Author Topic: 1/3rd Scale Allman Vertical Engine  (Read 15781 times)

Offline Jasonb

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1/3rd Scale Allman Vertical Engine
« on: May 03, 2016, 07:42:03 PM »


This is a kit based on the 3/4HP Vertical engine by Allman Gas Engine Co. of New York in 1/3rd scale. The kit was available for a short run from Debolt back in about 1990 and my kit had passed through a few hand before finding it's way to me.

There are not that many castings to the kit but it does include a few lumps of bar stock and a good set of hardware including fixings, springs, gears, valves etc





As you may be able to guess from the cardboard box my set came across the sea from the Emerald Isle ;)





The previous owner had made a tentative start by turning the bottom of the base flat and cleaning up the lower part of the main frame casting which is the grey primes area in the photo above, he supplied these couple of photos .







Having studied the main base casting for a while and used the height gauge to see where the various cuts would end up I came up with a plan of attack.

First was to machine the two bearing cap mating surfaces and tidy up the sides, I also added the stud holes and tapped for the oilers. Having the caps machined to this stage would save me having to disturb the main casting once I started working on it.



I spent a while squaring things up on the mill and deciding where best the centre line was and then machined the other mating face for the bearings to height and tapped for fixings.





Then using a 3 tooth 40mm dia indexable milling cutter I cleaned up all the outer edges.



The gap between bearings was too big for the 40mm cutter so I changed to a "little hogger" which is 1" dia to clean up the inner faces. You may notice that the bearing blocks are now narrower than the "cast" columns below when infact they should be narrower, one of the downsides of using castings. Still only a minor issue and nothing that cant be dealt with as you will see later.



While set up in this position I drilled the 4 mounting holes in the base, this required making an extended pilot drill and then opening up with an extra long 6.5mm drill which is a good clearance size for the 1/4" fixings.



There is also a tapped hole required for the rocker arm pivot which was drilled with the above two sizes followed by a 9mm extra long bit.



I was just able to get the quill down far enough to guide the top of the tap while it was turned with an open ended spanner.



More work on the base to follow.

J
« Last Edit: May 03, 2016, 08:38:49 PM by Jasonb »

Online Jo

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #1 on: May 03, 2016, 07:57:41 PM »
Jason's got another set of castings  :o This can't be right  :stickpoke: I thought you said something about you don't need castings, you prefer to make engines out of bar stock.

I like the new lathe  8)

Jo

P.S. I can free of charge send a courier to relieve you of any other casting sets that are hindering your progress with your bar stock engines   ;)
Enjoyment is more important than achievement.

Offline Tennessee Whiskey

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #2 on: May 03, 2016, 08:08:18 PM »
Jason,  WTF, you've seen sneaked one in on us and stirred the "Queen of Machine" in the process  :lolb:. Is this one finished?  :lolb:

Cletus

Offline b.lindsey

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #3 on: May 03, 2016, 08:10:16 PM »
Finished or not, nice looking set of castings and a nice looking engine too!! They are obviously well aged :)

Bill

Offline NickG

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #4 on: May 03, 2016, 08:11:21 PM »
I like these old vertical engines, something a bit different to look at when they're running.

Sent from my LG-H340n using Tapatalk


Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #5 on: May 03, 2016, 08:20:16 PM »
Cletus, you should know me by now, unlike queenie this one is not only finished but also running ;) I want to tweak it a bit more before I slap some paint on it but that should be done by the time I get to the end of the build thread.

Jo I thought I better get this one out the way then that only leaves me a couple of those nasty casting sets left getting in the way, although the two I have left will require a lot of scratch built work for what I have in mind for them, one being something I have never seen modeled before. I do find this so much more rewarding than just knocking out the same old models that have been built time and time again.

As you should have guessed from my response to that list of castings you e-mailed yesterday there is not a lot that interests me particularly if they are overpriced or have faulty castings, my currently being worked on engine being a perfect example of this. ;D

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #6 on: May 03, 2016, 08:28:27 PM »
Bill, you noticed that brown aged patina then :-[

Nick, that was one of the things that tempted me to this kit, its quite an old design and has sufficient different parts and construction to keep me interested unlike a lot of the horizontal push rod hit & miss engines which are just different versions of a similar thing. I may even be tempted to try and convert it to hot tube ignition like the original had once it is running completely to my liking.

