Re: My second engine - the ez2 (running)

[njl]

Hi Folks

Well it feels an awful long while since I built my first engine here back in the spring. My "living list" of tasks that needed doing around the place has kept me out of the shop for way too long. So now I'm grabbing some much needed shop time and have made a start on my next engine project which is my take on Black85vette's ez2 engine, an engineering refinement on the MaCabe's runner. I'm hoping to build on my ez engine build experience and learn some more good stuff as I progress along with this build and if it's of interest, your very welcome to pull up a chair and join me on my voyage of learning.

My first step was to cut the metal for the frame. I'm using a piece of 3 inch wide steel for the base and the remnants of the 3/4 bar steel stock as used on the ez engine build. I just about had enough left on the bar for the job. Despite my best efforts to minimise waste material by cutting straight I was just a tad short on the last piece but a slight modification to the bell crank pivot assembly should see me through.

Here is the sawn stock laid out roughly in position on the base. In the background you can see my newly crafted pump centre. This should help me in setting up work in the 4-jaw chuck. It was the first time I've cut anything on a taper and it was quite satisfying watching the point come together. I've not put a spring-loaded tail stock end on it yet, (as I didn't have a suitable spring to hand) rather just a centre hole but I can add this later if I need it. My thinking is that if I get the part set up reasonable close by eye first off I shouldn't need it.


Next it was off to the Bridgeport to true up those rough sawn edges. I'd previously spent some time getting the tram right on the mill and was very pleased to make nice square blocks as a result, definitely worth the effort. At some point I'm going to make a duel dial gauge traming tool, a la John Bogstandard's thread on another forum.

Well that's it for this episode.

Nick

 

[Deanofid]

It looks like you're off to a good start, Nick.
That pump center will come in handy.

Dean

 

[njl]

Thanks for looking in Dean, your absolutely spot on the pump centre is simply a brilliant tool. So simple yet so effective. On the ez engine build I really struggled for ages to get the cylinder block set up in the 4 jaw ready for boring. Marv suggest that next time I try a pump centre and an elephant foot for the dial gauge. Well blow me down with a feather this time it was so easy to dial in the 4 jaw, it literally took me seconds to get it trued up. At this rate I might even become a fan of the 4 jaw!

Here is a quick snap of how I set it up. To anyone new like me looking in, if you've never tried one give it a bash and I think you will be amazed at how simple it is to get things set up.

I didn't have a small drill long enough to make a 2 inch deep hole through the stock so I will need to turn the stock around to complete the inlet port at the back of the cylinder. After making a 3mm hole as deep as I could, I opened up the front part of the bore to 10 mm, my biggest drill and then bored it out to size. This time I decided to be brave and use the auto feed to make the cut, it gave me a better finish than I could manage on my ez build making the cut by hand.

This shot is the finished cylinder bore, the tool shows the very fine swarf generated by the 3rd spring pass (I cleaned it off after each pass).



Now the cylinder bore is done I hope I can just loosen two jaws turn the stock round in the chuck, retighten the same two jaws and drill the inlet from the back with a reasonable chance that the inlet hole will meet up.

Well that will be tomorrows experiment, but I reckon it should work OK. The join may even end up in the area of metal removed by the valve hole.

Nick

 

[mklotz]

Marv suggest that next time I try a pump centre and an elephant foot for the dial gauge. Well blow me down with a feather this time it was so easy to dial in the 4 jaw, it literally took me seconds to get it trued up. At this rate I might even become a fan of the 4 jaw!

Did you make a clone of your chuck jaw wrench so you can manipulate the 3 and 9 o'clock jaws without wrench juggling? Not a necessity but it makes things go even faster.

 

[njl]

Thanks Marv, I saw you give that excellent tip somewhere before, maybe on your website?. It's something I took on board and I'm definitely going to do very soon.

My 4 jaw chuck takes a 12mm hex key. I know I could just buy another one but for practise I'm going to make one in the mill using a bolt screwed into the stock to act as a six sided index reference (I have no dividing head or rotary table yet).

I'm still really blown away by how much simpler the pump centre made the 4 jaw set up task. It beat all my expectation's by miles, its a huge leap forward for me. Thank you again for pointing me in the right direction.

Nick

 

[mklotz]

That should work. Or maybe you have a piece of hex stock larger than 12mm. Carve the wrench nose from that using the existing hex faces as reference.

When you go to make a handle for the new wrench, check the clearances you have on the back side of the chuck. I had to make mine a bit shorter so I could use it in that position.

 

[black85vette]

Looks like you are off to a good start. See if you can improve on the design even more. It would be cool to see an evolution of this design with each build adding something to it.

 

[arnoldb]

Hi Nick

Glad to see you're back at it; and very happy to hear you're getting along with the 4-jaw Thm: It grows on one, and once you're used to it, it is an indispensable accessory.

Good luck with the rest of your build Thm:

Regard, Arnold

 

[njl]

Thanks for dropping in BV. I was thinking along similar lines. In building the ez2 I want to do any machining jobs similar to those I used on the ez better, with more accurately and precision and I also want to try some new things too, to extend my knowledge. I'm going to add a couple of bushes to each end of the central shaft's mounting block. That's why I have drilled a bigger hole. I'm also thinking of doing the conrod to piston connection differently so I get to a bit more machining practise. I don’t feel the need for speed of construction so badly, I'm sure I can get a runner and I want to make a better job of it.

Thanks Arnold, loved your rotary table build BTW, yes I'm getting to like using the 4 jaw.

Here are a couple of pics of the current state of play.

The cylinder block is done and fitted to it's support block. Turning the cylinder block around to complete drilling the port from the other side worked OK. I was a bit worried that it might not meet up squarely or that it might break the 3mm drill as it broke through (I've done that before) but all worked fine.

All the blocks are now tapped for fixing to the base plate. The bell crank's block is not fixed to the plate yet. I'll not do that until I've got the valve and flywheel constructed. I still marked out the holes and gently centre popped them but this time in stead of using my eye I used the dials on the milling machine to position the holes. So far all the screw together parts fit together with out any fetling. (3mm bolts in 3mm holes.)

What a difference in finish between the bored hole on the left and the drilled hole on the right.

Well thats it for this update. Next I'm going to start making some parts on the lathe.

Nick

 

[njl]

Thanks for the heads up Marv, I'll make sure that the tool will fit the gap. I've got quite a bit of space back to the splashguard so it shouldn't be a problem. I have a tiny 4 jaw I bought a while back to hold some small square stock for a job I was doing making some more bolts for my dixon tool post. (A chuck in a chuck idea.) It uses a small hex key of which I have several so I had a play with the two key method, yep it works an absolute dream so I'll get one knocked up for the big chuck ASAP.

Nick

 

[njl]

Well, got a bit more done today, made the piston, a couple of brass bushes for the main shaft and the valve.

I'm quite pleased with the piston and the bushes but the tab on the valve went a bit wonky, I tried to re-cut the tab a few times on the mill but only managed to make matters worse. I think I'm going to have to resort to the file to sort it out. It's useable as is but not quite how I wanted it. It does fit the cylinder block fine so that's something!

Well it's been a busy old day here today had to deal with two wasp nests, one in the house roof and one in the holiday cottage roof, that's the second I have removed for there this year. The cold winter has been very good for the wasps as they didn't break hibernation early (which usually does for some of them). They are also becoming a major pain robbing my bees too!

Nick

 

[Deanofid]

Things are looking good from here, Nick. You're starting to get a collection of parts. Pretty soon,
they'll be another engine!

You have it just right when you say 'with more accuracy and precision'. That's the way to get
good at this stuff. Make a little improvement in your skill each time you build something, and
before too long, things that looked impossible in the past will start coming to you as doable.

You're going along great. Keep it up!
Thanks for the updates.

Dean

 

[njl]

Thanks Dean, yep I feel it's moving along nicely so far and I am learning and improving. Here are a couple more parts. The axle is cut down from a piece of 6.3mm silver steel stock to fit in a 5.5mm hole. Once again I struggled a bit with the spring whilst making this part. This time I took a slightly different tack. I roughed down a 2 inch section and then cut it off from the bar re-chucked it and then made an end fit, turned it around in the chuck and made the rest of it fit, so as to minimise the over hang. I also stepped up the speed on the lathe to 1300 odd RPM, reduced the feed speed to minimum, used lots of lube and took several spring passes. Got better results than on my previous ez engine shaft. But I think I will soon be making a travelling steady for the lathe to help with sort of job in the future. Working on short lengths I can't use the tail stock to support it as it would foul on the tool post. Alternatively I could see if I could source stock of the right size but I feel this is cheating.

Here is a shot of my first tap break. It happened whilst I was making the thread to secure the wheel to the shaft. Fortunately the tap broke outside of the part and so I could just wind out the broken end with a pair of pliers. It just sort of peeled apart as I took a cut, there was no warning or binding, it appeared to be working fine and then snap. It was a 3mm tap and had made 20 plus thread prior to breaking. Looks like a stress fracture maybe?

Here is a shot of the shaft and wheel in situ. The shaft will be cut down once the flywheel is made. The middle of the shaft in between the bushes is in free air so any blemishes in that section where the two cuts meet have no effect on the engine turning.

