How to remove set screws?

[Tim Kearsley]

Hi all,

 

I've got into a bit of a mess with some Lado electric retracts!  The U/C leg is retained in the retract by two set screws, each of which requires a small Allen key to turn it.  Unfortunately, I seem to have mangled the heads to the point where a key simply slips round inside it.  The situation isn't helped by the fact that I think I went OTT with the Loctite on the threads and the screws are VERY tight now!

 

So, you chaps who are much more savvy with engineering than I am, what are my options?  Am I stuck with drilling out the jammed screws and replacing with new?

 

Thanks for any advice.

 

Cheers,

 

Tim.

[Pete B]

1. Before anything else, heat the head of the screw with a small soldering iron - that should release the thread lock.

2. Try a slightly larger Allen key, ie, if it's a 1.5mm, a 1/16" (or 1.6mm) key may give you enough purchase.

3. If you can get a Dremel saw-blade to it, cut a slot in the head and use a bladed screwdriver - that's a winner if you have access.

 

It's a common problem for the heli boys and the above is the normal advice offered - works for me!

Pete

[Tim Kearsley]

Hi Pete,

 

Thanks for that.  I didn't realise that heat would help with the Loctite issue.  Unfortunately, I can't get at the screw-head, as it's beneath the surface of the body of the retract, so can't form a slot in it.  However, if I can ease the Loctite a bit, I MIGHT be able to get enough purchase with a key.

 

Thanks.

 

Tim.

[Colin Naylar]

Tim, are you sure it is the screwheads that are mangled and not the Allen Key? I have sometimes got over this problem by cutting off a few millimeters off the Allen Key where it has been rounded, and thereby having a brand new key that fits.

[Steve Hargreaves - Moderator]

Some heat will make all the difference Tim...it really softens the threadlok...get it as hot as you can but make sure you don't melt anything plastic in the vicinity....

 

A very good tip from Colin as the ends of small allen keys get a bit mangled very quickly.....a cut off wheel in a dremel or similar will soon do the job...try & keep the end as square as possible & try & keep it cool...too much heat will destroy the temper of the metal & leave it with the consistancy of toffee.

 

Another tip is to try an imperial allen key (assuming the set screw is metric) 1/16" is about 1.6mm 3/32" is about 2.6mm 1/8" is about 3.2mm...might just be the right size to ease into the set screw & allow you to turn it.

 

Replacement setscrews available from modelfixings.

 

Just another thought too....many of the RC products coming out of China actually use American (ie imperial) sized fixings....are you sure that the allen keys you are using are actually the right size for the job as metric allen keys may well fit imperial set screws & turn them but as soon as you apply any force they slip because they are slightly too small (see above!!)

 

Good luck & remember always apply equal amounts of intelligence & brute force

[Tim Kearsley]

Hi Colin,

 

Yes, I know exactly what you mean!  I suspect I've actually got a bit of both going on here.  I know some of my Allen keys are not of decent quality and have become rounded.  Inspection of the screw-heads does make me think that the sockets have too become a bit rounded though.  I've used your trick before to give myself a nice, new key and I guess it would be worth trying that again.

 

Thanks.

 

Tim.

[Tim Kearsley]

Hi Steve,

 

All points noted and I'm sure the metric/imperial issue has had an effect here.  Trouble is, my Allen keys are all loose in a box and are mixed metric/imperial.  I think the heat trick will be significant as the Loctite is really jamming the screws up quite solidly.

 

I can completely agree with using Modelfixings for new items - I've dealt with them quite a bit and they are simply superb and EXTREMELY fast!  I hasten to add that I have NO connection with Modelfixings, other than as a highly satisfied customer!

 

Cheers,

 

Tim.

 

[Martin Harris - Moderator]

A left handed drill will often remove screws in this sort of situation (this technique is often used to remove sheared studs - Google left hand drills).

 

The heat created while drilling, coupled with vibration will often shift a stuck screw.  Even if this doesn't work it may be possible to drive a larger Allen key into the hole you just drilled.

Edited By Martin Harris on 09/07/2010 10:08:33

[Steve Hargreaves - Moderator]

My worry always when trying to drill out a screw (especially at these small sizes) is that the drill snaps & you then have a hole with a very hard piece of HSS in it......usually game over...

[Martin Harris - Moderator]

Been there, sent the postcards...you would need to be very careful!

[Erfolg]

I have wondered about the suitability of small soc screws for modelling use.

 

In the dim distant days when the UK had an engineering industry and all these types of fixings used high quality alloy steel, by brands such as Unbrako. Problems were not unknown with small size grub screws and countersunk heads.

 

Now that the quality of all socket head screws is questionable dependant on source, greater care is need to ensure that fastener is compatible with its expected duty, particularly with smaller sizes.

 

The situation is compounded by many of the hexagon keys are also of doubtful quality. The corners rounding of after the application of lightest forces.

 

I guess the physical size with lighter weight, visually attractiveness of these screws make them most attractive to all. That is excepting problems such as outlined.

[Martin Harris - Moderator]

I would certainly recommend buying a set of good quality branded hexagon keys in both metric and imperial from an engineering tools supplier.  I'd also beware of grinding the ends off as I don't believe they are hard throughout their length - I remember an advert for pukka "Allen" keys that claimed (IIRC) you could twist them 2 1/2 times before they would shear...

 

I'm sure that the majority of problems are from the belief that all socket screws are metric - as previous posters have pointed out, many ARTFs and accessories are aimed at the American market.

 

I always assess the fit of a hexagon key before applying any pressure and if in any doubt, try the nearest size up from the alternative system.  If there's any hint of wear or damage to the socket, don't refit the screw - replace it!

