"Hollow" screw

On 1/29/2022 9:04 AM, legg wrote:
> On Fri, 28 Jan 2022 19:43:26 -0700, Don Y
> <blockedofcourse@foo.invalid> wrote:
> 
>> On 1/28/2022 6:29 AM, legg wrote:
>>> On Thu, 27 Jan 2022 06:29:31 -0700, Don Y
>>> <blockedofcourse@foo.invalid> wrote:
>>>
>>>> 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)
>>>
>>> Tends to be Aluminum in the caliper adjustment, but longer and
>>> brass in the presta valve. Tubes are easier to come by and are
>>> regularly trashed, so maybe easier to get.
>>
>> So, unlike the practice (as a kid) of *patching* a tube for reuse,
>> they are now considered "disposable"?  (or, has some aspect changed
>> that makes patching impractical)
>>
>> OK, so my neighbor (semi-professional rider who does these 100-mile
>> "tours") won't be "put out" by my asking him to save his next flat
>> for me?  (or, canvas his friends for one)
>>
>> I know he volunteers at a local non-profit that builds bikes for
>> underprivileged kids.  Would those types of builds use tubes with
>> that valve?  Or, would they still be Shrader?  (i.e., how likely
>> would that group be as a source of a "bad tube"?)
>>
>> Thanks!
> 
> Real bike nuts use some kind of strange tubeless concoction.
> 
> Your local bike or sports store will stock tubes with either
> presta or schraeder valves. Schraeders aren't any use to you.
> 
> If they've got a repair department they'll likely have a handfull
> of old tubes in their garbage. New tubes can be had for <$5.

I'd rather find a "waste" tube that I can cannabilize and replace it
with a new tube -- than buy a new tube just to cut it up!  That's
why the question re: the sorts of tubes the charity would likely
be using (needing).

> I carry patched spares in my bike tool kit, because repairs on
> the road are quicker that way, and patching works better in
> a dry, well-lit and heated environment.

No doubt!  Not to mention the lack of urgency that it affords.

I don't think I ever was far enough from "home", with a flat, that it
was an issue.  But, my longest rides were ~50 mi (25 out and 25 back)
and, in a pinch, I could always phone for a lift home (as a teenager).

Folks routinely ride up/down the mountain, here ("training") and I
pity them if they had an incident; there's NOTHING along the way
and you're dealing with 55MPH traffic at the same time with hardly
a shoulder to rely on (one side is rock face, the other is cliff)

It seems like bike riding was less risky when I was younger...

On 1/28/2022 11:45 PM, whit3rd wrote:
> On Tuesday, January 25, 2022 at 10:24:58 PM UTC-8, Don Y wrote:
>> I need ...a threaded tube (NOT
>> a pipe nipple). But, getting premade threaded tubing in that
>> range seems difficult.
> 
> If you can CAD the shape and pick a material from a list,
> there's online shops that'll do the rest for ya.
> 
> <https://www.emachineshop.com/start/>
> 
> A threaded tube is just chuck a rod, drill on axis,
> turn to diameter, thread, and part off, robotic lathes can do it quick and easy.

The "free/exposed end" will require more treatment.  (there are several
different "profiles" required -- but, these only affect the exposed
portion of the fastener)

My current plan is to accumulate COTS samples of parts and evaluate them
as to strength, deformation, etc.  (it's one thing to have a number that
alleges to represent the torque limits of a design -- another thing to
actually subject that to the torque from your hand/tool/etc. and observe
the results).  From that, settle on a wall thickness and fine-tune the
profiles (e.g., to make them "less encouraging" to folks who may be tempted
to "unfasten" them)

[BTW, the "drive rivets" that I found at the local hardware require far
too much force to deform.  That force would be carried through to the
rest of the unit.  A *pop* rivet localizes the force between the
rivet and the tool so there is no risk of damage to the rest of the
device as the rivet is deformed.]

Then, research manufacturing tolerances for the different materials/markets
involved and try to find a "common denominator" that allows one set of
drawings to address the different designs.

On Sun, 30 Jan 2022 00:08:54 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:

<snip>
>>> I know he volunteers at a local non-profit that builds bikes for
>>> underprivileged kids.  Would those types of builds use tubes with
>>> that valve?  Or, would they still be Shrader?  (i.e., how likely
>>> would that group be as a source of a "bad tube"?)
>>>
>>> Thanks!
>> 
>> Real bike nuts use some kind of strange tubeless concoction.
>> 
>> Your local bike or sports store will stock tubes with either
>> presta or schraeder valves. Schraeders aren't any use to you.
>> 
>> If they've got a repair department they'll likely have a handfull
>> of old tubes in their garbage. New tubes can be had for <$5.
>
>I'd rather find a "waste" tube that I can cannabilize and replace it
>with a new tube -- than buy a new tube just to cut it up!  That's
>why the question re: the sorts of tubes the charity would likely
>be using (needing).
>
>> I carry patched spares in my bike tool kit, because repairs on
>> the road are quicker that way, and patching works better in
>> a dry, well-lit and heated environment.
>
>No doubt!  Not to mention the lack of urgency that it affords.
>
>I don't think I ever was far enough from "home", with a flat, that it
>was an issue.  But, my longest rides were ~50 mi (25 out and 25 back)
>and, in a pinch, I could always phone for a lift home (as a teenager).
>
>Folks routinely ride up/down the mountain, here ("training") and I
>pity them if they had an incident; there's NOTHING along the way
>and you're dealing with 55MPH traffic at the same time with hardly
>a shoulder to rely on (one side is rock face, the other is cliff)
>
>It seems like bike riding was less risky when I was younger...

