# Another Oscillator!



## NickG (Dec 19, 2008)

After seeing Metal Mickey's post on his twin wobblers for presents (thanks for the idea), I thought it was such a good idea I decided to set about designing a simple oscillating engine that I can make very quickly (hopefully!). My eldest son is 2 years and 9 months old and is obsessed with my other oscllating engine so I think it would be a great Christmas present to give him his own ... and it won't matter if he breaks it! I also have a 5 month old son so I'd better make him one at the same time, the idea is to mount them on some nice wood with a brass plaque with each of their names engraved ... not 100% confident I'll get that done though, I am running out of time and haven't even started yet!

Anyway, thanks to Metal Mickey for the idea, below are some snapshots of the 3D CAD Model, I am reluctant to put the drawings up on here in case there is an error somewhere, once I have made one though, people are quite welcome to have copies of the drawings. I'm going to try to take photos of me building these two ... not done this before though so it could be a bit of a mess!

Hopefully I will make a start on them tonight ... will update on progress tomorrow, if there is any!

Nick

ps the cylinder spring, nuts, steam inlet and mounting holes are not shown - I must have got bored by that stage! Cylinder cover, pivot pin and crank pin are all going to be soft soldered in place.


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## SignalFailure (Dec 20, 2008)

Nick, I'd thread the crank pin and pivot pins rather than soldering them as I think you'd have more chance of getting them perpendicular to the crank disc and cylinder.

How are you going to make the frame, bend it or mill from solid?


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## Metal Mickey (Dec 20, 2008)

Nick, you are too kind! I do like the simplicity of look of the main frame. Nice. :bow:

Have you thought of using a larger piston or is there a technical reason for the small piston? 

For the more experienced members (or anybody really) I would like to learn your views on small versus larger diameter pistons with regards to running with say an aquarium pump. I suppose its a question of volume versus pressure. I know that in steam the 2 cylinder chest has a small and large piston with high pressure steam going into the small cylinder then the exhaust from that sent to the large diameter cylinder.

To me that seems to say that a large area should perform better with low pressure? Or am I completely off track (excuse the pun). I have started a design of my own which will be a new thread for me, but this question is making me consider two different cylinder sizes........

Nick I think your doing a great thing and I will follow your design and build avidly. Good luck. Metal Mickey.


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## NickG (Dec 22, 2008)

Paul, thanks for your comments. It's interesting what you mentioned about getting the crank pin and pivot pin perpendicular. I've made quite a few of these engines and always threaded the crank pin and pivot pin, however more often than not I've struggled to get them in perpendicular. 

I think it's more difficult to get them perpendicular when threading as it's introducing another element of error, it's not easy to put a straight thread on a small diameter. In the past, results have been acceptable as there is the option to tweak it by gently bending it afterwards.

It was for this reason I decided to have a go at soldering them in ... this way I can drill the holes and make the pins with an accurate location diameter to fit into the holes. This may have the disadvantage though that it can't be tweaked afterwards ... once it's soldered it's staying where it is, bending it may crack the joint.

Hmm, not quite sure which way to go now, I might try soldering method, just because I haven't done it that way before. On my hot air engine, I machined the crank from the solid to ensure everything was square, but that was a labourious task and this engine is meant to be simple!

The frame will be bent around a block of wood. 

I should point out that this design is based on the first ever engine I made when I was 14, which was in Model Engineer Magazine. The engine ran, but on 40 psi and snapped the crank pin!!! Differences were that it had a cylinder made from round bar which was drilled off centre in the lathe by putting packing under one of the 3 jaws in the chuck. Then transferred to the 4 jaw and the side faced off, I find it easier to use square bar. The other thing it had was a tubular bearing between the frame, soldered in place. I guess this stiffened the thing up too but I think it will be ok without.

My intention was to make a very small engine, I should have mentioned some sizes ... the bore is 3/16" and stroke 1/2". The bore is about as big as I can get with that size cylinder, as there needs to be room to drill the hole for the pivot pin without breaking through.

I've often had this debate in my mind about piston bore vs stroke & volume. My feelings are the same, the compound engine does illustrate your point, if you're operating on low pressure, the best way to go is to have a larger area since pressure = force / area, therefore force = pressure x area. You're quite right though, it's a balance with volume, if the compressor you're using can't supply the volume required it won't work either! So to get one to work from an aquarium pump, I think you'd probably end up with something with a relatively large bore and short stroke.

Actually, as I'm writing this, I'm not sure if what I was about to say is correct, so am going to have to do some more maths on the subject. I was about to say that it's more beneficial to increase the bore than the stroke .. it is, but the down side is the swept volume increases more by doing that. So two engines with the same swept volume should have the same maxium torque at the crank, that's at 90 degree crank angle, not sure about all the other angles without doing a few calculations to confirm, can't quite get my head around it!

Nevertheless, there are still a few balances to be struck. having too short a stroke would mean the cylinder was not oscillating enough to get big enough inlet and exhaust ports. I believe the placement of these is also critical, if the ports are too far apart, there will be a period of time just after top dead centre where no air is getting into the cylinder. The inlet should be just starting to open just after top dead centre, this means the gap between the centres of the ports should be 2 x port width. If they are closer, there will be overlap so periods where air / steam is going from inlet straight out of exhaust. This distance is controlled both by the stroke (crank throw) and piston rod length. 

Port sizes are also critical, not sure what the optimum is, just big enough the flow the air without restrictions I assume, or as big as possible within the particular design scheme.

