First engine, the little machine shop oscillating engine.

[metalnwood]

Hi, I decided my first engine would be a simple one and this one had a good set of drawings.

I just needed to convert a couple of things to metric and get some 6mm drill rod and I am now ready. The plans are simple enough but I have stumbled across a problem which I am sure someone can confirm for me..

There is a machine screw which goes through the upright in to the cylinder block. I guess the idea is that this with the spring has a light tension to keep the cylinder block against the upright, right? Either that or it is just providing a pivot. Either way the screw should thread in to something but on the plans I don't see a thread in the cylinder block for it or in the upright.

I am not familiar with imperial so perhaps one of these sizes is correct for a tap, not sure. Any confirmation would be appreciated,

pdf is here to have a quick look. http://littlemachineshop.com/Products/Drawings/2593OscillatingEngineAssembly.pdf

Thanks,
Jason

 

[Metal Butcher]

The part that goes in the hole on the cylinder is the pivot pin (the cylinder pivots or wobbles held against the upright (frame) with the spring. The pivot pin is usually threaded only on one end to hold the spring and spring retaining nut. This means it is (pivot pin) either soldered, press fit, or loc-tited in place. This will be a choice based on materials used, example- brass pin soldered to a brass cylinder would work well. It looks like the pivot pin in this drawing is a threaded machine screw . Not a good way to make a pivot point in my opinion, but that's what this kit/plan provides. The drawing seems to lack its (pivot pin) tapping instructions for t he cylinder, but 13# on the first page gives the thread dimensions of 10-32,

Very nice project! Please post your progress, and welcome to our forum!

-MB

 

[metalnwood]

OK, I wrote a reply with a couple more questions but then it clicked, I had understood your reply wrong..

OK, so it's soldered/pressed etc in to the cylinder block and the pin is actually rotating in the upright, not in the cylinder block, this way the spring arrangement can work.

I think I am there.. I will go and see what I can do now!

Thanks,
Jason

 

[Tin Falcon]

Jason:
The cylinder shows the hole drilled and tapped for the 10-32 machine screw. They apparently missed the hole thread call out but if you look at the drawing the hidden lines show a threaded hole. part 13 on the drawing and a through hole drilled in the upright part #1 sheet 2.
You will likely want to use an M5-.80 metric screw if you are keeping things the same size. This is very close to a 10 -32 unf

Here is a link for fractional /decimal/metric equivalents

http://littlemachineshop.com/Reference/DecEquiv.php
And a tap drill clearance drill chart in imperial and metric.
http://littlemachineshop.com/Reference/TapDrillSizes.pdf

You are correct the part 13 is indeed a pivot and the spring keeps tension between the cylinder and upright. That spind kind of also acts as a built in safety release in that the air steam leaks from between the cylinder and block usually around 30 psi on most oscillators.

An alternate method as suggested by MB would be to solder a pin in and thread the outer end and use a nut but that will not work with aluminum witch is the specified material for the cylinder. You would have to change the cylinder to brass.


The pivot does indeed move in relationship to the upright and is solid in the cylinder but it certainly can be threaded in you may need a dab of light grade lock tight .
Hope this helps
Tin

 

[black85vette]

Looks like they have two versions. I remembered using their instructions when I built mine so I went back and looked for it. Here is the file with the instructions and plans. It has the 10-32 call out for the cylinder.

View attachment 2593OscillatingEngineAssembly.pdf

 

[metalnwood]

Thanks guys, well here is the start of the pictures.

You guys seem to like pics of the same things over and over and I must admit that I never get bored looking at things set up on the lathe and mill.

So lets start with a boring one.. I roughly cut the stock on the bandsaw and milled them to size. Then tapped drilled etc and I now have the base and upright. The upright needs to be finished of course.

It was a bit of a mission to start as I had the dividing head set up so that needed to go, put the vise on and square that up. I was stumped when I was at the bansdaw because the table looked like it was on an angle. I looked and it wasnt so I cut but my eye kept telling me it was out.

Then when I went to remove the dividing head from the mill I put it on it's table which looked to be sagging in the middle. Very strange as I made it from steel and theres never enough weight on it for that..

Then I realised. My 2yr old broke my glasses and they currently sit on my nose at an angle, they were making everything seem bent! I hand't noticed it until I got to the workshop where there are so many things you want straight!


I need to finish the milling before I do the turning as I may need to set up the dividing head again at anytime.

Jason

 

[Twmaster]

And off to a good start!

 

[zeeprogrammer]

Great start metalnwood. Looking forward to more.
Speaking of 'looking', I know what you mean about glasses. I have a magnifying glass on my portable light...drives me nuts...I'm always thinking my mill is out of tram. :big:

 

[arnoldb]

Welcome to HMEM & a good start metalnwood. A sensible choice for a first build engine as well.

Don't let the imperial measurements put you off; you'll soon get used to converting it.
I also have metric equipment for the most part; what I do when I get an imperial plan is I print it out, and sit down with a calculator and convert all the dimensions to their closest metric equivalents. On these wobbler engines most of the dimensions are not too critical. The only areas you need to take care of when converting are mating parts (shafts & bushes, cylinder & piston etc.) For example, if a shaft is specified as 1/4" and you make it 6mm, you have to make sure that any holes/bushes the shaft will go through are also made 6mm (actually something like 6.05mm for a running fit) and the hole in the flywheel that goes on the shaft is also made 6mm.

Keep a cheap & cheerful pocket calculator around the shop; makes life a lot easier. Most digital calipers can switch between metric/imperial, making conversion very easy.

