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Post by Deleted on Dec 14, 2014 13:16:41 GMT
Morning Alan, I will definitely relieve the outer flange but I'm leaving that process until I get all of the axles in place. I've noted that you've mentioned the inner flange before, so will bear it in mind! Roger machined his flanges, but I notice you mention more of a curve - would you usually do that by hand? A little fettling by hand should be fine....i did all my axleboxes so far that way and is how Don has advised for Doncaster....makes sense to do it that way to me as IMHO you have a little more fine control for achieving a running fit for each axlebox especially if you don't have access to CNC or even a DRO set up . Pete
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Post by Rob on Dec 14, 2014 21:21:44 GMT
Pete, that makes things easier! Interesting you mentioned the DRO, I was just thinking this afternoon how handy it is to have one. I was using the position storage feature, which automatically adjusts itself based on where you set your absolute zero points. Made drilling and reaming my remaining pin holes a doddle! Would be an absolute god send for something more complex with lots of holes! For some reason, I can no longer count to 12.
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Post by Deleted on Dec 14, 2014 21:37:31 GMT
' For now Rob I can only dream of owning a DRO.....maybe Santa might see my plight one day......hey I just watched 'Polar Express'.....I 'believe'.... so you never know....... Pete
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Post by Deleted on Dec 14, 2014 22:18:37 GMT
' For now Rob I can only dream of owning a DRO.....maybe Santa might see my plight one day......hey I just watched 'Polar Express'.....I 'believe'.... so you never know....... Pete What! Bed stops and slip gauges will be much more accurate than a cheapy DRO on your average dodgy compressed rice paper milling machine! John
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Post by Deleted on Dec 14, 2014 22:58:12 GMT
' For now Rob I can only dream of owning a DRO.....maybe Santa might see my plight one day......hey I just watched 'Polar Express'.....I 'believe'.... so you never know....... Pete What! Bed stops and slip gauges will be much more accurate than a cheapy DRO on your average dodgy compressed rice paper milling machine! John I'd best to at least get myself a set of slip gauges then John, very basic tools here...... Pete
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Post by Deleted on Dec 14, 2014 23:08:22 GMT
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Post by Roger on Dec 14, 2014 23:26:56 GMT
You're far better off saving your money for a DRO with say 5 micron resolution or better. Slip gauges have their uses but it's a painfully slow way to set up accurate positions. Winding handles, or letting a computer wind them, to a scale position is a most productive way of rapid positioning. A well sorted lightweight machine can still produce remarkable accuracy if used intelligently. I have slip gauges and I'm perfectly capable of using them with 'old school' setups, but life's too short to waste on old methods when there are far more productive ways of achieving the same thing.
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Post by vulcanbomber on Dec 14, 2014 23:40:05 GMT
Slips can do alot more than a DRO, in industry, time is money, as a hobby, money is time.....
I'd get slips.... then a DRO...
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Post by Deleted on Dec 14, 2014 23:42:26 GMT
You're far better off saving your money for a DRO with say 5 micron resolution or better. Slip gauges have their uses but it's a painfully slow way to set up accurate positions. Winding handles, or letting a computer wind them, to a scale position is a most productive way of rapid positioning. A well sorted lightweight machine can still produce remarkable accuracy if used intelligently. I have slip gauges and I'm perfectly capable of using them with 'old school' setups, but life's too short to waste on old methods when there are far more productive ways of achieving the same thing. The DRO scale resolution is one thing, the translation through the winding handles is another! I'm just mean and old fashioned... John
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GWR 15xx
Dec 15, 2014 7:34:24 GMT
via mobile
Post by joanlluch on Dec 15, 2014 7:34:24 GMT
Hi guys. Just a very simple question. What DRO stands for? Thanks.
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Post by Roger on Dec 15, 2014 8:45:14 GMT
Hi guys. Just a very simple question. What DRO stands for? Thanks. Hi Joan, that means Digital Read Out. I don't really understand the argument of Slips over DROs, they don't really solve the same problems. Slips are the ultimate reference and can be useful at times. If I didn't have any slips, I wouldn't really miss them, if my DROs broke I'd replace them immediately. Because they measure the actual position of the table or carriage, backlash isn't an issue any more. You also don't have to keep track of how many turns you've wound the handles or carefully trying to zero a dial without disturbing the leadscrew. If you've not used one, you don't know what you're missing. They are one of those things that you think you don't need, but won't live without once you've had one.