I think it would be interesting to make two engines of the same swept volume, on with a large bore and short stroke and visa versa. I think they should perform roughly the same, however, the only disadvantage of the long stroke version may be more frictional loses due to having to make the cylinder oscillate more.

Does anybody else have any thoughts on this?

Should start building tonight .. honest!


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## mklotz (Dec 22, 2008)

Nick,

One thing bothers me about your design.

The two holes for the crankshaft in the frame will have to be drilled after the frame is bent. Given the springiness of the frame, both while drilling the holes and the "relaxation" after, are an invitation to misalignment and consequent friction. You might want to consider making the frame from solid.

It's not good engineering practice to depend on threads for alignment. I would drill a pivot pin sized hole into the cylinder and then counterbore it to a shallow depth. The hole aligns the pin and the counterbore gives you a place to solder without interfering with the seal of the cylinder against the standard. If you intend to run the engine on steam at some point, be careful to use at least a silver-bearing soft solder lest the steam heat cause your engine to dissolve. If the engine will always be run on air then you can forget the counterbore and use Loctite to secure the pivot pin in the hole.

The crankpin can be threaded into the crank disk if you make it in the form of a shoulder bolt so the shoulder establishes the alignment and the thread merely holds it in place. Many of my engines are done that way so I know from experience that it's a workable solution.


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## NickG (Dec 22, 2008)

Marv,

That is a very good point, I thought I'd drill it after the frame was bent, however, I think you're right, the springiness when drilling will cause the holes to become misaligned. This is probably why the original design had a tubular bearing. Might have to go down that route, the only reason I dismissed it was to have 1 less component.

Good advice with the counterbore, I was just going to counter sink slightly for the solder to filet into as there is a relief on the frame anyway. This engine will only ever be run on air though so would use loctite if I had any. I really need to stock up on some of the basic model engineering items!

Again, with the crankpin, It was just going to be a plain diameter soft soldered into place to keep it quick and simple, however, if I was doing an engine on a slightly large scale I would use your solution as it is a far better engineering practice. I am not usually one for soldering or loctiting parts and I designed my other osciallating engine to be assembled with without those methods, but on this occasion ease and speed are the name of the game.

I am slightly worried about the frame springing, however, I may get around this If I use the block of wood it was formed around to keep the sides apart whilst drilling. If not, I will have to make a bearing tube.

Thanks again for the advice.

Nick


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## mklotz (Dec 22, 2008)

Once you've bent the metal, the wooden form will only fit loosely in the engine base so the base will still be free to misalign while drilling. A bearing tube will definitely help. I understand your desire to simplify but remember Einstein's words, "Make things as simple as possible, but no simpler."

Every shop can benefit from Loctite. Their blue threadlocker is essential and their green "Press Fit Assist" (609 IIRC) will hold as well as solder. Purists may eschew the use of adhesives but I remember a quote of famed woodworker Sam Maloof, "If Holzapfel had had a router, he would have used it."

Consider machining your crankpin with a reduced diameter tenon that goes into the hole in the crank disk. That way the shoulder provides the orthogonality in the same way that my aforementioned shoulder bolt would. Clamp it in place when you solder (or Loctite) it so it doesn't droop under the force of gravity.


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## SignalFailure (Dec 22, 2008)

mklotz  said:
			
		

> It's not good engineering practice to depend on threads for alignment. I would drill a pivot pin sized hole into the cylinder and then counterbore it to a shallow depth...



Marv,

Surely there's _almost_ as much margin for error there as you'd have to get the hole exactly perpendicular, the pin a precise fit and ensure that there's no distortion when soldering? You might also have a fillet of solder to remove around the bottom of the pin which might be fiddly! 

Nick,

Have a look at the plans for the second engine down on the left-hand side of this page... http://jpduval.free.fr/Plans_moteurs_vapeur_p1.htm ... it would be easy to tun it through 90 degrees!


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## mklotz (Dec 22, 2008)

Paul,

Yes, one needs to drill the hole square - but that's equally true if it's threaded. The counterbore is meant to provide a place for the solder fillet so it won't interfere with the sealing of the cylinder against the standard. Distortion isn't much of a problem with soft solder but, regardless, he says he'll run on air so Loctite can be used in place of solder.


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## NickG (Dec 23, 2008)

Paul,

There is a clearance between the big end and crankdisc which will be big enough for the fillet of solder. 

When the engine is made and tested, I will update the drawings to suit the practices I used to make the working engine, I may have to change a few things along the way, so will see what happens!

Anyway, I have finally made a start on it, however, I should point out that unless I have a very busy Christmas Eve in the workshop, this is going to be a late Christmas present! Please see some progress below, I may have gone into too much detail to start off with here so will have to review the way I am going to present this!

Well, first of all, I think this lot will need tidying a little!






This was partly to blame ... the caput starter motor from my Renault 5 GT Turbo, think I've sorted it but that's another story and another project! The rest of the mess on the lathe was due to a favour I did for someone at work ... turning down a 2" diameter lump of mild steel, counter bored at one end and cross drilled, then parted off. Except I couldn't part it off as I didn't have a good enough grip on it, so had to saw it by hand with a very used hacksaw blade!  Anyway, no more digression from now on, I promise!






