timb
Statesman
Posts: 511
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Post by timb on Feb 18, 2021 13:43:18 GMT
I bought some 1/4" square ground stock to use for guide bars. Juliet needs 1/4 x 3/16 so I milled off 1/16 fron one edge - result - a rectangular section steel banana. Try again - sat the steel in a kiln for an hour at red heat and cooled all day. Milled again - a banana with a rubbish finish.
What should I be using for these bars? I dont suppose they need to be hard, just not soft if you see what I mean.
Tim
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Post by John Baguley on Feb 18, 2021 13:56:29 GMT
I've always used ground flat stock of the appropriate thickness, sawn a strip off and then machined the edges. No problems with it warping then. I think you can still get rectangular flat stock in various sizes. There's a place in Sheffield I think but can't remember the name!
John
It may have been Sheffield Gauge Plate I was thinking of but there's plenty of suppliers listed if you do a search. I used to get mine from RS Components years ago.
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timb
Statesman
Posts: 511
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Post by timb on Feb 18, 2021 14:08:27 GMT
Thanks for the reply John,
If I understand you right I should buy some wider strip at the correct thickness, say 2" wide at 3/16" thick and saw a 1/4"+ in piece off to be milled to size?
Tim
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jasonb
Elder Statesman
Posts: 1,206
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Post by jasonb on Feb 18, 2021 16:08:28 GMT
You could try taking a bit off each side at a time, say 10thou one side then 10thou the other and repeat 3 times. Or start with black bar.
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Post by John Baguley on Feb 18, 2021 16:59:27 GMT
Thanks for the reply John, If I understand you right I should buy some wider strip at the correct thickness, say 2" wide at 3/16" thick and saw a 1/4"+ in piece off to be milled to size? Tim Yes, that's what I do. I use ground stock (gauge plate) for valve gear parts as well. It's no harder to machine than mild steel and any holes for pivot pins don't really need to be hardened. I use hollow silver steel pins for the pivots with a bolt through them to hold them in place.
John
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Post by Deleted on Feb 18, 2021 17:18:56 GMT
Hi Tim
I do as john and use ground stock (gauge plate) of the correct thickness and then machine the width to size. Gauge plate is very stable and a joy to machine, all of my motion will be from gauge plate except for the rods which are HRPO steel which also has no built-in stress.
regards
Pete
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Post by GWR 101 on Feb 18, 2021 18:48:31 GMT
Tim, I was lucky with mine I had some 1/4 sq. "key" steel and managed to take 1/32" off each side and it remained straight. I am not a metallurgist but believe that it is similar to EN8 so it is machinable. After a quick search of the web I did find a business in Stourbridge that stock 1/4" x 3/16" in 12 " lengths. so it must be out there. Hope this is of some help, keep up the good work. Regards Paul
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Post by coniston on Feb 18, 2021 23:30:39 GMT
You could try something like this, cut to length, cut width in half and clamp both pieces in the vice to mill to 1/4" wide. Pretty good price and what I've bought has arrived within a week.
Chris D
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timb
Statesman
Posts: 511
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Post by timb on Feb 19, 2021 8:47:05 GMT
Thanks all, food for thought.
Chris, were you referring to something specific as there is no link?
I have ordered some 4" wide 3/16 thick gauge plate with the view to milling the edge straight, hacksawing a slice off then milling to size - will let you know how I get on.
Anyone want to but 4 accurately sized 1/4 x 3/16 bananas at 3 3/4 long??
Tim
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Post by coniston on Feb 19, 2021 10:36:08 GMT
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timb
Statesman
Posts: 511
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Post by timb on Feb 19, 2021 11:52:35 GMT
Thanks Chris, thats exactly where I ordered it from!
By the way does your surname begin with D or is that a wide grin after the Chris??
