My First Build - The EZ engine

[njl]

Hi All,

Well today I finally managed to find some shop time to make a start on my first build. I decided to give the EZ engine a go, given that it is a project aimed at the first timer I hope it is just the ticket for me.

I'm sort of used to metric and imperial measurements, but my brain visualizes sizes in imperial. My mill is imperial so I have been buying imperial cutters for it, my lathe has both on it's dials and all my drills, taps and dies are all metric. Hence I have decided that my build will have imperial dimensions except for all the holes. This may sound odd but it works for me.

So both set of plans have been down loaded. My first job was to take the imperial decimal dimesions and convert them to imperial fractions so I could measure the sizes of the parts with my ruler. I knocked up a spread sheet of all the 1/64th - 64/64th factors to decimal. My rule has up to 64ths on the scale but that is a challenge for my eyes. Maybe you guys have a way to layout in imperial decimal but I would have to use the mill table and wind the dials to do that?

Anyway here is a selection of metal stock that I am going to use. Steel for the frame, cylinder and valve case. Brass for the piston and valve and ali for the flywheel.

The first job was to cut the frame, cylinder and valve blocks from the stock

The band saw does a reasonable job but I need to clean up the cut edges in the mill and bring the parts down to size.

I'd just got the base plates set up on the mill when our holiday guests returned to our Loft House holiday apartment which is situated directly above the workshop so I had to call a halt for todays operations, so as not to inflict my machining noises on them, that wouldn't be fair.

The build will progress slowly but I hope steadily, I feel good to have finally made a start, more later.

Nick

 

[4156df]

Nick,
Thanks for taking the time to share your build with us. I'm looking forward to watching.
Dennis

 

[arnoldb]

Nick, you took one of the important steps; that is to start ;D

You will find a rule for marking out a bit inaccurate, and while it should be usable for the EZ engine, maybe you must give some thought to getting a digital caliper. I see you live in the UK; you'll find the cheap Asian imports are very affordable - and the digital readout is nice and big to read

Good luck with your project!

Kind regards, Arnold

 

[Swarf Rat]

Great start. I'm interested in watching your progress.

 

[Deanofid]

Good start, Nick! Keep us posted. Most of us are pretty interested in first builds, since we remember it well.

Have some fun. We're in your corner.

Dean

 

[trey3670]

some of us are looking to learn from your first build to start ours!

 

[njl]

Thanks for all the kind words, I'll share with you the things that I learn along the way, I've got a lot to learn and I'm already learning , Arnold has already triggered a light bulb in my head.

As it happens I do have some digital calipers but had been using them pretty much exclusively to measure the diameter of parts I make on the lathe. I've already found them very useful for that and I have also noticed that when doing inside measurements the size of the hole might be just a tad bigger than the reading as the edge of the jaws can fowl on the wall of the bush so they can't expand fully to the exact size of the hole (Bare this in mind when making interference fits.)

It never occurred to me that I could also use them when laying out measurements, it is so obvious I could kick myself! Thanks again for the tip Arnold.

Nick

 

[black85vette]

Great! Thanks for posting. Be sure you have the plans with the upload dated in November as the older upload had a couple of dimensions wrong on the upright of the frame.

Does not hurt to layout and visually confirm that all holes line up with the other parts BEFORE drilling. ;D Saves some agravation and scrap creation.

There have been about 5 or 6 of these posted on the board so there are plenty of pictures and posts about them. Still feel free to ask questions if something is not clear.

Have fun!

 

[mklotz]

...I have also noticed that when doing inside measurements the size of the hole might be just a tad bigger than the reading...

Examine the inside jaws of your calipers closely. They probably have a tiny flat on the measuring surface. This means that they are actually measuring the distance between two chords of the hole, a distance that will always be less than the actual diameter of the hole.

In general, calipers are not useful for precision measurement of holes. Use expanding ball gauges or telescoping gauges.

 

[njl]

Black85vette - Thanks for the heads up on the plans version. I think I have the right set but will double check before drilling. I have seen the other EZ threads too so have some idea of what I should end up with!

Yep Marv your spot on, that is exactly what happens with my calipers.

Well I made a bit more progress on the build today. The first step was to clean up the parts I cut yesterday.

This is how the parts ended up after I milled them.

All went to plan without any drama and I am pleased with the result but for anyone about to start using the mill for the first time here are a few things I learnt when I milled my first job (smoked my first cutter) making Tee nuts to hold my vice to the table.

1) Make sure the tool is turning the right way. On my machine the back gear reverses the direction of rotation so you need to switch the motor direction depending on the high/low speeds.
2) Make sure it is not going too fast I found out that turns the cutter straw and then blue.
3) Lock the axis which is not supposed to be moving.
4) Don't try and plunge end mills.

Meanwhile back at the build it was time to mark out where the holes are going to be drilled. For this step I used blue layout fluid. I'd never tried it before but it worked a treat. Just put a few drops on the part and wipe it over with a paper towel to spread it out.

Thanks to Arnold's tip I then used my calipers to scribe the lines. I worked a treat.
Here is a pic of the frame marked up.

It looks better in real life than on the photo. It is very easy to make a scratch marks and hardly needs any pressure on the caliper jaws.

Next I used an automatic center punch to pop the hole positions. I found that getting the pop spot on was more difficult than I expected. Here is the result

I'm not entirely happy with this its very close but not perfect. Close enough I think but as the school report used to say needs to try harder next time!

Unfortunately my shop time was up and I had to get back to the gardening, the only consolations are; it was a smashing day here weatherwise and I get a chance to double check that the plans are correct before I make any holes.

Tomorrow I'm RC flying all day so doubt I'll get any more done until later in the week.

Nick

 

[arnoldb]

Good progress Nick

And thank you for the mention; I'm happy if I can help someone.

Kind regards, Arnold

 

[njl]

Marv,

I just had some more thought about using my calipers for the hole size measuring. As I don't have any ball gauges yet I reckon this formula might work.

If I take 2*(square root ( (0.5*cord) ^ 2) + (0.5*caliper reading) ^2 )) I should get the diameter of the hole.

Where the cord = the caliper jaw width.

In practise it might be a bit of a kludge but it should get me closer than my current "the reading + a tad" method!


Nick

 

[mklotz]

Nick,

Your formula is mathematically correct but I don't believe that you can determine the "chord" value accurately enough to get good results. Furthermore, what you're suggesting relies on getting the calipers exactly on a diameter - something that's not easy to do.

Calipers are not the appropriate tools to measure hole diameters accurately. The generally accepted techniques go something like this...

diameter <= 0.25"
pin gages

diameter 0.25 - 1"
pin gages
ball/telescoping gages
inside micrometer

diameter > 1"
telescoping gage
inside micrometer

There is some overlap, of course, but that's a good guideline.

One can spend a lot of money buying tools to measure holes. For someone starting out, I would recommend that you buy some ball and telescoping gages first, then graduate later to an inexpensive import inside micrometer.

Edit...

One can make surprisingly accurate measurements of a bore with nothing more than a stick with rounded ends and a micrometer. Download RATTLE.ZIP from my page and read how the old-timers did it. It's a useful technique to add to your arsenal.

 

[njl]

Thanks for the advice Marv. I've added Ball + Telescopic gauges to the tools wish list!

Most of the critical holes I have made up till now lie in .5" - 1.5" range. As soon as folks learn you have some machine tools, little repair jobs come your way. I had a nice job to do a while back on a Westwood lawnmower where the belt to the grass sweeper had to turn through 90 degrees to feed the drive from the middle of the machine to the axel of the sweeper brush. The part was basically a shaft with two pulleys sided by side but it was also an adjustable tensioner for the belt, allowing the axel to slid in and out on three bolts, one in each end of the axel and one long bolt right through the middle of the shaft, like a tee shape. The old part had warn very badly, one of the phosphor bronze bush had completely gone and made a right old mess of the pulley and the axel. I opened up the hole in the pulley to get a nice clean parallel hole and then made up a new thicker phosphor bronze bush which I managed to shrunk fit into the blow lamp heated pulley. Swmbo still doesn't know that I had this lump of metal sitting under the frozen peas in the freezer! (but I did put it in a plastic bag!) I then made up a new axel assemble to hold both the pulleys and provide the tension adjustment and the mower was as good as new. Doing that job was how I found out first hand that my calipers were not good for measuring the hole diameter.

Anyway glad my maths was OK. I was driving out to our flying field this morning and my brain was buzzing with, "if you know the cord length and the distance between them you should be able to work it out".

Nick

 

[Deanofid]

You're doing well, Nick. I think things are looking just dandy.

4) Don't try and plunge end mills.

You can, with the proper end mill. Don't know your country, and they're called different things in different places. In the U.S., center cutting end mills are made for plunge cutting. I think it's called a slot drill in G.B. Elsewhere, ask a local machinist, or look at the end of the mill. If it's meant to plunge, at least two of the edges on the end will meet in the middle of the diameter of the tool.

Keep it up. Hope you had a good flying day.

Dean

 

[njl]

Thanks Deanofid, must be a terminology thing.

Yep over here (in the UK) we seem to have end mills which don't plunge and slot drills which do. Typically size for size, end mills have more flutes and give a better finish, well in my (very) limited experience that's what I have found to be the case anyway. (I've only got a handful of cutters)

Yep flying was great, it's a Sunday ritual for me. I must get my flying fix or I get bad withdrawl. Hope to get some more done on the build today, metal working is becoming very addictive too. Will post back later with some more build progress.

Nick

 

[njl]

Right oh, here is a bit more progress from today. I manged to pop into the workshop for five mins and blow me down 2.5 hours later I had made the frame.

Glad to say I had the latest version of the plans and all the holes measurements were fine.

First off I moved a couple of pop marks slightly, re-punching at an angle towards where I wanted them to go. This worked very well, I was quite surprised that it did. Then it was time to drill them. I do have a drill press but decided to use my mill to do the work as it has a vice and I can use the dials to move the drill to the precise spot I want to drill.

Here is a snap of the main face of the frame just about finished.

Next job was to tap the M3 holes. I have seen lots of different ideas on how to make sure the tap runs straight, this is how I do it.

The chuck is just resting over the end of the tap handle and serves as a support and guide.

All holes tapped OK but I did have a spot of drama with the cutting fluid. I had a new bottle which was very full. I was just dipping the tap into the neck of the bottle each time I started a new hole on the last hole the tap fell out of the tap handle and into the bottle. So now I had to get it out, well I put the cap back on the bottle, turned it upside down, held the magnetic base of my dial indicator on the cap, turned the bottle upright again and carefully unscrewed the cap and hey presto it was dangling from the cap oiled up and ready to use! My tap handle has quite a coarse thread and it is very easy to twist it slightly when holding small taps.

Here is a shot of the tapped holes.

Once I'd completed the other faces it was moment of truth time. Would the base fit on the frame or would I have to open up the holes and make some wiggle room. Well much to my surprise it fitted without any further adjustment.

So here is a pic of the finished frame.

The screws are just some I had to hand to show the fit and are too long to screw fully home. I've not decided yet if I'm going to use countersunk heads or maybe add some decorative feet and go with cap head bolts. I use these cap head type bolts a lot for model planes.

Well that's all for today. Next I'll start on the cylinder block. I'm thinking I will use the 4 jaw chuck for this in the lathe. It will be the first time that I have used it in an offset (non centered) type mode. I don't have any reamers so my thinking here is drill to near size and then use the boring bar to get a nice round hole. Does that sound like a good plan?

I've already had a play with the four jaw armed with Marv's set up guide when I made some extra 1/4 inch square top bolts for my lathe's Dixon tool post. Thanks Marv, I found it very useful.

Nick

 

[Deanofid]

Hi Nick;

I don't have any reamers so my thinking here is drill to near size and then use the boring bar to get a nice round hole. Does that sound like a good plan?

Yep, that's a good plan. It's how many of us do it if a suitable reamer isn't available. Just take the last few cuts very light, meaning about .001" when you get down to the last few thou to meet your diameter requirement, and then try a couple of passes without putting on any more cut. It'll clean up a bit even without adjusting more on for a cut, and will make a nice straight bore.

Then make the piston to fit the bore.

You're on your way. The frame looks good!

Dean

 

[njl]

Thanks Marv for pointing me to the rattle.zip archive. I down loaded it and had a read of the text. I think I get the gist of what your trying to do but I have a couple of question which I'm not sure about. Firstly when you put the stick across the bore how do you ensure it is a right angles to the bore. Secondly once you have narrowed the space to just the rattle room. How do you measure it. IE. how to do you measure the size of the rattle?

Thanks Dean for your info on making the cylinder, glad I'm on the right track. BTW I had a look at your website you have some nice very projects on there. Great photos too and the finish you get on your parts looks brilliant.

Well a bit more progress today but I spent most of my time trying to set up the part ready to machine. I'll show you how/what I did to set up for an off centre hole but would welcome comments on how you would do it if you have a different/better method.

First off I marked out the stock with blue marker, scribed and center punched it.

Then I set up the lathe like so

Then I spent quite a long while trying to get the center dot to line up with the point of the center.

This picture shows the outcome I drilled the hole with a small centre drill

It is on my scribed marks, (Ignore the milling mark just above it.) But I found it very difficult to see that it was in the right place. In the end I decided to give it a try and it came out OK. But getting my eye into the right place was very difficult. I used a 10 x Lupe but as I can't get to see all around the hole very easily and at that mag the pop hole looks a bit ragged anyway. The lathe tailstock is in the way and the cross slide blocks the bottom of the chuck. So all in all I found it was not easy thing to set up.

Here is my pilot hole

Finally I'm ready to drill out the hole ready for me to bore it to final size. I'm using the tape as a simple depth gauge.

My method worked but is there a better way to do this off centre type of a set up?

Nick

 

[mklotz]

My method worked but is there a better way to do this off centre type of a set up?

What you need is a "pump center". Here's a thread where I show mine in use...

http://www.homemodelenginemachinist.com/index.php?topic=3859.msg39487#msg39487

but use the search function and you'll find other references to it.