Page 3 of 8 FirstFirst 12345 ... LastLast
Results 21 to 30 of 72

Thread: Dumb machining questions. The jig that an engine gets bolted to for machining called?

  1. #21
    Join Date
    Sep 2009
    Location
    NW Illinois USA
    Posts
    732

    Default

    I made a matched pair of main bore datum simulators for block machining. Each was about 4 inches long and main bore diameter with a 5/8 wide key machined in the bottom to match mill table tee slot. I bolted them to the table then place the block on the simulators. Automatically aligns the main bore to the tee slot. Fill the gap under the pan rail with packing and clamp. Worked great for decking inline six cylinder blocks.

    v8 the same idea would work but would need to consider table clearance and packing/clamping won't be as convenient. I offer this as food for thought if you plan to build some fixturing. I did it with an 8 inch long piece of round steel about 3 inch dia, no other expense.

    If you use the opposite deck to fixture, how will you pick up the main bore for alignment?

  2. #22
    Join Date
    Dec 2009
    Location
    Stevens Point, WI
    Posts
    8,124

    Default

    Quote Originally Posted by strokersix View Post
    I made a matched pair of main bore datum simulators for block machining. Each was about 4 inches long and main bore diameter with a 5/8 wide key machined in the bottom to match mill table tee slot. I bolted them to the table then place the block on the simulators. Automatically aligns the main bore to the tee slot. Fill the gap under the pan rail with packing and clamp. Worked great for decking inline six cylinder blocks.

    v8 the same idea would work but would need to consider table clearance and packing/clamping won't be as convenient. I offer this as food for thought if you plan to build some fixturing. I did it with an 8 inch long piece of round steel about 3 inch dia, no other expense.

    If you use the opposite deck to fixture, how will you pick up the main bore for alignment?


    I plan to use a coaxial indicator setup to locate the existing bore top and bottom, then insert boring head and go. It will take quite some time to dial in the block to the angle plates but I should only have to do it twice. I still plan to use some support under the opposite end of the block from the angle plate and clamps to make sure it stays put.

    Looking tonight I will have to use 100% of the quill travel as well for the bore.

    I will have to keep an eye out for one of those van norman 777's. They look handy!
    Andy

  3. #23
    Join Date
    Apr 2017
    Location
    Kelowna BC
    Posts
    2,415

    Default

    I did something with V8 heads that might be easier.
    Make 1/2 plates that bolt to end a of the block the mill them close to parallel to the bores or deck.
    The shim those if needed as you clock In and clamp.

    I did it to heads I think to do valve spring or stud work, which us not parallel to head gasket surface. Worked well.
    Last edited by 754; 06-04-2019 at 09:46 PM.

  4. #24
    Join Date
    Sep 2009
    Location
    NW Illinois USA
    Posts
    732

    Default

    Quote Originally Posted by vpt View Post
    I plan to use a coaxial indicator setup to locate the existing bore top and bottom, then insert boring head and go. It will take quite some time to dial in the block to the angle plates but I should only have to do it twice. I still plan to use some support under the opposite end of the block from the angle plate and clamps to make sure it stays put.

    Looking tonight I will have to use 100% of the quill travel as well for the bore.

    I will have to keep an eye out for one of those van norman 777's. They look handy!
    So you plan to follow the existing bore without reference to the crankshaft axis. That's ok but you don't know where the existing cylinder bores are relative to the crankshaft. Whether this matters to you is obviously your decision. Probably close enough.

  5. #25
    Join Date
    Dec 2009
    Location
    Stevens Point, WI
    Posts
    8,124

    Default

    Quote Originally Posted by 754 View Post
    I did something with V8 heads that might be easier.
    Make 1/2 plates that bolt to end a of the block the mill them close to parallel to the bores or deck.
    The shim those if needed as you clock In and clamp.

    I did it to heads I think to do valve spring or stud work, which us not parallel to head gasket surface. Worked well.
    In my searching I saw something similar and it does look like a nice setup. I just got the angle blocks because I figure I can use them in the future. Ultimately I would like the bar and endplate type fixture. Seems very versatile.

    Quote Originally Posted by strokersix View Post
    So you plan to follow the existing bore without reference to the crankshaft axis. That's ok but you don't know where the existing cylinder bores are relative to the crankshaft. Whether this matters to you is obviously your decision. Probably close enough.


    Yeah, I am only going .020" over own my own junk, close enough is good enough.
    Andy

  6. #26
    Join Date
    Apr 2017
    Location
    Kelowna BC
    Posts
    2,415

    Default

    I built end plates for the the big block heads because I lacked a 20 or 24 inch tilt table with trunnions.

  7. #27
    Join Date
    Sep 2009
    Location
    NW Illinois USA
    Posts
    732

    Default

    You could set up your crankshaft between your angle plates, dial it in, then set the block on the crank. This would give you a known starting point of the crankshaft axis. A bit floppier than the way I did it with solid rounds attached to the table but still should work and would give you table clearance to roll 90 degrees. If you need to adjust cylinder bore position for cleanup or to match factory cylinder bore position or to maintain cylinder wall thickness at least you know your starting point.

    Apologies for beating a dead horse but it seems to me to be similar work as your proposal with better results and understanding.
    Last edited by strokersix; 06-05-2019 at 10:40 AM.

  8. #28
    Join Date
    Sep 2009
    Location
    NW Illinois USA
    Posts
    732

    Default

    You could even clamp the block to the crankshaft with main caps by adding paper shim in place of oil film thickness between bearing and crank main journals.

  9. #29
    Join Date
    Dec 2009
    Location
    Stevens Point, WI
    Posts
    8,124

    Default

    I got the blocked stripped down and surfaces cleaned up. I trammed the mill in (found out the dial indicator I have been using for some time is slopped out). Started to mock up the block just to get an idea on how to orientate it and what it will take to clamp it down. First thing I had to do was make up a set of machinist jacks, I've been meaning to do this for awhile now. They aren't elegant but they do their job, I can change them up later on if I need too.

    7/16x20NF bolts with the tops turned down flat. The blocks are around 2" tall drilled and tapped all the way threw.



    No studs in the clamps yet. I didn't have studs long enough, my longest was just 1/4" short. I don't think I have sleeves (extra long nuts) to double them up either, I will have to look around tomorrow.



    The other side. This is the block surface I plan to attach the angle plate(s) too and bolt down to the table. A bit far away from the cylinders being bored, that why I working on the support on the other end as well.




    I am waiting for three things to come in now, coaxial indicator, angle plates, and carbide boring bars. I have "boring bars" (or is it boring head tooling?) but I wanted new fresh purpose made bars. With all these tools I figure I will get years of use out of each for many different projects down the road. So I don't feel I am spending all the 'tooling money' for this one project that may not work out. haha

    Stick around for this clown show! Its about to get entertaining!
    Andy

  10. #30
    Join Date
    Oct 2012
    Location
    San Antonio TX, USA
    Posts
    2,635

    Default

    Neat! Looking forward to seeing how you finalise the set up.

    I bought a bunch of cheapo 12mm SCLCR boring bars off ebay or wherever and cut them to different lengths. Even got an SCLCL bar for outside bosses or using the "cross hole" on the boring head.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •