Model Engine Maker
Engines => From Plans => Topic started by: toolznthings on January 25, 2018, 05:06:26 PM
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Hello All !
Just finished my build of Elmer's #13 Vertical Poppet Engine, double size. Thanks to Julius and his drawings I used his assembly views and modeled
the cams similar to his metric version. I used the original English dimensioned drawings and doubled the sizes. I also made different versions of the connecting
rods and other modifications that I will point out as I post the build progress.
My friend and fellow forum member Yogi also found out what turned out to be a design flaw, at least in the double size of this engine. This proved to be true at the
end of the build when trying to run the engine. That's when he told me, he's still my friend ! :stickpoke: Since there is only a intake valve and no way to release compression on the piston up stoke the engine locks up and will not move until the trapped air bleeds off then locks up again. We came up with a couple of solutions that I will show later. There is a YouTube video of a regular size engine running so this may only apply to the double size. Looser tolerances on the pistons and cylinders or their volume may be the difference.
The engine has 1.750" diameter pistons with a 1.750" stroke. My crankshaft is about 11" overall long. Engine width 5 1/2" x 6 3/4" long x 10" high.
I'll start with the crank build on my next post. A whole story by itself. ::)
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Will be looking forward to it! Just looked up the original plans...yours at 2X scale will be a sizable model given the dimensions you stated.
Bill
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Building the crankshaft .......
I started by making the steel blanks for the throws to size and square on the mill and surface grinder. The center throw was made in a rectangle .875" thick x 2.750" high
and 1.594" wide. End throws are .625" thick .875" wide x 1.875" long.
With a mill stop in place and the hole location established on the center throw I spot drilled, rough drilled and used a under size end mill to flat bottom the bores. I decided to use blind holes in the throw rather than through bores as shown in the original plans. Flipping the part against the stop for each hole.
Using ground .500" diameter 12L14 round stock for the journals the bores were sized to allow a bare slip fit with no " wobble " to the mating part.
Similar operations were made to the end throws. These bores are through the part.
The center throw profile was next. A layout was made and the excess stock was band sawed from the blank. Set up on a sine bar to mill the remaining stock within a few thousands of the the layout line. At the surface grinder the final size and finish was completed.
Another setup was made at the grinder to add the 45 degree chamfers where needed on the throws.
Some finish bench work and the journals cut to length the parts were ready for assembly. A " U " shaped spacer was made to establish the distance between the throws where the connecting rods fit. A slight groove was file in the bores to allow air to escape when using Loctite. All parts were primed with Loctite primer and the crank was assembled in stages. The final assembly was done on a small granite plate to insure everything was in alignment.
The end results were excellent with the crank running true. :) All done, well not quite ! Later on in the build the joints slipped and threw the crank all out of alignment. :facepalm:
After two separate attempts and some time later I finally was able to save the crank without starting all over. Might have been easier !
The " new " crank shown later in the build has .562" output ends made from W1 drill rod due to resizing the end bores during the fix and I thought would be a little stronger, too.
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More crank build pictures .......
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Some more pictures ............
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The last ones ............
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Lots of nice work there! I like seeing the use of the sine bar and tall jaws.
Dave
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What caused the joints to slip? Was the Loctite now fully set yet or other reasons?
Bill
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Hi Bill,
Not totally sure what happened. I applied some air to the engine to see if I could get some idea about movement when it happened. Maybe to much force at the wrong position of the crank or my Loctite was to old. Did not move it much, but a little was the end of the alignment. Difficult working backwards to fix.
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I'm glad we are still friends Brian! :stickpoke: :Argue: :hammerbash: :lolb:
Great write up, with lots of pictures. I'm looking forward to the build.
Yogi
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Nice work on the crankshaft! Too bad it didn't hold up...
From what I've seen, this engine is a uniflow steam engine. These have some compression by nature. One way to deal with that is to make some dead volume in the cylinder. I'm curious to see what you did and looking forward for the next post.