Offline Dave Otto

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #7 on: May 03, 2016, 09:39:42 PM »
Hi Jason

Good to see you posting another one of your fine builds! I picked up one of these engines second hand a number of years ago as a Mechanics kit (all parts machined by Debolt); and thought that it would be fun to try to make it more like the engraving in your intro post. I will most likely never get to it and will probably just let it go.

It will be fun to sit back and watch how you finish yours.

Dave

Offline zeeprogrammer

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #8 on: May 03, 2016, 09:56:45 PM »
 :popcorn:

Should be fun.

Kinda too bad you've already seen the end of the movie.  :ROFL:
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Offline b.lindsey

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #9 on: May 03, 2016, 11:28:33 PM »
:popcorn:


Kinda too bad you've already seen the end of the movie.  :ROFL:

Yeah I hate when that happens. But it does reduce the chance of banter and the odd recipe taking things off track :)

Bill

Online Jo

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #10 on: May 04, 2016, 11:08:22 AM »
As you should have guessed from my response to that list of castings you e-mailed yesterday there is not a lot that interests me particularly if they are overpriced or have faulty castings, my currently being worked on engine being a perfect example of this.  ;D

The Corliss cross compound wins the prize of being my most expensive set of casting I have ever paid for at £300 inc P&P (actually they were hand delivered By Peter Southworth  8)). I wouldn't mention you paid more than that for this set of castings :hellno:

:popcorn:


Kinda too bad you've already seen the end of the movie.  :ROFL:

Yeah I hate when that happens. But it does reduce the chance of banter and the odd recipe taking things off track :)

Bill

And the chance of Jason having to admit to doing something wrong  :lolb:

Jo

Enjoyment is more important than achievement.

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #11 on: May 04, 2016, 01:12:06 PM »
Dave, I'm probably going to leave this one more or less as per the Debolt drawings, there is another version of this engine by Alyn Foundry which is a hot tube ignition one so that would be more suited to getting the correct shape of the linkages etc. This would not be hard to make from scratch if I go down that route. I will hopefully at some time have castings for the other Allman engine which has twin A frames rather than the tuning fork so that is another option.

Zee I'm affraid there won't be much mention of food in this thread, having got it from a pile of castings to a running engine in 8 weeks of evenings and part weekends there was not much time for things like eating :LittleDevil:

Jo I suppose it comes down to rarity and desirability, anyone can go out and buy a set of new Southworth castings today. These engines were only done in small runs and that was 30 odd years ago so there are not so many virgin sets about. You also need to allow for the fact that a lot of the good stuff has to come from far away and previous owners like to recoupe the substantial postage costs and any duty paid. Mine was also hand delivered by a very nice man. You have also been spoilt a bit by having a tame supplier who can be beaten down on price especially when he has over indulged his machine addiction, the rest of us tend to have to pay the going rate.

Luckily I don't seem to make as many errors as some so that is why you won't see many in my threads but they will be there when and if they happen.

Online Jo

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #12 on: May 04, 2016, 01:38:48 PM »
Jo I suppose it comes down to rarity and desirability, anyone can go out and buy a set of new Southworth castings today. These engines were only done in small runs and that was 30 odd years ago so there are not so many virgin sets about. ...... You have also been spoilt a bit by having a tame supplier who can be beaten down on price especially when he has over indulged his machine addiction, the rest of us tend to have to pay the going rate.

The Corliss Cross Compound is very rare and  :Love: extremely desirable but more than a bit daunting for most model makers. The castings are done to order as the set works out at about 58Kgs and as Peter said to me they take up a lot of space so he did not keep them on the shelf (it would have needed to be a very strong shelf). How many finished Cross Compounds or for that matter Double Tandem Compounds have you seen? Or even Videos of them running  :headscratch:

There are people out there who will pay foolish money for a 'rare' set of castings  :Doh: I pay up to and not beyond the standard second hand casting set price of 50% of the manufacturers original cost and however desperate my supplier gets he never undercuts his original cost   :disappointed:.

Jo

P.S.  That makes  :o three sets of castings I think I should send up a courier to relieve you of one of my casting set's big brother  :agree:
Enjoyment is more important than achievement.

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #13 on: May 10, 2016, 06:36:38 PM »
Right, back to the build :)

I now had a flat base and 4 square faces on the bearing blocks so could easily locate the casting for the next operations. Two angle plates were clocked in across the mill bed and the DRO zero'd on them so all hights could be set out from the base. I used two of the mounting holes and an additional two G-cramps to hold the base to the angle plates.



