Radius on big end bearings

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John E. Guitar
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Radius on big end bearings

Post by John E. Guitar » Mon Aug 05, 2019 6:27 am

I’m machining new big end bearings for my 26 Tourer. What radius should I put on these? I found a mention of 1/16” as the fillet radius on the conrod journals on the crankshaft in a post on the old forum so I was thinking I should make it slightly bigger than that.

The pic below is a rod I used to test my setup.

96930734-7172-4CF2-AF91-1B5E1B66ED46.jpeg


BobShirleyAtlantaTx
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Re: Radius on big end bearings

Post by BobShirleyAtlantaTx » Mon Aug 05, 2019 10:19 am

The shaft should have a radius of 1/16 at the rod pins so I cut just a tad over a 1/16. Very nice looking pour, please show us your set up. Also the fixture for boring the rods. Bob 903 824 1949
image.jpg


Kevin Pharis
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Re: Radius on big end bearings

Post by Kevin Pharis » Mon Aug 05, 2019 3:50 pm

Test rod?!?!? Looks more like a lightened racing rod to me!! ;)


Adam
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Re: Radius on big end bearings

Post by Adam » Mon Aug 05, 2019 8:27 pm

A 1/16” radius certainly will not work with a correctly ground crank!

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John E. Guitar
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Re: Radius on big end bearings

Post by John E. Guitar » Mon Aug 05, 2019 10:37 pm

Bob, thanks, I'll go with that.

You've got a nice setup. It's interesting seeing how you've held the big end. That was the part I wasn't sure which way to go.

Here is what I came up with. The base and end plate is scrap 6061 T6, and the pin is mild steel. I've got our another bearing to pour this week, I'll take photos of my mold setup then.

Conrod fixture.JPG


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Re: Radius on big end bearings

Post by BobShirleyAtlantaTx » Tue Aug 06, 2019 12:22 am

The rod pictured has no babbitt it was used for setup. The fixture clamps the rod using pins and the large bolts on either side of aviation socket head bolts, cut flat on the inside of the head to go into the rod. The long, splicing nuts are used with a gauge block to check the straight and twist of the rod.
D14E77D0-CC99-4F01-8B1A-A2DBFCD8E5D3.jpeg
The bolts in the fixture push on pins that clamp against the socket bolts. The pins have a flat on one side and the small socket bolts keep the pins oriented.


Bill Crosby
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Re: Radius on big end bearings

Post by Bill Crosby » Tue Aug 06, 2019 7:29 pm

This Is the rod boring setup that I have developed over the years.
Attachments
DSCN3431.JPG


Kohnke Rebabbitting
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Re: Radius on big end bearings

Post by Kohnke Rebabbitting » Tue Aug 06, 2019 9:25 pm

C to C, is 7 inches.

Width is 1.500.

The Radius is exactly 1/8th.

First rod, Gold, is our Centrifugally poured Rods

Herm.
Attachments
Model T Spun Poured Rod 004.jpg
Model T Rod, Jig Poured 010.jpg
Model T Rod, Jig Poured 004.jpg
Jig Poured Model T Rods, Jan, 2012 029.jpg
Jig Poured Model T Rods, Jan, 2012 026.jpg
Jig Poured Model T Rods, Jan, 2012 026.jpg (21.86 KiB) Viewed 688 times

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John E. Guitar
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Re: Radius on big end bearings

Post by John E. Guitar » Wed Aug 07, 2019 10:04 pm

Bill, that is a great looking setup. The way you've done the big end adjustments must cut down on setup time a lot.

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Re: Radius on big end bearings

Post by John E. Guitar » Wed Aug 07, 2019 10:07 pm

Herm, thank you, that is good information.

Is the gold rod photo in your post as poured? Do you have a side-on photo? It's hard to compare it with the static-pour rod being from two different angles.

I can see you had leakage with the static-pour rod. I used a combination of aluminium welding wire and Eastwood heat compound to eliminate that. Do you think the colour variation would correspond with different grain structure? I noticed when I was machining one of my rods there seemed to be a few hard spots in the babbitt.

