footstrap screws
grayson
sheetmetal screw and if it strips out the insert then use the next
size up" to the other end of the spectrum "you must use the exact same
screw in order to match the threads perfectly". i tend to agree more
with the later approach (or something close to it), and i'm trying to
add some spare footstrap screws to my repair kit. anybody have
insights to share about footstarp screws? specifically, what are the
dimensions and thread pitch of common footstrap screws? are they
significantly different between different manufacturers? where can i
get them? i see that www.the-house.com has chinook brand footstrap
screws. are these the same (at least in thread pitch and major
diameter) as the ones that come with most production boards?
in a post from 2002 (http://tinyurl.com/29w8av) roger jackson
responded with some interesting details about the so-called "PT"
screws commonly used for footstraps, and mentioned a chart he had put
together of screw specifics for various starboard boards. but he
didn't mention any specs like thread pitch, root diameter, helix
angle, etc, or where to get replacement screws. if roger or anybody
else can chime in with a little more detail i think this is
information that many of us could use.
sail...@mindspring.com
Yes, I put the original chart for Starboard footstrap screws together
way back in 2001 or 2002.
It's still there, with the drawings and specifications.
The reason I can't give you the specific engineering data on the
screws is that it's basically
"proprietary" to Textron who originally developed this thread form for
thermoplastics.
The flank angle on the threads is 30 deg. (vs 60 deg. for threaded
metal fasteners (i.e common nuts and bolts)).
You can see the drawings and specs. at:
http://www.star-board.com/viewpage.php?page_id=22
(Click the link and go all the way to the bottom and you will see
quite a bit)
of engineering data on PT screws.
They are not sheet metal screws at all. Thread form is very different.
Best way to fix a stripped footstrap screw is to use the procedures
I've suggested at:
http://www.star-board.com/viewpage.php?page_id=21
(Click the link and go down the page to "How to repair damaged
footstrap inserts.)
You can probably get the screws from your local windsurfing shop.
AFAIK the Chinook footstrap screws should be 6mm PT just like the rest
of the industry uses.
Hope this helps,
R
On May 9, 1:13 am, grayson <grayson.k...@gmail.com> wrote:
> i've seen conflicting advice on footstrap screws varying from "use any
> sheetmetal screw and if it strips out the insert then use the next
> size up" to the other end of the spectrum "you must use the exact same
> screw in order to match the threads perfectly". i tend to agree more
> with the later approach (or something close to it), and i'm trying to
> add some spare footstrap screws to my repair kit. anybody have
> insights to share about footstarp screws? specifically, what are the
> dimensions and thread pitch of common footstrap screws? are they
> significantly different between different manufacturers? where can i
> get them? i see thatwww.the-house.comhas chinook brand footstrap
rod.r
I started this thread a while ago about having a single or double back
footstrap and it ended up being a very informative
thread on pt screws, with roger giving us all a lesson on what they
are and how to install them.
i just bought a 2001 starboard f155 woodie and the first thing i did
was to take off all the straps and have alook at the screws
and lucky i did because one of the straps had non pt screw screws
which i swapped for the proper screw.
you'll know right off if it's the wrong screw as the pt screws have
quite a large gap between threads
with the threads themselvs being quite "meaty". the wrong screw in
this case had small fine closely spaced threads
even though the shaft appeared to be the same diameter.
Tsunami
"grayson" <grayso...@gmail.com> wrote in message
news:1178687632....@l77g2000hsb.googlegroups.com...
My only thoughts: every footstrap screw I've ever seen has been about 20-30
thou too long. Grind off the point by about that amount (0.5 - 0.75 mm).