With some support under the frame and a jack between the forks the first job was to machine the cylinder mounting face flat and to width followed by adding the six holes for the mounting bolts.



At the same seting I then moved up the casting and drilled then bored the two bearing holes which should ensure they are at right angles to the cylinder. To keep things nice and rigid I made up this 20mm dia bar which was about as big as I could  put down the 7/8" hole, fitted nicely into a 20mm ER32 collet.



The casting was then turned 180deg and the various holes for the timing gear, governor and cam follower done. I also machined back the surface of the casting to the required setbacks from the bearing edge.



Turn the casting again and pop in the two 8BA holes for the lubricator bracket and spot face the area around them



Thats about all the work to the main casting, just some clean up that will be done later



For a break from the castings I next made up a few of the steel components that fit the main base, firstly the rocker arm pivot, quite straightforward turning and threading and a HSS tool to do the large concave part.



The live electrical contact consists of a ring that is held to the crankshaft by a grub screw, after turning, boring and parting off it was held in the soft jaws to face to thickness.



Then a flat machined and hole tapped to take the contact stud.



And here are the two completed parts along with the governor latch adjusting screw and rocker arm link



Finally for this installment a few more steel turnings - Crank pin, Latch pivot, Cam follower pivot, conrod small end locknut and latch spring pin.



J
« Last Edit: May 10, 2016, 06:39:42 PM by Jasonb »

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #14 on: May 17, 2016, 07:36:21 PM »
The most obvious thing to machine first on the cylinder casting was the large flat area where it attaches to the main column. A few packers underneath allowed it to be clamped down level to the bed and a similar arrangement with an angle plate behind made sure it would not roll. A 40mm indexable tipped cutter flattened the area and then six mounting holes were drilled and then tapped 1/4" BSF.



If you look closely at the two holes on the right you will see the rear one is far closer to the edge than the one in the foreground, this was due to the two halves of the casting being almost 3/32" out of line >:( This will be attended to at the final fettling.



While set up like this I machined the two sides of the mounting pad straight. Once transfered onto the lathe carrage this edge was clocked true while the casting was packed upto ctr height. Luckily my largest between centres boring bar just fitted the cored hole so that was used to bore the cylinder.



With that done a flycutter was used to machine the head end back to finished length.



Moving back to the mill and using the same angle plate the 4 head stud holes were drilled and tapped 2BA and then it was out with the extra long series drill again to put in the water passage, you may just be able to see the black mark on the drill that shows where it had to penitrate to, all with only 1/8" between the hole and main bore, luckily it did not wander though I almost drilled it in the wrong place but luckily double checked after spot drilling the hole.



The Allman has a similar arrangement to the Gade where there are two exhaust ports, one being the usual valve controlled one at the top end of the stroke and another in the sidewall of the cylinder at the bottom of the stroke. The mounting face for the header was first machined flat and the stud holes tapped. Then a slot milled and finally 4 holes drilled through into the bore.



The spark plug hole and top water outlet are quite straightforward, just milled flat, drilled & tapped.  You can also see that the lower water inlet has been done in the lower left.



The inlet and outlet valves are on opposite sides of the cylinder. The inlet will be covered later but the exhaust is a bit awkward as it is accessed through the inlet opening which required the valve seat to be cut with a long CSk rather than machined as I prefer.



You may be able to see the blue areas where the valve was touching the seat and the clear where it was not :-[ This was slight chatter From the CSK so some lapping was required.



The final job was to drill a passage up through the cavity behind the exhaust valve to join two of the four holes that lead to the header. This was then tapped for a plug as was the long water passage hole.



The cylinder head is a simple turning job from a bit of CI bar. it then needs clearance for the two valved and spark plug cut which I did by plunging with milling cutters.



Finished cylinder and head.


J

Offline zeeprogrammer

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #15 on: May 17, 2016, 10:01:56 PM »
Just catching up. Always an enjoyable read and loads of learning.

Bummer about the lack of food.  ;D
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Offline b.lindsey

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #16 on: May 18, 2016, 12:51:53 AM »
Great pictures Jason and some very nice progress too. Its going to be a beauty....well I guess it already is, but looking forward to the end of the movie :)

Bill

Offline Dave Otto

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #17 on: May 18, 2016, 02:06:05 AM »
Looking good Jason!

