Building #52, Elmers RVTW

[Metal Butcher]

With the completion of my double build of Elmer's #14 its time to start another. The model I picked is Elmer's #52 Reversible Vertical Twin Wobbler (RVTW). I down loaded the plans and took a quick look at the materials on hand. Looks like I have enough scrap for the project. I can slice up some brass and aluminum pepperonis to make square if need be. This makes today my official starting date.

"The Cylinders are double acting and self starting". Music to my ears. Could turn out to be another one or two pounder!

Tomorrow I'll clean up the shop a bit, and start gathering tools and materials need to take my first cuts. But first I need to vacuum up the house a bit. Seems that some aluminum chips grew tiny wings and migrated out side there "allowed territory" to be noticed by "Honey."My first picture/post should be in a day or two.

Feel free to post a picture, if your done... or grab a hunk of metal, and join in with the fun! That sorta rhymes :big:

Plans; http://groups.yahoo.com/group/Elmers_Engines_4/files/

-MB

 

[lathe nut]

Metal Butcher, I am excit me, you start machining and I start copy and paste, going to have me a place soon where I can machine in the heat in the winter and the cool in the summer, my wife is going to let me have the storage room that is next to our carport with the house all under one roof, its 6X24 and she got the 3,200 square foot house, she said that is a good deal for me, Yes Dear, cleaning it out and doing a paint job, going to be nice to be inside, Lathe Nut

 

[cfellows]

Man, you are on a roll! Are you going to work your way through all of em? :big:

Chuck

 

[Metal Butcher]

Metal Butcher, I am excit me, you start machining and I start copy and paste, going to have me a place soon where I can machine in the heat in the winter and the cool in the summer, my wife is going to let me have the storage room that is next to our carport with the house all under one roof, its 6X24 and she got the 3,200 square foot house, she said that is a good deal for me, Yes Dear, cleaning it out and doing a paint job, going to be nice to be inside, Lathe Nut

Sounds like you couldn't ask for a better trade, as long as you can occasionally visit the other half of the house.

6x24 you say! That will be a very, very big shop!

If you can install a phone, couch, refrigerator, and toilet you will have more available shop time! Sort of a home away from home!

Make an agreement that every one cleans their own half! ( I got talked into cleaning outside my "territory" today! :big:

-MB

 

[Metal Butcher]

Man, you are on a roll! Are you going to work your way through all of em? :big:

Chuck

Hi Chuck.

I don't have any set plans. Remember me building two of your designs in the winter last year.

I still would like to build a few more of Elmer's Engines, but I can switch direction on a whim.

There are so many models out there, and on this forum, that I doubt any one could build them all in a short time.

But I'll keep trying! :big:

 

[zeeprogrammer]

Looking forward to the build MB.

Make an agreement that every one cleans their own half! ( I got talked into cleaning outside my "territory" today!

'Territory'? You lucky. I've been told I have a rental...with no lease.

 

[Metal Butcher]

#1 To start off my project I marked out a 1/2" 6061 aluminum plate and band saw cut the oversize rough blanks. I would have preferred using a harder material for the column but my choices are limited by my current supply on hand. In many of his plans Elmer suggests a "fixture grade" of aluminum, and I suspect that 6061 does not qualify.

#2 After roughing out the pieces their four edges were sized and squared using an end mill.

#3 All the pieces were planed flat on both sides using a fly cutter. In the picture below the reason for this step can be clearly seen. After a .002" cut the areas indicated with a marker were not even touched. It took another .002 cut to achieve a flat surface. All of the plates made were planed level on both sides. This is a critical step that's needed to assure that all subsequent parts bolt together with a high degree of precision needed for smooth assembly and running.

#4 The picture below shows the major structural components of the build ready for the next machining steps. The two small blocks in the upper right corner will become the bearing blocks that support the crank shaft.

#5 The cylinders will be cut from the 1" x 3/4" brass rectangle. I changed my mind and will not be using the 3/4' X 3/4" brass bar shown below. The upper and lower cylinder heads will be made as a build-up of lathe turned pieces assembled to a 3/4" x 3/4" x 1/8" base plate. The lower heads will need to be very precise or the piston will bind. It will be interesting to see if I can make this ideal work.

#6 Here I'm sizing the block of brass that will become the two cylinders. These will also be made as a build-up of the cylinders and separate 1/4" pivots. The blocks were sized to 1- 5/16" long 3/4" wide, and .7813 deep.(not shown)

#7 I cut the cylinder heads 3/4" + .030" long, from 3/4" wide by 1/8" thick brass rectangle scrap. In the picture below the cut ends are being milled down to 3/4" in length.

#8 As you can see there will be a lot of filing to bring these pieces up to a presentable state. I made two extra blanks just in case, and due to the precisely located 1/2" hole they will need to become the basis of my build up attempt. Again, it will be interesting to see if my idea will work.

#9 The picture below is not necessarily related to this build. It shows a drilling fixture I made for 3/16" bronze pipe fittings. When I went to assemble my last build (Elmer's #14) I found out I didn't have a "tee" that was needed and the few elbows on hand were not drilled and tapped. I finished the fittings using my old unreliable eye-ball method along with the wrong fitting jus as a temporary way to finish my build. Then it dawned on me that I never machined up the fixture that was recommended by bearcar1 in answer to a thread I post quite a while back.

Thank you bearcar! :bow:
For posting the help that I needed to make a fixture to machine 3/16" elbows, tee's, crosses and unions. The project slipped my mind till last Saturday, and today I made the fixture just prior to this post. My fixture is made from rectangular stock for use in the mill. Its a great idea for a fixture, and it should work perfectly.

http://www.homemodelenginemachinist.com/index.php?topic=4479.0

-MB

 

[Metal Butcher]

#10 To finish up the milling on the base I started by roughing out the crank shaft pocket with a 1/2" end mill. This first operation was eye balled up to about .030 inside the scribed lines.

#11 Using a 1/4" end mill the pocket was finished using the calibrated hand wheels to move the milling table to calculated co-ordinates. The accuracy of the openings size came out much better than previos work done using an eye-ball method.

#12 Milling out the four 45 degree clearance cut outs for the piston rods was very easy. I remembered the jig I made to simplify milling identical corners on the bearing blocks of a previos build. After I using an edge finder to zero out on the front edge of the 'base', I exchanged it for a 3/8" end mill and moved it the distance shown on the plan. After setting the correct cutter height and locking the quill, It was a simple cut-flip-cut to finish all four openings.

#13 To cut the profiles on two sides of the base I set the end mill at the proper height and moved it in the width specified in the plan. It was a simple matter of cut-rotate-cut. To get a nice finish using only one cut I went slow and used aluminum cutting fluid.

#14 The picture below shows the 'base' with all the milling finished. After I drill all the necessary holes, and after a little file and sandpaper work, it will be ready for paint or polish.

#15 The 'retainer' will be made as a build up. I will add the bosses needed to hold the cylinder retaining screw, spring, and ball. Below the picture shows it milled out and ready for the next step.

#16 The final milling step was to add a little detail to the plain rectangular look the 'retainer'. I used a corner rounding end mill to add a radius on its upper and lower sides. The front and back will be left flat for the addition of the bosses. In the plans the 'retainer' is made as one piece by turning it up in the lathe, which gave its sides a large radius.

-MB

 

[zeeprogrammer]

Looking great. Finally had a chance to find a picture of the engine. That's going to be nice.

'aluminum cutting fluid'...I hadn't heard that mentioned before...what's the brand name so I can learn about it?

Thanks

 

[ksouers]

Holy Cow, MB! You're really moving right along on this.

 

[Deanofid]

Going along well, MB. That rounding bit makes a nice job of the corners.
I see your milling machine is "that color" too! You're dedicated!
; )


Zee, "aluminum cutting fluid"; Don't know what MB uses, but one of the few things that WD-40 is actually good for, IMO. On some of the gummy types, it helps keep the end mill flutes from plugging. Tap Magic works pretty well, but WD seems to do quite well.

