Sunday, May 16, 2021

machining acrylic

 short post about machining acrylic (PMMA, aka Plexiglas™, Perspex™, etc):

1. use sharp tooling
2. use soapy water for lube*

The result is an as-machined surface you can see through:

*make certain to clean and dry that crap off of your machine after each session,
since it will promptly rust your machine's most precious surfaces...

Friday, May 14, 2021


 I think I've mentioned both Dan Gelbart and Tim Hunchin in these pages.  

It occurs to me this morning that both will show you good ideas and both will teach important concepts.

 But Dan is coming at things from a "concepts taken to their logical conclusion" point of view.  Dan's way is how you do things when price is no object, and the goals alone define the scope - and limits - of your  work.

 Tim is coming at things from a "deadline is Thursday and the budget is five quid" point of view.  Tim's way is how you do things on a very low budget, in a hurry.

 They are polar opposites, really, and in my opinion, both viewpoints are worth studying.  In practice, you are likely to find yourself somewhere in the middle.  Probably.

Wednesday, May 12, 2021

CNC (Computerized Numerical Crashes)

 Whilst I recover from A) sciatica and B) having to return 50% of my recent purchases for the shop, please to be enjoying this video evidence of why I will never own a CNC machine...

 WARNING: if you are squeamish (about expensive mistakes - there's no blood here), the action in this video may be too intense for you- it certainly made me wince and cringe several times!

Tuesday, May 11, 2021

I cannot translate Chinese to English...

 ...but I can translate Chinglish to English, and it seems to me this is a needful service. <_<

 By the way, I am not pointing and laughing at anyone for having poor English skills, no, not ever, because I don't speak ANY other language - I would be a terrible hypocrite, and I am frequently disappointed in myself for not having picked up a second language.  So anyone who speaks a second language - even marginally - gets only respect from me.

 No, I am pointing and laughing at the business who paid someone to do localization, and got THIS in return:

About this item

  • ✅ Knife Sharpening Kit: the whetstone size 8.5 x 3.5 x 1.9 inch for whet stone set, the shipping weight is 2.5 lb. The premium quality knife sharpener stone set contains one dual side grit in 1000 and 6000, non-slip holder base with rubber gasket, angle guide, flattener stone, and a printed user guide.
  • ✅ Sharp Function: the best knife sharpening stone could sharping all kitchen knife knives, chefs' good choice. It have same functioning as the other kind chef sharpnerer, king whetstone, diamond sharpeners, cutlery kershaw sharper, steel knife sharpeners, piedra para afilar cuchillos wet stone, katanas, sword, arkansas, nagura naniwa, cerax onion, norton, strop, tycano system and other hand-made metal sharpeners.
  • ✅ Chef's good choice for kitchen knife. It is a good gift / gifts for men whom loves cooking. The whetstone sharpening set is also widely used for sharpening machete, whittling knife, hatchet, forged knive, throwing axe, plane, clipper, ruixin glass, ikon, afilador, cocina, lain, wicked and kamikoto shaperners speedy.
  • ✅ Best Holder for Sharpener Stone Kit. The stone is classified as wet stone, water stone, whetstone, whet stones, of which to be hold in the bamboo base holder, with non-slip rubber base, it make the sharpeners in a stable position and sharping the knives edge quickly. No honing oil is required.
  • ✅ Global Usage. The premium whetstone in good combination of 1000/6000 grit could sharpen all knife blade to make the knife use widely, the 1000 grit could remove the dull or damaged blade easily, let it flatten in line, the 6000 grit could remove the burr during sharpening and make it sharp!  
 "Sharpnerer."  By the way, using oil or water is nearly always a good idea, even with aluminum oxide manufactured stones like this, as the fluid helps keep the removed material suspended or even washed away, rather than collecting in the pores of the stone and slowing down material removal.

NOTE: I am _not_ an expert sharpnerer.  If you are, and you know differently from what I just wrote, please do @ me, the day I am unwilling to learn or admit that I'm wrong (in general, ahem) that day you can stick my in the ground.*

 So close, and yet, so far... seems to me they actually used more words than necessary, perhaps in an effort to be fancy... but it just comes across as word salad.

 I'm thinking they could probably have saved a few cents on the "printed user guide" as well, unless it's all pictures, Ikea-style, knowutimsayin'? @_@

 By the way, spoken Chinese may be one of the few spoken languages which is actually harder to learn than spoken English, possibly because of the five tones thing.  Mad props to anyone who can speak Chinese even half-assed.

