jma1009
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Post by jma1009 on Mar 21, 2016 22:29:12 GMT
Hi Pete,
I would press fit a pin rather than a grubscrew, much less work! Yes make a deep file groove on the axle first otherwise the drill will wander into only the cast iron.
cheers, Julian
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smallbrother
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Juliet
Mar 22, 2016 8:32:33 GMT
Post by smallbrother on Mar 22, 2016 8:32:33 GMT
Will do!
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Juliet
Mar 22, 2016 21:29:57 GMT
Post by runner42 on Mar 22, 2016 21:29:57 GMT
Hi Pete, I would press fit a pin rather than a grubscrew, much less work! Yes make a deep file groove on the axle first otherwise the drill will wander into only the cast iron. cheers, Julian Hi Julian,
I assume you mean that the groove is made along the bearing part of the axle and not on the end face, if so this has to be done before the wheels are fitted. Would a centre punch mark on the end face of the axle adjacent to the wheel be sufficient to keep the drill from wandering into the cast iron?
Brian
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jma1009
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Juliet
Mar 22, 2016 21:44:00 GMT
Post by jma1009 on Mar 22, 2016 21:44:00 GMT
Hi Brian,
The groove is made in the axle steel on the length that the wheel seats on (not the bearing part).
A centre punch mark will not be sufficient.
Cast iron is much softer than steel when drilling. So the drill wanders off the steel side.
Just an old tip given to me by the late Bert Brock 33 years ago when I was doing my first sets of wheels!
Cheers, Julian
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smallbrother
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Juliet
Mar 23, 2016 8:28:47 GMT
Post by smallbrother on Mar 23, 2016 8:28:47 GMT
Would a triangular file be the best tool for this? I assume a groove about half the depth of the wheel would suffice. (Measured along the length of the axle.)
Pete.
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Juliet
Mar 23, 2016 9:03:48 GMT
Post by Roger on Mar 23, 2016 9:03:48 GMT
Hi Pete, You have a milling machine, so why not get a ball nosed cutter and machine a slightly under sided groove in the right place? I put a groove on each end like that. This is the setup I used, the square and carrier on the end helped set them at approximately 90 degrees. 20140322_171010 by Roger Froud, on Flickr
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smallbrother
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Post by smallbrother on Mar 23, 2016 9:39:47 GMT
Hi Pete, You have a milling machine, so why not get a ball nosed cutter and machine a slightly under sided groove in the right place? I put a groove on each end like that. This is the setup I used, the square and carrier on the end helped set them at approximately 90 degrees. 20140322_171010 by Roger Froud, on Flickr Hi Roger, I am looking for the cheap and cheerful option! Whilst following your procedure would be good training if I ever get to build something bigger, my aim is to get this loco complete, certified, run it round the track a few times and that is really that. It won't be needing measures to ensure parts don't wear out. I mean no disrespect to the design of loco, previous skilled builders or anything like that. It is a beginners loco and that is what I am for sure. I am beginning to appreciate the difference between my Myford ML7 and the Warco mini-mill, which cost about the same (£750ish). The Myford removes whatever amount you move the handles by, the mill seems to have a mind of its own sometimes. I think it needs stripping and sorting and I have an article to guide me through this process. All part of finding my way in this hobby! Please keep the advice and suggestions coming. Pete.
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smallbrother
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Juliet
Mar 23, 2016 13:02:04 GMT
Post by smallbrother on Mar 23, 2016 13:02:04 GMT
I have raided my wife's photobucket account as I couldn't get the IMG codes to match the photos on my own. Anyway, here are the axleboxes in the frames. Axles in progress. Wondering about doing the eccentrics! Is the 4 jaw in the lathe the best way to get the hole offset? Pete.
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smallbrother
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Juliet
Mar 24, 2016 13:48:14 GMT
Post by smallbrother on Mar 24, 2016 13:48:14 GMT
The eccentric for the axle pump has the usual slot for the strap. However, the drawing shows a sort of boss on the side of the eccentric which is used for the grub screw hole.
Any reason the grubscrew hole can't be made through the slot itself? I can't see the advantage of the boss on the side.
Pete.
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Juliet
Mar 24, 2016 14:04:15 GMT
Post by ettingtonliam on Mar 24, 2016 14:04:15 GMT
The great advantage of the boss to one side for the grub screw is that you can get at it to tighten it up, if necessary, without having to remove the eccentric strap first. Also gives a greater bearing for the eccentric on the axle itself. Yes, I know you can drill a hole in the eccentric strap, so that you can access the grub screw that way, but if there's room for a boss, that would be my first preference.
