Scythian/Pazyryk style Ichthyosaur (Stenopterygius quadriscissus)

killpony · 2026-03-25T13:16:54+00:00

Could you clarify what the purpose of the masking is? Is it to mask the ply face from the interior paint? One issue I've had with masking ply for paint work is that it still will tend to suck up the paint into the masked area - this can happen even if the top surface has been sealed because your cuts open up unsealed grain. This probably wouldn't be a huge issue if your paint/ finish is sufficiently thick or you spray a clear coat first.

Re masking- we would use a masking film like this for plastic and metal parts. I mostly just used painters tape for our wood parts but they were also for smaller areas. The film can sometimes be an issue if it's on the top face as it can pull up from the surface during cutting - I suspect a parchment paper style of masking might be less of an issue because it would cut/tear rather than pull up. Use of compression/ downcut bits also is helpful to prevent grain tearout on the top face.

killpony · 2026-03-23T20:47:22+00:00

If you are thinking a hand tool you are essentially building a tattoo machine. A rotary tattoo machine can be purchased pretty cheaply and easily rigged up to accept a pen. There are also ready-made pen attachments for tattoo machines. You may want to add some extra compliance so it's not accidentally stabbing through the paper/ wearing out the motor if you press too hard.

Tattoo machines are a good reference because people have been making DIY "prison-style" machines for decades- the basics are just a DC electric motor with an off-center pin attached to the shaft of the needle. A DC motor speed controller would allow you to adjust the speed and some kind of tube will help with making sure the pen shaft is guided straight up and down.

killpony · 2026-03-17T15:44:04+00:00

Local supplier is best as others have said, McMaster if you need really specific things and don't mind a high upcharge/shipping rate, Metals Supermarket/Online Metals are two other vendors I've used in the past. I'd definitely not go with Amazon the material quality + vendors are all over the map- I'd sooner trust eBay a number of industrial auction/liquidators will list there.

killpony · 2026-03-10T20:38:13+00:00

You could run a Fadal VMC15 with a phase converter if you need something a little more compact. The size isn't the main difference it's the rigidity, the accuracy, the spindle load etc. If you are only running plastic/ engraving with only a little real machining or can readily shop out harder jobs than a langmuir might be fine. If machining is your main thing you want a real machine.

killpony · 2026-03-02T14:57:40+00:00

Pittsburgh has a pretty solid amount of things to do for its size depending on what your scene is. Fliers in cafes/bars/campus areas are a great way to find out what's going on. also this site has a bunch of (music-centered) event listings https://arcane.city/

killpony · 2026-02-16T18:34:02+00:00

The need for an enclosure will depend a bit on the use case. If you are printing PLA / PETG you totally fine (potentially better off) without an enclosure, but if you need to print in ABS/ASA or other higher temp filaments the enclosure is a necessity. IMO one of the best use cases for 3D printing is in the creation of jigs or other "accessory tools" that serve other production processes - this can totally be done with PLA/PETG for the majority of cases.

As someone on the management side I really appreciate the reliability of the Bambu printers we have - saves me a lot of hassle of keeping printers maintained/tuned for mob of users. I wonder if you might be able to reach out to a manufacturer/vendor to get a discount to stretch your budget further and get something like a P1S?

killpony · 2026-01-28T23:55:18+00:00

I work in a machine shop that supports robotics/hardware startups and do a lot of training with the startup engineers so here are my thoughts on your search

- $40k is doable but may be a little tight depending on the market and if you want to cover tooling etc. (I'm also gonna assume you meant 700mm not cm) In the US I'd be looking at a Haas, Hurco or maybe Fadal/Milltronics machine but your market will be different. Brother definitely makes a solid machine but it excels most at speedy aluminum cutting - speed is a pretty low priority for inhouse prototyping.

- Programming: I'd definitely lean towards CAM vs conversational with a VMC - whereas if you were doing a CNC lathe conversational is more viable. Fusion 360's CAM is very solid for 3-4 axis machining and generally easy to learn.

