Horizontal Double acting Twin Self starter

[Brian Rupnow]

We're getting to the scary part now!!!! I've cut the main crankshaft out in the area where the connecting rod journals are. That little jig I made from the block of aluminum with 2 holes in it has proven to be an excellent way of holding onto this thing while filing it. now we are heading for the lathe. I guess this is where I get to learn turning with a cut off tool. Thats the only tool I have thin enough to fit in and machine the silver solder off the journals with.

 

[Brian Rupnow]

The batteries are dieing in my digital camera. This picture shows the reason that I left the long tail on the peices of crankshaft that are the connecting rod journals. I took a scrap peice of aluminum rod and drilled and reamed a hole in in 2" deep. Thats how I hold things to turn the connecting rod journals on the lathe.

 

[seagar]

I am really enjoying this ,thank you very much for sharing .

Ian.

 

[Brian Rupnow]

Here we are set up in the lathe. The aluminum adapter is in the chuck, with one leg of a connecting rod journal positioned in it. The main crankshaft is acting as a lathe dog, fitted in between the chuck jaws. I put a point on a long peice of brass and held it in the tailstock mounted chuck, just as a safety to keep things from moving parallel to the lathe bed--remember, I'm not actually gripping the crankshaft. i had to put a point on the brass and a small centermark in the crank assembly at point of contact, otherwise the brass rod wanted to "orbit" as the crankshaft turned.--And Oh Yea--You can see my parting off tool being used to machine with. all my real cutting tools are too wide to fit.

 

[Brian Rupnow]

First journal machined----scary stuff--Held my breath the whole time!!!

 

[Brian Rupnow]

Both connecting rod journals machined up fine. I then cut the long "tails" off them that had previously fit into the aluminum adapter while they were being machined. I chucked one end of the crankshaft up in the chuck, but I was scared of bending things when I started to machine the center journal. Then inspiration struck!! I had an MT2 "blank" that I had bought for a different project and never used, so I drilled and reamed a 1/4" hole in the end of it, filled it with grease, put it in the tailstock, and slid it over the "free" end of the crankshaft to act as an outboard support while I machined the center journal.

 

[Brian Rupnow]

So there we are fellows. If a newbee machinist/old fart like me can make a built up crankshaft, then anybody can!!

 

[Brian Rupnow]

CRANKSHAFT DETAIL

 

[Brian Rupnow]

Maybe I'll try these next. So far I've built 3 steam engines, and I took the cowards way out on each one as far as flywheels go.--(Made them as round plates with holes for decorations.) Now I think its time to get really bold, break out the rotary table, and try something fancy. I am fully aware that some of the people on this forum who I consider "Real Machinists" prefer their flywheels with tapered spokes. I think that it will be a personal milestone if I can make a flywheel with spokes, period.!!! Someday when I,m feeling REALLY BOLD I'll try the tapered spoke thing. ---EDIT EDIT EDIT--I have had to make a couple of changes to the flywheel drawing. Since the 2 flywheels have spokes, and I (at least) would like to keep the spokes lined up, and because I want to balance the rotating crankshaft assembly, The flywheel hub design changes to an offset hub as shown, and there are 3 lightening holes added to the rim as shown

 

[CrewCab]

Blimey Brian ......... you don't 'ang about do you ....... looking pretty good to me, well done with the crankshaft. As for flywheels .......... tapered spokes shouldn't be much more complicated than straight ones .......... the maths is straightforward for the co-ordinates, though I suspect it would be much easier with a dro on the mill ........... do you have one? .............. OK CNC would be easier still but where's the fun in that ;D

Enjoying this thread very much, thanks for taking the time to document everything ............. your making me think as well, ..... earlier I looked at your aluminium jig for turning in the lathe and try as I might I couldn't figure out how you were going to drive it ........ after about an hour of it niggling away at the back of my mind I finally figured it out ........... the other leg acted as a dog ........... I was very chuffed to go back to your thread and find out I was right ;D

Keep it coming please Brian ............. I suspect there are many out there hanging on every post 8)

CC

 

[Brian Rupnow]

Crewcab--No, I don't have DRO s on my mill. Sure wish I did thought.

 

[CrewCab]

What the heck, straight spokes are fine by me 8)

CC

 

[wareagle]

Brian, this is looking great! Congrats on your crankshaft! :bow:

By the way, don't worry about feeling like your not a machinist... You really are but just don't know it yet. Each and everyone on this board started from ground zero. The paths and current places for each are different, but the one thing in common is we all enjoy widdling metal into parts! Stay at it! You're doing great!

Besides, I learn something new everytime I go into the shop. I am sure many others here do as well!3

 

[Cedge]

Brian
Excellent work and a great show of how working intuitively will get you where you want to go. I have to admit you had me holding my breath too. I'd have been super gluing spacers between the journal blocks to prevent the chance of collapse when under pressure from the lathe.

Several photos are floating on the board where the dreaded AWWW $*%# moment jumped up a the worst possible time. And yeah... I too have one of those fancy looking pretzel cranks hiding in one my scrap spare metals boxes.... somewhere ...LOL

Don't let the flywheel thing spook you. slow down and think your way through it. The tapers are no high step for a high stepper. The curved spokes... well... let's just say they scared the bejeezes out of me too, until I jumped in and drove right on through... at least on the second attempt, that is....(grin)

Steve

 

[Brian Rupnow]

I just about fell down dead this morning when I called my local metal supplier guy and inquired abut the price of 2" of 4" diameter brass. --Holy cow!!! $80--- So I drove down and found a "cut off" peice 10" long in the shorts rack. I whined and begged a little, and he decided to let me take the part home and cut it myself to avoid any cutting charges, and to return the chunk left over. That way he said, "Take 2 1/2" so you will be sure and have enough, return whats left over, and bring me $60 cash. So---Thats my big old, 40 year old, home made power hacksaw chewing away out in my garage.

 

[mklotz]

Brian,

If you've never done a spoked flywheel before, you might want to make a practice one from aluminum (or even, shudder, wood) before risking $60 of brass. Just a thought.

 

[Brian Rupnow]

Brian,

If you've never done a spoked flywheel before, you might want to make a practice one from aluminum (or even, shudder, wood) before risking $60 of brass. Just a thought.

Marv--I'm going to do this !Slowly, slowly, creepy mousie"!! I'n not worried about the lathe-work part of the build. For the spokes, I will lay it out with marking die first, and then be darn sure that my mill and rotary table settings are in 100% agreement with my layout work before actually cutting brass.

 

[BobWarfield]

Lots of ways to skin the flywheel cat. While you've already bought your brass blank and no doubt intend to continue in that vein, I thought I would post a link to The Engineman's built up flywheel as an alternative for others:

http://modelengines.info/goldeng/const/flywheel.html

Cheers,

BW

 

[GailInNM]

Brian,
With the cost of brass the way it is today, it may be time for you to step up your machining experience on your next project. Cast iron and 12L14 steel are both easy to machine. Cast iron is messy, but cheap. Both take a little bit more work to polish. But cast iron is about 20 percent of the cost of brass and 12L14 is about 25 percent the cost of brass.
Gail in NM,USA

 

[Brian Rupnow]

Damn--I just lost 20 minutes of typing when I went to post.--It gave me a message saying "my uploader space is full"!!!