Alan Gibson Loco axles

Paul Cram
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Alan Gibson Loco axles

Postby Paul Cram » Sun Feb 21, 2021 5:14 pm

Has anyone else noticed that the axles sipplied by Alan Gibson are too short? I have noticed thus with a number of wheelsets recently. Measuig the latest wheels and axles I cslculate the axle to be 1.4mm too short. The carrying wheel axle also comes up short as do the tender axles.

Philip Hall
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Re: Alan Gibson Loco axles

Postby Philip Hall » Sun Feb 21, 2021 5:27 pm

I have had this sometimes, and have thought that perhaps the axles for EM and P4 are supplied as identical? My solution has been to make up new ones from the very nice steel stock I get from Ultrascale. If I have done some turning work on the centres I often have to make new axles anyway.

Maybe have a word with Colin at AG to see if he can supply correct length axles? If all the axles, driving and carrying, are short possibly there has been an error in packing.

Philip

Daddyman
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Re: Alan Gibson Loco axles

Postby Daddyman » Sun Feb 21, 2021 5:32 pm

Philip Hall wrote: Maybe have a word with Colin at AG to see if he can supply correct length axles? If all the axles, driving and carrying, are short possibly there has been an error in packing.


I've asked him - no interest in correcting it. He said it might be because the plastic boss gets forced outwards when the axle is inserted. Whether that's the case or not, it does seem that some bosses are too proud, and so can be sanded down a bit to meet the axle end.

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BryanJohnson
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Re: Alan Gibson Loco axles

Postby BryanJohnson » Sun Feb 21, 2021 5:36 pm

Having had a delivery of pony and tender wheels a couple of days ago, you've worried me.

All the axles I've received are 22.5mm which seems right to me. (Wheel 2.3mm over centre boss * 2) +17.73mm B2B = 22.33mm

Bryan

Paul Cram
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Re: Alan Gibson Loco axles

Postby Paul Cram » Sun Feb 21, 2021 6:57 pm

I haven't fitted the driving wheels yet so it isn't caused by fitting the axle. I noticed it on the tender wheels that I had fitted and then measured the rest.

Looks like I am going to have to source some 1/8th steel rod.

Terry Bendall
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Re: Alan Gibson Loco axles

Postby Terry Bendall » Mon Feb 22, 2021 8:35 am

Paul Cram wrote:Looks like I am going to have to source some 1/8th steel rod.


Which can be obtained from Eileen's Emporium and other places.

Terry Bendall

Paul Cram
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Re: Alan Gibson Loco axles

Postby Paul Cram » Mon Feb 22, 2021 9:46 pm

Thanks Terry

Order placed.

Enigma
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Re: Alan Gibson Loco axles

Postby Enigma » Mon Feb 22, 2021 10:32 pm

I've just had to shorten some OO axles a tad, 0.4mm - which isn't much but would have shown if I had just fitted the wheels without checking.

Philip Hall
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Re: Alan Gibson Loco axles

Postby Philip Hall » Mon Feb 22, 2021 10:52 pm

Daddyman wrote:I've asked him - no interest in correcting it. He said it might be because the plastic boss gets forced outwards when the axle is inserted. Whether that's the case or not, it does seem that some bosses are too proud, and so can be sanded down a bit to meet the axle end.


I would be surprised if the wheel centre deformed to that extent. I check the dimension over the bosses with a vernier and a b-b gauge and turn the axles to precisely that length. I do this for each individual wheelset, in case there are differences, and mark them accordingly. I have never had any set on assembly turn out other than completely flush (other than a prototype where the axle does protrude a trifle).

A good source of axle steel is Ultrascale, who will supply the free cutting steel they use, and it's very nice stuff to turn.

Philip

Daddyman
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Re: Alan Gibson Loco axles

Postby Daddyman » Tue Feb 23, 2021 7:23 am

Philip Hall wrote:
Daddyman wrote: I would be surprised if the wheel centre deformed to that extent. I check the dimension over the bosses with a vernier and a b-b gauge and turn the axles to precisely that length. I do this for each individual wheelset, in case there are differences, and mark them accordingly. I have never had any set on assembly turn out other than completely flush (other than a prototype where the axle does protrude a trifle).

No, I wasn't convinced by the explanation, and your experience proves it's not the case. But as I said, there was no interest in correcting it.

Philip Hall
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Re: Alan Gibson Loco axles

Postby Philip Hall » Tue Feb 23, 2021 10:28 am

I suspect that could be a practical consideration, with such a large range of wheels. There could well be dozens of axle lengths if they were to be precisely correct, and differences between batches of mouldings would add to that.