For anyone who doesn't know: spread a bit of soap on them 1st time in, and
they go in a lot easier!
and when they strip out: just put two matchsticks in the hole and screw
back in. Sometimes that is not quite enough, I may use a sliver of hardwood
about 1/8 diameter
grayson
still more great info from roger. interesting comments on use of
power tools being a bad idea. very good to know. also great
suggestions on the starboard website for fixing stripped fin screw
inserts. as an engineer myself, i sure appreciate roger's engineering
approach to issues like this. :)
ANYWAY.... i have a follow-on question or two. the specs on the PT
screws from roger's first link leave out one very important detail (or
i missed it). i didn't see any reference to thread pitch. so i did a
quick google search and found detailed specs on PT screws at the
following pages:
http://mdmetric.com/prod/keba/prod_kpt.html
http://www.harrison-silverdale.co.uk/type.asp?id=132
http://www.specialisedfasteners.co.uk/cat-03-page-22.lasso
these say that the thread pitch for a K60 (6mm OD) PT screw is
2.69mm. i pulled a footstrap screw from my bic techno2 this morning
and it appears to have a tread pitch right around 2.60mm. definitely
smaller than 2.69mm anyway. it has the same 6mm OD as the PT screw,
but has a different thread core diameter (~4.33mm rather than
3.19mm). this is clearly not the same screw, but is pretty similar.
how many different footstrap screw types are there?? does anybody
know what the "chinook" footstrap screws are that www.the-house.com is
selling?
wind.sh@dow
<snip>
> does anybody
>know what the "chinook" footstrap screws are that www.the-house.com is
>selling?
Not meant to diss The House, but if I were going to buy Chinook screws
and wanted to be sure I was getting them, I might call a smaller
dealer. Footstrap screws tend to look alike and I think there is a
good chance of them getting mixed up at a big store.
grayson
> Not meant to diss The House, but if I were going to buy Chinook screws
> and wanted to be sure I was getting them, I might call a smaller
> dealer. Footstrap screws tend to look alike and I think there is a
> good chance of them getting mixed up at a big store.
thanks wind.sh@dow, good suggestion. i only mention the-house because
theirs is the only web reference to the chinook footstrap screws (or
any footstrap screws for that matter). even chinook's website doesn't
show them. chinook's wesite does mention footstrap screws in the
"components" section, but all it says is "1/4-20 and 6mm sizes" so
clearly someone is confused since those certainly aren't footstrap
screws unless you're dealing with a really old or custom board with
threaded brass inserts. the photo on the-house's webpage (http://
www.the-house.com/ch610zzchinook.html) clearly shows what looks to me
like a real footstrap screw (it's definitely not 1/4-20 or M6 anyway),
so i wondered if anybody might know what these are.
wind.sh@dow
>thanks wind.sh@dow, good suggestion. i only mention the-house because
>theirs is the only web reference to the chinook footstrap screws (or
>any footstrap screws for that matter). even chinook's website doesn't
>show them. chinook's wesite does mention footstrap screws in the
>"components" section, but all it says is "1/4-20 and 6mm sizes" so
>clearly someone is confused since those certainly aren't footstrap
>screws unless you're dealing with a really old or custom board with
>threaded brass inserts. the photo on the-house's webpage (http://
>www.the-house.com/ch610zzchinook.html) clearly shows what looks to me
>like a real footstrap screw (it's definitely not 1/4-20 or M6 anyway),
>so i wondered if anybody might know what these are.
Sure thing, grayson. BTW, Chinook answers the phone and they are
terrific folks.
grayson
> Sure thing, grayson. BTW, Chinook answers the phone and they are
> terrific folks.
another good suggestion wind.sh@dow, thanks for that. you're right,
they do answer the phone at chinook. and you're right, they are
terrific folks; or at least dan, to whom i just spoke, seems to be.
dan had some interesting info for me. apparently chinook recommends
regular #10 or #12 sheetmetal screws for the inserts that they make,
and they recommend that if the #10 strips out, then just install a #12
and you'll be fine. dan wasn't aware that there was more than one
type of "self tapping" screw out there (like the PT screws that are
used in the starboard boards or the similar but slightly different
screws that came with my bic boards). so i've sent an email off to
bic to see if they can tell me what they use. geze, is it just me, or
is this a lot more complicated than it ought to be? i'll certainly
post again when i hear from bic in hopes that others are able to use
the info that's accumulating in this thread. meantime, if anybody
else has additional info/insights on the various kinds of footstrap
insert screws out there i hope they'll post as well.
a_m...@yahoo.com
> On May 9, 1:29 pm, "wind.sh@dow" <just lurking> wrote:
>
> . geze, is it just me, or
> is this a lot more complicated than it ought to be?
