Brass Hex Socket Set Screws

I’m wondering if I can use these for holding HSS tool shafts in an alloy bush rather than using steel screws with a brass insert. Huge difference in price as far as I can see, just wondering how durable the brass screws are likely to be. Any thoughts? The screws I’ve seen on the auction site are cup point. TIA.

Not my field of expertise, but I would have thought Brass and Alloy, I take it you mean aluminium alloy, would not be happy bedfellows due to electrolytic action.

I would think the durability of the hex socket in brass would be a weak point. To get the best of both worlds must be a brass insert, modifying a standard hex screw is not difficult but would it really be worth the effort?

Mike

Why would you need to use a brass insert against a HSS tool steel shaft as a cap screw wouldn't mark it?

David

Vic,

If you are using decent HSS ... What is the problem with steel screws ?

Perhaps I have lived a sheltered life, but I don't think I have ever seen a HSS tool bruised by a screw [and I've seen plenty of 'mushroomed' screws].

MichaelG.

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Edit: Just realised that you may be using inserts of HSS in a softer shank.

Edit: My post crossed with David's

Edited By Michael Gilligan on 20/01/2019 22:48:16

Edited By Michael Gilligan on 20/01/2019 22:49:07

I was taught to use a soft packing between the screw and toolbit but when I have not done so I have not yet broken the tool bit but maybe the day will come.

Mike

Well, I've been clamping HSS and tipped tools with carbon steel shanks using plain steel screws for 20 years with no ill effects.

Neil

Obviously Neil but what I’m clamping are round section tools into a bushing. Any burrs thrown up will impede removal of the tool. Admittedly I haven’t yet tried clamping HSS but a commercial version which does uses set screws with a brass insert to avoid such problems so I assumed it was a good idea.

Assuming you are using HSS toolbits these will not mark or burr when secured by socked head grub screws,should you be using hss steel butt welded to tough but unhardened shanks then steel grub screws will burr the shank,brass screws would be suitable for this securing method, one way would be to make up short lengths of round bronze which would be a push fit in the tapped hole and then insert hard steel skt head screws,so that the bronze is sandwiched between the tool and the screw.

For solidity, I'd be more inclined to use a conventional grub screw but if there's any question of raising a burr I'd grind a small flat on the HSS insert for the grub screw to bear on.

I think the idea of a soft packing or screw tip is not to prevent the marking of the toolbit but to avoid a very small contact area on a very hard tool. I think some of the screws in tool holders are rather harder than Allen screws which many people use. They often had a very hard dog point which ham fisted apprentices will probably tighten with all their strength.

Mike

Just wondering if brass slugs might get compressed by steel set screws and end up jammed in the hole? Might be more of a problem in practice than burring of the HSS.

Even mild steel screw tips can mushroom and then stubbornly refuse to unscrew out of the tool holder. Brass is somewhat softer and as John says, squashing might be a real problem.

I think the dog point screws are an attempt to combat the tip spread and ensure that unless extremely mushroomed will unscrew without damaging the thread. Interspersing a soft packing should protect the hard toolbit from a high point load and the screw from mushrooming.

Mike

George Thomas was keen on copper slugs at the bottom of the threaded fixing hole. Turn the slug to just clear the thread. Poke it down the hole with the tool bit inserted an expand the slug slightly using a parallel punch down the hole. This will stop the slug falling out when the tool bit is removed. Back the whole thing up with a normal steel cap head as usual.

regards Martin

Though I see you can buy grub/set screws with hex sockets I would be very chary about applying much torque - I think the socket would easily strip.

I think that might depend on the size of grub screw in question. I've replaced some of the Allen screws in a few of my Dickson QCTP holders for grub screws (M5) and they seem fine. They don't generally see much action once the tool is in place so they're not being done/undone on a regular basis.

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... and, very importantly, the general quality and manufacturing tolerances of the screw and the wrench/key.

MichaelG.