Getting the wheels on square!

sam.makins
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Getting the wheels on square!

Postby sam.makins » Thu Jun 09, 2016 4:13 pm

Hi all,

I'm having a lot of difficulty getting wheels on the axles square. I've tried the GW jig but even using that I'm struggling and my particular example is right hand lead which I believe is wrong for the coal tank I'm modelling (not that you can see both sides at once).

I've got access to a unimat but can't figure out a way of mounting both wheels in it.

So, what methods do you all use to ensure squareness and eliminate wobble?

Thanks,

Sam

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Will L
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Re: Getting the wheels on square!

Postby Will L » Thu Jun 09, 2016 5:33 pm

sam.makins wrote:Hi all,

I'm having a lot of difficulty getting wheels on the axles square. I've tried the GW jig but even using that I'm struggling..


How are you struggling? One has to wonder wonder what you are doing as the GW press is normally pretty fool proof. There are some who suggest that as the hub of an AG wheel protrudes a little you need to add a support to the rim see this post though personally I have never found that necessary, which I have put down to the fact that I always include a BtoB gauge in the sandwich.
csb W&M 4.jpg


Not sure that using a lathe as a press is going to prove any easier as I suspect proper technique is the issue and using a lathe may well require more technique.

Edited to remove spelling errors and then several other strange occurrence that procured while I was trying to do the edits.
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Knuckles
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Re: Getting the wheels on square!

Postby Knuckles » Thu Jun 09, 2016 5:56 pm

Indeed!!

If you want to see how NOT to assemble wheels please watch this...

https://www.youtube.com/watch?v=gzdw968K_-4

That is how I struggled for years.

Eventually after some help from these awesome S4 lads I finally managed to get a G W Wheelpress and since then life is a lot easier. I too wonder how to put them on bent with a press. Thus...

https://www.youtube.com/watch?v=QDqQsJDPJ4k

Hope that helps a wee.
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Alan Turner
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Re: Getting the wheels on square!

Postby Alan Turner » Thu Jun 09, 2016 6:23 pm

That's NOT a tapper ream that you are using. You are using a 5 sided cutting broach - a very different animal. If you want to make a 1/8" hole then you should be using a parallel 1/8" reamer.

regards

Alan

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Tim V
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Re: Getting the wheels on square!

Postby Tim V » Thu Jun 09, 2016 6:38 pm

You've just stumbled on one of the most difficult jobs in modelling, how to get the wheels on square. But you do have a GW press, so you are most of the way there.

I have a Unimat, but I don't use it to press the wheels on. If I had time, I might make a jig to press the wheels on, but I use the GW press.

What I do use the Unimat for is ensuring the axles have square machined ends, with a very important taper on their end, just enough to take the sharp corner off, at 45° for about 0.5mm of length. Make absolutely sure there are no burrs. Then, it's a good idea to put each wheel in the lathe, mounted in the three jaw chuck is OK, to put a 5mm drill (or thereabouts) to take the corner off the wheel at the back, again no more than about 0.5mm in length. If they are older Gibsons, press the tyres off, remove the plastic sprue remains, before glueing the rim back on using epoxy. Newer Gibsons don't need this treatment.

If you have pressed the wheels on once already, and got them wrong, you will have to make new centres for them, easy on the Unimat, there is some guidance on my workbench thread where I rescued wheels.

I agree with using spacers as in viewtopic.php?p=32157#p32157 providing you have done all this preparation, the wheels will press on square.

Is it really that important you have left hand lead? An awful lot of extra work, for a benefit you can't see.
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Knuckles
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Re: Getting the wheels on square!

Postby Knuckles » Thu Jun 09, 2016 6:54 pm

Alan Turner wrote:That's NOT a tapper ream that you are using. You are using a 5 sided cutting broach - a very different animal. If you want to make a 1/8" hole then you should be using a parallel 1/8" reamer.

regards

Alan



If you mean me ok. I first got into etched kit building by watching the Right Track DVD series years ago. In there it was called a 1/8th taper reamer and I purchased a reamer with the same name as I remember. Broach is also used as Reamer interchangably by a lot of people. whether the terminology is correct I cannot say, I've always got on with no issues using the taper however.

Will buy a parallel one too and see how that goes.
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Alan Turner
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Re: Getting the wheels on square!

Postby Alan Turner » Thu Jun 09, 2016 7:13 pm

Well if someone palmed me off with a cutting Broach for a Tapper reamer I would be a tad upset.

A broach is for enlarging holes in thin sheet.

A reamer (parallel or tapper) is for producing holes of precise dimensions.

The difference:
IMG_3626.JPG


regards

Alan
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Knuckles
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Re: Getting the wheels on square!

Postby Knuckles » Thu Jun 09, 2016 8:08 pm

I see it. I had to zoom to 400% but the bottom one has sharp edges rather than flat sides.

I been using the top type.

EDIT:

Just put this comment on a couple of vids so hopefully it will not caue any issues. I appreciate correction if sound. :thumb

"IMPORTANT NOTE: I just found the linguistic difference between a Broach and a Reamer. I thought the terminology applied to both. When I mention a 1/8th Taper Reamer I meant Broach. Broaches have flat sides but reamers are usually sharp. For chassis you want broaches."
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sam.makins
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Re: Getting the wheels on square!

Postby sam.makins » Thu Jun 09, 2016 11:02 pm

Hi all,

Thanks for your help, after a few minor obstacles I think I've managed to get all 6 square and true.

There were a few issues causing me problems.

First problem was having the crankpins just a bit too long and therefore the wheels weren't sitting flat!

Second, crankpins hole not countersunk enough resulting in not sitting flush with the back to back.

And finally the use of shorting strips seems to complicate matters, A, they're the brassmasters ones with fingers that are etched a bit too thick so don't bend out of the way nicely and B, they necessitate the removal of the boss from the back so less surface area!

Sam

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Andy W
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Re: Getting the wheels on square!

Postby Andy W » Fri Jun 10, 2016 3:10 pm

Your crank pins shouldn't be near your b2b. But they should be countersunk anyway to prevent fouling.

Talking to John James re split chassis at Expo EM I realised that like me he uses wires to short his wheels (I probably nicked the idea off him in the first place!)

I wrote it up on this thread: viewtopic.php?f=19&t=2669&hilit=shorting+wire
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sam.makins
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Re: Getting the wheels on square!

Postby sam.makins » Fri Jun 10, 2016 4:32 pm

Andy,

It's one of those exactloscale btb's but I'm thinking of modifying it so the slot is bigger and clears everything better.

I did try wire after reading your thread previously but found them to be a bit of a challenge, might try them again next time though as I feel the strips are a far from perfect solution.

Sam

Alan Turner
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Re: Getting the wheels on square!

Postby Alan Turner » Fri Jun 10, 2016 4:48 pm

[quote="Knuckles". For chassis you want broaches."[/quote]

Oh dear. For bearings you need a parallel reamer of the appropriate diameter.

Regards

Alan

dal-t
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Re: Getting the wheels on square!

Postby dal-t » Fri Jun 10, 2016 5:33 pm

Agree entirely, but what I'd like someone to tell me is why I practically always have to use my 1/8" reamer on bearings for 4mm (scale!) axles, but hardly ever need my 3/16" reamer for 7mm (scale) bearings (or if I use it it hardly touches the sides - so £20 I could have spent on something else). I assumed for a while it must be to do with metric equivalents, but I note 1/8" = 3.175mm, whereas 3/16" = 4.763mm, so that doesn't seem to work. Is it that stuff about 'preferred' and 'non-preferred' sizes that always baffles me?
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Knuckles
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Re: Getting the wheels on square!

Postby Knuckles » Fri Jun 10, 2016 6:01 pm

Alan Turner wrote:Oh dear. For bearings you need a parallel reamer of the appropriate diameter.

Regards

Alan



For goodness sake. :shock: Ok will change it again when on compy next.

I've always used a tapered (flat sided whatever) as first taught and got on fine. As above every top hat bearing I've ever had needed opening out. Plus you often need to open out the etches to accomodate them, and gears often need opening.

You sure this isn't a preference thing? I believe fully you do know better on this subject which is why I'm trying to heed but you are making it confusing and myself and others have been ok with the taper reamer...that now is apparently a broach. And now it should be a parellel broach...I mean reamer!
Last edited by Knuckles on Fri Jun 10, 2016 6:12 pm, edited 1 time in total.
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Re: Getting the wheels on square!

Postby garethashenden » Fri Jun 10, 2016 6:10 pm

dal-t wrote:Agree entirely, but what I'd like someone to tell me is why I practically always have to use my 1/8" reamer on bearings for 4mm (scale!) axles, but hardly ever need my 3/16" reamer for 7mm (scale) bearings (or if I use it it hardly touches the sides - so £20 I could have spent on something else). I assumed for a while it must be to do with metric equivalents, but I note 1/8" = 3.175mm, whereas 3/16" = 4.763mm, so that doesn't seem to work. Is it that stuff about 'preferred' and 'non-preferred' sizes that always baffles me?


It probably has more to do with the manufacturers chosen sources than anything else. They probably buy rod in the size they need and then cut it to length. So, Alan Gibson will buy lengths of 1/8" rod, chances are instead of being 0.125" it's actually 0.127" or something like that. Not a whole lot bigger but enough to not fit in. It's better for the manufacturers to sell rod slightly oversized than undersized, the thought being that it can be turned down to size as needed.
You can buy ground rod that is closer to the nominal dimension, but it's significantly more expensive. Maybe the suppliers of 7mm wheels use this, maybe they have a different source who offers tighter tolerances, I can't say. But that's probably why some axles are consistently oversized.

Edit: The same thing happens with bearings and hornblocks. They are probably made undersized on the theory that it's easier to enlarge a hole so that it fits than it is to reduce an oversized whole.

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Andy W
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Re: Getting the wheels on square!

Postby Andy W » Fri Jun 10, 2016 6:29 pm

"It's one of those exactoscale btb's" Ah! I see the problem. I'd be wary of modifying it. Not easy, and a shame to butcher a precision gauge. I'd be tempted to get a standard 90° one.
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dal-t
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Re: Getting the wheels on square!

Postby dal-t » Fri Jun 10, 2016 6:30 pm

That sounds a reasonable explanation, and I have to confess that my 7mm wheels/axles and bearing all come from the same source (Slaters) whereas for 4mm I stick to AG wheels/axles but the bearings are whatever set turns up from the stock bin.
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dal-t
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Re: Getting the wheels on square!

Postby dal-t » Fri Jun 10, 2016 6:34 pm

Knuckles wrote:You sure this isn't a preference thing? I believe fully you do know better on this subject which is why I'm trying to heed but you are making it confusing and myself and others have been ok with the taper reamer...


Someone who can do a drawing will probably be along shortly to explain this graphically, but in the meantime trust me, you really, really, really do not want a tapered bearing, you want a parallel one (pair, actually, square to each other ...). :)
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Knuckles
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Re: Getting the wheels on square!

Postby Knuckles » Fri Jun 10, 2016 9:05 pm

Oky doky.

Will get one and see how much difference there seems to be. I like to prove things out.


I and others have been fine so far though. The taper is only slight.

Will buy one. Any reccomendations or shall I just grab the 1st I see? I know Eileens' sell some.
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Jol Wilkinson
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Re: Getting the wheels on square!

Postby Jol Wilkinson » Sat Jun 11, 2016 7:33 am

Available from Eileens, Chronos, Cromwell and others.

You need a hand reamer which has a square drive on the end, not a machine reamer. Those on the websites of the above listed suppliers all look similar so may be from the same manufacturer.

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Julian Roberts
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Re: Getting the wheels on square!

Postby Julian Roberts » Sat Jun 11, 2016 8:30 am

Knuckles

I share aspects of your confusion from reading this thread.

A while ago I got a 1/8" reamer, and it sorts out bearings in a jiffy if the axle won't go through. I expect it was from one of those sources Jol has listed, I seem to think I bought it at a show and said what it was for. Here is my reamer. I don't know whether it is a parallel or taper reamer but it does gradually get wider.

2016-06-11 08.29.28.jpg


At the tip it measures 0.112", and at the end of the fluting 0.122", whereas my broach over the same distance tapers from 0.109" to 0.124"

I hope this doesn't just add confusion!
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Julian Roberts
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Re: Getting the wheels on square!

Postby Julian Roberts » Sat Jun 11, 2016 9:22 am

Going back to the original question, I am glad to see Tim saying this is one of the hardest aspects of modelling.

I wonder if anyone has any thoughts re the following - (I am using the GW wheel press/quartering jig)

What I find particularly difficult is judging the B2B when using Gibson wheels, and all the more, when trying to have no sideplay, judging how much washering is needed.

On my current build (a Barclay Tank from HiLevel) my next task is to get the wheels on. The measurement over the rear (driving) hornblocks is 17mm. The wheel bosses are 0.25mm

So there is 0.17mm sideplay if I can get the B2B exactly on 17.67, with no room for any washers. If the B2B comes out slightly wider, then there will be more sideplay.

