friction retard for set screw

F

Froneck

Titanium

Joined

Dec 4, 2010

Location

McClure, PA 17059

• Jan 27, 2022

• #1

I'm making a gauge to measure length of a slot. Have 1/4" stick X .900 stainless steel bar. (SS because I just happen to have a piece 1/4" X 1 X 6")
Purchased spherical point set screws 8-32 (only thread pitch available in #8) Drilled and tapped 8-32 X .8 deep and .096" thru for hex wrench.
Screw moves easy, I would like to stiffen the movement. Thought of hitting the side of the bar over the tapped hole with a punch. Maybe use an end mill and put a hole thru the side enough to remove threads on one side of tapped hole. Re-tap to remove burrs then press in a piece of Nylon or some other plastic.
Any better ideas??

 

gbent

Diamond

Joined

Mar 14, 2005

Location

Kansas

• Jan 27, 2022

• #2

How much adjustment will it receive? A piece of nylon monofilament line through the hole before threading in the set screw may do the job.

 

C

CalG

Diamond

Joined

Dec 30, 2008

Location

Vt USA

• Jan 27, 2022

• #3

The smallest amount of Loc-tite blue will do what you are after.

 

W

Winterfalke

Stainless

Joined

Mar 26, 2011

Location

Huron

• Jan 27, 2022

• #4

A thick pipe dope, or maybe some anti-seize cooked down a little bit to thicken it more would give you a bit of stiction.

 

W

wood2steel

Cast Iron

Joined

May 17, 2013

Location

georgia

• Jan 28, 2022

• #5

Definitely wrap your head around the Loctite products as CalG mentioned; Loctite blue is perfect for that application, and LcT 680/690 Retaining compound covers most everything else in the shop.
Johnny

 

L

LKeithR

Stainless

Joined

Sep 1, 2011

Location

Langley, B.C.

• Jan 28, 2022

• #6

They make self-locking set screws with little nylon inserts in the threads. Would something like that work.
A quick Google search turned up quite a few different styles...

 

F

Froneck

Titanium

Joined

Dec 4, 2010

Location

McClure, PA 17059

• Jan 28, 2022

• #7

Self locking set screw not available with spherical point. Distance travel is about.030" max. However will be repeatedly adjusted for measurement. Small hole to fit hex wrench on other side so larger surface area for Micrometer measurement. Will Loctite allow repeated adjustments? Would have preferred finer thread but only NC was available.

 

Conrad Hoffman

Diamond

Joined

May 10, 2009

Location

Canandaigua, NY, USA

• Jan 28, 2022

• #8

Nyloc screws are available with a spherical point... if you own a lathe!

 

JST

Diamond

Joined

Jun 16, 2001

Location

St Louis

• Jan 28, 2022

• #9

Loc-tite is not very good for that.

But Vibra-tite does exactly what you want.

 

michiganbuck

Diamond

Joined

Jun 28, 2012

Location

Mt Clemens, Michigan 48035

• Jan 28, 2022

• #10

an 8-32 screw will go out length .031 for one full turn, about ,016 in a half-turn, about .008 in a quarter turn. Using a Allen wrench and counting turns you can use a screw like a depth micrometer.

QT: Screw moves easy, I would like to stiffen the movement.

it is a hack way but I have bumped the thread side with a round stock and small whack.

 

beege

Stainless

Joined

May 18, 2007

Location

Massachusetts

• Jan 28, 2022

• #11

Couple of wraps of teflon taape?

 

jim rozen

Diamond

Joined

Feb 26, 2004

Location

peekskill, NY

• Jan 28, 2022

• #12

Suggest a tapped hole that intersects the adjusting screw, and put a nylon screw in the cross-hole.

 

I

in2glamisgirl

Cast Iron

Joined

Jun 20, 2006

Location

Hawthorne, CA USA

• Jan 28, 2022

• #13

A locking Helicoil will have a long life with predictable running torque.

 

L

Labrat

Aluminum

Joined

Apr 20, 2012

Location

Virginia

• Jan 28, 2022

• #14

When I need repeatable friction, I always go with high force / low coefficient of friction. A Nylon plug as you suggested under a spring is probably ideal. Just make sure your spring deflection is several times what you expect to see in wear on your plug.

Another idea might be a jam nut, constrained from turning, sandwiching a wave or belleville spring.

 

C

CarbideBob

Diamond

Joined

Jan 14, 2007

Location

Flushing/Flint, Michigan

• Jan 28, 2022

• #15

The mangle the thread method only works for a few adjustments.
Same with thread fillers of blue or tape. Even the nylon plug guys suffer from limited life.
The only good methods I have encountered are a second screw at 90 degrees with a brass plug or slotting to the hole and using a screw to collapse it clamping on the threads.
The other of course how a micrometer lock works.
Bob

 

R

ratbldr427

Titanium

Joined

Mar 21, 2006

Location

jacksonville,fl.

• Jan 30, 2022

• #16

If you can put a locking screw 90deg as Bob said , then what I do is put the brass tip in the hole and thread it so that it matches the set screw. It takes very little pressure to lock the set screw and won't damage the threads.Using a brass screw would work well.

 

F

Froneck

Titanium

Joined

Dec 4, 2010

Location

McClure, PA 17059

• Feb 2, 2022

• #17

I have used the brass plug in a hole to stop an adjustment screw from turning. Being lazy I didn't want to turn a brass plug to tap drill size for 8-32 so I used a tough plastic. If it were for a critical adjustment screw I would have used brass but all I needed was friction so that when inserting the hex wrench I didn't move the measurement screw.