Exacto wheels and Back to Back

Model and prototype rolling stock, locos, multiple units etc.
ginger61
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Exacto wheels and Back to Back

Postby ginger61 » Tue Jun 24, 2014 6:54 pm

Good evening all,
I am using a b2b gauge of 17.70. After assembling a pair of exacto scale wheels and using their axles I find that the wheels are wider than the gauge :? Is there any way of bringing the wheels into the same b2b? The reason for asking is that I would like to standardise as much as possible :o
Many thanks in advance,
Nick.

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grovenor-2685
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Re: Exacto wheels and Back to Back

Postby grovenor-2685 » Tue Jun 24, 2014 7:53 pm

How are you assembling them? If you assemble them to a gauge as expected then the problem you report cannot occur.
Are these carriage and wagon wheels or loco wheels?
All the C&W wheels I have assembled have gone to fit the BB gauge without closing up tight on the plastic axle centre.
Keith
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Keith
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Guy Rixon
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Re: Exacto wheels and Back to Back

Postby Guy Rixon » Wed Jun 25, 2014 8:57 am

Which BB gauge are you using? The Exactoscale one for P4 is listed as 17.75 in the C&L catalogue. 17.70 rather than 17.75 is maybe OK, but I think the big, heavy gauge may be a necessary part of the process. If you use an L-shaped BB-gauge, or if you don't make the assembly jig specified in the instructions, then it would be more likely that the wheels get displaced while the retainer is curing.

Eastern
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Re: Exacto wheels and Back to Back

Postby Eastern » Wed Jun 25, 2014 9:15 am

When I first used them, I did have the second wheel move for some reason (lack of care on my part). Now I make sure that I arrange for some light (very light) pressure on the centre of the second wheel to make sure it stays fully against the B2B gauge and square until the retainer has hardened. No problem since I adopted this approach.

Incidentally I use a GW adjustable B2B gauge which provides full support around the wheel rim.

ginger61
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Re: Exacto wheels and Back to Back

Postby ginger61 » Wed Jun 25, 2014 2:43 pm

Hi all,
Many thanks for the replies. The b2b gauge was bought a couple of years ago from Bracknell along with track gauges!! But are definitely p4 gauge. The wheels in question are 3 hole disc for wagons. The axles have 1mm points and what appears to be plastic as the middle part. Guy, instructions? Ummmm not found any to date :o I did come across them but I'm blowed if I can remember where they are or where in the pc memory they went to?
It's just that all the talk of "which b2b people use, and why" that I'm not sure as which one, but as long as it is between 1 figure and another figure that's ok :shock:
I hope that has spread some light on what I'm trying to achieve and will in some way make it easier for the "elder statesmen" to see whats what and where's where!!!
Many thanks in advance,
Nick.

Philip Hall
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Re: Exacto wheels and Back to Back

Postby Philip Hall » Wed Jun 25, 2014 3:23 pm

Instruction for the assembly of Exactoscale wheels used to be on their website. Hopefully this will have migrated across to C&L and will be there. Failing that someone on here will have them I'm sure.

I would also endorse the use of the GW adjustable B-B gauge, a precision piece of kit. The adjustment was, I think, intended for those of us who flit between the various 4mm scale gauges, but is equally at home for setting the B-B to your chosen value. It does, however, require the use of a micrometer or vernier to set it up.

Philip

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grovenor-2685
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Re: Exacto wheels and Back to Back

Postby grovenor-2685 » Wed Jun 25, 2014 4:41 pm

I hope that has spread some light on what I'm trying to achieve and will in some way make it easier for the "elder statesmen" to see whats what and where's where!!!
Well, now we know which wheels but not what the problem is, the plastic centre on the axle is intended to represent the taper of prototype axles, first thing is to check that the plastic sleeve is central on the axle and adjust if not. In all of the ones I have assembled pushing the wheels against the plastic sleeve leaves the BB a bit under, hence the need to use the gauge while the loctite sets up, and to take care the the pinpoints extend the same length from each wheel.
if you are getting an excessive BB when the wheels are pushed fully up to the plastic centres something is wrong, it could be that the stub axles are not fitted to the wheels correctly, they should be pretty well flush on the outer face, if neccessary the stub axles can be adjusted in the wheels or you coould shorten the plastic a bit.
Keith
PS. just checked a couple of pairs out of the packet, as they come the BB is between 17.5 and 17.6 with the stub axles pushed against the plastic centre, they have to be held off to get 17.7
Regards
Keith
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Russ Elliott
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Re: Exacto wheels and Back to Back

Postby Russ Elliott » Wed Jun 25, 2014 5:09 pm

Exacto C&W wheels had a 2mm o.d. 1mm i.d. brass bush in the wheel, which fitted on the 1mm steel (pinpoint or plain) diameter axle, which have a shaped plastic overmoulding. The brass bush is not a particularly tight fit in the plastic wheel centre, and benefited from adhesive prior to wheelset assembly. As Keith says, wheelset assembly was with loctite, the 1mm interface dimension being a running fit, so the use of an Exacto parallel-sided BB block gauge was essential.

exacto-wagon-1mm-pin.png
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grovenor-2685
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Re: Exacto wheels and Back to Back

Postby grovenor-2685 » Wed Jun 25, 2014 7:06 pm

The normal 'L' shaped gauge has always worked fine for me, never needed an Exacto or a GW version.
Keith
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Keith
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Guy Rixon
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Re: Exacto wheels and Back to Back

Postby Guy Rixon » Wed Jun 25, 2014 9:27 pm

ginger61 wrote:Guy, instructions? Ummmm not found any to date :o I did come across them but I'm blowed if I can remember where they are or where in the pc memory they went to?


They moved. Now available at http://www.finescale.org.uk/index.php?route=information/information&information_id=31 which is in C&L's main domain and therefore probably stable.

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Guy Rixon
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Re: Exacto wheels and Back to Back

Postby Guy Rixon » Wed Jun 25, 2014 9:40 pm

grovenor-2685 wrote:The normal 'L' shaped gauge has always worked fine for me, never needed an Exacto or a GW version.
Keith


Jolly good, I'm glad it works for you. Me being inept, I found that the (few) sets I assembled with a L-shaped gauge tended to be loose on the gauge after curing. No such problem with the Exactoscale gauge.

andrew jukes

Re: Exacto wheels and Back to Back

Postby andrew jukes » Thu Jun 26, 2014 10:05 am

Having (as Exactoscale) sold these wheels at exhibitions without ever having used them myself, the methods I've adopted when assembling a whole train's worth of wheelsets may be of some interest. A few initial points:

First, I believed the design of the mould forced the moulded centre section of the axle to be centred on the steel axle. Checks on several axles seem to bear this out - so no need to attempt any adjustment of its position as suggested by Keith.

Secondly, I initially worried about equalising the gaps between the wheels and the moulded axle centre. A few moments thought indicated this to be silly. Even with a 17.82mm B-B, zero gap at one side and a 0.3mm gap at the other, the offset between the track centre line which the wheels will centre on and the vehicle centre line will be only 0.15mm. Not a problem, I feel. What I do do is make sure the wide gaps are always on the same side of the vehicle or bogie so the wheels are running in line. Cosmetically, some might wish to fill the 'wide' gap, but it is pretty hard to see under a coach.

Thirdly, Russ writes as though these wheels are history. Not so - you can buy them currently from C&L. Also as I mentioned in the Wheel Profile thread, I am encouraging Pete Llewellyn to have another batch of Exactoscale-style B-B gauges made (17.75mm, 17.82mm or 17.87mm) and anybody interested should let their interest be known to Pete or me.

As to assembling the wheelsets, I have a block of MDF with half a dozen 1.0mmØ holes drilled vertically in which I insert axles (having cleaned up any sprue residue, particularly at the ends of the moulding, and inspected the pinpoints). I then inspect half a dozen wheels to make sure the rims are pressed on properly (occasionally they're not) and to make sure there is no moulding sprue residue that might might get in the way of setting the B-B correctly. I then, one by one, put a drop of Loctite 603 in a wheel bore and on the upper end of an axle, put the wheel on the axle, wipe of excess Loctite, gently spin the wheel, lift it a little, spin it again and let it settle on the end of the axle moulding (and check that's where it is). I then avoid touching that one again and work my way along the others. I then leave these 'half wheelsets' for hours if not days.

When well-cured, I do a demanding test. I put the free end of the half wheel set in a 1.0mm collet chuck and check the wheel runs true. Four out of five are usually as good as perfect, a fifth might be not quite as good and is put to one side for secondary (i.e. not a streamliner!) use.

From then on, I pretty much follow the instructions. I have a suitable hole to take the axle and wheel centre boss drilled in a piece of MDF, place the half wheel set with its wheel rim on the MDF and boss in the hole and place the Exactoscale B-B gauge on the wheel back. I then put a drop of Loctite in a wheel centre and on the free axle shaft, spin the wheel down the shaft till it is well-seated on the face of the B-B gauge, wipe away surplus Loctite, check that everything is nicely aligned (lower wheel boss still positioned in hole, axle not touching B-B gauge) and place a weight on the top wheel to make sure it is truly in contact with the B-B gauge surface (the weight need not be heavy but must load the wheel symmetrically). Using a weight at all is probably unnecessary but gives me some extra reassurance.

After a few hours, I remove the weight, pick up the B-B and slide the wheel set off the gauge. I get a small variation in just how tight the wheelset is on the gauge, but I have been happy with all of them so far.

Regards

Andrew

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Russ Elliott
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Re: Exacto wheels and Back to Back

Postby Russ Elliott » Thu Jun 26, 2014 10:50 pm

Apologies, Andrew; my message should have been written in the present rather than the past tense.

ginger61
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Re: Exacto wheels and Back to Back

Postby ginger61 » Sun Jun 29, 2014 8:46 am

Gentlemen,
Many thanks for the replies. I have now got the gist of the wheels but now need a 17.75 b2b gauge so the wheels sit right. Keith, I wasn't being flippant when I said "elder statesmen" as there a lot of p4 modellers who have being doing this a lot longer than me :o Andrew, thanks for the explanation on how to assemble the wheels :thumb Just what the Doctor ordered.
Once again many thanks for the replies.
Cheers, Nick


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