I need to take the slop out of a couple Delrin devices that are subjest to
vibration. They are a bit loose in the hole they fits into. A nylon set
screw threaded into a hole tapped into the Delrin would do the trick, but
it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it & be
done. I've seen spectacular failures with regular Locktite getting near
some plastics. They do make a special version for plastic parts, but
McMaster wants almost $20 for a bottle that will spoil long before I use
more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock against
each other, but adjusting them will be tricky unless I bore all the way
though and can adjust the locking screw from the far side. I can try to
thread the holes _just_ deep enough to hold the screws at the right height,
but if I overshoot, I'm stuck with Plan A.

Any ideas or suggestions?

Doug White

Doug White wrote:
I need to take the slop out of a couple Delrin devices that are subjest to
vibration. They are a bit loose in the hole they fits into. A nylon set
screw threaded into a hole tapped into the Delrin would do the trick, but
it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it & be
done. I've seen spectacular failures with regular Locktite getting near
some plastics. They do make a special version for plastic parts, but
McMaster wants almost $20 for a bottle that will spoil long before I use
more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock against
each other, but adjusting them will be tricky unless I bore all the way
though and can adjust the locking screw from the far side. I can try to
thread the holes _just_ deep enough to hold the screws at the right height,
but if I overshoot, I'm stuck with Plan A.

Any ideas or suggestions?

Doug White

How about using the same thing Mauser did on rifles? Add a small lock
screw that has to be removed or turned into position befure the main
screw will turn.

like this:
http://images.turkmauser.com/webpart...ntmagscrew.jpg

--
Steve W.

In article ,
Doug White wrote:

I need to take the slop out of a couple Delrin devices that are subjest to
vibration. They are a bit loose in the hole they fits into. A nylon set
screw threaded into a hole tapped into the Delrin would do the trick, but
it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it & be
done. I've seen spectacular failures with regular Locktite getting near
some plastics. They do make a special version for plastic parts, but
McMaster wants almost $20 for a bottle that will spoil long before I use
more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock against
each other, but adjusting them will be tricky unless I bore all the way
though and can adjust the locking screw from the far side. I can try to
thread the holes _just_ deep enough to hold the screws at the right height,
but if I overshoot, I'm stuck with Plan A.

Any ideas or suggestions?

Drill the hole a bit undersize, and run the screw in without cutting
threads, using the screw to roll its own threads.

Delrin one of the few plastics for which press fits work, according to
the datasheet. The datasheet (or app notes) tells how aggressive one
should be.

Joe Gwinn

"Steve W." wrote in :

http://images.turkmauser.com/webpart...ntmagscrew.jpg

I don't see how that works well for fine adjustment. I want to tweak it so
I have a slip fit with as little play as possible.

Doug White

Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

I need to take the slop out of a couple Delrin devices that are
subjest to vibration. They are a bit loose in the hole they fits
into. A nylon set screw threaded into a hole tapped into the Delrin
would do the trick, but it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it
& be done. I've seen spectacular failures with regular Locktite
getting near some plastics. They do make a special version for
plastic parts, but McMaster wants almost $20 for a bottle that will
spoil long before I use more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock
against each other, but adjusting them will be tricky unless I bore
all the way though and can adjust the locking screw from the far
side. I can try to thread the holes _just_ deep enough to hold the
screws at the right height, but if I overshoot, I'm stuck with Plan
A.

Any ideas or suggestions?

Drill the hole a bit undersize, and run the screw in without cutting
threads, using the screw to roll its own threads.

Delrin one of the few plastics for which press fits work, according to
the datasheet. The datasheet (or app notes) tells how aggressive one
should be.

I couldn't tap the Delrin with a nylon screw, but I could find an
undersized steel screw & make a tight tap. Then I could use the nylon
set screws. It might take a little experimenting, but I think that would
work OK.

Thanks!

Doug White

Doug White wrote in
:

Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

I need to take the slop out of a couple Delrin devices that are
subjest to vibration. They are a bit loose in the hole they fits
into. A nylon set screw threaded into a hole tapped into the Delrin
would do the trick, but it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on
it & be done. I've seen spectacular failures with regular Locktite
getting near some plastics. They do make a special version for
plastic parts, but McMaster wants almost $20 for a bottle that will
spoil long before I use more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock
against each other, but adjusting them will be tricky unless I bore
all the way though and can adjust the locking screw from the far
side. I can try to thread the holes _just_ deep enough to hold the
screws at the right height, but if I overshoot, I'm stuck with Plan
A.

