Building Elmers #44 Open Column Twin (Final pictures, and video)

[Metal Butcher]

To start off this building season I decided on this simple two cylinder. Its compact and about the same size as most of the previous engines I have built. The main point of interest is the valve location that allows it to control two cylinders reminiscent of a Stuart Sirus or Sun.

I) The cylinder block was band saw cut oversize from common aluminum bar stock. Using a fly cutter in the MD it was accurately machined to size indicated in the plans. Precision micrometers and square were used to verify its dimensions and squareness before proceeding.

2) Here's the MD and set up used to size the cylinder block. The photos show the mess left by one sizing operation. Subsequent photos will be "staged" to conceal this reality that we all face.

3)The cylinder block was first drilled to 1/2" and then brought to a finished dimension of .750 using a small boring head and bar. To accurately place all the bored, drilled, and taped holes scribed intersection locations were verified using the calibrated hand wheels on the MD. Drilled holes are taped using the chuck to accurately locate and center the hand- tapping operation. You can see a small diameter aluminum turning disc that I use to minimize tap breakage.

4) This last photo shows the finished cylinder block and pistons.The transfer ports at the top of the bore were done using a 1/8" end mill. The intake and exhaust openings on opposite sides of the block were tapped 10-40 for the 3/16" model pipe that will be used.

I'll post more parts and pics as the build progresses.

-MB

 

[4156df]

MB,
Great start & nice write-up. Looking forward to more of the same.
Dennis

 

[Twmaster]

Looking at all these projects being brought to life here is a wonderful thing.

That is some very nice looking work. I'll be watching.

 

[Metal Butcher]

5) I used 1/4" and 1/8" scrap aluminum plates to machine the base and table. After they were band saw cut oversize I used a 1/2" end mill to bring them to finished dimensions. Accurate sizing was important to assure properly centered openings and spacing on drilled holes. All the machine work preformed on these pieces was located after zeroing out the machine spindle on their edges. By using the the calibrated hand wheels on the MD accurate hole placement was archived. As an additional precaution I used scribed intersecting lines to verify the locations on the work piece.

6) The rectangular opening on the base was roughed out by eye using a center cutting 1/2" end mill. Using light climb cuts a 1/8" end mill was used to finish the opening.

7) The piston rod clearance holes in the table were roughed out by eye again using the 1/2" end mill. I used a scribed circle as a guide and stayed within 1/16."

8) Final sizing was accomplished with two passes of a small boring head. This was easier, faster, and neater that dealing with the chatter and other problems I encountered in the past using a drill on thin aluminum plate.

9) The twelve holes again, were scribed with intersecting lines and table moves were accomplished using the calibrated hand wheels on the MD to assure accurate placement.

10) The base holes were drilled using the same method. Note the four counter sunk holes that will be used to hold the bearing blocks from underneath the base plate.

11) With the machine work finished, all that's needed is a final planing (fileing) and blocking (sanding).

-MB

-MB

 

[cfellows]

Nice work you're doin' there MB. Thanks for progress report.

Chuck

 

[Deanofid]

Getting right on with it, MB. Quite a bit done for only a couple days work.
Looks like a fun build.

Dean

 

[IronHorse]

Nice build, should be a nice engine.

I like your mill, I wish my mini-mill had "calibrated Hand Wheels" ;D ;D ;D

 

[Metal Butcher]

12)The rails were cut from 3/8" square 6061 aluminum bar stock.The stepped areas were strait forward milling. The two clearance holes on both ends were drilled for #6 hold down screws. I decided to use columns that will be tapped from both ends eliminating the need to machine threaded shoulders.The six column screw holes were step drilled from underneath to accommodate and conceal the #4 cap screws that will mount the six columns to the base plate.

13) The valve plate was cut and milled to proper size from 1/8" brass plate.After precision lay out the three valve ports were milled out. The two holes near the front were clearance drilled for #2 screws that will attach the rocker pivot from underneath. Latter it will be soldered prior to being slotted along with the valve plate.

14) With all of the milling and drilling on the valve plate finished, the rocker pivot was machined and test fitted.

15) With the major work completed, all of the parts were block sanded on #220 wet/dry sand paper. The rocker pivot was tinned, screwed into position, and sweat soldered on while tightening its screws. To conceal the threaded holes used to attach it, I tapped the pivot block instead of the valve plate.The valve plate was previously clearance drilled for these screws. The exposed threaded holes bothered me a bit, so I changed the screw head locations. :

16) This final picture shows the rocker pivot slot milled clear through the rocker pivot and the specified 3/8" into the valve plate.

More to come... Lots more.

-MB

 

[zeeprogrammer]

Very nice! Great thread. I'm enjoying the detail too!
Thanks.

 

[Metal Butcher]

17) Hi all. I didn't have a chance to spend any time in the shop yesterday, but today I managed about 5 hrs and made a few more pieces.
After sizing a block of brass that will become the steam chest, the cavity for the slide valve was plunge milled with a 1/2" center cutting end mill, and finished with a 1/8" end mill. The photo shows it being milled down to its proper specified height. I decided to make the steam chest as a build-up of three parts that will be soldered together, or assembled with Loc-tite.

18) The valve was made from a longer piece of brass milled to the finished width and height. This allowed it to be held in securely the vise. After milling out the 1/4' x 1/4" x .032 transfer pocket the bar was flipped over 180 degrees, and the two 1/8" channels accurately located and cut to depth prior to parting off.

19) The bearing blocks were milled to size from scrap aluminum and profiled to suit with a corner rounding end mill. The photo shows them being drilled and reamed for slithered bronze bushings (Oil-Lite's).

20) The bottom of the bearing blocks were drilled and tapped 4-40. They will be bolted from underneath the base plate using counter sunk flat head screws.

21) The bushings will be pressed into the bearing blocks after they are cut to the proper width.

22) The bearing blocks were test fitted to the base.
Amazing! They fit perfectly! The careful layout, drilling and tapping, of the base and bearing blocks just paid off.

23) This last photo in this post shows six other pieces started today.
Top row from left to right: slide and steam chest.
Bottom row; guide, valve, nut (for valve rod), steam chest cover.

Not bad for a short day's work.

-MB

 

[mklotz]

I hope Zee takes note of how you made the valve.

That's exactly the technique I recommended to him in his thread on building his mill engine.

 

[Metal Butcher]

I hope Zee takes note of how you made the valve.

That's exactly the technique I recommended to him in his thread on building his mill engine.

Thanks Marv. I think it's a better way to make this small part, and there is also the bonus of extra material already sized, just in case.

The few I made in the past were fully sized prior to milling the transfer port and cross slots on the opposite side. Not much to hold on to that way, not to mention how easily the part was re-sized by the vises grip-of-death.

I cut off the valve with the same 1/8" end mill based on calibrated hand wheel moves. Worked like a charm and with a lot less stress. :big:

-MB

 

[zeeprogrammer]

I have certainly taken notice. ;D

But just to be clear about what Marv said...it's not that I didn't listen to him. The recommendation came after my attempt to follow the instructions that came with the kit.

Sorry to be off-topic. More sorry you hadn't done this before my own valve work. Then I'd have known a better method than presented in the instructions...and Marv wouldn't have had another opportunity to ding the instructions. :big:

Great thread MB. Thanks for the detail.

 

[Brian Rupnow]

Another pretty and well detailed thread.--Do you have a picture of what the finished engine is supposed to look like?----Brian

 

[Metal Butcher]

Another pretty and well detailed thread.--Do you have a picture of what the finished engine is supposed to look like?----Brian

Hi Brian. With me on the project you never know what it's gonna look like! Nor do I!: :big:

Seriously tho, here's a link to exactly what one looks like if one follows the plans exactly. Pictures in my previous thread of the finished engine were provided by Marv (mklotz). As you will see he built a absolutely beautiful example.

http://www.homemodelenginemachinist.com/index.php?topic=6522.0

-MB

 

[Metal Butcher]

24) I finished up the started parts shown in the last picture of my last post, picture # 23. The two guides on the steam chest were machined separately and installed as a light press fit along with the use of Loc-Tite. The six columns were cut to length and tapped 4-40 from both ends.

25) The picture below shows a piece of scrap clamped in the MD and faced flat with a fly cutter. This is the first step I took to make my crank shaft. A head scratching, but interesting approach I have used in the past to fabricate a crank.

26) After rough centering the MD quill on the fly cut scrap, the hand wheels were zeroed out. The I drilled and tapped 1/4-20 for a bolt that goes through the center hole reamed on all three crank discs. Its important that the bolt fits the crank discs tight or the accuracy of the crank will suffer. The spindle is offset .375" both fore and aft of center to drill two holes in the center disc. The two outside discs need only one hole each, and were stacked and drilled/reamed as one piece.

27) The three pieces of shafting were cut to length from precision ground S.S..
Each joint was assembled individually (See Elmer's text) to keep things from going haywire. Trying to accurately space three discs on three shafts while the Loc-Tite is setting up would be difficult at best!

28) The semi finished crank was mounted on the base plate and checked for run out on it's outer surfaces. The largest deviation (high spot) found was .002. This is very acceptable to me since these are not not running surfaces.

After a 24 hour set up (Loc-Tite) time the shafts will be drilled and pinned. Afterward the center shaft on the crank throw ends will be removes using a hack saw.

I cut the discs from 12L14 steel. I had the correct size bar on hand since last year when I ordered some to try out. This was the first time I machined this stuff. It's great, I like it a lot! It machines like a cross between cast iron and brass. The 1018 I have used in the past is somewhat disappointing by comparison. Unfortunately my supplier only carries round bars.

Does any one know of a source for 12L14 in flat plate, square, or rectangular bars?

After a little clean up in the shop, its break time.

-MB

 

[Tin Falcon]

Does any one know of a source for 12L14 in flat plate, square, or rectangular bars?

square stock from 1/4 to 2 1/2 inch here
http://www.mcmaster.com/#12l14-steel-products/=4ejr4l
Tin

 

[Twmaster]

Speedy Metals also has 12L14 in square. I've bought from them and they are good to deal with.

http://www.speedymetals.com/c-8249-12l14.aspx

 

[Deanofid]

The crank is looking good, MB.

I don't think 12L is made in shapes that won't go through a chuck. It's mainly a product for screw machines and auto chuckers, and just turned out to be great for us home shop guys, too. I could be wrong, but I've never seen it in flat bar of any size. It does come in hex in lots of sizes though. Great stuff for making your own cap screws and nuts.

Dean

 

[Metal Butcher]

Tin Falcon and Twmaster, thanks for providing two good sources for square bar 12L14.

Deanofid, I agree it's the good stuff. With the shapes available a lot of the engine parts like cylinders, pistons, heads, crank cases, crank discs, fly wheels, etc could be made from this material.

Reasonably priced too.

-MB