On Tue, 25 Jan 2022 23:24:34 -0700, Don Y <blockedofcourse@foo.invalid> wrote:>I need a screw (a bit over 1/4" thread diameter) with a hole >drilled longitudinally throughout its length. The hole as >large as feasible without significantly reducing the strength >to unusable (nebulous term) levels. > >I realize I will eventually have to contract a casting or machined >parts. > >But, am looking for onesy-twosy quantities to demo a prototype. > >I thought I could approximate it using a threaded tube (NOT >a pipe nipple). But, getting premade threaded tubing in that >range seems difficult. > >I thought of manually threading a (soft, brass?) pipe of >suitable ID/OD. > >Also thought of having one *printed* -- but I'm not sure getting >the threads right would be practical (driven by how fine the >layers are?). (I think most *plastics* would be too brittle >when torqued in such an application so I'd have to print in >metal) > >I also thought of physically removing the core material from >a COTS screw (drill/cut -- possible with a brass screw?). > >Any other options?Many. But you need to define what you are trying to accomplish here, versus all the things that didn't work, or useful answers may be rare. What metals are allowed or required? The quickest solution may be to use a metalworking lathe to make the needed bit. Unless the following works: .<https://www.mcmaster.com/threaded-tubes/hollow-threaded-studs/> Joe Gwinn
"Hollow" screw
Started by ●January 26, 2022
Reply by ●January 26, 20222022-01-26
Reply by ●January 26, 20222022-01-26
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> Wrote in message:r> Don Y wrote:> I need a screw (a bit over 1/4" thread diameter) with a hole> drilled longitudinally throughout its length. The hole as> large as feasible without significantly reducing the strength> to unusable (nebulous term) levels.> > I realize I will eventually have to contract a casting or machined> parts.> > But, am looking for onesy-twosy quantities to demo a prototype.> > I thought I could approximate it using a threaded tube (NOT> a pipe nipple). But, getting premade threaded tubing in that> range seems difficult.> > I thought of manually threading a (soft, brass?) pipe of> suitable ID/OD.> > Also thought of having one *printed* -- but I'm not sure getting> the threads right would be practical (driven by how fine the> layers are?). (I think most *plastics* would be too brittle> when torqued in such an application so I'd have to print in> metal)> > I also thought of physically removing the core material from> a COTS screw (drill/cut -- possible with a brass screw?).> > Any other options?You could always just cut a slot in the screw with a Dremel.If you need something better than that, you can get "vented screws" from Mcmaster Carr.CheersPhil Hobbs-- Dr Philip C D HobbsPrincipal ConsultantElectroOptical Innovations LLC / Hobbs ElectroOpticsOptics, Electro-optics, Photonics, Analog ElectronicsBriarcliff Manor NY 10510http://electrooptical.nethttp://hobbs-eo.com+1 Lots of options there... https://www.mcmaster.com/vented-screws/ -- ----Android NewsGroup Reader---- https://piaohong.s3-us-west-2.amazonaws.com/usenet/index.html
Reply by ●January 26, 20222022-01-26
Clive Arthur <clive@nowaytoday.co.uk> wrote in news:ssrlsb$4kq$1@dont- email.me:> On 26/01/2022 06:24, Don Y wrote: >> I need a screw (a bit over 1/4" thread diameter) with a hole >> drilled longitudinally throughout its length. The hole as >> large as feasible without significantly reducing the strength >> to unusable (nebulous term) levels. > > <snip> > > 'Hollow screw' is a good search term. >'Hollow threaded rod' is what I hunted under. A thick walled pipe seems to be the right way to go. Find a machine shop that can roll the threads instead of cutting them. One could also thread one end and the other end only in the areas needing threads.
