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Removing a grub screw

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Harry Wilkes15/04/2019 14:48:00
1343 forum posts
65 photos

I'm just thinking ahead statrted to put my 3" Burrell gearing back togather only to find one of the sprockets as a grub screw stuck in it and the allen hex is rounded ! It looks as if it's 2BA with a 5/64 allen key at this point I have given it a good dose of penetrating oil hoping come tomorrow it will screw out if not would welcome suggestions as to how to remove it my first thought is some heat,


J Hancock15/04/2019 15:04:21
836 forum posts

You may be lucky but my guess is, it will be easier to drill right through it and use an ' Easyout '.

Brian Oldford15/04/2019 16:07:33
686 forum posts
18 photos

"Easyouts". . . . . .Invention of Satan.

Swarf, Mostly!15/04/2019 16:11:59
668 forum posts
73 photos

Hi there, Harry,

I agree with Brian about 'EasyOuts' - they can expand the bolt and make things worse.

My preferred method is to use a left-hand drill. It will centre well enough in your socket grub screw and, eventually, bite and wind out the screw.

I believe there are a few videos on YouTube.

As well as the simple left-hand twist drill, you can get a screw remover that has the same shaped tip.

Best regards,

Swarf, Mostly!

Nigel Bennett15/04/2019 17:28:12
456 forum posts
20 photos

One method I've sometimes used with success is to batter in a Torx bit - it needs to be a tiny bit bigger than the hex socket, but not so much it swells the screw and binds it more tightly. The action of battering it in helps to loosen the grub screw, and then hopefully there's enough grip to unscrew it.

Former Member15/04/2019 17:40:43
1329 forum posts

[This posting has been removed]

Harry Wilkes15/04/2019 18:06:26
1343 forum posts
65 photos

Agreed Brian

Swarf would have to fit it in the 4 jaw chuck to drill left hand

Nigel that thought have crossed my mind

34046 again that thought have crossed my mind

Thanks to all for replies


Mikelkie15/04/2019 18:07:23
129 forum posts
13 photos
Posted by Brian Oldford on 15/04/2019 16:07:33:

"Easyouts". . . . . .Invention of Satan.

I agree

mick H15/04/2019 18:32:40
766 forum posts
28 photos

The last time I was stuck like this I drilled out the centre of the grub with a carbide drill and the resulting "cylinder" with the threads came out easily with a tight fitting screwdriver.


Martin Connelly15/04/2019 18:33:10
2137 forum posts
222 photos

If it is in a through hole then a right hand drill may catch and drive it out of the hub.

Martin C

Clive Foster15/04/2019 18:44:41
3135 forum posts
109 photos

There are Easi-Outs and proper extractors!

The conical left hand thread, uber hard, screw in until it (usually) breaks breed are indeed a monument to the creativity of Beezlbub and his minions in devising ways to frustrate humanity.

The drive in splined shaft variety on the other hand do generally work as the hole is sized so that the splines displace material from the seized bolt around the main shaft to give the tool something to grip on rather than expanding the remains of the broken bolt more tightly into the threaded hole. Basically the professional, sorted, version of batter in a Torx bit, cut off allen key, file tang or whatever is this weeks favourite thing with sharp edges.

I got Numbers 1 to 5 of the original breed made by Ridgid tools from the Snap On man longer ago than I care to admit. Very much not cheap then but effective. See **LINK** for the current UK source. The basic extractor sets sans drills, guides and snazzy box are, I think, quite affordable. Its nice that you can buy them individually should you break one. I'm on my third No 1 (the teeny one) and second No 2.

These days Snap-On sell their own BluePoint brand sets, even more not cheap, and there are various less expensive knock-offs. Some no-name imports, probably of "are you feeling lucky" quality judging by the price, others from respected brands such as Sykes Pickavant. I'm periodically tempted to get the cheapest set I can find for the box, drills and guides but having managed just fine without box, guides or dedicated drills for "mumble-mumble" years splashing out on extractor numbers 6, 7 and (maybe) 8 is more likely. No 8 is serious money but it is a big brute needing a 16 mm Ø hole. If you need the No 8 you are likely snorkel deep in the kitty litter!


bill ellis15/04/2019 18:57:55
71 forum posts
2 photos

I've had luck in the past using a sliver of very thin feeler gauge down the side of the allen key. Put the sliver in first against one of the flats (or nearly flat if it is really rounded out) then tap the key in along side. It takes up enough room to allow the key some purchase. Good luck.

not done it yet15/04/2019 19:23:23
6810 forum posts
20 photos
Posted by Mikelkie on 15/04/2019 18:07:23:
Posted by Brian Oldford on 15/04/2019 16:07:33:

"Easyouts". . . . . .Invention of Satan.

I agree

Not all, but likely about 90% of them! Only the very best quality are reliable!

I use left handed drills if possible.

I.M. OUTAHERE15/04/2019 21:38:13
1468 forum posts
3 photos

Before drilling or doing anything drastic you could try inserting a suitable pin punch into the hex hole and give it wrap with a hammer - don’t belt it to death just a sharp wrap , this can relieve the pressure on the grub screw.. I have also drilled most of the way through and used a piece of steel rod that has been turned down to fit into the hole and held it in place with high strength retaining fluid ( loctite) , let it dry for a day and give the rod a twist with a pair of vise grips .

Nicholas Farr15/04/2019 22:58:24
3360 forum posts
1542 photos

Hi, the danger of drilling a hole through a hex grub screws and then basing something in, is that they are prone to split. A split grub screw is just about impossible to unscrew because whatever you use in the hole will just open it out and wedge it into the hole. XD 351 idea of drilling and Loctite (or equivalent) a rod or a sacrificial hex key is a good approach, providing you don't get any of it in the threads.

Regards Nick.

Hopper16/04/2019 03:56:25
6397 forum posts
334 photos

Sometimes a dab of coarse valve grinding paste on allen key is enough to make it grip. Grinding off the worn end of the key helps too.

Otherwise a left hand drill bit is my go-to solution. Drill close to the thread root diameter and the shell usually spins out before drilling  is complete.

Edited By Hopper on 16/04/2019 04:04:43

Ian S C16/04/2019 11:39:35
7468 forum posts
230 photos

There is a compound available, come in tiny bottle and I think it is diamond grit. Trouble with grub screws, they are hard. The pin punch idea is what I would use, give it a tap, then rock the screw back and forth, the repeat, take the easiest way, either in or out, just take your time it should come out.

Ian S C

I.M. OUTAHERE16/04/2019 12:08:00
1468 forum posts
3 photos

Hope like hell it isn’t an unbrako - that usually means using carbide tooling !

norman royds 216/04/2019 12:47:01
48 forum posts

method I used in the past is to find a small threaded bolt about the same size as allen key and tap into the hole not to hard and gently tune it out used to work on old motor bikes allen screws regards norm

Mick Henshall16/04/2019 13:59:26
561 forum posts
34 photos

So spend money on lefthand drills in case you need to get broken something out of a hole, what else are LH drills good for?

Mick 🇬🇧

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