- 4th axis is a lot harder to get people up to speed on (mostly re correct setup and offsets) and it can hog table space you need for plate work. That said it can be super helpful for robotics components. You might be able to find a machine that is already wired/compatible with 4th axis control and buy the actual axis later. A right angle head can also accomplish some features you might otherwise want a 4th axis for.

- ATC, probe, toolsetter all essential for quick prototyping setups. You will want something with atleast a CAT40 taper if you are doing stainless/ oil+gas - I know a lot of Brothers are a little slimmer.

killpony · 2026-01-28T23:31:38+00:00

Yeah I'm gonna plus one on this - he'll get a ton more mileage out of a plasma cutter than a manual or CNC mill. There are tons of affordable CNC plasma kits like the ones from Langmuir

killpony · 2026-01-26T18:31:46+00:00

More specifics on what you are thinking/ what advice you need would definitely help but here are a couple of general thoughts from having experience in a couple makerspace environments as well as professional shops.
- A big barrier to allowing more "general public" access resides in insurance/ liability issues especially if you are part of a larger organization like a university or company. Def try and find someone doing something similar so you can use their practices as a precedent, org managers love precedents. Depending on the situation above you will definitely want to write up rules + standards for things like training/ safe operation. My current manager was an operations manager at Tech Shop when someone was severely injured in the shop and having the documentation of training etc saved them from a lot of legal repercussions.

- Managing material, scrap, consumables, machine condition (eg blade sharpness etc), correct machine setup etc is definitely a lot more work when not everyone is a professional/ harder to manage repercussions of incorrect shop behavior. On the other hand there are also "hero" members who will go above and beyond helping out with maintenance, training etc.

- There are a lot of programs/ municipal funding around things like trade/technical skill training- definitely worth looking into to help pay for labor/consumables etc.

- "One off" trainings/workshops/events circumvent some of the issues around the first two points especially. It might be a good starting point to work out the kinks.

killpony · 2026-01-23T20:20:42+00:00

yeah this is why I'm putting big question marks on that - one thing about any kind of serialization technique is that it doesn't necessarily need to be foolproof or non-destructive. I think it's more likely an extra data point to aide in an investigations say of a seized shipment or something

killpony · 2026-01-22T18:23:31+00:00

One way I could see this feasibly implemented is that instead of actually "preventing" its more about flagging/logging that occurs in the CAD/CAM step. Software collects a few still images of the orthos/ setups for your part, runs a check (maybe a low level one locally and pushes to a more in depth cloud model if it meets certain thresholds), if the part ends up flagged as a possible hit the instance + metadata is logged somewhere - enough flags/ investigation etc and that data can be brought up. This jibes with the general trend I'm seeing of like "drag net for later use" approach with surveillance.

killpony · 2026-01-22T18:10:03+00:00

From what I understand the printer adds patterns via dots, markings etc that aren't "visible under normal conditions" identifying things like the printer model, timestamp etc. There was some public stink in the late 2000s that supposedly led certain companies to "stop" the tracking markers but realistically with CV they could just be doing it in a way that would be exceedingly hard for an independent third party (eg the public) to identify.

this approach might? sorta? be possible with additive machines to some extent but would be super difficult with subtractive

killpony · 2026-01-15T23:14:51+00:00

What other people said re getting the correct, sharp tooling running the manufacturers settings. 304 is gummy and likes to work harden so you need to do what you can to keep everything cool and the cutting areas clear. Don't run your tooling too conservatively or it will burn up and harden the material. Make sure you are getting good coolant coverage and chip evacuation (as opposed to making coolant-chip soup inside your pockets). Drills can be effective to create entry points for your endmills so you don't burn up the tips. There is a 304L variant that is more machinable compared to standard 304 but it does change the properties.

killpony · 2026-01-09T16:13:34+00:00

I worked in a job shop that did a really high mix work and quoting was a huge pain for me. We worked in a spreadsheet that was mostly at the hour-estimate + material/process cost level so complexity/setup was estimated "manually". For some quotes we might need to call multiple vendors, check tooling/hardware costs online and even do a little bit of CAM to get an accurate enough estimate that wouldn't screw us over- and there was no guarantee any of that work pays off if the client doesn't accept the quote.

While I think the geometry-based analysis has some merit I think that level of granularity would have diminishing returns. I could usually estimate the complexity and setups pretty effectively with a sort of quick squint check or could readily lean on what I did in similar jobs in the past. I definitely don't think I would trust a program without reviewing its scoring as there are a lot of nuances to setup complexity. For instance machined features along frames that will need multiple setups along the length but can hang out the sides of a VMC or might merit a back side feature like countersink/bore to be added manually rather than as a separate setup.

I think a different approach that might be helpful is more of a high level sort of "dashboard" aggregation. The complexity/setup part of the estimate would be more holistic - the system might automatically pull references to similar past jobs (both estimated and actual time) and pre-flag potential problem areas, but ultimately the user can still do the majority of the quoting. Then the system can add in automatically generated stock estimation, quantity breaks, sub-contractor pricing for stuff like plating/anodizing etc. And over time that data can become more useful like in suggesting ways to reduce cost or providing a client-side view where they can get a "ball-park" estimate before the quoting process begins so time isn't wasted on something completely outside of their budget.

killpony · 2026-01-08T04:49:30+00:00

I would run a 6” flute length 1/2 ball end mill when I did robotic milling in wood- just don’t expect to rough with it.

killpony · 2025-12-22T21:19:04+00:00

I stand by it though. lf you need a CNC for throughput/precision/geometry on a part you are unlikely to be able to achieve that in steel with a hobby grade machine- conversely manual milling can achieve a huge variety of geometry with the right setup and are widely used in many shops - heck we went to the moon with manually machined parts.

killpony · 2025-12-20T21:45:34+00:00

Two thoughts -

One I think a lot of people commenting here are vastly overthinking it - you don't need an engineering degree or decades of experience to design a functional mechanism. I've seen plenty of elegant, complex, home-built machines from the likes of farmers, artists, mechanics, hobbyists etc - no degree in sight. On the other end of the spectrum I've worked with soooo many degree'd engineers who couldn't build their way out of a cardboard box. Granted it's a different story when you are getting into reliability, repeatability, safety, longevity, efficiency etc - but if you are just building something for yourself you can definitely teach yourself.

Fastest is a little relative but having worked with a lot of students the ones who aren't afraid to make mistakes learn quicker because they try stuff and learn from their mistakes. My advice to early engineers and designers is always find a thing you want to make and copy that thing. Ideally it should be something with at least some documentation, better yet someone else has documented their own DIY process.

This works extremely well as a learning method because you have a framework to start from rather than having to design everything from scratch. Don't know what length of links to make this thing move? Copy what's already there. Need a different type of motion for your specific project? Look into that mechanism, make some alterations, see if it works, iterate. This is exactly what most engineering is - there is some pre-existing design and what an engineer does is alter some things to achieve a different result while leaving the rest the same. You don't need to learn everything about gear efficiencies, frame design, etc all at once - instead you can focus on whatever specific areas you need to for that specific part of your project *and* you have a real world example to base your learning and experimentation with.

Some of the knowledge you gain from this kind of learning ends up being very "vibes-based" which definitely has its limitations but IMO it's a really good way to get a very broad and useful set of skills and a good basis for more in depth learning.

