Author Topic: Reinventing the Real.  (Read 2201 times)

Offline Jasonb

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Re: Reinventing the Real.
« Reply #15 on: May 28, 2022, 05:01:35 PM »
With the arrival of some additional material the build can now follow a more logical direction starting with the base.

As I said in the introduction the one supplied by Stuarts is little more than a rectangle with rounded corners and a bit of draft angle which only needs flattening on the bottom, skim cut off the top and a few holes added which does not give you much workshop time for your money as it should not take more than an hour to do.

I opted for aluminium as it's easy to cut and no more expensive than bright steel flat. I've not noticed any problems with my other models that use aluminium right from the early ones I made 30+ years ago like the Minnie which has several aluminium castings through to others with aluminium castings and the ones I have fabricated using the material. Even Stuarts have used it to cast the fluted column of the Williamson.

So starting with a piece of 12mm material it was sawn slightly oversize and clamped to the mill table on some packing so that three sides could be milled square to each other. I then drilled four hole 5mm which were later countersunk on the underside for M5 CSK socket screws. These holes were also counterbored from above by plunging with an 8mm 3-flute cutter to form sockets that spigots on the column bases will fit tightly into so they locate accurately. I also drilled and tapped M4 for the studs that will hold the cylinder cover in place and at the same time added a small hole to use as a datum at the ctr of the cylinder position that could be used to locate the base on the rotary table if using that to mill the half round.



The two areas of waste were hacksawn off and put aside as they can be used for other parts later on then the front face with it's half round was milled to size and the decorative moulding added firstly by cutting a rebate 10mm deep and then using a 12mm ball nose cutter to do the concave detail.



The straight sides were next, to make it easier I clamped a straight edge to the mill table and clocked it in so it was then an easy job to locate each side against this and machine at the same settings. First doing the rebate and removing some of the waste with the same straight 10mm cutter.



Then the concave with the 12mm ball ended one



You can always judge if you have had a productive session in the workshop by the size of the pile of swarf produced.



The completed base which to my eye has a much more interesting overall shape and the moulded edge looks a lot nicer than the rather plain original. Plus with materials at 1/4 the cost of the casting and a bit more time needed to machine you are getting better hours enjoyment per £  :)




Offline Michael S.

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Re: Reinventing the Real.
« Reply #16 on: May 28, 2022, 06:17:45 PM »
Hello,

I think this is an excellent foundation to start a beautiful steam engine! I really like the base plate. Keep it up!

Michael

Offline Jasonb

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Re: Reinventing the Real.
« Reply #17 on: May 30, 2022, 07:07:04 PM »
The only other casting that I decided to use was one for the cylinder, again this was a very good casting and only needed a light fettle with files before I could start machining and not forgetting to clean out any remaining core sand from the cast in steam passages.

Part way through doing the cylinder I realised that there was a way to machine the portface, bore and one end of the cylinder all in one setting which would ensure all are true to each other so would suggest that the cylinder is mounted in your vice with the port face up and the piston rod end of the cylinder just protruding from the side of the vice jaws not in the middle as the first few of my photos show.

I started by setting up the casting so it was as true as possible in the vice using some thin strips of aluminium between the jaws and casting to take up any irregularities and give a good grip. Not knowing if there may have been some hard spots I took a clean up cut with an insert face cutter.



All was well and I also used this cutter to clean up the two flat areas above and below the portface, the 0.8mm radius corner of the inserts leaving a nice internal fillet. Changing to sharp 6mm cutter the portface was machined to finished size, using a small cutter with a 60-70% stepover gives a good flat surface that you may not get with a larger dia cutter if the tram is a bit off.



There was also just room to get the 6mm cutter down the side of the portface to remove the protruding exhaust connection boss as I won't be needing that.



I then drilled and tapped for the valve chest studs. rather than the original six hole pattern I went with an eight hole one as that cleared the side inlet position I wanted to use rather than connecting the pipe to the steam chest cover which is a bit of a pain when it comes to setting the valve position.



Over to the lathe and with the casting in the vice now shown in the position it would be best to start out with  it was just a case of adding some packing under the vice to bring the cylinder ctr line up to that of the lathe and using a between centres boring bar to take the cored hole out to the required 25mm bore.





Without disturbing the cylinder in the vice the end of the cylinder that will have the piston rod can now be machined square to the bore by using a flycutter



Back to the mill with the recently flycut end clamped to the mill table the other end can be milled and the cylinder brought to the desired length.



Finally for now with the portface registered against the vice fixed jaw the cylinder ctr can be found and the holes drilled and tapped. I used six M3 holes at the bottom to take M3 CSK socket screws up through the end cover and eight M2.5 at the top for studs and nuts as they show.



I'll cover that exhaust alterations lather in another post.




Offline Admiral_dk

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Re: Reinventing the Real.
« Reply #18 on: May 30, 2022, 09:25:08 PM »
I like the way you keep several faces and axes aligned this way  :praise2:

Keep it coming Jason - I (and others) will be following  :cheers:  :popcorn:

Per

Offline Jasonb

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Re: Reinventing the Real.
« Reply #19 on: June 01, 2022, 08:23:39 PM »
Thanks for the comments

The entablature supplied with the engine is really the" wrong way up" as classic architecture would have the bottom smaller than the top so it flairs out much like the capitals at the top of a column. So a new one was designed to be the right way up and also have a recessed middle band and raised bosses for the bearing supports and column nuts.

I started by milling down some 5/8" flat bar to 15mm thick with an 80mm insert facemill and then used a 6mm split point stub drill to stitch drill out the waste, These drills don't really need spotting first and being short don't wander into the previous hole. Keep the bit of metal removed from the middle as it will get used later.



After milling out the rectangle the four sides where milled to profile, for th emid section I used a 6mm cutter with a 1mm conver corner radius which leaves an internal fillet for that cast look.



After that the various holes were drilled and the bosses machined with the same corner radius cutter, I used the CNC but if you were doing similar on a manual machine then I would mill the two rectangular bosses but counterbore for the round ones and loctite in four turned "washers" unless you want to set up for each one on a rotary table. You can also see on the far side of the cut out that there is a deeper section which gives additional clearance to the eccentric allowing it to sit closer to the valve chest helping to do away with the cranked valve rod of the original design.



The bearing supports start out as rectangles of aluminium from the same piece that the base was cut from, Milled at each side to leave the feet and then drilled and tapped for the bearing caps



A two flute carbide cutter specifically for aluminium makes quick work of this taking full depth passes of 1.5mm wide per pass.



A simple vice stop allows the two parts to be swapped over in the vice without the need to keep locating their position and a spiral flute tap removes the swarf from the blind taped holes



To make it easier to hold the bearing caps while they were machined I cut them on each end of a larger piece of material before cutting them off and cleaning up the cut with a quick skim of a facemill.



Before cutting off I spot faced for the fixings and also milled a shallow counterbore which will have a short length of rod loctited in that has been threaded M4x 0.5 metric fine for an oil cup.



I tend to use cap head screws during construction as they are quick and easy to screw in and undo multiple time s with a suitable ball ended driver. Here you can see them being used to hold the cap to the support while the bearing hole is bored. I have packing on each screw head so that the pressure is not on the crown of the cap which may distort it.




Offline Jasonb

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Re: Reinventing the Real.
« Reply #20 on: June 02, 2022, 06:53:40 PM »
The columns on the engine are quite a noticeable feature, the book just shows them parallel turned to 1/2" diameter from 5/8" stock leaving a small flange at each end and a not "embellish as desired" which I decided to take them up on

I started out with some 14mm rod, this was ordered as EN1A but was really nasty to machine and also had quite a pronounced spiral finish on the outside. If you look closely at the threads on the right they were tearing and I was not hopeful of getting a good finish on the long slender taper.



After reducing the top 10mm length to 11mm diameter I then changed setup gripping this short length in the 5C chuck and supporting the other end with a small rotating ctr held in my Boring head which was offset to allow the taper to be cut. Initial cuts were not good but after trying a few different inserts I settled on a CCGT insert with 0.8mm tip radius which seemed to give a reasonable finish.



Then driving by holding the top spigot I just hand filed the rectangular ring that I had left into a half round profile and also gave the columns a quick going over with Emery cloth to clean up the finish good enough for painting.



I cut off 4 pieces of 20mm square steel, faced one end and tapped it to suit the turned part of the column then the other end had a spigot turned to closely fit the counterbores in the base before drilling and tapping M5. After this I milled 1mm off each side leaving 3mm at the bottom and 2mm at the top the full 20mm size. This was done with an insert endmill with 0.8mm corner radius tips  which once again left an internal fillet for that cast look.



The piece of aluminium that I stitch drilled out of the entablature was milled down to 15mm square and the capitals machined from that using a form tool before parting one of and then repeating for all four.






Most columns of this style also have a half round section between the square base and tapered column so some thick "washers" were parted off and then screwed onto a mandrel for profiling.



It was now just a case of assembling the various parts with soem Araldite expoy adhesive and setting aside for 24hrs to cure. After the top spigot was held in teh 3-jaw with the capitol hard up against the jaws which acted as a stop. It was then just a case of locking teh carriage and facing each end to final size which ensured all would be the same length.



Close up of the bottom



And progress so far at which point I started to think that it could possible take a larger diameter flywheel :thinking:







Offline Bearcar1

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Re: Reinventing the Real.
« Reply #21 on: June 02, 2022, 07:40:03 PM »
 :popcorn: :wine1:  I've been quietly following along on your journey Jason, and I have thoroughly enjoyed the ride!  Larger flywheel? Well, maybe. The embellishments you have done so far make this an interesting piece of machinery.


BC1
Jim

Offline Jasonb

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Re: Reinventing the Real.
« Reply #22 on: June 04, 2022, 04:54:18 PM »
Don't worry Jim, the flywheel grew on me and as you will see if you continue to follow along it looks OK on the finished engine.

