Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Guerrilla guide to CNC machining, mold making, and resin casting (2015)

lcamtuf.coredump.cx

Post reply on HN
Print view View original

61–70 of 162 posts

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#61

Post by mbustamanter »

totemandtoken wrote: post #48
DalekBaldwin wrote: post #33

As somebody trying to get into mechanical engineering while living in a small urban apartment, this has been an incredible resource... not that I've made much progress along the lines it describes though. It's tough to plan a path toward growth in these skills without sustaining inordinate expenses at each step. I can't afford to become afflicted with Gear Acquisition Syndrome. I've come close to dropping huge sums o…

I was a mechanical engineer before I shifted to software development (so kind of the opposite of you) and I think you need actual, full on college level schooling to be a mechanical engineer in most cases. The stuff you're focusing on - basically manufacturing techniques - is a very small part of engineering in general. I didn't see any mention of CAD or FEA work, but even assuming you do know some of that or can acc…

Can I ask you a couple of questions? I am in a patricular situation, I'm a mathematician who does FEM and I think my training has been too abstract. My most recent work involves programming custom code in C++ for the study of buckling of thin shells (finite element method, continuum mechanics, differential geometry of shells, and all under the umbrella of functional analysis). Still the region I live in has virtually no relevant positions for FEA, which prompts me to ask:

(1) I've been thinking of getting a certification in ANSYS or Abaqus (it's relatively cheap). Would it help if I get some certs, or would it be enough to have expertise in several open source finite element programs? - think deal.ii, PETSc, MFEM, MOOSE, FreeFEM, FEniCS and the like. I really like to use the latter because apart from being free, they give me more freedom and I can use them with parallel computing on UNIX machines.

(2) Regarding manufacturing and machines/machining, any book or resources that stood out? I'm most familiar with the Machinery's Handbook.

(3) For design, did you use a tablet? I've been looking into buying one and use it for design, preferably with FOSS. Any recs?

Thank you for your comments,

M.

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#62

Post by RobotToaster »

dymk wrote: post #11
legitster wrote: post #6

Semi-related: As an average consumer I'm disappointed that nearly a decade of the "makerspace" has seemingly failed to produce any sort of meaningful Renaissance in small-scale US manufacturing. I've purchased the odd 3D printed or resin cast tchotchke from small operations a few times at this point. But it's still disappointing that if you need professional quality products, you still either need to pay out the nose…

It depends on what you mean by a renaissance of small-scale manufacturing. I see CNC and 3D printers much more often now in prosumer and small-business shops. People are making professional quality casts, with some work. Yes, it's effort, but it's going to be effort regardless of if you outsource the work, or learn how to do it the right way yourself. Plastic injection machines can be a few grand on eBay now. A very…

>"Maker youtube" has been popping off for years. People love small shops and DIY.

People love watching small shops and DIY, not actually doing DIY, or paying small shops.

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#63

Post by Animats »

DalekBaldwin wrote: post #33

As somebody trying to get into mechanical engineering while living in a small urban apartment, this has been an incredible resource... not that I've made much progress along the lines it describes though. It's tough to plan a path toward growth in these skills without sustaining inordinate expenses at each step. I can't afford to become afflicted with Gear Acquisition Syndrome. I've come close to dropping huge sums o…

> Maybe I'll visit a makerspace? Ah, but every one in my area appears to have gone defunct since Covid year zero.

Yes. I miss TechShop, where I did CNC machining. It's not all that difficult. Maybe 100-200 hours to minimal competence.

What's left of the maker movement seems to have been taken over by little old ladies into crafting. Gluing construction paper and macrame, not machining and welding. Activities classes for middle schoolers where they assemble kits, not original work. In the early days of TechShop, it was people making rocket engine nozzles for the X-Prize, and people who commuted to Shenzhen to get their stuff made in volume. Four Bridgeport mills, all going at once.

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#64

Post by michaelt »

bsder wrote: post #50
digdugdirk wrote: post #18

Earlier quoted context omitted.

I love your optimism, and would absolutely love to have this capability in a garage. But as someone who designs physical products (and deals with all of the manufacturing techniques you mentioned above on a regular basis) I can't say I agree. There's a huge amount of knowledge and skill required to make machined/cast/extruded metal components, and a very steep learning curve before someone can do so safely. Gamechang…

> Gamechanger? Yes. But likely mostly for the ambulance industry. While I laughed, I don't find this to be very true at all for working in metal. Working on metal seems to have WAY fewer injuries than people who work on wood. Metal working is almost always in a vise and your hands are on levers/cranks--away from the cutting surface. Whereas, with woodworking, your hands are almost always the motive force and directly…

I don't know, I'd have thought the angle grinder - signature tool of the metalworker - is probably one of the most dangerous tools you'll find in the average DIYer's garage.

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#65

Post by tgsovlerkhgsel »

throwaway4aday wrote: post #8

I think CNC machining is primed for developments that make it much easier to use for the home hobbyist. The tech is very close to what's needed for 3D printing but it has a few added requirements like the need for a sturdier frame and accommodations for a fairly large and powerful motor. Both are solvable with the right materials and the motor can be anything from a DC spindle to a repurposed wood router. The biggest…

One major difference between 3D printing and CNC is that 3D printing is standardized and simple enough that the steps from a 3D model to a printout are mostly automated. The workpiece is held by sticking to the print bed, print paths are autogenerated and layer by layer.

With CNC, you have to figure out how to hold the workpiece, often with multiple setups (which have to be done precisely), machining strategy (toolpath design) is non-trivial and depends on the exact tools you have (so not trivially automated), and it requires quite a bit of knowledge to properly design a toolpath.