;-D
Tim
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Post by coniston on Feb 19, 2021 21:54:44 GMT
Thanks Chris, thats exactly where I ordered it from! By the way does your surname begin with D or is that a wide grin after the Chris?? ;-D Tim Nothing as clever as a wide grin I'm afraid, just surname initial (Dore)
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Post by jordanleeds on Feb 20, 2021 19:33:51 GMT
It is possible to straighten by heating and clamping. Effectively stress relieving the material
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timb
Statesman
Posts: 511
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Post by timb on Feb 21, 2021 12:49:20 GMT
It is possible to straighten by heating and clamping. Effectively stress relieving the material I did actually try this and left the bars in my muffle furnace at red heat for about 4 hours. I checked the following day after cooling and they were still bent!
Tim
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Post by 92220 on Feb 22, 2021 9:06:58 GMT
Hi Tim.
When machining pieces of steel bar where the length is significantly greater than the cross sectional dimensions, the bar should always be annealed before any machining along it's length, otherwise it is guaranteed to bow. When I machined the motion parts for my loco, I annealed all the raw materials in an old barbecue, keeping it red hot, and heaped with charcoal, for around half an hour, and then left it all to cool down overnight. Nothing bowed during machining.
Bob.
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mbrown
Elder Statesman
Posts: 1,713
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Post by mbrown on Feb 22, 2021 11:00:25 GMT
Take care though! I tried annealing some steel bars in the fire of one of the Talyllyn locos, reasoning that they could lie all night in the embers and cool slowly. I put them in about half a mile before the end of the last trip of the day and by morning they had partially melted with burning on all surfaces....!
Malcolm
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Post by Deleted on Feb 22, 2021 11:52:53 GMT
As some will be aware, I'm currently milling my outside connecting rods. For 5"gauge, they don't come much longer (nearly 12 inches) or perhaps, much slender. I'm not expecting any issues with twisting/warping, I do believe that the best answer is in selecting the right material and how the piece is held. These particular rods are HRPO steel and thus no inbuilt stress in the metal. I have already machined the sides down to the required thickness with no problem. As far as setup is concerned, I bolt the rods to heavy lumps of steel, these, as well as offering a very rigid jig also act as a big 'heatsink' and thus again reduce any issue with movement due to heat.
All rods on 4472 are HRPO, the outside connecting rods that I'm doing now being the last to do. All other motion parts are in gauge plate which again is very stable.
On a side note, if there was ever a need to heat a part, I'd probably heat it and then fit it to the original jig to cool, yes it will cool quicker but should cool to its correct shape/dimention.
Pete
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timb
Statesman
Posts: 511
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Post by timb on Feb 22, 2021 17:14:07 GMT
Thanks GG, I had not thought of using pickled steel, I assumed that the pickling would harden the surface a bit as it is done hot. I will try the gauge plate as it comes but I think I might try HRPO for the connecting rods. Do you have a supplier to recommend??
Tim
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timb
Statesman
Posts: 511
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Post by timb on Feb 22, 2021 17:17:10 GMT
Hi Tim. When machining pieces of steel bar where the length is significantly greater than the cross sectional dimensions, the bar should always be annealed before any machining along it's length, otherwise it is guaranteed to bow. When I machined the motion parts for my loco, I annealed all the raw materials in an old barbecue, keeping it red hot, and heaped with charcoal, for around half an hour, and then left it all to cool down overnight. Nothing bowed during machining. Bob. Hi Bob, I assumed that gauge plate was annealed before finish ground as it would be impossible to grind it flat otherwise?
I have successfully annealed steel for connecting rods and con rods before when I have used BMS.
Tim
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Post by Deleted on Feb 22, 2021 17:46:51 GMT
Thanks GG, I had not thought of using pickled steel, I assumed that the pickling would harden the surface a bit as it is done hot. I will try the gauge plate as it comes but I think I might try HRPO for the connecting rods. Do you have a supplier to recommend?? Tim Hi Tim I was introduced to HRPO steel by Malcolm at MEL, he described why it was best for Doncaster's coupling/connecting rods. As I am now machining the last two rods and have suffered with no problems with the rest I have become a fan. Gauge plate is just as good and a real joy to machine, all of the other motion parts will be made in this material, some of which are very long and slender. Kind regards Pete PS: Funny how when I'm called GG it still brings back fond memories of days long past..
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