Regards, Arnold

 

[metalnwood]

Thanks Arnold. I am actually quite used to working in imperial.

Although New Zealand is metric you just can't get away from imperial when dealing with plans from the states. You are right, the only time it get's tricky is when I want to use metric fasteners and I need to adjust other dimensions for that.

I need to look things up because I am not used to things like a number 10 drill which doesn't even tell you the maximum diamter. From that point of view having an M6 that means the diameter is 6 is kind of helpful

No problems though. I just finished the cylinder. I wish I had 1" square stock to begin with but I only had 2" square so I cut it down on the bandsaw first. That was getting hot!

It's getting bed time over here so I will continue tomorrow if the kids let me.

Jason

 

[metalnwood]

What a wally, never take a mill to something after breakfast without looking at the plans!

I looked at my cylinder and saw the M5 thread I had tapped and thought, why didn't I bore that all the way through? So I went down and put a 3.3mm drill in and drilled all the way through. Next I went looking for the air intake to thread in, it was gone! I looked further and found it screwed in to the upright, then it hit me I was machining the right thing on the wrong part.. argh.

This is why I was looking at it thinking I was sure I had done it and I had, in the right place! No matter, the one I screwed up was for the pivot pin so I will put a bit of sealant in when I put it together so the air wont escape. I cant imagine a little hole in the side of the wall will impact things..


Bummer though..

Jason

 

[metalnwood]

I can only laugh at myself now! I am trying to get through this too quickly and am screwing things up as I go, basic mistakes..

I didn't mention that when I bored the cylinder on the mill with a boring head I went oversize by accident, I hadnt used the boring head for a little while and I forgot how many turns I needed for the diameter.. So in a rough pass I went over.

I left it and came back later taking it out knowing that I would do the piston to match.

I did the piston, it was beautiful! It matched about as well as I could have wanted to on the second light pass.. I put it in and got it stuck. I realised I didnt do and finishing passes on the bore so it had a taper on it. Now the piston is well stuck and will not come out.. It is a bit damaged in trying to get it out..

I think I will go and get a 1/2" reamer.. I have a mind to do a few more engines and elmers factory engine uses a 1/2" piston as well so it won't be a one off..

Tomorrow, saturday here I will do it all again! With care and patience I should have had in the first place

Jason

 

[Twmaster]

Jason, welcome to the wonderful world of Duh! I have a box. It's full of stuff I bolloxed while machining. I call that the 'box of misfit parts'. Now and then I find a use for a misfit or three....
:big:

 

[rake60]

I can only laugh at myself now! I am trying to get through this too quickly and am screwing things up as I go, basic mistakes..

I hate being forced to say this Jason.
Regardless of what any high school guidance counselor or therapist may have told you in the past,
YOU ARE PERFECTLY NORMAL!

Slow down a bit and it will all come together.

Rick

 

[vedoula]

I did the piston, it was beautiful! It matched about as well as I could have wanted to on the second light pass.. I put it in and got it stuck. I realised I didnt do and finishing passes on the bore so it had a taper on it. Now the piston is well stuck and will not come out.. It is a bit damaged in trying to get it out..

what materials are the piston and the cylinder made of? If they are not the same material, differential expansion at different temperatures is your friend. Think heating (oven/boil) or freezing...

vedoula

 

[metalnwood]

Thanks guys, thats it - just take my time a bit more. The day only got worse though.

The kids and I hopped in the car to pick up my wife, we were driving along in slow close traffic when my son started to cry and kept on crying. His toy dog had fallen on the ground.. I bent around, picked it up and handed it back. I turned back to the traffic (eyes off the road for a second) and in to the back of the car in front! Boy was I feeling sorry for myself. Lucky it was very minor with only a bent licence plate on mine and who knows what happened to the other car as it was a panelbeaters spare that had already taken a few hits on the back..

Anyway, I now have a new blank cylinder stick ready for drilling and reaming tomorrow.

I normally dont work on small stuff like this so I spend a lot of time getting it to size. The only steel I had was a bit over 1" for the piston so I will have to take all that off again as well.

I am glad my lathe is 16" 7.5hp otherwise I could really be spending time on it..

I have listed some stuff on our local ebay like site. I expect I will be able to get some nice materials for the next build..

JAson

 

[metalnwood]

OK, back on track, forgotten all the errors so far

I have redone the cylinder, using a reamer this to finish this time. No problems here. I was going to do the piston next but I already started to do the fly wheel so I will have to finish that first.

Here are the pieces so far..

 

[metalnwood]

I can see that I may need to purchase a little more tooling to do some of these jobs.

My lathe tools are to large to work on the little wheel : So instead of turning out the inside of the wheel I moved it on to the mill and the dividing head. The dividing head is good but it takes up a lot of vertical space when it's turned this way around and has the chuck on it. Another thing to get, a chuck for my rotary table... The list is endless

First I went around the outside diameter with a 12mm ballnose taking it to the correct depth. I then rough milled in to the center and finished the inside diameter. Being a ballnose it wont give me a flat surface, I am not a human cnc ;D

I then put in a slot drill and tried to blend the surfaces which came out ok. Put it back on the lathe to run some wet and dry over it and I think it looks ok. That frees up the lathe for the piston now..

 

[zeeprogrammer]

That came out pretty good metalnwood.
I'm going to have to experiment with that idea myself.

 

[Russel]

Wow, nice flywheel!

zeeprogrammer isn't the only one that will be trying ball end mills on flywheels.

Russ