You're right, it is a lot more complicated than it should be. And it
all could be so much simpler if every board came with two-hole inserts
- that way, you wouldn't have to worry so much about really cranking
down on the screws in order to really engage whatever chintzy plastic
anti-twist device comes with your board. All my Roberts boards have
double hole inserts, and I've never had a problem with twist, and I've
never had a problem with stripping the insert (since it doesn't
require the insane amounts of force to secure your straps as you would
have with the OEM single-hole-plus-stupid-anti-twist-device setup). I
know, the OEM's have really gotten most of that anti-twist stuff to
work - but why bother in the first place and not just give us decent
double-screw setups? Better distribution of force that way, too - so
ripping out a strap insert is less likely as well. And I'll get off my
little soapbox now...
-Andreas
http://g-42.blogspot.com
grayson
> You're right, it is a lot more complicated than it should be. And it
> all could be so much simpler if every board came with two-hole inserts
amen to that andreas, that sure would be nice. i really like the
double-screw inserts on my mike's lab board. wish all production
boards were like that. even if they were though, i'd still like to
see the industry standardize on one type of screw. replacing a lost
screw with one that has a slightly different thread pitch or
dimensions seriously weakens the formed threads. that's just basic
physics. windsurfers replace or adjust footstraps and lose footstrap
screws all the time, so why can't the industry standardize on one type
of screw? seems like the standard K60 PT screws would be the way to
go, so i'm not sure why the ones in my bic boards are just slightly
different in pitch and core diameter, but i hope to find out from bic
and post back with answers.
wind.sh@dow
I don't doubt sailquik's knowledge or advice, but wonder just how many
people that sail way more than most of us go to the effort to find the
exact screw they need. I've never needed Tsunami's matchstick trick
for a footstrap insert, although I've used the trick lots around the
house. But the straps on at least 2/3 of the 20 or so boards I've
owned rarely got loose and I'd be amazed if they all had the stock
screws.
sail...@mindspring.com
> On 9 May 2007 18:38:06 -0700, grayson <grayson.k...@gmail.com> wrote:
Well, my advice, and the things that were developed for Starboard were
the fruits
of alot of research on the internet and in plastics and composites
text books, plus
about 20 years of experience.
Most new boards come with a set of footstraps, with the correct
screws, that's
pretty simple.
Then comes the "once in a board's life opportunity".
If you soap the screws as suggested, and use the correct tool (a hand
driven
screwdriver with the correct drive configuration), install them with
the correct
hardware and anti-twist devices, you can go back once, a couple of
sessions
later, and snug the screws up one more time.
If you follow the above suggestions, when the board is new, the
footstrap screws will
last the life of the board.
Don't use the soap as a lubricant...... the threads don't form in the
insert correctly.
Use a power screwdriver.... you might just "melt or heat damage" the
plastic insert with
the rotational friction developed by driving the screws in under
power.
As I usually have 20 or more boards in the demo fleet, over the past 7
years, that's alot of
boards, and I've never had a footstrap screw pull out. These demo
boards get quite a bit of use.
As far as matchsticks stuck down the hole, that could be a jury rig
fix that might get you a few
more sessions before the screw pulls out completely, but the use of
the Permatex or Lock tite
thread repair is a permanent fix that makes the pull out strength
higher than it was with the
stock screw in a new insert. I've repaired many a vent fitting and
quite a few footstrap inserts this way
and I've never had one fail afterwards.
The PT screws were originally developed to fill an industrial
requirement where plastic parts needed to be
assembled more permanently, with the best possible fastener integrity.
There's a metric equivalent ( a DIN spec I believe) and that could be
the difference between PT type screws
made/used in Europe (France especially now) and the Cobra factory in
Thailand which buys footstrap screws
to their own spec. by the 100's of thousands each year.
Buy a Cobra built board and you get Cobra spec's FS screws. Buy a BIC
board and you most likely get either
DIN spec. PT type screws or something made to a BIC spec.
So, if you install the correct screws, correctly, you most likely will
never need to replace even one of them.
If you use something else, or don't take the necessary precautions to
install them, you may need alot of them and
perhaps not be able to get identical replacements.