Any ideas or suggestions?

Drill the hole a bit undersize, and run the screw in without cutting
threads, using the screw to roll its own threads.

Delrin one of the few plastics for which press fits work, according
to the datasheet. The datasheet (or app notes) tells how aggressive
one should be.

I couldn't tap the Delrin with a nylon screw, but I could find an
undersized steel screw & make a tight tap. Then I could use the nylon
set screws. It might take a little experimenting, but I think that
would work OK.

It turns out Permatex has a plastic threadlocking compound for ~ $6 on
Amazon, so I'll probably get some of that & possible combine it with the
home made tight tap idea.

Doug White

"Doug White" wrote in message
. ..

I need to take the slop out of a couple Delrin devices that are subjest to
vibration. They are a bit loose in the hole they fits into. A nylon set
screw threaded into a hole tapped into the Delrin would do the trick, but
it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it & be
done. I've seen spectacular failures with regular Locktite getting near
some plastics. They do make a special version for plastic parts, but
McMaster wants almost $20 for a bottle that will spoil long before I use
more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock against
each other, but adjusting them will be tricky unless I bore all the way
though and can adjust the locking screw from the far side. I can try to
thread the holes _just_ deep enough to hold the screws at the right height,
but if I overshoot, I'm stuck with Plan A.

Any ideas or suggestions?

Doug White

Years ago they used CA glue (super glue) on screws in plastic on R/C racing
cars. When I've done it, I assembled without the glue and then applied the
glue to the bolt head and car chassis after assembly. This holds well but
breaks away cleanly with a little screwdriver force.

RogerN

On Sunday, December 9, 2012 7:49:12 PM UTC-6, Doug White wrote:
Doug White wrote in

:



Joseph Gwinn wrote in

:



In article ,

Doug White wrote:



I need to take the slop out of a couple Delrin devices that are

subjest to vibration. They are a bit loose in the hole they fits

into. A nylon set screw threaded into a hole tapped into the Delrin

would do the trick, but it will probably work loose pretty quickly.



It it was metal, with a metal screw, I'd just put some Locktite on

it & be done. I've seen spectacular failures with regular Locktite

getting near some plastics. They do make a special version for

plastic parts, but McMaster wants almost $20 for a bottle that will

spoil long before I use more than 10 drops.



My current thinking is to stack a pair of nylon setscrews to lock

against each other, but adjusting them will be tricky unless I bore

all the way though and can adjust the locking screw from the far

side. I can try to thread the holes _just_ deep enough to hold the

screws at the right height, but if I overshoot, I'm stuck with Plan

A.



Any ideas or suggestions?



Drill the hole a bit undersize, and run the screw in without cutting

threads, using the screw to roll its own threads.



Delrin one of the few plastics for which press fits work, according

to the datasheet. The datasheet (or app notes) tells how aggressive

one should be.



I couldn't tap the Delrin with a nylon screw, but I could find an

undersized steel screw & make a tight tap. Then I could use the nylon

set screws. It might take a little experimenting, but I think that

would work OK.



It turns out Permatex has a plastic threadlocking compound for ~ $6 on

Amazon, so I'll probably get some of that & possible combine it with the

home made tight tap idea.



Doug White

You can also use thread locking helicoil inserts.

On Sun, 09 Dec 2012 22:35:44 GMT, Doug White
wrote:

I need to take the slop out of a couple Delrin devices that are subjest to
vibration. They are a bit loose in the hole they fits into. A nylon set
screw threaded into a hole tapped into the Delrin would do the trick, but
it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it & be
done. I've seen spectacular failures with regular Locktite getting near
some plastics. They do make a special version for plastic parts, but
McMaster wants almost $20 for a bottle that will spoil long before I use
more than 10 drops.

I have a 3 year old bottle of Gorilla Glue that gets used
occasionally. It spends all of it's time in a freezer between the use
times. Store opened epoxy's and glues in a freezer. Take the out just
before you want to use them.

On 2012-12-09, Doug White wrote:
I need to take the slop out of a couple Delrin devices that are subjest to
vibration. They are a bit loose in the hole they fits into. A nylon set
screw threaded into a hole tapped into the Delrin would do the trick, but
it will probably work loose pretty quickly.

