Most of the bits and pieces have arrived for this project, so I made a start on the machining today. I used 80mm dia aluminium rod to make the stepper motor support piece.
Most of the bits and pieces have arrived for this project, so I made a start on the machining today. I used 80mm dia aluminium rod to make the stepper motor support piece.
I am close to disassembling the Bolton 9, before gradually reassembling it in preparation for running it on air then steam. Most of the components have now been made. Most recently I completed the pipework associated with the Edwards air pump and the twin water pumps.
So now I am making a list of tasks which need to be completed when the engine is taken apart, hopefully for the last time before it is run. The list is not complete, and so far it runs to 3 pages. Mostly like fixing parts which interfere with each other, and freeing up tight bearings.
I will take some pics of the components.
I have not weighed the Bolton 9 triple expansion steam engine, but I would guess that it is 20-25lb. (weighed it. 25.5lb)
Access to the various bolt on bits and pieces has become increasingly difficult and tricky, and involves frequent repositioning of the engine.
I removed the bolt on base and that has improved the situation a bit.
Then I had a brainwave, thought bubble, inspiration whatever, and I tried a ball bearing turntable…. you know….. one of those Chinese restaurant middle of the table gadjets.
It is incredibly useful!
Here are some pics and a video showing it in place; just a demo of the engine at its current (unfinished) stage. I think that the turntable might become a frequently used tool for heavier models.
While finishing the triple expansion steam engine, I have decided on my next project. Actually, based on my past history of procrastination with the triple, I might even put aside the triple to start on this one.
Reading this article in “Model Engineers’ Workshop” gave me the inspiration to convert a rotary table to electronic control.
So I have commenced accumulating the bits and pieces…
And some items of kit. Each under $20AUD.
I have disassembled the rotary table, and ordered a 12/8mm coupler. I am waiting for the coupler before I start designing and cutting the main part to be fabricated which is the piece which joins the stepper and the table.
Also ordered a box to contain the electronics and switches. Havn’t yet thought about cables, joiners etc.
The triple expansion steam engine has been progressing, again. I started this project over 2 years ago, but I have taken many breaks, some prolongued. One break lasted over 6 months while I made some cannons.
I cannot remember when I made the Edwards pump for the triple, but it must be over a year ago. In the past few days I have returned to it, finalising the mounting to the engine, and joining the driving levers to the pump and the engine.
The Edwards pump creates the vacuum in the condenser chest. It is an air pump.
Attached to the Edwards pump are 2 water pumps, which return condensed steam as water, to the boiler. At least that is what I understand from the descriptions. It feels a bit odd, making these components before understanding what they really do.
So I am at the stage where I would like this project to be finished, so I can get on with other projects. It feels like it is close because there are very few castings remaining in the box. But I know that the entire engine has to be disassembled, and painstakingly reassembled, freeing up some of the tight parts so it will turn over more easily. Then the steam pipe hookups and valve timing. Then hopefully, a video of it running!
Now that I have replaced the stepper motors in the Boxford CNC lathe, (see “New steppers for an old CNC lathe”) I am considering whether I might replace the spindle motor for the same reason… that it has become less powerful due to the age of its permanent magnets. Sometimes I am aware that it struggles to keep up the revs while cutting.
Watch the YouTube video about the next generation servo motors. They use modern rare earth magnets. They are powerful, compact and precise. And not cheap. Stuart T, who has the same Boxford CNC lathe as me, has suggested that these Clearpath motors would be suitable replacements for the ageing Boxford spindle motors .
Harold Hall has written many articles and several very useful books about metalworking, using a lathe, using a mill, and much more.
Recently he has been posting videos on YouTube.
He is a very knowlegable, dignified, elderly gentleman. His books are precisely, beautifully written, and the plans and projects are excellent. I have made quite a few of the project pieces in my quest to learn as much as I can about machining metal.
I came across his Youtube videos quite recently, and have been enjoying them. One of them was about his grinding rest.
