when you mill into your first piece of steel on your own - Page 1
Forum section: electronics / general

author: SparkyFX
author_rank: Frequent Contributor
timestamp: July 02, 2019, 07:23:59 am
content: You break the endmill because the speed and feed was wrong... or it chatters like crazy because you forgot to clamp an axis.

author: thinkfat
author_rank: Unknown
timestamp: July 02, 2019, 09:42:11 am
content: You run your endmill into the vise because you accidentally engage the fast feed.Gesendet von meinem Nokia 6.1 mit Tapatalk

author: Rerouter
author_rank: Super Contributor
timestamp: July 02, 2019, 09:57:05 am
content: you count to 3 before watching the machine hard stall the endmill into the XY tableI started on wood and v-cutter bits to get a feel for things before starting with metal, its a very different beast,I will say the longing for more power gets very real very quick, Oh you want to plane this surface? well your motor is only 3KW with X top speed, so your limited in feed rate. Oh compensate with a smaller cutter diameter? that will increase the part time by about 3 times. etc

author: Dubbie
author_rank: Unknown
timestamp: July 02, 2019, 10:12:27 am
content: 3 KW is a very respectable spindle. What are you trying to do? Use a 4” shell mill?

author: Rerouter
author_rank: Super Contributor
timestamp: July 02, 2019, 10:53:29 am
content: well 3KW at about 1000RPM, It drops off the faster you go, and one of your mentors decides to be a .... and gifts you a carbide insert 1" shear hog that chatters unless it has an unreasonable depth of cut to celebrate the new mill. I know a fly cutter would be better for my example, But never gotten around to buying one because they seem too easy to build, but equally never built one.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 02, 2019, 11:08:07 am
content: good myth fiction in the OP. this is not ee related and hence should be in General section.

author: noidea
author_rank: Unknown
timestamp: July 02, 2019, 12:09:49 pm
content: This was about 35 years ago I was about 13 or 14 and decided to have a muck around with the Bridgeport at my Dad's factory and smashed a brand new end mill. Dad comes out of the office and says you've just learnt a lesson in why climb milling is a bad idea, please try not learn it again cutters are expensive......Go forward a few years and you are helping out during holidays making parts on a Heckert mill and manage to R/T a side and face mill into the workpiece and turn it into shards of HSS because you couldn't get your head around the weird button setup to engage the feeds, it also had only had one handwheel you had to keep changing around to manually traverse or feed it. I was forever $h!tscared of it after that (maybe why I ended up a HVAC tech and not a tool and die maker!)

author: duak
author_rank: Super Contributor
timestamp: July 02, 2019, 06:01:27 pm
content: The "Feeling of Power" and "Man, the Toolmaker" all rolled up into one?I retired about ten years ago and when people found I had time on my hands I got drawn into repairing a few old CNC machines that weren't supported by their manufacturers any more.The picture shows what happens when the wrong tool gets selected from the tool changer. The program called for an end mill but it got a drill chuck instead. The material is aluminum and didn't stall the spindle or the axis servo so it melted the part - it didn't do the chuck much good either. The cause of the problem was that the tool carousel could often slide to the next position because over the years mechanical friction had actually lessened.When machining steel there's an interesting effect called Adiabatic Shearing. Basically, if you hit the material hard and fast enough a soft layer forms along the shear line and the tool then wipes the chip off the workpiece. Oddly enough, it reduces the power required but you need a strong and stiff machine without any play in the ways. I first ran into this when I got an old Mitsui machining center built in 1984 working again. The owner chucked up a piece of hot rolled mild steel and hit it with a face mill turning about 8000 RPM. There were red hot chips shooting about 20 feet out the top but it was only using about half the spindle horsepower it would have if it went at half the speed. I was used to manual mills and there was no way I would gone anywhere as fast as that. The owner said that it was the best way to get under the hardened skin of the material - if you pussyfoot it, the inserts grind their way through and that's a lot harder on them.

author: KL27x
author_rank: Super Contributor
timestamp: July 07, 2019, 11:15:11 pm
content: And then you check the current price of steel, andI don't have a steel-capable mill, but unless I had combustion engines or heavy equipment to maintain, I can't imagine needing one more than once every year or three. ToT is my favorite Youtuber, but I have never seen use of a mill that made me interested for even a second to have a basement or garage cluttered with 1+ tons of lathes/mills/surface grinders/shapers.If you want magic, try turning steel in a drill, cutting it with nothing but grinders and burrs and stones and files. You can do sub 1 mil work like that. You can make a variety of bushings, axles, tool posts, dies, and whatnot. Most of the super precision stuff you might ever need - bearing, rails, gears - you can actually just buy cheaper than you could ever make.If you want super magic, work with wood. The reason metalworkers hate woodworking is because it's cheating. If they could mill steel they way you can route wood with a 5 lb handheld plunge router, they would pay a million dollars for that.I imagine if you own a mill that is not used directly for profit, you also own and operate at least 1 tractor or some other industrial heavy equipment, or you like to tinker with firearms or combustion engines, or you have a really expensive hobby.

