single valve, vee twin comp. air eng.

[hobby]

Most of my engines used a spring tension valve system, so when the air intake stops the engines would stop rather abruptly,
my very first engine I ever built, and designed from scratch, was a double acting valve system, with scotch yoke connection for the valve.
When I apply air to it, it revs up very fast, and when I shutoff the
air intake, for a brief moment, the flywheel momentum goes rather strongly, so as air intake is applied and relieved, it gives a sound of an engine reving up, plus the air exhaust gives that puffing sound, so combining all that, I can make the engine sound like its reving up.

Now I just built a very quick one valving engine, with no spring tension for the valve system, but rather the classic eccentric/strap combination, this has a positive movement on the valve, both forward and backward in its cylinder, so with no spring tension, it has the ability to rev up and rev down with flywheel momentum, without stopping abruptly.

Here is that engine, I also built it as an experiment to see how painting my projects would work for me.


Now as I was playing around with my engines of late, I thought about building this same engine, since now I have all the location dimensions figured out for the valve holes, as well as the valve length, where it is machined at for the valving, the piston con rod length, and a few other major dimensions, already in working order, so with all this already established, I decided I want to build this type of engine again, only make it a twin cylinder vee design.

So here is the start of this engine build:

since this is designed to have both the piston cylinder sleeve and the valve cylinder sleeve, in the same round block, I needed to use my 1-1/2" round bar I have on hand.
This dictated the whole design of my engine shown above, If I had something of different size, the design would have gone that dirtection instead.
Because I am using a bar stock bigger than my 7x10 mini lathe steady rest could handle, I have to use my shop made steady rest to handle stock up to 2" in dia.
here is one of the cylinders housing being faced off to length, in the steady rest.


once they are machined to length, I need to drill 6 holes at 60 deg. on my rotary table, around the perimeter, these holes will be tapped to 2-56 thread.
So after some elaborate clamping to the vee blocks, I then proceeded to tram in the round workpiece to center of the rotary table.


now all the holes were drilled at 60deg. increments, these holes were drilled a certain depth for tapping, then finished off with a body drill for a 2-56 screw to a certain depth for the screw to pass through part way. The reason for this is because I am going to cut this section away to be screwed back on as a cap, and the reason for that, is, because it is easier to drill and ream a through hole for the valve and piston cylinder sleeves to fit into, then to drill a blind hole.
The valve cylinder sleeve will go all the way through, but the piston cylinder sleeve needs to be capped off after the hole has been drilled and reamed all the way through.


now back to the lathe to center drill for a tailstock live center support


so I can machine down the dia. to form the cap for the housing.




when I cut the caps off thees housings, I want to make sure they go back on in the right order, so using my number punches I marked each housing side with its appropriat cap that will later be cut away.


they housings to thios point ready to have there caps cutaway.


now marking off the thickness of the caps, for the housings.


And my wonderful benchtop bandsaw, this machine ranks up there with my mill and lathe for accuracy, in cutting to a line. If I have real heavy rough stock to cut to rough length, I use my 4x6 vert/hor. bandsaw in my shop outside shed, but when I need a accurate cut where very little machining on the mill is needed I turn to this saw to get the job done.


I have discovered how well flycutters work when you sharpen them, so I use flycutters alot in my mill, but this time my flycutter set is to small for this workpiece, so I tried using my boring head and it worked perfectly.




ok the caps are cutaway, again this is so I can drill and ream thru holes for the cylinders sleeves, then cap off the housing to close up the piston cylinder sleeve.


It's time to drill and tap the holes in the housing body to be able to attach and screw down the caps.




and a trial fit of the housing cap screwed together with its body.


I do want the valve cylinder sleeve to protrude the housing cap, so with everything screwed in place tight, I begin to drill and ream for the valve sleeve hole.






Now after all that is done, with the valve sleeve hole, with the cap off I can start drilling and reaming the piston sleeve hole, remember the valve hole was drilled through the cap, but this piston sleeve hole is drill with the cap off, so the cap can cover up the piston hole during final assembly.




here are both housings done with the sleeve holes drilled and reamed to final size,
the one on the left, is the top side of the housing when fitted to the vee block, the one on the right is the bottom side, facing the crankshaft.


ok with all this talk about sleeves, its time to start making them, here is one of the valve cylinder sleeves being machined to outside dia, producing a flange.


now the inside dia. drilled and being reamed to final inside dia.


the best way to make this sleeve permanently stay in the sleeve housing, is with zap a gap super glue, this works excellent for my applications.




here is a blurry pic, of the housings top and bottom with there valve cyl. sleeves glued in.


Ok now before I work on the piston sleeves, I want to drill the valve holes for the intake and exhaust, wich will now pass through the valve cyl. sleeve, and into the bored out hole for the piston sleeve. The reason I can do this, is because the piston sleeve will be cut short in length so these holes will not be covered up by the piston sleeve, when I later insert it in to this hole.

So now some carefull lining up the valve bore with the piston bore,


my 'mad' (manual aided drafting), of this part to be machined,


and the drilling of the valve intake and exhaust holes commences.


