Author Topic: Economy Model  (Read 8671 times)

Offline gbritnell

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Re: Economy Model
« Reply #30 on: January 15, 2016, 12:55:15 AM »
Great looking job on the gears. It's really one of those satisfying jobs and once you've done it you'll never buy another.
gbritnell
Talent unshared is talent wasted.

Offline mhirst121

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Re: Economy Model
« Reply #31 on: January 20, 2016, 08:00:47 PM »
Since I now had the gears made I decided to stick with the rear of the engine and make up the governor assembly. There are quite a few bits to this so I will update as more parts are finished, this is where I am up to at the moment.

Governor Mounting Plate.

This was machined from a piece of 10mm thick black plate, as thats what I had lying about. It was set up in the four jaw and one side faced true. The plate was then set up flat and square to machine the other side and to the finished thickness of 7mm.




Next it was over to the mill where two sides were milled square. Then using the DRO the various holes were machined and the final outline machined in.



The part was removed from the mill and the various holes tapped and countersunk where required, sorry theres no pics of this as photobucket will not let me upload them for some reason.

Governor Shaft

This was a simple lathe job, machined to size with a hole up the centre. The small gear is a press fit on the end and a little loctite was applied just in case.





shaft press fit on the end



Governor Bush

Again this was a simple lathe job and press fit into the plate.



Timing Gear and Cam Mounting Shaft.

This was turned and threaded M6 each end, a large flat retaining washer was also made and parted off to length.

Top Bracket

This was made from a piece of 6mm BDMS flat. It was marked out for the desired shape then mounted in the mill to drill the holes. Once the holes were drilled it was hacksawed out and machined to the lines. The radius was done by the pin method on the mill and finished with a file.

Marked out


Edge milled square and holes drilled using DRO for positioning


Cut from bar and recess milled in the end


Shape roughly cu out


Radius milled with pin method


Radius filed to shape and hole countersunk


Finished part fit to plate


More shortly
Cheers,
MartinH

Carlisle, Cumbria, UK
A creative mess is better than idle tidyness !!

Offline mhirst121

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Re: Economy Model
« Reply #32 on: January 20, 2016, 08:19:10 PM »
So this is where I was up to last post.



Next up was the cam. A blank was turned in the lathe. The profile of the cam was drawn out in a cad program and 36 equal radial lines put on it, then dimensioned for each line. This way I can set the cam blank up in the rotary table and feed in to the required dimension every 10 degrees. Once this is done I carefully file the edge of the can to the bottom of the cutter marks to give me a nice finished cam. I have done this on the lst couple of cams and they have turned out well. A pb bush was also fit to the bore of the cam once complete.

Blank mounted in rotary table chuck


The blank once it has been removed from the mill. You can see the high spots to remove to give the final profile. In the background is the drawing of the profile with the dimensions that I machine to.


The finished cam press fit in the timing gear with a little loctite


The next job was the arm that operates the detent lever. This was supplied as a casting, fettled and machined as per the drawing.

Arm cleaned up


Where it stands at the moment, gears line up fine and arm is in the correct position



Till the next time,

MartinH

Carlisle, Cumbria, UK
A creative mess is better than idle tidyness !!

Online b.lindsey

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Re: Economy Model
« Reply #33 on: January 20, 2016, 08:34:34 PM »
Thanks for the update Martin, those are some really nice looking parts and the cam turned out well also. Looking forward to more.

Bill

Offline Chipmaster

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Re: Economy Model
« Reply #34 on: January 20, 2016, 09:20:22 PM »
Impressive work Martin, with the progress you're making you'll have your engine running very soon.

Andy

Offline zeeprogrammer

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Re: Economy Model
« Reply #35 on: January 20, 2016, 10:06:05 PM »
Nice cam. And thanks for the how-to explanation.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Don1966

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Re: Economy Model
« Reply #36 on: January 21, 2016, 02:02:19 AM »
Great looking cam and is there anyway we can see your drawing of the cam profile? I would like to see how you went about doing it in cad.

Don

Offline mhirst121

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Re: Economy Model
« Reply #37 on: January 21, 2016, 03:14:48 AM »
I will try and load the picture of the cam profile later Don, and do a bit more explaining how I went about it. Photobucket was playing up earlier and the drawing picture would not load.
Cheers,
MartinH
Carlisle, Cumbria, UK
A creative mess is better than idle tidyness !!

Offline Roger B

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Re: Economy Model
« Reply #38 on: January 21, 2016, 10:22:20 AM »
Still following along  :ThumbsUp:  :wine1:

If you use the end rather than the side of an end mill for cutting the cam there is a lot less filling (or you could traverse the mill in the other plane to give flats rather than scallops)
Best regards

Roger

Offline mhirst121

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Re: Economy Model
« Reply #39 on: January 21, 2016, 03:07:13 PM »
Right I will try and explain how I done the cam, please note `I am not a CAD hero`, I normally just use a a pencil(old school you see). There are probably far easier and quicker ways to get to the required end result, but this is how I figured out how to do it.

If we have to make a cam with a large diameter of say 20mm and a tip radius of 6mm, the distance between the centres of these is 10mm. One flank has a radius of 30mm and the other a flank of 35mm.

In your favourite cad package draw a circle of 20mm dia.
Next draw another circle of 12mm dia.
Position these circle centres at 10mm apart. You should now have the two circles positioned the correct distance apart.
Next I draw a circle with a diameter of 60mm. I then move this circle to position it so that it intersects the sides of the circles already drawn.
Draw another circle of 70mm diameter and move this to intersect the first two circles on the other side.
I then use the trim function to trim all the unwanted lines to leave the profile of the cam required.
Draw a line from the centre of the first circle, well out past the radius of this circle.
Use the radial array function to equally space 36 of these lines about the centre of the first circle.
Once again trim these lines to the outside profile of the cam you have drawn.
You can then use the dimension tool to give you the length of each line.

This is what I end up with.


Hope you can follow this, I`m not very good explaining things on screen :facepalm:

Once this is done, I make up a blank slightly larger than the biggest radius then mount in the RT and plunge cut to the desired depth from the centre. The cam is then removed and the peaks filed down to the base of the troughs and that should be it, a nice cam.

Roger has pointed out a couple of good points above and i will try them out next time, thanks Roger.

Cheers,
MartinH

« Last Edit: January 21, 2016, 03:52:18 PM by mhirst121 »
Carlisle, Cumbria, UK
A creative mess is better than idle tidyness !!

Offline mhirst121

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Re: Economy Model
« Reply #40 on: May 18, 2020, 06:00:44 PM »
Well, I hope everyone is keeping fit and well. It has been a long while since I last visited this little project, been on with other things and never really had a lot of time in the workshop. I just thought a little update was in order to let you know how it is going.
I have nearly finished all the machining work, just a few small parts to finish off, then we can see if it will run.
Hope you enjoy and I promise not to get too distracted again and get on with a emptying a few of the boxes under the bench full of castings.
Bye for now,
MartinH
Carlisle, Cumbria, UK
A creative mess is better than idle tidyness !!