Con-rods and length

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TahoeSteam
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Re: Con-rods and length

Post by TahoeSteam » Thu Oct 17, 2019 1:30 am

Did you decide on traditional journal bearings or roller bearings?
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Re: Con-rods and length

Post by Mike Rometer » Thu Oct 17, 2019 8:39 am

TahoeSteam wrote:
Thu Oct 17, 2019 1:30 am
Did you decide on traditional journal bearings or roller bearings?
Single row sealed ball, as the whole crank is on ball races, but I've made the journals split for easy removal if required. Pictures will follow on the other post when they are nearer completion. Trouble is ATM I'm running on several fronts at once. Note to self "Must learn to calm/slow down." It's a hobby!
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Re: Con-rods and length

Post by Mike Rometer » Mon Nov 09, 2020 3:18 pm

Mike Rometer wrote:
Wed Oct 16, 2019 3:26 pm

8" con-rods, giving a stroke/rod ratio of 2.42424 etc.

I don't think it will look ungainly or over-tall.

Now I'm wondering should I make them a fancy section . . . . . :roll:
Referring to the other thread "And Now or the Twin" I finished rounding the small-end yolks and screwed them to the con-rods. Then I discovered the faux pas! Measuring the centres, they seem to be (ARE!) 9" instead of 8". :o That would push the ratio out to 2.7ish. I must now contemplate if it's worth reducing them back to 8". This is what happens when you keep putting projects down and picking them up again months later! :roll:
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Re: Con-rods and length

Post by TahoeSteam » Mon Nov 09, 2020 9:36 pm

Is there/will there be any interference caused by the longer rods? If not, I'd suggest just running them. That is unless you just absolutely cannot stand it.
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Re: Con-rods and length

Post by Mike Rometer » Mon Nov 09, 2020 10:47 pm

TahoeSteam wrote:
Mon Nov 09, 2020 9:36 pm
Is there/will there be any interference caused by the longer rods? If not, I'd suggest just running them. That is unless you just absolutely cannot stand it.
Fortunately I haven't yet cut the pillars,or even started to the valve gear, so little reason why not.
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Re: Con-rods and length

Post by Mike Rometer » Wed Nov 11, 2020 9:58 am

Despite there being no reason not to leave the extra length on the rods, pride (it comes before the fall), devilment, determination, whatever, I decided to reduce them anyway. Carefully re-measured, marked, set up in the lathe, picked up the thread and cut. No problems! (?) Having completed, I placed my largest digi vernier into the bearing holes and Aaagghhhhhhhhhhh ( :? the fall?) it seemed under-size. Then I remembered that with that vernier you need to add 1/2" to all inside measurements. :oops: :lol: Dohh!

Con-rods (8) (600 x 450).jpg
Con-rods (8) (600 x 450).jpg (70.84 KiB) Viewed 4640 times

Checking both they are equal within 0.003" centre to centre, and weight difference just on 0.3gm. I'll live!
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Re: Con-rods and length

Post by Lopez Mike » Thu Nov 12, 2020 3:45 am

I'm so glad to see someone else using anti friction bearings. Even my Strath single still has a plain brass big end though the mains are single row balls.

If I ever have any trouble with the big end I will re-engineer the crank for a sealed ball bearing. That would leave me with only one oil cup for the crosshead. My eccentrics are ball bearing now. Now if I could only figure out a Watts linkage or some such thing to get rid of that last sliding surface.

Of course without all of the gore slinging about the engine would probably rust away.

Let's see. Go to a zero drip stern packing. No lubrication of the engine. No internal oil already. Next comes the tiled floor and red velour cushions I suppose. I can always get all cranked up about marlin spike ornamentation I suppose. Turk's heads all over the place. Not soon.

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Re: Con-rods and length

Post by fredrosse » Thu Nov 12, 2020 8:16 am

Crosshead - How about a roller bearing arrangement? Watt mechanism would be wonderful, but takes up lots of space, and has pivoting joints that also need bearings. A roller (or ball) bearing, with a spherical outer race (common on many self-aligning pillow blocks or flange bearings), riding in a cylindrical crosshead guide. That could eliminate this sliding bearing location.
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Re: Con-rods and length

Post by Lopez Mike » Fri Nov 13, 2020 4:21 am

I'll give that some thought. I've always liked Watts linkages because there were just pivots. No siding areas that drip oil all over the place.

The one such engine I have is just a Stuart walking beam engine and the loads are very light. On my launch engine the needle bearings for the pivots would have to take some forces and be sealable to suit me.

Oh, well. Wiping oil off of the engine gives me something to do while I'm waiting for a babe to walk down the dock looking for a ride.

Mike
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Re: Con-rods and length

Post by RNoe » Fri Nov 13, 2020 4:39 pm

Lopez Mike wrote:
Fri Nov 13, 2020 4:21 am
[snip]
Oh, well. Wiping oil off of the engine gives me something to do while I'm waiting for a babe to walk down the dock looking for a ride.


Funny, Mike!
Wiping down the engines also gets us up close for periodic inspections.
Always a good idea with reciprocating machines.
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