Locktite allowance

[Michael GilliganParticipant @michaelgilligan61133]

For general reference … It may be worth repeating this, from a post a couple o& years ago:

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: __ The standard ‘Pin and Collar’ test is briefly described here:

SORRY … that link is dead 

The ISO and ASTM standards are technically similar, but ISO uses Metric units

..

MichaelG.

Edited By Michael Gilligan on 23/08/2023 11:45:04

[Michael GilliganParticipant @michaelgilligan61133]

For anyone really interested, here is a 188 page PhD thesis

**LINK** https://core.ac.uk/download/pdf/144148736.pdf

MichaelG.

[old martParticipant @oldmart]

I would go for 0.05mm and not too fine a finish on the mating surfaces. Some grades tolerate contamination but as clean and degreased as you can achieve in two or more stages will give the best strength.

[Dave HalfordParticipant @davehalford22513]

Strength is also dependant on the area of the joint. Sometimes there just isn’t enough contact area.

[Emgee]

On Emgee Said:

Have 601 and 638, which will be best for 6mm diam pin in a 3mm deep blind hole CZ121 brass/brass joint ?

Emgee

Emgee’s requirement, simply stated as a deep blind hole, doesn’t give enough information, to differentiate between 601 and 638.  Both are intended for joining cylindrical parts.

601 is low viscosity, can bridge a small gap, and takes a while to set.  It’s able to flow over surfaces, bridge small imperfections, and gives the operator some fiddle time – glues that grab are a right pain if any adjustments are needed!  This is probably what Emgee needs.

638 is fast setting and thicker, so harder to apply evenly, very little fiddle time, and it can’t bridge imperfections.  It’s advantages are fast setting, which speeds up jobs that don’t have to be carefully aligned, a bit stronger than 601, and it resists shock loads and vibration.  Best of all it doesn’t mind oil in the joint, and can take more heat.  This combination suggests 638 is better for automotive work than 601.

For home-workshop use, either will do. Noting Michael’s caveat about allowing room for excess liquid to escape when the pin is inserted, I vote 601, but I’d use 638 if that’s all I had.   Confession time, just securing pins in holes for ordinary purposes, I mainly use Super-glue.  Not as strong or heat resistant as a Loctite or other professional fastener.    When using super-glue the joint has to be proper clean, and the glue fresh.  Once opened, super-glue seems to quickly lose strength. As far as I can tell Pound Shop and expensive Brand-name super-glue should both be used asap.

Dave

 

[Neil WyattModerator @neilwyatt]

This has been gone over many times in the past. A very small clearance is strongest, a close push fit or a force fit is ideal.

Note that:

1. the adhesive lubricates and aids assembly
2. the adhesive works by filling in any micro roughness
3.  The fit can’t be too close, you don’t actually need to leave any allowance at all.

[Michael GilliganParticipant @michaelgilligan61133]

Reference your #3, Neil

Given that the question was about putting a pin in a blind hole … Dave was gracious enough to state:

… Noting Michael’s caveat about allowing room for excess liquid to escape when the pin is inserted …

MichaelG.

[Michael Gilligan]

On Michael Gilligan Said:

Reference your #3, Neil

Given that the question was about putting a pin in a blind hole … Dave was gracious enough to state:

… Noting Michael’s caveat about allowing room for excess liquid to escape when the pin is inserted …

MichaelG.

Better to groove the pin to allow air to escape than to have it a loose fit. I believe this is industry practice.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Like wot I wrote  🙂

MichaelG.

[noel shelleyParticipant @noelshelley55608]

I doubt it applies to loctite but for supa glue keep it in the fridge and it will keep for quite a while ! Noel.

[martin haysom]

On martin haysom Said:

read the spec ,do what it says ,work’s every time. must remember to do this myself. used a Loktite recently [ not at home so can’t check which one] spec says sets in 1/2 hour but full strength one week

I used the 638, should have said the pins are drilled through 1mm diam so air can escape on assembly. Finished pins shown here with a screw cap fitted.

Emgee

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