Keep the pictures coming :popcorn:
Plani
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I'm glad we are still friends Brian! :stickpoke: :Argue: :hammerbash: :lolb:
Great write up, with lots of pictures. I'm looking forward to the build.
Yogi
Thanks ! Just barely :lolb:
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Nice work on the crankshaft! Too bad it didn't hold up...
From what I've seen, this engine is a uniflow steam engine. These have some compression by nature. One way to deal with that is to make some dead volume in the cylinder. I'm curious to see what you did and looking forward for the next post.
Keep the pictures coming :popcorn:
Plani
Thanks ! The reworked crank actually came out better. Became a career project ! :)
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Making the base plate for the engine from a piece of mild steel stock I had left from another job. Milled the outside dimensions to size. The plate is about 5/8" thick and the overall size is 6" x 8". Used a corner rounding end mill to put a 1/4" radius on all the corners. The plate had a blanchard ground surface and was not quite flat so a quick grind of one face was done for flatness and it removed the rough finish. This part will be painted before final assembly.
Four 1/4-28 tapped holes was the last operation. These holes are for the engines " feet ".
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Machining the engine feet and bearing blocks for the crank ......
These parts are made from cast aluminum jig plate.
Doing the bearing blocks first and in pairs the width is finished to size of 2.500" and the overall height left long for later operations. The material is .750" thick.
The steps for the mounting holes were mill next with a final width of 1.500" centered on the blank.
The engine feet were done in pairs also and measure .750" thick x 1.500" high x 5.500" long.
The steps for mounting were done to a final width of 4.000" and centered.
Next operations will be drilling, tapping and boring.
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:ThumbsUp: :ThumbsUp: :ThumbsUp:
Coming along nicely.
Keep the pictures coming. :popcorn:
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More machining on the engine feet and crankshaft bearing blocks .....
Clearance holes for 1/4" bolts were drilled in the feet where they will mount to the base plate. The top side of the feet has 1/4-28 tapped holes for the columns and 10-32
holes for the crankshaft bearing blocks. This finishes the feet.
The bearing blocks had 13/64 clearance holes drill in the tabs. Then set up in the mill for rough drilling and boring for the bronze bearings to be made later. A ground block balances the vise at the far left.
At the CNC mill the blocks are held in position on a small setup plate and the bore swept for part zero. A small clamp was then added to the setup through the bore.
This operation finished the contour shape on the top of the blocks.
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Machining the base plate that mounts to the engine feet and the 660 bronze bushings for the crankshaft bearing blocks.
The base is machine from cast aluminum tooling plate and the overall size is .750" thick x 4.000" wide and 6.750" long.
At the cnc mill the interior cut out was milled thru the plate. Mounting holes were drilled thru and reamed to .257" diameter.
Notches for connecting rod clearance will be milled later.
At the lathe 660 bronze bar stock was machined with the o.d. turned for a slip fit to the bearing blocks. The i.d. was bored to allow for .001" + fit to the crankshaft journals.
Parted off and chucked for a 45 degree chamfer at the bores.
Loctite with primer was used to assemble the bearings to the blocks.
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Alignment and dowel pins .......
Aligning the crankshaft bearing blocks to the base and adding .062" dowel pin reamed holes. The hole spacing will be different on each end so the parts are not interchangeable.
After this setup .125 dowel pin holes are placed thru the base into the feet and later before final assembly the feet will be doweled to the steel base plate.
Next step and modification is to add flat bottom counter bores to the base where the columns will mount. This will provide alignment for the columns.
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A couple more pictures ....
The crankshaft with the assembly for a trial fit.
Flat bottom counter bores with a end mill ground for this operation.
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More nice progress and you are getting a very nice finish on all the parts. Looks better that the picture in Elmer's book!! Still following along.
Bill
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Thanks, Bill !
Appreciate your interest . :)
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Machining the six engine columns ..........
Made from 1/2" diameter 12L14 stock.
Four columns pass thru the base and hold it to the engine feet. The center columns pass thru and are held to the base with a nut on the far side. The overall length was modified to allow for the depth of the flat bottom bores in the base.
Set up in the lathe using 5C collet and a spindle stop the overall length was finished on all the columns first. The following setups turned the .250 diameter for the 1/4"-28 threads.
Ends were chamfered for the thread and all the ends were single point chased.
At the mill with a 5C indexer and stop I added wrench flats to the columns. This was an additional modification to the build.
A trial assembly checking the results.
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One additional picture .......
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Those turned out beautifully toolz. 12L14 is nice to work with, just keep them oiled as it tends to rust easily.
Bill
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Machining the bottom plate that supports the cylinders.
Made from .250" thick tooling plate the overall size was machined to 4.000" wide x 6.750" long.
Using dividers a layout of the 1.875" thru holes in the plate was made and after locating the centers at the mill. Roughing out with a end mill close to the layout was done first.
The boring head was used to finish the thru holes first. The boring bar was ground to achieve a flat bottom bore needed on the next operation after the thru bores.
A counter bore of 2.000" x .062" deep was finished next. The cylinders will set in this counter bore.
A boring tool ground at 45 degrees was used to add a small chamfer to each bore edge.
The last operation added the thru holes for the columns.
The last picture showing a test fit.
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Things are starting to come together very nicely!!
Bill
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Laying out the holes and roughing them out with an end mill: Old school and very effective! I like it! :ThumbsUp:
Very detailed build. Thanks for sharing. :cheers:
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Laying out the holes and roughing them out with an end mill: Old school and very effective! I like it! :ThumbsUp:
Very detailed build. Thanks for sharing. :cheers:
When you're old you tend to " old school " ! :old:
Thanks for the reply ! :)
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Machining the bronze cylinders.
Using cored 660 bronze stock I rough bored the 1.750" I.D. and turned the 2.000" O.D. leaving stock to finish.
After the material cooled down to room temperature the O.D. was finished first. Again, waiting for any temperature in the part to cool before finishing the I.D.
I wrapped the part O.D. with a strip of rubber and secured with tape. This prevented any chance of chatter when boring to size.
Parted off leaving stock for finishing the cylinder to 3.250" long. The opposite end faced to the proper length to finish.
Did some polishing to the bore and broke any sharp edges inside and out.
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Interesting, never seen that wrapping trick, keeps the part from "ringing" as you bore it out to thin wall?
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Hi,
Exactly. Use to be common place operation when cars had brake drums and they were re-cut. They actually had a special band just for the operation.
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Nice! One more part in the finished pile :)
Bill
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Machining the connecting rods ...........
I changed the design of the connecting rods and they will also have split bronze bearing inserts with shoulders.
Started with making the blanks for the rods. The blanks are made to final thickness, width and overall length.
The end caps were made next and drilled for the mounting holes.
Doing both rods at once, tapped holes were added and the end caps mounted. Each assembly was then drilled and reamed for 1/16" dowel pins.
More machining to follow in the next posts.
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Connecting rods next step .........
Both the crank end and piston ends of the rods were bore to accept the bronze bearings.
Layout lines showing the piston end of the rods were laid out for reference the ends were milled to size.
Addition layout for the rod profile were done next and the rods were set up on a sine bar for the milling operation. Stops were set so the operations could be duplicated on each rod. A end mill with a hand ground radius on the corners was used to cut out the material to the layout line.
Stacked together the finished rod was used to scribe a visual reference on the second rod and it was completed.
The two rods finished milled ready for bench work later on in the build. Bearing machining will be next.
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Machining the lower split bearings for the connecting rod.
Making four bearings from 660 bronze at the lathe with flanges. The bores were rough finished in this operation.
At the mill the turned blanks were milled in half and test fitted to the connecting rods.
Assembled with the rod caps the final size of each bearing was bored.
The finished bearings and the rods.
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Connecting rod wrist pin bushings and the start of the engine pistons.
Set up to turn and bore the wrist pin bushings from bronze stock. The I.D. is sized for 1/4" dowel pins that will be used for the wrist pins. Turned for a slip fit in the connecting rod and held in place with Loctite.