It probably seems that way when you're younger and are unaware 
of the hazards, but higher density traffic does require common 
sense and defensive driving/riding techniques. Oldsters don't 
ride bikes the same way that youngsters do.

I ride for transportation, so a 10 minute delay for a tube changeout 
has to be budgeted in a sensibly less-than-45-minute commute 
(this being a consideration before negotiating a job or accomodation).
We get snow here, so there are days when the weather sensibly calls 
for shanks mare or public transit (where available). You should know 
that the road surface is stable along your route - makes lane sharing 
with 6 ton behemoths more practical.

I maintain two bikes - one with 32C Schraeder-valve tires that never 
go flat and a fancier spare with 24C presta-valve tires that go flat 
if you look at them the wrong way.

If you don't remove a holed tube quickly, it can be rendered 
unpatchable - a practice that produces a lot of trashed tubes.
Bike repair guys also will replace rather than repair a leaking 
tube - its an FRU that's cheaper to replace than to troubleshoot, 
as with a lot of things these days.

RL

On 1/30/2022 9:44 AM, legg wrote:
> On Sun, 30 Jan 2022 00:08:54 -0700, Don Y

>> I don't think I ever was far enough from "home", with a flat, that it
>> was an issue.  But, my longest rides were ~50 mi (25 out and 25 back)
>> and, in a pinch, I could always phone for a lift home (as a teenager).
>>
>> Folks routinely ride up/down the mountain, here ("training") and I
>> pity them if they had an incident; there's NOTHING along the way
>> and you're dealing with 55MPH traffic at the same time with hardly
>> a shoulder to rely on (one side is rock face, the other is cliff)
>>
>> It seems like bike riding was less risky when I was younger...
> 
> It probably seems that way when you're younger and are unaware
> of the hazards, but higher density traffic does require common
> sense and defensive driving/riding techniques. Oldsters don't
> ride bikes the same way that youngsters do.

Most (all?) of my bike-riding happened before I went off to
school as I wasn't old enough to drive.  Yet, still needed
to get myself to the various "gifted student" programs in
which I was enrolled (hence the 25 miles each way) on weekends
and summer days -- both times when my folks were unavailable to
schlep me around!

Back then, a "highway" was two lanes (one each direction) with
a generous shoulder.  And, traffic volume was lighter.

And, I could exploit back roads to avoid the majority of traffic
(save for a few stretches) or exploit the topography.

Here, OTOH, the road onto which my subdivision empties is 6 lanes
and has a posted speed limit of 45MPH -- which means 55MPH is the
nominal rate of travel (for motor vehicles).

[The speed limit in town is 45 for most roads; 25 in "neighborhoods"]

On a two-lane road, you can sit on the right shoulder and still
manage to make a left across traffic.

On a 6-lane road -- with two more lanes for turns -- you really
have to be in the left lane in order to turn left.  And, once
you've navigated the turn, you now find yourself in the left lane
trying to get back over to the right shoulder!  :<

[We have a fair number of bicyclists, pedestrians, etc. involved
in accidents because of the mismatch between motor vehicle operators
and these "burdened" forms of travel]

> I ride for transportation, so a 10 minute delay for a tube changeout
> has to be budgeted in a sensibly less-than-45-minute commute
> (this being a consideration before negotiating a job or accomodation).

As was the case for me.  But, I was going to *class* so there's not
as much downside to being delayed as there would be with an
employer.

> We get snow here, so there are days when the weather sensibly calls
> for shanks mare or public transit (where available). You should know
> that the road surface is stable along your route - makes lane sharing
> with 6 ton behemoths more practical.

I recall my first discovery of the value of "fenders" the first time
traveling in inclement weather.  Moral of story:  wear a light jacket
if only to protect the back of your shirt!  :<

> I maintain two bikes - one with 32C Schraeder-valve tires that never
> go flat and a fancier spare with 24C presta-valve tires that go flat
> if you look at them the wrong way.

I will keep that in mind if I ever opt to purchase a bike.  Though
I imagine my riding days are behind me (I walk to places that most
folks would ride for the value of the exercise -- most trips, here,
are < 4mi each way:  library, post office, grocers, etc.)

> If you don't remove a holed tube quickly, it can be rendered
> unpatchable - a practice that produces a lot of trashed tubes.
> Bike repair guys also will replace rather than repair a leaking
> tube - its an FRU that's cheaper to replace than to troubleshoot,
> as with a lot of things these days.

That was what I had suspected.  As a kid, buying a replacement
was unheard of -- you fixed what you had!  And, as it was impractical
to ride on a flat, you "hoofed it" when the tire gave up the ghost.

Don Y <blockedofcourse@foo.invalid> writes:
> On 1/26/2022 1:44 AM, Mikko OH2HVJ wrote:
>> with a drill press by fixing the screw to the chuck and having the drill
>> bit stationary. Drill a starting hole with larger drill and through with
>> a smaller one(s).

> 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)?

Centering is way easier that way. If you want to have any larger hole,
you'll damage the threads with non-centered hole.

> And, I'd assume move from smaller diameter bits up through larger ones
> to minimize the amount of material being removed with each.

Nope, make a small starting indent first with an oversize drill. A
center drill would be the correct tool, but I assumed you would not have
that (nor lathe).

--
mikko