Author Topic: Marcher, a twin cylinder marine steam engine  (Read 4089 times)

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #45 on: September 17, 2018, 06:44:42 AM »
Thank you very much George for your kind words. I always try to make my parts as accurately as possible according to dimensions and also visually appealing. Sometimes it works, sometimes it doesn't. One thing that got me building the Marcher is the outlook of the cast parts, which gives the engine the look of a real old steam engine; rather than only fabricate everything from stock materials.

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #46 on: September 23, 2018, 12:07:37 PM »
Cylinder covers underneath cylinder block were made next. Normal turning work at the lathe. Internal threads for piston rod glands were made with M6x0,75 tap. After that the glands for piston rods were turned of 10 mm brass rod. M6x0,75 threads were made with a die holder held at tailstock chuck. Threads were made by rotating manually the lathe spindle.
After that the workpiece was moved into a collet held in rotary table, and 6 pcs 1,6 mm horizontal holes drilled into piston rod glands.
« Last Edit: September 23, 2018, 12:13:00 PM by Moxis »

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #47 on: September 27, 2018, 08:27:25 AM »
Making the trunk guides was the next task. Casting including both guides is provided for these.  Again a little while was necessary to think in which order the parts must be turned, because on the other end of the guide there is only a narrow flange without possibility to grip it into the lathe chuck.

So the only possibility was to turn both ends of the casting into final measurements and only then part them off of each other. Then face the narrow flange into final thickness, bore the hole, and voila, we are almost there.

The only thing that remained was to take the parts into milling machine and mill the slots on both sides of the guide, drill the holes for fastening screws (M2), and the parts were ready for installing.
« Last Edit: September 27, 2018, 08:33:15 AM by Moxis »

Online Ye-Ole Steam Dude

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Re: Marcher, a twin cylinder marine steam engine
« Reply #48 on: September 27, 2018, 08:32:15 AM »
Hello Moxis,

Coming along real well.

Have a great day,
Thomas

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #49 on: October 03, 2018, 03:18:28 PM »
Thank you Thomas for your kind words and interest to my build. It is always nice to get comments from you guys, it increases a lot motivation to work forward.

This time I will show a small update, how I was making the connecting rods. This was rather complicated task with some quite accurate machining to get everything straight and running freely.

There was one gunmetal casting provided for both big end bearings. This was first faced and milled into final dimensions. Holes for halves of bearing screws (M2) were drilled, the upper part sawn away with 1 mm thick slitting saw, and threads made to the lower part. I make always internal threads so that after drilling the hole, I attach the tap into drilling chuck, and without moving the table, start the thread my rotating manually the chuck. After a couple of revolutions I withdraw the chuck and install the winding iron (not sure about name of this tool) and complete the thread manually. This ensures that the thread is absolutely straight.

After making the threads, the two halves of the bearing were attached into lathe 4 jaw chuck, and hole for camshaft was drilled & reamed. Connecting rod itself was turned of mild steel and attached into bearing block with M2 screw & epoxy glue. The unit was then turned into shape, upper end drilled and brass bush inserted there. Finally the flats for upper end were milled and the whole unit cleaned with 400 grit emery paper.
« Last Edit: October 03, 2018, 03:22:13 PM by Moxis »

Offline Admiral_dk

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Re: Marcher, a twin cylinder marine steam engine
« Reply #50 on: October 03, 2018, 10:18:34 PM »
It really starts to look like a engine that could run (I can see what is missing) - nice finish  :ThumbsUp:

 :popcorn:

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #51 on: October 10, 2018, 03:11:42 PM »
Thanks Admiral_dk, I really hope that you are right. The worst thing that could happen is, when you try to start the engine it doesn`t run and you notice that you have done something fundamentally wrong.

Well let`s not think that yet. This time I made the piston, piston rod and crosshead. No casting was provided for these, so they had to be made of stock material. I had a piece of 12 mm brass rod available, so the parts were turned very fast. The only thing which I made differently from plan was the connecting pin for the cross head. Instead of a slot screw, I wanted it to be operated with allen key, so it was made of 3 mm silver steel which was first bored with 1,7 mm, M2 thread cut into it, and finally a M2 grub screw attached at the other end, and a M2 normal screw to the other. These were fixed then with epoxy.

Installing these parts together was quite accurate work, parts had to be sanded carefully here and there to get them moving freely. Finally that succeeded, and next task can be started.


