Aero engine rescue

[SED]

Chuck that is great!  In 5 min. reading your post I learned several great tricks.  I inherited an old (1944!) Craftsman 3" lathe from my grandfather (really a toy!) that I've used to make a few things but never cut threads.  You make it seem doable.  Thanks!   

Hope it's ok if I ask a couple questions?  How do you pick the steel for bolts?  You specify O8 tool steel.  Looking up tool steel gives a myriad of info yet it seems like we would only need 4 types: mild steel, tough tool steel for bolts and wear parts, hard steel for cutting and spring steel for springs?  Is your machinist's bible the reference?

I also need to figure out how to sharpen the tool bits better and centering the work in the headstock easier...
Thanks again!
Shawn

[Zinfan]

I'm fascinated by lathes and mills so loved the thread cutting pics.  I like to think if I had room I'd get a baby lathe to work with but alas the garage is too small.  I like to watch Keith Fenner's videos on youtube as he does lots of Machinist work that involves the lathes.

[Chuck in Indiana]

You're right, Terry.. I didn't do a very good job of documenting how a manual lathe works. The three aluminum pulleys to the left control spindle speed. The plastic gear that is driven off the spindle is sacrificial on this lathe, and drives the feed and threading mechanism. The placard on the front tells which combination of gears causes the leadscrew to turn, and how much it turns per revolution of the spindle. The leadscrew drives the carriage via two half nuts that are clamped to it with a lever.
 
This is the "lever a" on the placard. You can see it is put in position 1.

The leadscrew drives the "carriage". Mounted to the carriage is the cross slide, which moves in and out, with the compound on top. It is rotatable, so tapers can be turned, and can be used for anything needing an angle. It is set on 60 degrees to cut this thread. You can see the leadscrew.. a long threaded rod.. that the half nuts clamp to to move the carriage. The lever to the right is for threading, the other lever near the file handle is for the power feed for turning.

That's about it. No matter who makes them, all lathes work approximately the same way, and if you can run one, you can run em all.. 

[Chuck in Indiana]

Chuck that is great!  In 5 min. reading your post I learned several great tricks.  I inherited an old (1944!) Craftsman 3" lathe from my grandfather (really a toy!) that I've used to make a few things but never cut threads.  You make it seem doable.  Thanks!   

Hope it's ok if I ask a couple questions?  How do you pick the steel for bolts?  You specify O8 tool steel.  Looking up tool steel gives a myriad of info yet it seems like we would only need 4 types: mild steel, tough tool steel for bolts and wear parts, hard steel for cutting and spring steel for springs?  Is your machinist's bible the reference?

I also need to figure out how to sharpen the tool bits better and centering the work in the headstock easier...
Thanks again!
Shawn

Sure thing, Shawn.. although I'd be surprised if that small a lathe has change gears for thread chasing. In picking the steel for these studs, *if it was easily available and cheap* (Guzzi content)  I'd probably have gone with a chrome moly high carbon steel. It's not..oh, I could have found some, but I don't think it's necessary. I chose 01, that's a standard oil hardening tool steel that is pretty tough in the normalized condition. If necessary (I don't think it will be) I can easily harden and temper it with an ox acetylene torch and a pan of kerosene. 

Oh.. everything imaginable is in the Machinerys handbook..    including steel types and uses.
Showing someone how to shape a cutting tool is beyond a thread like this.. but.. the trick is to make sure it (the cutting edge) has positive clearance without having too much. Without enough, it will rub and not cut at all or leave a nasty finish. Too much, and the cutting edge will get hot and dull in short order.
There's a little learning curve..

[SED]

Sure thing, Shawn.. although I'd be surprised if that small a lathe has change gears for thread chasing.
...
There's a little learning curve..

Thanks Chuck!  It's encouraging to see you do it so nicely.

The little lathe does have a power lead screw and all the cogs to set feed rates.  There's some wear in the split collar that catches the lead screw and more in the head stock bushings which may be the biggest hurdle other than that learning curve!   
Thanks again.
Shawn

[John A]

You can turn a piece of round stock into a square block on a lathe. I've stumped some instructors with that, I had to have it explained to me, by my grandfather who was born in 1901

[Chuck in Indiana]

Thanks Chuck!  It's encouraging to see you do it so nicely.

The little lathe does have a power lead screw and all the cogs to set feed rates.  There's some wear in the split collar that catches the lead screw and more in the head stock bushings which may be the biggest hurdle other than that learning curve!   
Thanks again.
Shawn

Well.. you have a lathe. It's the only machine tool that is capable of duplicating itself.  You can make new head stock bushings..

