c/cnc-operators

Talked to a retired machinist and now I doubt my tool offsets

Guy next to me at a swap meet in Dayton said my gauge block routine was junk. He showed me his hand ground pins and said tolerances drift every 8 hours. Has anyone else done a mid-shift offset check and been off by 2 thou?

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gray314•1d ago

The insert that lasted 3x longer after I checked the wiper angle

Ran a job last month with a 45 degree lead angle on some 4140 and the inserts were burning out every 90 parts. I was about to blame the material or the coolant mix, then I grabbed the insert catalog from the drawer and actually read the chipformer specs. Turns out the wiper geometry was mismatched for my feed rate, I ran 0.012 per tooth but the insert wanted between 0.006 and 0.008. Swapped to a different insert with a tighter wiper radius and got 280 parts before I had to flip it. New inserts are a bit pricier but the cost per part dropped by 40%. Anyone else ever ignore the recommended feed range and pay for it in tool life?

2 comments

sanchez.julia•1d ago

Hit 10,000 parts on the same fixture today, never expected that number

I've been running this one job for a big automotive customer since March, and today the counter rolled over 10,000 parts on a single aluminum fixture. The tolerance is only 0.005 inches on the bore, so I check every 50th piece with the CMM, and it's still holding better than when we set it up. Honestly surprised the soft jaws lasted this long, I've replaced them maybe twice but the base plate is original. What's the longest run you guys have had on one setup before re-tooling?

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taylor.brooke•2d ago

Swarf management: coolant flood vs mist, which one is actually better for visibility?

Started running a new job last week on our Haas VF-2, 6061 aluminum, deep pocket work. We had it set up with flood coolant and I couldn't see a thing through the fog, kept stopping to wipe the window and check the tool. Switched to a mist setup for the second part and the difference in visibility was night and day. But now I'm worried about heat buildup in the tool and the part. I know the flood is better for cooling but the mist keeps the cut zone clear and I can actually watch for chip recutting. What are you guys running for aluminum pocket work? Is the tradeoff worth it or am I just making problems for tool life? Has anyone else dealt with this same wall of fog thing?

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victorhernandez•5d ago

That Fadal spindle load meter told me more than I expected this morning

I was running a batch of 304 stainless parts this morning and kept seeing the load meter sit at 72% on the finish pass. Same program I've run 50 times, same tooling, same fixturing, but normally it hovers around 55%. Took me a minute to realize the coolant concentration was off because the mix pump had been acting up since the last filter change. I dumped the sump and re-mixed it, and sure enough the load dropped right back down. Makes me wonder how many times I've blamed the insert or the feed rate when the real issue was fluid condition. Do you guys check your coolant concentration before messing with speeds and feeds, or is that just me?

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quinnperry•6d ago

Old timer at my shop told me to ignore tool wear compensation, nearly scrapped a $400 part

Honestly, this guy named Tom has been running CNCs since the 80s, so I figured he knew his stuff. He said I didn't need to adjust the wear offset for a finish pass on a titanium job we do for a medical place in Austin. I listened to him, ran the part, and it came out .003 over tolerance on 6 critical bores. Had to redo the whole setup and lost half a shift. Has anyone else had a senior guy give advice that just doesn't hold up anymore?

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jason_knight•7d ago

Hit 10,000 hours on my old Haas last Tuesday and it kinda threw me off

I was just checking the machine log after a run of about 50 parts for a local shop in Denver that does medical stuff. The counter rolled over to 10,000 hours on the spindle and I had to stop and think for a second. That machine came to our floor back in 2012, I was still learning G-code from a beat up manual. It's got dents and coolant stains all over the door, I replaced the way wipers twice and the tool changer acts up every winter when it gets cold. But it just keeps going, you know? I honestly didn't expect to be running the same machine for that long. Has anyone else here had a machine hit some crazy hour count that surprised you?

