\"Hollow\" screw...

[Joe Gwinn]

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

 

[Martin Rid]

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 Hobbs
Principal 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/
--


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[server]

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.

 

[Rick C]

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

 

[Lasse Langwadt Christensen]

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

 

[DemonicTubes]

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:
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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

 

[Don Y]

On 1/26/2022 7:47 AM, Dan Purgert wrote:

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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 not

And, 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.

 

[Don Y]

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! :>

 

[whit3rd]

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...

 

[Don Y]

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!

 

[whit3rd]

On Wednesday, January 26, 2022 at 7:01:04 PM UTC-8, Don Y wrote:

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...

Can you substitute a rivet with a hole in the middle? Those can be formed
from tube in a variety of sizes and materials...

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!

Howabout drive rivets? The drive pin in the head expands the rivet\'s nether
region, but could also be driven through and leave a hole, or with an overlength pin,
could be driven and retracted... or even drive a hollow pin (perhaps with
a driver that fills the hollow, for strength).

 

[Don Y]

On 1/26/2022 8:54 PM, whit3rd wrote:

On Wednesday, January 26, 2022 at 7:01:04 PM UTC-8, Don Y wrote:
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...

Can you substitute a rivet with a hole in the middle? Those can be formed
from tube in a variety of sizes and materials...

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!

Howabout drive rivets?

\"Pop\" rivets?

The drive pin in the head expands the rivet\'s nether
region, but could also be driven through and leave a hole, or with an overlength pin,
could be driven and retracted... or even drive a hollow pin (perhaps with
a driver that fills the hollow, for strength).

I think the tool is intentionally designed to snap the drive pin off below the
lip of the rivet, regardless of how long the pin *was*. I\'m not
sure if interposing a mechanical spacer between the tool and the lip of
the rivet would result in the break point moving to remain close to the tool...
or the rivet\'s lip!

Driving the broken off part of the pin further in (to clear the hole)
isn\'t always possible; there\'s \"stuff\" on the other side with which it
would interfere.

But, \"bare\" rivets -- chosen for length and secured \"otherwise\" may
work.

There are similar shaped COTS pieces that might also show promise

<https://www.placediverter.com/wp-content/uploads/place_diverter_compression_fittings-1a.jpg>
save for length (I\'m trying to see how much shorter I can make
these with a packaging rethink)

The key revelation is not to think in terms of \"screws\" as
that constrains your solution space unnecessarily!

 

[whit3rd]

On Wednesday, January 26, 2022 at 11:47:20 PM UTC-8, Don Y wrote:

On 1/26/2022 8:54 PM, whit3rd wrote:
On Wednesday, January 26, 2022 at 7:01:04 PM UTC-8, Don Y wrote:

But, if one end of the rivet remains \"blind\", you need something to
grab it/bite into it.

How about drive rivets?
\"Pop\" rivets?

No, not the apply-tension type, the apply-percussion type, that uses
a pin protruding from the head that is struck with a hammer...

<https://www.mcmaster.com/rivets/rivet-type~pin-drive/>

The drive pin in the head expands the rivet\'s nether
region, but could also be driven through and leave a hole, or with an overlength pin,
could be driven and retracted... or even drive a hollow pin (perhaps with
a driver that fills the hollow, for strength).

 

[Don Y]

On 1/27/2022 1:21 AM, whit3rd wrote:

On Wednesday, January 26, 2022 at 11:47:20 PM UTC-8, Don Y wrote:
On 1/26/2022 8:54 PM, whit3rd wrote:
On Wednesday, January 26, 2022 at 7:01:04 PM UTC-8, Don Y wrote:

But, if one end of the rivet remains \"blind\", you need something to
grab it/bite into it.

How about drive rivets?
\"Pop\" rivets?

No, not the apply-tension type, the apply-percussion type, that uses
a pin protruding from the head that is struck with a hammer...

But, presumably, the force required wouldn\'t *require* a hammer
as the pin\'s motion is deforming the rivet in a manner simmilar to
the \"early tugs\" on a pop rivet. The final -- higher force -- tug
on the pop rivet is solely to snap the pin; the rivet has already
been deformed (i.e., the pin could be left in place without affecting
the quality of the fastening).

Or, are the rivets made of tougher stuff that requires more force
(e.g., hammer-struck)?

I\'m off to hardware store, today, for some spray paint. I will see if
they have anything that I can evaluate.

Thanks!

https://www.mcmaster.com/rivets/rivet-type~pin-drive/

The drive pin in the head expands the rivet\'s nether
region, but could also be driven through and leave a hole, or with an overlength pin,
could be driven and retracted... or even drive a hollow pin (perhaps with
a driver that fills the hollow, for strength).

 

[Don Y]

On 1/26/2022 7:29 AM, Clive Arthur wrote:

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.

Ha! Who\'d\'a guessed?!

