Slaters S7 wheels a fitting question??

[Michael D]

Dear all,
Can anyone shed some light on a problem im having fitting some Slater s7 driving wheels please?
Im fitting them just as I always did the O gauge ones, but Im finding the securing nut doesn't go all the way in, the wheels are not being held at gauge they are sitting quite a bit proud and giving some wobble apart from not hitting the back to back gauge????
I can't tighten the screws anymore?

any thoughts please
thanks
Michael

 

[Steph Dale]

Michael,

It's the length of the square section on the end of the axle. Shorten it down and try again.

Quick test: Without the wheel, put the screw in the end of the axle until it nips up and gauge it against the wheel thickness.

Steph

 

[mickoo]

As Steph notes, the S7 hubs are thinner so the grub screw will not grip the wheel. I bore the end of the axle with a tapered bit, I think the taper angle is 60 degrees. Going in an extra mm or so will automatically reduce the height of the square section as well.

MD

 

[Dog Star]

... Can anyone shed some light on a problem im having fitting some Slater s7 driving wheels please?

Im fitting them just as I always did the O gauge ones, but Im finding the securing nut doesn't go all the way in, the wheels are not being held at gauge they are sitting quite a bit proud and giving some wobble apart from not hitting the back to back gauge?

As the Trade Liaison Officer for the Scaleseven Group I am concerned about this topic - is there a manufacturing issue with the S7 axles which the S7 group needs to take up with Slaters?

Please explain what you mean by "the wheels are not being held at gauge".

What is the back to back of the wheels when you have tightened the securing screw as far as you feel is reasonable?

When the screws are tight, how much can you move the wheels along the square end of the axle?

I understand that you have been discussing S7 with Peter Mann, are you able to show him the wheels / axles which are giving concern?

regards, Graham Beare

 

[Michael D]

Thank you for the advice,Steph and Mickoo that was really helpful, I wasn't expecting {as its my first time with the wheels} to have to make some minor alterations, but I did and they fit well now and at gauge. Its all part of the learning curve I suppose.
Quite simply put when the screw was tightened as far as it could go it left wobble on the axle and didn't hold it securely there was lateral movement on the axle a good .5+mm, the mixture of Steph and Mickoo's advice rectified it for me. I also shortened the length of the grub screw.
Interestingly checking wagon wheels with the items which arrived today from S7 stores ie my new back to back gauge I found some of the Slaters wagon wheels needed opening out a little as they were a little tight on the gauge.

On a totally positive note, I now have my first S7 loco scratch built taking shape, wheeled up ,springs working and rolling along the bench!
Very glad I went down this path...
best
Michael

 

[Eastsidepilot]

For Slater's wheels that are re-profiled for S7 the end of the axle must be shortened slightly, it can even be countersunk.

Col.

On a totally positive note, I now have my first S7 loco scratch built taking shape, wheeled up ,springs working and rolling along the bench!
Very glad I went down this path...
best
Michael

Great stuff, keep 'em coming mate.

Col.

 

[Ian_C]

Found the same thing with Slaters S7. Easiest fix is to simply file small amount off the end of the screw until it pulls the wheel up tight on the axle shoulder. The ultimate solution to all of the Slaters issues is to bore out the wheel insert and mount the wheel on a new axle!

 

[Dog Star]

After reading Colin's post I am minded to ask:-

When you write "Slater s7 driving wheels"... I take that as meaning S7 wheels produced by Slaters for and supplied by the S7 Stores. Maybe that is not what you meant... please advise.

regards, Graham

 

[Michael D]

Thats exactly what I had Graham, 5'8" drivers supplied from the S7 stores , and comparing the axles ,the ends seemed to be the same shape and size as the O gauge ones, I also bought some replacement axles SLATERS X78002S 3/16" Axle 33mm Gauge (Scale 7) to use on the bogie wheels Col reprofilled for me, and they all have the same sized square ends and all had to be modified for the wheels to fit properly.
best
Michael

 

[Eastsidepilot]

If the boss depth was the same on every S7 wheel then we could have a standardised dimension on the axle ends, but surely the depths will all be different depending on wheel type, some are flush, virtually, with the wheel face, whilst others are quite proud, in which case we have to alter the axle ends for a custom fit.
Or we assume the narrowest and have the axles made to that dim.