Hope this helps,
>
> I don't doubt sailquik's knowledge or advice, but wonder just how many
> people that sail way more than most of us go to the effort to find the
> exact screw they need. I've never needed Tsunami's matchstick trick
> for a footstrap insert, although I've used the trick lots around the
> house. But the straps on at least 2/3 of the 20 or so boards I've
> owned rarely got loose and I'd be amazed if they all had the stock
>
> - Show quoted text -
grayson
<sailq...@mindspring.com> wrote:
<snip>
> So, if you install the correct screws, correctly, you most likely will
> never need to replace even one of them.
> If you use something else, or don't take the necessary precautions to
> install them, you may need alot of them and
> perhaps not be able to get identical replacements.
> Hope this helps,
thanks roger. yes, that does help. however, the reality is that
footstrap screws do get lost. i change my footstraps twice a season:
to a wider pair of holes to accomodate my cold-water booties, then to
a narrower normal pair of holes to accomodate my bare feet and warm-
weather reef booties. that's a lot of opportunity for losing screws,
and i've had a couple close calls recently. i'd really prefer to not
lose a session, or be forced to use whatever's available, when murphy
finally strikes. so i'm looking for spare replacement screws now.
amazing what i'm having to go through just to find the right screw
instead of accepting a "whatever works" approach that'd certainly
compromise the strength of the insert.
sail...@mindspring.com
Not to be argumentative here, but why do you need to completely remove
the footstrap screws just to move them to the next hole in the insert?
I move FS screws to wider holes for some demo customers, and it's
simply a matter of unscrewing the screw until it
releases from the insert, pulling the footstrap up and away enough so
I can pry out the K9 anti-twist plate, moving the K9 plate to the new
hole I'll be using,then putting some soap (from a bar of soap) on the
threads of the screw and retightening the assembly.
The FS screw never gets removed from the hole in the footatrap.
Also, why move them....?
If you set your footstraps one hole wider than "front hole to front
hole" or "back hole to back hole", they accomodate many different foot
sizes (even most booties) and you can simply cinch up or release the
velcro'ed internal straps to make the footstrap fit your foot or
bootie.
Having them a little wider is a good thing (to me anyway) as it allows
you to get your foot in easier, and allows you to twist your foot
along the rail to apply the pressure (or leverage) in slightly
different positions which can do some really good things for your
sailing.
I set all the footstraps on the demo boards this way (back hole in the
back insert, middle hole in the front insert) and it
works quite well.
Yes, I understand that some folks want their footstraps really tight
on the sides of their foot, but I often wonder if this is some sort of
"anal about symmetry" thing, where they've never really tried the
footstraps wider, or if they've ever tried the wider screw setting and
found that it really doesn't work for them.
Footstraps are there to keep your foot in contact with the board, and
you can make that happen by tightening the footstrap adjustment.
Try the wider setting this summer and let me know how much difference
(other than the initial "feel") it makes. You may find you like it
alot, as I have.
Hope this helps,
shre...@charter.net
Roger I just had a footstrap screw break off! It was an original screw
on an AHD Free Diamond 2000ish board. All of a sudden The footstrap
was no longer connected in the front and on inspection I see it
snapped in two and the other half is in the board and I haven't
figured a way to get it out yet.
wind.sh@dow
<sail...@mindspring.com> wrote:
>On May 9, 9:54 pm, "wind.sh@dow" <just lurking> wrote:
>> On 9 May 2007 18:38:06 -0700, grayson <grayson.k...@gmail.com> wrote:
>Well, my advice, and the things that were developed for Starboard were
>the fruits
>of alot of research on the internet and in plastics and composites
>text books, plus
>about 20 years of experience.
<snip>
Now *there* is a keeper post if I ever saw one. This should come with
all new boards. Thanks, Roger!
sail...@mindspring.com
> Roger I just had a footstrap screw break off! It was an original screw
> on an AHD Free Diamond 2000ish board. All of a sudden The footstrap
> was no longer connected in the front and on inspection I see it
> snapped in two and the other half is in the board and I haven't
> figured a way to get it out yet.
