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Post by ejparrott on Jan 18, 2015 9:57:22 GMT
Hi Roger,
The machine already has ball-screws as it was previously a CNC machine, hence why it's so right for me to do it. The CNC was dying on it when it's original motor came apart. Work deemed it uneconomical to repair and surplus to requirements so scrapped it. I've had both screws reconditioned, and they'll be good for a few years. It's got some SEM Servo motor's on it, 120V 1.1Nm, they're off a Bridgeport machine that I bought the CNC bits off, along with a Z axis which mine didn't originally have. It's having Centroid control, which ultimately I'm planning o control with a Tablet type device, so that programmes can be created in the house in the warm and then the machine just plugged in when I'm ready.
Hi Phil,
I was going to do the dowel holes while the material was still solid before cutting the middle out, and just in case the iron opened out, it's a lot of metal I'm taking out, although I doubt it will move.
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Post by Roger on Jan 18, 2015 10:57:42 GMT
Wow, you've struck gold with that then, I'd really like a bigger machine, but there's simply not room for one if I want to have all the rest of my kit. Those SEM servos are really good, all of the CNC machines I service from the old company have them. Ours used to have Amchem servo amplifiers but they stopped making them and wouldn't supply any details. In the end, I reverse engineered them and redesigned them on the same sized card to drop in as a direct replacement. I still repair those from time to time. It will be interesting to see what you end up with.
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Post by miketaylor on Jan 18, 2015 12:36:09 GMT
Ed,
"I was going to do the dowel holes while the material was still solid before cutting the middle out, and just in case the iron opened out, it's a lot of metal I'm taking out, although I doubt it will move.[/quote]
Sorry if I'm being a bit thick about this but I would have thought this was all the more reason to leave the dowel holes until after the main cutting was complete. Any movement can be checked and allowed for while the main cut is done and then the dowel holes made at the end through main body and keep would be spot on.
Mike
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Post by ejparrott on Jan 18, 2015 12:41:24 GMT
The problem will be holding the keep as a separate item within the body to drill it, rather than to hold it and drill it as a separate item on its own. I don't expect Iron to move anyway, this stuffs bloody hard in the middle!
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Post by fostergp6nhp on Jan 19, 2015 19:12:57 GMT
When you drill for the pins set it in the vice so the clamping force from the vice jaws is clamping the keep into the box. Also superglue can be very usefull stuff if you can position the bits quickly.
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Post by ejparrott on Jan 19, 2015 19:33:13 GMT
Hmm.. I'll think about it. I've been using the large back face as the datum for everything so far.
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Post by Rob on Jan 19, 2015 23:40:59 GMT
When you drill for the pins set it in the vice so the clamping force from the vice jaws is clamping the keep into the box. Also superglue can be very usefull stuff if you can position the bits quickly. That's how I did mine, clamped in the vice, though mine are a great deal smaller than Ed's.
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Post by ejparrott on Jan 27, 2015 10:16:31 GMT
Little bit more progress on the brake gear, this is for the handbrake. I subbed out the crank for this. I could have done it on the works mill, but it would have took me a whole long day to achieve by the time I'd set up the equipment needed, then took it all off again ready for a Monday morning. It seemed the more sensible option. It comes about because the crank from the handbrake to the cross-shaft is a double crank in effect, but also slightly staggered. Fabrication was I figured the easiest way. I had previously made the one half as it's identical to the single crank on the other side. I set up the crank on a stub mandrel in the lathe and used a bit of pressure from the tailstock to drive it, then skimmed down the boss to fit the hole in the crank... Then I made up another ring to replace the material removed.... So that when the three parts are silver soldered together, it'll look like it did before... I'll wait for warmer weather before I do the soldering though...Got quite a stack to do now too. I'm thinking there won't be much progress for the moment. Everything seems to be waiting on me getting the mill sorted out, odd bits of which I'm still doing here and there. It might be better to get on with the mill without distraction and get it up and running properly...then I can deal with the backlog of jobs, unless of course I get an opportunity. I'm planning to order the encoders on Friday (Payday!!!!) and then I can get the stub shafts and the covers made when they arrive and I know how big they need to be. After that, it'll really be time to order the brain and do some wiring..then we should be good to go
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Post by Jim on Jan 27, 2015 21:16:05 GMT
Very, very nice work Ed. I was going to suggest you pop out here to do the soldering in the warm sunshine but it's been cold and overcast for a couple of weeks now with sign of a change. Jim.
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Post by Roger on Jan 27, 2015 22:17:50 GMT
Lovely job Ed, very nice indeed. I do like bits and pieces like that, they look purposeful.
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Post by ejparrott on Jan 28, 2015 11:32:57 GMT
Thanks guys.
Need someone to make a decision for me...I keep changing my mind! The splashers need making up before I get too far advanced. They're fitted to the inside of the frames on this engine. Usual king of thing, radiused, flat side to them covering the backs of the wheels, but the twist is the upturned flange at the front where it bolts through to the frames. I'm thinking of a rolled band, trapped in a former and beaten over, then the flat back silver solder or TIG welded (if steel) on.
Question is, Brass, Steel or Copper?