Stuarts use a square cylinder end cover to mount it to the base but as mine has the rounded projection that really needs a round cover to match. So a slice was sawn of some 60mm CI bar, faced and the OD turned. I then flipped it round in the soft jaws to face down to finished thickness and turn the locating spigot for the cylinder



Once again I used the mating part to gauge the fit of the spigot into the cylinder



The only remaining turning was to bore a shallow recess to give some clearance for the piston lock nut.



Then over to the mill, the clamps are set at approx 45deg so I can use an edge finder to locate X and Y then the drilling can commence, The six 2.5mm holes were later csk on the underside for socket head CSK screws. The five 4mm holes are for studs to hold the cover to the base. They are not equally spaced, the ones at 4 and 8 o'clock are a little more forward as I was toying with the idea of adding drain cock bosses to the side of the cylinder but decided not to in the end as I don't really need them with air but the thought is there if anyone wants to try these modifications and run on steam. I went with 4mm as the Stuart specified 2BA (4.7mm)looks a bit bulky particularly with their full size hex heads, my nuts will be 5.5mm A/F



Two slices from the same 60mm cast iron bar can be cut and machined to the overall sizes of the valve chest and it's cover. Then a spigot turned on the end of the valve chest with a round nosed tool before drilling and reaming for the valve rod. I'm not keen on having to drill a guide hole for the rod at the opposite end of the valve chest so once again deviated from the Stuart design and I will use a separate external guide similar to that found on their No1. I opted for round glands to keep the round theme going but oval ones are not too hard to do on the rotary table of you prefer.



The middle was then stitch drilled out before cleaning up with a 3mm milling cutter then the revised eight hole pattern for the studs drilled, this pattern will allow me to bring the steam/air in through the side of the chest without clashing with a central stud and does away with Stuarts method of attaching the steam supply to the valve chest cover which can be a pain when you want to adjust the valve as you have to strip out the pipework each time.



The chest cover was drilled straight after and then a decorative recess milled with a 4mm dia x 1mm corner radius cutter





« Last Edit: June 04, 2022, 04:57:30 PM by Jasonb »

Offline Jasonb

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Re: Reinventing the Real.
« Reply #23 on: June 09, 2022, 08:16:49 PM »
As i doubt my engine will ever do enough hours to need the bearings adjusting I did not bother to make them split, instead I just turned them from bar. The inside was bored to get the fit I wanted on the crankshaft and the waist in the middle to fit the bearing supports before being parted off.



The M5 acorn nuts were made from round bar milled to one size smaller hex (7mm) and then the ball turner was used to shape them, the triangular insert has the advantage of leaving a nice chamfer on the top of the hex. After parting off they were held in a hex collet though a 3-jaw would do and drilled and tapped M5. While the ball turner was set up I also made two M3 versions to go on the top of the crosshead guide rods





Here are the bearings and nuts in place



You may also notice in the above photo a slice of ERW tube which is the basis for the more attractive pulley rather than the standard cast Stuart item that they use on all the 2 x 1 engines. The spokes were cut from a piece of 2.5mm steel sheet which was quite easy on the CNC but all the curves are parts of circles so could be done on a rotary table.





After a bit of "softening" with the dremel and turning two bits of steel that will form the hub all were ready for soldering.





held in the 3-jaw the outer face was cleaned up followed by the edge of the rim & hub and finally the undersize hole in the hub was bored out to fit the crankshaft



I then swapped to external jaws so that the other side could be finished



That's another part that can be crossed off the list.




Offline crueby

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Re: Reinventing the Real.
« Reply #24 on: June 09, 2022, 08:21:52 PM »
Love the acorn nuts and the curved spokes on the wheel!  Which ball turner setup do you have?

Offline Jasonb

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Re: Reinventing the Real.
« Reply #25 on: June 09, 2022, 08:39:47 PM »
Thanks, I made a Bedair type one some time ago.


Offline crueby

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Re: Reinventing the Real.
« Reply #26 on: June 09, 2022, 08:45:52 PM »
 :headscratch: How does that turn the outside of the acorn nut ends....

Offline Admiral_dk

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Re: Reinventing the Real.
« Reply #27 on: June 09, 2022, 10:04:04 PM »
Quote
:headscratch: How does that turn the outside of the acorn nut ends....

Move the Cutter to the Outside instead of the Inside off the Centre off the Tool - see the "Moving Sledge" in the middle ....

I really like your additional details Jason  :ThumbsUp:

Per

Offline Jasonb

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Re: Reinventing the Real.
« Reply #28 on: June 10, 2022, 06:59:50 AM »
In the photo of the ball turner I have it set for concave cutting eg the insert is beyond the axis of rotation. For balls and convex surfaces I slide it back behind the axis and the cutter follows an arc. If that's not clear say so and I'll video it in action.

The final shape be it a ball or acorn is just a case of positioning the axis and the radius of the cut

Offline crueby

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Re: Reinventing the Real.
« Reply #29 on: June 10, 2022, 01:13:24 PM »
Got it, at first I didn't realize that the block was lower than the lathe acis and the cutter projects up.


 :ThumbsUp: