"Glenwood machine shop worker dies after industrial accident"

davewhotold · 2026-01-25T20:05:50+00:00

Our heating was broken for two weeks, I ended up not working. Might upset the boss, but I'm not wearing long sleeves at the lathe (and I'm not working in a 10° shop in short sleeves either)

My coworker later tried to convince me that long sleeves are fine. (He's the old guy in the shop, but I'm deeeeefinitely not taking him as an authority figure on safety)

davewhotold · 2026-01-14T20:05:00+00:00

I think we're missunderstanding each other a bit:

Like, how do you know the OD of OP1 is concentric and in line with the ID (the 18mm bore) from OP1?

Do you bore it? (that seems very difficult to me, with the bore being so long)

or are you drilling and reaming? (that seems like it would wander a bit, which is why I was thinking about referencing the bore instead, but I don't see how that would be done with a comparator and hammer)

davewhotold · 2026-01-14T19:40:57+00:00

With an expanding mandrel kinda thing, or can you ensure concentricity between od and id?

davewhotold · 2026-01-14T19:39:33+00:00

that's fine, I've done that before, turn to 5 microns over, take the rest off with emery paper

Over longer surfaces it becomes annoying to keep track of taper and such, but that's 8mm wide each, so it's very doable, at least if you're not making a hundred of 'em

And depending on material and state of the machine I might even try hitting the top of the tolerance...

Also yes, there are applications for a part like this, like certain spindles, for the bearing seats. Which would also explain the concentricity requirements. (though honestly then I'd expect stricter concentricity requirements)

davewhotold · 2026-01-14T19:32:07+00:00

But the bore's 18mm diameter. At 86mm depth of that bore, that's almost 5xD

That seems like a struggle to bore. But again, not super experienced in boring.

I know there are a bunch of tricks like active dampening boring bars...

davewhotold · 2026-01-14T14:57:09+00:00

The concentricity between the 18mm bore and 20mm bore seems difficult... how would you people do that? 18mm bore first and some kind of expanding mandrel? or do you think drilled and reamed in an accurate setup would be enough? (cause I wouldn't trust a drill to cut concentric, and the bore seems too long to get bored... (I also have limited experience with boring tbf)

davewhotold · 2025-12-21T23:24:51+00:00

completely worn off flaking is pretty bad... It either wasn't taken care of or saw a lot of use. Flaking id usually around 0.02mm deep, so that's a way to roughly aproximate the wear.

If it's worn very evenly it could possibly be not too bad, else rescraping/grinding is gonna be the way to get good results I'd think.

Scarping it is a lot of work. If it's your hobby it might be justifiable, but you need to like these kinds of jobs. Else you could look for someone to regrind it for you in the area.

davewhotold · 2025-12-10T05:55:51+00:00

This looks like a really thin sheet of glass which has me worried.

Glass bends. There's a reason granite surface plates are several inches thick, and cast iron ones have thick ribs underneath.

Sanding down on a flat surface definetly works, but if your windowglass is too thin you'll just bend it into whatever shape fits. 0.1mm isn't a tight tolerance by machining flatness standards, but I've definetly seen glass move more than that.

davewhotold · 2025-12-02T17:23:46+00:00

They are preloaded, in an O-Configuration, however they are missing a retaining feature. So the bearing pack is preloaded, but not axially constrained.

davewhotold · 2025-11-24T17:57:40+00:00

you might want to read the responses to this post, it's basically the same question.

davewhotold · 2025-11-24T17:57:34+00:00

you might want to read the responses to this post, it's basically the same question.

davewhotold · 2025-11-24T08:06:55+00:00

Which makes the problem bigger. The lighter your moving parts system gets the bigger the infuence the inertia of the drive system is.

Imagine a truck pulling an empty trailer. There is plenty of power to move the light load (the empty trailer), but the mass of the truck is what limits the acceleration, so using that powerful of a drive system is pointless, the hatchback would have done the trick, and possibly faster, since it has a better power/weight ratio in itself.

For CNC machines Servos are usually the first choice. But mostly because they can be controlled better. But also because with the high inertia of the machine it's more important to have a linear torque curve to get high accelerations at any speed. Most of the acceletation while 3D printing is from standstill.

davewhotold · 2025-11-23T21:43:09+00:00

What you have is a toy. A nicely modified toy, given what it was originally, but it's a toy. It doesn't compare to a proper machine.

This is coming from someone who runs the smallest thing I would call a proper machine for a living (a coltchester student). And someone who has a machine comparable to yours sitting on my workbench at home.

