Grates and things

[jma1009]

i have one of those welded stainless grates flogged by a few of the commercial ME suppliers... actually NCB washery sieve material originally.

the spacing isnt what i like as the firebars (although of nice 'V' section) are wider than the gaps between.

i was thinking of running an angle grinder along the gaps to reduce the width of the firebars so that they equate with the firebar thickness and gap width i prefer...

has anyone ever done this before and anyone foresee any problems? i am quite handy with an angle grinder using cutting discs.

cheers,
julian

[springcrocus]

Although I know nothing of the item you are describing, the only thing I can remember from my commercial engineering days is that grinding stainless steel is a ba***rd because it clogs the wheels something rotten. Not that I have seen it personally but there used to be many a tale of burst wheels from attempting to grind stainless by the unwary. Good luck, and take especial care...

Steve

[steamcoal]

Julian,

Is it like this? Looks like some filter mesh. Not much material in it and they seem to buckle easier than bar. Guess there is only 60% of the cross section anyway. Thats a bean size piece of coal.

.

You can see it buckling and the air gap is rather small to clear ash and cinders.


Something more substantial below.

[Roger]

Someone at the Crawley club swore by a grate made from steel plat with holes drilled thought it. I quite like the idea of that because you could use a centre drill to taper the holes from the bottom. You can also make it in any material you like, and I doubt if it would take much longer to make. Has anyone else tried these?

[Shawki Shlemon]

Yes I use one on the Rocket , it a matter of calculating the total area of holes verses the area of the grate , they are common here in OZ ( not like the bar grates ) .

[steamcoal]

Roger.

Ask the Aussies. They like those Rosebud grates. Made out of 1/2" plate with hundreds of holes drilled through 'em.

Hayden

[steamcoal]

Ya beat me to it Shawki.

[Roger]

Thanks Shawki, do you have a formula for those?

[Shawki Shlemon]

Roger , no you don't need a formula , what I have a chart in the workshop that I made , on it the areas of holes from 1/16 to 1/2" , the rest is simple depending what percentage of gap to solid is required , I use this chart for other purposes .

[chris vine]

Hi Julian,

The material you have can be called V Mesh or wedge wire screen and it is available from quite a few suppliers. Certainly you can get it in rather heavier sections than the ME suppliers usually stock. I got some and it is nearly indestructible!

I got it from these guys www.optima-international.co.uk/ who were really helpful. I can't remember if I had to pay for some small off-cut size bits or if they just put some in an envelope for me. I know that I cut out one grate to fit Bongo and then scribed round it on some other bits so I can cut out future grates. (The original grate was made from ME size wedge wire screen and buckled quite quickly.) The new version is much better.

This page www.optima-international.co.uk/specification-guide gives you some idea of the range they can do. You even get the choice of shape of the wires, let alone thickness etc...

Chris.

[jma1009]

hi Hayden and Chris,

yes, that's the type of stainless grate i was referring to.

all those of this type ive seen, and the example i have, dont have IMHO wide enough gaps between the bars. hence my idea of attacking my example with an angle grinder and thin cutting disc.

they came to prominence some years ago when the late Norman Spink acquired a load of NCB washery screens and cut them up as loco grates.

for UK coal i dont think you can beat the type of homemade grate pictured by Hayden out of bar. i have been on the lookout for some stainless strip 2mm x 10mm but so far my searches have been unsuccessful.

hi Steve - and thanks for your advice. i must admit ive never used an angle grinder on stainless before.

for grates ive always followed the SMEE standard of say 3/32" bars with 1/8" gaps, or 1/8" bars with 5/32" gaps for medium sized 3.5"g and 5"g locos.

cheers,
julian

[Jim Woods]

Hi guys,

The Bar grate Hayden showed I made for my Isle of Man loco. it is to the oridgional Mike Casey Drawings and Mikes Peveril is now 30+ years old and steams like a witch still burning what ever you throw at it. I run it last year at IMLEC. The rough air % is 60. I have looked at grate designs by LBSC, Evans, Young, Greenley and others over the last 90 years and this seems to be the favored sizes for 5 inch gauge and an amount I hear quoted quite abit. I works for me on my IOM loco Mona and I find with the welsh coal you need to rake out the ashpan every now and then, just like the big loco's to keep them clear. with "soft" coals you seem to be able to run a 50% air gap. I also believe that a good gap is important to allow the ash to drop through and stop clinkering.
the stainless strip was cut from 3mm 316 sheet in a big guillotine. the cross ties are 3.2mm (1/8) stainless welding rod, threaded on the endeds and stainless nuts. spacers are 1/4 stainless superheater tubes off cuts cut to suit the air gap required.
I think every loco is different, wide fireboxes vs Narrow, long vs short and so on. the ashpan plays a lot too with how the fire reacts. where the air comes in, the amount of air, like a carburator I guess. And of course the heating area and front end design. many people have worked all this stuff out, but no one formular will suit every loco, big or small it seems. I use to look after 2 New Zealand Ab class steam loco's. these where 4-6-2 tender loco's running what was called the "Kingston Flyer" only a few numbers apart and should have been the same in performance, nope! 778 was happy with 4 or 5 cars pulling up the grade while 795 would sulk with a light load and you had to chase it along with the blower all the time. however 8 cars full regulator, about 50% cutoff, steamed great while 778 would lie down and have a snooze while having a boil up. go figure. the only thing I found was that 778 had a liner in the chimney so mabe it was too choked. The owner wouldn't let us remove it to find out.
I think this is where IMLEC is great to find the optimum settings to get the best out of your loco. be nice to see if Lional Flippance ever builds his other boilers for the 2-8-2 to see what he can do.

thanks

Jim

[mattscrutton]

I used to have quite widely spaced bars on my Midges old grate. I replaced that with the stainless washery stuff, absolutely no difference in performance. In fact I think it improved as the fire became slightly deeper.

[mattscrutton]

Oh as a quick aside Julian, Model Engineers Laser supplies it with two different bar spacings.