I'm tapping 8-32 thd. these holes for later fittings so both housings can be connected through some sort of a intake and exhaust manifolds system.




Now I can start machining the piston cyl. sleeves, first the ouside dia. to make a flange.


and a test fit with its housing

and thats all for now.

since this is a project for weekends it will take some time, I'm not going to rush it, but do a little at a time, so the next post may be some time next week.

Have fun in the shop...
　
　
　
　
　
　
　

 

[hobby]

this evenings progress
　
next I started the drilling and reaming the piston cylinder sleeves, to an inside dia. of 0.376".




here is where I can chaeck the length, against the intake valve hole on its housing, as long as this sleeve does not cover up the first hole then it is the right length.


dry fit it to its housing, along side the glued in valve sleeve.


before I glue the piston cyl. sleeve into its housing, I'm going to machine the valves themselves now, this is made from 1/4" dia. steel rod available from "lowes store" There cut to around 4" in length, and faced off at both ends.


Now the intake and exhaust clearance is machined into its appropriate position on each rod.

　
have fun in the shop...

 

[robcas631]

Simple amazing! Wonderful work!

 

[hobby]

Thanks Rob,

I was able to get a couple more hours in yesterday,

I next needed to machine flats on the valve rods so they will fit in between the eccentric strap connector, these flats were milled down to 1/8" thick, then a clearance hole was drilled through for a 4-40 screw to act as a pivot, for the valvew rod, and the eccentric strap.






Over the summer I machined a bunch of pieces for engines, mainly to make up crankshaft journals, and eccentric and straps assemblies, plus a lot of connectors for piston rods and valve rods, ect...


so now I can pull out a eccentric/strap assembly, and a connector, for each of these valves I just machned.
Here are the parts needed for one valve system before final assembly.
The connector will be superglued to the eccentric strap, and the valve rod will attach to the connector with a 4-40 screw and nut, to act as a pivot.


That's all for this weekend,
have fun in the shop.
　

　

 

[hobby]

Some more shop work this evening,

I superglued the piston cylinder lining into the housings


Now that both liners are securely glued to the housing, I can take the top of the housing off by unscrewing the screws,


then superglue the housing tops on,


And temporarily tighten down the screws for a minute or so, these act as a clamp until the glue sets.


Now in that last picture was my screw container, that's because I'm going to remove 4 of these screws off of both housings, to conserve my hardware, the glue will hold tightly, no need for all six screws anymore, however I will still use 2 screws per housing, just to keep evrything in place under air pressure, should the glue fail. These 2 screws are backups.


Now its time to layout the cylinders housings,for fitting to a 'Vee' type configuration frame.
So I laid out approximately where they would go, using the ruler markings on my cutting matt.


Now its time to commit to a drawing out of where the parts will go.






And now setting them on the blank workpiece.


And some scribing on the workpiece for referencing, when I do the actual machining on this workpiece, I'll use edge finders and dial indicators to get exact locations.


First off I want to drill holes for 4-40 screws to be used as fastners to hold the housings to this soon to become top chasis. Later these holes will either be tapped for 4-40 screws to cinch the cylinder housings, or thru holes with 4-40 threads in the housings themselves, I haven't decided yet on that part of the assembly.


Next after carefull locating, I'm drilling pilot holes where the cyl. housings will go in this top chasis.
I will take the chasis to my drill press and use a 1-3/8" holesaw to do the initial hole cuttiing.


But before I do that while I have my vise still on my mill table I'll mill out the slot on the backside of this chasis, this slot will act as a dado, to recieve diagonal bracing later on in the assembly, of the chasis.


check for fit with a 3/8" square rod.


Now I can bore out the 1-3/8" hole at my drill press, my drill press has a heftier motor to handle this kind of load.




My cyl. housing is around 1-1/2" dia. so I purposedly used my smaller holesaw 1-3/8" to do the initial hole bore, so I can use my boring head on my mill to get the exact sliding fit I need by sneaking up on the final inside diameter cut.






Not quite there yet, a few thousands more should do it.


There a good sliding fit,


Next, after the other hole is properly bored to size, will be to make a very deep groove down the middle, on the top side of the chasis, to prepare it for the Vee configuration.

have fun in the shop.
　
　
　
　
　
　
　
　
　

 

[hobby]

　
　
Now it's time to turn it end for end to finish out the second hole bore, however I need a way to locate it without having to dial it all in again, as the first bore, so I temporarily clamped a test indicator stand on the trable and set the arm tight against the workpiece to act as a stop for the second side to be machined.


After that I need to drill clearance holes in the dado,


for 4-40 screws, these will be used to fasten the angle brachet to the top chasis later during asembly.


Now I can start the milling of the middle slot between the cylinder housings bores, on this top chasis.




check for correct depth of 0.250"


I would like to trim the corners of the top chasis, in front of each bore, so I'm using my angle bars to set up 45* tape them together to keep them from moving, and tape this all to the workpiece, using a square to keep the bottoms flush witheachother.


here is a pic. on the backside of this setup.


now guaging and marking off distances


I can now plum a line down and mark it off for cutting this off the corners.