3 comments

iris_barnes87•7d ago

Switched to diamond tooling on aluminum and ate through stock way too fast

I've been running 6061 on a Haas VF-2 for about 3 years now and always used carbide end mills with good results. Last month I tried a $120 Kennametal diamond coated end mill because I heard it would outlast carbide and give a better finish. Turns out it chipped on the second part and left a terrible surface finish on the rest of the job. Has anyone else had a bad experience running diamond tooling on non-abrasive materials or is it just my feeds and speeds being off?

2 comments

joseph_green13•7d ago

Debate: Was my $400 custom fixturing setup a waste or a win?

I spent about $400 on a custom fixture for a repeat aluminum part job about 3 months ago. The idea was to save time on setup and hold tighter tolerances, but so far I've only run that job twice. The fixture works great and cut cycle times by 15%, but I'm wondering if the money could've gone to better tooling or a new vise. Has anyone else here gambled on a custom solution that didn't pay off fast enough?

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park.aaron•9d ago

Spent $80 on a used set of carbide end mills and it was a total gamble

Picked up a lot of 10 from a guy on Facebook Marketplace, figured even if half were dull I'd break even. Turns out 8 out of 10 cut like butter on some 4140 I had to run last Friday. Anyone else ever score decent tooling from random sellers or just me?

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xena_hernandez98•9d ago

Had to pick between a 3-jaw chuck and a 4-jaw for a weird brass part today

So I got this job turning a tiny brass piece that was totally out of round. Real tough call. I went with the 4-jaw because I could adjust each jaw individually to center it up. Took me like 20 minutes to get it running true but after that the cut was perfect. Would a 3-jaw have worked faster? Maybe but I dont think it would have held that close. Has anyone else spent way too long dialing in a 4-jaw for a simple part?

2 comments

noahwood•12d ago

Tried a 3/8 end mill with a bigger stepover than usual on some 6061 aluminum

I was running some parts for a side job in my garage last night and decided to push a 3/4 inch stepover on a 3/8 inch 3-flute end mill just to see what would happen. Normally I'd keep it at like 30% of tool diameter but I went up to 75% on the finish pass. The machine growled a bit but the surface finish came out way better than I expected with no chatter marks. Has anyone else messed around with bumping up stepover on aluminum and got weirdly good results?

2 comments

oliver_baker49•13d ago

Tried a 0.031 end mill on aluminum and learned the hard way about chip load

I was running a job last Tuesday on a little Tormach 440 and needed to cut a slot 0.035 wide in a 6061 part. Figured I'd just grab a 0.031 two flute carbide end mill and send it at 12000 RPM with a 10 IPM feed like I do with bigger tools. First pass sounded fine but on the second pass the tool snapped clean off about halfway through the slot. Turns out I wasn't clearing chips and the flutes packed up solid. I slowed the RPM down to 8000 and dropped the feed to 6 IPM with a peck cycle every 0.005 and it finished the rest of the part no problem. Has anyone else had success with tiny end mills on aluminum using a different strategy? I'm thinking about trying a single flute next time to get better chip evacuation.

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paige_bell81•14d ago

Old timer at a shop in Toledo called me out for rushing

I was cranking feeds and speeds on a stainless job to hit a deadline and this guy with 40 years in walks over. He just pointed at my chips turning blue and said 'you're gonna trash that insert in 10 minutes' - sure enough, 8 minutes later it shattered. Has anyone else had a veteran save them from a stupid mistake on the floor?

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parker_webb•14d ago

Had a collet chuck let go at 12k rpm this morning

Scraped the part, blew out the tool holder, and scared the hell out of me. Think the drawbar wasn't tight enough but I've been running this setup for months with no issues. Anybody else had a collet slip on them out of nowhere? What did you find was the cause?

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nathan_kim•15d ago

Tool path collision wrecked my spindle - was it my programming or the CAM software?

Yesterday morning I ran a 3D contour on some 6061 aluminum and the tool plunged straight into a clamp, sheared the endmill and probably knocked the spindle out of tram, so now I'm trying to figure out if I missed a clearance move in the setup or if Fusion 360 just decided not to show that interference on the simulation - anyone else have this kind of screw-up and how did you narrow down the cause?

