Author Topic: Wright Brothers 1903 Engine  (Read 45338 times)

Offline b.lindsey

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Re: Wright Brothers 1903 Engine
« Reply #15 on: January 14, 2013, 12:11:54 PM »
As noted in a previous post, the smallish (for me at least) combustion chambers I see as the make or break part of the project. If these can be done successfully, the the project will continue. The current plan is to make one complete combustion chamber including the valves, valve cages and igniter parts and the to access the viability of that in 1/4 scale. Phase one of the plan was to make the combustion chamber housing. The original part was cast iron, likely from a casting, and I wanted to try and replicate this in the same material. This is shown in the pictures below.  Just this much (and its not finished yet) required two full afternoons of shop time. What remains if to thread both ends 5/8"-40 for the valve cage retainer rings, taper turn the protruding portion to make the spigot that will attach to the end og the cylinder and thread it 1/2"-40, tap the port holes for the igniter terminals and enlarge the bore in the center part of the chamber where the combustion will take place.

As shown in the pictures, all of the operations were done in the four jaw chuck, and only after this was all done was the part removed, turned around and the opposite end turned down to the required diameter. Fortunately the 4 jaw chuck can be removed from the lathe and attached to the vertically oriented roatary table on the mill which kept everything concentric.

The pictures below show:

1) The raw CI stock chucked on the lathe and centered on a previously drilled 1/2" bore for one end to be turned to the finished diamemter.
2)The various counterbores for the valve cage, retainer ring, etc. (Chuck removed to show this better).
3)Turning the center portion to remove as much stock a possible.
4) The part and chuck mounted in the RT vertically to square up the four sides and to round the back side opposite the spigot (thought this is not shown).
5) Milling the six port holes for the exhaust to exit on the bottom end of the chamber.
6) Drilling the holes for the two igniter terminals which remain to be tapped.




Offline b.lindsey

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Re: Wright Brothers 1903 Engine
« Reply #16 on: January 14, 2013, 12:21:17 PM »
After this was done some filing and finishing on fine grit paper cleaned things up and polished the machined surfaces better than I had expected. So far, so good, though I am still concerned as to the threading of the ends and spigot since the length of these threads is quite shallow (.078") for the valve cage retainers and slightly more than that for the spigot which will attach the whole thing to the cylinder end. Several lessons were learned in the process which will hopefully cut some machining time from the remaining three housings, but again, I want to finish one complete combustion chamber in 1/4 scale includin the valves, cages, springs, and igniter parts to see if this can be done in this scale (or rather if I can do it) with a reasonable chance of success. So stay tuned.

The few pictures below show the semi-finished housing as it stands now.


Offline b.lindsey

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Re: Wright Brothers 1903 Engine
« Reply #17 on: January 14, 2013, 12:28:04 PM »
The attached .pdf file of the housing may make some of the above clearer I hope.


Offline gbritnell

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Re: Wright Brothers 1903 Engine
« Reply #18 on: January 14, 2013, 01:13:04 PM »
Hi Bill,
Great work so far.  Long before there were dedicated engineering shows the only place a fellow could display his handiwork was at the local farm and antique engine shows. Living in northern Ohio and not far from Norwalk I met Lloyd 'Jim' Butler. He like the rest of us had a collection of hit and miss engines and he would pick up unique engines along the way. He had his flying license but had quit by the time I met him due to health problems, which only got worse. I remember when he started the Wright engine and saw it finished at NAMES one year but I never saw it run. I lost track of him as he quit going to the shows and then one of our fellow modelers from the area said that he had passed.
As far as threading your cylinders why not try the approach that I did when I made the radial engine. Make a manual crank handle for whatever lathe you are using and turn it by hand. That way you can sneak up against a shoulder without worrying about over-cutting. It takes a little longer but works out great. That is unless you have a lathe that will kick out at the same spot every time.
gbritnell
Talent unshared is talent wasted.

Offline b.lindsey

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Re: Wright Brothers 1903 Engine
« Reply #19 on: January 14, 2013, 01:39:04 PM »
George, thank for that information about Mr. Butler. I am hoping that at some point he got his engine to run if only to prove that it can be done in 1/4 scale. Even if not though, his model as shown in that link I posted at the outset is a real beauty.

As to the threading I think you are right and since most of this smaller work will be done on the Sherline lathe I am planning to order the threading attachment which does in fact have a hand wheel as you describe and comes with the various change gears needed to cut up to 80 tpi as i recall.  The thread lengths are so shallow in most places that even a bottoming  tap would not be sufficient and given some of the odd sizes (and the fact that other components have both RH and LH threads) the Sherline attachment is by far more cost effective and can be used for other things later on as well. Now I will just need to grind (as best as I can figure out now) a threading bit from 1/16" square stock, flattened on one side so as to get right up to the shoulder as you say...and a holder for said bit.

As our resident "master of miniature" things, I may be picking your brain some more in the days to come as well.

BIll

Offline vcutajar

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Re: Wright Brothers 1903 Engine
« Reply #20 on: January 14, 2013, 02:54:31 PM »
Bill, are you making the drawings yourself?  Lookong forward to your next build installment.

