Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Lathe is all back together - feels a little better now.



I've been reorganizing as well - moving some of my raw material off the wooden shelves, and sorting out tool storage there. Still got to do the lower shelf.

With the lathe back together I made some progress on the cylinder.

I mounted it on the angle plate. I used a 1-2-3 block as a stop, and made sure that was parallel to the table, then repeated the parallelism check on the face of the cylinder once I had it clamped in place.



I used an edge finder to find the center of the high edge of the bore, and then after a little trigonometry calculated the position of the centers of the two port holes, and spot faced them with a 1/8" end mill, then drilled down to the slot that was previously milled in the steam chest.





I am pleased that I hit the slots dead on - right at each end of the slot. It was a real fulfilling sense of achievement when I felt the drill break thru into the slot.

Now to turn it over and repeat on the other side. This part is actually close to completion! I hope to drill the other ports tomorrow, and do a little more turning on the inboard head.

I drilled the other two port holes today, but got them off center. They will still work, but I'm getting a bit tired of making parts "that will still work". Not sure where I went wrong - whether it was in finding center or if I just indexed too far when moving to the drill point. I'm not even going to post pictures, too embarrassing. I might go ahead and buy a new casting, on the basis that implementing what I've learned on the first one will make for a really nice second one, however I shall be extremely disappointed if I have to replace every casting in the kit.

Which brings me to my second issue of the day, and a real disaster.

I picked up the inboard head again, and was having a good time with it. I cleaned it up, got all diameters and faces true, and even drilled and reamed the through hole.





Then brought the disc to final thickness.



Got a lovely finish on it, and the thickness within .001" of dimension from the print. Great!

Proceeded to turn down the face some more to make the step, and that was going well, or so I thought, when suddenly my thickness measurements started moving around back and forth.........



Blast, and quite a lot of other words.

I don't really know how this happened. The part never grabbed, I was taking nice light cuts, everything seemed to be fine.

On top of that, I discovered while making this that there is still something wrong in the carriage of my lathe. The handwheel drive is not at all repeatable - go to move the carriage .020" - it moves .01 and change. Move it back down the bed and bring it back to zero, it ends up going past zero by .02" or more. So a key or a pin has broken in some gear or other in the saddle. I'll take that apart again before attempting to remake this.

At least organizing that area of the shop went well, and the cross slide adjustments worked well.

I'm not giving up. I'm going to finish this engine, and if I have to remake parts along the way, so be it.

Anyway, lathe is fixt. Found a sheared pin in one of the drive shafts.  :Mad:

Easy enough to fix, so that's something. And I have very quickly turned a piece of aluminium to replace the inboard head (not going to use the replacement casting just yet........). Will finish this after a bit of lunch.