Aquadrive screws

[Graham_Wright]

Due to space restrictions, it is not possible to use hexagon headed screws to attach this drive at either end. Cap head screws are supplied. These do not permit the use of ordinary locking tab washers.

Having heard of the consequences of such screws working loose, I would like to devise some means of positively locking them. I am not in favour of Locktite.

The only mechanical method I can think of is to drill transversely through the head of the screws and run a locking wire through the lot.

Anyone improve on this please?

 

[Talulah]

You could also paint a mark on the bolt head/bearing to help identify any movement.
I've fitted various Auquadrives over the years. Only on the first one did I experience the bolts coming adrift shortly after the install. Not had any problems since. Never used loctite on them.

Don't see any problems drilling the heads as you suggest.

 

[vyv_cox]

My Aquadrive has been fitted for many years and the bolts have never loosened. Get them up tight enough, using an extra long Allen key, and they never will.

What's your problem with Loctite? Excellent stuff, widely used in industry. I have never needed it on the Aquadrive but often use it elsewhere.

Cap head screws are hardened, sometimes to quite a high level. You may encounter problems drilling them.

 

[Graham_Wright]

My Aquadrive has been fitted for many years and the bolts have never loosened. Get them up tight enough, using an extra long Allen key, and they never will.

What's your problem with Loctite? Excellent stuff, widely used in industry. I have never needed it on the Aquadrive but often use it elsewhere.

Cap head screws are hardened, sometimes to quite a high level. You may encounter problems drilling them.

We use Loctite on various production components. It can be released if necessary (by heat) but the use of a wire gives an indication if they are working loose.

I have never come across hardened caphead screws (and we use a few thousand a year!). i have just drilled one to prove the point, with an ordinary HSS drill and it was not a problem. That was a steel one. The ones on the Aquadrive are A4 and will be a bit more difficult

 

[vyv_cox]

I have never come across hardened caphead screws (and we use a few thousand a year!). i have just drilled one to prove the point, with an ordinary HSS drill and it was not a problem. That was a steel one. The ones on the Aquadrive are A4 and will be a bit more difficult

Different from mine then. Mine are black (= heat treated) not stainless.

When trying to find suitable standards for DIY hardness testing of anchors I checked quite a few caphead screws. Some were quite hard and would have been difficult to drill.

 

[Graham_Wright]

Different from mine then. Mine are black (= heat treated)

So are mine!

Must be different grades (or different drills!).

 

[vyv_cox]

So are mine!

Must be different grades (or different drills!).

Black A4?

 

[earlybird]

Cap screws are often grade 12.9. Alloy steel, quenched & tempered.
They used to be grade "V" in the old days IIRC. ~80 tons/sq. inch, machining them in a lathe is tough work.

 

[vyv_cox]

Cap screws are often grade 12.9. Alloy steel, quenched & tempered.
They used to be grade "V" in the old days IIRC. ~80 tons/sq. inch, machining them in a lathe is tough work.

Ah, units that mean something! I still think in tons/sq. inch for steel strengths, so convenient. Although I have worked with MPa for many years I would find it difficult to quote a strength in them off the top of my head.

 

[Graham_Wright]

Black A4?

QUOTE;-

I have just drilled one to prove the point, with an ordinary HSS drill and it was not a problem. That was a steel one. The ones on the Aquadrive are A4 and will be a bit more difficult.

 

[vyv_cox]

QUOTE;-

I have just drilled one to prove the point, with an ordinary HSS drill and it was not a problem. That was a steel one. The ones on the Aquadrive are A4 and will be a bit more difficult.

earlier in the thread you said yours were A4. When I said mine were black you said 'so are mine'. I was pointing out that stainless steel AISI 316 is usually shiny.

 

[Graham_Wright]

earlier in the thread you said yours were A4. When I said mine were black you said 'so are mine'. I was pointing out that stainless steel AISI 316 is usually shiny.

Right! ----- The ones on my Aquadrive are A4 and bright (and shiny!).
The ones I have just drilled in the factory are steel and black. I do not anticipate a problem drilling the A4 ones either.

I agree that the steel (black) cap head screws are (a bit) hard because we sometimes have to reduce the head height on fixtures. (We sometimes reduce the head height on fixtures by accident as well!). But they succumb to ordinary machining processes without too much complaint.