I made 2 of the HH grinding rests from plans in his book, and they have proved to be useful, reliable, and compact. Here is a photo of one of them.
The original HH plans specify that the footprint of the base is much smaller than I made it. This one is 200 x 100mm. The larger footprint adds some extra stability (IMO), and the slots permit the grinder to rest distance being easily adjusted. It is a bit grimy because it is used frequently. Polishes up quite nicely.
In HH’s video he mounts the rest on a metal plate, joined with a couple of switchable magnet bases. Here is a link to HH’s Youtube video.
And in case you are wondering what has happened to the triple expansion engine, I have been working on the reversing mechanism. The intermediate cylinder reversing curved slide would not fit into the available space, so I removed it, silver soldered in a new end, and ground it several millimeters shorter. Then reinstalled it. It is still a mm or so too long but I think that it will do.
Robert the Bruce was watching a spider making a web in the cave they were sharing, so the story goes. The spider tried 6 times to make a difficult connection, and on the 7th attempt, it succeeded. Robert, who had tried many times to become king of the Scots, was inspired to try yet again, and he did indeed become King Robert 1 of Scotland, eventually.
I thought of Robert more than once recently, when I was making an ER40 collet chuck for my CNC lathe. The particular collet chuck involved making a 2.25″ x 8tpi internal thread, a 50mm x 1.5mm external thread, and cutting an 8 degree internal taper. Not too complicated you say. I agree, but for the chuck to be useful, each step had to be extremely accurate.
I made 4 successive collet chucks until one was adequately accurate.
Chuck 1 actually went very well. Nice tight spindle thread, taper good, and external thread just right. But the chuck did not quite seat firmly. Could it be that the spindle thread (the internal one) was not quite long enough? So I cut a deep distal groove. Wound out the carriage. Oh shit! Forgot to clear the spindle thread. Totally destroyed it. The chuck actually fitted the spindle quite nicely, but with only 10% of the thread remaining, it was useless.
Chuck 2 was made in 2 pieces, on suggestion from Stuart T. The idea being that if there was any inaccuracy in the lateral runout, the piece with the taper could be adjusted. OK. Sounded sensible. Again all went well, but the spindle thread was not correct. For some reason the thread cutter seemed to make a new path about half way through making the thread. So the spindle thread was thinned excessively. But still tight. So I made the tapered half, and joined it all together. Fitted it to the lathe and measured the runout and taper. All good. Less than 0.01mm runout and perfectly parallel to 100mm from the chuck face. But. The next day I removed the chuck, replaced it, and did the runout measurements again. I did not need a gauge. I could see the wobble. Chucked the chuck into the rubbish bin. That thinnned out spindle thread was hopeless. But what caused the problem? The thread was CNC cut, and it should have been perfect.
So chuck 3. One piece again. All seemed to go well, but again the big spindle thread was wrong. Again there seemed to be 2 thread paths.
Then the penny dropped. The spider made the web connection. Robert got the throne and John saw the light.
The tool post had moved slightly during the threading! It had twisted a little, as a result of the T piece in the carriage slipping. F**K F**K F**K!!!
I replaced the T piece grub screws with more solid cap screws, and really tightened them. Then made another chuck. I must point out that each chuck was about 6-8 hours of machining, normally a very pleasant time. But by this time, I felt like that bloody spider in the cave.
One advantage of making 4 chucks is that each one was made faster, and with more confidence. This one was made in about 5-6 hours, including painting with selenium oxide to give it a black appearance.
It has a runout at the chuck face of 0 – 0.01mm (which might have been due to inaccuracy in the rod which was being measured), and a taper of 0.02mm at 50mm from the chuck face. It feels nice and tight when being screwed on. OK, Success. Eventually.
Next job, the throne of Scotland.
But obviously that slipping top slide on the CNC lathe has to follow chucks 1,2 and 3 into the rubbish bin. It will be replaced by a fixed, immoveable tool post.
