Metric Brass flats

[1Participant @1]

Evening all

I'm building Bogstandard's Paddleduck engine and I have got as far as the eccentric straps. The plan calls for 4mm thick brass 21mm wide and I reckon a strip 300mm long would suit.

I have been unable to locate any such size, can anyone give me a steer to a supplier please?

Jim

[1Participant @1]

[NJHParticipant @njh]

Jim

You could get some imperial  – 1" x 1/8" -brass strip  HERE The 1" you could reduce to 21mm and I doubt that the difference in thickness between 4mm and 1/8in.would be a problem.

(You could, of course, ask Bogs where he sources his material ! )

Cheers

Norman

 

Edited By NJH on 05/01/2013 00:50:57

[JasonBModerator @jasonb]

It was probably cut from 4mm sheet which is readily available and some of our suppliers may cut you a thin slice off the side of a sheet as buying a 300×300 sheet is pricy.

Machine it down from 3/16×1 or as norman says 1/8×1 would likely do the job.

Edited By JasonB on 05/01/2013 07:43:50

[JoParticipant @jo]

You could always cut a 4mm thick slice off a larger diameter piece of brass bar.

jo

[Russell EberhardtParticipant @russelleberhardt48058]

Tartaix in Paris stock 20 x 4 and 25 x 4. They will cut to any length and supply mail order. Don't know if they will post to UK though but if you're stuck you could ask. Try emailing them on [email protected]. Their website is in English and French so I'm sure they will speak English.

Russell.

[1Participant @1]

I didn't really want to thin down an imperial size because turning brass into swarf seems to be an expensive hobby best avoided if possible but that seems the way I will go.

Thanks for all suggestions.

Jim

[JasonBModerator @jasonb]

You could always make them from Cast Iron, a couple of slices off the end of a bar will be fine and a little cheaper something like this

[Ian PParticipant @ianp]

Jim

If you go the route of reducing the thickness of some extruded brass bar bear in mind that if you only take metal off one face the bar will end up like a banana.

I am not totally sure that brass sections are manufactured by an extrusion process (but I doubt they are drawn or rolled), either way best is to take an equal amount of both faces.

Ian

[JasonBModerator @jasonb]

The biggest piece will be 15×21 so distortion over that is not likely to be an issue.

J

[Ian PParticipant @ianp]

Posted by JasonB on 05/01/2013 16:27:22:

The biggest piece will be 15×21 so distortion over that is not likely to be an issue.

J

True, (but in your original post you mentioned a strip 300mm long)

So, the finished part is you are making is 15x21x4mm, If you used 5/8" x 3/16" stock there would not be a lot of waste.

Ian

[1Participant @1]

Thanks for the continuing interest. I had planned on slightly changing the design of the straps to form them each from a single piece of metal and avoid the need to solder. However the thickness still has to be 4mm to fit the already made eccentric sheaves. Jason, if I could produce what you have shown in your link I would be a very happy bunny indeed but I need a heck of a lot more practice to get anywhere near that standard.

I hadn't realised that there would be a warping effect from taking metal from one side only of a bar and as the overall length of my straps will be 43mm I will watch out for it. My need for a 300 mm strip was to allow me to clamp the material at the ends and still make 2 straps and have the luxury of 1 scrap.

I have now ordered a 3/16" bar from Macc Models.

Jim

[Clive HartlandParticipant @clivehartland94829]

I have always annealed brass extruded materiel, it then does not bend when machining one side.

very simple to do, heat to a red colour and quench in water. If in doubt do it again.

Clive

[Sub MandrelParticipant @submandrel]

I made two straps recently that needed to be very thin (less than 1/8&quot. I made them from 1/8" material then milled them to thickness by carefully clamping them to the bed of the mill. This also allowed me to compensate for small errors in positioning the clamping screws and get them dead central.

I find that getting the outside of the strap perfectly round is helped by making a very short stub mandrel to fit the eccentric strap with a round clamping piece. This can be held on a chuck fitted face up on a rotary table and allows the machining of quite delicate straps.

Neil

[David LittlewoodParticipant @davidlittlewood51847]

Bright drawn mild steel (BDMS) – i.e. the normal stuff we buy – often has hoop stresses and can also suffer from bowing if machined asymmetrically. It can be cured by annealing – can't remember the recommended temperature, it's about 700 degrees C – and cooling slowly, before machining.

David

Edited By David Littlewood on 05/01/2013 23:52:43

[Ian S CParticipant @iansc]

I made the eccentric strap for my over haul of a Stuart Turner S 9 from cast iron obtained from an old car brake disc, looks OK, works OK. Ian S C

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