Philip

Daddyman
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Re: Alan Gibson Loco axles

Postby Daddyman » Tue Feb 23, 2021 11:08 am

Philip Hall wrote:I suspect that could be a practical consideration, with such a large range of wheels. There could well be dozens of axle lengths if they were to be precisely correct, and differences between batches of mouldings would add to that.

Philip

True, yes.

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grovenor-2685
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Re: Alan Gibson Loco axles

Postby grovenor-2685 » Tue Feb 23, 2021 11:19 am

I haven't bought any wheelsets recently but previous experience was that they usually came a little long and needed to be shortened, given the variety of wheel bosses, supplying the axles at the longest rather than the shortest seems prerferable.
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Keith
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bobwallison
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Re: Alan Gibson Loco axles

Postby bobwallison » Wed Feb 24, 2021 9:17 am

I have experienced problems with short axles, and I model in EM!

On one such occasion I swapped them for 1/8 inch bright steel and it was a nightmare - one of the axles jammed so tight in the bearing I had to destroy the wheelset to get it out. Measuring the diameters with a micrometer showed that the Gibson axles were a few thou smaller than the stock steel. I suppose a steel rod accurately ground to 1/8 inch will not fit in a hole which is accurately reamed to the exact same diameter. Maybe some of the engineers out there can tell us if this is a real thing or if I was just unlucky.

Next time I will put the rod in the lathe and take a fraction off the diameter with flexible emery strips. Or get some Ultrascale axle material.

Regards,
Bob

Terry Bendall
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Re: Alan Gibson Loco axles

Postby Terry Bendall » Wed Feb 24, 2021 9:31 am

bobwallison wrote:Maybe some of the engineers out there can tell us if this is a real thing or if I was just unlucky.


Assuming that your micrometer is accurate and the reamer is actually 1/8 inch diameter then it may be bad luck. However usually there is a need for a few thou of clearance in a hole for the axle to turn easily. 1/8 as a decimal fraction is 0.125 inches. A 3.2 mm drill is 0.126 inches which would give a bit of clearance. A number 30 drill is 0.1285 inches which would give a bit more. That may help.

If you are going to enlarge the holes in a bearing then really some sort of drilling machine is needed to ensure that the hole remains square to the bearing face. It could be done in the lathe.

bobwallison wrote:Next time I will put the rod in the lathe and take a fraction off the diameter with flexible emery strips.


That might take a bit of time and it would be difficult to keep the rod parallel.

Terry Bendall

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Will L
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Re: Alan Gibson Loco axles

Postby Will L » Wed Feb 24, 2021 10:42 am

Terry Bendall wrote:...If you are going to enlarge the holes in a bearing then really some sort of drilling machine is needed to ensure that the hole remains square to the bearing face. It could be done in the lathe.

If I get a stiff one I spin the bearing on my 1/8 parallel sided reamer (not in a lathe as I don't have one) till it fits. Ok, it may be 0.1 of a thou or so less accentually drilled than when you started but are you really going to notice? Certainly, much easier than reducing the size of the axle.

Philip Hall
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Re: Alan Gibson Loco axles

Postby Philip Hall » Wed Feb 24, 2021 11:03 am

It may be that the axle steel stock you have is a fraction out. However, reducing it accurately is not something I would try, not least because I don’t have an accurate collet to hold it.

When I have a bearing that is a bit tight I just run a reamer in and out as Will says until I have the clearance required.

I always use steel I get from Ultrascale and I have had no problems. It’s available in many diameters and turns beautifully.

Philip

davebradwell
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Re: Alan Gibson Loco axles

Postby davebradwell » Wed Feb 24, 2021 11:35 am

You all need to read up on your "limits and fits". There's a whole load of different grades of fit covered by this standard but essentially a reamer doesn't cut undersize and steel stock sold for shafts is always ground slightly undersize so they will always fit together. Silver steel is not in this category and can be above its nominal size as well as below (+/- 1/4 thou'). Look up 1/8" shafts and you should find recision ground material to a specified tolerance and priced accordingly. Presumably Ultrascale are using some of this and it's likely Colin Seymour is, too.

Can I appeal for a nice close fit on the axle where it's relatively easy - sub thou'. You'll get plenty of slogger between the axlebox and hornblock for those that like this sort of thing.

At one time the relevant British Standard booklet was just a few quid - its equivalent is probably about £150 now.