After / inbetween tidying up, I found some materials ... probably not what I state on the drawings but not too bothered. The drawings state what the materials should be, I use what I have! The brass plate is for the frame, mild steel for crankshaft, round brass for piston / cyl. cover, square brass for cylinder and I found some cast gunmetal bar which I will use for the flywheel. Copper pipe is for inlet / exhaust, bronze bar was going to be for crankpin / cyl. pivot rod but I wasn't thinking straight, I will use some mild steel. I would usually use silver steel for that sort of thing but not sure how well it will solder to brass and I find it's a pain to turn at very small diameters (as Marv says, I could use loctite but don't have any ... could even use araldite, that's strong stuff but need to make sure it stays where it's meant to!






I started on the flywheel as I'm not keen on sheet metal work, I find that boring!

Gunmetal chucked, faced and OD roughed. I noticed there are some blow holes even this far under the surface of the casting ... hopefully they would disappear as I got to finished diameter. The surface finish wasn't quite as good as I'd have liked as I was using a cutting tool with wrong radius and rake angle really, the reason for this was to try and use the same cutting tool all the way through to save set up time ... this could backfire!






Turned to finished OD and the boss machined, ready to centre drill, drill (I'm not superstitious but why did it have to be No. 13 drill that I needed before reaming!) and ream for crankshaft hole.






Successfully parted off (or is it? You can see component underneath bed!) under power cross-feed. I have found setting the feed to slowest and spindle speed about 200rpm works best for me. Gives a nice constant feed, better than I can do by hand.






At this point I was considering leaving the flywheel as it was because I knew I'd have problems putting it back in the chuck (my 3 jaw is very worn). However, I decided to go ahead and try to make it how I'd designed it as there were some chatter marks from the parting tool so I at least needed to skim it. Luckily the first place I gripped it, it appeard to be running ture!I started trying to counterbore but ran into problems. There wasn't enough clearance around the tool so as I got deeper, it started catching the edge of the hole. So my plan had backfired, I needed to change the cutting tool! This chafing also had the effect of moving the flywheel in the chuck ... d'oh! 






After grinding trying another cutting tool and messing it up even more, I decided to grind one properly which gave good results.






I was quite chuffed until I looked at the rear ... the chuck jaws have quite badly marked the boss (can't see on this photo), I've dressed with a needle file and it'll do, but I always get this problem, does anybody have any advice concerning this? Other than that, fairly pleased, just need to drill and tap the hole for the grub screw. I've put 6ba on the drawing but not sure whether this may be too big, might go for 8ba.






I think I've made this far too detailed ... all this for a flywheel! :-[ From now on I'll just post a couple of pics on each component with less waffle! Oh, forgot to say, there is still some very slight evidence of blowholes so it obviously isn't a great piece of gunmetal.

Crankshaft and frame will be next, not sure whether I'll get anything done tomorrow though!

If anybody has any suggestions on the way I'm posting I'll be happy to take the advice as clearly I haven't done this before!

If I don't get on here tomorrow, Merry Christmas to all, I hope everybody has a good day.

Nick


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## Maryak (Dec 23, 2008)

NickG  said:
			
		

> I was quite chuffed until I looked at the rear ... the chuck jaws have quite badly marked the boss (can't see on this photo), I've dressed with a needle file and it'll do, but I always get this problem, does anybody have any advice concerning this?



Nick,

Two possibilities, one don't tighten the chuck too much and take light cuts, two cut up an aluminium soft drink, (or better beer after emptying in the approved manner),can and wrap a piece around the part to be held in the chuck jaws. Electrical plastic conduit is also good near the same diameter. 
	

	
	
		
		

		
		
	


	




 that's three :

Hope this helps ??? ???

Best Regards
Bob


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## SignalFailure (Dec 24, 2008)

Quick reply as last minute xmas shopping required (!).....

I wrap a bit of oily paper around stuff to avoid marking it.

Looks like a good start to me Nick.


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## NickG (Dec 24, 2008)

Ah, good ideas chaps, thanks, will definitely try those!


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## SignalFailure (Dec 24, 2008)

I've also used electrical tape and even thin wet and dry paper!


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## mklotz (Dec 24, 2008)

On the matter of the chuck marking the workpiece when clamping on machined surfaces...

Bob has already described the most expedient solution - never throw away an empty soft drink can. The material therein is ideal for all sorts of shimming and protection uses.

Just for completeness sake, I'd like to add two somewhat more complex ways of managing the problem.

With a bit of ingenuity you can cut shapes that will fit over the chuck jaws from light copper sheet. Mine are equipped with tabs that hold them in place even when there is nothing being clamped in the jaws. This technique is particularly helpful when clamping non-cylindrical parts in the 4jaw - especially for those of us who only have two hands.

A collet chuck is the ideal solution to this problem but that can get expensive. However, you can make your own collets which is a particularly good idea if making a number of identical parts. Machine a top-hat shaped piece of aluminum and bore it out to the size of your workpiece. Then slit it lengthwise with a hacksaw or endmill so the chuck jaws can compress it. The "brim" on this impromptu collet will prevent it from sliding back into the chuck jaws.


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## Metal Mickey (Dec 24, 2008)

Nick, for mine I used aluminum and bored it out to suit the boss, like a tube really and then cut 3 slots at 120 degrees at each end to half way ish, with the slots at a different start point. Sounds horrible from here but it is quite simple to make. You can tighten you chuck then as much as you want.

I never throw them in the scrap bin as its amazing how many times you make things around the same sizes. 

Mike


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## NickG (Dec 25, 2008)

Thanks guys, these are the practices I really need to start adopting to start producing some good quality work!