I'm envious of your centrifugal casting setup, the end result looks great.


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Re: Radius on big end bearings

Post by Kohnke Rebabbitting » Thu Aug 08, 2019 3:57 pm

John E. Guitar wrote:
Wed Aug 07, 2019 10:07 pm
Herm, thank you, that is good information.

Is the gold rod photo in your post as poured? Do you have a side-on photo? It's hard to compare it with the static-pour rod being from two different angles.

I can see you had leakage with the static-pour rod. I used a combination of aluminium welding wire and Eastwood heat compound to eliminate that. Do you think the colour variation would correspond with different grain structure? I noticed when I was machining one of my rods there seemed to be a few hard spots in the babbitt.

I'm envious of your centrifugal casting setup, the end result looks great.
On the leakage John, That was the first time we static poured, about 7 years ago, on Model T rods, and as the pour came out, we don't put up with leakage. So, I set up a jig to machine the rod sides. So the uneven machined sides, from previous rebuilding machine work, was gone.

I will show you the jig pictures, and machined rods, before pouring, it is a factory, Clawson & Bals.

The Gold rod is the one we always took to swap meets.


The dark rod is a clawson & Bals, spun poured Rod


Herm.
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Model T Spun Poured Rod 008.jpg
Model T Spun Poured Rod 008.jpg (19 KiB) Viewed 540 times
Model T Spun Poured Rod 004.jpg


Kohnke Rebabbitting
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Re: Radius on big end bearings

Post by Kohnke Rebabbitting » Thu Aug 08, 2019 4:11 pm

More Pictures.
Attachments
Model T, Pre-Maching Rods For Pouring. 026.jpg
Model T, Pre-Maching Rods For Pouring. 018.jpg
Model T, Pre-Maching Rods For Pouring. 007.jpg
Model T, Pre-Maching Rods For Pouring. 003.jpg
Model T, Pre-Maching Rods For Pouring. 002.jpg


Kohnke Rebabbitting
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Re: Radius on big end bearings

Post by Kohnke Rebabbitting » Thu Aug 08, 2019 4:21 pm

Pictures.
Attachments
Model T, Pre-Maching Rods For Pouring. 044.jpg
Model T, Pre-Maching Rods For Pouring. 038.jpg
Model T, Pre-Maching Rods For Pouring. 034.jpg
Model T, Pre-Maching Rods For Pouring. 032.jpg
Model T, Pre-Maching Rods For Pouring. 028.jpg


Kohnke Rebabbitting
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Re: Radius on big end bearings

Post by Kohnke Rebabbitting » Thu Aug 08, 2019 4:28 pm

Pictures.
Attachments
Model T, Pre-Maching Rods For Pouring. 065.jpg
Model T, Pre-Maching Rods For Pouring. 063.jpg
Model T, Pre-Maching Rods For Pouring. 058.jpg
Model T, Pre-Maching Rods For Pouring. 050.jpg
Model T, Pre-Maching Rods For Pouring. 049.jpg


Kohnke Rebabbitting
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Re: Radius on big end bearings

Post by Kohnke Rebabbitting » Thu Aug 08, 2019 4:42 pm

Pictures.
Attachments
Spun Cam Bearings 005.jpg
Spun Cam Bearings 003.jpg
Model T, Pre-Maching Rods For Pouring. 068.jpg
Model T, Pre-Maching Rods For Pouring. 067.jpg
Model T, Pre-Maching Rods For Pouring. 066.jpg


Kohnke Rebabbitting
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Re: Radius on big end bearings

Post by Kohnke Rebabbitting » Thu Aug 08, 2019 4:56 pm

Pictures
The car is a 1908 Aplex, 2 Cycle, quite a Machine.
Attachments
1908 Aplex 020.jpg
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Spun Cam Bearings 009.jpg
Spun Cam Bearings 008.jpg

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