First mini lathe project, oscillating steam engine.

[Ross]

Today I drilled and tapped all the remaining holes on the crank to M3 and drilled the centre to 6mm. 






I'll get on with the piston hopefully tomorrow. 

[doubleboost]

Hi
Ross
Coming along very nicely
John

[Stilldrillin]

Your collection of parts is gowing nicely Ross! 

Good luck with the piston. Take your time. Rather too tight, than too loose...... 

David D

[Ross]

Today I got around to machining the piston.


I forgot to take the camera down to the shed for this part!


I started off at one end and brought it down to the size of the bore. But I went undersized! Luckily I just flipped the workpiece over and did this same, but this times was careful to get a snug fit inside the bore.


Once I had got the piston head made I turned the Conrod down to size and drilled a hole at the bottom so it fits the crank.


Some photos of the piston:




And the fit into the bore.




I also buffed up the cylinder it's all shiny now.




After that I scavenged an m6 bolt. It was one of those that were only part threaded, and it would be perfect for my crankshaft. [/b][/size][/font]


I sawed the thread to size, then put it in the lathe and face it to length.





I was expecting to do a small cut to the diameter of the bolt, but I tested it with the crank first and it fit snugly so I've left it!




That's it for this weekend,

[doubleboost]

Hi
Ross
It wont be long before it is a runner
John

[Ross]

Today a little brass rod I ordered arrived, 

It was for the trunion bolt, (I might get some hex for that) and the crank pin. 

I started on the crank pin and I would've got it finished, but the god old tap and die set let me down once again. Before I threw it all half way across the UK I stopped, and put the small useless tools in the bin where they belong! I had some success with using the bigger sizes of that set, M8 and M6 etc.. But the smaller ones are not machined properly, if at all. 

Anyway... Onto the crank pin. 

I started by facing the brass then turning the diameter to 3.5 mm. From there I worked my Down with small cuts until the hole in the Conrod of the piston was a good fit, not sloppy but enough play so it just "dangles"

Facing:




Testing with the piston:




I then proceeded to take part of the pin down to 3mm so it can be threaded with the die. 



I got the die out and it wouldn't start on the pin. The exact problem I was hiving with the taps, I applied a bit more pressure while turning.  And then the die just slipped off the end leaving a nice trail of marks behind it. 




Being the perfectionist that I am,  tided up the end and extended the 3mm diameter a little bit. I'll get a 3mm die from a good tool shop next to my college and thread it on Thursday. 

[DaveH]

Hi Ross,

Coming along nicely

Sometimes it helps to put a small chamfer on the part you are going to die.

Also many dies have a "right side" to start the thread

Looking good Ross
 
DaveH

[andyf]

Looking good, Ross 

Like DaveH says, a chamfer can help the die to get started. And the side of the die which should be facing the work is usually the side with the size etc etched on.

If it's a split die, open it up a bit with the conical middle screw in your die stock or die holder before you do up the screws on either side.

Another way to get it going is to put a bit of M3 rod in your tailstock drill chuck, run the die on to it, butt the M3 rod up against your embryo screw, and run the die across the join with a diestock until it has cut a turn or two with the M3 thread pushing it forward. If you have no tailstock die holder just carry on with the die stock, but if you have a tailstock die holder change over to it, because it will be better at keeping the die aligned.

Andy

Andy 

[saw]

Remember Ross the diameter must be 2.94 mm for a 3mm die 

[Ross]

I had a go at threading the brass pin last night but I failed, so I gave up. I re made the pin tonight in bras again and it just wouldn't work for me, the threads just seemed to be crushed. I turned the diameter to 3.00mm and by the time the die had done its work it was a mess and down to 2.60mm. 

I decided that maybe the brass was too soft for this size of die, so I tired aluminium instead. 
I remade the pin once again, and it threaded beautifully. 



I parted the pin from the Ali rod and faced up to length its now attached to the crank:



I had to make adjustments the piston as it did not have enough clearance for a full turn of the crank so a few mm was taken off. 

I want to try and Sort the base out this weekend.  Do you guys think it would good chamfered or a few steps added to it for decoration?

[saw]

I turned the diameter to 3.00mm
As I told you you have to turn the diameter to 2.94 mm otherwise it will fail. 

