Bonding wheels to axles?

[Paul McDonoughParticipant @paulmcdonough43628]

Good afternoon all,

I am in the process of building a 3 1/2″ gauge diesel electric locomotive, my local model club suggested that “wheels should be interference fit on the axles, but if there is some give, then bond them in place.”

The axle holes in my wheels are reamed to 12mm but when I did a quick test they felt a bit loose on a 12mm ground silver steel rod.

The actual axles will be made from 14mm ground rod, machined to 12mm at each end to form a small shoulder and to fit the wheels and oilite bearings, which will run on the 12mm section, so I have the opportunity to ‘fine fit’ the shafts to the wheels but in anticipation that I might need to bond them, what should i use please?

[AStroudParticipant @astroud]

My choice would be Loctite 638 with the caveat it is quite fast setting, maybe 30 seconds before it starts to go off.

[JAParticipant @ja]

Agreed. I am about to do the same job with a 5″ Speedy. I want to use a very slight interference fit. Loctite 638 will allow this (ref: Page 3 of Data Sheet, Directions for use …… For press fit assemblies). It tells you that a high press rate is required. Trying to understand all the information on the Data Sheet, and there is an awful lot there, I think the useable setting time is far less than 30 seconds. Thinking about this the setting time could be increased by cooling the parts and Loctite slightly and not using an activator. If the worst came to happen the joint can be unglued by putting it in a very hot domestic oven.

Loctite 648 may be better (?) but I have not seen it sold in small bottles.

JA

[Paul McDonoughParticipant @paulmcdonough43628]

Many thanks, 638 looks to be a likely candidate. Apparently thicker for a bigger gap, which typically sums up my accuracy!

Just out or curiosity, why not thick super glues or araldite?

 

[Paul McDonough]

On Paul McDonough Said:

Many thanks, 638 looks to be a likely candidate. Apparently thicker for a bigger gap, which typically sums up my accuracy!

Just out or curiosity, why not thick super glues or araldite?

 

I would say ‘too close to oil’.

I use 603 though I don’t do rail wheels.

[Chris GunnParticipant @chrisgunn36534]

If i was building it I would not use Oilite bearings for the wheels, they are for light use, and low axial loads. I would use bronze bushes or roller bearings.

Chris Gunn

[Paul McDonoughParticipant @paulmcdonough43628]

Thanks again for your thoughts, I’ll check /compare each type. As for the bearings I have those already, if they wear prematurely i can change them for bronze. I did consider ball races and needle bearings but moved to simple metal bearings for ease of use.

[Paul McDonough]

On 27 March 2026 at 13:00 Paul McDonough Said:

Good afternoon all,

I am in the process of building a 3 1/2″ gauge diesel electric locomotive, my local model club suggested that “wheels should be interference fit on the axles, but if there is some give, then bond them in place.”

The axle holes in my wheels are reamed to 12mm but when I did a quick test they felt a bit loose on a 12mm ground silver steel rod.

The actual axles will be made from 14mm ground rod, machined to 12mm at each end to form a small shoulder and to fit the wheels and oilite bearings, which will run on the 12mm section, so I have the opportunity to ‘fine fit’ the shafts to the wheels but in anticipation that I might need to bond them, what should i use please?

Check the diameter of the silver steel rod you used as a gauge. Sometimes it’s a thou undersized.

[Speedy Builder5Participant @speedybuilder5]

I had to re-do my axle/wheel joints as after some running time, one of the wheels slipped on the axle (Purchase of a part built model !).

When you are quartering the wheels on the axle, there is little time between alignment and pressing on quickly, especially if you are using a press fit. When I used the Loctite 648, it grabbed after about 5 seconds let alone 30 seconds.  Others have suggested that  old out of date products exhibit these tendencies.

Good luck

Bob – 5″ SPEEDY

[Chris GunnParticipant @chrisgunn36534]

Sorry should have said “low radial loads”.

Chris Gunn

[duncan webster 1Participant @duncanwebster1]

I once broke a 1te hydraulic jack trying to remove some wheels which had been loctited on. 5″ g driving truck. Scaffold pole on the jack handle and the cylinder burst.

Having said that I’ve also had the old loctite problem, it goes off really quickly and if you are trying to adjust for quartering you are moving it while it is going off which seriously weakens it. Moral, don’t be tight, buy new for an important job like this

[JAParticipant @ja]

I am doing the quartering by using pre-machined keyways, not a jig. Trial assemblies, without Loctite, will be made. No one has yet told me that this is a silly idea.

I don’t think Phil is messing around with quatering.

JA

[duncan webster 1]

On duncan webster 1 Said:

…had the old loctite problem, it goes off really quickly…

My old Loctite 648 takes around 24 hours to fully go off. It is several hours before the parts can be handled.

Julie

[Speedy Builder5Participant @speedybuilder5]

Julie,  I wonder if the loctite 648 goes off quicker the greater the interference fit ?

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