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Post by Deleted on Oct 15, 2008 22:43:16 GMT
I've mentioned that this is my first loco. Making coupling rods has tested all of my long forgotten 'time served' machinist skills, but it has been great fun. I'm sure it's not an original idea, but I made some brass sizing discs to help with the machining process: failing eyesight notwithstanding. I followed LBSC's advice and hauled the chuck round by hand: worked a treat! Flutes next.....  |
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Post by AndrewP on Oct 15, 2008 22:55:54 GMT
Neat, I bottled out and used filing buttons. Haven't plucked up courage to flute them yet - pictures please!
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Post by Deleted on Oct 15, 2008 23:11:31 GMT
Andrew: do you have a vertical slide or a milling machine? The approach will be quite different for each. If you would like any specific advice just send me a pm: glad to help.
JB
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Post by drumkilbo on Oct 15, 2008 23:34:58 GMT
Any advice and detail on this operation would be most welcome by me as well. Of all the procedures involved in building a loco I personally found the coupling rods the most awkward things to get right. Straight bits , nae bother, round bits nae bother, but round bits on the end of straight bits always give me a problem.
Ian.
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Post by AndrewP on Oct 16, 2008 13:52:38 GMT
JB; Thanks, I have both a vertical slide and a (small - X1) mill but am more likely to use the mill - there is a little less slop in it than my 40+ year old lathe.
Thinking about it I suspect I would drill a piece of heavy angle at the rods hole centres, clamp that down to the table set parallel and bolt the rod to it.
A woodruff key cutter (which I don't have) presumably for the slot because it would give me the sloping lead in that looks so nice.
Rob Roy doesn't call for fluted rods but what the heck - I like the look!
Cheers, Andy
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Post by Deleted on Oct 16, 2008 14:02:22 GMT
'That will do nicely' as the lady from Amex once said to me. By the way, you don't need a Woodruff cutter: I used a 1" x 1/8" side and face cutter on a home made 10mm arbor. You get a nicer finish because the woodruff is designed for hacking down into prop shafts! Just pass it down successively, and any slight tracking marks in the slot can be easily polished out.
Best of luck
JB
PS:Try and set up some end stops or put clear marks at the ends of the slots: finishing in the right place can be tricky!
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Post by Donald G on Oct 17, 2008 19:21:58 GMT
Simplyloco, thank you very much for the hints on the best way of fluting rods as that is one of the next major jobs I have to do for my Class 2 standard tank loco. Do you, in order to get the tapered flute, make the location at one end of rod so you can drop it enough to get the taper required.
Thanks for any advice on this job which I am not looking forward to considering the time spent making said rods.
Donald G
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Post by Deleted on Oct 17, 2008 19:59:01 GMT
Donald G, thanks for the nice words but please don't take my advice as gospel, there are many people with much more experience in these matters than me. I just take a production machinist's view and get on with it best way I can! I have yet to make the tapered connecting rods, but I won't be worrying about rotatable locations etc. An oversize mounting hole or slot would be used for the movable end.
For non-critical work such as this I would use a sticky pin (household pin stuck to quill with Bluetak). The sticky pin lines up the cutter onto the marked out lines: it is surprisingly accurate. When the taper is complete, I would use a lever type DTI to set the rod parallel with a fluting cutter, cut my flute, and do the same for the other side of the taper. I would then thin the rod using a slot drill/end mill set sideways. That's my thinking anyway, but I would not claim it to be the best, and I reserve the right to change it as I go along!
Best of luck
Regards
JB
A few people have asked me to continue with the Brit Progress posts: this I will do, but please don't shoot me down in flames if (and when) I get it wrong sometimes!
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Post by Donald G on Oct 17, 2008 20:26:36 GMT
Simplyloco, thanks very much for the advice, and I will shortly try to machine a tapered rod, maybe with a trial piece of steel to check operation first.
I have read before about use of a sticky pin, but have never actually tried it, so I will give it a go.
Many thanks
Donald G
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Post by Deleted on Oct 18, 2008 22:20:42 GMT
I thought I'd introduce the idea of stops to the few who may not be familiar with them. As model engineers we tend to think in terms of one-offs, but if you have, say, six keepers to make as I did today, then a simple stop will ensure accuracy and speed up matters considerably. Here I'm using a toolmaker's clamp as a stop: the keepers have already been machined one end, and are now being brought down to size after being placed against the clamp jaws. Easy peasy! JB  PS: I WILL finish the coupling rods this week! |
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