[Dean W]

Some steps on the base would dress it up nice, Ross.  Then break the edges just a bit.  Up to you, of course!
Far as threading goes, if you have a good split die, you can thread it full diameter with no problem.
Looks like you did fine with the aluminum one.  A chamfer helps with what ever type die you use.

[DaveH]

Ross,

A couple of steps and round the edges off can look nice. Takes a bit of carefull doing.

"Beauty is in the eye of the beholder"

 
DaveH

[Ross]

I turned the diameter to 3.00mm
As I told you you have to turn the diameter to 2.94 mm otherwise it will fail. 

Surely 0.06mm would make too much of a difference?

Some steps on the base would dress it up nice, Ross.  Then break the edges just a bit.  Up to you, of course!

I think steps would be good, what do you mean by breaking up the edges? with chamfers?

[DaveH]

Ross,

"Breaking the edges" just a term used to say no sharp edges. Can be done carefully with some fine emery in the lathe. Just enough to take off any sharp edges. Makes it "nicer" to handle.

Chamfer is normally a more specific operation to a achieve a desired look, or to get rid of what was a bad edge.  A chamfer may be 1mm, 3mm or more, remember now you have two extra edges to break, either side of the chamfer.
 
DaveH

[Stilldrillin]

I turned the diameter to 3.00mm
As I told you you have to turn the diameter to 2.94 mm otherwise it will fail. 

Surely 0.06mm would make too much of a difference?

Frankly, I don't think two thou', will make any difference at all....... 

You're doing well, Ross! 

David D

[Bluechip]

I have some 3mm stainless round which mikes up as 3.09mm. Why, I don't know. But as 3.09mm is some .0035" less than 1/8" I would guess it's actually 1/8".

Bought together with some 4mm & 5mm which are correct. Seen off AGAIN ... 

Anyway, I can get a 3mm thread on that OK.

Sure you have brass, Ross ?? Not something awful like drawn Phosphor Bronze ??

Die opened out properly, some need to be all the way out. ??

I would suggest if it will do ally, it should do CZ121 brass .. aluminium is mostly rubbish stuff to thread, depending on the grade.

BC

EDIT Try putting a taper lead to start the thread .. like a long chamfer ...



 

[Dean W]

I have some 3mm stainless round which mikes up as 3.09mm. Why, I don't know. But as 3.09mm is some .0035" less than 1/8" I would guess it's actually 1/8".

3.09mm is .0035" too big for 3mm and .0035" too small for 1/8".  You got the shaft both ways.  ; )

[Ross]

Didn't get as much done as I'd hoped this weekend. 

I Finnish turned all sides on the base and put a chamfer on the top. I'll see how it looks once it is assembled it may look better with steps. 



As or the threading on the brass I'll give it another go when I do the trunion pin M4.

[Ross]

Hi everyone

Just took a break form this project and I'm getting back into the swing of it now. 

Today I made the trunion bolt. 

first I turned the end down to roughly 4mm for the M4 thread. The depth of the hole on the cylinder was 6mm. 

I then threaded the diameter and turned the rest of the bolt to 5mm




I drilled the 5mm hole in the plate that will hold it all together. 

 

I parted off the bolt and faced the head to a sensible length and our a slight chamfer on the top. 



The finished product:





I'll try and make the brass parts for the portholes tommorow. 

[Stilldrillin]

That looks good Ross! 

Nice to see you're back on the job........ 

David D

[krv3000]

well dun can not wate to see it all made up

[doubleboost]

Hi
Ross
Pleased to see you back on the job
Looking good
John

[Dean W]

Good job on the bolt, Ross.  Looks very nice.   

[Ross]

Today I made the brass nuts that that the steam and exhaust pipes will be soldered to. 

First I turned 20mm of the brass down to 3.90 mm I was determined to have another go at threading the brass. 




The I cut the metal and turned it around in the chuck and faced it to length. 



I drilled a 2mm hole right through the piece. This will be the port hole essentially. And I took the outer diameter down to 6mm. 




I turned the piece back around and threaded m4 with the die. 



I repeated these steps and made another. 




I drilled and tapped the main plate and screwed them in. I will seal the threads with Plumbers PTFE tape and a fibre washer, that should stop the steam.