Wobble plate engine, Elmer's #14 (finished, with pictures & video)

[Metal Butcher]

Since I already down loaded the plans, and my mind is racing with ideas and other related thoughts, today counts as the official start of this build.

I have wanted to add this interesting engine to my collection for some time. It uses a unusual way to operate a simple cylindrical slide valve. Its not very complicated compared to many of the plans offered by Elmer. But the basic design principal is a good basis for customization.

I'll take my first cuts tomorrow since the shop needs cleaning, the machines need oiling, and there are a few tools and materials that fell victim to my last few builds and need to be ordered.

I need to appear busy and stay down in the shop as much as possible today, since "Honey" is home. I can hear myself saying..."Honey I have a lot to do to keep with the 'start schedule' I announced on the forum today". "Can you deal with it yours self?" "Sorry. but I'm very, very, busy". :

I'll make a few parts and drag my feet around tomorrow, when there are no witnesses around! :big:

-MB

 

[Twmaster]

And right back into the fray. This is an interesting engine. I'll be watching your build so I can shamelessly swipe some of your ideas...

 

[Metal Butcher]

And right back into the fray. This is an interesting engine. I'll be watching your build so I can shamelessly swipe some of your ideas...

If you "swipe", borrow, or use 'ANY' ideas 'I' post, you are required to send a few cutters, maybe some brass bar stock, or just plain cash in an unmarked envelope would be fine. Your choice! :big:

Seriously, "swiping" an idea would be seen by me as the highest form of flattery!

'Swipe away!" ;D

-MB

 

[zeeprogrammer]

I went to see what this engine looks like and I'm looking forward to seeing how you make the wobble plate.

I need to appear busy and stay down in the shop as much as possible today, since "Honey" is home. I can hear myself saying..."Honey I have a lot to do to keep with the 'start schedule' I announced on the forum today". "Can you deal with it yours self?" "Sorry. but I'm very, very, busy". :

Please keep us up to date with how well that works for you. ;D In my home, what I'm doing doesn't matter even if I'm busy with the most primitive of tasks. (IF you know what I mean.)

 

[Metal Butcher]

Today I started cutting 1/4" aluminum plates for my builds. Yes!, you read it correctly as written. To make this build a little more challenging and interesting I will be building two versions simultaneously. Version #1 will be according to Elmer's plans, and version #2 will be a horizontal-apposing two cylinder version. I drew up some rough sketches of the supporting structure to get the project off to a start by roughing out the plates. The minor details will be worked out as the build progresses. Risky, but with a little luck things will go well.

Sorry my "picture guy" was not available today, but the pieces cut today will wait.

-MB

 

[Metal Butcher]

#1 On Monday I band saw cut All of the 1/4" aluminum pieces from 4" plate. The picture below shows the condition of the scrap material I'm working with. Fortunately it measures up at .258" giving me enough material on both sides to fly cut the pieces and remove the deep scratches and pitting. The plate is a very soft grade aluminum that is nearly impossible to file smooth. I make due with what I have but sometimes wish that the 6 to 8 feet left of this "peculiar" material would simply vanish.

#2 The picture below show all six sides of the pieces for build #1 finished.

#3 All six sides of the 1/4" plate for build #2 'Opposed twin cylinder wobble plate engine' finished.

#4 Machining the wobble 'plates' was a simple matter of machining the OD to size, then center drill and drill its hole. Then cutting off the two disc's. The first two were under sized by .004" in thickness due to a pull that's created with the angled cut-off blade I use. I added that difference to the carriage movement on the next two and they cut-off at the exact specified 1/16".

Accomplishing the 'plates' offset to the hub was incredibly simple. I marked a dot on one side of each disc as a reference point. I held the disc with my left hand with its reference dot at the top(up) and to the left. I tilted it to the left and filed horizontally on the upper and lower half of the hole with a round file. It took only a few minutes to remove very little of each opposing edge to achieve the discs minor 1/8" tilt. I filed slowly and checked the fit a few times. This was the important purpose of the marked reference dot. This method allows for a smaller gap between the two parts which I believe produces a stronger solder joint.

#5 The 'hubs' could not be any easier. The hole was finish by reaming to assure a nice snug fit to the crankshaft.

#6 Both plates and hubs were fluxed and then clamped to a fixture plate. I used a 1/8" brass rod to give the desired lift on the plate. After an eye ball check the pieces were soldered together using a propane torch. You can still see the two reference dots marked on the discs, they assured the filing was done in the correct areas after stopping for a test fit.

#7 The heavy fixture plate acted as a heat sink that had a negative effect on the free flow of the solder by spot burning the flux. Quick and out is the key to a smooth joint. Not very neat looking joints, but a little sand papering should make them more presentable.

#8 This picture of the back side shows that the solder penetrated the joint and flowed all the way around. This is proof of a good sound joint. This is much more important than a cosmetic consideration that can be corrected as part of the finishing process.

The build is off to a slow but smooth start. 8)

-MB

-MB

 

[cfellows]

Nice progress, MB. Wish I had your get-up-n-go! I like that little fixture plate, too. I know, I get excited over the funniest things!

Chuck

 

[Metal Butcher]

Nice progress, MB. Wish I had your get-up-n-go! I like that little fixture plate, too. I know, I get excited over the funniest things!

Chuck

Thanks Chuck! I thrive on get up and go. The 'get-up' is the hardest part. But once I"m up I need to keep moving, but I move at a shamefully slow pace. I'm sure you heard the story of the tortoise and the hare. Well.. I'm no hare! Just an ornery persistent old tortoise!

About the work plate, sorry Chuck, its the only one I have. ;D Its a simple project you could knock out in an hour or two. It's 4" x 5" x 5/8" with 1/4-20 holes 5/8" CTC. I made 8 different length fingers and 4 step blocks with 3 steps at 2 different heights when they are reversed.

A 1/2" thickness and aluminum plate would be better, along with a smaller 1/2" CTC screw hole pattern. Also I think a finer 1/4-28 thread would give a better clamping feel' or even a smaller screw size. I made it to hold small pieces during machining. but I find other uses like today. It does a darn good job on walnuts too, when I forget to bring along the official nut cracker!

I don't use it that often, but there are occasions that its indispensable.

Take a break and make one, you'll be glad you did.

-MB

 

[gbritnell]

Hi MB, your idea for setting up and soldering the wobble plates came out great. It sure simplified the way they described it in the text. Per our conversation you should probably make the operating arms out of mild steel so that you don't have the same metals rubbing together.
gbritnell

 

[Metal Butcher]

Thanks George! I"m scraping the idea I had to 'beef' up the 'valve lever' as it would require a larger valve and valve body. I'm not that ambitious! I found a strip of tool steel 1/16" thick that will do the trick with a bit of heat treatment. My heat treating furnace has been idle for a long time. Time to fire it up and make the shop nice and toasty. Easier to replace a worn out wobble plate and hub. Sometimes I'll run one of my little engines for mindless hours at a time. I hate the idea of having to 'baby' one.

-MB

 

[zeeprogrammer]

That was great. Thanks for showing how you made the wobble plate. It was a good learning.

You said "a very soft grade aluminum that is nearly impossible to file smooth".

Why is that? It seems counter-intuitive to me...because I know just a tad more than next to nothing... ;D

 

[Twmaster]

No idea where he got his but a lot of the aluminum sold in places like Home Despot and Lowe's is some awful soft as rubber gummy narsty crud. Can't machine for crap. Loads up cutters....

 

[Metal Butcher]

That was great. Thanks for showing how you made the wobble plate. It was a good learning.

You said "a very soft grade aluminum that is nearly impossible to file smooth".

Why is that? It seems counter-intuitive to me...because I know just a tad more than next to nothing... ;D

With one swipe of a clean and chalked file you get a deep scrape(S) with a raised pile at their ends. Its hard for me to describe the problem. Its as if there are deposits of some hard impurity that catches on the cutting edge and drags along to make a gouge that is to deep to be removed with further filling. Fly cutting seems to work a little better, but it leaves hundreds of little sharp points on the surface,Take a close look at the photos I posted and you may be able to see some. However the points do sand off well. When I found it at a scrap yard it was a 12+ ft piece covered on one side with masking tape. It measures up a .258", and this is a very odd size and not standard. I have machined most of the standard grades and a few unknown hard grades. So I'm somewhat familiar with their characteristics. The soft grades are noticeably soft and can gum up a cutter under the wrong conditions, but this stuff is very strange super soft stuff that seems to have impurities through out. Maybe its some special alloy for forming?

Trust me, you would not want to deal with it!

EDIT: On the picture that showes (#2 column) you can see the larger points sticking up in the air. Its not good to run you finger across the surface and pick up slivers.

-MB

 

[zeeprogrammer]

Thanks MB and Twmaster.
I still have lots to learn about metals. This helps.

 

[Metal Butcher]

#9 On Wednesday's my shop time is usually very limited, since I have a full day running around doing weekly errands. With an early start and a few less stops I was able to manage a little shop time.

I started making the valve levers. Build #1 requires one, and build #2 requires two. I band saw cut 1/16" x 1/2" steel strip to length plus enough extra material an both ends for clean up and sizing. Below are the three rough cut pieces.