They'll be 1/16" or 3/32" thick. Steel will have to be done hot, that's no problem. Got some Brass and some Steel...Brass I always find a worry...
Someone decide for me!
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Post by ejparrott on Feb 9, 2015 11:22:20 GMT
Went down to work for a few hours to make some studs for holding together the eccentric halves on Saturday. We've got a Hardinge Super Precision lathe and it's a brilliant machine for screw-cutting. Has a 5C collet nose built in, full screw-cutting gearbox for the leadscrew but a separate variable speed drive for feed. The leadscrew as a single position dog clutch reverse too, and all together makes it very easy, much easier than setting up the right change wheels - if I've got them. I bought half nuts from ebay..the seller has a sense of humour at any rate.... The studs are double ended and not threaded right through...assembly is a bit of a fiddle and I need to make or find some special spanners to do them up tight in the very limited space The fitted portion is 0.25" diameter, the threads are 0.236 diameter and 0.0394 Pitch, overall length is 0.9055 so that the stud only just protrude from the locknut, and the thread is 0.315" long, about the minimum I could get to allow the nuts to go fully up to the faces, and maximum length of fitted portion. Then while I was at it I made the other stud to hold the pairs together. Largely not required, the eccentrics are keyed to the axle in the correct place anyway, but I could so I did. Once I've found or made the spanners I can then turn the stepped diameters on them that retain the straps, and then I can split them and fit them to the axle...that's going to be fiddly.....
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wiltsrob
Part of the e-furniture
Posts: 279
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Post by wiltsrob on Feb 9, 2015 16:14:18 GMT
looking great EJ .. I had better get a shift on to keep up
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Post by Roger on Feb 9, 2015 18:30:54 GMT
Lovely work Ed, they look really good.
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Post by ejparrott on Feb 22, 2015 13:50:21 GMT
I managed to get a few hours in last Saturday before disappearing of to foreign parts for work. I have now machined the axleboxes so they have the split in them for the keeps, the keeps are indiviually fitted to each one, and the retaining dowels holes are now in, just the one photo Before anyone starts going all anti-CNC on my ass, yes I did use it, but this time it was essentially a glorified self act or power feed with a DRO. It's all straight lines in a position to a depth, so easily done on any cheap crappy mill you care to mention, beginner or expert. Wasn't a good start to the day...keep pins were supposed to 3/16", but I picked up the 3/16" + 1/64" drill instead of the 3/16" - 1/64" drill...3/16" reamer promptly dropped straight through the hole..as did the 5mm...so we're now at 5.5mm....took me a few minutes to work out as well....never mind. It doesn't really matter, nothing else is affected by it. One of the 8 holes has pushed off too, special dowel for that one hole will sort that out. All four 'boxes and keeps are also stamped with an identifying number, there's very slight differences between them, and from now on they'll be kept as a matched pair. As the weather's been so bad I've spent the day designing some tooling for making the splashers. In the end I decided to use the 2mm brass sheet I've got. I did consider machining from solid, but I'd need to make two sets, as each one is over 120 degree's, and at the best part of 2.5" thick, that's one hell of a piece of material! I'll make some form tools and flange the brass plate as the original one's steel (iron?) ones are. Oddly, the verticals seem to have been joined to the round bits with countersunk rivets. You can clearly see the flange, but no sign of any rivets at all. I'll most likely silver solder them together in any case.
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Midland
Elder Statesman
Posts: 1,871
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Post by Midland on Feb 22, 2015 14:06:46 GMT
Little bit more progress on the brake gear, this is for the handbrake. Ed I know this is from your much ealier post but can you tell me how you got those beatiful curves on the left end, particularly where the two arms join the main arm? Do you need this CNC stuff for this? And I might add, get it all so snmooth? Cheers David
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Post by Deleted on Feb 22, 2015 14:10:12 GMT
I haven't seen the splasher pictures but I wonder whether the full size ones are put together as separate bits with the fixing angles hidden on the inside ???
Some Hunslet ones are definately made this way . The fixing flange is a curved angle with the lower lip under the cover plate and the flat side is fixed to cover plate with curved angle on inside .
M
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Post by ejparrott on Feb 22, 2015 14:25:20 GMT
David, I subbed this one out, so it was done on 2 or 3 axis CNC. It's possible to do it manually, it just needs a bit more thinking about and a few bits of setting up. The round end is easiest achieved with a dividing head, setting the centre of the rad on the centre of the rotary table, then offsetting the milling cutter the required amount, and winding the rotary table around. If no table available, then a method I've seen suggested several times which I really dont like, is to set a peg in the mill of the table, or on a vertical slide if in the lathe, then literally by hand, feed the material around a cutter that is rotating....worries me about where hand might end up doing that!
Michael, these are made from two plates. The vertical plate is flanged over like a boiler plate, then the top plate with fixing flange is rolled, and a flanhe formed on it where it bolts to the frames....I'll upload a photo...
BRB!
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Post by ejparrott on Feb 22, 2015 14:30:11 GMT
This is probably the best picture I've got of them
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Post by vulcanbomber on Feb 22, 2015 16:11:27 GMT
would a billet make 2 Ed if you turn them, drill them then plough the middle out? Or even from a bit of tube and solder this end piece on?
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