Reply by ●January 26, 20222022-01-26
On Wednesday, January 26, 2022 at 1:15:41 PM UTC-4, Joe Gwinn wrote:> Many. But you need to define what you are trying to accomplish here, > versus all the things that didn't work, or useful answers may be rare. > What metals are allowed or required?Yeah, good luck on getting that sort of info. This is sed where people start vague and continue that way. -- Rick C. + Get 1,000 miles of free Supercharging + Tesla referral code - https://ts.la/richard11209
Reply by ●January 26, 20222022-01-26
onsdag den 26. januar 2022 kl. 21.05.07 UTC+1 skrev gnuarm.del...@gmail.com:> On Wednesday, January 26, 2022 at 1:15:41 PM UTC-4, Joe Gwinn wrote: > > Many. But you need to define what you are trying to accomplish here, > > versus all the things that didn't work, or useful answers may be rare. > > What metals are allowed or required? > Yeah, good luck on getting that sort of info. This is sed where people start vague and continue that way.seems a recurring pattern with Dons threads, he asks for something and every suggesting gets dismissed with a wall of text with more and more obscure additional requirements and reasons why it won't work
Reply by ●January 26, 20222022-01-26
On Wednesday, January 26, 2022 at 5:11:10 AM UTC-7, Don Y wrote:> On 1/26/2022 3:35 AM, Dan Purgert wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA512 > > > > Don Y wrote: > >> On 1/26/2022 12:10 AM, Jasen Betts wrote: > >>> On 2022-01-26, Don Y <blocked...@foo.invalid> wrote: > >>>> I need a screw (a bit over 1/4" thread diameter) with a hole > >>>> drilled longitudinally throughout its length. The hole as > >>>> large as feasible without significantly reducing the strength > >>>> to unusable (nebulous term) levels. > >>> > >>> braze or solder a nut onto a threaded tube. > >> > >> It's finding the threaded tube (of the right ID/OD) that is > >> the challenge. > >> > >>> OTOH parts like this are used in lighting, mechanical, and plumbing > >>> applications, perhaps you can get what you want off the shelf. > >> > >> The first thought was that of lamp rod. But, while claiming to be a > >> nominal "1/8 inch" diameter, the actual dimensions across the threads > >> are ~3/8". Far too fat for my needs. > >> > >> <https://www.amazon.com/Lamp-All-Thread-Pipe-Steel/dp/B008UWATVK> > > > > Yeah, that's because that "1/8 IP" is an "Iron Pipe" (or I think > > nowadays "International Pipe") dimension that defined the nominal inner > > diameter, not the outer. Note that a quick google indicates the actual > > ID is over a 1/4" on the rod you linked (way to go, 19th century naming > > conventions!) > Exactly. > > Ever notice how *pots* (as in "flora") are sized? Or, other "dry measures"? > > https://www.sizes.com/materials/pipe_Briggs.htm > > > > As far as I am aware, all pipe is still sold based on the (nominal) > > inner diameter, not the outer. Least this remnant of "half inch" copper > > pipe I have to hand is 0.625 (5/8) OD... > But the outer diameter is the *controlled* dimension! The inner diameter > is a consequence of the pipe schedule. So, all "1/8" pipe has the same OD > (0.405) but differing IDs depending on wall thickness -- 0.035 to 0.095, > in this case... a pretty big range! In my case, I'd prefer the OD to > shrink based on schedule and hold ID constant. > > E.g., if the ID was *actually* 0.125 and I could use the thinnest wall > pipe, I'd be in the 0.195 range for OD... Up to 0.315 with the thickest > (which would be a tolerable ~5/16" instead of a fat ~3/8+) > > Or, specify the size based on the OD and let the ID vary. > > The current scheme is the worst of all worlds...Would 1/4-28 (or even M6) tubing nuts work? I use them at work, they are hollow. Examples: https://kinesis-usa.com/gripper-fitting-nuts-1-16-od-tubing-1-4-28-flat-bottom-blue-002106.html https://www.coleparmer.com/p/idex-super-flangeless-nuts-1-4-28-flat-bottom-for-1-32-or-1-16-od-tubing/72807
Reply by ●January 26, 20222022-01-26
On 1/26/2022 7:47 AM, Dan Purgert wrote:> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > Don Y wrote: >> On 1/26/2022 3:35 AM, Dan Purgert wrote: >>> [...] >>> As far as I am aware, all pipe is still sold based on the (nominal) >>> inner diameter, not the outer. Least this remnant of "half inch" copper >>> pipe I have to hand is 0.625 (5/8) OD... >> >> But the outer diameter is the *controlled* dimension! The inner diameter >> is a consequence of the pipe schedule. So, all "1/8" pipe has the same OD >> (0.405) but differing IDs depending on wall thickness -- 0.035 to 0.095, >> in this case... a pretty big range! In my case, I'd prefer the OD to >> shrink based on schedule and hold ID constant. > > Yeah, I'm just good enough with pipes to know "I need $size ID", and notAnd, with pipe, you tend to be wanting to "fit" with existing pipe/fittings so your choices are inherently constrained.> really follow specifics past price at that point -- at least here, the > thin copper ("Type M"?) is allowed in residential plumbing, so it's > somewhat my go-to for repairs / rework. > > Although I do prefer the Type L in the kitchen and bathroom walls > (they're exterior walls, so the thicker pipe makes me feel better, even > if it is daft).We use K & L, here. The hard water "eats" pipe (lots of pinholes). So, spend the time/money up front instead of having to do it over, later.