Thankfully, I didn\'t find this before discovering other options
else I would likely have \"settled\" for what appears to be a more
expensive option.

But, some of the offerings seem like they\'d be handy to have
on-hand just to compare to other approaches. All of the
ebay hits seem 404. But, alibaba shows promise.

Thanks!

 

[Dan Purgert]

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Don Y wrote:

On 1/27/2022 1:21 AM, whit3rd wrote:
On Wednesday, January 26, 2022 at 11:47:20 PM UTC-8, Don Y wrote:
On 1/26/2022 8:54 PM, whit3rd wrote:
On Wednesday, January 26, 2022 at 7:01:04 PM UTC-8, Don Y wrote:

But, if one end of the rivet remains \"blind\", you need something to
grab it/bite into it.

How about drive rivets?
\"Pop\" rivets?

No, not the apply-tension type, the apply-percussion type, that uses
a pin protruding from the head that is struck with a hammer...

But, presumably, the force required wouldn\'t *require* a hammer

Yes, the \"apply percussion\" type of rivets require a hammer (and usually
a form tool), and cannot be used in blind holes.

Industrial[1] options are basically an unthreaded bolt which you stick
through your piece. Then back the bolt with an anvil, and form the
other end with a hammer (and likely a form tool).

This is opposite to pop-rivets that we\'d pick up from a hardware store
where basically you have a pin with a sleeve around it. As you yank on
the pin, you deform the sleeve.

A simple (if labor intensive) approach for use around the home is tubes
of whatever metal you please (aluminum, brass, copper, steel, whatever),
a good sized bit of square steel, and a ball-peen hammer. (plus
ancillary tools to hold / cut the long tube)

- flare the end of the tube slightly with a few hits from the hammer
(use the peen end )
- cut the tube to sufficient length to fully pass through the parts
to be joined, plus 0.062\" to 0.125\" (1/16 to 1/8)
- stick tube through hole, with the initially flared end to the back
(or less-accessible side), and hold it tight with your steel block
- flare the front side (again, use the peen end)


[1]Well, at least when \"industry\" used rivets. These days, welding is
probably their goto. Loads of pictures available on the internet of
steelworkers riveting buildings or ships or trains, etc.

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|O|O|O|

 

[Don Y]

On 1/27/2022 4:36 AM, Dan Purgert wrote:

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Don Y wrote:
On 1/27/2022 1:21 AM, whit3rd wrote:
On Wednesday, January 26, 2022 at 11:47:20 PM UTC-8, Don Y wrote:
On 1/26/2022 8:54 PM, whit3rd wrote:
On Wednesday, January 26, 2022 at 7:01:04 PM UTC-8, Don Y wrote:

But, if one end of the rivet remains \"blind\", you need something to
grab it/bite into it.

How about drive rivets?
\"Pop\" rivets?

No, not the apply-tension type, the apply-percussion type, that uses
a pin protruding from the head that is struck with a hammer...

But, presumably, the force required wouldn\'t *require* a hammer

Yes, the \"apply percussion\" type of rivets require a hammer (and usually
a form tool), and cannot be used in blind holes.

The cited rivets appear to be \"pop rivets in reverse\". I.e., there is
a rod protruding from the *top* (formed) side of the rivet. As this
is pressed into the rivet body, the walls of the rivet are forced outward
in a manner similar (but different) to how the rod being *pulled* from
a pop rivet deforms THOSE walls.

Contrast with a \"regular\" rivet that requires a swage to form the
yet-unformed end of the rivet.

So, pressing (with sufficient force) on that pin will achieve the
same result as wacking it with a hammer. The question is: how
much force is required (cuz you are indirectly transferring that
force to the item into which the rivet is being installed!)

Drive rivet:
<https://cdn11.bigcommerce.com/s-c7chaa/images/stencil/1280x1280/products/719/1859/drive_rivet__63707.1517517434.jpg?c=2&imbypass=on>
note the \"split end\", at right, that is inserted into the hole.
The protruding rod remains *inside* the rivet after fastening.

Pop rivet:
<https://parts.pjtrailers.com/media/catalog/product/cache/1/image/1200x1200/9df78eab33525d08d6e5fb8d27136e95/1/8/180500b.jpg>
note the wide end, at left, that is drawn into the narrow body of the rivet.
The protruding rod is snapped off in the forming of the joint.

Rivet:
<https://en.wikipedia.org/wiki/Rivet#/media/File:Rivet01.jpg>
note the absence of any \"protruding rod/movable member\" within the
rivet\'s body; the end must be peened over to bind.

All of these leave you with an effectively \"solid\" rivet -- in that
there is no clear path through the rivet\'s body without some additional
labor step.

Industrial[1] options are basically an unthreaded bolt which you stick
through your piece. Then back the bolt with an anvil, and form the
other end with a hammer (and likely a form tool).

