Engine Number Two

[ProdEng]

All of the bits I make in my workshop start with a 3D model, I use Autodesk Inventor, a program that I love dearly. 3D modeling allows you to check the fit and alignment of all components, just like putting the metal together, along with the near automatic production of accurate working drawings. For engine 2 I chose one of Rudy Kouhoupts engines, a simple horizontal from The Shop Wisdom Volume One. I have already made a few of the parts for this engine and fortunately took some pictures along the way. I have included the 3D model and a picture of the oil cups for the main bearings. The oiler is 5mm diameter and has an M3 thread (3/16", #5) and is not part of Rudys design.

 

[b.lindsey]

Ain't no grass growing under your feet then is there Jan :big: Great job on #1, and #2 should make a fine model as well ! Keep up the good work!!!

Bill

 

[ProdEng]

This design of engine has a conrod and eccentric rod made from 1.5 mm (.060") aluminium sheet, not the easiest material to hold to work. I wanted to machine the holes and sides of the rod in one setting so simply screwed the sheet to a block of wood and clamped the wood in the vertical slide. The conrod sides where milled using a 2mm slot drill held in an ER32 collet chuck. With the eccentric arm the block was moved to the four jaw chuck to bore the larger of the two holes. The boring bar is ground from 1/8" HSS. The ends of the eccentric rod where filed to shape. I would be interested to hear if anyone has an alternative way of holding such a thin workpiece.

 

[miner49r]

So far, so good Jan,
I see that you only used three jaws on your chuck to hold your wooden block. That "could" end up being a problem and "would" have if it was me doing it. Murphy's Law is always my partner in crime.
Two option that I would consider would be to screw the block to a face plate or reverse the jaws of your four jaw chuck to grab the block at four points.
Alan

 

[ProdEng]

The fourth jaw would have been ideal but the chuck is too small. The wood is in fact only gripped by two jaws, the third one, which is reversed, only provides support at the back to prevent the block twisting. Wood crushes as you tighten the chuck and is surprisingly difficult to move. I guess the ideal way to have done the job would have been to leave the work in the vertical slide and use a boring head except that I don't have one. It seems like every time you want to machine anything you have to buy an extra tool!

 

[ProdEng]

My vertical slide is a Taig model and the fact that it is made of aluminium reminds me that it is for light duty. I found that mounting the slide in a fixed position was very limiting so made a tooling plate up that allowed the mounting of the slide anywhere it needs to be and also allows workpiece mounting for line boring. The tooling plate picks up the top slide mount and two additional holes tapped in the cross slide.

So far this arrangement has done all I need and even the next engine I have in mind can be completed with this simple equipment.

Using the slitting saw on the steel piston was a bit noisy but I just applied full depth of cut and wound on the cut reasoning it would either work or break! The gears in the headstock of the C3 are not the best for this kind of work and I would consider changing to belt drive just to get rid of the gears.

 

[ProdEng]

This engine uses a piston valve so the cylinder needs two bores. I made the valve bore 5mm with a reamer while the piston bore was bored with an HSS tool. The boring bar is ground from a 1/4" toolbit and took forever to grind. The boring bar has a lot of spring in it and tends to cut a bit of a taper so when the bore is size you need to feed the tool in and out a few times to let it finish cutting. On this occasion I traversed in and out five times and it still kept producing swarf. After all that the bore was still slightly tapered because of the "quality" of the machine. Never mind a quick lap fixed that.

Jan

 

[ProdEng]

Had a weeks holiday last week so got to spend lots of time in the shed. Work came along slowly but surely and at the end of the week I put the bits together to see how it looked. Still a fair bit to do on the flywheel and need to make the eccentric and valve piston.

I decided to use bushes for the crankshaft and made them a bit wider than the bearing blocks to provide thrust faces for the flywheel and eccentric. The bushes where pressed in with my toolmakers vice which had arrived the previous day.

Jan

 

[b.lindsey]

You made a lot of progress over the week's holiday Jan...its still looking great too!!!
Bill

 

[ProdEng]

Thanks Bill, it was a fun week and I look forward to the next one! Best part of the weeks work was feeling more comfortable with my machine and tools along with a growing enthusiasm for more ambitious models. My initial plan was to mill on the lathe only but my sights are set on a mill, for acquisition soon

Jan

 

[b.lindsey]

Having a separate mill will open up a whole new world of possibilities and ease of doing some things too...not to mention a great excure to purchase even more tooling :big:

 

[peatoluser]

I sympathize with your boring problem. It's the same with me. I sometimes wonder if the damn thing will ever stop cutting , because no matter how many times I feed it in and out , it always seems to want to cut just a little bit more!

