Newbie and the Crankshaft

[Foozer]

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

I see a lot of post and info by those that know what they are doing. Me thinks it’s a bit intimidating for those like me, recently retired and have chosen the pleasant “Thump Thump” sound machining metal makes to occupy time away from the honey-do list. Perhaps some deeply buried bizarre desire to climb back into the womb, but, be that as it may, I’m not beyond taking a trip without a road map. I’ll just figure it as I go.

So as to the “What to build next” choices always drifting to beyond my abilities I’m thinking “Try and make a Crankshaft just for the heck of it” should occupy my mind for a while. So shall see if I tease out the crank hidden in the stock

This plan focuses for me the task of cutting out a crankshaft with nothing more than the little old 109. Don’t have a mill and the drill press is, well, not so good at drilling holes where I want them. First on the agenda is turning down to rough dimension the crankshaft blank, or wishful thinking, try and hack out of stock a crank as depicted in the drawing.

Now I need to make the jigs to hold the crank for the turning of the throw. I turned up some small chunks of stock in the lathe to get em as identical as my skill level allows. Heeding the advise of kf2qd

make one side of the fixtures the same distance from the centerline of the 2 holes so you can lay it on a surface plate and make sure everything is parallel before you put it in the lathe - other wise you might have ever so light an angle between the throw and the shaft.

the need for an accurate jig will be required later on. Problem is when a jig has to be made to make a jig.

Made a little holding fixture that mounts to the tool post, gave the surface a light fly cut to square it up with the chuck and located the blanks that will be the holders for the crank. Only method I could devise to ensure some accuracy in the placement of the shaft and throw center lines was to use the DI’s on the lathe. Kind’a learning as I go, will it work? Time will tell.

Next was the actual drilling of the 2 holes, first a ½ inch thru hole, (drilled a ¼ pilot first, then one slightly undersize, and finally full size). Moved the slide 0.375 and using a center drill, popped the second hole for the lathe center (which will be the crank rod journal). As I attached some tool stock to the holding fixture (a dab of Loctite) locating the second jig was just a matter of drop in and clamp.

Well after some 12 hours so far I have this in hand.

The flat on long side of fixture is equal in distance from the crank blank by a tad under 0.001. as checked with the DI. These fixtures are doubly attached, one set screw each on the short end and the long end which will hold the driven pin was drilled and tapped thru into the shaft itself. A short set screw engages both the jig and shaft. It should hold position throughout my further “what nows” to whittle the crank out of the hunk of I don’t know what kind of steel it is, I just found a 12 foot hunk of it laying around.

After another 12 or so hours of guess work I’ll show and tell again

 

[Kermit]

I can't see it


Where's the newbie part?




;D

 

[joeby]

As it is with most anything, there are 101 ways to do it. It looks like you have a good start, and realizing that you have one of the "not the most rigid machines", I think the next item to be handled would be to remove as much material as possible on the throw. How you accomplish this doesn't matter; hacksaw, file, cutoff wheel, etc.. Having done a few crankshafts from the solid, and also being familiar with the 109, l think your lathe will appreciate it.

The first thing on the list for machining, then, would be the throw so the oversize of the mains will help keep things together during the interrupted cut. Once the throw and the inner surfaces of the counterweights are done, you'll want to make yourself a spacer to put between the counterweights directly in-line with the mains. I've soft-soldered blocks in there, made bolt-in spacers, whatever works so that you prevent the shaft from flexing.

I haven't tried using the fixtures to offset the throw, looks like it should be put on my to-do list though. I've always just center-drilled the ends of the shaft; but being able to set it back up in the same fixtures later would have its advantages.

Kevin

 

[steamer]

I started with a AA109....Its tougher to do what you've done than you make it look!

Your doing a great job...keep at it!

Dave

 

[crankshafter]

As it is with most anything, there are 101 ways to do it. It looks like you have a good start, and realizing that you have one of the "not the most rigid machines", I think the next item to be handled would be to remove as much material as possible on the throw. How you accomplish this doesn't matter; hacksaw, file, cutoff wheel, etc.. Having done a few crankshafts from the solid, and also being familiar with the 109, l think your lathe will appreciate it.

