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Post by westlin on Jun 29, 2020 15:46:33 GMT
I need to replace the guide bars on my 3 1/2 britannia, the challenge is finding some bms of the correct size. They are made from 5/32 × 1/2. Can any suggest a supplier or spare some that I can buy off you. The metric equivalent is 4mm and I can find any bms in that size.
Thanks
Stephen
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Post by Roger on Jun 29, 2020 16:17:03 GMT
Hi Stephen, Why not make them from this Flat Ground Stock? It's already to the size you want. What is the other material it's bearing against? |
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mbrown
Elder Statesman
Posts: 1,719
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Post by mbrown on Jun 29, 2020 16:39:08 GMT
I made the slidebars for "Lyn" from GFS, as Roger suggests, 5/32" x 1/2". I used bronze slippers on the crosshead. If I remember correctly, it was cut for me from a larger piece. That supplier is no longer trading, but I believe M-Machine Metals in Darlington stocks GS and will cut it to requirements. Usual disclaimer, but their service is excellent and their prices reasonable.
Hope that helps.
Malcolm
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Post by westlin on Jun 29, 2020 16:50:29 GMT
Roger, it looks like the cross heads are steel. How easy is ground stock to tap as the are held on with 8bs bolts so not massive taps if the material is going to be hard.
Thanks
Stephen
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Post by ettingtonliam on Jun 29, 2020 16:58:16 GMT
Its OK to tap as in its non-heat treated form its tough rather than hard. Invest in a new set of HSS taps to give yourself the best chance.
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Post by westlin on Jun 29, 2020 17:56:28 GMT
Thanks for this
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Post by Roger on Jun 29, 2020 19:02:52 GMT
Roger, it looks like the cross heads are steel. How easy is ground stock to tap as the are held on with 8bs bolts so not massive taps if the material is going to be hard. Thanks Stephen Hi Stephen, It's about 50% more difficult to machine Ground Stock compared to Mild Steel, so it's not really a problem. Just take it gently and swap between taps if the resistance gets to the point where you think it will break the tap. Any amount of turn with a tap is a victory, so just swap from say the Second to the Plug for the next small turn and then change back. That way you can cut almost any size thread in any material, even if the tap is a bit blunt. |
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dscott
Elder Statesman
Posts: 2,437
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Post by dscott on Jun 29, 2020 23:18:10 GMT
Such lovely work again Roger.
This is so grown up AIRFIX KIT that I am sure we all dreamed about when we were much Younger.
Now for the ULTIMATE PHOTOGRAPH and I did one of my Gemma when I was 27...
All the parts laid out just before they all go together.
Yes it takes hours but it was lovely to do.
Then I got Married!!!
Early days Superb and Gemma steamed nicely as well.
I did so much back then with a little vice attached to a small box.
David and Lily.
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