A Beginner's First Engine (Single-acting Oscillator)

[b.lindsey]

Gary, that is an interesting vise you are using on the mill. Any information on it? Manufacturer, etc? The cylinder looks good too!!

Bill

[gary.a.ayres]

Hi Bill -

I don't know the make of the vice and it doesn't seem to have any manufacturer's markings on it (though I will check the underside of the base when I take it off the mill). It's almost certainly British and of a fair age. It came with my Dore Westbury milling machine http://www.lathes.co.uk/dore-westbury/ and that mill was made in the late 1960's or possibly early 70's. The vice probably isn't bespoke to the DW though. My DW is currently at my place in France, awaiting a bearing change and a new motor. The vice is really good - well-made and accurate, as things were in those days.

Thank you re the cylinder.

gary

[Gas_mantle]

Taking shape nicely Gary, a bit of drilling and making the piston/conrod then you are nearly there.

What is your intention with the piston? I know most small oscillators don't have rings but I found a shallow groove to accommodate a bit of graphite yarn helps. Even if it doesn't work you'll have an oil groove that won't do any harm.

Soon be time to get your boiler earning its living 

[gary.a.ayres]

Yep, getting there Peter, and another post to follow this one.

My aim is to make the piston and con rod in one piece. I hadn't given the graphite yarn / groove question any thought, but it sounds like a good idea - thanks.

 

[gary.a.ayres]

I have a box full of stainless steel M2 cap head screws complete with taps and tapping and clearance drills which I had built up for a currently sidelined project, These came in very handy today. In order to drill the three clearance holes in the cylinder cap for the fixing screws, I used my cheapo Dremel clone on its stand with a small rotary table fitted with a 4-jaw self-centring chuck and a dividing plate:





The drilled cap was then used as a template for drilling the holes in the cylinder. I followed the usual common-sensical procedure  of drilling and tapping one hole first and fixing the cap before drilling the other two. I did the tapping on the mill using a piloted spindle tap wrench. Taking no chances with these small taps! 



The result:





I then turned the main bearing from some round bronze bar, leaving the flange some 5mm wider than in Steve's plans to make a bit more of a feature of it given that my standard is wider than the original. Again, the clearance holes were drilled on the Dremel clone dividing setup:





Quite a satisfying day's work. I'm getting hooked on this...

[crueby]

Yup, you are hooked! Welcome to the club!!   

[gary.a.ayres]

Cheers Chris. Pleased to be a member.   

[Kim]

Looking great, Gary!  You're making good progress 
Kim

[gary.a.ayres]

Thanks Kim.

 

[b.lindsey]

The cylinder cap holes look good. Just curious, why use the Dremel for the cap holes rather than the mill?

Bill

[gary.a.ayres]

Good question.

I have found that some standard drill chucks don't hold very small bits very well, while the Dremel type tool uses small collets specific to bit sizes.

In fairness, though, I haven't tried the drill chuck that came with the mill on such a small size, so it may actually be fine. However, I knew the Dremel would work, so I used it.

Just habit really. 

gary

[gary.a.ayres]

The silver steel arrived today - 6mm for the main shaft and 3mm for the crankpin.

I tried the flywheel on it and found that it still made a loose, rattly fit. I'm not sure why this was the case, but there it was. Strange, because the bronze main bearing - which was drilled and reamed with the same tools - was at first reluctant to even go on the same shaft.  I was initially dismayed, but this gave way to the idea of drilling out the central hole of the flywheel and bushing it. This may be a blessing in disguise, I thought, because the bush could also be extended as a boss on one side of the wheel which could be cross-drilled and tapped for a grub screw - something which I had fancied from the start but for which there was previously no room for on the hub of the wheel.

So... I drilled and reamed the flywheel to 12mm:



I then turned a bush from brass which was drilled and reamed to 6mm. This is a stepped part with a narrow section of just under 12mm which goes through the new bore of the wheel. I followed Ramon's advice on page 5 of this thread for using abrasives to creep up on a diameter, and it worked a treat on the bush. The wider section of the part is of a similar diameter to the existing hub of the wheel, and this was cross-drilled and tapped M4:



 For the cross-drilling I used my new DRO for the very first time, in conjunction with an edge finder to locate the centre of the boss. So far I have only installed the DRO on the Y axis (waiting for material to arrive to make a mounting bracket for the X), but one axis was all  that was needed for this. It gave me a sense of what a fabulous thing a DRO is...

The part was then glued into the flywheel with Loctite. Well, not Loctite... 'Interseals R41 Bearing Fit', which Interseals tell me is just as good as Loctite but less expensive. Well, we shall see:



The photo below gives a sense of the part in situ in the flywheel. The long section at the 'back' of the wheel can easily be reduced or turned off later. The boss is also possibly a bit on the long side so it can also be reduced a bit if it will improve the look:



Finally, here are the flywheel and the main bearing temporarily mounted on the 6mm silver steel, just for show. They both now make a lovely sliding fit with no lateral play:



If the grub screw arrangement causes any wobble problems I can always still Loctite the wheel to the shaft, but I'm hoping that won't be necessary and of course there is more work to be done using an ER-32 collet chuck in the lathe to persuade it to run true.

gary

[steamer]

Gary,  next time you try reaming a hole, slow everything way down, and feed gently and deliberately.   Once you feel it go through, STOP the lathe...like immediately.

Then back the reamer out with the spindle stopped.

I've had way better luck using reamers like that... 

Dave

[gary.a.ayres]

Dave -

I did slow the lathe down and fed slowly.

However, I didn't stop the lathe immediately and I *think* it was still running when I backed it out. Maybe that's why the hole in the flywheel was too big initally. It's sorted now, though.

Thanks for the tip!

[steamer]

Dave -

I did slow the lathe down and fed slowly.

However, I didn't stop the lathe immediately and I *think* it was still running when I backed it out. Maybe that's why the hole in the flywheel was too big initally. It's sorted now, though.

Thanks for the tip!

That's happened to me before.  What I think happens is a chip gets between the bore and the reamer on the way back out, and pushes the reamer sideways, and makes the opposite side cut in deeper.        A way to get a reamer to cut bigger, is with a cigarette paper.    Zig Zags are 0.0008" thick, if you put it on a tooth of the reamer, it will make it cut slightly bigger....but exactly how much is a little bit vague.  Depends on material.