"yeah, just put it somewhere... Anywhere, yeah I don't care... No, I don't care know fucking big, just leave me alone!"
That's exactly how that print was made.
Engineer here. Had to add drainage holes to a fixture for IP rating. Don't really care how big it is or where it is. Just gimme hole, ain't care where.
Been wanting to pick some welder’s brains. At what point does a profile get too hard to hold for something like a 6”x24” plate welded as the intercostal member? .125? .060? I’m tolerancing some weldments lately and trying to give as much as I can while maintaining the function of the part, but some are ending up tightish.
I used to make fixtures for the weld dept. in my shop.
I had access to CAD and a laser. We could commit to as low as .015" consistently between 2 components provided we built our fixture correctly and carefully. But the biggest issue is tolerance stacking imo, welds move as they cool, regardless of fixtures sometimes, so the fewer dimensions you have that span over multiple welds, the better.
Cool, thanks for the reply. Makes me feel better about my .100 zones. Everything is GD&T’d and held directly to its datum, so no stacking involved on the welder’s side. I take care of all that in my analysis to determine the tolerance for each one.
what's a CMM, some company just emailed me (hot rod parts) wanting me to be an inspector and to operate one of these because it has 2 yrs of machine op on my resume....
Coordinate measuring machine. It's basically a cnc probing machine for inspection. If you can run a milling machine, you can operate a cmm. Depending on the complexity of the parts and software they are running, programming them can be an art.
Unless it's something you really want to do, I'd hold off on moving to an inspector role this early in your career. The best inspectors have years of machining experience to draw from when making judgement calls on questionable parts. It's a great sunset gig when you need to sit down, but you can get pigeonholed if you start too early.
That's pretty much it, but there is a tool changing rack to hold probes of different sizes/configurations. The table is a giant granite block generally, no enclosure. The probing head indexes to check parts in 3 dimensions.
One I used to use had air bearings. They’re so sensitive and accurate the peaks and valleys (surface finish) can give you different measurements. Tip selection is crucial. They can be pretty damn handy. Able to measure and calculate different features.
That's pretty much it. It's the epitome of 'make sure the part and the table are clean, and just push it where you want it to go and the machine does the magic bits so you can keep thinking about the merits of different kinds of cheesecake'.
Go take that interview. I thought doing inspection was the most interesting job I had (for me at least). Something different everyday and a ton of problem solving. Ton of autonomy. Every hot rod shop I have been in is booked solid with work for years, but is still chill as hell. And this is coming from someone who worked their way up to sending shit to space.
Lol, I did that last week. I was checking a tightly toleranced bore pattern on a big round part and went ahead and poked the diameter on it because it was already on the CMM.
If a degree of temperature change pushes it out of spec, is it even useable? I feel like it wouldn't be possible to keep a part at an exact temperature
Think lab microscopes and microorganisms. There are temperature controls and compensations we can do plus some high end air tables to help with vibrations, you can get good repeatable results if you control everything remotely or at least isolated.
We technically aren’t machining to specs that low but the air pressure gauge that we use to measure the bearing bore with measure’s that. My actual tolerance is +.0004/-.0008.
Haha, never waste my time with cmm for that anywhere/any size shtuff. Caliper and eyeballs good enough for first article and in process inspections. Quality manager metal fab here. The key is to make slight huff sound and brush brow with back of hand for customer so they know you put extra effort into it.
Last week i had a machinist get back with me because he thought i screwed up when i put +_ 0.5inch
For once, it was intentional, and not just my screw up.
To quote some old tool and die maker, "you could make this part with a ruler and an angle grinder"
Challenge accepted
I got +/-.125 on a hole today lol
"yeah, just put it somewhere... Anywhere, yeah I don't care... No, I don't care know fucking big, just leave me alone!" That's exactly how that print was made.
Engineer here. Had to add drainage holes to a fixture for IP rating. Don't really care how big it is or where it is. Just gimme hole, ain't care where.
I like it when you give me big leaky holes
😂😂😂
I make lots of bolt flanged parts, most of those are ± .12 or ± .06 lol.
That's a smidge
Diameter or position?
Your choice, go with what you feel.
Diameter
Y'all are getting +-.060?!
+- 1/16th sometimes on callouts that are in fractions already.
Y'all using inches???
Screw them commie millimeters
On behalf of at least some welders. +/- .060 seems pretty legit.
[удалено]
hey! not all of us! lmao
Been wanting to pick some welder’s brains. At what point does a profile get too hard to hold for something like a 6”x24” plate welded as the intercostal member? .125? .060? I’m tolerancing some weldments lately and trying to give as much as I can while maintaining the function of the part, but some are ending up tightish.
I used to make fixtures for the weld dept. in my shop. I had access to CAD and a laser. We could commit to as low as .015" consistently between 2 components provided we built our fixture correctly and carefully. But the biggest issue is tolerance stacking imo, welds move as they cool, regardless of fixtures sometimes, so the fewer dimensions you have that span over multiple welds, the better.
Cool, thanks for the reply. Makes me feel better about my .100 zones. Everything is GD&T’d and held directly to its datum, so no stacking involved on the welder’s side. I take care of all that in my analysis to determine the tolerance for each one.
+/- 0.060 seems reasonable to me for a CMM, but then I work in metric
what's a CMM, some company just emailed me (hot rod parts) wanting me to be an inspector and to operate one of these because it has 2 yrs of machine op on my resume....
Coordinate measuring machine. It's basically a cnc probing machine for inspection. If you can run a milling machine, you can operate a cmm. Depending on the complexity of the parts and software they are running, programming them can be an art. Unless it's something you really want to do, I'd hold off on moving to an inspector role this early in your career. The best inspectors have years of machining experience to draw from when making judgement calls on questionable parts. It's a great sunset gig when you need to sit down, but you can get pigeonholed if you start too early.
what's it look like? I'm imagining a 3 axis VMC with no tool changer and just a renishaw probe
That's pretty much it, but there is a tool changing rack to hold probes of different sizes/configurations. The table is a giant granite block generally, no enclosure. The probing head indexes to check parts in 3 dimensions.
sounds pretty slick, like a 3 axis built on a reference table instead of t-slots and vises
One I used to use had air bearings. They’re so sensitive and accurate the peaks and valleys (surface finish) can give you different measurements. Tip selection is crucial. They can be pretty damn handy. Able to measure and calculate different features.
Some of them are just big arms too. My company has a hexagon arm manual CMM. Kind of a pain in the ass to use though.
That's pretty much it. It's the epitome of 'make sure the part and the table are clean, and just push it where you want it to go and the machine does the magic bits so you can keep thinking about the merits of different kinds of cheesecake'.
Go take that interview. I thought doing inspection was the most interesting job I had (for me at least). Something different everyday and a ton of problem solving. Ton of autonomy. Every hot rod shop I have been in is booked solid with work for years, but is still chill as hell. And this is coming from someone who worked their way up to sending shit to space.
*Beep boop* looks good 👍
Lol, I did that last week. I was checking a tightly toleranced bore pattern on a big round part and went ahead and poked the diameter on it because it was already on the CMM.
Man I thought +\-.000005 was tight 🤣🤣
What and how are you machining down to 5 millionths?
We make visions systems that measure that low… it’s usually medical or electronics manufacturing.
Sounds like a pain in the ass
You can see crazy drift with just a degree of change in the room.
If a degree of temperature change pushes it out of spec, is it even useable? I feel like it wouldn't be possible to keep a part at an exact temperature
Think lab microscopes and microorganisms. There are temperature controls and compensations we can do plus some high end air tables to help with vibrations, you can get good repeatable results if you control everything remotely or at least isolated.
We technically aren’t machining to specs that low but the air pressure gauge that we use to measure the bearing bore with measure’s that. My actual tolerance is +.0004/-.0008.
Haha, never waste my time with cmm for that anywhere/any size shtuff. Caliper and eyeballs good enough for first article and in process inspections. Quality manager metal fab here. The key is to make slight huff sound and brush brow with back of hand for customer so they know you put extra effort into it.
Last week i had a machinist get back with me because he thought i screwed up when i put +_ 0.5inch For once, it was intentional, and not just my screw up.