Author Topic: Steam Chest Drill Wrong  (Read 3556 times)

Offline jmccrack

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Steam Chest Drill Wrong
« on: July 28, 2015, 08:51:27 PM »
Hey Guys.
Need a hand. When I drilled the 3/32 hole in the steam chest on my Stuart 10V as you can see the guide hole in the back wandered. I have machine my eccentric rod and I can force it in but it is way to tight. I can drill the hole bigger so the shaft moves freely but what will that do to the sliding valve? OrI can drill everything bigger , sleeve them both and re drill.Thoughts?

Offline sshire

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Re: Steam Chest Drill Wrong
« Reply #1 on: July 28, 2015, 10:58:09 PM »
Machining other parts to correct a mistake is not a good idea. Each part has a function and tolerance. Once you start screwing around with parts to make them fix an error, other issues are bound to show up.
Plug the holes and redrill. Brass or bronze, press fit. Redrill.
Best,
Stan

Offline mklotz

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Re: Steam Chest Drill Wrong
« Reply #2 on: July 28, 2015, 11:19:07 PM »
Drill the first hole 3/32 and then use a 3/32 center drill to spot for the second hole.  If you don't have that size center drill use a transfer punch  or, failing that, put a point on a bit of 3/32 drill rod.
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Offline b.lindsey

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Re: Steam Chest Drill Wrong
« Reply #3 on: July 28, 2015, 11:23:23 PM »
Jerry, I agree with Stan, but do you know why the hole wandered in the first place?  Worn or poor drill geometry perhaps? If you don't find the root cause then plugging and redrilling will likely only repeat the same problem if you use the same set-up and drill bit. Just my $.02

Bill

Offline jmccrack

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Re: Steam Chest Drill Wrong
« Reply #4 on: July 29, 2015, 04:17:21 AM »
 Yeah I know what happened. I centered drilled the first hole, then drilled through with the 3/32 drill and when I hit the rough to casting on the other side the drill wondered and I didn't notice. I don't  have Center drills that long .  Best is to drill bigger, sleeve then re drill

Offline sbwhart

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Re: Steam Chest Drill Wrong
« Reply #5 on: July 29, 2015, 05:55:26 AM »
Yeah I know what happened. I centered drilled the first hole, then drilled through with the 3/32 drill and when I hit the rough to casting on the other side the drill wondered and I didn't notice. I don't  have Center drills that long .  Best is to drill bigger, sleeve then re drill

Plug the hole up and re-drill but this time use a long series centre drill to give the second hole a start in the correct position.

A little bit of clearance never got in the way

Offline Jo

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Re: Steam Chest Drill Wrong
« Reply #6 on: July 29, 2015, 08:16:32 AM »
Hi Jim,

When you need to drill a hole in a casting it is best to start by running a file over the surface smooth out  the cast surface which may have more hard bits in it and to make it flat.

If you try to plug the hole with something that is the same diameter as the hole when you drill the correct hole a short distance away there will not be much of the plug left and it is highly likely to fall out  :(

What is tight? I will guess the threaded part of the rod... This is normal when you cut the thread a little is pushed up making the diameter of the rod bigger. Just take these burrs of with a gentle lick with a needle file. The other thing could be that the drill has made the hole undersized: Do you have a reamer the right sized? It is always best to ream a hole like this rather than leave it as a drill cut surface if you can.



Having the valve rod slightly off line is not going to stop a 10V from running and the slight miss alignment will hardly be noticeable once the engine is together so I would leave it as it is  ;).

Making your first engine is all about experiencing these learning opportunities and even when you think you should be able to get it right they find new challenges to keep us on our toes  :).

Jo
« Last Edit: July 29, 2015, 08:20:34 AM by Jo »
Usus est optimum magister

Offline jmccrack

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Re: Steam Chest Drill Wrong
« Reply #7 on: July 29, 2015, 05:29:47 PM »
Jo
Thanks. The bottom hole is out of alignment right to left, not up and down. So I guess the valve will stay flat as it slides back and forth. An interesting way to re sleeve would be to cut the guide end off from the outside , drill a larger hole , sleeve it with brass and locktite it all in place. Interesting.

Cheers Jerry

Offline Alan Haisley

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Re: Steam Chest Drill Wrong
« Reply #8 on: July 29, 2015, 08:26:22 PM »
Jerry,
Your picture shows a parting line, which implies a bit of draft angle both above and below where you are trying to drill. Fill the hole, Then before going further, clamp it up in the mill and mill as much of that surface as you can reach so that you have a smooth surface at right angles to the drill axis. Now, punch it as Marv suggests and then watch the drill carefully. If it starts straight it should stay straight enough to give a good hole.
File and polish the rod as Jo suggests. Having it a bit undersized - or having the hole a bit oversized - shouldn't affect the valve function; after all, the valve is meant to float on the rod nut anyway.
Alan
Near Raleigh, NC, USA

Offline jmccrack

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Re: Steam Chest Drill Wrong
« Reply #9 on: July 29, 2015, 09:50:33 PM »
Thanks guys
As you can see in the attached pics it's done. Because I set up the part up right in the beginning when I used a slot drill to drill the hole it was I the right place. So when I sleeved it I drilled the hole in the sleeve before pressing it in place and everything lined up.

Offline b.lindsey

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Re: Steam Chest Drill Wrong
« Reply #10 on: July 29, 2015, 11:51:53 PM »
Hi Jim, glad you got it sorted out to your satisfaction. Let me ask one favor however, when posting pictures it is best for the sake of those with lower connection speeds and to save forum server space to reduce picture sizes to no more than 800 X 600 pixels. The forum software automatically reduces the picture size for display so one doesn't have to scroll around the screen to see the whole image, but it doesn't reduce the actual file size. There is no advantage in terms of clarity for the huge file sizes and most any of the free editing software will easily reduce the size of the file. Thanks in advance.

Bill

Offline kvom

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Re: Steam Chest Drill Wrong
« Reply #11 on: July 30, 2015, 12:26:15 AM »
Some alternate solutions to this issue:

1) Turn the end of the valve rod smaller so that it meets the off-center hole

2) Make the rod short enough to not need the slide hole at all.  On a small engine it's not that critical to have the end of the rod supported as it won't flex a great deal.

Offline krv3000

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Re: Steam Chest Drill Wrong
« Reply #12 on: August 01, 2015, 08:56:48 PM »
hi just a tip don't drill into a void all ways plug the hole i.e make a block to fit in to the valve chest you can glue it in place if its a bit slack with super glue and use methylated spirits as a activator to harden the super glue the drill will not wonder off to remove the block just heat it up and it will drop out