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## NickG (Dec 29, 2008)

???   :'( Just spend an hour writing an update and it didn't post, now all work is gone!


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## NickG (Dec 29, 2008)

I can't possibly remember what I wrote and am so annoyed right now but here are the key points!

I have made more progress, finished flywheel, made crankshaft and made cylinder.

Flywheel - changed from 6ba to 8ba for grub screw ... I thought 6 would look too big. I used a hex head bolt as don't think I have a grub screw but it looks OK.

Crankshaft - Simple turning, parting off and drilling for crankpin ... well it should have been. I used the tailstock centre but think this has given it a very slight taper, prob my tailstock isn't aligned properly. Shouldn't cause a problem though. Another annoyance was not being able to get into the work piece enough with the cutting tool to get the square faces. I should really grind up a standard set of tools and put aside associated packing pieces as it would save a lot of time, would love a quick change tool post with holders! Another problem came when parting off, I tried to be clever and set a very slight angle on tool to get a good surface finish on the crankdisc face ... big mistake as it started to chatter on the other side. At which point I got scared and got the hacksaw out! Soldering the crank pin in was OK, however I remembered why I don't like it, it's hard and time consuming to clean components up afterwards. I should have got some loctite or reverted to threading.

Cylinder - This went well by comparison. Marked out brass, squared up and milled to length in my new (well, unused since I bought in summer) chinese milling machine. At this point I realised the handwheel graduations are quite accurate so used those to get coordinates for holes, confirmed by the marking. For the pivot pin I centre drilled, opened up and finished with 1/8" end mill to get a flat bottomed hole. The mill has a DRO on the spindle so used that ... not sure whether it's accurate or not, will have to try measuring! Then flipped the cylinder vertically in vice, got coords, centre drilled, drilled No. 14 then reamed 3/16" at a slow speed with plenty of oil. The port face was then lapped on emery cloth, then with oil, then oil stone, this has always worked well enough for me in the past. Some of you will notice that I did all the drilling work with ER collets, that is because the chuck supplied has a min dia of 5mm! It's huge! Probably a good thing though as the cheap chinese collets (about £30 from ebay for chuck, collets and carriage from china!) kept everything running nice and true.

Here are pics:

Turning crankshaft down to size




Test fit of flywheel




Reversed in chuck to face disc after sawing off!




Finished crankshaft, looks OK.




Set-up for soldering, not good practice but worked for these small components




Finished crankdisc and crankpin assembly after cleaning up




Crankshaft / Flywheel assembly




Set-up in milling machine for drilling holes, had previously squared ends and milled to length




Flipped vertically in vice to centre drill and drill bore




Reaming bore




Finished cylinder after lapping. Countersink on pivot hole was done with no 1 drill by hand for solder to run into. Countersink on port was a mistake after centre drilling too far. THis may cause slight overlap of ports at TDC but don't think it'll affect it much.




Well, I better go, will be in trouble with the wife for writing all this twice! Just got the frame, piston, pivot pin and cyl cover to do ... oh and the base .. I always discount the base and always mess it up, making the rest of the engine look worse!

Hopefully over the coming few days I will bring you the final installments and fingers crossed a running engine!

Thanks for any interest, I am aware this is pretty insignificant by comparisson with a lot of projects on here!

Nick


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## ksouers (Dec 29, 2008)

NickG  said:
			
		

> Thanks for any interest, I am aware this is pretty insignificant by comparisson with a lot of projects on here!
> 
> Nick



Nick,

NO project is insignificant. Lots of people are interested in others projects. They do read them. One never knows what bit of insight might arise out of a project. For example, your bit about chamfering the port. I had never considered how that might affect timing before you brought it up. Now I will.

As for the rest of the project, can't wait to see it finished and running. Nice work.


Cheer,
Kevin


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## stevehuckss396 (Dec 29, 2008)

NickG  said:
			
		

> Thanks for any interest, I am aware this is pretty insignificant by comparisson with a lot of projects on here!
> 
> Nick



No its not, I love small engines. Keep sending the photos!


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## NickG (Dec 29, 2008)

Cheers guys! Yes, the posts on here are excellent and as you say, usually insight does arise so we can all learn lessons as well as different techniques.

My intention for this one is to turn it into another simple oscillating engine for the beginner, although there are probably already a lot of designs out there!

Nick


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## mklotz (Dec 29, 2008)

Nick,

Re the frustration of losing a lengthy post...

A good approach is to get a separate editor program and, when you intend to write a lengthy post, do it in this editor rather than in the "reply" function available on the forum.

Then, when your reply is complete, use the clipboard to copy it into the "reply" section. That way, if something runs amok, you still have the copy in the editor and it's a simple task to copy it for another try at posting.

Some editors will have the facility to do automatic saves of your work at timed intervals. This provides further insurance should your computer lose power while you're typing.

Unless my reply is only going to be a sentence or two, I never type directly into the reply box. 

Also, let me echo Kevin's reply. No work is insignificant! The fact that it's important and satisfying to *you* is more than enough justification for posting it but, beyond that, you can't anticipate what others, both current readers and future, will learn from what you post.

Many of us who indulge in this obscure hobby have no one local to appreciate or comment knowingly on the work we do. One of the most important reasons for the existence of this forum is to provide a means of doing exactly that.


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## shred (Dec 29, 2008)

Why do I always end up "2nd"-ing Marv's posts?? ;D

Sometimes the 'back' button and or trying to post again can recover previously lost text, but it's iffy. 