>
> On May 9, 11:12 pm, grayson <grayson.k...@gmail.com> wrote:
That's probably the worst thing that can happen and is usually the
result of
someone (maybe not you) driving the screws in with a power screwdriver
and
"overtorqueing them to the point that it fatigues the minor diameter
of the threaded
portion of the screw.
If there's any of the screw still sticking out of the insert,
sometimes you can grab the
stub that's still in the board with vice grips and turn the broken
piece anti-clock wise and
unscrew the broken stub out of the insert..
Once it's out, a new screw, properly lubed with soap and torqued,
( you almost cannot overtorque
these screws by hand, it's really running them in fast and expecting
the "torque limiter" on the
power screwdriver to release at the correct torque that normally
results in the over torque)
will give you as much pull out strength as the original.
If you can't get the stub out, you will be forced to have the insert
replaced (best done by professional board repair
shops that have the skills, tools, and materials to do it right) or
use an adjacent hole in the insert.
Trying to drill out a broken SS screw in a plastic insert is next to
impossible without some fancy machinery and special
hollow drill bits.
Did the screw break off right under the head, or further down in the
hole?
Hope this helps,
sail...@mindspring.com
Since nearly all sailboards are made at the Cobra factory these days
(except customs like Mike's Labs and Bics)
and also since Cobra has used the same exact footstrap screw (K60 x 28
mm PT) for all Starboards (and probably all the other boards they
manufacture there) getting the right footstrap screw is pretty easy.
Call who ever made your board (nearest dealer, and the nat'l
distributor if the dealer can't/won't help) and get a few replacement
screws.
Since you have a BIC board, I'd check with your local BIC dealer, and
if they can't/won't help then call the distributor:
http://www.bicsportna.com/BICSurfPR8_30_05.pdf
There are phone numbers and email contacts on the link.
I'll bet they can supply precisely the screws you need. BIC probably
uses the same FS screws in all of their boards, same as Cobra does
with all the other brands.
Hope this helps
shre...@charter.net
there is nothing sticking out. I have moved the strap for now and may
have to just keep it in the new spot. Yeah I thought drilling would be
a real bare. Funny thing though, I am the one who put it in when I
replaced the footstraps but only used a big fat srewdriver to do it?
Maybe I am too strong and torqued it down to the breaking point Ha
Ha Ha!
On May 10, 12:33 pm, "sailq...@mindspring.com"
sail...@mindspring.com
> On 9 May 2007 21:08:53 -0700, "sailq...@mindspring.com"
>
> <sailq...@mindspring.com> wrote:
> >On May 9, 9:54 pm, "wind.sh@dow" <just lurking> wrote:
> >> On 9 May 2007 18:38:06 -0700, grayson <grayson.k...@gmail.com> wrote:
> >Well, my advice, and the things that were developed for Starboard were
> >the fruits
> >of alot of research on the internet and in plastics and composites
> >text books, plus
> >about 20 years of experience.
>
> <snip>
>
> Now *there* is a keeper post if I ever saw one. This should come with
> all new boards. Thanks, Roger!
Not sure if you are being facetious on not there.
The information was developed to assist Starboard customers and is
freely available to anyone on the planet:
Here's the link to how to repair boards plus additional info on how to
repair stripped footstrap screw inserts/vent plugs:
http://www.star-board.com/viewpage.php?page_id=21
Here's the link to a list of Starboard fin screws and footstrap
screws, with some engineering
data (DIN specs and such) at the end.
http://www.star-board.com/viewpage.php?page_id=22
Here's a link to a huge .PDF file that will provide you with
everything you want to know about
PT screws and the R&D that Textron did originally.
http://www.textronfasteningsystems.com/PDFs/plastics/FFPbook.pdf
Here's the engineering data for the Textron developed K60 x 28 mm
screws all Starboards come equipped with.
Nom.Size: K60
Metric Thread Size: M6.0
P Thread Pitch: 2.69 mm
Major dia. Size: 6.00 mm
Minor dia. Size: 3.19 mm
So there you have it.
Hope this helps,
outdrsmn
> The screw pretty much broke off right at the height of the board and
> there is nothing sticking out. I have moved the strap for now and may
> have to just keep it in the new spot. Yeah I thought drilling would be
> a real bare. Funny thing though, I am the one who put it in when I
> replaced the footstraps but only used a big fat srewdriver to do it?
> Maybe I am too strong and torqued it down to the breaking point Ha
> Ha Ha!
>
Shred,
A reverse cut drill bit and an easyout should remove the screw shank.
A lot of times the reverse bit will actually be enough to start
backing the screw shank out on is own. Just use a battery operated
drill with good torque and go slow, you don't want to build up any
heat. You can even run some water over it to keep it cool. If you
hand tighened it then the likely cause of failure is an isolated
manufacturing defect. The smallest imperfetion or slight contamination
of the steel can cause a failure. Plus stainless isn't as strong as
most people think, it mainly has good corrosion and vibration
resistance.
Dan Weiss
To further C's post, it is s.o.p. to "tighten" a stuck bolt (even if
its doesn't appear to turn) just a bit to allow it to "unstick" itself
from whatever medium in resides. I'm not sure what an easy out is,
but you can oven cut a groove with a small rotary tool sufficient to
use a flat head driver to back the screw out.
-Dan
grayson
> A reverse cut drill bit and an easyout should remove the screw shank.
> A lot of times the reverse bit will actually be enough to start
> backing the screw shank out on is own. Just use a battery operated
> drill with good torque and go slow, you don't want to build up any
> heat. You can even run some water over it to keep it cool. If you
> hand tighened it then the likely cause of failure is an isolated
> manufacturing defect. The smallest imperfetion or slight contamination
> of the steel can cause a failure. Plus stainless isn't as strong as
> most people think, it mainly has good corrosion and vibration
> resistance.
hey great tip outdrsmn!! i went looking for such tools and found a 2-
in-1 reverse cut drill bit + extractor at mcmaster-carr. check
www.mcmaster.com and search for part number 53405A43. i'm pretty sure
that's the kind of tool you were talking about, yes? maybe use a pair
of vice-grips for the extraction step since i doubt you'd want to do
that part with the drill. anyway, for shred's board, this $12 tool
might be worth a shot before paying a *lot* more to have the insert
replaced by a board repair expert. good tip about running water over
it while drilling too.
p.s. i wasn't able to find any reverse cut drill bits available
separately. custom-cut tooling perhaps?
wind.sh@dow
>... you can oven cut a groove with a small rotary tool sufficient to
>use a flat head driver to back the screw out.
>
>-Dan
That's a great tip, I've done it many times using a flat cutoff disc
in the Dremel.
wind.sh@dow
<sail...@mindspring.com> wrote:
>Not sure if you are being facetious on not there.
Not in the least, why would you think so?
sail...@mindspring.com
Sorry, but this is a bad idea.
This is not a 1/4-20 bolt, or even a #6-32 screw thread!
The minor dia. of the screw is 3.8 mm (I just measured one with a
pretty accurate
digital vernier caliper).
3.8 mm is 0.1496 inches.
And, its austenintic (A4) (similar to 17-4 PH) or 304 RES) non-
magnetic
stainless steel.
I spent 20 years in Naval shipyards, in tool rooms, and I was never
very successful at
drilling out stainless fasteners smaller than about 1/4" which have a
minor dia. of
approx. 0.194 ".
Smaller than this, even using a precision milling machine or jig bore,
it's very hard to
drill something this small with a tiny .125-.187" drill.
This material tends to "work harden" as soon as you start to drill it,
and once it work hardens,
forget drilling it with a normal drill.
Yes, on very intricate (also very expensive) electronics assemblies,
or missle hydraulics components, we could
sometimes extract the screw, or drill it out to the max. tap drill
size for the thread size, and then "pick" out the old threads and
retap the hole, but most often we just drilled it to the tap drill
size for a Keensert or helicoil.
All of this was in steel, SS, brass, aluminum, titanium, etc. base
metal castings/assemblies.
But Shred's broken screw is in a piece of plastic. And I'm pretty sure
Shred does not have a complete precision machine shop at his
disposal.
So, if you want to make a small problem, into a big problem, get out
your 1/4' drill motor, install a 1/8" drill bit, and watch it wander
over into the plastic, before you've even gotten started. Then figure
out how to get it back to the exact center of the screw, and watch it
work harden as soon as chips begin to form.
