Author Topic: Muncaster Grasshopper - Work in Progress  (Read 22437 times)

Offline crueby

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Re: Muncaster Grasshopper - Work in Progress
« Reply #180 on: January 01, 2019, 01:45:40 AM »
Very nice result! Thats one of those parts where I would stop and go: lets see, turn THAT face up, no, wait, THAT one... Or...
 :popcorn: :popcorn: :popcorn:

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #181 on: January 01, 2019, 02:29:15 AM »
Only 3 turns needed here.  I put all three views in the same DXF, which allowed me to make sure all were aligned properly.

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #182 on: January 01, 2019, 10:17:50 PM »
Machined the other, simpler part of the bracket today.  The arm still needs a fixture to finish rounding the end.



Offline Ye-Ole Steam Dude

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Re: Muncaster Grasshopper - Work in Progress
« Reply #183 on: January 02, 2019, 08:49:18 AM »
Hello kvom,

That is some beautiful work.

Have a great day,
Thomas

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #184 on: January 06, 2019, 12:50:10 AM »
My gears arrived on Friday, so it was time to get back on the governor.  First was to clean up the "arm" of the upper bracket where it was attached to the parent stock.  Here's the setup I used on the CNC mill.



I used Loctite 620 to attach a short length of 5/16 drill rod; then clamping in the machinist vise's v-slot ensured it was vertical.  Then a series of slow 180-degree passes removed the unwanted portion.  Afterwards I put the assembly in a 500-degree oven for half an hour, then used my arbor press to remove the rod.

Then a test fit of the two gears to the lower bracket while still attached to the bar.



I removed some bracket material with the side flutes of an endmill until the pinion shaft looked vertical.  This may need to be done again once I have the upper bracket in place with a full-length shaft.  But for now I could saw off the bracket and face mill off the saw marks.

Neither of the gears had set screws, so it was necessary to drill and tap 8-32 on the larger gear.  I did this with a piece of 3/16" brass rod inserted to avoid burrs on the bore.



With the bracket attached to the engine's base, I can start to do some more fitting.



As I mentioned in a previous post, a follower is needed on the crank pin to drive the gear train.  To make this I started by carefully turning some half inch brass rod down to 7/16 (0.4375).  Then I drilled some 3/8" drill rod and reamed to .4365.  Both the brass and the edge of the hole had a slight chamfer.  Then I used my arbor press to join the two.  After drilling and reaming the brass 5/16", I faced both ends to length.



Then I drilled and tapped a cross hole 5-40 for a 1/8" rod.  Together with the spacer seen below, turning the crank now also turns the gear:



The drive rod needs to be shortened and the spacer cleaned up, but I'm happy with the results thus far.

Offline crueby

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Re: Muncaster Grasshopper - Work in Progress
« Reply #185 on: January 06, 2019, 01:03:35 AM »
All that CNC and you didn't cut the gears?


 :stickpoke: :stickpoke:    :Lol:

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #186 on: January 06, 2019, 02:55:06 AM »
I cut a check.  Does that count?  :shrug:

Online Kim

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Re: Muncaster Grasshopper - Work in Progress
« Reply #187 on: January 06, 2019, 05:33:17 AM »
I cut a check.  Does that count?  :shrug:
Apparently it does count!  You've got the gears, and they seem to be doing the job!  :Lol:
Kim

Online b.lindsey

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Re: Muncaster Grasshopper - Work in Progress
« Reply #188 on: January 06, 2019, 01:00:55 PM »
Very interesting governor mechanism Kirk and should add a lot of interest to the model too. Still watching along.

Bill

Offline Admiral_dk

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Re: Muncaster Grasshopper - Work in Progress
« Reply #189 on: January 06, 2019, 10:09:23 PM »
Great result Kirk + it will make people take a second look when it is running  :ThumbsUp:

Offline Craig DeShong

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Re: Muncaster Grasshopper - Work in Progress
« Reply #190 on: January 07, 2019, 09:45:14 PM »
Impressive work; I was wondering how you were going to make that bracket.  Thanks for the step photos.  :cheers:

Following along  :popcorn: :popcorn:
Craig

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #191 on: January 27, 2019, 03:39:48 PM »
I've been laid up with a pulled muscle in my back since Thursday, and have been playing with generating STL models of some gears.  I loaded one of them into Shapeways and notices that the upload of an STL file created in metric needs to be specified as inches to get it sized correctly.  I went back and looked at the governor bracket that seemingly couldn't be printed now is possible once properly resized.  Still not cheap and 10 days to deliver.

The wheel gear I modeled is about the same size as the one I ordered from SPI, and printing in brass would be similar cost.  In steel about half price.

Offline crueby

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Re: Muncaster Grasshopper - Work in Progress
« Reply #192 on: January 27, 2019, 04:04:34 PM »
I've been laid up with a pulled muscle in my back since Thursday, and have been playing with generating STL models of some gears.  I loaded one of them into Shapeways and notices that the upload of an STL file created in metric needs to be specified as inches to get it sized correctly.  I went back and looked at the governor bracket that seemingly couldn't be printed now is possible once properly resized.  Still not cheap and 10 days to deliver.

The wheel gear I modeled is about the same size as the one I ordered from SPI, and printing in brass would be similar cost.  In steel about half price.
I noticed the same thing on Shapeways recently when I uploaded some parts for an engine, they came out tiny till I resized them, no change to dimension but clicked on inches. They seem to be ignoring the inch/metric button till after the file is loaded.

Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #193 on: January 29, 2019, 10:39:58 PM »
Continuing on with governor parts as time allowed over the past two weeks.  The pivot was a particularly tricky on, and I had to scrap three of them before getting a useable part.  First op was profiling from a piece of 2x1x1" brass bar to get two parts.



Then turning 90 degrees, mill out the open pocket.



Then relieving the "arm" on the opposite end.



After cutting the two pieces apart, the remaining op is to remove the remaining stock where the part is still attached.  Because the part is difficult to chuck in a regular vise, I decided eventually to machine a set of soft jaws.



Then I moved the jaws to the Bridgeport and face milled gently.



Finally a family shot of parts made to date:


Offline kvom

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Re: Muncaster Grasshopper - Work in Progress
« Reply #194 on: January 29, 2019, 11:10:06 PM »
A part I'd done previously and forgot to show.  The lower sliding collar of the governor.  Again, using 1x1" brass bar, the profile is machined into the end of the bar.



Next, a 3/16" hole is drilled halfway through the bottom and reamed.



On the top, a center drill is used.



After sawing the piece free from the stock, one can see how the part will be able to be turned in later ops.  But next, the bottom is milled round.



And the reduced neck is turned with a parting tool.



After this, the top is milled to correct width and a length of 3/16" drill rod was loctited into the bottom.  After curing for over a week, the piece was back on the lathe with the drill rod help in the collet check and supported by the live center.  This allowed the slot to be turned in the bottom portion to fit the arms of the pivot (can be seen in the family shot of the previous post).

Now the problem is to remove the drill rod and finish drilling and reaming through the entire part.  I put the assembly in a 500F over for an hour, but it didn't release.  Fiercer methods were called for, and with the drill rod clamped in the bench vise I heated it all with the torch.  It was very surprising when the part flew into the air with a POP!  It seems that there was a pocket inside with some unsolidified loctite that boiled, creating enough pressure to blow it off.