Bog's Paddleduck Engine

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Darren:
I've done 11 of them :)

Only 63 to go, see nearly finished :lol: :lol: :lol:

bogstandard:
Just to make a bit of a suggestion.

You don't need to go too tight on your tolerances. If you can do it, then great, but it is not absolutely necessary. The engine was designed with a beginner in mind that wouldn't be able to hold fine measurements and fits, so adjustments are in there to help with, and cure any problems. Plus as they gain more experience and confidence during the build, they will start to get better at making tighter tolerances.
I am not talking about being sloppy, but if the bits fit together without too much rattle, then it will run.

The critical bits are the spools in the steam chest, the piston to bore and the spool in the control valve.

Bogs

kvom:
I have just started learning to bore on the mill, so trying to "hit the number" was a challenge that I didn't need here, as you say. For the next one I'll likely save some effort and go for a looser fit.

I had some distractions today, mainly fixing up a new bicycle for one daughter. With the shop time I had this afternoon, and knowing the number of parts to be made on the mill, I decided to cobble together a vise-stop.

At school I made a clamp-type stop that clamps to the fixed jaw of a Kurt vise. However the jaws on a Bridgeport vise are slanted, so I can't use it. I do plan to replace this vise with a Kurt, as a friend just bought a BP with no vise and has agreed to buy mine. In the meantime, I made this one out of a few pieces of steel I had lying about:

Should be OK for the shortterm.

Bernd:
kvom,

I'll bet you'll keep that one around fro sometime to come. :)

Did you tap all the way through that block or do you have a nut on either side?

Bernd

kvom:

--- Quote ---Did you tap all the way through that block or do you have a nut on either side?

--- End quote ---

The round shaft is 5/8" diameter. I used a 5/8" end mill to cut a pocket 2/3 of the way through the plate. On the bottom is a hole for a 1/4-20 flat-head screw that is countersunk. I drilled and tapped the bottom of the shaft to accept the screw.

There is a jam nut on the other side of the threaded rod; that hole isn't tapped.

I used the stop after dinner to make the other eccentric strap. It definitely saved time, as I was able to finish it in about 2.5 hours. I also used the abs/incr feature of the DRO for the first time. I set the abs (0,0) coordinate to the stop and the fixed jaw, but then I was also able to switch to incr mode without losing that abs coordinate. Once I had the abs dialed in, I needed to use the edge finder only once more, so find the center for boring (I could have calculated it, but wanted it to be exactly on the seam).

This time I bored it .004 over the eccentric groove and it turns very freely. I still need to drill the two holes though, and also drill and tap the holes for the setscrews on the eccentrics.

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