[ ... ]

My current thinking is to stack a pair of nylon setscrews to lock against
each other, but adjusting them will be tricky unless I bore all the way
though and can adjust the locking screw from the far side. I can try to
thread the holes _just_ deep enough to hold the screws at the right height,
but if I overshoot, I'm stuck with Plan A.

Any ideas or suggestions?

Threading in Delrin usually produces undersized holes, so they
grip pretty well to start with. See what happens there before going
into extra hold-downs.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 12/9/2012 4:35 PM, Doug White wrote:
I need to take the slop out of a couple Delrin devices that are subjest to
vibration. They are a bit loose in the hole they fits into. A nylon set
screw threaded into a hole tapped into the Delrin would do the trick, but
it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it& be
done. I've seen spectacular failures with regular Locktite getting near
some plastics. They do make a special version for plastic parts, but
McMaster wants almost $20 for a bottle that will spoil long before I use
more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock against
each other, but adjusting them will be tricky unless I bore all the way
though and can adjust the locking screw from the far side. I can try to
thread the holes _just_ deep enough to hold the screws at the right height,
but if I overshoot, I'm stuck with Plan A.

Any ideas or suggestions?

Doug White

But why NOT use Loctite?

Delrin is about as inert as plastics come.

Easy enough to try it ans see.

On 10/12/2012 6:35 AM, Doug White wrote:
I need to take the slop out of a couple Delrin devices that are subjest to
vibration. They are a bit loose in the hole they fits into. A nylon set
screw threaded into a hole tapped into the Delrin would do the trick, but
it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it & be
done. I've seen spectacular failures with regular Locktite getting near
some plastics. They do make a special version for plastic parts, but
McMaster wants almost $20 for a bottle that will spoil long before I use
more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock against
each other, but adjusting them will be tricky unless I bore all the way
though and can adjust the locking screw from the far side. I can try to
thread the holes _just_ deep enough to hold the screws at the right height,
but if I overshoot, I'm stuck with Plan A.

Any ideas or suggestions?

Doug White



Can you slot or slit the part and use a grub screw to expand it to the
size you need?

On Mon, 10 Dec 2012 01:42:38 GMT, Doug White
wrote:

Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

I need to take the slop out of a couple Delrin devices that are
subjest to vibration. They are a bit loose in the hole they fits
into. A nylon set screw threaded into a hole tapped into the Delrin
would do the trick, but it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it
& be done. I've seen spectacular failures with regular Locktite
getting near some plastics. They do make a special version for
plastic parts, but McMaster wants almost $20 for a bottle that will
spoil long before I use more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock
against each other, but adjusting them will be tricky unless I bore
all the way though and can adjust the locking screw from the far
side. I can try to thread the holes _just_ deep enough to hold the
screws at the right height, but if I overshoot, I'm stuck with Plan
A.

Any ideas or suggestions?

Drill the hole a bit undersize, and run the screw in without cutting
threads, using the screw to roll its own threads.

Delrin one of the few plastics for which press fits work, according to
the datasheet. The datasheet (or app notes) tells how aggressive one
should be.

I couldn't tap the Delrin with a nylon screw, but I could find an
undersized steel screw & make a tight tap. Then I could use the nylon
set screws. It might take a little experimenting, but I think that would
work OK.

Thanks!

Doug White
Greetings Doug,
I machine lots of Delrin and Acetron. What Joseph says about rolling
threads is correct. When I'm making parts for a customer that wants a
tight thread I just use a form tap, AKA roll tap, to tap the hole.
Often even a cutting tap will leave threads undersize enough but a
form tap always makes for tight threads.
Eric

In article ,
Doug White wrote:

Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

I need to take the slop out of a couple Delrin devices that are
subjest to vibration. They are a bit loose in the hole they fits
into. A nylon set screw threaded into a hole tapped into the Delrin
would do the trick, but it will probably work loose pretty quickly.

It it was metal, with a metal screw, I'd just put some Locktite on it
& be done. I've seen spectacular failures with regular Locktite
getting near some plastics. They do make a special version for
plastic parts, but McMaster wants almost $20 for a bottle that will
spoil long before I use more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock
against each other, but adjusting them will be tricky unless I bore
all the way though and can adjust the locking screw from the far
side. I can try to thread the holes _just_ deep enough to hold the
screws at the right height, but if I overshoot, I'm stuck with Plan
A.

Any ideas or suggestions?

Drill the hole a bit undersize, and run the screw in without cutting
threads, using the screw to roll its own threads.

