Page 1 of 1

Assembling Exactoscale wagon wheels.

Posted: Wed Nov 25, 2020 7:49 pm
by jimphillips
I have some Exactoscale wheels to assemble. In the instructions INS 551, it shows 0.1mm gaps at positions 1 and 2, that is adjacent to each wheel, for the correct back to back dimension. Following the step by step instructions I can't see how to achieve these gaps, unless I have missed something. The first step is to affix one wheel to an axle but no mention of the 0.1mm gap? I can't see it being anything to do with the 50mm square block(item 2, as detailed in INS 552). I appreciate these gaps must be there to achieve the correct back to back, but how to achieve this and keep them equal at both sides I am struggling with.
How does anyone assemble these very nice looking wheels? What methods have you used to assemble them?

Re: Assembling Exactoscale wagon wheels.

Posted: Wed Nov 25, 2020 7:59 pm
by Will L
I punch 1mm holes in small squares of paper*, assemble the axle with a square of paper right behind each wheel. Tare them out when the Loctite has gone off. Simples.

If your really picky you might worry about the thickness of the paper.

* Use the pinpoint on the axle to press through into a hole, then trim the raged edge with a scalpel.

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 11:01 am
by davebradwell
The gaps don't have to be equal, just as long as you don't push the wheels up to the axle sleeve and expect the correct b-b. It's difficult to get these wheels to run true without the Exacto b-b gauge as you need to hold the axle perpendicular to the wheel due to the clearance in the hole. Just be sure you have the same amount of axle sticking out each end before the Loctite goes off, if it isn't too old. Careful with any paper, the first bit I picked up was just over 0.1 and you don't want to "influence" the position set by the jig.

DaveB

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 1:10 pm
by philchudley
Are these used for axle spacing to get the correct B to B?

4CW701A Axle spacing washers 1mm i/d (etched) (Exactoscale)

Phil

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 1:27 pm
by johndarch
I make oversize washers out of 5 thou styrene which are trimmed to shape after assembly.

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 1:29 pm
by Will L
philchudley wrote:Are these used for axle spacing to get the correct B to B?

4CW701A Axle spacing washers 1mm i/d (etched) (Exactoscale)

Phil

See the instructions which are on the society download area. Particularly stage 6.

I think those washers are actually intended to locate the parallel sided axles between the bearings

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 2:12 pm
by davebradwell
5 thou' is more than 0.1mm which is pretty close to 4 thou'. Why do you want to put washers in the gaps and which will prevent you getting equal pin-point protrusion each end?

DaveB

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 3:23 pm
by Guy Rixon
For stage 6 of the instructions, fitting the first wheel, I plant the free end of the axle in a 1mm hole drilled in a square of hardboard. The blutack solution didn't appeal to me.

A cautious man would arrange some clamping force when fixing the second wheel so that it can't rise up the axle. I've not bothered, and things seem OK. If the assembly were clamped, a slight over-thickness of the paper washer would not matter as it would be crushed down.

It's tricky to make up these wheelsets without a back-back- gauge that acts as a jig, like the Exactoscale one. The L-shaped gauges do not give the same support and surety of success. Note that the Exactoscale gauge sets back-to-back to 17.75 mm for P4 (17.87 mm if you buy the S4 one) and the 0.1 mm figure for the gaps is stated for 17.67 mm back-to-back.

If you leave out the paper trick then both wheels will be offset ~0.25 mm towards one axle-end. This won't matter too much with the parallel axles as you have to use the little washers to take out the play (otherwise the wheels fall out of the bearings) and this will centre things up. For pinpoint axles, one would need to get the gas on the same side for both (all) axles to avoid crabbing.

The washers in the Exactoscale range are too thick for taking out the gaps behind the wheels.

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 8:01 pm
by johndarch
With two washers the length of the pinpoints will be the same each end. 2 x 0.03mm is just 0.06mm. This is less than the difference between some back to back gauges.

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 8:10 pm
by jimphillips
Thanks for all your help and advice fellas.
Will L, I had actually thought about using the paper method but thought it might have been frowned upon, but obviously you have used this method satisfactorily. Think I am going to try it.Simples.

Re: Assembling Exactoscale wagon wheels.

Posted: Thu Nov 26, 2020 8:52 pm
by davebradwell
The purpose of the gaps is to allow for possible variations in the length of the plastic sleeve so care is necessary if working from this. We do, however, have the advantage that we can check the sleeve before going ahead - obviously not possible when designing the tooling. Wobbly wheels are still the main hazard when departing from the official jig.

DaveB

Re: Assembling Exactoscale wagon wheels.

Posted: Fri Nov 27, 2020 4:59 pm
by jimphillips
Ok Dave point taken, is the Exactoscale b-b gauge still available?

Re: Assembling Exactoscale wagon wheels.

Posted: Sat Nov 28, 2020 9:44 am
by davebradwell
Gauges were no longer available when I asked last Scalefourum and I've never managed to get the wheels running truly as I don't have one. The official instructions claim that the first wheel will go on square of its own account, given a bit of fiddling to get the position right. Guy uses his block here but he can't be getting much engagement on the axle so it will take care and there's a danger of sticking the whole lot to the block. Probably your best chance, though. I've always tried to put both wheels on together but my home made jig wasn't made with such accuracy in mind. Must try harder.

A bigger challenge with inside bearing pony wheelsets, if course.

DaveB

Re: Assembling Exactoscale wagon wheels.

Posted: Sat Nov 28, 2020 11:23 am
by Guy Rixon
In fact, I use my square of hardboard just to secure the axle pointing vertically, not to align the the first wheel to the axle. The axle end goes into the block for the full ~3 mm depth of the board. I rely on the goodness of fit between wheel and axle and the retainer to set the first wheel true.

Re: Assembling Exactoscale wagon wheels.

Posted: Sat Nov 28, 2020 12:37 pm
by grovenor-2685
Guy Rixon wrote:It's tricky to make up these wheelsets without a back-back- gauge that acts as a jig, like the Exactoscale one. The L-shaped gauges do not give the same support and surety of success.

I find the L shaped gauge very capable for this purpose, the contact the tyre in 4 places and consequently hold the pair of wheels correctly parallel just like the Exactoscale gauge. Both depend on the first wheel being set accurately first, and that relies on the loctite being evenly distributed in the joint by turning the wheel as per instructions above.

Re: Assembling Exactoscale wagon wheels.

Posted: Sat Nov 28, 2020 12:50 pm
by davebradwell
Yes, it's easy to get them to run almost true but that last little nudge has always eluded me. My gauge has parallel faces but the axle slot is just a tiny bit out (it wasn't intended for this job) and that stuffs it up. They are a very nice wheel, however and even with a small wobble are very reluctant to derail.

DaveB