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Discussion in 'Workbenches, including workshop techniques.' started by Martin Shaw, 28 March 2020.
I’ll try that...
quite impressive. That's after some two minutes. I wonder where all the material went. Nothing to see in the tank.
I have to say I didn't expect that.
Mine is currently emptied so I can't try the party trick, but it does give you food for thought.
If the ultrasonic cleaner erodes whitemetal does it do something similar to solder, or some solders, as the alloys can be similar?
I pondered that as well, Fraser, but in the end decided 'probably not'.
For a start, I do use mine for cleaning electronics occasionally and haven't yet had a problem there. The other clue I think is in the patterns of erosion in whitemetal - I can't be sure, but it looks to me like the cavitation is pulling out micoporosity in the whitemetal. In soldering I think the specific application of heat to the metal reduces the porosity in the material.
It's a theory anyway...!
Michael’s piece of foil looked to be quite smooth before “treatment”, whereas mine was ripped off the end of the roll, as a result, slightly crumpled and roughly flattened. It’s not even slightly scientific, but I’d suggest that the erosion on my piece is strongest where there was either an edge or fold, or had been, but it had been smoothed a bit. There is some evidence of the edges of Michael’s sample being eroded.
“Stress concentrations“ seems plausible...
“Grain boundaries” likewise, perhaps?
Then the question arises, does the erosion happen preferentially on points & other convex features, or in cavities?
My guess is the latter.
And, could such a phenomenon be useful?
I'm not having a good week, I have managed to break two drill bits whilst attempting the drilling of handrail holes in the brake van, one on each side, and to add to the general b****ration factor neither has enought stub to be got hold of. With it being whitemetal the cope for surgery is limited, and generally I not overly happy with it anyway so I feel this one might go back in the box under the workbench for another time. I don't know whether it's an age thing but I seem to be finding things harder to do than years ago.
I recall there is a chemical method of attack for steel in whitemetal - dissolves the ferrous but doesn’t damage the model.
Unfortunately, I don’t recall what it is...
sorry this is not more helpful...
I think you may mean alum, I've heard of it for sorting out snapped taps before. I'm going to sleep on it, a cunning plan is forming.
Citric acid - available in powder form from a grocery supermarket.
Wikipedia likes Alum. Alum - Wikipedia
Citric acid also makes good flux. Wilko stock it, amongst others.
Thanks Brian, it's worth a try at the very least and somewhat easier than my illformed plan.
I had a look back to when I improperly used citric acid - definitely not to my advantage - but it could be good for your broken drills.
After leaving a loco headstock in a citric acid solution for a couple of days, all my lovingly crafted steel hex head bolts disappeared. This was 14 years ago and that project has remained dormant since.
There are more before and after photos somewhere, but found this one of a bolt head taken before the mishap - when I was trying to release some 'vitrified' flux from silver soldering.
The replacement castings for the N15 have arrived, the smokebox door needed some work so it sat centrally and was glued on yesterday with the dart added today. The rest will go on over the weekend, for which the weather forecast suggests indoors will be the place to be. The brakevan has gone into temporary hibernation while I summon some enthusiasm to move it forward.
Therefore what to do next, no shortage of options and I decided on something relatively easy, at least at first appearance. I'm rather fond of this, can't put my finger on why, perhaps it's the colour.
This is yet another coarse wheeled model with outside third pickups, and the principal tasks are, rewheel with finescale wheels, two rail it so pickups, a diet to remove the excess ballast, and some titivation to the bodywork. Taking the body off reveals,
a Crailcrest motor with twin drive to all axles, we've been here before with flexible couplings and it was painful then, though to be fair this is reasonably put together. It's a bit noisy, one bogie has gears that grate but it does run well enough. The lead pieces were what came out of the cabs, along with the glazing which is yellow with age. As can be seen its well coated with old oil, general muck fluff and what have you from the last 30 or more years.
Since I've now got the ultrasonic kit and mindful of the previous experience I was judicious in application and a bogie was cleaned,
A lot cleaner and with quite a bit of paint removed as well, it was already planned that the "chassis" would need repainted. The other one and the basic frame was also done, certainly a lot quicker than by hand. I am going to resist the temptation to strip it all down, one bogie at a time seems sensible. The next job will be the B end bogie strip to see whats worn and can sensibly be sorted, and also see whether anything needs ordered, I have wheels and axles so there shouldn't bee much, two sets of horns at the moment.
That looks a quality drive. The noise is probably coming from the spur gears, and it's surely worth trying to get working properly. I have a couple of these from resin kits which I'm looking forward to building...
Yes it always was pretty good and what Frank latterly put in the big leccy and diesel locos. There was also SR 10201 and a class 58, and along with 20003 they would pull the side of a house down. I'm never going to need that capacity so most of the lead can be dispensed with.
I've stripped a bogie down and made one or two discoveries,
the wheels are on extended axles, on the outer ends of which the dummy frames ride in overly large holes in the cast axleboxes, not disastrous but not very good either. The main frame is all soldered together which makes the wheels captive, any hope of unsoldering the ends and resoldering whilst keeping squareness is pie in the sky and well beyond my capabilities, so
at the correct places, four at each end I will drill 6BA tapping size c/sunk on the outsides. The frame can then be separated and the frame stretchers tapped to suit, so long as everything is clearly marked I should be able to reassemble it with a chance of correct alignment. I can't see another better way, but if anyone has a thought it would be most welcome. Here it is set up for drilling tomorrow.
The other interesting issue is wheels, the coarse scale ones currently in it are correctly 28mm B2B. The wheels came in the stash of goodies but I had no axles so I got six from JPL with a correct FS 29mm across the shoulders. When the wheels are screwed on the B2B is 30mm which is at least partly due to the teflon insulating bush on one side. If I therefore put the new oversize wheels on the existing undersize axles I should end up at 29mm B2B, bingo and I wont need to source extended axles. It seems to good to be true, why not though, got to come out on top once or twice.
The ends were drilled and tapped, I did this as per the set up above which meant I could tap under power and at least half a chance the tap would be square to the work. I realise it's only 6BA but so long as you don't use to much thrutch, into brass it's ok. I then cut the c/sinks again in situ and it allowed checking the screw without altering things, saves a lot of time. This all worked out quite well.
so I took it out to the garage for heat to be applied. A gentle flame melted the end plates without disturbing everything else, and lo it fell to bits.
It all needed cleaning up. I've won a watch on the wheels, putting them on the old axles gives a consistent B2B of 29mm plus a gnats, the flange width is right on the narrow limit so I reckon it will be alright. The axles had an end float of about 3.8mm so I turned some collars that just slip over the axle ends and are retained by the side frames, which has more or less eliminated it front and back there is about 0.2 still on the middle, probably unnecessary. The frame was reassembled with the wheelsets and it runs nice and smoothly, and given the axle bearing is a tad oversized hole in the sideframe, is pleasantly pleasing. Despite my best intentions it was inevitable that the previous alignment of the frames would be lost and as a result the main drive shaft is tightish, I think the end bearings no longer align so they and there mountings will need some adjustment, I don't think I've lost any fundamental relationship between various parts of the drive train, or if so it's adjustable, I should be able to make it all sweetness and light in due course.
My cousin's daughter and her new husband visited from a distance yesterday afternoon, in the thankfully warm sunshine, on their way north on honeymoon, unfortunately their first choice of the Isle of Capri is currently a non starter so they've gone to the Isle of Skye instead so they can guarantee some rain. I wish them both good fortune and long happiness together.
I put the layshaft in the lathe and watched the free end describe an eccentric circle which explains part of the problem, the other issue is the construction of the bearings for it. They consist of a tube soldered into a hole in a piece of brass that is bolted through the bogie end frame with elongated holes in the bearing mount. I can see why it was done this way but it is hellish fiddly to adjust so I decided to make a fixed assembly and see whether that might work better. It will still need adjustment so the holes in the frame can be elongated slightly and with tapped holes in the bearing support it should make tweaking easier. I am waiting on a 4mm reamer and some small cutters however the first attempt milled from solid is alright
but obviously enough the hole is not central to the spigot, (there's a Pete & Dud sketch here which still makes me laugh), actually the hole is central but the holding down on the rotary table moved so the spigot is off centre. This would work in the loco ok but it annoys me. I've made a jig to fix the workpiece to, I'll picture it tomorrow, trips to the workshop at this time of night will be frowned on but it goes forward. On a gear meshing note I would value opinions as to how much free play to allow between the helical gears, is a fag paper enough?
After last nights post today I made two of the bearings and integral supports,
the jig is swung out pf the way whilst the rotary table is centred. The brass plug I made way back in the A5 thread over 3 years ago, goodness me where has it all gone. The jig is held to the table by the csunk screws into the T nuts, the workpiece is held by cap screws into the tapped holes. The one furthest away I decided a 5.5 hole was suitable for an M6 tap, it isn't. Then the centring in the Y axis was checked on the work
the X is far less critical so long as there is adequate material for the finished product. An initial cut was skimmed to see how it looked
looks fine to me. After much twiddling of the knob and a sore shoulder we got to here
and the bearing hole could be drilled 3.9mm in diameter.
Then the work was reversed on the jig and the whole thing done again and the middle waste taken off to give this
I won't cut and finish to size until after the holes have been reamed 4.0mm, it's easier to hold in the vice as is. The reamer should be here tomorrow.
Dependent on how the test fit of the new layshaft goes that's either one or two bogies worth, it seems to have gone very well once I had sorted out holding the work adequately, indeed the actual machining was a small part of the exercise. More next time.