Vince

Offline 90LX_Notch

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Re: Wright Brothers 1903 Engine
« Reply #21 on: January 14, 2013, 02:57:34 PM »
Bill-

What I've found to be the hardest part of making really small stuff is holding it.  That's the biggest challenge.  Machining it isn't bad.  Establish a datum and come off of it with the dials.  If you try to do it with your eyes and scribe lines it becomes very difficult.  For lathe parts I use a carriage stop that I stop the carriage feed just short of and finish up to by hand.  I also set the compound parallel to the ways and use it's dial to adjust the length of the cut relative to the stop.  For example, if you reach the stop and the part measures .005 short from the face to a shoulder, dial the compound .005 and the length will be correct.

It's analogous to flying at night by instruments.  The dials are your friends.  (Better friends are DROs!)

You have much better skills then I; you'll have no problems machinig the small parts.

-Bob
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Offline b.lindsey

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Re: Wright Brothers 1903 Engine
« Reply #22 on: January 14, 2013, 04:05:13 PM »
Thanks Vince and Bob. I rarely sribe lines (read virtually never!) but rather measure and then use the dials which even on the Sherline equipment I have found to be very reliable. DRO's are great and I have those on the large machines at work but am not crazy about Sherlines DRO system and much prefer glass or similar scales to their optical wheel system especially for the price.

Vince...I am making the 1/4 scale drawings myself from the full sized plans commissioned by the National Air & Space Museum which I noted at the outset. The problem is that not everything will scale down perfectly (such as some of the thread sizes) so some liscense and/or judgement has to be made at times. I find that if I work from my own drawings, many if not most of the errors or omissions will show up so I can correct them as I go along.  I did the same thing with the Briggs build.

Bill

Offline Tennessee Whiskey

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Re: Wright Brothers 1903 Engine
« Reply #23 on: January 14, 2013, 05:20:19 PM »
Bill, when you first mentioned threading I was thinking about a die and shallow shoulder,but, I re-read and it's the internal thread.  Could you take your 1/16 square stock and cut the correct thread profile,face square, harden a little and "tap" or maybe just cut a bottom tap at near full thrd. dia. I'm new at this and just trying to figure what won't work.
Eric

Offline gbritnell

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Re: Wright Brothers 1903 Engine
« Reply #24 on: January 14, 2013, 05:56:30 PM »
Bill,
If I may answer Eric's question? The problem with tapping shallow holes is twofold. The first thing is trying to get enough thread started to follow up with a bottom or ground off tap. The second thing is even if you get enough of a start when you put in the bottom or ground off tap and start turning it you virtually have no 'feel' of how it's cutting and more times than not you will actually cut out the existing threads by over torquing the tap. For shallow threads I always use my hand crank. That way you can go right up against a shoulder and you can feel when to stop.
gbritnell
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Offline b.lindsey

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Re: Wright Brothers 1903 Engine
« Reply #25 on: January 14, 2013, 05:57:38 PM »
Eric, the best solution will be to single point the threads both internal and external. I am coming up with so many odd non-standard sizes like 1/2"-40, 5/8"-40 etc. that to modify existing taps would be painfully expensive. The attachment  for the Sherline will handle both LH and RH threads. The reason for the 1/16" size of the threading bit is simply to get into the smaller spaces.  At 40 tpi, the threads don't have to be that deep, and as George noted, doing it by a hand crank on the spindle will allow more control and the ability to sneak up right to the shoulder without going beyond. Sounds good in theory at least. I will post pictures if it works out as I hope.

Bill

Offline b.lindsey

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Re: Wright Brothers 1903 Engine
« Reply #26 on: January 14, 2013, 06:00:36 PM »
Sorry George, I was typing at the same time, but your points are very valid too. I still use taps and dies when I have them and the job allows for them, but you have convinced me of the merits of the hand crank for these particular applications and that fortunately plays right into the design of the available Sherline attachment.

Bill

EDIT:  Keep in mind that even at 40 tpi, the length of most of these internal threads will only allow for 3-4 threads...maybe 5 if i'm lucky in places. Not a lot of holding power which worries me somewhat.

Offline 90LX_Notch

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Re: Wright Brothers 1903 Engine
« Reply #27 on: January 14, 2013, 07:55:42 PM »
Bill-

This something to consider for the internal threading- a circular form tool.  I stumbled across some punches for die sets at a yard sale once and bought them.  Years later I needed to cut a 5/16-32 internal thread.  I didn't have the tap and the project needed to get done that day.  After brainstorming, I decided to chuck one up of the punches and try a carbide tool on it.  Much to my surprise the carbide cut it.  I set the compound for one side and then the other and machined a 60 degree form.  I then ground it to 1/2 the dia. of the form and honed it.  The only other thing  I did was to make a split bushing so my 3/8 dia boring bar holder could hold the .147 dia shank. 

The tool very worked well.  However, I've only used it that day on aluminum.

I would think that a similar tool out of tool steel would work if properly hardend and tempered.

For size- The dia. of the form is .230 and the shank is .147.  The .147 is what the punch was ground to when I bought it.  If I needed to get in tight like you, I would grind or machine the face back.

-Bob
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Offline steamer

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Re: Wright Brothers 1903 Engine
« Reply #28 on: January 14, 2013, 08:11:08 PM »
YES!

That works very well for single pointing....SB has one to make in their project book.

Dave
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Offline b.lindsey

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Re: Wright Brothers 1903 Engine
« Reply #29 on: January 14, 2013, 08:22:30 PM »
That could certainly work and since the holes needing threading are not that small the shank could even be more robust (say .250" or even .375") almost all the way up to the cutting edge for more rigidity.

Bill