DaveB

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Tim V
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Re: Alan Gibson Loco axles

Postby Tim V » Wed Feb 24, 2021 12:51 pm

The thing to note is that some axles sold by the trade are not 1/8" - 0.125".

Also not all supposed 1/8" reamers are actually 1/8".

Plus there is 1/8" clear.

I have a 1/8" taper and parallel (Dormer) reamer for bearings.
Tim V
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davebradwell
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Re: Alan Gibson Loco axles

Postby davebradwell » Wed Feb 24, 2021 4:15 pm

I've never heard of an 1/8" clear reamer, the size should be printed on the shaft. Reamers were bought to odd sizes for special jobs so you can have one oversize at a price. I recall a good reamed hole should be between nominal size and 3 tenths of a thou' up, certainly that's what we expected in instrument work.

This is micrometer territory, I'm afraid. If you're measuring your axle with a vernier, only a top grade branded one with appropriate manufacturers spec will get you within even a thou' of the correct size with most being up to 2 or even 3 thou' out, more if you've dropped it. That regardless of how many digits on an electronic display.

DaveB

Paul Cram
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Re: Alan Gibson Loco axles

Postby Paul Cram » Wed Feb 24, 2021 5:37 pm

Well I have now recieved some 1/8th silver steel rod from Eileens and measuring it with my Dial vernier itmeaures betwen 3.15 and 3.16mm. It seems to be asa freee running as the Gibson axles in the hornblock so I think it will be ok.. Just need to part it off to length now.

Terry Bendall
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Re: Alan Gibson Loco axles

Postby Terry Bendall » Thu Feb 25, 2021 8:58 am

Will L wrote:If I get a stiff one I spin the bearing on my 1/8 parallel sided reamer (not in a lathe as I don't have one) till it fits. Ok, it may be 0.1 of a thou or so less accentually drilled than when you started but are you really going to notice?


Sounds like a very practical idea from vast experience. :)

davebradwell wrote:At one time the relevant British Standard booklet was just a few quid - its equivalent is probably about £150 now.


Out of interest I did a bit of research on line. The current (international) standard is DIN 1420 but you have to pay for it. A couple of manufacturers give the tolerance on the diameter as being between -0/+0.003 to 0.004 mm) That should be close enough for most of what we want to do.

davebradwell wrote:That regardless of how many digits on an electronic display.


And if it is a manual vernier you wont be able to read to that degree of accuracy. :) Only a micrometer will do that and I only use a manual one.

Terry Bendall

Enigma
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Re: Alan Gibson Loco axles

Postby Enigma » Thu Feb 25, 2021 2:09 pm

I'm currently building an OO chassis (a Judith Edge kit) for someone with Gibson wheels, HL gearbox and top-hat bearings. As a matter of course I run my 1/8th reamer several times through the top-hats (including the ones provided with the HL 'box) and use the AG steel for the axles. On this build I'm finding that even after this, the wheels and axles are still a bit 'stiff' in the bearings and, as I've fitted the wheels to axles, I'm hoping it will 'run in' in due course. In some ways I'd rather have it a bit tight to start with rather than all loose and sloppy and, going by past experience, oiling and running in should help matters considerably.

bobwallison
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Re: Alan Gibson Loco axles

Postby bobwallison » Thu Feb 25, 2021 6:21 pm

Thanks to all for their input and especially DaveB for giving us the proper engineering background. BS 1916-1 seems to cover the ground, along with BS1916-2 which is the guide for the selection of fits as listed in part 1. Prices are £246 for 46 pages and £218 for 38 pages, so Dave was right about the cost as well. And at least 10 of those pages will be title sheets, list of committee members, references to other documents, blah, blah...

My mistake was using "silver steel" which I guess was at the top end of the acceptable range and maybe beyond it. Twiddling the reamer in the axleboxes didn't help, so I used even more drastic methods which I won't describe here :shock: Thankfully, the loco runs OK now.

Philip - do you buy individual axles from Ultrascale or do you/can you buy as longer rod?

Regards,
Bob

Philip Hall
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Re: Alan Gibson Loco axles

Postby Philip Hall » Thu Feb 25, 2021 7:00 pm

Bob, axle material from Ultrascale:

https://www.ultrascale.uk/eshop/products/CAT013

Material: EN1A (Leaded)

Tolerance:
(Imperial) +0/-0.0004"
(Metric) +0/-0.01mm

They supply in 6" lengths in eight different diameters.

Philip


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