#10 First I side milled the end (one end) on all three pieces. I set up the first piece with its milled end against a work stop mounted to the vice, and took a light cut. After the hand wheel on the mill was re-set to zero, I removed the piece and it measured .029" over size in length. I dialed the hand wheel to move the table .029" closer to the end mill. After I took the cut the pieces measured up exactly 2.313. Next I set up the remaining two pieces on top of each other with their finished end against the work stop. After taking the cut all three pieces were identical in length.

#11 The 1/16" strip on hand was .500" wide. The plans call for the 'valve lever' to be .250" in width. I scribed a line to follow and removed most of the excess by free hand cutting it in the band saw using its vertical mode.

#12 The pieces needed to be set up in the mill vise to remove the rough cut edges and bring them down to .250" in width. This is a simple set up using parallels. The problem is that the work pieces are 1/16' thick, and my paralells are 1/8" thick. It became necessary to make a thinner parallel with a suitable height. Its almost a case of "you need one to make one". I took a thinner strip of metal and scribed a parallel cut line at a suitable height and did an eye-ball set up, and milled off the excess. It turned out to be way off in parallelism. After quite a bit of filing and measuring I had a pretty acceptable parallel that I could use.

#13 With a suitable parallel ready to do its duty, the milling on the pieces would be a snap. After cutting down the fist piece and measuring to get the proper cutter height, the other two were sized with a single pass of the end mill.

#14 The 'valve lever' blanks are sized and ready for the final machining steps that will be done another day.

#15 In the first paragraph of today's post I mentioned my busy Wednesday schedule. One of the most important stops is my scrap yard visit. I didn't find any brass, but I saved a great piece of painted aluminum from the melting pot. Now it has a safe and permanent home in my shop. ;D

-MB

 

[Metal Butcher]

#16 I finished up the valve levers by drilling all the holes, milling 1/16" slots from both ends, and a little file work to create the radius's that allow the back and forth movement of the levers on the wobble plates. I decided against the heat treating that would probably warp the thin pieces. It wasn't worth the risk. The Opening up of the ends that ride on the wobble plate was very easy to understand. Test fitting during the process made it simple to see the areas that needed to be adjusted with filing.

#17 To mill the 1/8" depth in the head blocks (valve blocks) for their cylinders I lowered the end mill on to a .020" feeler gauge. Then I adjusted the rods on my mill to zero out my dial indicator. All that's needed is to add the .020" to the desired depth of cut. I use this simple set up to drill blind holes, and to mill pieces to proper height.

#18 Below is a picture of the set up I just described. The dial indicator is mounted to the threaded depth rod that travels with the quill. The long adjustable rod on the left is cross connected to the rod on a swivel rod bracket bolted to the head on the mill. I loosen the brass thumb screws to make adjustments, and to swivel the rod system off to the right, and up, when they are not needed.

#19 After I finished milling the three head blocks, the 1/2" x 1/8" recesses for the cylinders were cut out using a center cutting end mill. Instead of using a raised spigot indicated in the plans used to mount the cylinder, the blocks were made 1/8" thicker to allow for a counter bores to accommodate the cylinders. Below all three head blocks are being bored 1/2" x 1/8" deep in one set up.

#20 Using the previos vise set up, a step .250" wide by .1875" deep was milled off the front mounting point on the head blocks (valve body). This duplicates the original .3125" mounting height of the head block. Without this milled step it would have been necessary to change the length of the rocker arms and their pivot point locations. The milled steps made my alterations to the head blocks simple.

#21 Below the head blocks are being prepped for marking out the intake port locations. It turned out that the 'B' dimension was wrong and should have been .4219" just like dimension 'A'. Fortunately I caught the mistake in time.

Earlier I put the 'C' block in the vise facing the same direction as 'A' block, which would have incorrectly put the 'B' and 'C' blocks for the #2 build with one intake facing up, and the other one facing down.

#22 I finished up the head blocks (valve bodies) with all the needed drilling and every thing turned out well. The intake on the #1 (single vertical) build will be on the right side, and the intakes on #2 build (twin opposed) will both be facing up.

The reason the 'C' block on #2 build was made 1/8" longer, and that the cylinder was moved 1/8" away from the column, was to allow for the two 1/8" wide piston rods to fit side by side on the crank pin. All of the drilled port, intake, and exhaust holes are identical with their locations based on the front (column) side of the cylinder heads. On build #2 the intakes needed to both face up to be connected together and share a single and central intake pipe.

After the three near mishaps I had today, that started with forgetting to clamp the mill/drill head, I decided to call it quits for the day and post my progress.