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Post by ejparrott on Dec 15, 2014 9:14:37 GMT
A DRO does one thing, on one machine. Slips have a multitude of uses and can be transfered from bench to lathe and back again. If money is the driving force, then get slips.
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Post by Deleted on Dec 15, 2014 10:05:21 GMT
When I was machining axleboxes for Halls and 28xx at B'north on the jig borer, after the finishing size cut for outer flange thickness we'd put a scrap power-hacksaw blade between the angleplate and top of the box ( for about 1 to 2" insertion ..... This would slew the box over a minute amount ( Roger, a minute is just a tad bigger than a micron, whilst a tad is 0.75 of a Nudge --- Ho-Ho !!)...and run the cutter along again, the idea being to relieve the top and bottom thrust faces by approx 1/3 each of the total length....As the saying goes}----"It's horses for courses" only these "Horses" weren't running on the GWR smooth "course" anymore but on a Heritage Railway's roller coaster ( By comparison that is.....The P'Way guys are doing the very best that they can----)
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Post by Rob on Dec 15, 2014 23:23:39 GMT
Some more work with CAD this evening. This was entirely academic as my cylinders have a large void cast in the back, but if I had the option of machining from the solid or drilling my own exhaust ways, this is how I would have done it: This would be as machined, the two exhaust passageways combining into a larger opening the same diameter as that in the frame. Then, by hand, I'd blend the edges for better flow: So ultimately, it'd look like this mated to the frame: The blending is probably little much with this example, and the 3D rendering doesn't really illustrating it very well as it looks like there are still some sharp edges even though there aren't, but it's only a rough idea! In my opinion, this design would promote the best exhaust flow. I'd also match the inner diameter of the blast pipe to the frame/cylinder exhaust size diameter. Anyway, as I mentioned it was largely an academic exercise as I don't have the option with my castings . I added the ports initially as another way to double check my frames and cylinders are drawn correctly - the ports line up as they should, so I'm a little happier!
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Post by Roger on Dec 15, 2014 23:30:12 GMT
The thing I'm annoyed about is that I forgot to add the fixing holes for the blast pipe tubes to the frames and I can see that you don't have them there either. I like the look of the gussets, they're excellent. I noticed that two of the SPEEDYs at the show had countersunk holes on the outside of the frames, presumably to allow for the gussets to be fitted on top. Are yours going to be purely cosmetic or are they structural? I take it you've checked the buffer head diameters, they're too small on the plans.
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Post by Rob on Dec 15, 2014 23:53:08 GMT
Hi Roger, Well spotted, I shall have to add them in. I'm lucky in a way as I have yet to set up the frames in the mill to re-drill all the holes missing from the frames drawings, so it's no bother to find those missing at this stage. I'm going to do the same with the countersunk frame holes as i'll still have inner angle pieces, too. I'd like to make it "structural", but it all depends on the room I have left once the frame bolts are in. The bolts attaching the gussets to the buffer beam are 8BA, and they're very close to the edges. One the model, the bolts will be reversed so that the bolt head is on the back with the nut at the front, but I think that it's going to be very very close with the fillet at the base of the gusset! I put structural in speech marks as i think it's doubtful they'll add much strength considering how small the bolts would be, but every little helps I suppose! To be perfectly prototypical, I'd rivet the gussets to the frames, which might be nice to attempt if there's space for the holes! Buffers are to correct scale size too
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Post by Deleted on Dec 16, 2014 0:06:21 GMT
and will that be hot or cold riveting ??
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Post by Rob on Dec 16, 2014 0:21:01 GMT
Lets pretend I have a mini forge, a tiny set of tongs, some help and an air hammer
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Post by Deleted on Dec 16, 2014 1:23:25 GMT
that should be fun to see on you-tube then ? ............. this might come in handy as well >>>>>>>>>
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Post by Roger on Dec 16, 2014 7:55:17 GMT
Sounds like a good plan. There's nothing to stop you from moving the ribs slightly on the gussets to make a little more room, I don't think it would show much. I'd still like to retain a short length of the large central bolt to hold on the buffer on if possible. I guess it ought to be possible to provide a shallow pocket for the nut in the back of the buffer beam and the same in the gusset to hide it. How are you going to retain the buffer head to stop it coming out?
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