*hey you know what's totally cool and completely unrelated to
this post?  It just became legal in this state (Colorado) to do "body
composting" which is to say, decomposing human remains naturally,
without a box, and then actively returning the fully decomposed
remains to the natural environment, or in some cases, even agriculture!
 That's for me, you fuckin' betcha. When my wife wakes up and I tell
her, she will literally be thrilled, it will literally make her day. 
I can't wait. I love doing shit like that. ;)

Ach, Digression #2:  And we must find ways to do that - make each
other's day - for each other, everywhere, y'all.  This world will grind
you into hate-paste if you don't fight back with love and art and
music and beauty; this is a moral imperative.
 Just thinking out loud, sorry.

Monday, May 10, 2021

in praise of an oily rag

Once upon a time, when steam engines were powering explosive economic growth and the men who operated such machines became one of the first blue-collar jobs to actually be considered honorable, despite the fact thaat most of them were filthy.  Part of this was due to a well-deserved fear of steam engines, since boilers were blowing up and killing people on a fairly regular basis, so the men who tamed and made safe such powerful engines "must be" accomplished or educated in some fashion.  The possibility that such men were merely mad as hatters was probably an unpalatable notion.

 Now these men were frequently seen holding an oily rag in one hand, and an oil can in the other.  This was because, in the early days of mechanization, sealed bearings had not yet been invented, so bearings required regular oiling to refresh their lubricant.  The oily rag was for wiping grime from polished surfaces, not for aesthetic reasons, but to keep sealing or bearing surfaces clean so that they wear out slower.

 In general, when working with heavy iron and steel machinery, one is always either on the lookout for, or doing direct battle with, rust.  We can't simply make all the machinery out of non-rusting steels for multiple reasons.  Cost is certainly a factor, but also cast iron has desirable properties which "stainless" alloys do not, and where hardened surfaces are required, stainless alloys simply are not suitable.  So every surface surrounding a turn-of-the-century engineer was something which could rust.  So if it wasn't painted, it had to be kept oily, not only to lubricate it, but to prevent rust.

 This is why the engineer or mechanic always seems to be wiping his hands on a dirty rag.  "Dirty" is relative, and quite often one finds oneself wiping something that should be kept oily.  One literally needs an oily rag 10X or maybe even 100X more often than a clean one.  Hell, I have been known to put oil on a clean rag for this reason.

 Although steam engines and their operating engineers went away, people who work with large machines still tend to keep an oily rag handy for the same reasons.  So machinists in a few small metal-working shops can still be seen with an oily rag in one hand, not only keeping their machine clean and watching its operation, but also listening to it attentively, since a slight change in sound can often predict a machine or part failure long before it happens.

 However, modern sophisticated machines with active lubrication systems and sealed or protected bearing surfaces are now being made from super-alloys which are both strong, hardenable, and rust-resistant.  And there are literally acoustic failure detection systems which can listen in place of the experienced machinist.

 Mean-Time-Between-Failure numbers - for good quality equipment - have gradually become enormous.

 And that means that slowly, the sight of the experienced old engineer / mechanic with the oily rag in one hand, is rapidly disappearing from this world.  Just another interesting change I have witnessed in my time so far.

Sunday, May 9, 2021

Jet Tools considered harmful

  I need to vent.  I've recently had a very hard lesson in the ancient warning, "buyer beware".  For literally decades, I've had my eye on a 3-in-1 sheet-metal-working machine.  Long ago I decided I would have to get something from Jet or Grizzly, because I thought it would be affordable enough to buy new so long as I bought SEIG*, and used an American dealer so I could get parts and service.

 A few weeks ago I did just that, and I pulled the trigger on a Jet 30" wide machine.  Unfortunately, when it arrived, the crate was broken.  I should have just refused the shipment, since the fuckers on the truck had tipped the whole thing onto its side, and it was still on its side in the back of the truck when they showed up.  

 Of course, it didn't help that the people who shipped the thing never thought to put any "UP" arrows or "THIS END UP" signs anywhere on the outside.

 But I told myself it was a big hunk of cast iron, and the box was only a little beat up, it was probably okay.  More fool me.

 Once I got the lid off the crate and started inspecting it, long after the truck had left, I found all kinds of heinous problems.

 For one thing thing, the shippers had only installed two bolts in the four holes of the base holding the machine to the skid.  When the shippers tipped it up on one end, the machine's 300+ pounds of weight was too much for the two skinny bolts they used; one snapped and the other bent severely and pulled its head half-way through four inches of plywood...

 The blades of the shear were the most fucked up of the whole thing.  They had been shimmed into place, despite the fact that they are supposedly equipped with two cutting edges so they are reversible... not these, not unless you took the bends out of them first. O_O

 The problems went on and on, and many of them were manufacturing / QC issues that had nothing to do with shipping.

 The good news is that I bought it through Amazon and the return should be no-hassle.  We'll see.