[kc]

I would have thought a drop of cellulose thinners might soften the locktite if there is nothing plastic around to harm

There are things called " Easy Outs " which have a coarse left hand 'threaded'  screw which can remove stubborn screws.  Usually one drills a pilot hole but that wont work in a hardened bolt but the Easy Out might catch in a mangled socket head.  They are just the thing for removing broken plastic wing bolts too, so they will not be wasted!  Fairly cheap now in sets from engineering suppliers.  You really need a chuck type tap holder too for them.

 

To remove screws such as woodscrews in door hinges etc a sharp tap with a hammer and nail punch works wonders.  Impact in the rotating direction might work on the allen screw once an allen key is jammed in the socket.  Beware of the key flying out and damging the model etc!

Edited By kc on 09/07/2010 12:20:05

[Tim Mackey]

You have loads of excellent advice their Tim - I can add nothing except fully endorsing the heat thing - it really does work wonders on the loctite which as you now know, works far too well"

[Erfolg]

The problem of quality is difficult for the shopper to address.

 

Looking at the screws tells you little, as they really do look very similar.

 

This is the one time where a lot of store can be placed on Brand Names. Yet we modellers buy in plastic packets, with scant information regarding specification, beyond size. The days where boxes of Holochrome, UnBrako have long gone in many parts of the country.

 

Screwfix appear to be a source, where a quality can be assured, dependant on specification. Unfortunately they seldom stock the sizes modellers want.

[Steve Hargreaves - Moderator]

Timbo, maybe move the whole thread to the Hints & Tips section & make it a sticky......

 

I bet many modellers have this problem.....

[Tim Kearsley]

I must just say a big "thank you" to all of you who have replied to my plea - just goes to prove again what a great resource this forum - and web site - is.

 

Cheers, chaps.  I'll get me soldering iron out this evening.....

 

Tim.

[Tim Mackey]

Make sure you use decent wattage iron Tim, as the screw and surrounding material wil soon sap away any heat.  Thread moved as suggested Steve

[Myron Beaumont]

An Allen key type head will normally be of hardened steel (forget drilling and left handed extractors )-However with a riffler file you can make a flat on the circumference so that a purchase is available for pliers / mole wrench /tiny open- ended spanner.. This is as I know where it is useful to have a workshop full of things "you might need ". It takes a life time to collect these bits & bobs  You might even be able to bang onto it a small socket or epoxy your allen key into the hole ? preferably with metal filings added

Myron

NE1 ex RR engineer  !

Edited By Myron Beaumont on 09/07/2010 16:39:55

Edited By Myron Beaumont on 09/07/2010 16:40:57

Edited By Myron Beaumont on 09/07/2010 16:42:10

[Martin Harris - Moderator]

Maybe the case with Unbrako or HoloKrome but the average screws used on models cut easily with a hacksaw - it may be that the socket area is harder although I doubt it.

 

I'm assuming Tim's problems relate to grub screws? This reduces the options rather if it's the case.

Edited By Martin Harris on 09/07/2010 17:08:51

[Martin Harris - Moderator]

Another non-destructive approach might be to get hold of some of this in conjunction with a new key if the socket isn't too far gone  - I've used it in the past for similar jobs and it does give considerable extra purchase.  Not cheap, but a bottle would probably last a lifetime...mine was in a little tube so it might be worth hunting around...

[Tim Mackey]

Posted by Myron Beaumont on 09/07/2010 16:38:43:

An Allen key type head will normally be of hardened steel (forget drilling and left handed extractors )-However with a riffler file you can make a flat on the circumference so that a purchase is available for pliers / mole wrench /tiny open- ended spanner.. This is as I know where it is useful to have a workshop full of things "you might need ". It takes a life time to collect these bits & bobs  You might even be able to bang onto it a small socket or epoxy your allen key into the hole ? preferably with metal filings added

Myron

NE1 ex RR engineer  !

Edited By Myron Beaumont on 09/07/2010 16:39:55

Edited By Myron Beaumont on 09/07/2010 16:40:57

Edited By Myron Beaumont on 09/07/2010 16:42:10

 

If my experience with retracts is anything to go by, then I think you will find that the set screw is "set" below the surface of the surrounding area and therefore inaccessible for this type of procedure. Itsalso my bet that the reason it rounded in the first place was an incorrect size of allen key - probably metric versus imperial socket.

[Erfolg]

Myron is absolutely correct, the Unbrako and HoloKrome used +60 ton steel (against approx 32 ton of normal steel), plus they were alloyed. A consequence of alloying was that the screws were difficult to saw, best done slowly, with medium pressure with a new blade.

 

These socket heads were incredibly durable, wear resistant etc.

 

There was a time that the UK did produce the best, although in this case not the cheapest.

 

The idea of adhering the screw to the key has a long tradition, although welding would be the method (bigger bolts).

 

One method that will work, if the screws are low quality, is that of drilling out to root dia. It does require a level of skill and care, that a non tradesman may not have.

 

If the method employed (whichever one ) damages the thread, run a plug or third tap down to clean the thread up. I guess the option of going up by a size is limited, if the damage is more than tolerable, as I suspect the size will be 2 or 2.5mm dia.

 

In the good old days of BA threads the range was huge with very small incremental steps between sizes. Can still be a non standard solution in even these days.

 

Erfolg

[Myron Beaumont]

Timbo

Yep,Point taken! I'm not familiar with retracts so I was just giving out advice for normal applications to a problem that most mechanics come across daily . ie Exhaust systems badly corroded,broken off studs  etc etc

PS Will swap my travelling hangar (camper van ) for your kit car  There is a fridge in it too  that will hold dozens of sticky buns .

[Tim Mackey]

OK its a deal, as long as the fridge is pre-stocked with £5000