Reply by ●January 26, 20222022-01-26
On 1/26/2022 9:48 AM, Dimiter_Popoff wrote:> On 1/26/2022 8:24, Don Y wrote: >> I need a screw (a bit over 1/4" thread diameter) with a hole >> drilled longitudinally throughout its length. The hole as >> large as feasible without significantly reducing the strength >> to unusable (nebulous term) levels. >> >> I realize I will eventually have to contract a casting or machined >> parts. >> >> But, am looking for onesy-twosy quantities to demo a prototype. >> >> I thought I could approximate it using a threaded tube (NOT >> a pipe nipple). But, getting premade threaded tubing in that >> range seems difficult. >> >> I thought of manually threading a (soft, brass?) pipe of >> suitable ID/OD. >> >> Also thought of having one *printed* -- but I'm not sure getting >> the threads right would be practical (driven by how fine the >> layers are?). (I think most *plastics* would be too brittle >> when torqued in such an application so I'd have to print in >> metal) >> >> I also thought of physically removing the core material from >> a COTS screw (drill/cut -- possible with a brass screw?). >> >> Any other options? > > How long do you need it to be? If within reason (< say 50mm) > and if you were living in the neighbourhood I could have made it > for you... Well not 1/4", M6 but I suppose you'll live with that. > A 4mm hole would be OK I think. I have some supply of 8mm brass...None of my neighbors have a lathe -- too many "professionals" who pay folks to do things instead of doing for themselves (no one works on their own cars, does their own plumbing/electrical, maintains their own yard, etc. If it snowed, here, they'd hire folks to clear their driveways!) I can use a lathe at the local maker house. But, that's half a day of my time -- long drive into town, getting time on a lathe, checking work (so I don't have to make a return trip) then back home. And, covid has frequently shut them down, so... [Hence the appeal of using a drill press; I can get to one of those in short order! And, I could *test* (strength) different hole diameters (wall thicknesses) to see where the integrity of the fastener starts to suffer, incrementally and interactively. That flexibility isn't likely available in a COTS solution: "Can I get this with a slightly larger hole diameter?"] I chatted with an ME friend, today. His first comment was to ask how I was going to do this in production -- how much I was willing to pay (time/labor) for the functionality that this provides. "Oh." "A screw is a stupid idea. Too pedestrian! Too many manufacturing steps -- for the screw itself and your use of it!" Then, took me back through a discussion we'd had years ago when I'd shown him some prototypes of hand tools I'd designed and the resulting *manufactured* products... how my "made in basement" approaches had been translated into "making hundreds per hour". (it's been a long time since I've been in a factory!) Kinda like showing someone "outside the industry" stencil-and-paste who'd always thought in terms of "soldering irons". It's not just a matter of time/labor saving but also a different set of possibilities! So, I'm revisiting the mechanical design with an eye towards driving the manufacturing costs to zero (consumer quantities so I don't have much margin to waste). And, seeing what other functionality I can add at the same time! :>
Reply by ●January 26, 20222022-01-26
On Tuesday, January 25, 2022 at 10:24:58 PM UTC-8, Don Y wrote:> I need a screw (a bit over 1/4" thread diameter) with a hole > drilled longitudinally throughout its length... > I thought I could approximate it using a threaded tube (NOT > a pipe nipple). But, getting premade threaded tubing in that > range seems difficult.If it takes real strength, you'll want to center a mass-produced steel item for end-on facing, spotting, and drilling; a mill or lathe would be the best tool for that. Machine screws are usually rolled thread nowadays, that's an operation that isn't compatible with hole-in-the-middle tube. Allthread rod is standard and cheap, allthread tube is not. Can you substitute a rivet with a hole in the middle? Those can be formed from tube in a variety of sizes and materials...
Reply by ●January 26, 20222022-01-26
On 1/26/2022 6:16 PM, whit3rd wrote:> On Tuesday, January 25, 2022 at 10:24:58 PM UTC-8, Don Y wrote: >> I need a screw (a bit over 1/4" thread diameter) with a hole drilled >> longitudinally throughout its length... I thought I could approximate it >> using a threaded tube (NOT a pipe nipple). But, getting premade threaded >> tubing in that range seems difficult. > > If it takes real strength, you'll want to center a mass-produced steel item > for end-on facing, spotting, and drilling; a mill or lathe would be the > best tool for that. Machine screws are usually rolled thread nowadays, > that's an operation that isn't compatible with hole-in-the-middle tube. > Allthread rod is standard and cheap, allthread tube is not.Screws "invite" twisting. So, in addition to tensile strength, you have to worry about deformation from twisting. And, even if you use "security" hardware, the user will sense that this is the "fastener of interest" for his attentions.> Can you substitute a rivet with a hole in the middle? Those can be formed > from tube in a variety of sizes and materials...Yeah, that was my thought (elsewhere, this thread, in the context of "spring clips"). The threads increase the diameter just to provide the fastening ability. If, instead, you can use a smooth outer surface, then you can opt for a smaller overall diameter *or* a larger internal bore. Hollow rivets are COTS in a variety of sizes/lengths. And, tend to *discourage* attempts at disassembly (short of drilling them out... but, someone undertaking such an action knows that they are destroying the product, not just "taking it apart -- for later reassembly!") But, if one end of the rivet remains "blind", you need something to grab it/bite into it. This then makes disassembly difficult when you *want* to disassemble the item! I ran the question by a friend, earlier today. He's promised to drop some photocopies (of fastener options) in the mail to me (yeah, he's real "old school"). Meanwhile, he's got me started rethinking all of those assumptions (why a screw? why round? why a round hole? why *centered*? why...) esp those that I've self-imposed by trying to DIY a prototype!