3 comments

rowan_ross•1mo ago

Hit 500 hours of spindle runtime on my old Haas last week and honestly I didn't think it would still hold tolerance that tight.

Pulled a 0.0005" tolerance part after that milestone and it came out dead nuts, has anyone else seen their machine stay this consistent past the 500 hour mark?

3 comments

adam414•1mo ago

Spent 4 hours chasing a tool offset issue that was just a loose screw...

I was running a part in a HAAS VF-2 last Tuesday and the Z height kept drifting by like .003 every cycle. Spent two whole afternoons re-checking my program, re-setting offsets, even called a buddy for help. Turns out the set screw on the tool holder was just a little loose from a crash 2 months ago. Anybody else ever spend way too long on something that stupid simple?

3 comments

taylor.brooke•1mo ago

Had the worst crash week of my 8 years running CNC

Three machines down in four days last February. Spindle seized on the Haas, then the coolant pump failed on the Mazak, and a tool changer jammed on the Okuma. Anyone else have a stretch where everything went wrong at once?

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henryr45•1mo ago

Stop using default tool paths on aluminum and wondering why your finish looks bad

I keep seeing guys at my shop in Houston running standard pocket routines on 6061 and then complaining about chip welding and rough edges. Why would you run the same feed and speed you use for steel on something that gums up instantly? I switched to a climb milling path with a .002 chip load and some air blast, and my parts come out looking like glass now. Took me about 3 tries to dial it in but the finish quality jumped way up. Has anyone else seen a big difference just by changing your approach direction?

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kimr91•1mo ago

Watched a guy at a shop in Detroit set up a 5-axis in 15 minutes flat

I was over at a friend's shop last month in Detroit checking out their new DMG Mori. This older operator walks over, doesn't even look at the manual, and has the whole thing dialed in running parts in under 15 minutes. He told me he never trusts the auto probing and always does a manual tram first. I've been doing it his way ever since and my setups are way more consistent. Has anyone else dropped the auto routines for manual checks?

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ray613•1mo ago

Found a trick to stop my mill from chattering on thin wall parts

So I've been fighting with chatter on some stainless steel parts for weeks now. These are thin wall tubes about 0.040 inch thick and every time I tried to take a finish pass the whole thing would ring like a bell. I tried slowing down the RPM, tried different feed rates, nothing worked great. Then last Tuesday a older guy in the break room said try putting some rubber bands around the part before you clamp it. Sounds crazy right? But I grabbed a pack of thick rubber bands from the supply closet and wrapped two around the tube near the middle. It dampened the vibration almost completely. The finish came out way smoother and I didn't have to scrap a single part. Has anyone else used rubber bands or something weird like that for damping vibration?

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kellyallen•1mo ago

Question about speed vs precision that's been bugging me

Had a chat with my uncle last weekend who ran a manual machine shop for 30 years before retiring. He said something that really hit me. He told me I'm too focused on cycle times and that I'm missing the bigger picture. Said he once watched a guy crash a $50,000 spindle just trying to shave 2 seconds off a part. I always thought the faster I go, the more money I make. But now I'm wondering if that's really true for the kind of work I do. We run a lot of one-off prototypes here in Portland, not production runs. Has anyone else had to rethink how they balance speed against just not messing things up?

3 comments

kimdixon•1mo ago

Tried a used 1/2 inch collet off eBay - big mistake on a Friday run

Picked up a cheap collet for my Haas mini mill last week. First pass on a 6061 bracket showed .005 runout on the indicator. Anyone else get burned by worn tooling from resale sites?

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juliaa65•1mo ago

The way some guys ignore tool offsets is driving me crazy

I was at a shop in Denver last week helping a buddy with his Haas. This kid comes over to check his part and it's off by like 0.015. He just tweaks the program instead of checking his tool offset. I see this all the time now. Why would you mess with code when the offset is right there? It takes 30 seconds to touch off a tool properly. Has anyone else noticed how many guys skip the basics and chase their tail all day?

3 comments