This is opposite to pop-rivets that we\'d pick up from a hardware store
where basically you have a pin with a sleeve around it. As you yank on
the pin, you deform the sleeve.

A simple (if labor intensive) approach for use around the home is tubes
of whatever metal you please (aluminum, brass, copper, steel, whatever),
a good sized bit of square steel, and a ball-peen hammer. (plus
ancillary tools to hold / cut the long tube)

- flare the end of the tube slightly with a few hits from the hammer
(use the peen end )
- cut the tube to sufficient length to fully pass through the parts
to be joined, plus 0.062\" to 0.125\" (1/16 to 1/8)
- stick tube through hole, with the initially flared end to the back
(or less-accessible side), and hold it tight with your steel block
- flare the front side (again, use the peen end)

[1]Well, at least when \"industry\" used rivets. These days, welding is
probably their goto. Loads of pictures available on the internet of
steelworkers riveting buildings or ships or trains, etc.

 

[Don Y]

On 1/26/2022 6:41 AM, legg wrote:

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?

Look at bicycle caliper brake adjustment hardware.

Thread OD typically 0.225in - possibly an M5 or M6 thread.

That\'s an idea! I\'ve not owned a bike in years so can\'t recall
the details but I do recall their presence by the brake levers
(effectively altering the ratio of inner cable to outer sheath)

 

[Lasse Langwadt Christensen]

torsdag den 27. januar 2022 kl. 14.27.49 UTC+1 skrev Don Y:

On 1/27/2022 4:36 AM, Dan Purgert wrote:
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Don Y wrote:
On 1/27/2022 1:21 AM, whit3rd wrote:
On Wednesday, January 26, 2022 at 11:47:20 PM UTC-8, Don Y wrote:
On 1/26/2022 8:54 PM, whit3rd wrote:
On Wednesday, January 26, 2022 at 7:01:04 PM UTC-8, Don Y wrote:

But, if one end of the rivet remains \"blind\", you need something to
grab it/bite into it.

How about drive rivets?
\"Pop\" rivets?

No, not the apply-tension type, the apply-percussion type, that uses
a pin protruding from the head that is struck with a hammer...

But, presumably, the force required wouldn\'t *require* a hammer

Yes, the \"apply percussion\" type of rivets require a hammer (and usually
a form tool), and cannot be used in blind holes.
The cited rivets appear to be \"pop rivets in reverse\". I.e., there is
a rod protruding from the *top* (formed) side of the rivet. As this
is pressed into the rivet body, the walls of the rivet are forced outward
in a manner similar (but different) to how the rod being *pulled* from
a pop rivet deforms THOSE walls.

Contrast with a \"regular\" rivet that requires a swage to form the
yet-unformed end of the rivet.

So, pressing (with sufficient force) on that pin will achieve the
same result as wacking it with a hammer. The question is: how
much force is required (cuz you are indirectly transferring that
force to the item into which the rivet is being installed!)

Drive rivet:
https://cdn11.bigcommerce.com/s-c7chaa/images/stencil/1280x1280/products/719/1859/drive_rivet__63707.1517517434.jpg?c=2&imbypass=on
note the \"split end\", at right, that is inserted into the hole.
The protruding rod remains *inside* the rivet after fastening.

Pop rivet:
https://parts.pjtrailers.com/media/catalog/product/cache/1/image/1200x1200/9df78eab33525d08d6e5fb8d27136e95/1/8/180500b.jpg
note the wide end, at left, that is drawn into the narrow body of the rivet.
The protruding rod is snapped off in the forming of the joint.

Rivet:
https://en.wikipedia.org/wiki/Rivet#/media/File:Rivet01.jpg
note the absence of any \"protruding rod/movable member\" within the
rivet\'s body; the end must be peened over to bind.

All of these leave you with an effectively \"solid\" rivet -- in that
there is no clear path through the rivet\'s body without some additional
labor step.

you can get threaded pop rivets, once you have pulled the stem to set the rivet it doesn\'t snap, instead it unscrews leaving a threaded hole

 

[bilou]

Le 26/01/2022 à 17:41, Lasse Langwadt Christensen a écrit :

onsdag den 26. januar 2022 kl. 10.48.31 UTC+1 skrev Don Y:
On 1/26/2022 1:44 AM, Mikko OH2HVJ wrote:
Why wouldn\'t I thread the screw into a tapped block (to support and
reinforce the threads -- as well as act as a heat sink) -- after coating
it with antiseize (as the drill bit\'s rotation will tend to want
to tighten the screw in the block, possibly making removal more
difficult)?

because it is much easier to keep the drill centered by spinning the part
instead of the drill, try it ..

https://youtu.be/v5yx1C-maRo

+1
It can even be used with hand tools.
With care you can drill a hole almost twice as long as the drill bit.
Try it