The pistons will be made from 303 stainless steel. Turned, bored and finish faced to length in a separate operation.
First operation at the mill does the reamed hole for the wrist pin. Setting up in next operation to add set screw holes to secure the wrist pins.
More to follow in next post......
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Finishing the pistons with tapped holes for set screws to hold the wrist pins in place. Indicating to align and find center,the operation is completed.
Dowel pins are modified for the wrist pins. The overall length was ground to make the pins fit within the piston diameter. Next set up was made to grind two flats for the set screws.
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The pistons look great, but have to say that set up for grinding the grub screw flats on the writs pins look very tenuous. Glad you got it done without mishap.
Bill
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Hi Bill,
You are right, slow and careful on the grinding. The fine pole magnet helps for sure.
Thanks for the comment !
Brian
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I like what you did with the wrist pins there Brian. :ThumbsUp: :ThumbsUp: :ThumbsUp:
A grinder is sure a useful tool to have...
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Connecting rod clearance and the engine cams.
A trial assembly of the connecting rods to determine the location and depth of the notches to be cut in the base for rod clearance.
Set up on tilt table to cut the notches.
The cams are a variance of the design Julius made in his drawings and completely different than the original design.
The blanks machined at the lathe and set up at the cnc mill to machine the contour then at the manual mill to add the set screw hole.
A trial assembly with the cams, rods and some customs made brass spacers.
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Still following along....the finish on all these parts is just incredible.....well done!!!
Bill
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Still following along....the finish on all these parts is just incredible.....well done!!!
Bill
Thanks so much ! Appreciate you following and commenting !
Brian
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Machining the valve guide bracket.
I redesigned this part so the it will have a split type clamping feature to fit the columns with out set screws. This part needs to be adjusted on the columns and set screw marks into the columns would not be good. Final location is determined at assembly and during trial fits this part was removed numerious times.
Started with a long piece of 1/4" tooling plate. Setup the fly cutter to the correct radius and cut the arc for the bracket on each end of the blank.
Next operation was to bore the holes for the columns and a small bore in the center for a valve guide bushing that I added to the design.
Setup for a slitting saw, a cut was made to each bore to allow for clamping with a socket head cap screw.
Tap drilling, counter boring and tapping each location.
At the band saw the parts were cut from the longer piece leaving stock to finish the width. After the width was machined a 45 degree chamfer was cut on the outside corners.
Another trial assembly shows the parts mounted to the end columns. Easily adjustable and removable.
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Two more pictures .......
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Looks great Brian!
Dave
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Hi Dave ! Thanks !!
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Machining the upper valve plate, middle valve plate and lower valve plate.
Stacked all three plates together and machined the width and length in a couple of setups.
Individually spot drilled , drilled and reamed each plate .257" diameter to match the columns spacing.
The lower valve plate has two counter bores to match the 2.000" cylinder diameters. Machined with end mill to .062" deep within a layout line and the diameter finished with the boring head.
The other two plates had features milled for the valve guides to clear and air passages milled.
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Great Progress :ThumbsUp:
And a lot of really nice looking parts!
Plani
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Thanks ! Keep a eye on that Yogi guy, too ! 8)
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Machining the valve guide / seat ........
At the lathe the .188" thru hole for the valve rod is bored from both ends. The opposite end has a counter bore and the 45 degree valve seat. The O.D. is turned to fit the bores in the valve plate.
Next operation at the mill cuts the .062 slot which allows air to pass into the valve plate.
After some deburring the guides are Loctited into the valve plate to finish this part.
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Quick set up for exhaust ports and making the intake valves
Using a arbor in the 5C indexer to drill the exhaust holes. I did holes instead of a slot.
The intake valves are made from two parts silver soldered together. The stem is ground .1875" diameter 12L14 stock and the valve end from 5/8" to leave stock for turning. My simple third hand in operation. ( Hints,Tips & Tricks )
The next operation at the lathe is to clean up the bottom of the valve head. After this operation the valve was inserted further into the collet , faced to size and center drilled.