 

[tel]

Looking great. Finally had a chance to find a picture of the engine. That's going to be nice.

'aluminum cutting fluid'...I hadn't heard that mentioned before...what's the brand name so I can learn about it?

Thanks

Yeah, WD40 works, or just plain old kerosene (lamp oil) (paraffin to you Poms)

 

[Metal Butcher]

Looking great. Finally had a chance to find a picture of the engine. That's going to be nice.

'aluminum cutting fluid'...I hadn't heard that mentioned before...what's the brand name so I can learn about it?

Thanks

Hi Zee. The aluminum cutting fluid I used is called Tapmatic dual action #2 cutting fluid for aluminum. Its made by Tapmatic corp. It does work and helps to get a smoother finish on aluminum. It may have been replaced with a safer formula, but not as good from what I hear.

When I tap aluminum I use Tap Magic tapping (cutting) fluid. It made by Steco Corp. Its no longer available so I treat my supply like gold, and use it one small drop at a time when I tap small blind holes in aluminum.

Here's a link that may have answers to any questions you may have.

http://www.lpslabs.com/product_pg/cuttingfluids_pg/LPS_CuttingFluid.html

-MB

 

[zeeprogrammer]

Thanks MB. I've heard of Tap Magic but hadn't gone looking. I didn't know there were various types. Thanks again.

 

[Deanofid]

MB, and Zee, Tap Magic is still made by the same company. They changed it slightly about 10-12 years ago to get rid of the ozone depleting chem it contained. We used it by the gallon at a shop where I worked during the time they made the change. There was a difference in the new formulation, but it didn't change our production or tool life that I could tell, so I kept using it, and still do today. It's here;

http://www.tapmagic.com/

http://www.use-enco.com/CGI/INSRIT?PMAKA=505-2007&PMPXNO=940681&PARTPG=INLMK32

http://www.use-enco.com/CGI/INSRIT?PMAKA=505-2011&PMPXNO=940682&PARTPG=INLMK32

Either of the two in the Enco links seem to work the same, for my use, at least.

Dean

 

[Metal Butcher]

Dean, Zee, and every body else, I remember when the formula change came. In that era I was adding tools and would visit two machine shop suppliers on a weekly basis. I got to talk to a lot of customers and sales people on a regular basis. The general consensus at that time was that the 'new' Tap Magic for 'aluminum' fell short in performance, and as a result sales plummeted to the point were they stopped carrying Tap Magic for 'Aluminum' altogether. I don't think that Enco carries it to this day. They carry Tap magic 'cutting', Tap Magic 'Pro', but no Tap Magic 'for aluminum'. Quite a while back I ran out of the 'old' formula for aluminum. I tried the 'new' Tap Magic for 'aluminum' and didn't like it at all compared to the original formula. Afterward I started using the 'old' formulation of Tapmatic #2 cutting fluid or aluminum as a replacement. Recently I got an unopened can of the 'original' formula of Tap Magic for 'Aluminum' and I just love the way it works. I mentioned in my previos post that its no longer available, meaning the 'old original' formula. The old Tap Magic is much better than The 'old' formula Tapmatic #2 for aluminum, which was better than the 'new' Tap Magic for Aluminum. I should mention that I have not tried the regular 'Tap Magic', or the 'Tap Magic Pro' and assume that they are not specifically marketed for use on aluminum, but may work well in their targeted area of general use.

The Mention of a "cutting fluid for Aluminum" in my previos 'build post' was a calculated move to bring to light that the use of cutting fluids can and does make a difference in finish quality. Granted, we all have our own favorite products.

Discussing which product or brand is better, is like discussing which brand or type of 'alcohol delivery system' is better, especially if we already had a few! Every one has a favorite, opinions vary and change from year to year, sometimes from drink to drink. The only constant and recurring event is the 'sought after' result of over-consumption. ;D

However, when we are in the shop, and using cutting fluid for its intended purpose, in most cases just a 'drop' will do.

