Wheel Balance Weights

[Steve M. W]

I have posted this question here and not under Simplex as this problem may be common to other models.
I have a set of Simlpex wheel casting purchased from a well known expensive supplier that have no balance weights on, when I purchased these some years back I was told that it is standard practice and that you put the weights on your self in my ignorance I accepted this, but as I learn more in this hobby I have not found a finished Simplex that did not have the weights cast in. :oQuestion which is the best way to do it, so fare it has been suggested fill with molten lead and machine to shape but will the hot lead affect the casting? Fill with Milliput and machine this looks the easiest but will the mix stand the test of time, steam &oil. Would have taken the castings back but have part machined them. Any other suggestions would be welcome as this problem is holding up progress.

Many thanks

Steve

[baggo]

Hi Steve,

I think normal practice for wheels without the weights cast in is to cut thin metal plates to the shape of the balance weights and fit them either side of the spokes with rivets or similar. The gap is then filled with anything suitable. Araldite seems a favourite, just mix it up and pour it in. If you warm the casting up it'll flow nicely and smooth itself out. You might have to seal any gaps with tape or plasticine to stop the glue oozing out everywhere though!

This method sounds a lot easier than just filling in between the spokes and then having to shape the resulting blobs afterwards.

This also follows full size practice so it won't look out of place

The wheel castings for my Black Five are the same, the weights have to be added afterwards.

John

[waggy]

Steve,

Cutting plates and fixing either side of the wheel is the best way. Have a look at a couple of photo's of 0-6-0 tank loco's to give you an idea of the general shape and position, they weren't always fitted directly opposite the crankpin. Fix them to the wheel by drilling and rivetting, as in full size. Unless you intend to run at high speed, I wouldnt bother filling the gaps. They weren't filled in full size, only sometimes was a small amount of lead poured in when the wheel was balanced. A couple of drops of thinly mixed epoxy resin between plate and spoke helps to keep the plates in place.

Good luck,

Waggy.

[Peter W.]

Steve
I still have to do balance weights on my 5" Glen driving wheels.
Don Young said --
"I (now) believe fervently in not having balance weights cast
integral, both to increase the versatility of the casting,
which is sound economic sense these days, though the
main reason is that a better casting results"

I could add that the Glen only has balance weights on one of
the two pairs of driving wheels judging by some of the photos.

Anyway, Don recommended using ISOPON P38 filler -- from
car accessory shops etc. which machines well apparently.

I could scan in that LLAS paragraph for you if you want some more details.

All the best, Peter

[Lurkio]

Hi Peter,

Just gone through this process on a Hall 4-6-0.
I've fitted plates either side of the spokes as mentioned. It's quite a bit of work but will provide a durable result.....should look good too.
I haven't filled in the gaps yet. I may just fill in a few, as per prototype, with P38 car body repair filler.

Lurkio.

[abby]

Most loco's have different sized weights on drivers and coupled wheels , this would require suppliers to have 2 different wheels per loco - extra stock , pattern making etc etc. So quality castings tend to be less the weights which are added by the builder. with home produced sand castings being more and more difficult to get , leaving off the weight produces a "more round" investment cast wheel as the shrinkage pull is more even.

[jamienwr]

I like the sound of those ideas so if I build another loco (which could be on the cards already) but 1 quick quiestion how did you all work out where the balancing weights had to go (in proportion to the crankpin)?

sorry to throw another spanner into the works

[Lurkio]

Jamienwr,
Look at the prototype and copy that to determine the positions and dimensions.....or get the positions from photographic images. If there is no prototype then a similar loco will provide ideas.

Some of the members who have already completed engines may be able to answer this:
I understand that at our model sizes these weights are mainly cosmetic, but do these model weights actually perform any useful counter-balancing, or noticeably put the wheel out of balance? I would have thought that at the larger scales running at high speeds, big lumps on the wheels could cause some vibration.

Lurkio.

[chris vine]

Hi Steve,

I had to add plates to the drivers on my engine as the weights are bigger than on the coupled wheels.

For a filler i used an epoxy resin and mixed it up with lots of cast iron swarf from when I machined the wheels. It is obviously quite a bit heavier than plain epoxy and it worked fine.

Chris.

[ron]

If it's any help, the balance weights on Simplex wheels when they're cast in are on the opposite side from the crankpin, the ones on the driving wheels are about twice the size of the leading and trailing ones.
Ron

[waggy]

Hello all,

I once read somewhere that Oliver Bullied out-shopped one of his pacifics with unbalanced wheels, as an experimental exercise. I read this many years ago and can't really remember the result of the experiment. Food for thought?

Regards,

Waggy.

[albert]

Sirs,
There is a article in the latest Engineering in Miniature which answers most of the above questions.
Bye Albert

[daveburrage]

I think 3 cylinder engines have better inherent primary balance than 2 cylinder; this is why the Bullied pacifics got away with no balance weights. 2 cylinder engines need balance weights; though I think normal practice was to balance only 60-70% of weight (pistons con rod etc) to stop the vertical forces getting too high. Smaller weights would be required on driving wheels not connected to the con rod as only crank pin and half the weight of the coupling rods need balancing.

regards

Dave Burrage