Newbie and the Crankshaft

[Foozer]

You have a interesting problem there. The fixture you have has the rotation axis on the shaft center-line obviously, and you need it to be on the crank-pin center-line (maybe). How close is your crank-pin to finished size.

Fixture at end of crank has a center drill location for the crank-pin incorporated. Crank-pin and shaft themselvesare at this stage still oversize (pin +0.063 o/s, shaft +0.063 o/s)

If you have the pin to size, I would get a layout line on the counterweight showing the 5/16" radius. If the pin is 5/8" in diameter for now, all the better. Looks like it's 5/8" by the photo, so maybe you saw this coming?

Knew turning the smaller dia would require some thinking, idea is within the crank-pin plan there is to be an offset of 0.010 x 0.625 to act as the rod side bearing surface. Rod big end 0.375w counter throw internal width 0.395. Ya something like that, so the plan is to mount the crank in the crank-pin jig location and work the inside counterweights to bring out the rod bearing surface (thrust bearing 0.625 dia) and bring the pin down to near finish size.

I would just use your same boring bar setup, but now you will need to rotate the crankshaft a little each pass and cut to the layout line or to just touch the pin if it's 5/8" diameter. A little indicator work later will get the shaft indexed in the fixture again.

Kevin

Its actually the crank that will rotate, but I think thats the idea. I can fab another jig (I think) that will attach to the current one allowing me to rotate the crank along it crank-pin axis.

It'll be a few days for this, cant forget the ol AA109 is real picky in how its used, especially the closer to finished size the item gets.

Thanks for the input, now to put it to use

 

[joeby]

That should get you there. Harder to say than to do.

Color it with a black magic maker when you're done, it will make it easy to file out the little scallops that will remain.

Kevin

 

[Foozer]

“Do what you can, with what you have, where you are.”
Theodore Roosevelt

Well now after some 45 hours its a getting closer too done. At one time I liked the saying , Takes 50% of your time to do 95% of a job and the other 50% for the last 5, Hmm beginning to find the truth in that.

So its down to the last tidbits to be chopped off.

Using existing jig (less movement from original cutting tool the better for me) a simple sort of indexing scheme developed, OK a QTR inch bolt with a pointy tip and a hunk of stock that engages some holes drilled into the circumference on the waste end of the crank. There is a slight problem with this scheme and the next time I try this I will correct the jig to rotate around the crank pin axis rather than the crank C/L itself.

I see why some cranks are built up from separate pieces, so far its straight. Will know in perhaps another 20 hours how this exercise turns out. Me and my Boat Anchor just enjoying another day in paradise.

 

[Tin Falcon]

WOW amazing what you are doing with the little Craftman 109 . ! have 2 of them that I have never really used I have a 7x 10 mini lathe and " south bend a mini mill and a sharper.You are doing a great job of using what you have to its fullest potential and beyond.
Tin

 

[Foozer]

“Do what you can, with what you have, where you are.”
Theodore Roosevelt


Now after some 50 hours into it this little exercise has about reached its end. Still need to dress the ends, yet will not do so until i conjure up a steady rest. Need one anyway so might as well make one. This little AA109 needs all the help it can get

Setup the crank to test its run out, put some little ball bearings on the ends and gave it a spin, well its got a 0.002 wobble in it. I can live with that.

Next tho its into the sandblast box to work the crank throws, give it a bit of the "cast" look and blast the sharp edges away.A bit of heat shrink and tape to protect the bearing surfaces and all will be good.

What did I learn?
Roughing down to size - leave enough material to support the crankpin turning

Do the finish work on the crank pin first.

Fab a space to insert into the journal space for support before working the shafts themselves.

MAKE SURE the flipping tailstock is lined up, could of been worse

If any journal work is to be done as I attempted e.g. turning the pin end down to a smaller dia than the throws, jig it up to rotate on the pin c/l. Going of the crank c/l just creates to many issues.

So one piece cranks can be done, I have never done it before and altho not perfectly straight it will be a usable part. I dont think a 2 thou wobble will be noticed for the gizmo I plan to use it in.

Next exercise. A flywheel with a taper lock bushing, actually 2 of them.

 

[deere_x475guy]

Very nice so far and I really like the look of taper bushings. I used them on my Siamese Twin in my avatar. One tip I would like to give you if you don't already know is to cut your tapers in the flywheel and then cut your tapers on the bushing W/O changing your taper set up. I made that mistake on one of mine and didn't quite get the taper the same. The second one I did like I just described to you and it came out perfect.

Best of luck and keep the pics coming.

Bob

 

[Foozer]

“Do what you can, with what you have, where you are.”
Theodore Roosevelt


Crankshaft is done. Had to make a steady rest ( thats a whole 'neither adventure) so I could trim the ends down. Did a bit of tailstock offset to taper the crank pin end down a bit

Sandblasted the throws (hides a lot of sin) gives it a nice contrast. A little work with 400 grit paper and some polish, call it good. Heck, the ball bearings even fit snugly. Now there is that hunk of brass just a waiting to give up whatever flywheel this newbie can find in it.

Next up Newbie and the Flywheel(s)

 

[rake60]

Beautiful craftsmanship Foozer! :bow:

Rick

 

[Foozer]

Beautiful craftsmanship Foozer! :bow:

Rick

Appreciate the comment, but its just a crankshaft. I just like the one piece flavors. You can see where the bearing fit is a little tight on the right hand shaft. Left the marks just outboard of the throw. A tad more with the 400 grit paper should ease the fit a bit.

Compared to what builds are shown here what I am doing is amateur stuff. Doing the flywheel(s) should be fun. Only got this ol AA109 lathe to work with so will have to get creative in its use. Got it tore down now for a cleaning and adjustment before I move on to the wheels. Little elbow grease and even stone axes and flint knives can a palace make.

 

[cfellows]

Turned out real nice, Foozer. Let's see, at minimum wage, I'd say you got about a $300 crankshaft there! Looks like it, too! Nice work.

Chuck

 

[Foozer]

Turned out real nice, Foozer. Let's see, at minimum wage, I'd say you got about a $300 crankshaft there! Looks like it, too! Nice work.

Chuck

A what you dont see.
Needed a steady rest to trim the ends. And so with hack saw and file this is what resulted. As shown the first crack at it didnt fit so well, flipped the stock 180, some carriage bolts, thread inserts and ball bearings resulted in a usable, say what? looking tool.

 

[Maryak]

Foozer,

One exceptional crankshaft. :bow: Lots of innovation in the way you made it. :bow:

I and I'm sure many others, are waiting to see what you do with the flywheels.

Best Regards
Bob

 

[steamer]

Wonderful!....I too owned a 109 as my first lathe

I made a lot of stuff with it, but I never made it dance like that!

It just goes to show.....it's not the machine, but the Machinist!

Very clever! Very Thorough, Understands the limitations, Works accordingly!

Well Done!

Dave