Anyway, some of the very basic stuff is whats most needed at getting new builders going and old hands unstuck (and I put myself firmly in the first category). A few months ago I was looking for some basic info that was so obvious to anybody that had done it that they never described how to do it. It wasn't until I found an article by a new builder that explained doing it that it made sense.

I've ranted several times about how the lack of introductory information is a barrier to entry in these hobbies. 
This site is turning in to a great resource for that information and encouragement. ("That's written up in the March 1957 issue of MEWE" may be a good answer, but it's not a useful one for many many newcomers.)


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## Maryak (Dec 29, 2008)

Nick,

Your doing great work here :bow:

Please don't beat yourself up, your project is SIGNIFICANT in and of itself. Sharing it with the rest of us demonstrates a significant amount of trust on your part and helps all of us to better enjoy our hobby as we learn from each other.

Enough from the armchair philosopher 
	

	
	
		
		

		
			





Keep Dem Piccys coming 
	

	
	
		
		

		
		
	


	




Best Regards
Bob


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## rleete (Dec 29, 2008)

NickG  said:
			
		

> Thanks for any interest, I am aware this is pretty insignificant by comparisson with a lot of projects on here!



I know exactly how you feel. No matter how much sweat and tears you put into _any_ hobby, there is always someone out there that is going to be able to outshine your best effort. DON'T let that stop you posting your own creations. It may not be perfect, but it keeps the new guys like me motivated to produce our own.

And, if you happen to get good enough to make a shining masterpeice, it only goes to show what can be accomplished.


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## NickG (Dec 29, 2008)

Thanks for all your support guys, to be honest, I did wonder before posting information on this build whether to bother, but Im glad I did now for the reasons people have mentioned. It can be daunting for the beginner on here seeing all these wonderful creations so if this encourages more beginners to post that would be an added bonus. 

Although this is probably the most primitive of engines, I am still learning things in building it. Ive built what must be into double figures of this sort of engine since I started out in the hobby 15 years ago, but I feel that this one and my previous two engines (hot air engine and another oscillator) have taught me a lot and (fingers crossed) I think this current build should technically be my best yet. I feel like Im continuously improving and sharing my build, warts and all, can only help further as I like many others aspire to produce some of the excellent models shown on this forum.

Marv, thanks for the advice Re typing this into an editor. This has happened to me in the past but as Shred said, before I was lucky and it was still there when I clicked the back button. This time it had some sort of communication error; hence I am typing this into MS Word! At least this way if the Internet messes up Word should still be OK.

Tonight I made the piston / rod / big end combination. In the past I have made these separately but I wanted to turn this from one piece to cut down on time and sources of possible error.

There isnt a lot to report really, it went very well indeed so I will just put up the photos with brief descriptions of what I was doing.

Brass piston / rod / big end chucked and turning down to size





Right hand end down to size and test fit in cylinder  I was getting a good surface finish straight from the tool on the finest feed so I didnt bother lapping as I thought it might take away its parallelism, an excellent fit in the cylinder was achieved, probably the best Ive ever had.





The waist was then narrowed down where it just had the piston rod function. I then had to grind a right-handed turning tool to do the other end!





Work-piece was then parted off. I didnt want to risk putting back in chuck to face other end so the inevitable pip that was left was filed off with a needle file.





Test fit in the cylinder. This is definitely the best cylinder / piston combination I have made. The finish doesnt look great in the picture but its very close up. The piston slides right through with the same resistance all the way and very little play. It paid off taking very light cuts and taking more passes at the same setting. Usually Im a bit inpatient and end up with a sloppier fit than Id like!





Set-up for drilling the big end - this was a bit scary but was the only real way I could think of. Worked very well, just had to be really careful.





Finished piston / rod / big end.





Trial assembly of all components so far. They have gone together very well and am quite please with these parts.





So all I have left to do is the frame, cylinder cover and pivot pin. The frame is critical and I think is going to be quite a tedious job! The other two should be easy, providing the pivot pin goes in square and solders OK. Oh, Ill have the pipe work to do and of course the base! So another few nights should hopefully see a running engine!

Nick


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## NickG (Dec 31, 2008)

Hi all, another instalment of the simple oscillating engine (I should really change the title, I didnt think Id make two of them!)

Last night I did the cylinder cover, not much to report there except I got a little impatient and the register that fits into the cylinder bore ended up a little small. It was supposed to be a tight fit but ended up a loose one. No harm done though, it just meant I had to clamp it when soldering. The usual problem of the pip after parting presented itself so that was just filed down after soldering.

I also made the pivot pin. Originally I was going to make it from this phosphor bronze, but that was flexing too much in the chuck (my chuck isnt very good at holding small diameters). So, I found a piece of ¼ hexagonal steel to turn it from. This was much more rigid. Again, my impatience showed (I really have to conquer that) and I ruined the first attempt, making it too loose a fit in the cylinder pivot hole. The next one I made the perfect size  a nice tight push fit. I kept testing the cylinder on it to ensure the right fit. Doing it this way meant I had to turn the narrower section for the thread at the chuck end. There was little point trying to part off with such a small diameter so I hack-sawed it off and filed the end square before threading. This worked very well.

All there was left was to solder the pivot pin in. I gently pressed it home in the vice, checked with square and it is as square as I could possibly get. Probably the best Ive ever done. I used this solder paste stuff, more as a flux than anything else, taking care not to get it anywhere I didnt want solder. Then just a dab of electrical soft solder into the counter sink and it flashed around the joint. I was very pleased with the result. 

Cylinder cover turned and ready to part off





Cylinder cover clamped and soldered in place





Turning pivot pin





Test fit of cylinder on pivot pin





Cutting thread on pivot pin





Finished pivot pin





Pivot pin pressed into cylinder and checking for squareness





Pivot pin soldered in place and cleaned up





Sorry about the quality of these photos, not sure whether the camera is playing up or I'm just doing it wrong!

Well, theres only the frame left to do, probably the most challenging component. Of course I need to make something to mount it on and some inlet pipes. These always tend to be afterthoughts in my projects and never live up to the rest of the engine!

Nick

Ps Hope everyone has a good night, I havent got anything planned but doubt if Ill get away with being in the garage all night!


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## Maryak (Dec 31, 2008)

Way to go Nick,

Not sure my old instructors would have given me a tick for using tool makers clamps for soldering.........but if it's all you have available........ then needs must.

Best Regards
Bob


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## NickG (Jan 1, 2009)

Thanks Bob, I know, I couldn't think of another quick way really, suppose I could have wired it to hold in place but I knew I'd be able to get enough heat into it despite the clamp being a big heat sink!

Think I've worked out the best way to do the frame now, it should be OK.

Nick


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## NickG (Jan 3, 2009)

On New Years Day I set about making the frame for the engine.

First I thought Id mill a block of wood to 1 to bend it around  this turned out to be a pointless waste of time. Bending the frame proved very difficult indeed and I wouldnt recommend it! I should have taken peoples advice and designed the frame differently but at least I have learnt from this experience! I remember making oscillators with bent frames for my very first two engines and couldnt remember any problems  but I dont think I paid as much attention to detail back in those days, when I was 15, if it ran, that was everything!

I started bending the frame and quickly realised that I hadnt gone about it in the right way. The wood might have worked, but because I didnt have the bend line level with the back jaw of the vice, it started to bend about the rear vice jaw as well as the wood. Also, the wood crushed, but I expected that and was hoping that would give a decent radius. I had become very annoyed with myself by this point and tried in desperation to anneal the brass with my micro torch, to no avail! (I really need to get some workshop essentials sorted out) I resorted to bending it around a square bit of metal, this has dug into the brass slightly and not really given a constant radius due to starting with the wood. I then had the problem that I couldnt grip the brass whilst bending the other upright. By this point I was even more frustrated, so after lots of swearing, hammering, tweaking and using packing tools that came with the milling clap set (they were 1 wide) to bend it around Ive produced a somewhat dodgy frame with different radii at each side and quite deep marks where the metal has cut into the brass. 

Im not very happy with it and wouldnt do it again this way. I would either use two straight pieces of brass with a spacing piece at the bottom, which the uprights would be bolted to. Or, use a piece of brass angle and a bearing tube soldered in, converting the engine into a horizontal layout. The other option would be to do it as per my other oscillator with angle at the bottom supporting the upright and a bearing tube.

Having said that, if the bent frame would work if it were done properly, with care. I.e. anneal the brass before each bend & make a proper hardwood or metal former. But this defeats the object of making the frame just 1 component, as another is required to make it! If more than one frame was being made, some sort of jig could be made, but for a one off its not worth it.

Perhaps I need to read Marv's advice again and take heed ... 





> I understand your desire to simplify but remember Einstein's words, "Make things as simple as possible, but no simpler."



Milling wood down to bend frame around.





Cutting frame material the old fashioned way with a blunt hacksaw blade (this would be much less time consuming if I had ½ x 1/8 brass but I didnt!





Milling frame material to get parallel & down to ½ wide.





Lining up in vice ready to bend.





Disaster!





Frame in vice on milling machine ready to drill ports, pivot hole, main bearings and mill recess. Had previously milled both uprights to height.





Holes opened out to right sizes and recess milled. The bearings were also reamed to size. The only problem I had was getting the right sized pivot hole. 1/8 was too small since I had made the pivot rod a tight fit in the cylinder, one number drill was too small, the next was a little sloppy, but I had to go with that. Its ok though, just slightly looser than I would have liked but it will take account for any misalignment.





Picture showing reamer going through both bearing holes. I didnt have any problem doing this since both uprights were clamped firm by the milling vice in their natural position. Just went fairly lightly with the drill.





Finished frame cleaned up, its not good but Im not doing another! I will learn from my mistakes on the next project! With a bit more fiddling and filing etc. it might improve.





All the engine parts, just the inlet pipe and base to do.





The assembled engine, spring is too big, have got one from a pen now. It seems to turn over very nicely with no tight spots and makes little whooshing noises from the ports. When putting the crank at 90 deg the ports line up exactly which is a good sign too, I think the engine should work very well.






Hopefully will bring you a running engine with a video very soon, although not sure how Im going to run it yet as dont have my own compressor! Car tyre compressor might work?

Nick


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## mklotz (Jan 3, 2009)

Nick,

Nice work so far. I'm glad you finally got it bent.

A car tire compressor will work (that's how I aired my first oscillator) but they're noisy as hell!

If you're going to be building smallish engines and don't want to invest in a full-sized shop compressor, consider getting a small airbrush compressor. That's what I use for all my air-powered engines. Here in the States they can be had from Harbor Freight for around $50.

At your local pet supply store you should be able to find 3/16" ID silicone tubing used for air supply in aquariums. It's a nice match for both the engines and the airbrush compressor.