My Boxford TCL125 CNC lathe was missing steps in the cross slide, with resulting inaccurate work. Obvious causes, like cutters not sharp, or gibs too tight were excluded. Changes in the stepper motor settings maybe helped a bit, but not enough.
Stuart T suggested replacing the stepper motor, since the machine is a 1985 model, and the steppers look original, and therefore the 32 year old stepper permanent magnets are probably not as strong as they were originally.
We had changed the electronic controls in the lathe 3 or 4 years ago, so it would work with a Windows PC, and Mach3. Mostly I use “Easylathe” for generating the G codes.
Stuart had a spare stepper motor in his junk box, and it was the correct size (Nema 23), but more powerful than original. So I swapped it, and missing steps disappeared. Hooray! A minor problem was that Stuart’s stepper had shafts at both ends, and I was not comfortable about cutting off the unwanted shaft end, and I had decided to change the Z axis stepper also , so I ordered some new stepper motors.
A carton of 3 motors arrived a few days after placing the order. They are made in China, and are nicely finished. Each new motor had 4 wires, whereas the originals had 8 wires each, but reference to the wiring diagrams quickly determined the connections. Total cost for the 3 motors was $AUD90, including postage, and now I have a spare.
A big advantage of the NEMA mounting system is that the motor mounting dimensions are fixed, so swapping motors is simple. More powerful stepper motors are longer, but the dimensions are all available online, and can be checked before ordering.
A simple CNC turning test worked well, so I am hopeful that this problem is fixed.
Yesterday I travelled to Ballarat, (Victoria, Australia) to a swap meet which was held on 22 acres at the airfield.
Most of the stuff in the thousands of sites, was junk from shed and farm cleanouts. However, despite rapidly walking up and down the rows, I did not quite cover all of the sites. My Apple watch indicated that I had walked 18km (11.2 miles) and much of that was carrying a backpack full of bought items, so it was no wonder that my ankles were aching at the end of it.
I was really only interested in the few sites which had tools from factory closures. But my eye was drawn to the very old Caterpillar crawler tractor, a 2 tonner, not too derelict except for a broken exhaust manifold and some rusted growsers. $AUD9500, so I kept on walking. Lots of elderly, old and antique cars, motor bikes, and vehicular bits and pieces.
The following photos show most of the stuff which I bought, and some prices (except for the ones which SWMBO must never discover).
I mulled over a Mitutoyo 1000mm vernier caliper in perfect condition for $AUD300, but decided that it was a wanted rather than needed item, and walked on.
The high pressure mechanisms are the most exposed, and easiest to access, and they were very tricky, and not yet compeletely installed. I dread to consider what the intermediate pressure ones will be like, buried in the middle of the engine. Then there is the valve timing. Help!
The crowds were down at this year’s Truck Show at the Geelong Showgrounds. Maybe the 38c weather prediction had something to do with that.
But those hardy souls who did turn up were treated to a feast of steam engines working on steam, and other antique engines popping away, as well as the magnificent trucks, tactors, and military vehicles. There was a superb display of radio controlled trucks and excavators, and unbelievable machinery created with Meccano.
My interest was mainly focussed, for some reason, on the full sized triple expansion steam engine, which is the prize display in the vintage machinery shed. it once powered a tug boat, and later a dredge on Port Phillip Bay. And the following photos and video, if it will upload, show the bits which were of particular interest.
Video of the big triple expansion engine working. Maybe not.
For those following my triple expansion steam model engine build, I have put it aside again. It is at the final assembly stage now.
Meanwhile, I am making some extra tool holders for the CNC lathe, and another ER40 chuck for the CNC lathe.
The ER40 chuck which I am currently using has an M5 shaft which is held with a drawbar, so I cannot feed work through the lathe spindle. Plus it sticks out of the headstock a bit excessively. So I have drawn up plans for a new chuck which I will fit to the lathe spindle and use the CNC to make the ER40 taper and threads. Pics will follow.