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#66

Post by Max-q »

DalekBaldwin wrote: post #33

As somebody trying to get into mechanical engineering while living in a small urban apartment, this has been an incredible resource... not that I've made much progress along the lines it describes though. It's tough to plan a path toward growth in these skills without sustaining inordinate expenses at each step. I can't afford to become afflicted with Gear Acquisition Syndrome. I've come close to dropping huge sums o…

Just buy a Snapmaker. Then you can mill, print and laser cut with one small machine.

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#67

Post by switchbak »

totemandtoken wrote: post #48
DalekBaldwin wrote: post #33

As somebody trying to get into mechanical engineering while living in a small urban apartment, this has been an incredible resource... not that I've made much progress along the lines it describes though. It's tough to plan a path toward growth in these skills without sustaining inordinate expenses at each step. I can't afford to become afflicted with Gear Acquisition Syndrome. I've come close to dropping huge sums o…

I was a mechanical engineer before I shifted to software development (so kind of the opposite of you) and I think you need actual, full on college level schooling to be a mechanical engineer in most cases. The stuff you're focusing on - basically manufacturing techniques - is a very small part of engineering in general. I didn't see any mention of CAD or FEA work, but even assuming you do know some of that or can acc…

I read this as the OP was wanting to dip their toe into "making", not to do some self-directed learning such that they'd call themselves a MechE. Schooling would be great of course, but if your goals are very modest, I think what the OP has in mind might be fine too.

It'd be like telling someone fooling with Python that they need to take a full CS degree otherwise they'll fail to appreciate the beautiful mathematical underpinnings of functional programming. That might be true, but that's also not the goal.

Edit: clarification

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#68

Post by switchbak »

Animats wrote: post #63
DalekBaldwin wrote: post #33

As somebody trying to get into mechanical engineering while living in a small urban apartment, this has been an incredible resource... not that I've made much progress along the lines it describes though. It's tough to plan a path toward growth in these skills without sustaining inordinate expenses at each step. I can't afford to become afflicted with Gear Acquisition Syndrome. I've come close to dropping huge sums o…

> Maybe I'll visit a makerspace? Ah, but every one in my area appears to have gone defunct since Covid year zero. Yes. I miss TechShop, where I did CNC machining. It's not all that difficult. Maybe 100-200 hours to minimal competence. What's left of the maker movement seems to have been taken over by little old ladies into crafting. Gluing construction paper and macrame, not machining and welding. Activities classes…

I haven't checked into a makerspace in a while, and it's sad to hear that's where it's gone (for you at least).

Then again I live in the (relative) boonies, so the closest I'll come to a makerspace is what I stick in my garage :)

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#69

Post by Animats »

throwaway4aday wrote: post #8

I think CNC machining is primed for developments that make it much easier to use for the home hobbyist. The tech is very close to what's needed for 3D printing but it has a few added requirements like the need for a sturdier frame and accommodations for a fairly large and powerful motor. Both are solvable with the right materials and the motor can be anything from a DC spindle to a repurposed wood router. The biggest…

> repurposed wood router.

I've seen successful CNC machines which used a Bosch router as the spindle. The bearings were good enough, the motor could maintain speed as the load varies, and there was a strong round metal case you can mount to the XYZ drive. Brass and soft aluminum could be machined.

Steel, no. Milling metal, you're supposed to cut, not grind. Underpowered metal cutting means you can't take a big enough bite. If you're making metal dust, not chips, you're doing it wrong. It takes forever to do anything and you wear out cutters. I saw a video of someone making a key on a underpowered mill intended for jewelry, and it took an hour to cut a key out of brass. That should take about a minute.

Dremel tools will not work for CNC. The speed drops under load, the bearings wear out fast, and the plastic shell is not rigid enough. I've seen it tried.

Re: Guerrilla guide to CNC machining, mold making, and resin casting (2015)

#70

Post by prova_modena »

bsder wrote: post #50
digdugdirk wrote: post #18

Earlier quoted context omitted.

I love your optimism, and would absolutely love to have this capability in a garage. But as someone who designs physical products (and deals with all of the manufacturing techniques you mentioned above on a regular basis) I can't say I agree. There's a huge amount of knowledge and skill required to make machined/cast/extruded metal components, and a very steep learning curve before someone can do so safely. Gamechang…

> Gamechanger? Yes. But likely mostly for the ambulance industry. While I laughed, I don't find this to be very true at all for working in metal. Working on metal seems to have WAY fewer injuries than people who work on wood. Metal working is almost always in a vise and your hands are on levers/cranks--away from the cutting surface. Whereas, with woodworking, your hands are almost always the motive force and directly…

It really depends on what area of industry you are in and the safety culture of the shops you are around. I hear a lot of stories of really bad safety practices in metalworking. Including the exact inverse of your statement about machinists/woodworkers and missing fingers. I would also argue that accidents with common machine shop tools like lathes and mills may have higher consequences than your average table saw or jointer in a cabinet shop. The "potential energy" is higher so to speak, although I'm not trying to downplay the forces involved in something like a table saw kicking a workpiece back. For example, there's a prominent post on r/machinists now where a poster witnessed their coworker getting sucked into a lathe (fatally). This is not something that is a risk at most cabinet shops, but is a risk at most machine shops. That accident was indirectly caused by disabled safety interlocks on the lathe, an unfortunately common practice in the industry. All anecdotal evidence, of course, but I think machine shops have a different risk profile that isn't necessarily less risky overall.
Post reply on HN