Aquarium air pumps are also a possibility but I've never had much success with them. A few will develop adequate pressure for a tiny engine but the ones I've tried couldn't deliver much volume. YMMV.


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## rleete (Jan 3, 2009)

NickG  said:
			
		

> Ive produced a somewhat dodgy frame...Im not very happy with it and wouldnt do it again this way.



I think you've fallen into the trap most of us do. If it isn't perfect, it isn't good enough. Not that you couldn't do better, or not that you can't improve, but it looks fine to me. Polish it up a bit, and call it a learning experience.


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## Metal Mickey (Jan 3, 2009)

I must say thats really looking good. Most impressed! Looking forward to seeing the video of them running. Metal Mickey.


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## NickG (Jan 3, 2009)

Marv,

Yes, the car tyre pumps are very noisy, I recently took one apart and was amazed to see the tiny bore, stroke and motor geared right down, but I suppose they have to be that way. They don't deliver much volume either. 

Are the small airbrush type compressors fairly quiet? Talking about that reminds me, we used to have one of those black and decker type compressors that you hooked your drill up to, which would be very noisy but if mounted with a suitable motor instead it might be ok. It would need a tank though, so by the time I've turned my Dads garage upside down to find it and got some sort of tank it'd be easier just to by the sort you are talking about.

I have heard some people use old fridge compressors, are those any good for the job? 

Many years ago I played around with an aquarium pump, it was pretty much a wobbler being driven by a motor. I think it was twin cylinder, but only single acting and relatively slow running so the air would have been delivered in quite distinct pulses which wouldn't help. Also, as you say, very small volume delivered.

It might run for a few seconds off a balloon if I can squeeze it enough without bursting it! Would be a laugh to try it!

I think when this one is complete, I will draw 2 more parts; a brass angle and tube bearing, keeping all the other parts the same, that will give me a horizontal version that is easier to make!

Mike, my intention was to make a pair of these, but I decided just to make one, partly incase it was rubbish and partly because I was running out of time, as it turns out I've gone way way over my initial time scale anyway! 

I will make the horizontal version as well though, then if all goes well, I'll put both sets drawings on here incase anybody is interested in having a go.

No more progress yet, I should be out there now really but having a break. I might do something mid-week, if not it will probably be finished next weekend now.

Thank you all for the kind comments and advice, it goes a long way, encouraging me as well as cheering me up!

Nick


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## Noitoen (Jan 4, 2009)

Hi,

For a compressor you can recycle an old refrigerator compressor. I've seen somewhere a reservoir made from a piece of high pressure pvc pipe with 2 end caps glued on. This pipe can withstand pressures of 10 Bar, so I think it's simple to build one.


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## putputman (Jan 4, 2009)

This may be another possible source for a small compresser.

My son used to work for a company that delivered oxygen and other supplies to nursing homes, hospitals, and private homes. One of the items was a "nebulizer". When the customers were done with the unit they were picked up by the company and they disposed of them. Because of state law, they could not use them on another patient.








He cleaned up several of them and gave them to me. 
They were set at differant PSI. Some were only a couple PSI and some were quite high. I use one that is set at 48 PSI to run my PM bronze Coke Bottle engine that drive a small machine shop. It is quiet and supplies enough volume to run at high speed.

All the units looked identical. It may be possible that the PSI can be adjusted interally. I never took one apart to find out.

Every large town probably has a similar business and is throwing away these units on a regular basis. Might be worth checking on.


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## mklotz (Jan 4, 2009)

The airbrush compressors are very quiet indeed. One can carry on a normal conversation with one running two feet away. Remember, they are intended to be used in a studio environment where excessive noise might be a major detraction.

They're about the size of a toaster and have no accumulator tank. IIUC, they use a diaphragm type pump. And, as I said earlier, they're very affordable.

Even if you eventually buy/make a larger conventional compressor, you may still want to consider the airbrush style. Transporting a large compressor to exhibitions that lack their own air supplies can get tiresome. Also, demoing engines on a coffee table rather than dragging them to the shop now becomes a possibility.

If you intend to build large size engines airbrush compressors may not be up to the job but, for miniature engines, they're really handy.

Resist any suggestion to use PVC for pressurized air. It is not intended for this application and can be very dangerous. If it fails, it can fracture and produce dangerous, possibly lethal, shrapnel.


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## NickG (Jan 4, 2009)

Thanks for the ideas. I wonder if these produce any decent sort of volume and pressure ... doubt it though http://cgi.ebay.co.uk/Rio-Airbrush-Tanning-with-Compressor_W0QQitemZ170273487387QQcmdZViewItemQQptZUK_Health_Tanning_RL?hash=item170273487387&_trksid=p3286.c0.m14&_trkparms=72%3A1298%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

I remember now, for my last oscillator I tested it with the CO2 bottle from my mig welder, that was OK just to see if it worked but obviously everything gets very cold and it probably wouldn't last very long. Think my bottle has run out now, never actually used it for welding other than practice runs!

Nick


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## mklotz (Jan 4, 2009)

I don't think I'd want a rechargeable compressor. Although, the opportunity to make yourself look like a refugee from South Beach while running your engine is enticing, I suppose.

This is the type I was thinking about:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93657

Note that it comes with a built-in pressure gage, regulator and water trap. British weather being what it is, you may find the latter useful.


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## NickG (Jan 4, 2009)

Haha ;D

That one looks a good buy, will have to look out for something like that, would come in very useful.