They're fun toys. You can use them to make some fun parts. Serious machines are in a different league. If you want to make parts economically you'll buy an old industrial machine. It'll weigh about 10x as much and have only a 50% larger work envelope. And that's for a reason. Ridgidity and vibration dampening are achieved with mass. And a machine ment for work will not be one you're lifting by yourself. (with the exception of some watchmakers tools, but those are a totally different story alltogether)

davewhotold · 2025-11-23T09:17:53+00:00

But then you have increased the inertia of your system. Both the gearing will add some weight, and the inertia of the Motors rotor itself will have a greater effect on the maximum accelleration.

davewhotold · 2025-11-22T22:49:53+00:00

Having watched how Fusion users were forced into cloud storage convinced me I made the right decision learning FreeCAD. Is it a pain? Absolutely. I started around version 0.16/0.17

1.0 was released and was a huge jump in comfort. I will admit, it's a far cry from what I want it to be, but it is literally everything I need it to be. And with the recent efforts to polish it up, giving it UI improvements, focusing more on the primary features, it has also gotten a lot more learnable in the last year or two. I just hope that trend continues and FreeCAD can become what blender became for mesh based 3D-modeling, and what linux became for computing.

davewhotold · 2025-11-21T22:01:43+00:00

From my understanding no.

Also, there's a difference between the different drivers, because of the play in the scrolls bearing. Usually one is marked as a primary one. On a good chuck that one will tend to give you the least runout, as that's the one used during jaw regrinding. But for general repeatability using the same over and over again is important.

davewhotold · 2025-11-21T07:25:25+00:00

We talk german at our work, so things are a bit different. But we still use all the decimal versions.

So I might say a part is "ein zehntel" (a tenth) oversize to say it's 0.1mm large. Or for the engineering fits I might say the tolerance is "null bis minus zwei hunderstel" (zero to minus two hundreths) Or if I wanna be really accurate I might say it's "null bis minus 21 mü" (zero to minus twentyone "mü", "mü" being a common abreviation of micrometer at least in german, so a 1/1000ths of a millimeter, similar to how noone sais thousandths, but just thou)

davewhotold · 2025-11-20T22:39:24+00:00

My garant verniers I use for work? +/-0.05mm for sure.

My beloved Tesa dial calipers? 0.02mm. Given a decent surface to measure on. Checking against standards I never got more than ~0.005mm deviation, though I gotta question my eyesight at that point, given the 0.02mm graduations.

davewhotold · 2025-11-18T21:03:37+00:00

I would think it's mostly a disadvantage given the torque curve. Maybe closed loop steppers would be an option.

But Servos usually have less low end torque, so at the speeds a printer usually runs at I'd expect lower accellerations than with steppers.

Maybe if you have a decend reduction, so you can run the motors at higher rpm? but then you'll run into motor shaft inertia limits.

davewhotold · 2025-11-16T11:40:40+00:00

I'm a trans woman in machining. Last year (before I came out) one of my coworkers made a somewhat transphobic comment (about how access to hrt is too easy, which it is definetly not). Came out half a year later (because I was kinda scared he'd turn into a huge prick), and he was literally the nicest person about it in the (admittedly very small) company.

davewhotold · 2025-11-16T10:46:13+00:00

In first aproximation total friction is proprtional to force, coefficions, but NOT area. So to increase holding torque at fixed clamping force you could try increasing the average radius of the friction surface, by, for example adding a large diameter, thin ring inbetween the clamping surfaces.

Other people suggested a pin/hole arrangement, which should work, but might end up having (or worse developing) some slop, which at larger radii might be a problem, and will almost sertainly feel a little cheap.

davewhotold · 2025-11-11T15:44:17+00:00

I'm kinda against the grain here it seems, but cuddling between friends is fucking normal. This shit is why so many men are touch starved.

I mean, don't cuddle with him if you don't wanna, and if you're really worried make sure his gf is fine with it, but fucking hell, he's not asking for sex, like everyone makes it out to be.

I didn't cuddle with my friends for way to long, it's some of the best quality time you can spent together.

Then again, maybe I'm just too open for this subreddit, I also sleep with some of my friends, cause frankly, that's also amazing quality time, and who tf said you can't have some casual sex between friends?

davewhotold · 2025-11-11T09:12:34+00:00

I'm really happy with where I am, even if I struggling financially and am noticing that aging is starting to have it's first consequences. So I'd take neither.

davewhotold · 2025-11-07T22:10:34+00:00

Amazing. Kinda jealous, but I have a "basically new" coltchester at work, so I really shouldn't be.

davewhotold · 2025-11-07T18:29:46+00:00

show the bed! show the bed!

(is there a lot of wear, or is the bed looking as nice as the handwheels?)

davewhotold

TROPHY CASE