Problem Arising From My First Morgan GWR Underframe

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Super Claud
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Joined: Mon Apr 18, 2016 11:48 pm

Problem Arising From My First Morgan GWR Underframe

Postby Super Claud » Sat Apr 27, 2019 5:07 am

Hello All,
I am not sure whether this is the best place for my query or whether it would have been better in the “Wagons” section.
I have just about completed my first Morgan Design 9’ DC3 underframe, WN4420, and have encountered a problem.
The etches of the underframe body, bearing plates and fulcrum plates were formed and constructed with the utmost care as per the instructions, achieving good 90 degree bends where required. I initially elected to use No.12 spring wire as I planned to weight the van to 50g.
I could not get the recommended Exactoscale waisted bearings so substituted those supplied by Eileen’s Emporium and am using Gibson axles.

When bringing these elements together to set up a running chassis, the unsprung “fixed” axle assembled as per the instructions with the edge of the adjustable W-iron lining up perfectly with the side of the underframe body. All good and no washering needed to the fixed W-iron bearing.

To the sprung end. Having set the bearing plates into the W-irons and engaged with the spring wires, when the axle was introduced and the adjustable W-iron slid across to locate the pin point into the bearing, the edge of the W-iron was inset from the side of the underframe by a significant margin.
This appears incorrect and would mean that the axles would not be in lateral alignment along the underframe.
I have measured the axle lengths with a vernier and they are both the same at 25.95mm so I think close enough to 26.00mm.

Reviewing this problem, I have placed a 0.3mm washer from the fret onto the outside of the two sprung bearings, sandwiched between the bearing shoulder and the W-iron which appears to centralise the axle and correctly aligns the edge of the adjustable W-iron and underframe side. A trial run on the bench-top indicates the axles are running true.

The question is where has the discrepancy of 0.6(+)mm crept into the assembly of the sprung axle and whether soldering the washers onto the bearing shoulder is a suitable “fix” given the additional surface area of the washer will add a greater level of friction between the bearing plate and W-iron restricting the springing effectiveness?
Unloaded, the bearings spring back to full extension without problem but with the underframe standing on its wheels and loaded to 50g, the bearings deflect but seem to be “sticky” when lightly lifting or pressing the weight. This seems preempt a problem setting up the ride height for buffering and coupling.

Any advice would be greatly appreciated, especially from those familiar with Morgan Design underframe setting up.
Thanks in advance.

Roger

Jeremy Suter
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Joined: Tue Apr 14, 2009 6:56 pm

Re: Problem Arising From My First Morgan GWR Underframe

Postby Jeremy Suter » Sat Apr 27, 2019 9:27 am

Hi Roger
I have put together and sold plenty of the Morgan Underframes and this problem has not been mentioned to me before. My first thought was that you have made them back to front.
You have not put a picture up of the bearing in the carrier, but the bearing should not go through the carrier but be soldered to the carrier in the half etched area but this only alters it by .3mm
Have you checked the depth of the hole in the bearing there is often a difference between batches.
Regards Jeremy
Attachments
IMG_4918.JPG
IMG_4917.JPG

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Will L
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Re: Problem Arising From My First Morgan GWR Underframe

Postby Will L » Sat Apr 27, 2019 10:41 am

Jeremy may well be right and you may have assembled something the wrong way round. However there is another possible explanation. As we have discuses else where (see below), the combined length of axle and pinpoint bearings can be a bit variable, so you should not be too surprised if this sort of thing happens. It is not necessarily you.

Follow this link for an explanation of why it happens. http://www.clag.org.uk/bearing-interface.html

To see our most resent discussion on ways to deal with this read on from viewtopic.php?f=39&t=6337&p=67091#p67072

Super Claud
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Joined: Mon Apr 18, 2016 11:48 pm

Re: Problem Arising From My First Morgan GWR Underframe

Postby Super Claud » Sat Apr 27, 2019 11:38 pm

Thank you Jeremy and Will for your responses.
Firstly, I must say that I am not doubting or criticising the Morgan Design etches as I’ve not seen anything negative written about them on this Forum and shall be purchasing a few more in the future.

I have spent a good deal of time reading Brian’s instructions and working slowly through them so can say with confidence that the bearings are correctly located on the “outside” of the bearing plates within the half-etched disc.

Therefore, I will try and look at the manufactured dimensions of the waisted bearings used and in stock, the only problem being that I do not have a pin point depth measuring device to take accurate measurements. I will have to think about that.
Which of Michael Clark’s Masokit etch has the coning gauge? Sounds like a very useful item to have.
There is some irony here in that I had only recently read Will’s linked CLAG paper and the discussions in the previous “P4 Wagon Compensation” Subject but hadn’t made the possible link to my own issue.
I don’t know who manufactures the bearings sold by Eileen’s, they may be Gibson, but I was unable to get the Exactoscale bearings from C&L under Peter’s ownership so am hoping that Exactoscale will soon make them available once again, ideally through the Stores.

I’ll post updates as we progress.

Roger

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grovenor-2685
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Re: Problem Arising From My First Morgan GWR Underframe

Postby grovenor-2685 » Sun Apr 28, 2019 10:04 am

Which of Michael Clark’s Masokit etch has the coning gauge? Sounds like a very useful item to have.

