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Post by kvom on Nov 18, 2010 16:44:43 GMT -5
Thanks for the photo of the setup on the drillpress. The idea of used the bumper holes as a drill jig is also good. I was originally doing to drill all the holes in the frame on the CNC mill, but since my table X range is a bit short, I think doing it all on the BP makes sense as it's a single setup for each side (and I have a DRO  ) |
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Post by kenrinc on Nov 19, 2010 16:37:20 GMT -5
Word! I've sort of backed off on my project until I finish putting scales on my Mill. I feel I will make much more headway faster once I get these installed as setting up the mill for cuts is half the time of any job.
Ken-
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Post by kenrinc on Jan 24, 2011 14:24:55 GMT -5
Making some progress on my A3   Got the valve rod, valve, piston, piston rod and bushings done and working well. Left cylinder didn't work quite right. Either the head piston hole is out of center or the bushing is as the piston hits the wall at some point. I'll redo the bushing first since it's less work. Ken- |
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Post by kvom on Jan 24, 2011 22:40:49 GMT -5
Looking good. I got my spring leaves cut out today and will be drilling them tomorrow. How did you cut the slots in the ends of the top two leaves in each pack?
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Post by phutcheson on Jan 25, 2011 12:17:22 GMT -5
Ken,
Nice looking ..
Are you using O-rings? I had a similar problem with my piston jamming a little in the cylinder. I re-chucked the Piston and Rod in a 5c collect, turns out that they were not concentric. So I turned down the piston a little. In reading about O-rings and the clearance between Piston and Cylinder ... can be more.
Keep up the nice work. 
Pat H.
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Post by kenrinc on Jan 25, 2011 14:16:07 GMT -5
kvom: I drilled two outer holes then milled between them with a carbide end mill but my machinist buddy told me I could have just as well just milled the entire slot with the end mill. Spring steel is hard but not that hard.
pat: I'm using O-rings but only for the rod packing. I'm using piston rings. I take back what I said about the Orings as I think I was looking at it the wrong way. Time will tell as I won't be running on air for awhile. My problem is the piston rod is not concentric with the cylinder bore. That could be the rear head or it could be the bushing. My guess is it's the bushing, at least that's the easiest thing to check first. I'll make a new one and check. The other cylinder turned out beautiful; silky smooth.
I did the same as you, as my piston was not concentric either. Real locomotives had up to a 1/2" total clearance on pistons so I can't see how .010" makes any difference ;D
Ken
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Post by kvom on Jan 25, 2011 17:01:31 GMT -5
On the small models I've made previously I always tried to turn the piston attached to its rod, so It was guaranteed to be as concentric as the collet the rod was chucked in. I plan to finish turn the pistons in that way. In any case, I'll be interested in what you find out.
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