Author Topic: Forest 1889 6 cyl Marine Engine  (Read 3511 times)

Offline ddmckee54

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Re: Forest 1889 6 cyl Marine Engine
« Reply #30 on: May 26, 2021, 03:30:26 PM »
Maury:

If you want Imperial fasteners, 2-56 is about the smallest I've found, I just Googled "3D threaded inserts".  (When I tried "1-72 3D threaded inserts" I didn't get any complete matches.)

I've got a butt-load of M3 button-head SS cap screws so I just use M3 inserts.  I did find a link to M1.6 inserts on Ebay, but I don't think that's much smaller than 2-56 is it?

I suppose you could try "rolling your own" by knurling, drilling, tapping, and parting off brass rod - but is that really worth the effort?
Don

P.S. - I just checked McMaster-Carr, and they've got threaded inserts in various sizes down to 0-80 for less than $14USD per 100. (Sometimes they actually DO have decent prices.)
« Last Edit: May 26, 2021, 03:42:39 PM by ddmckee54 »

Offline maury

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Re: Forest 1889 6 cyl Marine Engine
« Reply #31 on: May 26, 2021, 04:31:38 PM »
Don, thanks for your continued help. I may want the 1's and 3's for future projects, but for now the 2's will be good. As much as I dislike metric, I would be willing to use them. I build scale model antique engines, and i want to use the tall head scale hex bolts. So if I could find the inserts and bolts in the same size I'd be ok with either metric or Imperial. There are also cases where I could use a through stud with a nut on both ends.

Progress on the engine is slowing a bit, but I have managed to assemble the crank to the pistons.

maury
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Offline maury

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Re: Forest 1889 6 cyl Marine Engine
« Reply #32 on: May 27, 2021, 07:52:49 PM »
Well, now we have all the major parts for the lower engine. Can't wait to see what the assembly looks like.
maury
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Offline Dave Otto

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Re: Forest 1889 6 cyl Marine Engine
« Reply #33 on: May 27, 2021, 09:47:53 PM »
That's coming along nicely Maury!

Dave

Offline maury

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Re: Forest 1889 6 cyl Marine Engine
« Reply #34 on: May 29, 2021, 03:39:37 PM »
Dave, thanks for the compliment.

The next part of the engine I want to work on is the Lee Shaft and the gearing for it. This feature is unique to the all of the old engines I'm aware, making it a good modeling candidate. I played with the balance of making gears with teeth large enough to print, but small enough to look authentic. 28DP seems to be a good balance. So far I have printed the crank pinion, and the Lee Shaft driver gear and it's shaft.

maury
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Online crueby

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Re: Forest 1889 6 cyl Marine Engine
« Reply #35 on: May 29, 2021, 04:30:41 PM »
What is a Lee shaft?

Offline maury

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Re: Forest 1889 6 cyl Marine Engine
« Reply #36 on: May 29, 2021, 07:55:17 PM »
Crueby, thanks for tuning in, and the question.

As with most things, there are probably other names for a Lee Shaft.
A Lee Shaft is made up of two rods tied to two cranks ofset by 90 deg. The shafts are tied to cranks of the same dimensions on both ends. The hafts c/c is equal to the of c/c between the shafts attached to the cranks. The purpose is to transfer motion from the driving shaft to the driven shaft. When one of the rods is pulling, the other is pushing, the 90 deg prevents lockup. I think it works best at low RPM, so it never really caught on in modern engine design, remember, this is 1889, and is designed by a pioneer in engine design. It might be noted, Forrests engines had spark plug ignition, something that had not caught on in mainstream engine design for another 30-50 years or so.

Hope this helps, Soon I'll be posting some pics of the mechanism.

maury
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Offline Dave Otto

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Re: Forest 1889 6 cyl Marine Engine
« Reply #37 on: May 29, 2021, 08:08:28 PM »
Here is one in motion if interested.

Dave


Online crueby

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Re: Forest 1889 6 cyl Marine Engine
« Reply #38 on: May 29, 2021, 09:24:28 PM »
Crueby, thanks for tuning in, and the question.

As with most things, there are probably other names for a Lee Shaft.
A Lee Shaft is made up of two rods tied to two cranks ofset by 90 deg. The shafts are tied to cranks of the same dimensions on both ends. The hafts c/c is equal to the of c/c between the shafts attached to the cranks. The purpose is to transfer motion from the driving shaft to the driven shaft. When one of the rods is pulling, the other is pushing, the 90 deg prevents lockup. I think it works best at low RPM, so it never really caught on in modern engine design, remember, this is 1889, and is designed by a pioneer in engine design. It might be noted, Forrests engines had spark plug ignition, something that had not caught on in mainstream engine design for another 30-50 years or so.

Hope this helps, Soon I'll be posting some pics of the mechanism.

maury
Ah - think I have a mental picture of that. Sounds like an interesting way to avoid needing sets of bevel gears to offset the shaft, simpler parts giving the same result. Thanks!

Offline maury

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Re: Forest 1889 6 cyl Marine Engine
« Reply #39 on: May 30, 2021, 03:54:30 PM »
Dave, thanks for the video. It shows how the Lee Shaft works well.
Is that your engine? I remember you getting castings from me many moons ago.

maury
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Offline Dave Otto

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Re: Forest 1889 6 cyl Marine Engine
« Reply #40 on: May 30, 2021, 05:17:19 PM »
Hi Maury
That is Max's engine, I haven't started on mine yet.

Dave

Offline maury

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Re: Forest 1889 6 cyl Marine Engine
« Reply #41 on: May 30, 2021, 06:36:11 PM »
Dave, tell Max he did an excellent job on it. It's good to see a working one out there.
maury
"The trouble with socialism is that you eventually run out of other people's money."... Margaret Thatcher

Online crueby

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Re: Forest 1889 6 cyl Marine Engine
« Reply #42 on: June 05, 2021, 12:12:37 AM »
Crueby, thanks for tuning in, and the question.

As with most things, there are probably other names for a Lee Shaft.
A Lee Shaft is made up of two rods tied to two cranks ofset by 90 deg. The shafts are tied to cranks of the same dimensions on both ends. The hafts c/c is equal to the of c/c between the shafts attached to the cranks. The purpose is to transfer motion from the driving shaft to the driven shaft. When one of the rods is pulling, the other is pushing, the 90 deg prevents lockup. I think it works best at low RPM, so it never really caught on in modern engine design, remember, this is 1889, and is designed by a pioneer in engine design. It might be noted, Forrests engines had spark plug ignition, something that had not caught on in mainstream engine design for another 30-50 years or so.

Hope this helps, Soon I'll be posting some pics of the mechanism.

maury
Ah - think I have a mental picture of that. Sounds like an interesting way to avoid needing sets of bevel gears to offset the shaft, simpler parts giving the same result. Thanks!
It was perfect timing to learn about the Lee Shaft linkage, just saw one on an Allis pump engine in the Boston waterworks museum, has the two cranks, 90 degrees offset, one at either end of the engine to drive the shaft with the valve eccentrics. Without your description I wouldn't have noticed what it was or how it works.   :ThumbsUp:

Offline kvom

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Re: Forest 1889 6 cyl Marine Engine
« Reply #43 on: June 05, 2021, 11:59:12 AM »
So today you'd just have a belt or chain between the two?

Offline Dave Otto

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Re: Forest 1889 6 cyl Marine Engine
« Reply #44 on: June 05, 2021, 05:52:11 PM »
Hi Maury
I'm curious where you came up with the name Lee shaft, Google seems to return nothing?

Dave