Gallery, Projects and General > The Design Shop
An experimental engine
sbwhart:
Good work on fixing the wheels to the axles looks a real neat job :thumbup:
Stew
Stilldrillin:
It's beginning to take shape now Arnold! :clap:
I'm looking at the last pic, and visualising it with the motion rods in place..... :D
Good luck! Keep it coming.....
David D
Rob.Wilson:
:D :D :D :D :thumbup: lookin good mate :ddb: :ddb: :ddb:
Rob
arnoldb:
:beer: - Thanks Gents, I appreciate the comments!
Today's bit...
I used the stop hole in the arbour with a pin shoved in to set the depth for each axle, and then locked and fed the carriage from the feed screw hand wheel. When the first axle was to length, I took a note of the reading on the feed screw hand wheel. The other axles was then finished to this same reading to get the lengths correct:
Obviously, the pin was removed from the hole after the axle was tightened down with the set screws, and before switching on the lathe.
More drilling and tapping and countersinking followed on the end of each axle as well. Then it was off to the mill to mill the key slots; 1.5mm wide and 0.75mm deep. Both sides of each axle was done in one setting to keep the slots in line:
Then cleaned off the burrs from milling the slots (that old 1.5mm cutter seems to have had it now; I should have used a new one!) and cut 6 countersink M3 screws to length to use on the axles & wheels:
Well, what do you know; they actually fit the track with just the right amount of side-play ;D:
Assembled on the frames, and a shot from above on a 27" curve (the sharpest for O gauge - and meaning a curve taken from a circle which would have a diameter of 27") - and the reason for the blind drivers in the middle; as you can see, they are way off the track, yet the other wheels still follows the curve quite easily if pushed along:
Next come the fun bits; the drive train and valve gear. I'm really looking forward to that!
Regards, Arnold
arnoldb:
Earlier this week, I finished tapping the crank holes in the wheels. Just clamped all the wheels on the tooling plate with the holes to be tapped located over tooling holes and manually tapped all the 3mm holes:
This afternoon I started off with two strips sawn from 2mm thick brass plate:
These were then cleaned fairly well on one side each, and a thin strip of soft solder placed on one:
The other was placed on top, and I just used a plumber's torch to heat them up and solder them together.
The strips were then cleaned up and milled to 6mm width and a clean reference end. I marked for a center hole next to the reference end, and didn't bother to mark the rest; I'd do them by the dials. The workpiece was clamped to the tooling plate on top of a strip of aluminium plate (got that from an old QUICK-80 tape of which I now have a whole stack) Then I centered the mill on the reference:
And then drilled three 3.2mm holes in it at the same spacing as the axles. I only needed 3mm holes, but made the holes slightly larger to allow for slight variations in wheel positioning, as well as to allow a bit of pivot in the holes once mounted, as the wheels can move from side-to-side by about 0.8mm:
That would have been all that was needed for the experimental engine, but I got a bee in my bonnet and decided to try and be a bit flashy for a change, so I tried out my new 4mm ball nose mill - just 0.6mm deep into the brass:
Just couldn't leave things at that, so I took away a bit on the sides as well:
And ended up with this lot:
Just had to try and keep my filing skills in shape, so filed the pointy bits approximately round, and then re-heated with the blow torch to separate the two pieces. Then spent a couple of minutes to remove the solder from the back sides with some emery paper. Net result:
Can anybody spot the booboo I made ?
At least the booboo is visual and not mechanical; the rods fits nicely on the wheels, and there is no sticky bits when rolling along the rail. I still need to make up some proper mounting screws and spacers though:
Regards, Arnold
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