Col.

 

[Ian_C]

After reading Colin's post I am minded to ask:-

When you write "Slater s7 driving wheels"... I take that as meaning S7 wheels produced by Slaters for and supplied by the S7 Stores. Maybe that is not what you meant... please advise.

regards, Graham

That is what I meant.

 

[Dog Star]

This week I have had the opportunity to discuss, with David White of Slater's Plastikard, the production processes for S7 wheels and thereby the issue raised in the initial post to this topic. David was not surprised by the question of the 6BA screws bottoming in the tapped hole without clamping on the wheel. Whilst there was a problem in the quality of the screws some years back - deformation of the head such that the screw would not bear equally on the brass centre - the quality of the screws was improved with resolution of the problem through taking screw production in house and machining all surfaces of the screw. New screws are bright steel all over... old screws are "black".

The previous paragraph is an aside as the problem reported here is due to another cause.

The tapped thread in the axle ends is produced by a taper tap run into a drilled hole... where the depth of the drilled hole is deeper than the depth of the tapped portion of the hole - this is to avoid the tap from binding on swarf in front of the tap. In some instances the swarf left in the tapped hole is sufficient to stop the screw from tightening correctly. Within the last year Slater's has introduced a revised cleaning method for the axles and the procedure is intended to flush the swarf out of the hole.

If you have purchased 5'8" wheels from the S7 Stores... then the axles packed with those wheels are "older" than the revised cleaning regime. In this case, running a second tap into the hole ought to remove the residual swarf.

Or just poke around with a thin wire...

regards, Graham

 

[daifly]

Thanks, Graham. That’s very useful background information and practical advice for a solving the problem.

I have a slightly different problem with a F7 wheel-set that has been ‘thinned’ to a more correct S7 thickness. The cone of the screw is meeting the end of the square axle before it fully contacts the coned brass wheel centre. This means the the wheel is not reliably and consistently held perpendicular to the axle or to gauge. The solution appears to be to remove a little material from the end of the axle with a 60deg countersink bit. I await delivery of said bit and will report back on the effectiveness of my solution.

Dave

 

[Dog Star]

I have a different problem with a F7 wheel-set that has been ‘thinned’ to a more correct S7 thickness. The cone of the screw is meeting the end of the square axle before it fully contacts the coned brass wheel centre. This means the the wheel is not reliably and consistently held perpendicular to the axle or to gauge. The solution appears to be to remove a little material from the end of the axle with a 60deg countersink bit.

Dave, what you describe is probably par for the course when a FS wheel is reduced in thickness of the boss. We have had the same problem with diesel wheels when fitting to JLTRT Cl.37 bogies and the solution was as you have described.

 

[Lancastrian]

I think I'll be checking the 8F wheels over the weekend.

Ian

 

[daifly]

Thanks Graham

I’m a little more optimistic now that I’m on the correct path!

Dave

 

[adrian]

Whilst there was a problem in the quality of the screws some years back - deformation of the head such that the screw would not bear equally on the brass centre - the quality of the screws was improved with resolution of the problem through taking screw production in house and machining all surfaces of the screw. New screws are bright steel all over... old screws are "black".

Thanks for following this up - it is appreciated.

 

[Steph Dale]

Nice work Graham. It does explain why I perhaps have fewer problems as I tend to drop axles in an ultrasonic cleaner before doing much with them - remembering my end point is split axles.

The way the Slaters axles are machined also helps enormously with the drilling through of the axles to take insulation. And I had noticed that the more recent screws were better than the old black ones.

Steph

 

[Michael D]

Many thanks for that,
Im very glad i brought the subject up now......
Thanks everyone
Michael

 

[Lancastrian]

I've test fitted one axle to the 8F frames and there seems to be no evidence of any wobble ir the screws not tightening up enough.

Ian