I'll check when I am back home this evening.
Rgds

Philip Hall
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Re: Problem Arising From My First Morgan GWR Underframe

Postby Philip Hall » Sun Apr 28, 2019 11:19 am

I think a very crude, but effective way to check the depth of a pin point bearing would be to drill a hole in a piece of styrene sheet, perhaps about 30thou, which is an interference fit on an office pin. Push the pin through the styrene a bit more than the depth of the bearing and then push the bearing onto the pin back onto the styrene so it is flush. Remove the bearing, measure the length of the protruding pin with a vernier and you have a starting point to compare bearings with.

Philip

davebradwell
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Joined: Fri Jan 18, 2019 3:48 pm

Re: Problem Arising From My First Morgan GWR Underframe

Postby davebradwell » Sun Apr 28, 2019 4:10 pm

Why not just measure over the outside of the rigid axleguards with axle and bearings in place and work backwards from there. You don't really want to know how deep the cones are, just how wide to set the axleguards and this will get you there much more accurately. Remember waisted bearings are usually shallower than normal brgs for no apparent reason which can cause trouble. Markits bearings have the deepest cone but may require washers in most underframes.

There's some very odd features on these underframes - I don't get the single adjustable axleguard but there you are, enough folk seem to like them so I'm not after an explanation and will say no more.

DaveB

davebradwell
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Joined: Fri Jan 18, 2019 3:48 pm

Re: Problem Arising From My First Morgan GWR Underframe

Postby davebradwell » Sun Apr 28, 2019 4:18 pm

OOps, sorry, I've found a photo elsewhere and see both are removable on one side. Apologies.

DaveB

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grovenor-2685
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Re: Problem Arising From My First Morgan GWR Underframe

Postby grovenor-2685 » Sun Apr 28, 2019 9:03 pm

grovenor-2685 wrote:
Which of Michael Clark’s Masokit etch has the coning gauge? Sounds like a very useful item to have.

I'll check when I am back home this evening.
Rgds

Check not done very well, no such frets in my wagon box, so probably on a coach bogie fret but I can't find the relevant box, its to far into the loft, so can't confirm.
Attached picture shows the one I use for checking bearings, soldered to a bit of tube to make it easier to hold. The piece of fret is 22 mm long so pic is about x4.
Scan.jpg

Rgds

Bill Newstead
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Re: Problem Arising From My First Morgan GWR Underframe

Postby Bill Newstead » Mon Apr 29, 2019 11:00 am

The Masokits bearing depth jig is on the 7.02 RCH Sprung W-Irons fret. According to the instructions it is also on 7.03 BR Standard Sprung W-Irons and 7.04 BR Plate Sprung W-Irons but I don't have examples of those to check.

Regards

Bill

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Lord Colnago
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Re: Problem Arising From My First Morgan GWR Underframe

Postby Lord Colnago » Mon Apr 29, 2019 3:12 pm

If memory serves, the bearing depth jig features on all of the Masokits sprung w-iron frets.

John.
The second best priest

Super Claud
Posts: 4
Joined: Mon Apr 18, 2016 11:48 pm

Re: Problem Arising From My First Morgan GWR Underframe

Postby Super Claud » Tue Apr 30, 2019 7:40 am

Hello All,
Many thanks Keith, Bill and John for the information regarding the Masokits pin point bearing gauge. As I want to try one of Michael’s sprung W-irons as a comparison with the Bill Bedford items, this will now receive a higher priority to expedite the testing and sorting the waisted bearings I have in stock.

Thank you for your advice regarding depth measurement Philip. I was thinking along very similar lines and will adopt this to get a full set of measurements of the 2 axles/W-irons for the underframe currently under the spotlight and attempt to identify where the discrepancy has crept in to my build.

Once again, thanks to all for your input. :thumb

Roger

davebradwell
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Joined: Fri Jan 18, 2019 3:48 pm

Re: Problem Arising From My First Morgan GWR Underframe

Postby davebradwell » Tue Apr 30, 2019 4:56 pm

Don't I even get 1 out of 10 for trying?

You need to be careful with your method as you are measuring to the non-functional side of the flange. It's the back of the flange that bears against the axleguard and the critical depth dimension given by Russ Elliot in his article is correctly taken from here. If you were to get a bearing with a thicker flange it would affect your measurement but perhaps not its fit.

DaveB

Super Claud
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Joined: Mon Apr 18, 2016 11:48 pm

Re: Problem Arising From My First Morgan GWR Underframe

Postby Super Claud » Tue Apr 30, 2019 11:49 pm

Sorry Dave, I somehow thought you overwrote your initial post so included you in my final thanks. I can assure you that you weren’t forgotten.

Regarding your latest post, if I am correctly understanding you, the bearing flange is certainly going to be included with the measurements to be taken because as you say, it’s the rear face that’s in contact with the axleguard in all cases but the front face is attached to the sprung bearing plates at the sprung axle end which is where I think I have a problem.
I shall also be taking this measurement from some stock items for comparison purposes.
The discrepancy between the 2 axles is approximately 0.6mm (or 2x 0.3mm), given that a 0.3mm washer placed between the back of the flange and sprung axleguards equalises the 2 adjustable W-irons and aligns the wheels.

I’m going to try and complete the measurements and write-up over the weekend so watch this space for update.

Roger


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