Author Topic: 1 eight scale 3HP buffalo marine twin  (Read 27504 times)

Offline b.lindsey

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #15 on: December 14, 2014, 01:34:02 PM »
Beautiful work Mike...I love the little gearbox. I am following along even if quietly.

Bill

Offline Don1966

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #16 on: December 14, 2014, 03:47:49 PM »
Hi Mike just catching up on you built and I have to say you are doing some excellent work. Just love the gear box and working with brass is one of my loves. I will be following along to see some of your fabrication work. ............ :ThumbsUp:



 :popcorn:
Don




Online mike mott

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #17 on: December 15, 2014, 05:29:23 PM »
In order for the gearbox to be able to lock so that the prop rotates forward there is a clutch that is splined, I have been wracking my brains working at finding a way to make a small spline. This morning as I woke up it hit me.



Yup the trusty old allen head cap screw has a negative hex to accept the hex key, I matched up a 5/16 cap screw with some 1/4 inch hex brass. the steel collar will revolve in the base of the forward/reverse lever and will move about 1/64 to clamp the prop shaft to the gearbox causing the forward motion. the hex part will be pinned to the prop shaft, and a loose clamping collar will be inserted between the hex collar and the casing of the gearbox, when the lever is pulled back the hex collar will move forward clamping the case and loose collar hence locking the case to the prop-shaft





The revers is accomplished by clamping the gearbox inside a steel band which was made from some steel rings turned up and silver soldered together. As the gearbox is clamped the splined collar also releases the loose clamping collar allowing the gears inside to impart the reverse








When I cut the slot on the top of the band it automatically sprung to a smaller diameter which works in my favour because in order to open the band a wedge has to slide forward, this wedge is connected to the forward reverse lever.



Mike




If you can imagine it you can build it

Offline smfr

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #18 on: December 15, 2014, 05:32:47 PM »
This is a very intriguing build, Mike. It's interesting to see the gearbox come together  :ThumbsUp:

Simon

Offline Dan Rowe

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #19 on: December 15, 2014, 06:30:59 PM »
Very nice Mike,
Another source for a small spline is a cheep socket. I was wondering how the controls on the reverse was going to work nifty solution. Did the original reverse gear work with a similar method?

Dan
ShaylocoDan

Online mike mott

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #20 on: December 15, 2014, 07:26:12 PM »
Simon, thanks
Dan yes the original used a set of clutch plates to do the same things as well as the band clamps, each manufacturer had a slightly different way of doing things. see this link http://babel.hathitrust.org/cgi/pt?id=mdp.39015002071820;view=1up;seq=343

and this page 

http://babel.hathitrust.org/cgi/pt?id=mdp.39015002071820;view=1up;seq=345


It describes the way these reverse gearboxes functioned. I have been using this document to help sort out my own gearbox, i had to make changes because of the small size I am working with and because I am not a watchmaker, I had to use other ways.


Mike
If you can imagine it you can build it

Offline Roger B

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #21 on: December 15, 2014, 08:23:31 PM »
I do like your spline solution  :ThumbsUp:  :ThumbsUp: I think that I have seen a picture in Hiscox's book of a reversing gearbox with a bevel gears and clutches that used the propeller shaft thrust to keep the clutches engaged.
Best regards

Roger

Online mike mott

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #22 on: December 16, 2014, 05:41:15 AM »
Today I made the actuating lever to open and close the clamp ring, the lever is wedged so that in the closed position the width across the flange at the bolt is .250" and when open the the width is .290"





here is a video of the way it works.



Mike
If you can imagine it you can build it

Offline Dan Rowe

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #23 on: December 16, 2014, 03:51:54 PM »
Nice work Mike, thanks for the drawing links.

I had to check what the hex hole things I bought a few years back were called. If you need a long hex hole look for steel hexagon sleeves. Here is an example:
http://www.sdp-si.com/web/html/newprdrsleeves3.htm

Dan
ShaylocoDan

Online mike mott

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #24 on: December 16, 2014, 05:56:23 PM »
Dan thanks I had forgotten the name of that company, many years ago I had their catalogue.  looks like they have greatly expanded their range of products.

mike
If you can imagine it you can build it

Online mike mott

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #25 on: December 17, 2014, 10:15:32 PM »
I realized that the tabs were too narrow to hold the clamp ring so made a new one from a solid ring which required a fair bit of milling and hand filing.







Also made a flywheel from some free machining bar stock.





Getting the clamping to work smoothly has required a lot of fiddling with the diameter and the flexing of the clamp ring.



mike
If you can imagine it you can build it

Online mike mott

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #26 on: December 18, 2014, 04:11:01 PM »
I worked on the clutch yesterday, first I made a hex broach to form a 3/16 hex spline in some brass stock the end of the full end broach was reduced so that as the broach was pushed through I could part off the discs.







next a few thin plates of mild steel for the slip rings these were drilled first then parted off the steel discs are .630" x .020" thick the brass ones .345" x .030" thick. the steel discs with be fixed to the gearbox and the brass disc will be fixed to the prop shaft via the hex collar on the shaft the large collar will act as the pushing element



test assembly



Mike 
If you can imagine it you can build it

Offline Roger B

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #27 on: December 20, 2014, 04:32:31 PM »
That's some very neat work on the gearbox  :ThumbsUp:  :ThumbsUp:
Best regards

Roger

Online mike mott

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #28 on: December 20, 2014, 05:35:34 PM »
Roger thanks for your kind comment.

I am making the lever control now that the rest of the clutch parts are installed.







Michael
If you can imagine it you can build it

Online mike mott

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Re: 1 eight scale 3HP buffalo marine twin
« Reply #29 on: December 21, 2014, 05:00:38 PM »
Using a hardened button file guide to file the diameter and  bosses on the lever.







The top of the handle is filed because I was unsuccessful turning it in the four jaw chuck, it snagged on the tool and bent so after straightening it i cleaned it up with needle files and steel wool.



Two more links and then to test the clutch.

Mike 
If you can imagine it you can build it