Nick


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## NickG (Jan 7, 2009)

Spent another couple of hours in the garage last night, basically finishing off the engine. It still needs a wooden base (waiting to get some nice wood from my dad's) and was thinking of putting a brass plaque on it and getting engraved with my son's name since it's supposed to be for him, or is that a bit cheesy?!

Last night I did the following:

Dismantled.

Drilled two mounting holes in the base of the frame.

Opened the inlet port out to accept the copper pipe.

Bent a piece of 1/8" OD copper pipe.

Turned a barb for the air supply. I got some dimensions from the pushchair tyre valve so that my car tyre compressor would fit!

Soldered the pipework in place.

Filed the some of the marks out of the frame and created some more!

Painted the inside dish of the flywheel red. (it's becoming a little trade mark of mine, all my flywheels are red for some reason!)

Reassembled with 3 in 1 oil.

Mounted on a scrap piece of wood.

I then tried running the engine with the tyre compressor. I have an old car battery in the garage that I haven't got around to chucking out so that was a stroke of luck! The engine ran superbly, it was flying over as expected with such as small bore and stroke, and no way to regulate the air flow. Would be interesting to see what speed it was going. It was going so fast that it didn't look like it was moving, was all a blur! Couldn't hear a lot due to the noisy compressor. What I was impressed with was how true everything was, the engine didn't shake or wobble, just ran.

I can't quite turn the engine over on lung power though, think the bore is just too small.

Sorry, I have no pictures of this, in the excitement I forgot to take the camera out with me! However, the internet at home is down in any case so I will get some pictures and a video up as soon as possible. Might get another co2 bottle to run it so we can hear the engine rather than the compressor.

To coin a phrase, I just need to give him his sunday suit now!

Nick


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## ChooChooMike (Jan 7, 2009)

mklotz  said:
			
		

> This is the type I was thinking about:
> 
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93657



That looks like the one I bought. It's a little noisy, but bearable. After a while, it gets pretty hot, almost egg-frying hot to the touch. I ran my latest engine on it for > 1 hour a couple of times to help with breaking the engine in.

It's worth the $, especially when you can find a H/F coupon to use !

Mike


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## shred (Jan 7, 2009)

NickG  said:
			
		

> I can't quite turn the engine over on lung power though, think the bore is just too small.


Somewhere I read that the lungs can only generate 1 to 2 PSI, so I wouldn't be too upset about that.


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## NickG (Jan 7, 2009)

Think I just nearly burst something trying to get it to run on lung power!  Seriously though, I think I've heard that before too about the 1-2 psi. I think if an engine was made with the right proportions it would be able to turn over by lung power. One I made years ago for my GCSE project had a 1/2" bore and 1" stroke, that was possible, you just ran out of breath after about 3 revolutions!

Here is a photo of the engine still lacking it's proper base, and a somewhat dodgy video taken by my kind wife as I operate the lashed together bicycle pump!


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## rleete (Jan 7, 2009)

Not the steadiest of hands!

Hey, it runs, and sounds good, too.  :bow:


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## cfellows (Jan 7, 2009)

rleete  said:
			
		

> Not the steadiest of hands!
> 
> .......



Hey, he was just excited, the way we all are when an engine runs for the first time! :big:

CHuck


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## NickG (Jan 8, 2009)

It was me that was making it jiggle about pumping the cycle pump! :big:

I'll have to show it running on a proper compressor once I've mounted it properly!


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## malcolmt (Jan 8, 2009)

Hi Nick
That video really made me smile, the excitement of getting your engine to run, FANTASTIC. It sounds great. 
Very well done

Kind regards

Malcolm


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## Maryak (Jan 8, 2009)

Nick,

Sounds like this 
	

	
	
		
		

		
		
	


	




 getting ready for the warm up lap. 




Best Regards
Bob


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## T70MkIII (Jan 8, 2009)

That's great Nick. I've enjoyed following your build-up.

BTW, in Pumping Iron, Franco Columbu blew up a hot water bottle until it burst with lung power alone! Can't guess what pressure that would require...


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## NickG (Jan 8, 2009)

Thanks for the kind comments and for following the thread!

I didn't really expect it to sound like that! Guess it's to do with it having a small bore and port sizes, will have to see what it's like ticking over.

Must have been quite a high pressure to burst a hot water bottle!  Wish I had a pair of lungs like that! ;D

I will be attempting my first flame licker or possibly an i.c. engine next so look out for lots of trials and tribulations coming soon! 

I will need to do the cad model and drawings first though, I used to make things off the cuff but this has proven it's worth over my last few builds so I continue with this method!

Whatever I do is likely to be a simplified version of one of Jan Ridders designs, I also like the Webster but don't feel confident enough to do the valves and cams yet for a 4 stroke.

Nick


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## NickG (Feb 2, 2009)

Hi all,

I've now made the base for this engine and done a video of it running of a car tyre compressor, so sorry about the noise! It shows about 10psi pressure on the gauge whilst running.

Nick


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## 90LX_Notch (Feb 2, 2009)

That is a very nice looking engine and a great design. It's a great engine for a newbie to build as a first engine.


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## NickG (Feb 3, 2009)

Thanks, am pleased you enjoyed building it and got a great result too!


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## Metal Mickey (Feb 3, 2009)

Well done, a nice design that works!What more can we want! MM


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## itowbig (Feb 3, 2009)

i like it. yes well done another one to add to the list


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## kustomkb (Feb 3, 2009)

Very Slick. Simple Elegance.


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