Can I come and watch?
Oh, and as for the left handed ("reverse cut") drill bit, try to find
one that small.
Then hope that the bit welds itself to the stub of the screw as this
thread form (PT) is specifically designed
not to loosen or back out of plastics very easily.
Hope this helps,
sail...@mindspring.com
> On May 10, 3:38 pm, outdrsmn <ccy...@hotmail.com> wrote:
>
> > Shred,
> > A reverse cut drill bit and an easyout should remove the screw shank.
> > A lot of times the reverse bit will actually be enough to start
> > backing the screw shank out on is own. Just use a battery operated
> > drill with good torque and go slow, you don't want to build up any
> > heat. You can even run some water over it to keep it cool. If you
> > hand tighened it then the likely cause of failure is an isolated
> > manufacturing defect. The smallest imperfetion or slight contamination
> > of the steel can cause a failure. Plus stainless isn't as strong as
> > most people think, it mainly has good corrosion and vibration
> > resistance.
>
> hey great tip outdrsmn!! i went looking for such tools and found a 2-
> that's the kind of tool you were talking about, yes? maybe use a pair
> of vice-grips for the extraction step since i doubt you'd want to do
> that part with the drill. anyway, for shred's board, this $12 tool
> might be worth a shot before paying a *lot* more to have the insert
> replaced by a board repair expert. good tip about running water over
> it while drilling too.
>
> p.s. i wasn't able to find any reverse cut drill bits available
> separately. custom-cut tooling perhaps?
Great Idea here, EXCEPT......
The smallest of these "left hand drill/easy out type extractors" from
the catalogue is 1/8" dia.
Think you can get a 1/8" drill started right in the middle of a ).146"
broken screw?
I want to watch....!
On Dan's idea to use a Dremel cut off wheel to make a slot for a flat
tip screwdriver in the top of the
broken off screw stub, that could work....EXCEPT....
How do you get the Dremel wheel right on center of the broken screw,
and if the screw is broken off
flush with the surface of the plastic insert, how much do you want the
wheel to "slot" the surrounding plastic?
The outside dia. of the screw is 6 mm (0.236"), but this is not a
standard thread. It's a special rolled or stamped
30 deg. thread form where the minor dia. of the thread is 3.8 mm (I
just measured one).
That's only 0.146".
If it was a steel screw, you could put acid down the hole and eat up
the screw stub, but it's SS so no glory there
either.
Hope this helps,
Dan Weiss
<sailq...@mindspring.com> wrote:
> On May 10, 4:18 pm, grayson <grayson.k...@gmail.com> wrote:
>
>
>
>
>
> > On May 10, 3:38 pm, outdrsmn <ccy...@hotmail.com> wrote:
>
> > > Shred,
> > > A reverse cut drill bit and an easyout should remove the screw shank.
> > > A lot of times the reverse bit will actually be enough to start
> > > backing the screw shank out on is own. Just use a battery operated
> > > drill with good torque and go slow, you don't want to build up any
> > > heat. You can even run some water over it to keep it cool. If you
> > > hand tighened it then the likely cause of failure is an isolated
> > > manufacturing defect. The smallest imperfetion or slight contamination
> > > of the steel can cause a failure. Plus stainless isn't as strong as
> > > most people think, it mainly has good corrosion and vibration
> > > resistance.
>
> > hey great tip outdrsmn!! i went looking for such tools and found a 2-
>
> - Show quoted text -
Fair point Roger regarding the difficulty of cutting a slot in a
snapped (possibly with a sharp "crown") screw that sits flat with the
top of the insert. It was not that tough to flatten to broken screw
with enough clearance. I used this method on an Mid-90s Mistral and
determined it more efficient to damage top of the plastic insert -used
to secure the anti-twist device- and get to the screw than to loose
TOTW replacing the entire insert. Ultimate precision is not necessary,
only enough to get the job done with an acceptable level of cosmetic
damage.
I completely agree with you that replacement of the entire insert is
the most comprehensive approach, but most sailors aren't comfortable
removing and replacing a footstrap insert -I'd guess especially so on
a production board- and a professional repair costs a few pennies and
lost TOTW.
