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Hobby CAD, CNC machining, and resin casting (2015)

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Re: Hobby CAD, CNC machining, and resin casting (2015)

#51

Post by throwaway81523 »

throwaway81523 wrote: post #46
Animats wrote: post #40

Earlier quoted context omitted.

That's usually done with something called a rotary broach.[1] This is a clever trick. You first make a round hole. The rotary broach is a hex-shaped cutting tool. Both workpiece and tool are clamped in a lathe. But the center of the tool is slightly offset from the rotational center of the workpiece. Both spin, but the eccentricity makes it cut a hexagonal hole. Here's the process.[1] A milling machine can cut a hexa…

Thanks, yeah, a separate 4mm socket with a handle is certainly a possibility, but I liked the idea of a 4mm hex hole in something like this, to accompany the holes that are already there: https://knifeworks.com/crkt-9100kc-eatn-tool-black-oxide-fin... I'll look at the rotary broach video. Yes the hole would go all the way through, so a punch sounds ok. Anyway it's not about making this one hole. It's more an example…

Cool, thanks, yeah for a single hole, doing it by hand with a needle file sounds more practical. Does something like this seem CNC-able?

https://sakparts.com/products/can-opener-diy-tool-part-for-8...

The idea isn't to duplicate an existing can opener, but rather to make custom specialized tools to fit into a SAK, or replacement knife blades out of specialty knife steels (i.e. very hard, so probably difficult to machine). It wouldn't just be for SAK's but also for other folding knives, each with its own special cutting pattern to work with its pivot and locking system.

Titanium is another material of interest, for ultralight gear.

All of this is probably impractical at the hobbyist level with limited work space, though. Oh well.

Re: Hobby CAD, CNC machining, and resin casting (2015)

#52

Post by Animats »

throwaway81523 wrote: post #51
throwaway81523 wrote: post #46

Earlier quoted context omitted.

Thanks, yeah, a separate 4mm socket with a handle is certainly a possibility, but I liked the idea of a 4mm hex hole in something like this, to accompany the holes that are already there: https://knifeworks.com/crkt-9100kc-eatn-tool-black-oxide-fin... I'll look at the rotary broach video. Yes the hole would go all the way through, so a punch sounds ok. Anyway it's not about making this one hole. It's more an example…

Cool, thanks, yeah for a single hole, doing it by hand with a needle file sounds more practical. Does something like this seem CNC-able? https://sakparts.com/products/can-opener-diy-tool-part-for-8... The idea isn't to duplicate an existing can opener, but rather to make custom specialized tools to fit into a SAK, or replacement knife blades out of specialty knife steels (i.e. very hard, so probably difficult to mach…

DIY knife forging is common. Search "knife forging". Look around for classes and forges with training. There's a huge amount of info on knife making and metallurgy. People obsess on this stuff. A good knife is a trick of metallurgy. The blade must be hard at the edge to be sharp but ductile in the body so as not to be brittle. How to do this is well understood today, but there was much mystery around it for centuries. If you're fascinated by metalworking, but don't have to make machine parts, that's a hobby direction.

Victorinox knife manufacture.[1] Stamp, heat treat, grind, polish. They're not exotic blades, just good manufactured stainless steel parts.

A primer on machining titanium.[2]

[1] https://www.popularmechanics.com/adventure/outdoor-gear/a351...

[2] https://www.harveyperformance.com/in-the-loupe/titanium-mach...

Re: Hobby CAD, CNC machining, and resin casting (2015)

#53

Post by [deleted] »

mdorazio wrote: post #13
sottol wrote: post #5

Shameless plug if anyone is interested - I'm working on a $600-ish open-source, reasonably capable, but small and somewhat "tidy" hobby CNC machine with BOM cost around $600 that requires some DIYing. It's meant to be an alternative to the Desktop CNCs like Nomad, Carvera, Bantam, ... moreso than a PCNC or other proper entry-level CNC. The ultimate goal is to make it hobbyist-friendly, capable of easily cutting alumi…

What's the advantage of this over a 3018 or 3030 machine? With some basic upgrades (you mentioned needing to diy anyway) you can easily cut aluminum on those for $500 or less.

[deleted]

Re: Hobby CAD, CNC machining, and resin casting (2015)

#54

Post by throwaway81523 »

Animats wrote: post #52
throwaway81523 wrote: post #51

Earlier quoted context omitted.

Cool, thanks, yeah for a single hole, doing it by hand with a needle file sounds more practical. Does something like this seem CNC-able? https://sakparts.com/products/can-opener-diy-tool-part-for-8... The idea isn't to duplicate an existing can opener, but rather to make custom specialized tools to fit into a SAK, or replacement knife blades out of specialty knife steels (i.e. very hard, so probably difficult to mach…

DIY knife forging is common. Search "knife forging". Look around for classes and forges with training. There's a huge amount of info on knife making and metallurgy. People obsess on this stuff. A good knife is a trick of metallurgy. The blade must be hard at the edge to be sharp but ductile in the body so as not to be brittle. How to do this is well understood today, but there was much mystery around it for centuries…

Sure, knife forging is one thing, but the idea of making replacement blades for folding knives sounds like it takes machining, because of the weird shapes needed at the pivot end, especially for weird locking mechanisms. It would be nice to be able to do that at a semi-commercial level if one were to get into it at all. Victorinox is on a completely different scale, making millions of units of whatever. But forging is for making one or two of something, while CNC machining is interesting for making a few hundred.

In practice I don't have it in me to pursue something like that for real. It's just interesting to find out about.

If I simply wanted to make knives, then no machining would be needed, just some cutting discs and belt sanders. It's the specific thought of making replacement blades for existing folders that seems to want more automation. I guess there are existing shops that can do that type of thing from a CAD drawing though.

Re: Hobby CAD, CNC machining, and resin casting (2015)

#55

Post by kragen »

mionhe wrote: post #48
blackeyeblitzar wrote: post #47

Earlier quoted context omitted.

Have you tried metal 3D printing? Is that a thing for home hobbyists?

Those machines are still really expensive, and I haven't seen any versions that aren't a giant pain in the rear to setup and run. (spent several years setting up and rubbing prints on metal 3d printers.)

Which 3-D printing process were you using, and why did you rub the prints?

Re: Hobby CAD, CNC machining, and resin casting (2015)

#56

Post by WillAdams »

Joel_Mckay wrote: post #27
WillAdams wrote: post #26

Earlier quoted context omitted.

I use mine in my (finished) basement, or if cutting tropical hardwoods out on my back deck (I have a machine on a wheeled cart).

The noise from having a router and vacuum dust-collection running all the time can become a problem in residential areas. Most would like a full-sized machine that could directly handle standard sheets of material, but the space is not the only limiting factor (i.e. the insurance provider could pull something nasty with your mortgage creditors etc.) Peoples situations will differ, and definitely check out reverse-spi…

While everyone wants a machine for full-sheets of plywood, they're expensive, and not used for many projects --- a smaller machine suits most needs and there is always tiling.

My machine is quieter than my neighbor's drum kit --- and I've run mine after 11PM and you can't hear it over traffic and the nearby speedway (on race night) outside in the yard (a quiet vacuum helps a lot), but I have gone over to their house at 11:01 PM to remind them of what time it is.

Re: Hobby CAD, CNC machining, and resin casting (2015)

#57

Post by hereonout2 »

syntaxing wrote: post #7

Former MechE for a decade and I owned personal CNC routers and on my 6th 3D printer. The biggest issue with CNC is the cost for consumables and accessories. Need a special bit? $$$ Need stock to cut? $$$ Want a nice ER11 or R2 collet set? $$$. A nice vise? $$$ Cut something wrong with a carbide bit? Shrapnel explosion. 3D printing has a bunch of limitations but is a way better machine for hobbyist. But I have been ey…

There's a much higher barrier to entry with CNC. I have a cheapo CNC - few hundred dollars - and really have only ever made one practical usable "thing" on it.

It's so slow and needs much trial and error to get a decent cut, I feel a more expensive machine would be much more versatile but cost 10x for the machine and consumables as you say.

With the similarly priced 3d printer I feel like I've actually saved a lot of money and hassle printing things. I can quickly download a model and print a perfectly useable "thing" in no time, often with no mistakes. Prusa slicer and a larger $5 nozzle has made things even better, even though I have an off brand 6 year old printer.

Lots of hobbies can get expensive though, especially when high quality tools are involved. I'd actually argue 3d printing is an exception to that.

Decent power tools and consumables rack up and don't even look at the price of hand tools from the likes of Lie Nielsen.

Re: Hobby CAD, CNC machining, and resin casting (2015)

#58

Post by eth0up »

To the machinist/s here:

For nearly a year, I've been contacting local machinists for a small[*] project which involves 1) an accurate cut on both ends of a 17" billet of T6061, 2) two crescent cuts, 3) up to 8 threaded holes, but probably, 4) a wee bit o end shaping.

All the aesthetic contours, shaping and weight reduction I'd do manually - I hand machine bronze, aluminum and wood archer's thumb-rings, so can wangle that part.

This project would result in the world's first ILF asiatic (no shelf), ambidextrous aluminum 17" riser.

Though... Every machinist I've spoken to is either friendly at first, implying willingness and ready capabilities, or they simply say no thanks. But all of them ultimately reject the task, typically saying they're too busy.

I also have a design for a bow stringer that can handle longbows, recurves and short Asiatic bows safely and efficiently. No one will fabricate it around here.

Any suggestions as to why this is such a pariah project? Any suggestions on how I might achieve this?

* Not necessarily a good reason/excuse

Re: Hobby CAD, CNC machining, and resin casting (2015)

#59

Post by bluGill »

throwaway81523 wrote: post #51
throwaway81523 wrote: post #46

Earlier quoted context omitted.

Thanks, yeah, a separate 4mm socket with a handle is certainly a possibility, but I liked the idea of a 4mm hex hole in something like this, to accompany the holes that are already there: https://knifeworks.com/crkt-9100kc-eatn-tool-black-oxide-fin... I'll look at the rotary broach video. Yes the hole would go all the way through, so a punch sounds ok. Anyway it's not about making this one hole. It's more an example…

Cool, thanks, yeah for a single hole, doing it by hand with a needle file sounds more practical. Does something like this seem CNC-able? https://sakparts.com/products/can-opener-diy-tool-part-for-8... The idea isn't to duplicate an existing can opener, but rather to make custom specialized tools to fit into a SAK, or replacement knife blades out of specialty knife steels (i.e. very hard, so probably difficult to mach…

Knifes are done with heat treating. you need to get the steel red hot and follow the proper cooling process. You machine soft iron to close then make it too hard to machine, finally grindit to the perfect size.

Re: Hobby CAD, CNC machining, and resin casting (2015)

#60

Post by imtringued »

99_00 wrote: post #14

It’s hard for me to believe that using a CNC to mill a model for resin casting works better than 3D printing it and casting it. I’d expect that with 3D printing you can even print the spruce and risers.

It is possible to get good results with 3D printers, but that requires you to go to below than 0.1mm layer heights with 0.1mm nozzles and nobody has time for that. You can make a hundred resin parts in the time it takes for the printer to finish making one.
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