And I really need some extra tool holders for the CNC lathe. I have 5, but have material to make another 10. The material is high quality cast iron off a scrapped T&C grinder. I bought the grinder table cheaply (($AUD20 from memory) and have been gradually canibalising it over the last couple of years. I have cut up the remains into rectangular 30x80x40mm chunks and will make the tool holders in the next couple of days, SWMBO and weather permitting. Unfortunately there was insufficient material to make a long section, machine it, then cut it up, so each tool holder will have to be made separately.
Hot workshop, wearing only shorts and boots.
Today was my deadline to have the triple expansion steam engine assembled and working, ready to be hooked up to steam at the Geelong Truck show.
GSMEE (Geelong Society of Model and Experimental Engineers) has a display in the Vintage Machinery Shed at the show, with many small working steam engines and the odd IC engine running. Plus the Vintage Engine group has many full size engines running…. always a really interesting place to visit.
Another full day in the workshop would have just about had the triple in the display. Unfortunately, I lost a day having to get a dental root canal abcess reamed out.
Then the day before yesterday, I could not find the drag links for my triple. I had made them in early December, and I was sure that I had put them in the multi- compartmented box where I store all such bits. Despite thoroughly searching the box, at least 20 times, they were not there. Could I have put them down somewhere else in the workshop? So I searched the workshop. No luck. So I tidied the workshop, putting tools away, sweeping up rubbish, all the while searching. Still no luck. So I cleaned and searched my car, my bedroom, the living room, every where that I could concievably have left them. (OK, I did not actually clean the bedroom and living room, but I did search). I grilled my wife. Had she seen them? No.
So I slept on the problem. Next day was going to be hot, so at 7am I drove to the workshop (it is about 15km from home), and searched again. Still no luck.
So I searched the multi compartmented box for the 21st time. I knew that it was a waste of time, but I was seriously considering making a new lot of drag links and bearings, probably a 2 day task.
There were some tiny containers with tiny fasteners in the compartmented box. The drag links could not be them because they are too big, aren’t they…..??
The first tiny container, contained, you guessed it, the drag links.!! They were smaller than I remembered.
Age related loss of short term memory…..
I had to get that one off my chest.
The other thing that I wanted to mention, is a superb machining blog site. Actually, 2 superb machining blog sites.
The first is by Joe Pieczynski, who is a Texan who makes his living from machining. His techniques and teaching are really, very, excellent. Aimed mainly at an audience who are beyond absolute beginners. Do a Youtube search on “Joe Pieczynski”. Look at his video on machining ultrathin materials.
The second, I have probably mentioned before. An Australian machinist, whose videos and machining techniques have to be seen to be believed. Mainly with a clock making interest, but the techniques can be used by all of us. For some reason I cannot cut and paste his Youtube connection, but you will find it by doing a search on “Clickspring”. What is particularly exciting in Chris’s “Clicksping” is that he is soon to embark on remaking an Antikythera calculator. Watch it! You will be hooked.
This valve is the one which opens the steam supply from the boiler to the engine. Triple expansion sgeam engines require a minimum of 100 psi, and preferably 120-200psi. But amteur built boilers are rarely certified above 100 psi.
But compressed air gets to 120 psi with no drama. So guess what will power this engine until I get around to making a high pressure boiler.
So the on-off valve needs to be pretty solid, so it does not explode and send hot fragments of metal in all directions.
Here is the main supply valve as specified and built for my triple expansion steam engine.
It all attaches to the high pressure steam chest and cylinder.
Making the new valve rods, as predicted, took me an entire day. They required a high degree of precision, and being in stainless steel, not an easy material to machine, and quite thin and delicate, multiple stages in the machining.
But before I started on the valve rods I made myself a new spanner for the collet chuck on the CNC lathe. I had been using an adjusting spanner, which was continually going out of adjustment and causing angst. The tool merchants did not have anything suitable (46mm opening, and thin profile), so I made my own.
