A Chequered Chieftain at #10

[Richard Goodwin]

So this weekend has been all about finishing off the hub caps. In order to do this, I need to make some bolts and drill the two blank holes which I think are for a spanner of some description but not sure?

To make the bolts, I'm using M1.4 x 6mm bolts and associated nuts. Now these are really small and if your eyes are anything like mine, you'll need a magnifier of some description. I used one for virtually all the following process with the exception of drilling. In addition, it helps if you have long nails to grip these little buggers as well!

So firstly, screw a hub cap fully onto a hub; this will be used as a depth gauge. Install a nut onto a bolt and insert into one of the holes in the hub cap. The idea here is to get the nut to sit flat against the hub but at the same time, get the maximum amount of thread in the hole.

This gives a rough idea of where the nut needs to sit and was then secured in place with a dab of Loctite Blue then rechecked to ensure the nut sat flat against the hub cap flange before the Loctite went off. This was repeated another 83 times plus a few spares.........you may lose a few when you come to finishing them

Whilst the bolts are drying, a hub cap was secured in a vice upside down and the bolt holes slightly countersunk using a 2.5mm drill...

The reason for doing this is to create a greater surface area for a plug of Loctite to grip for greater security of fixing.

WIth the Loctite blue hopefully cured, the fun now started.........I gripped the bolt assembly by the with a pair of old electricians plies and with a firm grip on the pliers, proceeded to cut the head off the bolt assembly using a Dremel with a cut off disc installed. This needs to be done slowly since there is a lot of heat generated here so little and often is the best way! (apologies for the pic quality on this one)

This same disc was then used to slowly remove the remaining thread down to the nut.

With the bolts now created, I masked up the holes on the underneath of the hub cap then installed that hub cap fully onto a hub.

Taking one hole at a time, the hole was filled with Loctite 401 and using a pair of tweezers, a bolt assembly was placed into position. A piece of kitchen roll was used to soak up any excess Loctite and the bolt finally positioned before moving on to the next one.

After a couple of hours, the masking tape was removed. I found that some holes needed topping up as you can see below....

With the upside down hub cap resting on the hub, the holes were topped up and overfilled with Loctite and allowed to harden for a few hours whereupon any excess was filed off.....

After filing......

A hub cap was then fully installed into a hub and using a centre punch, the position of the two diagonally opposite holes was marked; no measurement here, just done by eye. The hub cap was then unscrewed from the hub by around a turn and a half and the hub secured in a vice whereupon the two holes were drilled using a 1.5mm drill.

After a quick degrease, the hubs were sprayed with etch primer which is very good at showing up imperfections as you can see....

A quick regrind and paint......all's well! I think it's pretty close to the original.

[Vince Cutajar]

Really love your step by step description of how you do things. Keep it up. Out of curiosity, how come you did not use 1.4mm hex head bolts?

Vince

[Richard Goodwin]

Thanks Vince. There's a lot of good stuff that happens on here but people don't necessarily show how they got there! I'm not saying that what I do is correct but at least newbie's like me, can easily understand with this type of instruction.

I was going to buy some actual M1.4 bolts and nuts but John Clarke showed me these below which cost around a fiver for the two packs needed plus, you get lots of other sizes as well as rivets too! Actual M1.4 bolts cost a fortune in comparison and I've already spent enough

[Stephen White]

Richard, congrats, they look good and you're doing a great service to the community in sharing your methods. As you rightly say, some are pleased to show off their work but chosoe not to show their methods. Nothing like a few state secrets....

[Vince Cutajar]

Actual M1.4 bolts cost a fortune in comparison and I've already spent enough

That's a good reason.

Vince

[Richard Goodwin]

My Mother had a saying; look after the pennies and the pounds will look after themselves Besides, I have a melting pot to save up for to make my Stillbrew

[John Clarke]

For a split second there Richard I thought you'd mounted the on hubs on upside down.
Loads of extra work, but worth it. Good job.
They look really good, almost as good as mine

[Richard Goodwin]

This weekend, it was the turn of the road wheels to be assembled; bearings and all......

I was advised that when installing the bearings that I should not preload them ie tighten the fixing screw nor should I add any additional end float ie the M4 washer under the end cap (CP0142) so thats the guidance I'm going to follow. Further more, since each hub will be fitted to a specific shaft, that pairing will stay together as will the road wheels themselves as they become part of the hub assembly. Each will be uniquely identified to enable refitting to the appropriate shaft; how I do that will be in tomorrows brief when I add the road wheels.

So the first port of call is to install the bearings of which there are two per wheel hub, one on each side. The first thing I did was to gather all the tools, parts and glue together in close proximity; this is because I will be using Loctite 648 to fix the bearings in position and therefore, I have about 4 minutes before it goes off so no time to hang around!

The brush by the way is for spreading the Loctite evenly inside the housing.
Before I started, I checked that each bearing could fit in either housing and that both bearings could fit over the shaft easily; both those checks are important since you don't have the time to make adjustments once the Loctite is applied and the bearing installed. When trial fitting the bearings, its here that you'll find out if you have removed the burrs sufficiently since if you haven't, they will be hard to push into place. similarly, if you have, the bearings will just drop in and fall out with little assistance.

So with the checks done,I put a few drops of Loctite in one of the bearing housings and distributed it evenly around the housing. Don't put to much Loctite on otherwise all that is going to happen is that it will be squeezed out when you fit the bearing whereupon you run the risk of locking the bearing up! Also, avoid getting any on either the screw thread or the bottom of the hub for similar reasons...