I think each situation must be addressed for its unique aspects while
considering several of the suggestions here. Your technical knowledge
is not to be dismissed, of course.
-Dan
outdrsmn
> - Show quoted text -
I'm not trying to tell anyone to do something that I haven't already
done, Granted I do have some pretty small drill bits and and
extractors that I got from a retired machinst. I don't claim to be a
certified mechanic or machinest but there are very few things I can't
fix. I spent quite a lot of time around aircraft and automotive
mechanics so I know a little about problems that can be encountered
with fasteners and how to remove stuck or broken ones. I mean no
disrespect as your experience far exceedes mine but what harm can come
from trying if you understand the consequinces.
I figured I had three choices, A... ignore it. B.... try to remove
the screw. C.... replace the insert. If I failed at B then I could
always resort to A or C and if worst case the drill slipped and
punctured the board then it would be easy to repair when the insert
was replaced.
In my case maybe I was just lucky or maybe I had a different type of
fastener but I was able to do it. I used a cordless drill, the
smallest drill bit I have, something on the order of 1/32 and a larger
left hand cut bit. I didn't have to punch the shank because when the
screw broke it left a depression so having the bit wander wasn't an
issue. Even so I was prepared to either dimple it with an engraving
tool or die grind a depression with a dremel tool. I wasn't going to
punch it because the force could have loosened the insert or broken it
out completely. I slowly drilled the small pilot hole first then used
the left hand bit on the low speed high torque setting on the cordless
drill the bit made about a couple cutting revolutions then got caught
in the metal as I had hoped would happen. I lightly worked the trigger
on the drill and started the screw shank turning out of the board.
Had it not caught I would have continued cutting the larger hole and
finished the job with the extractor.
Dan's method would work too. You will have some collateral damage to
the insert and heat will be a problem, water might mitigate that.
Just don't use a corded tools as we all know water and electricity
aren't the best of friends.
C
wind.sh@dow
wrote:
>I don't doubt sailquik's knowledge or advice, but wonder just how many
>people that sail way more than most of us go to the effort to find the
>exact screw they need. I've never needed Tsunami's matchstick trick
>for a footstrap insert, although I've used the trick lots around the
>house. But the straps on at least 2/3 of the 20 or so boards I've
>owned rarely got loose and I'd be amazed if they all had the stock
>screws.
<snip>
On 10 May 2007 16:21:44 -0700, Dan Weiss <dwu...@comcast.net> wrote:
>Fair point Roger regarding the difficulty of cutting a slot in a
>snapped (possibly with a sharp "crown") screw that sits flat with the
>top of the insert. It was not that tough to flatten to broken screw
>with enough clearance. I used this method on an Mid-90s Mistral and
>determined it more efficient to damage top of the plastic insert -used
>to secure the anti-twist device- and get to the screw than to loose
>TOTW replacing the entire insert. Ultimate precision is not necessary,
>only enough to get the job done with an acceptable level of cosmetic
>damage.
<snip>
On May 10, 5:49 pm, "sailq...@mindspring.com"
<sailq...@mindspring.com> wrote:
>> On May 10, 3:38 pm, outdrsmn <ccy...@hotmail.com> wrote:>Hi outdrsmn,
>>
>> Sorry, but this is a bad idea.
>> This is not a 1/4-20 bolt, or even a #6-32 screw thread!
>> The minor dia. of the screw is 3.8 mm (I just measured one with a
>> pretty accurate
>> digital vernier caliper).
>> 3.8 mm is 0.1496 inches.
<snip>
On 11 May 2007 09:28:35 -0700, outdrsmn <ccy...@hotmail.com> wrote:
>I'm not trying to tell anyone to do something that I haven't already
>done, Granted I do have some pretty small drill bits and and
>extractors that I got from a retired machinst. I don't claim to be a
>certified mechanic or machinest but there are very few things I can't
>fix.
<snip>
So what we have is this: Roger, who is obviously very qualified and
knowledgeable, vs. people who needed and found other solutions.
According to Roger, this is in fact rocket science, but there are many
people who do not want to try replacing an insert, have nobody within
500 miles to hire to do it, and found a workable solution. One has to
wonder if a workable solution isn't good enough sometime. Most farmers
would definitely say it is.