-MB

 

[Metal Butcher]

#17 For today's build post I made the drill jig. They are a very handy and accurate way of locating the port holes on the cylinders and face of the column.

#18 Using a stop block set up in the mill vise, a 5/8" recess ('under cut') was milled .020 deep on the pivot face side of each cylinder. On the opposite side I milled the 'dimple' .020 deep using a 3/16 ball end mill. Elmer specified .010 for the 'under cut' and no specification for the ball 'dimple'.

#19 Since I'm making the cylinders as a build-up, 1/4" pivot pins were needed and cut to length. The cylinders were drilled and reamed to a depth that left the pivot pins 7/32" proud of the cylinders face. After fluxing, the pins were pushed in and popped right back out! So, I drilled holes down the center of where the piston bores will be drilled to meet the pivot pin bore. This passage will release the trapped air, and any build up of pressure created during the soldering process.

#20 After the cylinders cooled down they were drilled and reamed for the 1/2" bore.

#21 To make the lower cylinder 'heads' a build-up I drilled and reamed them 3/8" to match the diameter of the boss that will be tapped for the 'packnut'. With the mill all set up for the holes I decided to also drill the upper 'heads' for an added decorative boss.

#22 Below is a picture of how the upper 'heads' will look. The decorative 'caps' are a light press fit. During final assembly loc-tite will be used to assure a more permanent and air tight fit.

#23 To make the 'boss' for the lower 'head' assembly's, the packing nuts were turned up from 1/4" brass hex stock and threaded 1/4-20. I did not drill and ream the thru 1/8" hole for the piston rod. After turning up and tapping the 3/8" stock for the lower 'boss', I put some graphite packing string into the pack nut hole and tightened up the nut with the addition of low strength blue loc-tite. After a curing period the 1/8" hole for the piston rod was drilled and reamed thru both parts, and then cut off using a parting tool.

#24 The picture below shows one lower 'head' assembly finished and pressed together temporarily.

#25 All of the upper and lower cylinder 'head' bolt holes were drilled and tapped for 2-56 screws. Sometimes this part becomes a little bit repetitious and leads to boredom. I fight the tendency to rush this process, which can lead to tap breakage.

#26 Below is the final picture in this post. I drilled and tapped the pistons for the specified 5-40 thread, and then counter bored them .125" by .125" deep using a reamer. Before completely parting off the pistons I shut down the lathe, backed out the parting tool, and hand polished off the corner burrs with 1200 grit sand paper. The pistons fit very well, and are between .0005 and .0007 smaller than the cylinder bores.

Did someone say, "break time!" ;D

-MB

 

[Metal Butcher]

#27 To make the piston rod ends, 1/4" thick brass stock was sized to height for both halves of the ends using an end mill. The length of the stock was long enough to make duplicate pieces.

#28 I squared one end first, and then scribed a line for over size cut off using the band saw. The saw cut end will be milled square later, and to exact length along with the other three halves that will make up the piston rod ends.

#29 After cutting out the two corners on the larger halve of the piston rod ends with an end mill, all the holes were drilled for screw clearance or tapping. The 1/8" piston rod hole, and the 1/4" crank pin hole were finished by reaming.

#30 The 'bearings' that were milled to dimension in an earlier post were drilled and tapped for the 4-40 screws that will hold them to the 'base'.

#31 The picture below shows the profile's being milled with a 1/2" corner rounding end mill. I was planing (plan A) on just a slight round-over on the corners, but I didn't like the way they looked. I went with more of a profile (plan B) that ended cutting into the tapped hold down holes. I have to either remake the 'bearing' block and drill to shallower depth, or fill in the exposed holes.