 I also ordered an abrasive blasting cabinet recently, and the seller kept my money for three weeks before I enquired whether I would get a tracking number, at which point I found out they had never shipped anything.  They gave me a sob story because they want to preserve their ratings, but IDGAF.  Actions have consequences.

 It turned out I can drive to a store here in town that has the same unit for considerably less money.  I just can't do it right now, because neither I nor wife can unload the thing from the vehicle once it's in there.  I might literally have to open the box and take the parts out one at a time because both the wife and I have weight lifting restrictions.  I can't lift more than twenty pounds at the moment.

 And so it goes.  I'm actually re-thinking the whole sheet-metal machine purchase entirely.  While I do want the capability, I don't like the compromise that the all-in-one machine felt like.  There are combo brake-and-shears with no roll that are a lot more sensible.  But then I'd probably spend the rest of my life wanting a slip roll and not buying one, because I would only need the thing every 18 months.  *sigh*

 I might find myself getting a plasma cutter & XY table, or a vertical band saw first, I dunno.  Need to replace welding gauges too and blah blah a hundred other tools, upgrades, and repairs.  I got a white-board full of 'em.

*for those unaware, most of the hardware and tools sold by Grizzly, Jet, MSC, and others
are made by one company in Shanghai

Saturday, May 1, 2021

Dan Gelbart on 'Prototyping'

 Come for the general prototyping advice, stay for the astonishing shop-made instruments and machines.

 Dan is just as comfortable bashing sheet metal with a hammer as he is with his all-air-bearing, all-granite-slides, micro-inch-capable, lathe-mill-drill CNC machine which he designed and built from scratch...


Oh FFS. 

 I ordered from this jackass specifically because it said 'FEDEX' because I have had endless infuriating problems - both apparent thefts and repeated misdeliveries - with USPS, so I carefully avoided USPS - or so I thought - by buying from this ass-clown.  Well more fool me.

 EDIT, much later: not too surprisingly, the seller issued me a refund after holding on to my money for three weeks and never shipping anything. Then they gave me a a very unprofessional song and dance about how their personal problems prevented them from effectively communicating with their "warehouse people" (if they have a warehouse, I am a Klingon) but really it was actually the warehouse people's fault and blah blah blah I have no more fucks to give.

 So then I figured out I could get it from the local Harbor Freight store for much less.  Forgive me father, for I have been an idiot.

Wednesday, April 28, 2021

dust separator or nuclear warhead? (lulz)



 The weight's on mine is a bit off though; a real W-80 weighs nearly 300 pounds - like the guy in the pink shirt.

caveat emptor 3,617 (re; blast cabinet)

 I stumbled over a gotcha with the soon-to-be blast cabinet that I thought I had better share.  I am changing the cabinet over from using a siphon gun with a trigger valve to using a siphon gun with a foot pedal.

  Without thinking about it too much, I picked up a likely-looking foot pedal air valve from eBay, like the one in the photo.  Note the cheap plastic "guard" mounted to the pedal (with some rinky-dink plastic spacers not visible in the photo, since the two parts clearly were not made for each other).

 It turns out that it doesn't flow much air, and when it comes to abrasive blasting, air flow is as important or more so than operating pressure.

 This valve is probably intended for the rubber modulator valves used with pressure pot blasters, for which it would be fine, as those modulators do not require flow, only the presence or absence of pressure.

 Now it turns out that there are high-flow air valves in foot-pedal form, but there don't seem to be very many, and they are all based off the same valve, just with different sheet metal and paint surrounding it.  And annoyingly, there is only one that is reasonably affordable... and it's out of stock at the vendor right now. O_O

 There is, however, another way to accomplish the same thing: a fairly affordable ($20 - $30 for CN-sourced) solenoid valve having sufficient Cv (flow capability) and a relatively affordable (in my case, I think I already have one) electrical foot switch to operate it.

 More on this as things develop.  Right now, I've got a pile of accessories and upgrades for a sandblasting cabinet which hasn't arrived yet.

 EDIT, LATER: now the vendor is trying to avoid accepting a return.  Item was sold with terms including "Free 30 Day Return".  They asked me for a fookin' video explaining why it isn't suitable...

 This awful seller is 'brandz4all' and I am throwing these jerks under the bus now, because they are trying to avoid having a return and they want to stretch the correspondence out for 30 days after which their small amount of liability for the sale evaporates. GRRR... the thing is, that account is just one of many, many accounts held by one person, who is selling the stuff through an internet cafe's computer - in China - and the stock isn't anywhere near them, it might be in China somewhere, or it might be on a container bound for the USA, or it might be on the CONUS somewhere already, and some random cottage industry freight forwarder, in this case, allegedly someone in Franklin Square, New York.