The first thing on the list for machining, then, would be the throw so the oversize of the mains will help keep things together during the interrupted cut. Once the throw and the inner surfaces of the counterweights are done, you'll want to make yourself a spacer to put between the counterweights directly in-line with the mains. I've soft-soldered blocks in there, made bolt-in spacers, whatever works so that you prevent the shaft from flexing.

I haven't tried using the fixtures to offset the throw, looks like it should be put on my to-do list though. I've always just center-drilled the ends of the shaft; but being able to set it back up in the same fixtures later would have its advantages.

Kevin

Hi Foozer.
" I've soft-soldered blocks in there, made bolt-in spacers, whatever works so that you prevent the shaft from flexing."
Simple way: Use Loctite, heat it to remove, works great. ;D
And take the time needed(small cuts)
Regards CS

 

[Philjoe5]

Nice going Foozer. You're jumping in with a fair challenge but so far it looks like you're going to land on your feet. :bow:

Cheers,
Phil

 

[Kermit]

I'm following along. Got about 3/4 of the preceding understood, but am struggling to locate the "newbie" section. ;D

Joeby, you said "remove as much of the material as possible on the throw".

Is that the offset area of the crank where the piston will connect? Meaning to remove the stock by hand before starting the offset turning on the lathe?

 

[chuck foster]

looking good foozer, when you get the crank done will you be building a steam engine to go with it ?

keep up the good work Thm:

chuck

 

[joeby]

Kermit,

Yes, that is what I was referring to. The "throw" or offset bearing surface for the connecting rod can be nasty to cut on the lathe because you have so much material to remove from one side. The interrupted cut makes it very easy to feed in too much at once with sometimes disastrous results. I usually mill out most of the material from between the counterweights before setting up the lathe; but a hacksaw, bandsaw, file, grinder, etc. will get rid of a lot of the excess. You could even "chain" drill it out. Makes for much less stress on you and your lathe.

Kevin

 

[Foozer]

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

Another adventure of making a jig to do a thing

I can't see it
Where's the newbie part?
;D

The knocks on my head from the wall that keeps hitting it as I work on this puzzle 

As it is with most anything, there are 101 ways to do it. It looks like you have a good start, and realizing that you have one of the "not the most rigid machines", I think the next item to be handled would be to remove as much material as possible on the throw.

That’s where some of the head knocking comes in. As the plan is to also incorporate the crank scallops deciding which to do first is, well heads the throw tails the scallop, it was tails.

I started with a AA109....Its tougher to do what you've done than you make it look!

Your doing a great job...keep at it!
Dave

Yup Rigid is not in its vocabulary, got to be slow and easy, but then If I cant make a semi decent collection if parts at this level, the problem is me and not the machine.

Hi Foozer.
" I've soft-soldered blocks in there, made bolt-in spacers, whatever works so that you prevent the shaft from flexing."
Simple way: Use Loctite, heat it to remove, works great. ;D
And take the time needed(small cuts)
Regards CS

From what I have read, yup, take a shortcut and bend the item.

Nice going Foozer. You're jumping in with a fair challenge but so far it looks like you're going to land on your feet. :bow:

Cheers,
Phil

Might be a 3-point landing, wouldn’t be the first time tho

looking good foozer, when you get the crank done will you be building a steam engine to go with it ?

keep up the good work Thm:

chuck

Something will make its presence known, I’m sure I’ll come across a gizmo that needs a crankshaft to be whole again.


Just wanted to touch bases. Not much of a typer, two finger special here and so after another 12 or so hours I got to this stage

Want to cut the scallops in the crank and the only way I could devise is to hold the crank stationary and use a between center shaft to hold a cutting bit. After a bottle of aspirin I got the dimension settled down to cut the curves where I want them. The crank C/L has to be a bit higher than the cutter C/L so I’m not sure how it will work.

Crank held in its turning jig, bolted to bar stock, bolted to plate that will replace the slide. Rube Who? Anyway a slow and go is ahead all it ca do is go POOF?

And whoever brought up take a small project motor with you when ya go-a-begging, It Works. Got some machined flat plate from the local shop for free after he stopped chuckling over what I was trying to do. Next time a box of Donuts. When all else fails, resort to bribery.

Shall

 

[mklotz]

And whoever brought up take a small project motor with you when ya go-a-begging, It Works. Got some machined flat plate from the local shop for free after he stopped chuckling over what I was trying to do. Next time a box of Donuts. When all else fails, resort to bribery.

Told ya.

Take your "pocket engine" with you when you travel anywhere on a ship, too. It's a great "key" for getting a tour of the engine room and the machine shop.

 

[stevehuckss396]

Nice work so far.

 

[Foozer]

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

Still working on teasing the crankshaft out of its hiding place. The funny thing is tho, days can go by where its too cold to spend time in the barn and during this time no one, nada, not a soul drops by. But finally the temp goes up a few degrees and O-Boy time to play with shinny things, yup everyone and there talkative cousin shows up. . .

So after some pondering this contraption developed to remove the bits that are not of the crankshaft. I see where some sort of additional support would be handy to reduce the flex of the long bar, for now just that it does seem to be working is sufficient.

This is after some 16 hours of barn time, 90 percent of it making the jigs

Next is to flip it 180 degrees and chip away the other side. Time will tell and I got lots of that. Down side is If I dont get away from this addictive hobby and cut up a few cords of wood its gonna be real cold in the home come next winter

 

[Maryak]

Foozer,

110% each for imagination, jiggling about and perseverance. :bow: :bow: :bow:

Best Regards
Bob

 

[Foozer]

Foozer,

110% each for imagination, jiggling about and perseverance. :bow: :bow: :bow:

Best Regards
Bob

Thats funny, the "Bride" uses a term resembling a Horses Behind when i say "I'm off to the barn Honey, I have to do important Guy Stuff"

 

[joeby]

There has to be something in this thread for those that feel an AA109 makes only a marginal boat anchor!

Nice, and very creative.

Please do be careful with the bolt driving your boring bar. I know you are aware of it; but it's easy to get too comfortable with it being there.

Kevin

 

[Foozer]

There has to be something in this thread for those that feel an AA109 makes only a marginal boat anchor!

Nice, and very creative.

Please do be careful with the bolt driving your boring bar. I know you are aware of it; but it's easy to get too comfortable with it being there.

Kevin

Your right, that bolt did make me a tad twitchy. Only take a moment of distraction to get a finger clipped, SO. . . addressing the point, shortened bolt, took a 3 inch PVC cap, bored a hole in the end to snug fit the boring bar and now the dog drive is fully enclosed. Two bucks of plastic, twenty minutes of time and the fingers get to stay put.

Before and after shot

 

[Kermit]

Foozer, that looks too simple to be the answer!

Good work - All of it. Now it's time to confess to us.

You're not a 'newbie' and it is extremely obvious to those of us who are!


You keep blazing the trail my friend, I'll be along shortly, thanking all those before who helped show the way,
Kermit

 

[Foozer]

Foozer, that looks too simple to be the answer!

Good work - All of it. Now it's time to confess to us.

You're not a 'newbie' and it is extremely obvious to those of us who are!

I'm just to thick headed to realize I haven't a clue. Compared to some of the stuff I see here, well my knuckles are getting raw from dragging the ground

You keep blazing the trail my friend, I'll be along shortly, thanking all those before who helped show the way,
Kermit

If it wasn't for all the tidbits of info found in this board, this little exercise would be hopeless.
And to that lets see what after 21 hours of "Thump Thump Thump" has wrought.

Still have some more of the Blue to remove

Lot easier on paper than real life

Haven't figured out how to whittle down the small end yet (crank throw). If I stare at it long enough something will show.

side note, argued with the chainsaw a bit today, wouldn't idle, after yelling at every tree around I finally noticed the saw has a low speed fuel adjuster, DUH! I know them trees are laughing at me

 

[joeby]

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.

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?

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