Author Topic: PMR 7 Twin Cylinder Steam Engine  (Read 32069 times)

Offline Gas_mantle

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #90 on: April 17, 2018, 09:19:37 PM »
Carl I'm not sure what the blue Loctite is but in the UK the green stuff (638) is what I use to hold wheels for turning. If the parts are clean and free of oil it should hold ok for what you are aiming to do.

I've used it on a few wheels up to about 5" dia and never had one work loose in the lathe.

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #91 on: April 17, 2018, 09:38:46 PM »
Thanks Gas_mantle. And you've reminded me I have a bottle of 638 on the way.
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Offline Gas_mantle

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #92 on: April 17, 2018, 09:48:51 PM »
Thanks Gas_mantle. And you've reminded me I have a bottle of 638 on the way.

You'll be fine with that stuff, it is incredibly strong and starts to cure within seconds in the absence of air so I'd make sure you are totally happy with how the parts fit together before applying it.

Although it cures very fast I usually leave it a few hours to achieve good strength before machining.  I try to make sure the parts don't get very hot during machining, they probably wouldn't get hot enough to break the bond but it's worth keeping an eye on the situation  :)

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #93 on: April 17, 2018, 11:15:53 PM »
More nuts.

These are the packing nuts. I'm fairly happy with them but I need to get better at putting the angle on the hex.

It's amazing...when I first looked at the parts list and drawings...it seemed 'simple' in the sense of how much there is.
Whew...there's a lot of parts here and this is a simple model compared to the stuff we see on this forum.
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Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #94 on: April 17, 2018, 11:36:45 PM »
Question: I have a die holder that slips on a rod. The other end of the rod has an MT2 taper that fits the tail stock. Normally, if the MT2 taper end gets tightened into the tail stock, I simply back away the (watchamacallit thingie that is holding the taper - a quill?) and the taper pops out.

But not in this case. It be stuck even when backed all the way. Whatever is in the tail stock that pushes out the taper...isn't long enough for this tool.
I have no problem with the chuck (which has a tang for some reason.)

The way I've gotten it unstuck is to put the rod end in the head stock chuck and give it a twist. That's problematic in that there may be a part in the head stock that I don't want to remove.

I suppose I could take a pair of pliers (and a rag) and twist it off but I'm not sure I like the idea.

Are there alternatives?
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Offline Brian Rupnow

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #95 on: April 17, 2018, 11:48:41 PM »
Zee--I seen a similar thread about this somewhere last week. You can build up the end of the taper by mig welding (that's what I did), or--if the end is threaded you can screw a tang into it. I seen where someone got around the problem by glueing a magnet to the end of the taper.

Offline crueby

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #96 on: April 18, 2018, 12:09:05 AM »
Drill the narrow end of the taper,  tap, put a screw in to lengthen it. That will give the ejector thingy something to hit.  Some brands use the same taper angle but not the same length of the taper, Sherline for example uses a shorter portion.

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #97 on: April 18, 2018, 12:36:24 AM »
Thanks!

@Brian - welding is something I have no experience in (and at this point...no real interest...and some people I know will gasp at that). No threads.
@Chris - that should work. The rod is aluminum and will be easy to do.

Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline b.lindsey

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #98 on: April 18, 2018, 12:56:29 AM »
Just look at all the things you are learning on this build Zee. Both about machining and about your new tools. Still following along and think you are doing great.

Bill

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #99 on: April 18, 2018, 01:32:26 AM »
Just look at all the things you are learning on this build Zee. Both about machining and about your new tools. Still following along and think you are doing great.

Thanks Bill. I'm really enjoying the tools as I learn more about them. It was a good purchase.
Yes...I'm learning a lot. Including how stupid/silly/newbie I can be.
I try not to let it bother me. I've never met anyone who didn't pull a dumb one now and then.

Speaking of which...going back to Chris's suggestion for my taper stuck issue. I was setting up the chuck in the tail stock and lo and behold...it has a screw at the end of it just as Chris had suggested I do for my die holder rod.  :facepalm2: I felt foolish for having asked the question. Had I simply done a little comparison of tools...it would have occurred to me. I take solace in the hope that others find these posts useful.

Update on the flywheel. So far so good. I put the assembly (flywheel with loctite rod) in the lathe and had a go at facing the rim. That went well. Had quite a bit of chatter so I spent some time fiddling with speed and feed. I was taking very light cuts in hopes the flywheel wouldn't break free.

Now to figure out how to do the outer rim.

If all goes well tomorrow...pics.
If all goes badly tomorrow...pics.

Pics of something anyway.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Zee-Another Thread Trasher.

Offline b.lindsey

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #100 on: April 18, 2018, 01:38:13 AM »
Even with light cuts the rod alone likely isn't giving enough rigidity, hence the chatter.  If you are lucky you can find a speed/feed that will minimize or reduce it. The sharper the tool the better also. Just my two cents.

Bill

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #101 on: April 18, 2018, 01:48:55 AM »
Two updates:

1) I'm using an index cutter and the rod is held by a live center.

2) I couldn't wait so I started setting up to do the outer rim. The flywheel broke free just as the cutter engaged. Had no problem facing the side of the flywheel.
Sort of reminds me of trying to open a jar. Try as one might, it won't open, then hand it to someone else and poof, like it wasn't even tight.

I had forgotten I had dropped the speed significantly. Perhaps that was a factor?
In any case...it's a try again. Later.

Pic today. You all may have to pound sand for pics tomorrow.  ;D
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline crueby

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #102 on: April 18, 2018, 01:58:16 AM »
The speed could effect chatter, as can cutter hieght. For an indexed cutter, I have had the little screw that holds it to the shaft loosen up, letting the tip move, causing chatter. Check that too.


As for the taper, very clever of you to go back and n time, add the screw, then forget you did it!   :lolb:


Glad to see you diving in, best way to learn, all of us go through the same process. Doubt it ever ends!


 :cheers:

Offline b.lindsey

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #103 on: April 18, 2018, 02:01:53 AM »
The interrupted cut on the rim probably contributed to the breakaway of the Loctite joint. I would try a good sharp HSS toolbit and see if that helps Zee.  And if you haven't checked this outfit out, I recommend them for final finishing and polishing. Don put me on to them and I keep them on hand now, not just the set of four, but also the 1500 grit ones which can be bought separately and work well for finishing operations.

http://micro-surface.com/index.php/products-by-type/dual-angle-detailing-files/dual-angle-micro-mesh-regular-files.html

Bill

Offline zeeprogrammer

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Re: PMR 7 Twin Cylinder Steam Engine
« Reply #104 on: April 18, 2018, 02:19:30 AM »
Chris...Screw was tight. Cutter height was 'on center'. It was the same tool I use facing bar and had virtually no pip. So I don't think the cutter holder's adjustment screws had changed. (Having said that, when I went to turn the outer rim, I switched to a different index bit. I have little knowledge about the differences between index material, properties, etc. But I'd always felt good using this type and thought I'd try it. Except I couldn't.  ;D )

I wonder too that the rod is too long and could be springing. It's stainless steel. I would've used drill rod but didn't have any.

Bill...Thanks for the link. I've been looking for things like this.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

 

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