The bearing was placed into position and the process repeated for the other bearing. With both bearings in position, I installed the hub onto the shaft keeping a finger over the top of the hub to ensure the top bearing wasn't pushed out. The end cap and the M4x10 securing screw were installed and the screw was tightened down until I could just start to feel it tighten up then it was backed off between a quarter and half a turn.

The hub was then spun slowly at first to centralise the bearings on the shaft and within the housing. Occasionally, the screw tightened up so it was backed off again.

The hub was spun every 30 seconds or so for 10 minutes to ensure that it wasn't starting to lock up through excess Loctite.

After 20 minutes, the hub was removed from the shaft and any excess Loctite cleaned off with a little rag and degreaser before being re-fitted. The process was then repeated for the remaining 11 hubs and shafts.

Tomorrow.....fitting the road wheels to the hubs

[Richard Goodwin]

Yesterday was all about centralising the bearings on the wheel shaft in order to obtain smooth running, minimise end on wheel wobble and to promote a lengthy bearing life (he says hopefully) Today is about fitting the road wheels to the hub to ensure minimal visible wheel wobble when looking from the side; now that would be relatively easy if this was a single wheel but its not, it's two wheels per hub and that's where the complication lies! There is a lot of play available between the hub and the wheels so it is quite easy, to secure the wheels off centre to the hub thereby giving the visual impression of wheel wobble. So I came up with the following process to hopefully overcome this.

Previously, I had prepped the road wheels by re drilling all the bolt holes because of flash, rubbed down, washed and degreased, masked off the edge and etch primed both sides of the wheels. In addition, I had fully painted and varnished the inside facing faces of the wheels (avoiding the areas where the two wheels would touch) since this would be difficult to do once assembled.

When you compare the original wheel fixings that can be seen externally, the securing nut on the outside resembles that of a Nyloc nut. To this end, I will be replacing the originally supplied nuts and bolts (left side of below pic) with M3 x 14 Hex head bolts and M3 Nyloc nuts (right side of below pic).

So that's the starting point, now on with the process.........

I first aligned two wheels back to back ensuring that all bolts holes were fully aligned with each other and secured using 4 of the supplied bolts and nuts. I used a straight edge to ensure the wheel edges are aligned as well as rolling the wheel assembly over a flat surface to look for any wobble. With the nuts tightened up, the alignment was rechecked and if ok, 45mm 'gaffer' tape was wrapped around the wheel......

The idea of the tape is to hold the two wheels together in alignment whilst the securing bolts are undone and the hub installed using the same 4 bolts but this time with washers underneath to assist with moving the wheels in relation to the hub. In addition, it will keep the wheels relative position when moving them around the hub. With the hub in position, the complete assembly was installed onto its appropriate shaft and secured with an end cap and securing screw but this time, I added an M4 washer under the cap end and fully tighten the screw. I also ensured that the wheels could be moved in relation to the hub; if not, the nuts were slackened until I could. The wheels were the spun!

With the wheels spinning, you can visually see if the wheel is running in a circular pattern or if it is off centre, an elliptical one! If elliptical, note where the high point is and adjust the wheels accordingly. When I thought the wheels were running true, the nuts were re tightened and the alignment rechecked. If all was ok I then checked to see if I could install my replacement bolts in all the available holes; if I couldn't then the alignment was rechecked!

The replacement bolts and Nylocs were then fitted to all the free holes with an M3 washer added to the head end to reduce the amount of thread protruding from the Nyloc. Although the Nylocs I used appeared to have very good 'grabbing' characteristics, I still used Loctite Purple to secure. The supplied bolts were then removed and replacement bolts and nuts installed.

The assembly was rechecked to ensure the wheels were centred around the hub and if ok, was degreased and the whole assembly etch primed.

With the assembly finished, I knew that from the side view, the wobble was all but eliminated but i hadn't as yet checked the end view! With a bit of a heath robinson affair, i determined that the maximum end on wobble was just under 1mm as you can see below.......

The wheel assemblies were then painted and a unique numbering system applied to each wheel assembly using 3mm letters/numbers secured with super glue to identify the specific position the wheel assembly came from. 'L' and 'R' being Left or Right and the number being which Bogie. Finally, the wheels were varnished...

Repeat a further 11 times, add the hub caps, the occasional tyre which btw, hasn't been fixed into position yet (that's later) and all done!

[Manny Leung]

Wow what a meticulous and precise build! I assembled all my wheels on my lap whilst watching the telly!

[Richard Goodwin]

I can neither confirm or deny Manny

[John Clarke]

648 loctite, you're certainly going for it with that stuff.
A Well built loverly job. May all your road wheels be wobble free.

[Richard Goodwin]

Have been playing around today with 'MY' recoil for the Chieftain which you can see working here:

https://youtu.be/blM1xo_TgWY

The above test as you can see was done under no load conditions; I have no doubt when I try and pull that barrel back, the current will increase significantly so I intend to power just the servo from its own voltage source via a 5V regulator.

I can vary the speed and the amount of movement for each element of the recoil as well as the LED flash rate and the type of flash. I do need to do some measurements of recoil speeds and distances but if anybody has these already, that would be really useful?

[Adrian Harris]

Some of these larger servos can work from supplies of 6V to 8.5V, and give much improved speeds and torque figures at these higher voltages.

Adrian.

[Richard Goodwin]

Many thanks for that Adrian. I did search the Part No of the supplied servo but couldn't find anything; I was hoping to get some specs. The highest voltage it appears to take is 7.2V which I should be able to find a regulator to give that; the problem is the current draw needed. Would you have any idea of what sort of current we would be talking about here.....3 or 5A perhaps?