Dave

Offline Art K

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #18 on: May 18, 2016, 03:00:31 AM »
Jason,
I just caught your build looks like a good catch with the castings and promises to be a good build.
Art
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Offline RayW

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #19 on: May 18, 2016, 10:54:38 AM »
Hi Jason,

Looks a really interesting build. Following your progress with interest and looking forward to seeing the finished product in action.

Ray
Ray

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #20 on: May 28, 2016, 08:34:32 PM »
Thanks for the comments chaps.

The Allman differes from a lot of hit and miss engines by having it's governor weights inside the pully rather than the more common position on inside the flywheel.

A piece of hollow CI bar is supplied for the pully. First job was to turn the outside diameter, you should be able to see three different bands on the surface this is where I have made two slightly tapered cuts either side of a centrall parallel section, these bands will get blended to form the crown of the pully later.



Next using a sturdy 16mm diameter boring bar the inside was opened out to the required 2.125" diameter. I placed the hold down stud and nuts on the bed to act as a carrage stop so I did not run the boring bar out the far end and into the chuck jaws.



With that done the pully was reversed in the chuck and taken down to final length leaving a small flange at the end which stops any stray belts wandering into the timing gears.



Finally a clearance hole for a hex key was added.



The governor arm bracket is very similar to a lot of others though quite a bit deeper. First thing to do was machine the outside for a press fit into the pully and then bore 5/8" for the crankshaft.



After facing the rear down to final length it's over to the mill and fix the bracket to a mandrel which could be held in the indexer. Mill the two slots for the governor arms and then rotate 90 degrees to drill & ream for the pivot pins.



The two governor weights were turned from a slice of brass, cut in half and then a flat bottomed hole cut with a 2-flute milling cutter was added to press the arms into.



For the arms a bit of steel was milled upto size and the spigot that presses into the weight turned on either end.



After cutting in half and milling to length the pivot hole was drilled & reamed and a larger hole added to form the inside curve of the arm. Note I have a piece of scrap aluminium to cut into rather than the vice jaw which is always preferable.



A bit more milling and filing and the arms could be pressed into the weights with a bit of loctite for good measure.



Once I had checked that the weights moved freely in their slots and broached a 3/16" keyway the bracket could be pressed into the pully, I used the mills quill to do this.



All that was left was to blend in the crown of the pully with teh assembled parts on a temporary shaft in the lathe.

J

Offline NickG

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #21 on: May 29, 2016, 06:32:31 PM »
Looks great that Jason, thanks for very clear and concise notes on your method.

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #22 on: May 30, 2016, 08:27:39 AM »
Thanks Nick.

I just remembered that I took a short Video of the cylinder being bored and forgot to add that earlier so here it is.

[youtube1]https://www.youtube.com/watch?v=AuWl-SZcC58[/youtube1]

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #23 on: June 07, 2016, 07:52:55 PM »
I decided to go with a built up crankshaft as it was a lot of metal to remove from a 1" x 2" bar. So starting with a piece of 5/8" material it was faced and the hole for the crank pin tapped followed by boring another hole for a spigot on the end of the shaft to fit.



Then with the vice ontop of the rotary table the two ends had the required radius milled onto them.



After silver soldering and cross pining the throw onto a legth of precision ground mild steel the throw was faced back to thickness in the lathe which ensures the face that the pin will tighten down onto is perfectly true to the crankshaft.



Finally a couple of keyways can be milled for the flywheel, timing gear and governor bracket and the pin screwed in and retained with a locknut.



The two bearings were straightforward turning jobs once the two halves had been soldered together, the finished crank was used to judge the final fit.



With the bearings and caps in place they could be drilled for oil holes and then using a long series drill the bottom of the bearing and housing were drilled for a 1/16" pin to stop any risk of the bearings rotating in teh housing.



I was just able to hold the flywheel in the 4-jaw chuck but it was a bit tight getting the jaws to fit between the spokes.



As my left hand tools are quite small section I opted to use a 16mm boring bar mounted upside down and ran teh lathe in reverse to do teh outer face of teh flywheel.

<a href="https://www.youtube.com/watch?v=3YZ0mKAzMgE" target="_blank">http://www.youtube.com/watch?v=3YZ0mKAzMgE</a>#Invalid YouTube Link#

A quick trip to a freindly press owner and the 3/16" keyway was easily broached which allowed the fit to be tested. I think that will do, not too many tight spots :embarassed:

<a href="https://www.youtube.com/watch?v=oTnp2QMo4Dk" target="_blank">http://www.youtube.com/watch?v=oTnp2QMo4Dk</a>

« Last Edit: June 07, 2016, 07:57:55 PM by Jasonb »

Offline zeeprogrammer

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #24 on: June 07, 2016, 11:56:59 PM »
All I did was blink...but I missed some posts here (as elsewhere unfortunately).