Delrin one of the few plastics for which press fits work, according to
the datasheet. The datasheet (or app notes) tells how aggressive one
should be.

I couldn't tap the Delrin with a nylon screw, but I could find an
undersized steel screw & make a tight tap. Then I could use the nylon
set screws. It might take a little experimenting, but I think that would
work OK.

It also occurs to me that a trilobular (thread-rolling) screw might work
well in delrin. After rolling, the plastic will shrink back a bit,
capturing the rounded-triangle shaped screw enough that it won't easily
work loose.

My instinct is that threadlocking compounds like locktite will fail in
delrin, which is very slippery.

Joe Gwinn

Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

I need to take the slop out of a couple Delrin devices that are
subjest to vibration. They are a bit loose in the hole they fits
into. A nylon set screw threaded into a hole tapped into the
Delrin would do the trick, but it will probably work loose pretty
quickly.

It it was metal, with a metal screw, I'd just put some Locktite on
it & be done. I've seen spectacular failures with regular
Locktite getting near some plastics. They do make a special
version for plastic parts, but McMaster wants almost $20 for a
bottle that will spoil long before I use more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock
against each other, but adjusting them will be tricky unless I
bore all the way though and can adjust the locking screw from the
far side. I can try to thread the holes _just_ deep enough to
hold the screws at the right height, but if I overshoot, I'm stuck
with Plan A.

Any ideas or suggestions?

Drill the hole a bit undersize, and run the screw in without
cutting threads, using the screw to roll its own threads.

Delrin one of the few plastics for which press fits work, according
to the datasheet. The datasheet (or app notes) tells how
aggressive one should be.

I couldn't tap the Delrin with a nylon screw, but I could find an
undersized steel screw & make a tight tap. Then I could use the
nylon set screws. It might take a little experimenting, but I think
that would work OK.

It also occurs to me that a trilobular (thread-rolling) screw might
work well in delrin. After rolling, the plastic will shrink back a
bit, capturing the rounded-triangle shaped screw enough that it won't
easily work loose.

My instinct is that threadlocking compounds like locktite will fail in
delrin, which is very slippery.

My original concern was that it would attacke the plastics, either the
Delrin or the nylon screw. I've seen very spectacular failures when
liquid Locktite was used with polycarboante (Lexan).

I'm going to try the thread forming tap approach. Just got a couple taps
off eBay.

Doug White

In article ,
Doug White wrote:

Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

Joseph Gwinn wrote in
:

In article ,
Doug White wrote:

I need to take the slop out of a couple Delrin devices that are
subjest to vibration. They are a bit loose in the hole they fits
into. A nylon set screw threaded into a hole tapped into the
Delrin would do the trick, but it will probably work loose pretty
quickly.

It it was metal, with a metal screw, I'd just put some Locktite on
it & be done. I've seen spectacular failures with regular
Locktite getting near some plastics. They do make a special
version for plastic parts, but McMaster wants almost $20 for a
bottle that will spoil long before I use more than 10 drops.

My current thinking is to stack a pair of nylon setscrews to lock
against each other, but adjusting them will be tricky unless I
bore all the way though and can adjust the locking screw from the
far side. I can try to thread the holes _just_ deep enough to
hold the screws at the right height, but if I overshoot, I'm stuck
with Plan A.

Any ideas or suggestions?

Drill the hole a bit undersize, and run the screw in without
cutting threads, using the screw to roll its own threads.

Delrin one of the few plastics for which press fits work, according
to the datasheet. The datasheet (or app notes) tells how
aggressive one should be.

I couldn't tap the Delrin with a nylon screw, but I could find an
undersized steel screw & make a tight tap. Then I could use the
nylon set screws. It might take a little experimenting, but I think
that would work OK.

It also occurs to me that a trilobular (thread-rolling) screw might
work well in delrin. After rolling, the plastic will shrink back a
bit, capturing the rounded-triangle shaped screw enough that it won't
easily work loose.

My instinct is that threadlocking compounds like locktite will fail in
delrin, which is very slippery.

My original concern was that it would attacke the plastics, either the
Delrin or the nylon screw. I've seen very spectacular failures when
liquid Locktite was used with polycarboante (Lexan).

I'm going to try the thread forming tap approach. Just got a couple taps
off eBay.

If you don't already have it, Du Pont publishes some very good
application notes on how best to use delrin.

Joe Gwinn