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Juliet
Mar 24, 2016 16:58:36 GMT
Post by GWR 101 on Mar 24, 2016 16:58:36 GMT
Hi Pete, and using the boss it doesn't need to be a grub screw so you can increase the screw size and use a different type. Regards Paul
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smallbrother
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Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
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Juliet
Mar 24, 2016 17:49:53 GMT
Post by smallbrother on Mar 24, 2016 17:49:53 GMT
Thanks for replies.
Do these things work loose often? I haven't had it happen on any of my regular running locos - not yet! (Touch wood).
Pete.
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jma1009
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Juliet
Mar 24, 2016 21:45:26 GMT
Post by jma1009 on Mar 24, 2016 21:45:26 GMT
Hi Pete,
That boss on the side of the axlepump eccentric is a pain to machine. Ive only done one this way (on a rather nice Colchester lathe) when I built my first loco. The 'thud thud thud' doing the boss is quite a shock to a smaller lathe.
There is no mechanical reason why your original suggestion should not be perfectly OK IMHO.
Cheers, Julian
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Juliet
Mar 27, 2016 9:20:47 GMT
Post by GWR 101 on Mar 27, 2016 9:20:47 GMT
Hi Pete, hope you don't mind me coming back to this but I was looking at the eccentric and drawing on my Juliet and just wondered why wanted to go down this route. Is it material availability or as Julian validly mentioned a machining issue, I don't have an issue with machining uneven shapes as my equipment is fairly robust but I do understand the issues.
However having said that the addition of the boss does also have a couple of plus points, it increases the contact length with the axle which I believe makes a superior fit as the standard width without the boss is only 3/8". Also there is the issue of holding the part to undertake the machining as the boss makes this simpler to undertake most of this in one setting. There are obviously lots of alternative ways round this including of course Rogers part on a stick method, any way good luck with your build. Sorry for the ramble, regards Paul
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smallbrother
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Post by smallbrother on Mar 27, 2016 17:29:07 GMT
Hi Paul,
Mainly it's about getting on with it as quickly as possible and recognising this loco is not going to be doing hours and hours of running.
I quite fancied machining the odd shape but if it isn't vital it can go without.
Pete.
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smallbrother
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Posts: 2,269
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Juliet
Apr 10, 2016 8:18:49 GMT
Post by smallbrother on Apr 10, 2016 8:18:49 GMT
Aaaargh. The axle pump eccentric seemed to be complete until I put it on the axle and it was out of square. the hole is about 10 thou out in half an inch.
I forgot to check the front face when I set it up in the 4 jaw and assume this has caused the problem. I made a deep hole with a centre drill first so I can't think of any other reason for the hole to have wandered off.
Any other possible things to check?
Pete.
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Juliet
Apr 10, 2016 8:34:16 GMT
Post by Roger on Apr 10, 2016 8:34:16 GMT
Hi Pete, I'm afraid that you can't rely on any chuck to hold square, and the shorter the thing you're holding, the worse it gets. It can take ages to get something square in the 4-jaw, and when you've done that, you find that it's not central any more!
I'd mark out the centre for the eccentric and accurately centre pop that. When you set it in the 4-jaw, get that close to the centre with a wiggler (an extended sprung pointer that exaggerates the error), then start clocking the face. Try to keep only a slight pressure on each jaw, protecting the job with paper between the jaws and the job. You can sometimes go round in circles, tapping the high point and never get it right. One way round this is to use a lever behind the low spot to gently bring that forward, protecting the job with cardboard so you don't mark it. It can be a painfully slow process, but worth the effort. Once it's really close, check the centre position and gently go round, tightening the jaws, checking it's square all the time. With patience, it's possible to get it spot on.
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smallbrother
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Juliet
Apr 10, 2016 8:47:13 GMT
Post by smallbrother on Apr 10, 2016 8:47:13 GMT
Cheers Roger.
I have bought some more bar so I can make a few more cockups as I practice!
Pete.
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Juliet
Apr 10, 2016 9:04:15 GMT
Post by GWR 101 on Apr 10, 2016 9:04:15 GMT
Hi Pete, you haven't said if you went for the boss design ?. I assume the rest of the eccentric is finish machined and all true within itself, if that's the case and you didn't want to make another you could set it up "true" in the lathe and open the bore out and bush it. Just a thought, easy to say but it's all part of the learning experience, and as they say "those who haven't made scrap haven't made anything". Good luck Paul.
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Juliet
Apr 10, 2016 9:42:46 GMT
Post by Roger on Apr 10, 2016 9:42:46 GMT
It's all good practice, and I'm with Paul on the cockups, I make plenty.
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