What can I say but  :popcorn:

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Offline Dave Otto

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #25 on: June 08, 2016, 12:50:17 AM »
Lots of great progress there Jason!

Dave

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #26 on: June 21, 2016, 07:13:38 PM »
The iron piston casting was first held head end outwards and about 2/3rds of its length cleaned up. I then had a decent surface to hold while the rod end was faced and the skirt opened out with a boring bar.

I then slid the piston forwards so it could be held by the small amount of waste at the top end, the tailstock ctr was brought up for added support and the OD machined to size. After that a DCMT indexable cutter with a 0.4mm tip radius was used to cut the 1/32" wide half round oil grooves.



Once the remaining oil grooves had been done a change to a parting tool soon had the piston ring grooves added too.



Then over to the mill to drill and ream for the wrist pin.



Job done



While I was playing with cast iron a couple of piston rings were made together with some spares.



Being quite an early engine the conrod is more like that found on a steam engine rather than the forged ones found on later hit & miss engines.  Starting with the small end a piece of steel was drilled and tapped and a mandel made to screw it onto. This then gave me enough clearance to use the ball turner to shape the end.



Over to the indexer on the mill and the two opposite faces were milled flat then a cross hole for the wrist pin drilled & reamed 3/8"



The big end is supplied as a bronze casting, the two edges were lightly skimmed so it could be held firmly while the two bolt holes were drilled tapping right through, opened up to clearance part way and then the lower half tapped 2BA. The oiler hole was also tapped at the same time before splitting in half with a slitting saw.



The big end was then bolted together and the rod hole tapped and that end tidied up. Finally it was pushed onto a mandrel to be taken back to width and then with a round nose tool the width reduced further to leave raised central section.



Add a couple of studs and two locnuts so the central rod can't turn and that is the conrod ready to go.





J

Offline Don1966

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #27 on: June 21, 2016, 08:12:30 PM »
Just great work as usual Jason and your one of my heroes........I ...........like........... :praise2:


 :popcorn: Don

Offline Tennessee Whiskey

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #28 on: June 21, 2016, 08:35:00 PM »
Splendid work considering the machines you have  :lolb: :stir:. The DCMT insert has a striking resemblance  to some I just purchased from Warner;  and they do cut nicely.

Cletus

Offline b.lindsey

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #29 on: June 22, 2016, 12:12:33 AM »
Great to see an update on this one Jason. That flywheel sure does turn nice and smooth!!

Bill

Offline Dave Otto

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #30 on: June 22, 2016, 01:11:38 AM »
Nice work as usual Jason!
Good to see continuing progress.

Dave

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #31 on: June 22, 2016, 08:01:16 AM »
Don, I know you are only saying that as I have been showing shiny bronze parts in the last couple of posts, I'm sure you will start to change your mind once the black paint starts to go on :Lol:

Cletus, they are a useful shape to have if working close to the tailstock and also to get down the inside of crank webs. My tool has the pocket on top & bottom so can be used left and right handed. The will also cut 55degree threads.

Bill at the moment it runs longer by hand than by fuel :(

Dave thanks for your continued interest. Thought I had best post some progress as im getting behind the rate of production ;)

Offline Roger B

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #32 on: June 22, 2016, 06:04:48 PM »
The crank runs nicely  :ThumbsUp:  :ThumbsUp: I assume the squeaks in the background are birdsong and not from the engine  :)

Is the groove around the gudgeon pin intended to improve the oil feed?
Best regards

Roger

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #33 on: July 10, 2016, 08:02:41 PM »
Roger, yes I think the groove is there to pick up a little oil and guide it towards the pin. In practice there is a drip feed oiler that puts quite a bit of its content into the upturned piston rather than round the edge.


As can be the case with sets of castings that have passed through the carresing hands of several owners they can leave bits behind. This kit was no exception as the casting for the inlet valve was missing. To remedy this a piece of cast iron bar was turned and then bored & reamed for the valve before transfering to the rotary table to machine the OD which could not be done on the lathe due to a boss for the carb to screw into.



Following some more milling around the boss and a good measure of hand fettling a suitable replacement emerged.



One end of the silencer (muffler) screws into a simple flange that bolts to the block. This was rough turned and then the concave part turned by eye using a rounded tool.