I too have one of the taig milling slides, although you seem to get more use out of it than I do mine!
one thing I did fit on mine was a 4 by 4 by 1/4 plate peppered with M5 holes bolted to the face, much like the base you bolt your slide to. It is set square to the slide and has a narrow fence bolted to the bottom edge to help in setting work parallel. I find it more versitile than the vice blocks that come with it. For cutting more robust material it's probably more stable than wood, although I doubt it would have been quicker to set up than your block of wood for milling the eccentric rod.

in fact , i quite like your use of wood for holding parts. It's an often overlooked material but very useful for us homeshop machinists.
looking forward to more posts

yours

peter

 

[ProdEng]

A tooling plate for the vertical slide is indeed the way to go and I completed mine at the end of last week as I was waiting for a counterbore to arrive! Still need to make the studs and clamps up for the whole setup. Seem to spend more time on tooling than making engines at the moment.

With thin material I have still to see a better way of holding the workpiece than a block of wood. Packing 1.5mm aluminium off a mill table and clamping it sounds like hard work to me and transfer to the lathe would have been more difficult also. I hasten to add the the wood was well prepared with the two faces and one edge dead flat and square. While in my shed, I see my self as a model maker rather than a machinist so unorthodox methods are allowed ;D

 

[ProdEng]

A lot of time spent and a little bit achieved. Making the flywheel from solid was always going to be a lot of work and I nearly gave in and drilled a few holes and left it at that. However spokes look so much better so I decided to have a go. As no millling machine and rotary table is available this was going to be a drill, cut and file operation. For marking out I used a paper template drawn in AutoCad with the centres of the circles marked. The paper was stuck to the flywheel with artists spray adhesive which work well. The holes where then centre drilled and drilled. The space in between was cut out with an Abrafile, a tool no longer made sadly. I experimented with a dental burr mounted in a Dremel and that also works quite well. My expectation was that the cutter would wear very quickly but it lasts well. A lot more filing now to be done so it will not be finished soon

Also turned the eccentric, no pictures as it is pretty simple. For this part I found some leaded steel and was stunned by how easily it turns and well worth the money. Before I can machine the valve piston I need to make some clamps to fit my toolmakers vice to the vertical slide.

 

[ProdEng]

So with clamps duly made I started on the valve piston. Milled the step in the end first with a 6mm endmill followed by the slot for the eccentric strap and finally turned the groove which governs the timing. The 2" toolmakers vice was a good buy and makes life a bit easier than no vice! All the bits are made now so it is a question of making all the parts play together.

Decided to buy a mill after all so a Sherline machine is on its way, yipeeeee!!! No doubt that will be followed by a rotary table and who knows what else in due course. So it looks as if the little engines have bitten hard

 

[arnoldb]

That's coming along nicely Jan Thm:

;D And a mill on the way too - you'll really enjoy having it. It's fine milling in the lathe; I did that too when I started out, but having a separate mill is just so much more convenient and stable.

Kind regards, Arnold

 

[b.lindsey]

Jan, I think you will enjoy the Sherline mill and find many things easier to do. A rotary table will add even more and one thing I would encourage you to do if possible (assuming your lathe chuck is threaded) is to buy or make an adapter that allows the lathe chuck to be mounted directly to the center bore of the rotary table. At least you can do that with the Sherline RT. That way you can do turning or boring work on the lathe and transfer the part to the mill without ever having to remove it from the chuck, which does wonders for maintaining concentnricity, etc.

Great progress on the engine....still following along every step of the way.

Bill

 

[ProdEng]

Bill, my lathe has a bolt on chuck but an a adapter should be easy enough to make. I have my eye on a Vertex RT, it can be mounted horizontally or vertically which is handy. I enjoy working with hand tools but it does sap the energy and I would rather save the saw and file for occasions when machining is not possible. Sawing and filing one flywheel was enough to convince me to get a mill or else make engines without flywheels

Jan

 

[dgjessing]

The main purpose my milling setup on the lathe served was to convince me to buy a mill

 

[ProdEng]

Setting up a milling job on the lathe is not too bad but the 65mm travel of the cross slide limits you to small parts and that is the main reason for the mill. For small engines the biggest problem arises when you make an engine base which is almost always too big for the lathe. Anyway now I will have a choice of machines to use and avoid the frustration of setting up to mill and finding you need to turn instead ???

Jan