Is 0.17mm more than the minimum required for the wheels to revolve freely but with no sideplay? - I think so, but if that's right, what would be a figure to aim for? Is 0.1 more than needed still, is 0.05 enough?

The hornblocks have bosses on them which I could file down to enable me to fit in some thin washers. I wonder if it is bad practice to have no washer between a plastic boss and brass hornblock bearing. This loco is geared for max 20mph with 3'9" wheels.

I find it's hit and miss using the B2B gauge. I have trouble with the B2B turning out too wide with my Society gauge (e.g. about 17.80), but with a slightly narrower one (still P4!)from the EMGS the result is sometimes undergauge - in the 17.55mm area. Undergauge is better than overgauge for trouble free running I find. The problem is that the wheels are so stiff on the axle that fine adjustment is impossible (let alone while simultaneously retaining the quartering) - but taking the wheels off and on ruins the fit and grip, so my aim is to get them right first time... any thoughts?

I make sure the plastic wheel centre is not proud of the rims by the way, so a B2B gauge is acting on the whole wheel. And that the crankpins are countersunk inside the wheel, and not too long for the GW wheel press.

i had wondered about starting a new topic but seeing this one I hope Sam you don't mind this supplementary line.

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Knuckles
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Re: Getting the wheels on square!

Postby Knuckles » Sat Jun 11, 2016 9:52 am

Julian Roberts wrote:Knuckles

I share aspects of your confusion from reading this thread.
.................
I hope this doesn't just add confusion!


Relieved to know I'm not the only one! I think there is some mainstream confusion over correct names for the tools too, seeming that way.

Is it a Truck, a Wagon or a Van? All boxes on wheels. Add Lorry to the list if you are talking of road vehicles. I think Vans are enclosed but other than that the 1st two seem to share zero differencies. This last point was just an example, no need to explain really otherwise we'll be all taking another ballast crunch
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45609
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Re: Getting the wheels on square!

Postby 45609 » Sat Jun 11, 2016 10:59 am

Julian, yours is a parallel hand reamer. As Jol points out the way to identify them is whether it has a plain or square ended shank. Plain shank = machine reamer. Square shank = hand reamer so that you can turn it with a tapping wrench by hand.

The parallel hand reamer will have a slight taper over the first third of the length from the tip but it will be undetectable by eye. The purpose of this being to allow the user to insert the nose into a slightly undersize hole when trying to ream a hole out to size by hand. The remaining 2/3rds of the flute length will be parallel to achieve the desired fit. Usually the standard for a reamer is sized to achieve an H8 f7 clearance fit on a shaft and hole. Not much use for press fitting wheels! Having said that reamers can be reground/made to order to any desired hole/shaft fit configuration you desire. However you will typically add a significant premium to the price for this.

When press fitting a steel shaft into a plastic centre I really don't see the need to use any sort of reamer especially when it is not jigged truly square to the wheel face (i.e. doing it by hand). The likelihood of sending the bore out of true far outweighs any perceived advantage of sizing the bore for an optimum fit. So my advice is don't do it. Tim has provided the best advice in this thread so far for fitting plastic wheels to steel shafts (and linked back to a previous post by me, thanks Tim!). In a nutshell use a GW press with the outboard shims to press from the tyre and make sure the axle end is deburred so that you don't shave a sliver of plastic out of the bore as you push the wheel onto the axle.

Where a parallel hand reamer is of use is when preparing wheels for a metal to metal fit between centre and axle. But, you need machinery to do this to any degree of accuracy and get wheels really square on the axle. Take a look at stuff I've posted in this thread on RMWeb. It continues for a couple of pages and hasn't quite got to the final bore sizing yet but you should get the idea. Alternatively read Chris Pendlenton's two part article on precision wheel preparation in MRJ219 and 221.

Morgan
Last edited by 45609 on Thu Jun 16, 2016 9:45 pm, edited 2 times in total.

dal-t
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Re: Getting the wheels on square!

Postby dal-t » Sat Jun 11, 2016 11:02 am

But the discussion about reamers* was for preparing bearings, not fitting wheels to axles ...

* Although your explanation about the shape of a hand reamer was useful, because you've put it much more clearly than I would have! :thumb
Last edited by dal-t on Sat Jun 11, 2016 11:04 am, edited 1 time in total.
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