From the other side a central hole was tapped for the cover retaining stud and a series of holes to dissipate the gasses drilled around it.



A short length of brass tube is supplied for the silencer tube, this has an unusual pattern of slots cut into it as an outlet which I did with a couple of slitting saws.



And a group shot of all the exhaust parts





The exhaust valve is opperated by a long vertical rocker arm that runs against an eccentric on the back of the timing gear. The eccentric was turned to leave a small lip on one end before resetting in the 4-jaw to bore the eccentric hole



A CSK hole was added to hold it to the gear and a ring turned to fit over the outside with a couple of oil holes in it.



All assembled onto the gear.



J

Offline Roger B

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #34 on: July 11, 2016, 07:39:48 AM »
That's an interesting silencer design, it looks like it could whistle  :headscratch:
Best regards

Roger

Offline Jasonb

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #35 on: August 22, 2016, 07:31:10 PM »
Whiskey's update on his Redwing made me think that I have not posted about the Allman lately so thought I should write a bit more. I have also got a bit of a backlog with three more completed engines to write up :-[

The carb body is a bronze casting, First job was to hold in the 4-jaw and turn & thread the end that screws into the intake block via an elbow. Once done it was reversed and the other end faced off before drilling the flange for the choke plate. Then cross drilled for needle and fuel inlet. Just one pic of this



The needle was straight forward turning, knurling and threading. I made the angle of the tip a bit shallower to give finer adjustment and also went with a finer thread for the same reason.



This engine has a very large rocker arm to activate the exhaust valve as it has to get the movement from one side of the engine to the other. This again is supplied as a bronze casting. Firstly I clamped it on it's side to face the pivot to thickness and then ream for the pivot post. I then set it up in the vice to face the pad that touches the valve and drilled the hole for the rod from the cam follower. A couple of studs and nuts from my hold down set make rough and ready machinists jacks.



The cam follower is also quite big on the Allman as it transfers the movement of the cam located towards the top of the engine right down to the base. A piece of 1" x 1/4" steel about 7" long was drilled & reamed for the pivot and a shallow slot cut for the governor latch which slides on two small fixing bolts. The hole on the far right takes a link which fits into the rocker arm.



After a bit of shaping this is what it looks like on the engine together with the timing gears and exhaust rocker etc.





This is a close up of the top end where you can see the insulated ignition contact is located. The stud on the collar just behind the small timing gear makes contact with this and completes the ignition circuit. As the contact is on the cam follower the next time the stud comes round the follower is pushed away by the cam so you only get one spark per cycle. Also as the follower is held off by the governor this acts as a spark saver when the engine is on a "miss"



The last bit of tarting up was to make some bearing oil pots and a drip feed oiler for the piston which feeds into the open end of the cylinder via a short length of copper pipe.





I also did not like the way the hold down bolts would have tightened against the slight slope of the base so make a counter bore that could fit on a long rod to cut a recess into which I JB Welded some thick turned washers.



So with all the bits made it was time to try a bit of fuel through it. I have heard that these engines are not the easiest to get running and this one has proved no exception. It will run but not for very long but here is a quick video that I managed to grab before it died out. I have not had a chance to run it any more as I wanted to get it stripped and painted for the Guildford show and will probably wait until the autumn as its a bit hot to keep flicking flywheels round at the moment.

<a href="https://www.youtube.com/watch?v=62_6ssYWs3c" target="_blank">http://www.youtube.com/watch?v=62_6ssYWs3c</a>

J


« Last Edit: August 22, 2016, 07:36:25 PM by Jasonb »

Offline Myrickman

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #36 on: August 22, 2016, 10:59:23 PM »
Nice job Jason! Always good to hear those first few pops to encourage the push to the finish line. Can't wait to see the old girl in some paint. You going for the faux antique look or the more traditional look? Paul

Offline kvom

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #37 on: August 22, 2016, 11:41:24 PM »
I hadn't noticed this build in the past, but read through it all today.  Lots of good techniques on display.   :cheers:

Offline Dave Otto

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #38 on: August 23, 2016, 12:31:51 AM »
Nice update Jason; she's looking good!

Dave

Offline Don1966

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Re: 1/3rd Scale Allman Vertical Engine
« Reply #39 on: August 23, 2016, 01:36:06 AM »
She's really turning into an interesting engine Jason and you work is always tops mate....... :praise2:

Don

 

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