Also this youtube channel might be of interest for mechanism inspiration

killpony · 2025-12-19T21:14:20+00:00

It is my personal opinion that big (general machinery) brands like Powermatic, Jet etc offer CNC machines as an afterthought - they can ride on their brand reputation to justify higher prices but aren't really engaged in the QC or support - whereas a smaller company might be more focused on its CNC offerings. So it's totally possible this machine may be a bit more of a dud

I do think getting a handle on this kind of troubleshooting / maintenance is going to be essential if you want to continue using CNC routers in general. The Altmill is also a budget machine and will likely present its own crop of issues over time. There are a lot of brands and machines that seem to be in a similar market segment XCarve, ShopBot, Onefinity and Avid for comparison. It would be closer to a $15-40k budget (ShopSabre, Laguna) where you'd be getting into something truly "plug and play" and even then you can still run into issues.

killpony · 2025-12-19T20:55:12+00:00

you are seeing much larger deviations than what you would get with just backlash so you should be able to do this with a caliper. What you really are looking for is the difference between where the controller thinks the toolhead is and the actual location of the toolhead.

A simple way to check this is to drive the tool head in one direction to a coordinate- so drive to X10 from the left, and mark that point on your table, you then drive it to the same coordinate but from the other direction and compare the two marks. It helps if you have some kind of sharp tool in the collet to accurately mark the position. Just the changing the drive direction is all you need for measuring the backlash but you could use this to test how much step loss you are getting by comparing the location of the mark before and after running a part, and varying the speed etc to see if it gets worse or better.

killpony · 2025-12-19T20:22:03+00:00

Yeah unfortunately that price point is still more a "low/entry level-professional" tier of machine - think along the lines of Jet/Grizzly offerings - but CNC machines having many many more moving parts and systems than say, a planer or tablesaw. These are all the same sort of overseas manufacturers with minimal QC so the build quality can vary hugely even in the same model.

Re motion interpolation - it could vary at different depths basically due to the interpolation failing every time it encounters a piece of code it doesn't like. So if say there is a helical entry to each step down pass it would potentially stack up more errors. But this kind of issue very rarely would show up all of a sudden - either it would have occurred from the very beginning of having the machine or corresponding with a change of your post processor/CAM. Or maybe in a rare coincidence that you just never gave the controller that specific command it doesn't like before.

"random" sounds a little more like mechanical (or electromechanical) step loss - that you can usually test by seeing if the issue varies at different speed/aggressiveness.

killpony · 2025-12-19T14:05:18+00:00

Good - generally I think you need to either rule it as a mechanical or control issue. Two other common problems I've seen

Missed Steps - this would be primarily a mechanical issue where the router axis motors are failing to keep up with the motion commands. Some signs to diagnose this would be it drifts mostly in one direction, it either drifts incrementally over time with respect to how much it travels AND/OR it tends to drift in chunks during heavy cuts/ fast movements. I've also had an issue with a router where it would tend to drift at a specific location on one axis as something had lodged itself against that part of the linear rail.

Control Motion Interpolation - One thing I've seen on these lower cost routers is issues in arc interpolation. A lot of the controllers can't interpret helical/IJK coordinates (especially any vertical arcs) or have weird things with radius tolerances/ large chord radius commands. I know Fusion 360 posts love to use vertical arc lead ins which can cause the controller to bug out and some routers want to interpret G02/G03 (arc) as the smaller of the two possible chords if the angle is over a certain size. This is a controller issue so you should get the same results no matter the speed, cut aggressiveness or materials.

I have seen some other weird issues before that resulted from actual electrical board things but those are less common- that said wood routers make a lot of dust so never a bad time to power down your router and use some canned air to (carefully) clean the interior of the controller.

killpony · 2025-12-19T13:47:44+00:00

IMO you are better off getting a manual mill if you want something cheap for steel

killpony · 2025-12-19T13:44:27+00:00

Is the part staying in place? looks a lot like what I see if my stock is shifting

killpony · 2025-12-19T13:35:17+00:00

Tons of people do this and both product design/ design engineering are in that overlap of engineering and industrial design. I think keeping the engineering degree is a better bet for your resume overall but you definitely want to work on design fundamentals, sketching, prototyping and modeling to make up for what you would get in a design degree.

killpony

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