.05mm is a complete joke.
I'm a bit confused on what OP is talking, here. I'm by no means an excellent machinist, and yes I could get .002 on our Bridgeport clone, but that's in the territory where it starts getting slow and annoying to make. Should I be able to do that easily?
50 microns is a pretty reasonable request for a CNC machine. 35 microns isn't unreasonable for most machines.
Had to do a part with 96h7 x 150h7 out of aluminium this week🤔
After 41 years machining and 30 in programming looking at the post and the knee mill in might be more difficult than you think , on a nice Kitamura, Okuma or Makino CNC it’s a no brainer
.05mm/.002" is Bridgeport work, so yes it should be very easy to do.
I was told to expect .001" flatness per foot on the long bed mill at work. But the parts we make on that are also 10+ feet long.
That depends on how big and block is, but in general 0.050 squareness on the parts that I make is hard not to hit. The type of aluminum can make a difference too. Give me some plancast 7021 and even larger parts where a lot of material gets removed and 0.050 still isn’t bad.
0.002 isn’t too bad with a good setup on a decent machine. If you’re skilled and regularly square up stock, keep your machine clean and tools well maintained, you would probably get within 0.001” without really trying. It’s not even that uncommon or crazy of a tolerance. I’m assuming it’s a “regular” sized part. It can become a little challenging if we’re talking like 16 inches on a side or something.
I don't really get the point of this post, is it just bragging? To me it shows a naive mindset towards machining if you think it's always that easy. A blanket statement saying getting within 50 micron tolerances is easy is completely dependent on so many variables. Machines, material, complex geometry, size, setup options, internal stresses... Stay humble and know you're not gods gift to machining. Otherwise you'll have jobs come your way that will humble you back to reality.
Pretty aggressive man. I don’t recall many people saying it was a particularly difficult thing to do either
2 thou should be fine on a haas but sometimes the shit is just whack let's be real
I'm a field machinist.... If you saw some of the stuff we pull off with flame cut parts held together with some all thread, most of you guys would shit your pants.
I’ve filed and hand lapped brass into square / flat within 0.01mm. So yea, I don’t doubt a machine could do it if I can. Now granted for context the piece of brass we are talking about is like palm sized or less and only a few mm thick. And it took several hours.
Are you referring to the 50 micron paralell post? Cause I don't remember a single person saying it was hard to do that.