#32 Since aluminum 'bearing' blocks would wear out quickly, I drilled and reamed them for 3/8" diameter (Enco #325-7480) slithered bronze bushings (Oilites). They are also 3/8" long, which is greater than the 5/16" width of the bearing' blocks. They will be pressed in and adjusted to eliminate the "thin spacer" or "thin washer" that Elmer specifies in many of his plans. I use over length bushings habitually on most of my builds since I don't have any of these "thin spacers," whatever that may be.

Has anyone started to build one of these?

-MB

 

[Metal Butcher]

#33 For today's post I built the crankshaft. The first step was to turn down stock that the three crank disc's would be cut from. I chose aluminum since a good supply of 1-1/2" round bar stock is on hand. I chucked it up in the lathe and center drilled for a tail stock live center due to its length. After machining the O.D. I drilled and reamed the central 1/4" hole all the way through and faced the end. I removed it from the chuck and cut off the larger 1-1/32 disc in the band saw. After returning the stock to the lathe the two smaller disc's were faced and then cut off with a parting tool. All three discs are faced on one side and will be faced from the other side to exact length after the crank pin holes are drilled.

The reason that I removed the stock from the chuck, and cut off the longer piece first, and in the band saw, was that I felt it was sticking out of chuck to far for parting off safely. I marked it first so that it could be returned to its exact position. I checked it for run- out with my dial indicator before proceeding with the facing and cut- off of the smaller discs.

#34 To accurately drill the crank pin holes through all three discs, a simple holding fixture would do the trick. After clamping a scrap block in the mill's vice, I faced it flat to insure that its face would be perpendicular to the mill's spindle axis. With the hand wheels zeroed out I drilled and reamed a 1/4" through hole. This will allow the disc's to be individually bolted "faced side" down to drill and ream all three disc's. After shifting the tables X axis .375" both thinner disc's were drilled and reamed. The thicker center disc was drilled and reamed last to insure accuracy. After its first hole was drilled and reamed, the table was shifted back to zero on the X axis, and then shifted .375" on the Y axis to drill its second hole in one set up. I used a precision .250" rod threaded on both end to accurately locate and hold down the work pieces during the drilling and reaming operations. The 90 degree offset on the crank throw has me scratching my head. I keep thinking that maybe I should have changed it to 180. Any one have any thoughts on this?

I guess that a four jaw chuck, along with a proper lay out of the hole locations would also do the trick, if I had one.

#35 The picture below shows the crank pin holes being drilled and reamed to the finished size. Afterward they were returned to the lathe for final facing and sizing.

#36 To assemble the crank I used a different sequence than the one that Elmer suggests. For step one I installed the main shaft into the larger center disc with Loc-tite and let it cure. In step two I added one out side disc and Loc-tited it to the center shaft only, and used the short crank pin for line up only, while spacing it away from the center disc with space blocks.

#37 After the Loc-tite cured on the first out side disc, the same procedure was followed on the second disc. In the picture below you can see that the crank pin is not in place an can be moved about freely while the second disc sets up. After all three discs cured and became one with the center shaft, the two crank pins were removed and installed with Loc-tite. The white smudge in the picture below is a piece of paper towel used to absorb excess Loc-tite on the center shaft. I didn't want my space blocks to become a permanent part of my crank shaft assembly. ;D

#38 The final but scary step is to hack saw out the center shaft between the crank throw webs. Its a good idea to protect the crank pins with several layers of tape or whatever is deemed appropriate during the sawing. On my first attempt of this type of crank shaft, the saw broke through and landed on the crank pin creating a unwanted cut.

I offset the crank to allow for a possible 1/2" wide flywheel on one side, while reducing the other side to a 1/8" protrusion out side of the bearing. With a light aluminum crank I might want to add a fly wheel. In the plan the shaft is centered and the protrusion on two sides seems a bit small for the addition of any thing other than a thin pulley.

After a little bit of filling to clean up the saw cut ends, the crank is masked and ready for paint.

Did you notice that I left out the expansion pins? I'm getting a little brave! :big:

-MB

 

[lathe nut]

Nice work, thanks for the pictures and description, Lathe Nut