[Triple Jim]

You can turn a piece of round stock into a square block on a lathe. I've stumped some instructors with that, I had to have it explained to me, by my grandfather who was born in 1901

Sounds like a 4-jaw chuck and a lot of facing.  I do use my vertical mill for turning occasionally, when the part is too big for my 12" lathe.

[John A]

Yeah Jim that's it you hack off a piece of round stock, face off both ends, chuck it in a 4 jaw, face off a side, turn it 180 ,face off another and so on. The whole point is that with machine tools use your imagination and you can build most things you can imagine.

[Doug McLaren]

Chuck, you may, tongue in cheek, refer to your Chinese lathe as a toy and indeed it may well be when compared to tool-room machinery in a production environment. But speaking as a non-machinist my Chinese lathe has been worth every penny that I paid for it. It's ideal for knocking up odd studs, bushes, spacers and collars, for drilling, boring and threading and many other tasks.

Like I said, I'm no machinist and it'll take me a lot longer to do things than a pro but I reckon it's been a great addition to my garage.

[Chuck in Indiana]

Chuck, you may, tongue in cheek, refer to your Chinese lathe as a toy and indeed it may well be when compared to tool-room machinery in a production environment. But speaking as a non-machinist my Chinese lathe has been worth every penny that I paid for it. It's ideal for knocking up odd studs, bushes, spacers and collars, for drilling, boring and threading and many other tasks.

Like I said, I'm no machinist and it'll take me a lot longer to do things than a pro but I reckon it's been a great addition to my garage.

Oh, I *use* my little lathe, but it isn't in the same league as a *real* lathe. It's just not sturdy enough. That said, it's a handy little booger, and obviously I couldn't cut those threads on my LaBlond. I *could* put a die in a special home made holder in the LaBlond's tailstock and get the job done, but I wanted to see if my toy lathe (and I) could do it. It can. 

[twhitaker]

I'm kind of surprised the LeBlond didn't have metric capability.

Our shop has been working on rebuilding or retrofitting big lathes for years. One in our shop right now is a deep hole drill capable of drilling a 12 3/8 diameter hole 65 FEET deep. This machine has a 6 foot swing and is over 200 feet long. Among other things this forge makes is locomotive and ship crankshafts and the Mother Of Of All Bombs.

[Chuck in Indiana]

I'm kind of surprised the LeBlond didn't have metric capability.

Our shop has been working on rebuilding or retrofitting big lathes for years. One in our shop right now is a deep hole drill capable of drilling a 12 3/8 diameter hole 65 FEET deep. This machine has a 6 foot swing and is over 200 feet long. Among other things this forge makes is locomotive and ship crankshafts and the Mother Of Of All Bombs.

It's uh.... pre war, Terry.  Yeah.. *that* one.

[pauldaytona]

I'm kind of surprised the LeBlond didn't have metric capability.

Our shop has been working on rebuilding or retrofitting big lathes for years. One in our shop right now is a deep hole drill capable of drilling a 12 3/8 diameter hole 65 FEET deep. This machine has a 6 foot swing and is over 200 feet long. Among other things this forge makes is locomotive and ship crankshafts and the Mother Of Of All Bombs.

Picture?

[tris]

I'm kind of surprised the LeBlond didn't have metric capability.
.......

ENGAGING OLD MEMMORY CELLS ..... CLUNK

Don't you need a 127 tooth change wheel to screw cut metric on an imperial lathe

[Chuck in Indiana]

ENGAGING OLD MEMMORY CELLS ..... CLUNK

Don't you need a 127 tooth change wheel to screw cut metric on an imperial lathe

Yep.

[tris]

Yep.

Wahoo   my long term memory is OK.

That's good news even if "according to my wife" I can't remember anything

Strange how its always stuff like the 3rd iteration of the 4th colour we might be painting the bathroom in 18 months time I forget 

[Chuck in Indiana]

Wahoo   my long term memory is OK.

That's good news even if "according to my wife" I can't remember anything

Strange how its always stuff like the 3rd iteration of the 4th colour we might be painting the bathroom in 18 months time I forget 

You need not put things like that in long term memory.. it just clogs up the mechanism. <looking over shoulder>
 

[twhitaker]

Up near the headstock is the saddle that supports the drill bushing. The part is supported on steadyrests and by the bushing. The machine uses up to 200 gallons coolant per minute.

[Chuck in Indiana]

Dainty little thang.. 

[Kiwi_Roy]

I did my apprenticeship in a railway workshop, we had a bunch of old machinery taken from Germany at the end of WWII I was always looking at machinery trying to figure out how it worked.
We had a large vertical lathe that could swing about 10 feet.
Chuck, explain how you always start the threads in the right spot for 2nd and 3rd cut etc.

[Chuck in Indiana]

I did my apprenticeship in a railway workshop, we had a bunch of old machinery taken from Germany at the end of WWII I was always looking at machinery trying to figure out how it worked.
We had a large vertical lathe that could swing about 10 feet.
Chuck, explain how you always start the threads in the right spot for 2nd and 3rd cut etc.

Ok, see the teardrop shaped gizmo (technical term) at the top of the paint brush? It can be pivoted down to lock onto the lead screw. Then the indicator wheel with the numbers you can barely see rotates. If you are cutting 'Merican threads any number that is divisible into the number of threads can be used. For instance if it is 12 threads per inch, you can lock in the half nut when it rotates to 1, 3, 4, or 6.
The instructions in the toy lathe manual say when cutting metric threads to leave it locked in, and reverse the head rotation.. so it's tedious. Feed in the compound, turn on the headstock, watch it like a hawk  and turn it off before reaching the end of the cut and let it coast. Back off the compound past zero and reverse the motor.  Feed in for your second pass, etc. Real lathes have a positive stop that can be set on the cross slide so you don't have to do all that. You can just back off the cross slide, feed in the compound, run the cross slide back to the positive stop, etc. You'll be done in a minute or so. It takes several minutes with this little booger.

[John A]

And cue " machine hypnosis"   
That only happens after the part is nearly complete , after hours of work!

[Chuck in Indiana]

Ok, back to the Aero engine. 
Since it's "experimental" the Guzzi Garage (tm) is now the "Experimental Department." 

Back when a top cylinder stud stripped, on the advice of Dick.. who's advice I take seriously  I made new studs out of M8 all thread. Seemed like a good idea at the time, rolled threads instead of cut, but the unintended consequence was an oil leak. I assumed oil was migrating down the minor diameter of the threads.
Yep. Taking the tank off revealed wet threads. It's not like this was some major leak or anything, after a few hundred miles there would be a mist on things. Annoying.


Time to fix it. Made new studs with the toy lathe. That's documented earlier in the thread.
I've mentioned before that having the right tool is many times 2/3 of the job. This is no different. The Kid brought down his stud remover/installer set.. how do it know?  .. to work on his carb Spot, so I borrowed it.
It's for M6, 8, 10, & 12.

Oh, this is *way* too easy.

They don't sell any of those sissy metric O rings in Elwood, Indiana.. we're 'Mericans here. McMaster Carr has them. Got 100 M8s and 100 M10s for about the price of special ordering enough to do the job. Anyone need O rings? 

So. Installed the studs.. this is *much* better than taking a chance of deforming the threads by double nutting, etc. The tool will grip the stud below the threads. I need a set, obviously.  I love tools..

Torqued the studs using the tool to 15 ft. lbs. just like in the book.
Put on the new O rings

Reinstalled the rocker pedestals, torqued, adjusted valves, you know the drill.
This should cure that pesky oil leak.

[John A]

Will it make rated power now, Chuckie ?

[Antietam Classic Cycle]

So. Installed the studs.. this is *much* better than taking a chance of deforming the threads by double nutting, etc. The tool will grip the stud below the threads. I need a set, obviously.  I love tools..

I need a set too. Brand name of the ones you used?

[Triple Jim]

They don't sell any of those sissy metric O rings in Elwood, Indiana.. we're 'Mericans here. McMaster Carr has them. Got 100 M8s and 100 M10s for about the price of special ordering enough to do the job. Anyone need O rings? 

I have quite a few bags of O-rings with 90-99 left in them, but I don't mind.  Like you said, the cost is usually less than buying a few from a parts dealer, and eventually I'll have all sizes in stock and my kids can inherit them.   

[Chuck in Indiana]

Will it make rated power now, Chuckie ?

Nope. It has a mild (er) V65 cam.  It makes "adequate power" though.. Trust me.

[Chuck in Indiana]

I need a set too. Brand name of the ones you used?

Ya know, Charlie.. I brought the Kid up right.  I told him to always buy the best tools he could afford. When he was down working on the Spot, he looked at a puller I had. It was Buffalo. He gave me the *look*, and I told him at that time that was the best I could afford. 
These are Cornwell. Not Snap On or Matco.. but look perfectly adequate for not every day use to me. 

[Antietam Classic Cycle]

Ya know, Charlie.. I brought the Kid up right.  I told him to always buy the best tools he could afford. When he was down working on the Spot, he looked at a puller I had. It was Buffalo. He gave me the *look*, and I told him at that time that was the best I could afford. 
These are Cornwell. Not Snap On or Matco.. but look perfectly adequate for not every day use to me. 

Thanks. I found some that are the best I can afford.