Offline K.B.C

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Re: Marcher, a twin cylinder marine steam engine
« Reply #52 on: October 10, 2018, 09:10:12 PM »
Hi Moxis,

It's a good idea in one way to fit Cross Head pins with Hex for M2 grub screws but not so good in another way.

If you have the M2 grubs it will be difficult if you have to undo them after the reverse gear has been fitted and the engine timed, as the key will not be long enough to get thro' all of the levers.
If they are slotted a small screw driver can get thro' with ought dismantling the gear which is a bit of a pain as the engine will need to be timed again, otherwise you are making an excellent little engine.

I mentioned some time ago that you should bore the end of the shaft at the flywheel end 3'16" x 7/16" deep to fit a 3/16" dia shaft to take a coupling, as I have done on my Marcher.

Hope this helps.

George.
Your never too old to learn.

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #53 on: October 11, 2018, 07:25:24 AM »
Good point George, that I didn't think when making those pins. I have to consider this again.
Could you show a picture about your coupling at the flywheel end, I didn't quite understand the idea.

Offline K.B.C

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Re: Marcher, a twin cylinder marine steam engine
« Reply #54 on: October 11, 2018, 12:28:47 PM »
Good point George, that I didn't think when making those pins. I have to consider this again.
Could you show a picture about your coupling at the flywheel end, I didn't quite understand the idea.

Moxis.

Pic of the shaft end shows the 3/16" dia x 7/16" deep bored hole, this allows you to fit in a piece of 3/16" dia rod ( glue in with Loctite 603 , the green stuff) and then a universal coupling can be fitted.
If not you need to fit drive pins at 180 deg on the end of the flywheel to pic up holes in a disc fitted to the prop shaft.
I make all of my own couplings with the old fashioned ball and pin screwed to take a prop shaft with a lock nut on it.

Video of Marcher engine on air at 10 p.s.i. 
note that the engine runs well without flywheel.

George.
Your never too old to learn.

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #55 on: October 11, 2018, 12:51:27 PM »
Thanks for the video and photos George, now I understand the idea. I have to follow that and build the ball/pin coupling you suggested.

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #56 on: October 11, 2018, 04:18:30 PM »
Small update: Today I finally dared to start making the steam ports. After careful marking 1,2 mm holes were drilled first at each end of the narrow inlet ports and 2,4 mm at the outlet port. There was no dimension for the depth of the ports in the drawing, but roughly calculated the narrow ports were 3,5 mm and the outlet port 7,5 mm deep.
Inlet ports were then milled very carefully using a dia 1 mm cutter, taking only 0,5 mm at each run. A 2 mm cutter was used for the outlet ports.

And for my great surprise everything went well and now I have quite useful steam ports on my cylinder block (I hope).

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #57 on: October 13, 2018, 01:17:00 PM »
Very careful drilling was necessary to make the steam passages  to cylinders. Angle and depth had to be exactly right for not to drill into wrong port. Drawing didn`t give any diameter for the drill, but 2,2 mm seemed to be about right.

Offline Moxis

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Re: Marcher, a twin cylinder marine steam engine
« Reply #58 on: November 01, 2018, 09:22:09 AM »
Thank you all who have followed my blog and have interest towards it. There has been quite a long time after the last update. This is due to other engagements and also some faults I made during machining of slide valve chest castings, but now everything is solved and I can continue.

So the next item was to fabricate the slide valve chests, covers & slide valves with all very tiny parts involved. Slide valve chests are supplied as a paired casting. This was first milled at final thickness. The two valve chests were then separated from each other using slitting saw, and outer sides milled into final dimensions. Holes for valve rods were drilled  and the upper holes tapped M5x0,5. Oval flanges for valve rod glands were milled using rotary table.
Covers for valve chests were turned in 4jaw chuck and holes for M2 studs drilled. Valve rods were turned of 2,5 mm stainless steel and M2 threads cut at the lower ends.

The valves themselves were machined of  pieces of brass, but insted of cutting threads to the valve rods for their adjustment, I used method suggested by some of you by using M2 grub screws to lock the slides to the rods. I am sure this makes final timing much easier than to use the method suggested at the drawing.

A lot of milling work was involved into these items, and I am glad this is done and I can concentrate myself into next items.
« Last Edit: November 01, 2018, 09:32:04 AM by Moxis »

Online Ye-Ole Steam Dude

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Re: Marcher, a twin cylinder marine steam engine
« Reply #59 on: November 01, 2018, 09:27:52 AM »
Hello Moxis,

Your project is looking real good.

Have a great day,
Thomas