Prepared by Jim Snowdon Originator Phil Skoyles

Discussion in 'Modelling' started by Phil Skoyles, May 18, 2017.
Note: Posts are numbered as they appeared in the original forum topic thread. Where there are gaps in the sequence, denoted by a double line between successive posts, the thread had gone off topic completely, the missing posts being of no relevance to the thread subject.

1. I am trying to remove the driving wheels on a GWR 63 class loco but they will not budge, the socket head screws have been filled with paint which does not help, I have a good quality Allen key but it looks if there has been an attempt to remove them before, I am trying to save the wheels, has anyone had a similar problem or has a solution, thanks very much,
Phil

2. John Castle, May 18, 2017
I had a problem some time back when my Allen key got worn and slipped, so I filled the key back to get rid of the worn bit so I could undo it, and then I sawed a screw driver cut across the socket hole. No more trouble. John

3. Guy Lamb, May 18, 2017
If that fails or not practicable try a 'grabit' screw remover.
Regards
Guy

4. Pat Buckley, May 18, 2017
Phil, I have had this problem on several occasions and have found that the use of a low wattage soldering iron of no more than 25watts applied carefully to the screw head can cause the screw and the wheel brass centre to expand at different rates thus releasing the bond. This is an old country garage mechanics trick used on all sorts of nuts bolts and seized joints. You must get all the paint off first with a wire brush in a Dremel or glass fibre pen otherwise the fumes will be bad.be careful and do it with the Allen key in the socket and keep pressure on the key till you feel it give! All the best,
Pat.
PS I have done it on Slaters plastic wheels without any damage.

5. Ian Middleditch, May 18, 2017
You may find that the hex socket is rounded as the key tends to slip especially with tight/seized screws. Use a small diameter cutting disk, small one lets you go deeper without damaging the brass insert, in your drill to grind a screwdriver slot in the screw head. You will get much more purchase and the heat generated helps free the screw. Replacement screws available from Slaters and elsewhere. Alternatively swap the 'modified' screw for one on a tender where they are hidden behind the axleboxes!
Ian.

6. Mike Evans, May 18, 2017
If all else fails drill out the countersunk head of the screw being careful not to touch the brass insert in the wheel.
Remove the wheel, and if the law of sod has gone on holiday, there should be a short length of the threaded part of the screw showing which can then be undone.
Hope this helps,
Mike

7. David Atkinson, May 18, 2017
Use a small diameter cutting disk,
Should you not have a small disc a well worn one may have a small enough diameter to just fit into the screw head.
David A

8. Dave Round, May 18, 2017
I have had the same and resorted to gently drilling the screw head until the countersunk area has been relieved. A gentle tap will loosen the screw and with further drilling you can withdraw the wheel set. The screw head normally falls off leaving the shank that can be removed with a pair of pliers. Slaters do replacement screws Regards Dave \\(Shottesford Dave)

9. Paul Copsey, May 18, 2017
I had to do this a couple of weeks ago and I used a left hand drill , as it drills its biting and the heat its generating probably helps . Took about 20 seconds with a drill that fitted into the hex of the screw . You can then cut a slot to reuse the screw or replace it with a new one .
Cheers
Paul

10. Pat Buckley, May 18, 2017
Mike, had to do that a little while ago, put Loctite on the screws to stop them coming undone only to have a pickup fail and then to discovered I had got permanent threadlock not the weakest one and nothing would shift it. Went and got a new 7mm ( I think ) drill and removed the screw head just as you describe .luckily I hadn’t put it on the thread only the countersunk bit. New pickup fitted and new screw put in with the correct grade of Loctite (222).I don’t normally Loctite retaining screws but the set of Slaters wheels I had would not stay locked and I had to Loctite all six driving wheel screws after one came loose and jammed the coupling rod at a fairly high speed on a test track !
Pat.

11. Phil Skoyles, May 18, 2017
Thanks for the advice, this will be the first time I have done this, I have loosened the small nuts holding the coupling and connecting rods, it is difficult to get to the retaining screws behind the cross head, one of these is the one of them that needs attention. Thanks Phil

12. Pat Buckley, May 18, 2017
Phil, take every thing off the wheels remove all rods and anything that will get in the way if not sods law says you will bend or twist something vital. don’t start anything till you have a clear field and get a small plastic container to keep everything in at the back of your workbench so it doesn’t get knocked over ! Get a small block of wood to put under the opposite wheel you are working on and some blocks or bits of foam to support the loco to keep the paint from being marked. I had to do this on a very heavy newly built DJH Peppercorn A2 a very big loco luckily on the rear ns wheel and managed without getting the new painted and lined loco damaged. Let us know how you get on .
Pat.

13. Guy Lamb, May 18, 2017
I would also try in the first instance a cotton bud soaked in a soda paint stripper (Nitromors) to break the paint seal and clean out the socket head, if applied sparingly should be ok. If needs be neutralise with vinegar
Regards
Guy

14. Phil Skoyles, May 18, 2017
Thanks Pat and Guy, I will try the stripper first, I need to buy a spanner for the crank pin nuts which I believe are 12 BA,
I will let you know how I get on.
Thanks
Phil

17. David Hill, May 19, 2017
Where the socket has become worn I have had some luck using a small screwdriver.

18. Bob Thompson May 19, 2017
The Socket headed screws that Slaters use are notorious for being difficult to remove especially if they have been in place for some time.
I believe the older screws were of poor quality Steel and the socket in the head was very shallow, but the later screws are much better.
If I get in this situation I invariably end up drilling them out on a pillar drill using a 2mm drill bit. Be careful to only drill just enough to allow the screw head to be broken off, so as after removing the wheel you should be able to get the remains of the screw out using a small screwdriver or pliers.
Do not be tempted to try and use heat to get the screws out. If you do, the likelihood is that you will distort the inner plastic moulding and the Brass bush will not sit square. (then follows tears before bedtime!!).
A good practice when assembling Slaters wheels is to use oil on the screws - this will prevent them becoming stuck if you should ever need to remove them again.
Hope this helps
Bob

19. Les Turnbull, May 19, 2017
Regarding oiling wheel retaining screws before initial fitting I have found that slightly over oiling the axles/ wheel bearings sets up a capillary action that oils the screw threads, however the inevitable happens and the screw loosens and the effected wheel causes a derailment. Sod's law being usually in play and the offending screw is on a tender wheel and is behind a casting . I have pick-ups on my tenders, hard wired to the locomotive. Thus under these circumstances after breaking the wiring connection, removing tender body from chassis, retightening the screw and reassembly of the tender and wiring time spent is about an hour.
From this you will realise that I do not oil these screws.

20. Bob Thompson, May 19, 2017
I have probably more than a 100 locos I run regularly on my layout and I have never any issues with the screws coming loose, even after using oil to assemble the wheels.
With respect, if you have this problem then I suggest that you are not tightening them to the correct torque. The countersunk screws rely on surface friction to prevent them coming loose and unless they are tightened correctly, the underside of the countersunk head will not bed in properly with the matching countersink in the wheel bush and is likely to come loose, oil or not.
I do not oil the screw head, just the thread and I do this by using a small oiler to add a drop of oil to the axle thread before assembling the wheel. This reduces the risk of rusting of the axle or the screw, which is why they invariably lock up over a period of time. Most people will know how bad Slaters wheels are for rusting - the same applies to the axles and the screws.
Obviously “you pays your money and takes your choice” - but there is nothing worse than having to resort to drilling out the screw because it is locked in place and you have “mullered” the hex socket in the screw.
Bob

33. Nick Lowe, May 20, 2017
With regards as to lubricating the threads of the screws securing wheels to axles I use copper slip which I get from Halfords in a tube. It is available in tins but the tube has lasted me a while. It is used by mechanics to stop corrosion between threads on motor vehicles when the part may have to be removed at a later date. I have had brake calipers removed from my car after 4/5 years and the retaining bolts undo as if they were put on yesterday. I use it on Slaters wheels with no problems what so ever, the screws stay tight but undo with no trouble.
Nick

38. Simon Thornhill, May 21, 2017
Would be quite interesting to know what the correct torque for these screws is. Is there a recommended value stated anywhere? Don't remember having seen one. What I do is to put a tiny blob of copper paste on the thread.
Simon

40. Bob Thompson, May 21, 2017
Re. Post #38 -
I would go with that - the same stuff that used to be recommended to use on car brake blocks to prevent them sticking!!
You could try to check out the torque recommended for a 6BA screw, but I am not sure of what the grade of screw is that Slaters supply. They are very soft though, because they will take a HSS drill no problem at all.
Bob Thompson,

42. Nick Lowe, May 21, 2017
Re. Posts #38 & #40 -
What you state as being copper paste is better known as copper slip. As far as I am aware a paste will dry out whereas copper slip won't. Also copper slip is compressible and is used on threads to stop them from seizing due to oxidisation.
Nick

43. Paul Copsey, May 21, 2017 That's a great idea , using Coppercoat or a similar product on the screws . Now I just have to find it in the workshop , new there would be a downside . Cheers Paul

44. Les Turnbull, May 21, 2017
Re. Post #38 -
Can you get a small enough torque wrench?
Les

45. David Littlewood, May 21, 2017 I remember the old joke - the engineer's definition of how hard to tighten a bolt: tighten until it breaks, then back it off half a turn. David

46. Bob Thompson, May 21, 2017
SimonD, agree with what you have said almost entirely. I think we have diverted a long way from what was asked at the start of this thread, but the suggestion from Simon Thornhill of using Copper Paste to stop the screws from locking up is an excellent idea IMHO.
I have a tube of it in my Garage that was left over from the days when I was young enough to work on cars and I am going to dig it out.
I used it to lubricate Brake Blocks and calipers on cars which were prone to Brake squealing and a Peugeot I used to own was notorious for this.
It's sold under the Brand name of “CopperEase” and I would guess that Halfords or GSF still do it.
“CarLube” also do a small tube the details of which can be found here :
http://www.lumenalights.com/shop/Copper-Grease-Anti-seize-Lubricant-20g-Tube.html#googlebase
Bob

47. Simon Thornhill, May 23, 2017
Re. Post #38 -
Well, l recall that at work the mechanics used a torque wrench to tighten microwave couplings, where the torque was max 0.25 kgm, so l guess, yes, there IS such an animal!! No idea of the availability, or, indeed, of the rated value of the torque for the 5BA wheel screws as supplied by Slaters. There is nowt on their web site, either…
Simon

48. Phil Skoyles, May 23, 2017
Hi every body, thanks for your advice on removing wheel screws, all done now, a variety of methods, good quality socket screwdriver, drill, the best was a left handed drill, most came undone, only one had the head drilled off. There was paint in the countersink before the screws were fitted which did not help! [At this point, the post goes off topic]
Phil

50. Bob Thompson, May 23, 2017
Re. Post #47 -
To the best of my knowledge they are 6BA. This is going to be controversial and I am sure there will be certain people who rush to the defend Slaters, but what they supply (or at least what they used to supply) were of very poor quality and were as “soft as butter” so using a torque wrench is a bit of a waste of time IMHO. The later supplies from Slaters appear to be better than the chemically Blackened screws they supplied previously because they have much deeper sockets and seem to be harder. If you can find a supplier of 1/4“ x 6BA countersunk machine screws you might consider discarding the ones Slaters supply and replacing them with decent graded tensile strength screws.
There used to be a supplier called “items mail order” who would supply them and they were of far superior quality. The problem is that BA threaded screws are becoming more and more of a rarity so you might find it difficult to obtain them in the relatively small quantities the average modeller requires. If you want 10,000 or more then there will always be someone who is willing to make them.

51. Les Turnbull, May 23, 2017
Re. Post #47 -
Well, l recall that at work the mechanics used a torque wrench to tighten microwave couplings, where the torque was max 0.25 kgm, so l guess, yes, there IS such an animal!! No idea of the availability, or, indeed, of the rated value of the torque for the 5BA wheel screws as supplied by Slaters. There is nowt on their web site, either… I am still not convinced that you can get a torque wrench that will hold a hexagonal key that is 1.2mm across the flats.
Les

52. Jim Snowdon, May 23, 2017
Knowing the tightening torque tells nothing about how tight the screw/bolt is, only how much effort is required to turn it. The conversion of tightening torque into pre-load in the screw depends on the friction between the screw threads. Using a value for dry torque on a screw that has been lubricated, or indeed, contaminated by almost anything, results in an overload in the threads.
As good a rule of thumb as any is to tighten the screw with the short end of the Allen key, and when the key starts to bend, the screw is more than tight enough, assuming that it has bottomed correctly in the countersink of the

Jim

53. Bob Thompson, May 23, 2017
I think Jim's rule of thumb method for tightening the screws is just about right, always assuming that the screw is new or at least relatively new and you have an unworn key.
The only thing I would add to this is to make sure you have a decent screw and if there is a chance that it could be contaminated with varnish or paint then discard it and use a new screw. Also make sure that the key is in good condition - I have a number of keys and tend to habitually grind the end down on them to prevent the possibly of rounded corners stripping out the socket in the screw.
Bob

55. Pat Buckley, May 24, 2017
I agree with Jim as well as an old ex car mechanic I have had an awful lot of experience of tightening bolts both with and without a torque wrench and if you do it enough times you get a feel for it. The problem that I had that I mentioned in my post 10 and 12 on this thread about Slaters screws coming undone after being tightened I think was possibly quite rare ie a whole set of six screws refusing to stay tight. I am still unsure if it was the wheels that had a wrong brass centre of if the screws were wrong. I have over the years had single wheel screws refuse to stay tight but never a whole set so the question of how tight is tight is I suppose one that can never really be answered. But after nearly having a set of rods and valve gear wreaked at fairly high speed on a test track due to more than one retaining screw coming undone I am not relying on my ability to judge tightness I am using Loctite but the correct grade now !
Pat.

\ 60. John Drakeley, May 24, 2017
Hello all
6BA countersunk socket head screws in small quantities can be obtained from BA Bolt, ref traders website. They are a bit to long so need to be shortened. Not sure of the steel quality, I don't think they are high tensile steel but seem OK.
Regards John