Re-positioned and supported with a live center the O.D. was turned and the 45 degree valve face was cut.
After finishing the overall length the 10-32 thread were chased on the end.
At assembly the valves will be lapped into the valve seat.
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Machining the flywheel ..........
The flywheel is my design and is 6" in diameter. After machining the blank at the lathe I broached a 1/8" key way thru the bore.
Setup at the mill for drilling and tapping for a 10-32 set screw hole over the key way.
I setup the crank shaft and cut the matching key way on both ends of the crank. Did a test fit to the crank.
At the CNC mill I made a setup to machine the spokes in the flywheel.
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After doing the necessary bench work and painting the flywheel is complete.
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That is a very handsome flywheel and the colour isn't half bad either ;)
You're really moving along on this build :ThumbsUp:
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Pictures showing all the parts with the finish work completed. This included any final deburiing , polishing , removing cutter marks and adding chamfers to the edges on different parts.
Made some custom size brass washers for the fasteners and cut all the dowel pins to final length where needed. The acorn nuts needed some work to make them presentable, too.
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Love that last family shot!! You should have it running in short order now I would think.
Bill
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Hi Brian,
It looks like another fine addition to your collection.
Give me a call when you get a chance.
gbritnell
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Starting the assembly .......
The hard part is not marking, dinging and scratching all the finish work when putting everything together.
The pictures pretty much describe how the first part of the assembly is done.
The base plate has been painted and ready for the lower part of the engine.
Lots of rags to protect everything when the connecting rods and pistons are installed. 8)
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BEAUTIFUL work :praise2: Terry
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With those nice finishes, I don't blame you for protecting everything. Looks great so far!!!
Bill
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More assembly ...........
Working the way up with the cylinders, pistons and valve/cylinder head plates. Another set of studs hold these parts to the lower assembly.
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The last part of the assembly ..........
Added a wood base and name tag to finish up.
To make the engine run since it has no exhaust valve and air is trapped in the cylinders on the up stroke I added a bleeder hole into the cylinders and capped off with two button head socket head screws that are drilled thru 1/8" diameter. Of course this allows a continuous bleed of air from the input air , but causes no problems. It actually adds to the sound of the engines running.
With its size this engine uses a bunch of air, but runs nicely at low speed. Top RPM is about 265. In the video a last minute addition is the gear on the other end of the crankshaft. Item found in my " never know I might need it " drawer. ;D
https://www.youtube.com/watch?v=NGGt8h_9tQ4
Thanks for all the views and comments ! All appreciated !
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Is that the right video? :headscratch: Ah...i see it just got fixed. Nice runner too!!! Is there no exhaust valve in the design or is it just something you haven't added yet?
Bill
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Is that the right video? :headscratch: Ah...i see it just got fixed.
Bill
Fat fingers at the keyboard ! ::) That's my next build sneak peek just for you ! 8)
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Is that the right video? :headscratch: Ah...i see it just got fixed. Nice runner too!!! Is there no exhaust valve in the design or is it just something you haven't added yet?
Bill
Hi Bill,
No exhaust valve. Engine won't run as built from plans without a lot of leakage somewhere. That's why I added the bleeder holes to the cylinders. You can see the button head screws in the video that I have drilled thru.
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I just pulled the book out and noticed that this is a uniflow design or sorts. Those holes in the sides of the cylinders are supposed to let the pressure out and Elmer must have assumed that with the valve closed there wouldn't be enough compression on the upstroke to offset the pressurized downstroke of the other piston. It would seem your experience proves this wrong unless changing to 2X scale had something to do with it. I should have looked at the plans closer before :)
Bill
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The last part of the assembly ..........
Added a wood base and name tag to finish up.
To make the engine run since it has no exhaust valve and air is trapped in the cylinders on the up stroke I added a bleeder hole into the cylinders and capped off with two button head socket head screws that are drilled thru 1/8" diameter. Of course this allows a continuous bleed of air from the input air , but causes no problems. It actually adds to the sound of the engines running.