Next off, I'm making the connecting rod. Got a few ideas for this one, I'll share the results next time.

Nick

 

[Deanofid]

More good progress, Nick.
Taps do break. Usually from starting them off center or at an angle in a hole,
or from taking a little side pressure from the guy turning it. If you use one of many
different types of guides, your tap breakage will go way down.

Thanks for the new post!

Dean

 

[arnoldb]

Good going Nick - besides the broken tap!

I fully agree with Dean re the broken tap and the causes ;D
Don't chuck away the tap though; grind the tip flat and you have a short (from what I can estimate about 4mm long) but effective bottoming tap left - or check the shank size; there's a D-bit reamer hiding in there

Alternatively I could see if I could source stock of the right size but I feel this is cheating.

Nope - I disagree; its not cheating ;D - rather, it is a good idea for learning. Most of the plans I've seen were drawn up around available stock of the right size, and I for one am not hesitant to adapt dimensions to use what is available. It's very satisfying to turn over-size stock down to the precise diameters needed, and there lies the learning exercise. Once mastered, and you can do it if you have to, it sort of becomes irrelevant for run-of-the-mill machining. For things like silver steel shafts, you are already paying good money for getting a finished product in the first place - so why not use it if you could have turned it in the first place? Rather spend your shop time on getting better finishes on the pieces you have to machine down all the way

Kind regards, Arnold

 

[cidrontmg]

Nope - I disagree; its not cheating ;D - rather, it is a good idea for learning. Most of the plans I've seen were drawn up around available stock of the right size, and I for one am not hesitant to adapt dimensions to use what is available. It's very satisfying to turn over-size stock down to the precise diameters needed, and there lies the learning exercise. Once mastered, and you can do it if you have to, it sort of becomes irrelevant for run-of-the-mill machining. For things like silver steel shafts, you are already paying good money for getting a finished product in the first place - so why not use it if you could have turned it in the first place? Rather spend your shop time on getting better finishes on the pieces you have to machine down all the way

Kind regards, Arnold

Amen to that, I fully agree. Even though I´m retired (yesterday, and again today...), my most valuable asset still is shop time. No point in wasting it to something that´s already been done plenty good enough. Especially to something I´ve done so many times that I know for certain I can do it, if need be.

 

[Maryak]

Nick,

Looking good. :bow:

Some good advice about the broken tap re-use. Usually when I break one, I lose my cool and give the remains a buoyancy test. : Hate to think how many potential D bits I've heaved.

Best Regards
Bob

 

[bearcar1]

x2 what Arnold and Dean said. The #1 cause of tap breakage is the application of too much side force closely followed by the user not clearing the chips regularly enough combined with and/or dull taps. The usage of shafting that is readily available is not cheating. Personally I would rather use already made shafting if it is of good quality. Your EZ is shaping up quite niely.

BC1
Jim

 

[ksouers]

The parts are looking great, Nick. I guess it'll be running soon!

Ditto what everyone said about using materials already at the right size. It frees up more time to sweat over the little fiddly stuff.

 

[njl]

Sorry I've been away for a while, we've had folks staying in our holiday unit above my workshop so I've not been able to do any work for a while.

Thanks for the tips and comments on the tapping, now I know I didn't just break a tap but rather I made myself an opportunity for a new tool.

Also once I've master the machining of thin rods I'll join you all in using bought stock as is, I appreciate your comments and they do make perfect sense but right now I'm finding small axles hard to do well and so I definitely still need the practise. At present just making anything on the machines is exciting to me. Next time I buy more rod I'll make sure that I have a drill size to match so I can use it straight if I want too. Currently my 0.1 mm step set of drills stops at 6.00 mill so for 6.3mm rod I have no option but to reduce it a bit.

Right oh then, on with the build.

Here is a pic of the setup I use for holding small parts on my lathe. I cut a thread with the lathe on a length of steel rod to mount this small chuck, it's a 14mm 0.1 pitch thread. I have also drilled out the inside of the rod so that I can hold longer items than just the depth of the jaws with the chuck. The jaws are holding my connecting rod.

We're getting a bit closer, here is a pic of the connecting rod and the flywheel mounted on the engine. I'm not entirely happy with these two parts yet. I've still got some clean up to do and will try and do better next time. The flywheel spins over nicely by hand and the piston glides in out of the bore OK. Operating the valve at the rear of the cylinder has an affect on the resistance to motion so things are looking good for a runner.

This final shot gives an idea of what I have left to do. I need to make some linkages to get drive from the flywheel to operate the brass valve at the top right of the picture. Sorry it’s a bit dark.

Valve linkages next time then and then we can see if this baby runs.

Nick