Author Topic: Lauson LA build  (Read 17950 times)

Offline Craig DeShong

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Lauson LA build
« on: January 08, 2018, 12:19:49 AM »
I haven’t really started this build yet; might not even pursue this much further depending on potential problems I could encounter during the design but I thought I’d start this post and name it so that if the build proceeds, everything can be together.

I usually start a new design around this time of year, with the shop so cold that getting work done out there is out of the question.  I have lots of time to think about a new potential project and start working out the details.  There is a tremendous amount of design work that goes into one of these models even though they are “scale” models of full size engines.




Above is a view of the full size engine I plan to model; the topic of this post/thread.  I suspect most of my readers aren’t familiar with Lauson products.  The Lauson LA is a single cylinder air cooled small engine that Lauson built in the early 1930’s.  It has a bore and stroke of 2 ½ x 2 ½ inches.  The camshaft rides on a mandrel and is driven by helical cross gears off the crankshaft, a flyweight governor attaches to the rear of the camshaft to control the throttle of the Tillotson float carburetor.  The engine incorporates an oil pump, pumping oil into a dipper trough for splash lubrication and it has an interesting kick start mechanism.  All this I plan on modeling. 
The model will be built at ½ scale, which will result in a model that stands around six inches tall, about the same height as the Lauson TLC I built a few years ago.  The engine incorporates a Wico type FG flywheel magneto, and I’m toying with the idea of building this magneto in scale (as opposed to using battery/coil as I have with my other Lauson models).

The frigid temperatures of the past week have provided me with lots of time to begin the design.  Following are a few CAD images of the design do far.





As you can see, the design of the block is fairly well along.  I started cheating on some of the finer detail at the top of the block because the whole top of the engine is covered in sheet metal as you can see from the picture of the full size above.

Lastly, I’ll give you an exploded view of the block components.  This block would be difficult / impossible for ME to fabricate as one piece (no castings in this model) but I think I can manage the shown parts and then fit them together.


« Last Edit: March 06, 2019, 01:48:34 PM by Craig DeShong »
Craig

Offline b.lindsey

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Re: Lauson LA build
« Reply #1 on: January 08, 2018, 12:36:35 AM »
Looks great so far Craig!! I can sympathize with the cold temps, wasn't able to do a thing in the shop this weekend. Good this to do design work inside where it's warm as you say. Will be following along.

Bill

Offline crueby

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Re: Lauson LA build
« Reply #2 on: January 08, 2018, 02:45:01 AM »
Very interesting looking engine. What were the originals used for, typically?

Offline Craig DeShong

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Re: Lauson LA build
« Reply #3 on: January 08, 2018, 03:35:26 AM »
It's a 85 lb. 2HP, 2000 RPM engine.  I'd assume it could run a pump, any number of farm equipment, concrete mixer; anything a stationary engine of 2 HP might power.
Craig

Offline 10KPete

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Re: Lauson LA build
« Reply #4 on: January 08, 2018, 04:51:50 AM »
All the early Maytag washing machines had a little engine like that. The Lady could step on the pedal to start it!

Modern conveniences...

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Craig DeShong

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Re: Lauson LA build
« Reply #5 on: January 08, 2018, 04:40:16 PM »
Lauson Built model types RA and RAB; these were 1/2 HP washing machine engines.  I've never seen either, and only have a picture of a RA from a Lauson catalog.  This LA is a bit larger at 2 HP; built as a general purpose engine I suspect.

Pete: Grandmother had a gas powered Maytag she kept in the spring kitchen back on then farm.  She said she always got "Pop" to start it for her though!
Craig

Offline Craig DeShong

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Re: Lauson LA build
« Reply #6 on: January 18, 2018, 08:42:48 PM »
I got back from the Cabin Fever Modelers Expo and another cold winter week afforded me some time to continue the design on this new model.  The design seems to be coming along pretty well.

I had a warm day or two to experiment in cutting the helical gears I’ll need for the construction of this model.  The results weren’t exactly ready for usage but I’m hoping I can make a few changes in the procedure and end up with serviceable gears to drive the camshaft as well as operate the petal start.

A view from the top-rear of the block.  The governor cover and PTO bearing cover are yet to be designed/drawn.



A view looking into the bottom of the block.  A base needs to be designed and drawn yet but you can see the camshaft with cams and drive gear in place.

 

Same view as above, looking in through the PTO bearing opening.  The full size uses tapered roller bearings but I'm opting to just use ball bearings for the crankshaft as I have in my other Lauson models.



One more view from the front of the engine block


I have many drawings to complete yet, but the design seems to be coming along nicely.  This engine should be a fun project to build.
« Last Edit: March 06, 2019, 01:53:00 PM by Craig DeShong »
Craig

Offline Dave Otto

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Re: Lauson LA build
« Reply #7 on: January 19, 2018, 12:10:55 AM »
Good progress Craig,

Are you planning to silver solder the block components together? It will be fun to watch this one come together.

Dave

Offline Craig DeShong

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Re: Lauson LA build
« Reply #8 on: January 19, 2018, 12:22:09 AM »
Thanks Dave.  The first post identifies the block parts that need assembled to make a complete block.  I used JB Weld on the VR ( previous model) with great success.  I'm thinking of JB Weld again with this model, along with strategically placed strews and set screws to assist the glue.  Silver solder is not an option since the block will be mostly aluminum.
Craig

Offline gbritnell

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Re: Lauson LA build
« Reply #9 on: January 19, 2018, 01:05:08 PM »
HI Craig,
If I might ask how are you making the helical gears? I have a video posted on YouTube from when I made my helicals and they seem to work fine.
gbritnell
Talent unshared is talent wasted.

Offline Craig DeShong

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Re: Lauson LA build
« Reply #10 on: January 19, 2018, 02:10:33 PM »
I just KNEW somebody was going to ask that.  I searched youtube and I believe I’ve found the video you mention.  If it is, you’re using a jig you build from a drawing by “Chuck Fellows”.  I’d be interested in more information on this jig.  Would you tell me where I might find the drawings?

I have experience cutting spur gears with my Bridgeport, dividing head, and involute gear cutters, no experience with helical gears.  Both helical gears I’m trying to cut will have teeth at a 45 degree angle.  I’m looking at gears with a diametrical pitch of 24, one with 13 teeth and the other with 26.  Both gears will be ¼ inch in thickness.  The traditional way of doing this is to lash your dividing head to the X mill table travel, so the gear blank is rotated as X axis table travel passes it through the cutter.  Unfortunately, my dividing head has no such ability. 

Since the gears I’ll be cutting have a tooth profile that is more “spur” in character than “worm” (due to the thinness of the gear), I’m thinking (?) that I can approximate the above method as follows:

Place my rotary milling head on the Bridgeport spindle and rotate the mill head until its spindle is parallel to the table.  Place the gear blank in my dividing head and place the dividing head at a 45 degree angle on the mill table.  Use the rotary milling head to cut an arc around the gear blank, forming a helical gear tooth as I would normally use the Bridgeport Y axis to form a spur gear tooth.  Theoretically, this arc, cut around the gear blank by the rotary milling head, should be elliptical in nature but for the relatively short arc I’m using, I’m hoping the circular path the rotary milling head will follow will suffice.  Initial trials appear to be promising.

I’ve posted a picture of the first attempt.  I believe I had the gear blank a bit off-center as the gear teeth aren’t quite symmetrical; the cutter may have also been set a bit too deep.  Additional attempts are being held-up by the inclement weather and an un-heated shop.  I’m curious to get both gears cut and build a fixture to hold them so I can assess how well this technique will (or won’t) work.

I was planning on posting all this if it worked out, still will if it does.  It would be nice to have a “plan-B” and the jig-fixture you describe might be the solution. 
I can buy the gears I need at 15 and 30 teeth, but I’d need to change my drawings.  What fun is that? I’d rather cut my own gears.
« Last Edit: January 19, 2018, 02:17:00 PM by Craig DeShong »
Craig

Offline gbritnell

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Re: Lauson LA build
« Reply #11 on: January 19, 2018, 08:35:30 PM »
Talent unshared is talent wasted.

Offline Craig DeShong

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Re: Lauson LA build
« Reply #12 on: January 19, 2018, 10:14:00 PM »
Thanks, I'll take a look.
Craig

Offline Craig DeShong

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Re: Lauson LA build
« Reply #13 on: January 29, 2018, 07:20:34 PM »
As I stated in a previous post; without helical gears this project is going nowhere.

I’ve been quiet on this thread for a while, but I have been busy: studying helical gear mechanics.  Taking the suggestion provided in the above post by “gbritnell” (thanks ever so much!) I’ve been watching a few Youtube videos provided by the member above and by a Mr. Chuck Fellows, building and testing the helix gear cutting fixture as described in the above thread’s link, and making a few gears.  Things haven’t gone silky smooth; mostly due to a 3rd grade arithmetic problem I kept overlooking   :facepalm2:  but at this point I believe I have a handle on cutting helical gears, at least well enough to proceed with this project.

What I show you is my “proof of concept”; it proves to me that I have all the theory and math right, and that my helical gear cutting fixture can be depended upon to cut accurate gears.  These “proof of concept” gears were fabricated with aluminum; no use wearing out expensive gear cutters on gears you don’t plan on putting into service, though I did cut one steel gear- just to see how this fixture works with a tougher material.

Based upon what I’ve learned I’ve decided to change the Diametral Pitch I’ll be using on the gears that mate the crankshaft to the cam shaft, as well as the helix angles of these two gears.  I used involute gear cutters I had on hand for this “proof of concept” but I will need to purchase two involute cutters with a larger Diametral Pitch.  If my math is right I can use a Diametral Pitch of 32; with the crankshaft gear having 12 teeth and a helix angle of 60 degrees while the camshaft gear would have 24 teeth and helix angle of 30 degrees.   This should provide a spacing of .808 inches between the two shafts, close to a scale distance.

I’ve provided three pictures:  Two of my gear cutting fixture, adapted from Chuck Fellows drawings; the third is my “proof of concept” with the two gears I fabricated mounted in a holding jig to verify their correct mating.
Craig

Offline Craig DeShong

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Re: Lauson LA build
« Reply #14 on: January 31, 2018, 02:05:27 AM »
Another cold day and another opportunity to stay inside and work on this engine design.  I made the few changes to the block I needed to make in order to accommodate the correctly sized helical gears on the crankshaft and camshaft and then I re-drew both gears.  As you can see I’ve added the crankshaft with the gear that drives the camshaft to the block assembly

This is my first attempt at using this 3-D CAD software, though I’m still relying on my old drafting software to keep some of the numbers straight.   It has its unique difficulties (possibly due to my learning as I go) but all in all it is really turning out to be a great design tool and I can see the engine going together as I design the individual parts, combine them into sub-assemblies, and then into the final assembly.
Craig