Getting into machining is hard. From high-speed seel versus carbide to “old US iron” versus “new Asian manufacture” to simply choosing which drill bits to buy, many hard decisions must be made before one even has a chance to gain experience. Fear not, [Quinn Dunki] has created “a roadmap for how to get involved in this hobby.”
We saw [Quinn’s] first entry in her lathe series back in January, and now the series is complete! Starting with the definition of a machine tool and ending with the famous Clickspring scriber and a multi-material pen, [Quinn] leaves no stone unturned. [Quinn’s] style contrasts with the likes of [ThisOldTony], [AvE] or [Clickspring], as she makes sure to include the gory details of everything, citing her dissatisfaction with most YouTube machinists as motivation:
they’re all about the money shots of chips flying, but thin on the actual work of machining, which is mostly work-holding setups, changing bits and dies around, etc. That’s where all the knowledge is. The machine does the work once you spend 20 minutes setting it up properly for the operation. Everyone skips that part. I scour Tubalcain videos for details like the angle of the compound for a facing operation, or how to drill a deep hole with a short tail stock without the carriage getting in the way. Simple things like that get glossed over, but stump a beginner.
Of the series, our favorite part was “Grinding tool bits.” When combined with [ThisOldTony’s] Grinding HSS Tools, the two form an education in high-speed steel tool grinding fit for a hacker. Need more than high-speed steel? We’ve got you covered.
14 thoughts on “New Wisdom On Old Practices”
“high-speed seel” – Is that like Seal Team Six or the ones at Sea World? ;)
I believe it’s Seal singing a Cold Play song.
Might be a pokemon. Epic battle.
You guys should take a look at Frank Ford’s machining articles: http://www.frets.com/HomeShopTech/hstpages.html
Being just about an old guy, I hear from other old guys (and girls) how they’re finding that there are few younger folks willing to follow their footsteps into the trade.
Part of the problem is that there’s pathetic support for apprenticing. There’s much less job security for anybody, so it’s hard to mentor under those conditions. And few solid opportunities to apprentice, that will support a young person for long enough to gain the necessary experience. Both government and business are AWOL here.
Secondly… there’s been a general devaluing of manual work, even demanding trades like machining. Unions busted, no job security, lower pay… what young person would want to risk the commitment when the path is rocky and the rewards are uncertain?
It’s a pity, because today’s maker or hacker are prime material to become master craftspeople. I guess the only link is when tradespeople share their knowledge onnthe internet. I’m learnig arc-welding from such offerings.
First: I’m 50, so I almost qualify as an old guy. Second: Unions? Really? The only union reps I ever saw were not-at-all-disguised mafia, and they would close the business and throw a whole plant full of people on the street before they gave up one bit of perceived “bargaining power”. They were only serving themselves. As far as mentoring goes: too many older machinists were flat out bastards that wouldn’t give out anything but misinformation to protect their “trade secrets”. There are some old trade school manuals to be found, but it’s harder to find now that Lindsay Technical books is gone. Sometimes you can find them at estate sales, or used book dealers at flea markets.
Unions weren’t perfect, but the decline of unions and the decline of decent, secure trade jobs happening at about the same time is not a coincidence.
I looked through a couple articles. Couple things, a caliper is not a replacement for a micrometer. Calipers are very easy to get mixed up readings and never use the internal jaws to try and measure the ID of something round. The ID jaws have flats and will not read accurately, especially on small holes.
Do not use a center drill as a starting drill, use a spot drill. The angle is intended for a center and is too steep for standard drill bit which can catch an edge and start the hole off center. Also do not step up in sizes, drill to the size you want, there is no need for pilot holes. Redrilling holes can cause all sorts of problems like poor finish and out of round holes.
Modern carbides do not have a minimum speeds, some geometries and coatings do work better under high speeds and pressures but most wont care if you run them slow. I use DCMT/DCGT 21.51 inserts almost exclusively now on my lathe. I have left/right holders and have a solid carbide boring bar that holds them too. The DCGT inserts are a high positive and they machine nonferrous and plastics beautifully. They can be used on ferrous/stainless too if you are careful.
You can only drill without pilot hole if your drill has no “soul”. That is the point where all the cutting edges join in the tip of your drill. This point can not cut through material.
Oh you can, you just have to work it harder :)
I know what your trying to explain, there’s a web at the tip of a drill that doesnt have a cutting edge, if you make a pilot hole larger than this web, the drill will cut faster and easier.
Various drill point geometries reduce the need for this (split point and multi faceted grinds) which is what macona is suggesting, but I still drill a small starting pilot hole so I can save the part if something goes wrong with a end mill and a lot of fixturing work later on…
On the main vid, most youtube videos dont have the fixturing part because thats the really long winded boring bit of the operation…
Oh yes it can and will. Here is drilling 11/16″ holes with a standard 118 degree point, no pilot: https://youtu.be/fmYfMplqqXI
Best practice I ever had for machining and setting up was on a huge cylindrical grinder. Set the work up, make sure its sitting true and not off center in the manual 4Jaw chuck. Run a black felt tip pen over the surface and start to grind off just the felt marking and leave the metal un touched. The grinding wheel was about 1m in diameter on that machine.
Proper set up can save you so much time having to correct the work later or re-do the whole job. even things like surface grinding there you already have a flat surface needs a lot of prep to ensure your finish is going to be perfect every time. one pass too many even when you are at the correct height can take that too much off the surface or worse using the wring wheel for the job rears holes in the work that may not be viable but when you are trying to get a seal on the part for some reason it does not quite work.
FWIW, once I decided to actually measure the thickness of a sharpie mark with a profilometer, anywhere from 1.4um to 3um thick. .000055″ to .00011″:
A pretty decent intro to machining but if you want proper instruction videos then use http://thatlazymachinist.com. He takes you through all the details. Also has a YouTube channel: https://www.youtube.com/channel/UCOfQ4Ufy4s7GJB3h9VieY1Q He was a machining instructor at a community college.
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