With its size this engine uses a bunch of air, but runs nicely at low speed. Top RPM is about 265. In the video a last minute addition is the gear on the other end of the crankshaft. Item found in my " never know I might need it " drawer. ;D
https://www.youtube.com/watch?v=NGGt8h_9tQ4
Thanks for all the views and comments ! All appreciated !
Looks and runs great, nice slow speed running. Reading others comments I'm thinking that the double sizing is the reason you need the bleeders, you didn't make the exhaust holes big enough to let all the air out.
Doubling the size of the cylinders and the stroke more than doubles the volume in the cylinders, it 8 times it. If my math is right, the original design was about 0.7 cu inches per cylinder. Double the radius and the length, and now you get about 5.5 cu inches per cylinder. That's a LOT more air/steam to let out.
But, doubling the size of the exhaust holes only doubles the area allowed for air/steam to escape, so more air/steam is trapped in the cylinders, causing the backpressure. And to make matters worse, Elmer's design had a slot, while you drilled holes (which I think look much nicer, BTW), so your exhaust port probably isn't even twice his.
Not sure if making larger holes will help (or is even practical).
Thoughts? Disagreements?
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The last part of the assembly ..........
Added a wood base and name tag to finish up.
To make the engine run since it has no exhaust valve and air is trapped in the cylinders on the up stroke I added a bleeder hole into the cylinders and capped off with two button head socket head screws that are drilled thru 1/8" diameter. Of course this allows a continuous bleed of air from the input air , but causes no problems. It actually adds to the sound of the engines running.
With its size this engine uses a bunch of air, but runs nicely at low speed. Top RPM is about 265. In the video a last minute addition is the gear on the other end of the crankshaft. Item found in my " never know I might need it " drawer. ;D
https://www.youtube.com/watch?v=NGGt8h_9tQ4
Thanks for all the views and comments ! All appreciated !
Looks and runs great, nice slow speed running. Reading others comments I'm thinking that the double sizing is the reason you need the bleeders, you didn't make the exhaust holes big enough to let all the air out.
Doubling the size of the cylinders and the stroke more than doubles the volume in the cylinders, it 8 times it. If my math is right, the original design was about 0.7 cu inches per cylinder. Double the radius and the length, and now you get about 5.5 cu inches per cylinder. That's a LOT more air/steam to let out.
But, doubling the size of the exhaust holes only doubles the area allowed for air/steam to escape, so more air/steam is trapped in the cylinders, causing the backpressure. And to make matters worse, Elmer's design had a slot, while you drilled holes (which I think look much nicer, BTW), so your exhaust port probably isn't even twice his.
Not sure if making larger holes will help (or is even practical).
Thoughts? Disagreements?
Hi,
The problem is the air trapped on the upstroke. I have a close fit on the pistons and practically no air escapes quick enough to allow the next cycle. Forum member Yogi suggested more free volume above the pistons would probably work also, but a much harder fix since I was way into the build. I'm sure the 2X size didn't help either.
Thanks for the comments !!
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Nice runner Brian! :ThumbsUp: :ThumbsUp: :ThumbsUp:
The gear wheel adds a nice touch, I like it!
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Very nice engine!!
And it's running very smooth :ThumbsUp: :ThumbsUp: :ThumbsUp:
Plani
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Nicely done Brian!
Beautiful engine, and it runs as nice as it looks!
Dave
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So now the inevitable question....What's next ;D
Bill
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So now the inevitable question....What's next ;D
Bill
Hi Bill,
Well I got a oscillating engine ready for posting if anyone is interested. :-\ Kind of a neat redo from a slightly unusual concept.
Thanks for the reply !
Brian
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Post away Brian. Is that the one I saw a "preview" of the other day when you posted the video? ;)
Bill
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Post away Brian. Is that the one I saw a "preview" of the other day when you posted the video? ;)
Bill
Should be, in my confusion when posting. :o
Gather up my thoughts and resize the pics to post.