Now using a square ontop of my bandsaw vise I can locate the square against the bandsaw blade.


line up the workpiece to this squares location.


and cut the line.






again at my mill table I use a combo, of my angle blocks to set the workpiece at the desired angle of 45*


so I can flycut and dress up the bandsawn edges.


Now I can use my slitting saw to cut the required depth of cut in the middle of the workpiece where I originally made the groove with my milling cutter.


That's all for this evenings take on this build, next will be to work more on the top chasis, preparing it for the cylinder housings.

have fun in the shop.
　
　

 

[hobby]

After cutting both sides of the top chasis apart


I can now fixture both halves together clamping them to a pair of 123 blocks, and setting them with the 45* angle of my combo head, now I can begin plotting measurements,


This is the cross bar bracket workpiece in place in the dado's with a straight edge,


for marking out the angle for cutting,




these are my layout tools too work this procedure, I feel that layout and jig/fixturing is just as important in the build of a project, as the project itself, for me, accurate laying out is about 50% of the machining process.


I now need to setup my angle blocks to give me 67*, so I just tape them together to make any angle I need within 1* increments.

This puts my layout line close to plumb,


so I can use my saw to get me a vertical cut on the workpiece at 67*.


Now I need to layout for the next length of cut on this workpiece, so by using the assembly holes I can guage the length needed,




now I can take the piece I cut off the other end


and use it as a template to know where to make the marking out for the next cut line.




now the workpiece is cut to rough length


just a quick dry fit


to check alignment with the top chasis


and the angle of inclination


and a quick dryfit to chack included angle of the cylinders housings with eachother


Here is a comparison of the same engine as a single cylinder, to the vee twin I'm now making.


have fun in the shop....
　

 

[hobby]

I have done all my other engine builds mainly with my computer to do the drafting with, this time I'm using my drafting board, to get the dimensions I need to make the next part.

This next part is going to be the connecting frame , which will tie the top cylinders chasis to the crankshaft base.
Here is the procedure to determine the length of this frame piece, as well as where the crankshaft center will be located.
So first I need to draw a horizontal reference line


and a vertical center line


here is the 2 reference lines


I have determined through the machining process of the earlier parts that the cylinders will be 45* offset from eachother, so I need to mark on the horizontal ref. line 22-1/2*, in order to do that, I bring the straight edge with the protractor down until the protractor is lined up on the 22-1/2* mark with the horizontal ref. line, right here,


and then I mark out a ref. horizontal line at the protractor here,


then I go back and mark out an arc on both sides of the protractor curve where they touch the original horizontal reference line, like this




now I draw a diagonal from the top ref. line and center to these 22-1/2* markouts,


like this


now I can secure the measurement of length of the top chasis half


and make a witness mark half that distance, on the drawing


and now at these marks I draw a perpendicular line, to represent the center of each cylinder


Here where they cross at the center line,


is the location of the center of the crankshaft, so can mark out a 1/4" circle to rep. the 1/4" dia. crankshaft.


Now with one of the workpieces in location on the drawing,


I can mark off the very top of each chasis part, like this




Now in order to determine actual dimensions from the center of the crankshaft to the top of this frame, I need to consider this dado that was machined in at a depth of 130. thou.


now I can add this depth facet into the drawing.







　


now a measurement can be made from the top of this dado, to the center of the crankshaft like this


and it shows 2.70" for that dimension at the right of the drawing.


now I can draw vertical lines from each end of the dado,


and guage the distance in between,


this gives me the width of the frame,


now I can line up my workpieces used for the cam eccentric and crank journal,


to evaluate the clearance needed to fit these into the framework, some where around here will be the bottom distance of this frame design.


That's how I do my cad drawings, on my computer, doing those kind of procedures, but I'm learning more how to do the drawings manually, it's a lot of fun.

have fun in the shop...
　

 

[hobby]

Now I can mark out to make the frame that holds the cylinders,

After I used a holesaw to cut this large hole, I'm now doing a quick check for clearance with the crankshaft.


Now some decorative milling in the frame blank.




now to cut it too rough shape, at a 68* angle, using my bevel square I can set this up on my bandsaw.


I have to show the accuracy of these kind of benchtop bandsaws, look at this nice thin slice being taken off after I roughed it out, I want to take more material off before I finish it on my milling machine.


Now I can do the finish work on these cuts on my milling machine, I'm findinfg a lot of use for my angle block set, now that I found a trick of keeping them together with masking tape.
This sets up the work piece at 68*.


Now I have a dodo milled into the top cyl. chasis, this dado will fit over this frame keeping it all aligned, so here,I need to secure the depth of cut.


and now the milling away of this material, the reason for this procedure is, the dados are 3/8" wide and this frame is 1/2" thick, so I need to take off around 1/16" off of both sides.

dfryfittingf it.



now I can square up this workpice on these angles to finish milling the sides to there proper angles.


Now some dryfitting of the parts machined so far.








That's all for now,
have fun in the shop....