After typing this post, I think my index finger needs physical therapy! :big:

-MB

 

[zeeprogrammer]

Great post MB.

For physical therapy I recommend swirling index finger in a short glass filled with appropriately chilled spirits. If you wash said finger first you can use the spirits to treat the rest of the body. ;D 2nd treatment is for internal use only.

 

[Metal Butcher]

#23 Today,s pictures and post are delayed by a day. I was busy painting replacement aluminum pieces that were damaged by recent high winds that went through my area. My house is shedding aluminum like a snake sheds its skin :big:

I trued up some scrap oversize brass rod that would become the cylinders to .5001" O.D. for a snug fit in the valve bodies. The cylinder bores were drilled under size and reamed to .375". afterward each cylinder was cut off at 1.1875" in length. The plans call for 1.250, but due to the cylinders modified mounting height on the valve bodies while maintaining the original head space above the pistons, the cylinder length needed to be shortened by .0625".

#24 The bores turned out consistent in size relative to each other. I gave them a light lapping with fine compound on a spinning cylindrical nylon brush to smooth them up a bit. There final measurement is just over 3/8" at .3752". So far so good.

#25 The pistons were machined from 6061 aluminum, not the best choice based an some recent posting on the matter. I have used this combination (brass/aluminum) in the past out of necessity without any noticed problems. But now I have some reservations. I machined them down to a .3745 diameter giving me a piston to bore clearance of just under .001". This clearance was my target and I couldn't be more pleased. These 'skirted' pistons are the smallest I've made to date. I was very careful not to crush their delicate skirts while clamping them in the mill vise, to drill the 1/16" wrist pin holes.

If the diy home repairs get done in a timely fashion, I should have more progress to post in a day or two.

-MB

 

[gbritnell]

Hi Rick, the engine's coming along great. I have to agree with you on the valve levers. Had you tried to harden them they might have warped.
gbritnell

 

[Metal Butcher]

#26 To make the piston rods I used scrap 1/8" brass plate. I marked it out with scribed guide lines for cutting in the band saw.

#27 The blanks were roughed out with a few minutes of free hand cutting at the band saw in its vertical position.

#28 The three blanks were brought to dimension using a 1/2" end mill.

#29 After drilling and reaming the crank and wrist pin holes, they became a convenient way to set up the pieces for milling their profiles. Using a 1/16" pin in both holes gave the pieces a slight taper in the set up, and added to the other wise plain looking rods by adding a bit of visual detail. I scribed stop lines as a rough guide, and used the calibrated hand wheels to get the exact stop points needed to mill out the areas between the pin bosses. This gave me identical profiles cut on both sides of the three piston rods.

#30 After a bit of filing and sanding the piston rods were finished. I'm pleased with the results. Below is a picture of how they look finished.

#31 To make the valves for both builds three 3/16' round brass rods were cut to equal length. Guide lines were scribed to aid in preventing an error while machining out the recessed air passages. I posted the two calibrated moves needed on the lathe for quick reference. After the carriage and top slide dial indicators were zeroed out, they guided me while I machined out identical recesses on all three valves using a 1/16" parting tool.

#32 After the machining was finished on each valve, they were left in the chuck. With a protective paper towel placed over the ways, and with the lathe turned off the valves were polished shoe-shine style with #400 sand paper by repositioning the chuck a few times by hand. This is one of the methods I use to finish a piece safely. If a lathe turned piece needs filing to round out or break an edge, I simply chuck it into my slow and weak (like me) cordless drill and do the finishing at the work bench.

#33 The picture below shows the valves ready for the next machining steps.

#34 I set up each piece in a square collet block clamped into the mills vise. I used my edge finder on the work piece to zero out on its edges, and made the appropriate moves using the calibrations on the mills hand wheels to properly locate the 1/16" pivot pin holes. All that's needed is to center drill, drill, and ream to size.

#35 With out removing the piece from the collet block after the previos step to drill the cross hole for the pivot pin, a slot was cut to proper depth using a 1/16" slitting saw.

#36 The picture below shows the valves finished, except for the raised burr I just noticed reviewing the picture in this post. Not a problem, I find little details that need attention and correct them (if I remember) before final assembly.

Some of the parts are in this build are a bit to small for me see without the aid of magnification. I suspect that at least some the older gent's (like me) on this forum avoid many, if not all of Elmer's plans due to their small size. I read that most of the plans were geared towards owners of smaller machines. Up sizing the plans has worked for me on a few previos builds.

"Sometimes I feel like I'm employed at a factory that produces hand made tooth picks." ;D

-MB