So then I got on with the new valve rods. Some end of day photos follow.
And thank you to those readers who responded to my whinge about likes and comments. I will continue this blog until the triple expansion steam engine is finished, and hopefully running. Not sure after that.
“Underbelly” has a particular resonance for readers who know what the Yarra is and that Collingwood is a place and not a British admiral.
In the instance of my triple expansion steam engine, it refers to the bits and pieces underneath the cylinder block. The glands which prevent steam leaks from the con rods and steam valve rods, the and valve rod guides. These unsung heroes of the steam engine have taken 2 entire days to make. And here they are….
I started to count the number of holes drilled and tapped in this view, but gave up at 100 and still not half way. This engine better bloody work!
I have decided to replace the valve rods which are made of brass, with stainless steel ones. That will take an extra day, which might exceed my second, self imposed, deadline. But if it does, well too bad.
By the way…. I am considering whether or not to continue this blog. It does take time, and is not free. If you read this and are not totally bored, the odd “like” would not go un-noticed. A comment would be even better.
Another 2 days in the workshop. Heaven.
I had made a worm drive and gear using an M14 x 2 tap, but it did not look the part, despite being functional. The problem was that the threads were sharp triangular and they did not look correct.
So I made a worm drive and gear using Acme specifications. The teeth have a chunkier squarish look. More authentic.
I ground a lathe cutter and used it to make the worm drive in gunmetal, and another identical thread in 14mm silver steel (drill rod). The steel thread had cutting edges formed, and when finished it was hardened by heating red hot and quenching. After hardening, a file would not mark it. I did not bother to anneal it, since it would be used only to cut cut brass or gunmetal. The hardened tool was used to make a gear in gunmetal. Unfortunately I did not take pictures of those steps.
It is looking interesting, Yes? And there are 3 spare handwheels. The rest of the reversing mechanism components were made several months ago. Almost ready to install them.
In a previous post I admitted to breaking a BA7 tap in the Edwards air pump of the Triple Expansion Engine, and being unable to remove it.
The hole being threaded was one of 4 to be used to hold a water pump to the air pump. It was 2.5mm diameter (i.e. pretty tiny)
I tried to grasp with pliers the fragment still protruding but it then broke below the surface.
I tried to break up the embedded tap, using a HSS punch, with partial but inadequate success.
I briefly considered drilling a hole from the other end, and punching in the reverse direction, but that would really have compromised the pump.
So I decided that the three remaining bolts would have to be enough.
A night sleeping on the problem.
Next day, with a fresh determination, I decided to attack the problem again.
I had some used carbide milling cutters 2mm diameter, and I was prepared to sacrifice one or two of them. So I carefully set up the Edwards pump in the milling machine.
You can see the three good tapped holes. The carbide milling cutter chomped away at the broken tap, and using gentle pressure, and ignoring the metallic screeches, the tap was broken up and most of the fragments came out. I was prepared to sacrifice the milling bit, but it seems to have survived this insult. The harder metal always wins. It was probably fortunate that the tap was carbon steel and not HSS.
Somewhat surprisingly, the tapped hole was in reasonable condition, and it accepted a BA7 bolt, although I will not be aggressively tightening this one.
The triple will not be finished by Xmas. No chance of getting into the workshop while we are looking after 2 grandchildren. So the new aiming completion date is Jan 6, in time to run the triple on steam at the Geelong truck show. If I don’t meet that deadline, the next access to steam will be the end of 2017. I really do not want to wait that long.
So the next component to produce out of a chunk of gunmetal is the water pump.
There are two cylinders in the water pump. The gunmetal castings appear to be good quality.
Most of the machining will be done on the mill. But I need a datum surface, and have decided that the attachment plate is the most appropriate.
When I get back into the workshop I will machine the rest of the pump parts.