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

lcamtuf.coredump.cx

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

#131

Post by rfrey »

gaze wrote: post #76
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…

The problem is that once you start adding up the cost of the components to make a capable CNC mill, you get really close to the price of existing ones. Ball screws, good linear rails, etc. are no joke. Big heavy castings (cast iron or polymer concrete) are no joke. The most "disruptive" maker-style machine is the Tormach and it's not well liked.

What you say is correct, except that a hobbyist can source parts from Ebay and the like. Which you could never do for a production machine. That can bring the cost WAY down.

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

#132

Post by donkeyofd00m »

digdugdirk wrote: post #106
donkeyofd00m wrote: post #95

Earlier quoted context omitted.

Lol sweet... so even you guys with highly dangerous stuff too Hey, my favourite jank tip: an O ring blew but you don't have a replacement? Bubble gum works pretty well for a few days

Okay, but maybe lets not share that particular tip with the dude who works on radiation equipment?

For tests on prototype subsystems like a cooling system? Totally fair game

Live full production systems? Usually no one will be willing to risk the OSHA or ISO violations where critical failure affects safety. Or, if they do, that company won't last long

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

#133

Post by s1artibartfast »

kragen wrote: post #121
s1artibartfast wrote: post #116

Earlier quoted context omitted.

Ah yes, it was hard for me to tell the difference even reading the spellings side by side. That said, it is definitely the weakest of the suggestions. The rest are serious books that a professional might refer back to. On the other hand you should really never need to refer back to a statics text, and it could be switched out for any number of options.

I really appreciate the recommendations. I have enough knowledge of the field to understand that control engineering and vibrational modes are extremely important but not enough to know what's most important to know about them or which books are more reliable or better written. What do you think about Reuleaux's Kinematics of Machinery and the Machinery's Handbook ?

I don't have experience with your kinematics book, and have some limited exposure to machinery's handbook. My impression of the latter is that it is good and highly regarded, but perhaps more on the Practical fabrication side then engineering Theory.

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

#134

Post by totemandtoken »

DalekBaldwin wrote: post #110
switchbak wrote: post #67

Earlier quoted context omitted.

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…

Yes, I was implying "to do stuff like the author of the article does" ( https://lcamtuf.coredump.cx/rstory/ ), coming from a very similar situation as him -- as a software engineer with an already broad general scientific and technical background, in a small apartment, getting into the concrete particulars of designing and building cool mechanical projects on a small scale and budget.

I mean, the last few lines I wrote still stand if that's what you want to do. I would learn some CAD software, download a few files and try to cnc or 3D print something. Even in that link, I saw a screenshot of some CAD software.

I personally use a Sainsmart 3020. It's relatively cheap and pretty small. For my goals, it gets what I want done. I used to have an Ender 3 Pro for 3D printing but had to give that up. If you want to get into the business of manually using a lathe or something, more power to you, but why when we live in an era of desktop manufacture? But regardless of what equipment you use, you need something that can inspect, possibly edit, and transfer the design file to the equipment i.e. CAD.

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

#135

Post by totemandtoken »

Rokid wrote: post #85
totemandtoken wrote: post #48

Earlier quoted context omitted.

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…

> The biggest difference I see between software developers and mechanical engineers is a way of thinking. Can you give an example? Myself being a mechanical engineer who also turned to software development, the people I talk to from SW are used to dealing with large matrices and semi-complex math. Sure they don't know about modal analysis or Navier–Stokes equations, but the lack of a certain way of thinking I cannot…

As the other comment and a few others have iterated, software guys don't have as much of a "measure twice, cut once" mentality. It's not so much about the math or technical knowledge, it's more of a mentality.

Let me put it this way - I've seen many times software engineers laugh when they encounter a funny bug or an output they didn't expect. I don't think I've ever seen an ME laugh when something breaks.

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

#136

Post by F35Machinist »

jacquesm wrote: post #104

This is a great guide. One word of warning: it's not the shop tools that will cost you real money over the longer term, it is the tooling. It isn't rare at all to spend double or more on tooling than you did on your CNC machine, especially if you bought it second hand. So keep a sharp eye out for local machine shops going out of business and ebay to score tooling in quantity, sort out what you think you'll need and s…

I wouldn't recommend buying anything other than brand new cutters. People overpay for used junk. New cutters can be pricey, but you only buy what you need anyway.

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

#137

Post by mmaunder »

I use a Shapeoko XXL 3 and 4 and I have a HDM on the way. The 5 Pro and migration to ballscrews for X and Y instead of belts for their more affordable machines looks great. Wanted to first say this is a great resource and I’ll be constantly referring to it. It doesn’t mention Fusion 360 and Vectric Aspire much so I just wanted to add that Fusion is great for engineering designs and CAM but is terrible at machining shapes derived from STL or other high resolution 3D data. Fusion likes you to create the source data in Fusion. It can’t handle creating CAM tool paths for scans with more than 50,000 triangles and even more than 10,000 is asking a lot. Aspire absolutely eats STL tool paths for breakfast and asks for seconds. So for machining topography I’ve moved entirely over to Aspire. I like it so much I’m using it for other non topo projects too because it’s just so fast. It is significantly slower on a Windows VM but absolutely screams along on a modest gaming PC. There’s a free tier for Aspire so try it out. To buy Fusion or Aspire is expensive which is why the guide probably doesn’t mention them much.

Also total tangent but I just installed a Fireboy automatic fire extinguisher above my CNC machine that I use for overnight unattended jobs along with cameras and remote shut off. I’d strongly recommend this for longer jobs. CNC fires are common and seem to be most often caused by insufficient work holding where the part comes loose and is dragged by the bit creating friction and heat.

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

#138

Post by mmaunder »

HWR_14 wrote: post #117

The information there seems to dismiss a lot of the dust considerations with regard to cncing standard (aluminum, wood, plastic) materials. Other sources online have been pretty scary. Does anyone have any experience or knowledge?

Most CNC machines come with a vacuum attachment which I recommend using. If your feeds and speeds are correct your making chips, not dust.

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

#139

Post by takk309 »

mmaunder wrote: post #137

I use a Shapeoko XXL 3 and 4 and I have a HDM on the way. The 5 Pro and migration to ballscrews for X and Y instead of belts for their more affordable machines looks great. Wanted to first say this is a great resource and I’ll be constantly referring to it. It doesn’t mention Fusion 360 and Vectric Aspire much so I just wanted to add that Fusion is great for engineering designs and CAM but is terrible at machining sh…

I watched a good video on the subject of adaptive clearing taking too long to calculate and it helped me to improve the processing and machining time of complex geometry.

https://youtu.be/osNPQr5-EpM

Another thing I found with topographic stuff is to simplify the mesh after importing it. It makes very little difference to the final project depending on your scale.

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

#140

Post by karmicthreat »

rspeele wrote: post #19
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…

Another problem is that really good CAD software is expensive. I have used FreeCAD. Its instability frustrated me. Not very rewarding to work on a part that needs a moderately complex feature like a loft, only to find out that after adding the loft FC crashes every few minutes so the part is essentially impossible to edit further. SolveSpace is much more stable but it doesn't have those complex features at all. You c…

Cad software has lots of options now. OnShape is another one that is cheap and pretty good.
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