Author Topic: 1/4 scale Porsche 917 180 degree V12 Build  (Read 57515 times)

Offline Art K

  • Full Member
  • ****
  • Posts: 1761
  • Madison, Wisconsin USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #390 on: December 05, 2022, 07:54:54 PM »
Dave,
On vacation, it's good to sit down and have the time to get cought up with your build. One question, how much of a gap between the two halves of each throw? I am following that the bearing in between locates the faces. Presumably the gap doesn't matter so much. I do have a pdf of the Schilling book but "mein Deutch ist sehr schleckt" is there an English version available? Wonderful work!
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #391 on: December 05, 2022, 08:23:51 PM »
Dave,
On vacation, it's good to sit down and have the time to get cought up with your build. One question, how much of a gap between the two halves of each throw? I am following that the bearing in between locates the faces. Presumably the gap doesn't matter so much. I do have a pdf of the Schilling book but "mein Deutch ist sehr schleckt" is there an English version available? Wonderful work!
Art

Im shooting for an .0005 interference fit.   :ROFL:  As a bush it is that, and the caps close up completely, and the bush is immobile.         That's the target anyway....we will see.
the fixture is going to be a key component in this operation, splitting these bushes exactly in half is what Im going to try to do.     Then I'll need a fixture to hold them for final boring and finally reaming while clamped.....it's going to be tedious at best!     this is pushing me to a level of consistency that I'm not sure I can do....but I will try...and the only down side of trying is scrapping some bronze bushes....so the risk is pretty low.....comparitively.

And no I don't know of an English version of this book, though Mike and I have had some luck using the Google translator.  At the end of the day, the drawings speak pretty well for themselves.
Dave
« Last Edit: December 05, 2022, 08:32:20 PM by steamer »
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Art K

  • Full Member
  • ****
  • Posts: 1761
  • Madison, Wisconsin USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #392 on: December 05, 2022, 09:01:45 PM »
Thanks!
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #393 on: December 06, 2022, 02:19:12 AM »
First pair fit perfect!    On to the rest
« Last Edit: December 06, 2022, 06:19:57 AM by steamer »
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline RReid

  • Full Member
  • ****
  • Posts: 1668
  • Northern California
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #394 on: December 06, 2022, 02:25:04 AM »
YeeHaw!! Lookin' great, Dave.
Regards,
Ron

Offline crueby

  • Full Member
  • *****
  • Posts: 18554
  • Rochester NY
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #395 on: December 06, 2022, 02:43:06 AM »
Beautiful!

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #396 on: December 06, 2022, 05:30:14 AM »
15 pairs of bearing shells up to op2.  They need to be drilled....but not tonight.
« Last Edit: December 06, 2022, 06:20:57 AM by steamer »
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 6133
  • Switzerland
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #397 on: December 06, 2022, 11:30:10 AM »
Looking good  :praise2: Are you going to finaly ream the bores when they are assembled or are the production tolerances tight enough?
Best regards

Roger

Online Vixen

  • Full Member
  • *****
  • Posts: 3075
  • Hampshire UK
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #398 on: December 06, 2022, 12:16:57 PM »
15 pairs of bearing shells up to op2.  They need to be drilled....but not tonight.

15 pairs of half bearing shells from 30 complete bearing rings :praise2:      Well done, you have not lost any yet :praise2:

But you must have got through a whole lot of bar stock and made a mountain of shiny chips. Shame you cannot find a use for the undersize half of the bearing shells.

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #399 on: December 06, 2022, 01:01:10 PM »
Oh far from
Killed 3 on op1
Killed 4 on op 2
Had to make more last night to get 15
Went through 18" of 1/2 " bronze bar.
And I still have more ops to do!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #400 on: December 06, 2022, 02:43:09 PM »
Looking good  :praise2: Are you going to finaly ream the bores when they are assembled or are the production tolerances tight enough?

I'm building a locating fixture to bore and then ream to final size.   

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline jcge

  • Full Member
  • ****
  • Posts: 87
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #401 on: December 09, 2022, 09:27:44 AM »
Dave - this typ.912 engine is one of my favourite engineering designs.
Really enjoying the way your going about this build and documenting and sharing it.
Regards
John

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #402 on: December 09, 2022, 04:03:18 PM »
Dave - this typ.912 engine is one of my favourite engineering designs.
Really enjoying the way your going about this build and documenting and sharing it.
Regards
John

Thank you John,   Im trying     The machining challenges of this engine are pretty epic to me.    I rarely have to do 12 of anything, and making 12 exactly alike...or as close as I can get....has been a real challenge to me    It's upping my game for sure!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #403 on: December 09, 2022, 04:26:17 PM »
Oh far from
Killed 3 on op1
Killed 4 on op 2
Had to make more last night to get 15
Went through 18" of 1/2 " bronze bar.
And I still have more ops to do!

Dave

Dave - this typ.912 engine is one of my favourite engineering designs.
Really enjoying the way your going about this build and documenting and sharing it.
Regards
John

Thank you John,   Im trying     The machining challenges of this engine are pretty epic to me.    I rarely have to do 12 of anything, and making 12 exactly alike...or as close as I can get....has been a real challenge to me    It's upping my game for sure!

Dave

Observations on my mill while making these bearings.   After the 4th bearing I noticed that the fixture was being rubbed by the cutter during the cut....the first 4 did not do that    I checked for chips under the fixture, but I didn't find any, and it was starting to cut bad parts....hmmm

The cutter was in it's holder tight, and I wasn't removing the tool holder between parts, and the tool was taking a .010" facing cut in bronze.....so it was very unlikely I was pulling the cutter out...and the amount was very small....  I checked the cutter and it wasn't worn.    OK...so the machine tool Engineer in me screamed "Thermals"

The only coolant on the machine is mist lube ( compressed air/mist) and as it was bronze i wasn't using it.    As the spindle was running at 4000 rpm, and it was a couple of minutes long cycle,   I suspected that the spindle nose/toolholder were warming up and growing in length......   

So I added coolant to the program, and I aimed the air jet at the middle of the tool holder.      Let it sit for a minute or 2 and tried again but now with coolant on.

It immediately started to behave like the first cut!    Ha ha!   so I then cut the rest of the 30 parts that way  ( 38 or so in total including the scrap ones.)  and the tolerance was +/- .0005' which considering it's not a precision mill by any means,  was pretty good!!!

Just some of the things you run into when you're running "production"...which is something I rarely do.

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online Vixen

  • Full Member
  • *****
  • Posts: 3075
  • Hampshire UK
Re: 1/4 scale Porsche 917 180 degree V12 Build
« Reply #404 on: December 09, 2022, 04:42:49 PM »
Hello Dave,

"Thermals"..... Yes, they can be a problem with repetitive work. It's one of the reasons I do little machine shop work during the winter months. The machinery is my unheated outside workshop can get very cold overnight. If I put the fan heater on to get the shop warm enough to work in, the machines get a thermal shock, slowly start to warm and expand. Any ideas about maintaining tight tolerances go out the window.

Mike   :atcomputer:
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal