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Bachmann BR MK1 - bogie screw thread size?


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I want to fit much longer bogie fixing screws to some of  my Bachmann MK1's for a modification project. The existing screws appear to be a machine screw thread, rather than self tapping..

 

Does anyone know the thread type and size please?

 

Andy

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Thanks,

 

That will work, but I was really hoping for a "drop in". I've made an accessory that I didn't want to have any complicated fitting for.

 

Given how many Bachmann MK1's there must be out in the field, including modified ones on EM and P4 layouts , I can't believe no-one has needed to know the thread. :O

 

Andy

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Thanks,

 

That will work, but I was really hoping for a "drop in". I've made an accessory that I didn't want to have any complicated fitting for.

 

Given how many Bachmann MK1's there must be out in the field, including modified ones on EM and P4 layouts , I can't believe no-one has needed to know the thread. :O

 

Andy

Just been and looked at my Bachman Bulleid, assume the same pivot, and the thread measures 2.01mm. IT is not BA, too coarse, so I would suggest the thread is M2.

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Thanks a bunch! I'll try that.

 

Metric threads are far less common over here in the US, so acquiring a wide range of test nuts etc., for running comparisons is not as easy.

 

Andy

Andy - we are so used to everything having metric threads here in Europe that it is easy to forget N America still uses imperial. Mind you even here getting M2 screws and nuts would be a challenge as smallest seen in most DIY shops is M3. You would be looking to specialist model shops or specialist screw supplyers. The main issue is do you need to revert to the Bachman screw. If not using a small size imperial screw looks like a posibility. Can you get BA screws. I know its British Association but the screws with Kadee couplers seem to be a BA size, 8BA I believe 

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. Mind you even here getting M2 screws and nuts would be a challenge as smallest seen in most DIY shops is M3.

Try Maplin:

http://www.maplin.co.uk/p/330-part-nut-washer-and-screw-set-n53bu

 

A box of useful metric nuts, screws and washers.

 

Keith

EDIT Or online:

http://www.rapidonline.com/FFSearchResults.aspx?filterSearchScope=1&filterCategoryPathROOT=Screws+%26+Bolts&followSearch=9954&sourceRefKey=3axEJs5yN&keywords=M2

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Thanks for the pointer - keep forgetting Maplins. I dont think it will help Andy though. Do Maplins trade in US?

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Thanks for the pointer - keep forgetting Maplins. I dont think it will help Andy though. Do Maplins trade in US?

 

We have North West Short Line who still act like traditional model engineering suppliers. I'll get some screws and nuts from them.

 

Cheers

 

Andy

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Can you get BA screws. I know its British Association but the screws with Kadee couplers seem to be a BA size, 8BA I believe 

I suspect the screw that Kadee employ is actually an American standard size (specified in inches of course) and not 8BA, although they may be a close size and pitch match

 

 

Keith

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Unfortunately B.A., metric and American threads are all different. You may require to drill out and retap. 80 thou. is about 2mm so brute force might work, but I don't recommend it.

 

Being made in China, Bachmann threads are probably metric, but since it's an American company (I think - who knows these days?) they could even be American. B.A. is unlikely as they are supposed to be obsolete. Not having any Bachmann coaches myself I don't know.

 

These might be helpful.

 

http://www.kadee.com/htmbord/screws.htm

 

http://en.wikipedia.org/wiki/ISO_metric_screw_thread

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I can't believe no-one has needed to know the thread.

Well, Bill B's replacement sprung bogies go on with the same screws as supplied, and I have yet to lose one.

If you are designing items to fit the Bachman coaches can you not just look at your coach? You will also need to know all the other dimensions of the bogie mounting.

 

No, but you could drill out the bogie pivot hole with. 4.2mm drill and tap it M5. You could then use a standard M5 bolt.

We are not talking 0 gauge here, the boss you would be drilling into is only 4 mm diameter.

 

Just been and looked at my Bachman Bulleid, assume the same pivot, and the thread measures 2.01mm.

The ones on my Mk 1s measure 1.9 on my calipers but that could just be measurement variation. They are not an M2 thread, much coarser, much more akin to a self tapping thread, but without the usual starting shape. Even so I suspect they are installed by self tapping. To use a proper machine screw you would need to drill and tap for a slightly larger size, M2.5 or the american equivalent. However the coarse thread on the existing screw will hold nmore securely.

Regards

Keith

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Update today.

 

I tried some M2 and found the same as Keith.  The Bachmann screws are smaller dia and about half the tpi. So it looks like a self tapper after all. I'll try to find a US industrial source.

 

I'm intending to add some parts below the bolster, keeping the Bachmann bogies intact. So I need a longer screw to pass through the extra material when the bogies are re-attached. 

 

Andy

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Andy - we are so used to everything having metric threads here in Europe that it is easy to forget N America still uses imperial. Mind you even here getting M2 screws and nuts would be a challenge as smallest seen in most DIY shops is M3. You would be looking to specialist model shops or specialist screw supplyers. The main issue is do you need to revert to the Bachman screw. If not using a small size imperial screw looks like a posibility. Can you get BA screws. I know its British Association but the screws with Kadee couplers seem to be a BA size, 8BA I believe 

 

I've used this company before, http://www.westfieldfasteners.co.uk/ The standard delivery was very fast indeed. No other connection to them just a happy customer.

 

Or of the USA members https://www.boltdepot.com/Default.aspx I didn't use this company, but did exchange a few e-mails with them, and they where very helpful. In fact, as they did not deliver to the UK, it was they who put me onto westfieldfasteners.co.uk

 

Hope this may be of some help to someone.

 

Ian

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