author: Dubbie
author_rank: Unknown
timestamp: July 08, 2019, 01:32:50 am
content: Quote from: KL27x on July 07, 2019, 11:15:11 pmI'd like to see that....The only way I could see that happening is if you decide on the measurement you want to hitafteryour part is finished.The price of steel is the absolute last thing you should worry about. It's easy to scrounge scrap steel from all over the place. You don't have to buy it shiny new straight from the mill. Most engineering places will give you drops or bits from the scrap bin for free if you ask nicely.

author: KL27x
author_rank: Super Contributor
timestamp: July 08, 2019, 01:44:45 am
content: You sneak up on it.Use the high speed grinder with cutoff, where you can. You may have to reverse the drill to oppose the grinder depending on what angles you have available. To make inside cavities, you can use burrs or small stones. You obviously can't do all the same things you could do with a boring bar, of course.You don't have to get a perfect surface. You'll leave ridges. That doesn't matter at this stage; you're just roughing it out. You just want to get your low spots to the right depth by sneaking up on it, and checking with calipers.Then switch to something like sanding block or file to take down the high spots and get relatively flat/round surfaces and to finish inside corners.It's more a matter of patience. It's like working with hand tools. You use your eye and you make things fit. You just have to get it right, once, near the end. You need a good drill with very low runout and high speed grinder so that the grinding remains concentric rather than being influenced by imperfections in the surface of the workpiece. (I have a very concentric and heavy and smooth drill that I use for 2 things... drilling holes in concrete and turning small parts. IME, cordless drills are all bad with runout, no matter how many hundreds $ you spent on the name.)A lot of the times you need to mate a steel surface, it doesn't have to be 100%, either. It may need just 2 or 3 rings or areas of contact, and low spots here and there may not even matter.Here's one tiny example. The original pin had enough slop to theoretically make the disconnector reset the trigger earlier than usual, not that I ever experienced a problem. It was visibly worn and loose. This hardened tool steel replacement pin has a smooth surface and a pretty crisp inside corner under the head. With calipers, I measure 158 thousandths OD of the shaft everywhere except the last 1/16" inch that measure 157 1/2. As far as I would guess, that bit of taper was intentional. But it was so long ago I made this that I can't say for sure. Notice that in person, the taper is very obvious to the eye, and it's less than a thousandth. I've done much larger and more complex parts, close to half inch stock, but they would take more work to disassemble and/or need to be recalibrated after reassembly.The other side gives a hint of what I turned it from. You can just make out a hexagonal shape that would be the right size to fit in a hex bit driver. Maybe not so good in the pic, though.It fits so tight, I had to work the trigger while removing it, and it was a bugger to get back in. It almost completely removed the problem, but there's still too much slop/wear somewhere else.Another thing I've done a few times is to grind down the shank of a steel bit from 1/4" to 6mm. Either because I could not obtain the bit in 6mm, which is relatively easy to change. Or because I had a 1/4" bit that wouldn't seat straight. That takes more work to get right.Grinding a morse taper with an angle grinder?Here, he uses a stone and a jig to true a table saw arbor. I bet it is easier to use a grinder and a cutoff disc to graze off the high spots, first. Then finish with a sanding block. You don't need a rigid setup when using a high speed grinder, and once it's grossly even (but rough and with some minor local unevenness), it will finish straight from there with a file or rigid backed abrasive. If there are low spots that are in a spot where it matters, just touch it up with the grinder to the chase out those low spots and try again.50 years ago, lots of precision stuff was hand ground with die grinders and eyeballs were much more important. This was a skilled job in demand at one time. And it's really not that hard. With a grinder and a drill/lathe, you can make pins/axles, bushings, punches/dies. You can cut O-ring or circlip grooves in a round. If you are really patient, you could cut gears and finish with a file, ala Clickspring. It might take a lot of time, but compare how many times a decade you might want to invent a reason to use your mill vs the time (and space and sweat equity) to move and setup heavy machining equipment. I'm sure everyone with a mill is just brimming with inventions they make on the spot, daily, rather than using a mill to churn out hundreds/thousands of the same thing day in/out for business and/or to maintain/service some machines they use for business.Anyone who has followed AvE's adventures with his $400,000 5 axis mill might be curious when he's going to actually use it to make something beyond a grill that doubles as a welding table or a fancy crowbar. I'm pretty sure the plate steel was flat enough to cook a hamburger the way it came from the supplier, and I'm certain you could have drilled and filed and ground a crowbar attachment by hand quicker than you can do it on a mill. Unless you think you're gonna make/sell "a lot" of 'em? $400,000 worth of your special widget.