Author Topic: Steam Tractor 3/4" (Rudy K)  (Read 242074 times)

Offline Jo

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #660 on: May 14, 2017, 08:22:27 AM »
:thinking: What were you using to lubricate the die Kim? and how were you winding the die on? 

I am very fond of using my Whirlwind dies on 303 for thread cutting as them and the Coventry die heads seem to be happiest cutting it. I also find the TQS dies are good on 303. Other modern HSS dies have to be of a very good parentage of they have a habit of breaking off the work...

Thread cutting something that small   :o It can be done  :paranoia:

Jo
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Offline 90LX_Notch

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #661 on: May 14, 2017, 11:01:24 AM »
Kim-

You can single point it.  Everything about the tool has to be perfect: dead sharp, honed,  on center, properly aligned and lots of spring cuts.    For that size I just grind the tool as a Sharp V Thread.  I did write up over on HMEM years ago after I single point cut an 0-80 thread.

http://www.homemodelenginemachinist.com/showthread.php?s=82facf33b73d8f6f27c13cab0bff4fda&t=13848.

 The YouTube video linked in that thread is just a demo cut for that topic.



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Offline fumopuc

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #662 on: May 14, 2017, 01:28:39 PM »
Howdy everyone,
......
A couple hours into my session and it became clear to me that I needed to do something else. 

I see a new 2-56 die in my future.  And maybe some 3/32” stainless :)

Next time, maybe I’ll make some actual progress!
Kim
Hi Kim,
you have mentioned already the two possible reasons for the disapppointing day in the shop.
SS can have many different properties. What we need is an easy machining quality. I do not know the AISI grade, here in Germany I would prefer 1.4305 which should be similar to the 303.
I have made a lot of M2 threading in the past, also in SS. I have learned there very quick, that a die can have very different capability to cut a thread, especially in SS.
So all my far east dies has been replaced in the meantime  by industrial quality dies, I do not know any source in the US, but I highly recommemt to invest hear some money.
The price for a M2 die at a German industrial tool dealer is about EUR 25,   in the UK it should be similar.
I know it may be sounds hard, but on the other side, may be in the near future, it will save you the one and only shop day in that week.
Kind Regards
Achim

Offline Kim

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #663 on: May 15, 2017, 05:59:39 AM »
Thanks Bill, Jo, Bob, and Achim, for the friendly advice!  It is always appreciated!

The SS is 303, so I should be good on that front.  I was using tap magic, and was doing my standard wind or two, then backup a bit.  However, I think I was a little too aggressive (clearly!) and wasn't breaking the chips enough.

I have no previous experience threading Stainless.  I've threaded 1018, 12L14, aluminum and brass, but have never used a die on 303.  So it's all part of the magical learning process.  I clearly need to be more careful with the 303.

I'm sure my die is your standard run-in-the-mill Chinese die.  I tried looking for a better one,
 but I couldn't find anything but Union Butterfield on Amazon, and they wanted just at $100 for one die. And while I'm sure its very good quality, that was a bit rich for my blood.

I have since found OSG on MSC for about $35 for a die.  Is it really worth 7x for the OSG die? Are they a good brand?  If someone has experience there, I'd go ahead and order one of those. I know the quality drills I purchased about a year ago have made a huge difference. I was a skeptic there too, but they are truly a pleasure to use!  If an OSG die (or some other brand you can recommend) would be a good investment, I'm willing to give it a shot.

Thanks,
Kim

Offline wirralcnc

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #664 on: May 15, 2017, 06:15:09 AM »
Kim
Looking at yours pictures of your split die and holder, maybe you have over tightened the die in the holder.
The grub screws should really fit in the  split of the  die and can be used to adjust the thread your cutting.
Maybe crushing the die to a smaller cutting diameter, therfore ripping the thread and causing you to put excessive force into cutting.

You can adjust die and take a 2nd cut to get a good fitting thread.

Robbie

Offline Kim

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #665 on: May 15, 2017, 06:38:13 AM »
Thank you Robbie,
Yet another good idea on what went wrong.  I will be sure the die is open appropriately next time too.  One more vector to look into.

Yet another thing I read about is work hardening in stainless.  Is that an issue with 303?  And if so, what can be done to help address it?

Thanks,
Kim

Offline fumopuc

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #666 on: May 15, 2017, 10:19:03 AM »
... a good source, but unfortunately far away from your home.
http://www.gewindebohrer.de/shop/catalog/product_info.php/info/p766_BAER-cutting-die-UNC-NR--2-x-56---HSS.html
This is the section, specially for SS, but not all sizes are available in Germany, the prices are really high.
http://www.gewindebohrer.de/shop/catalog/index.php/cat/c272_for-stainless-steels.html
I have never used one of this super special stainless cutter until now.
Another good source in Europe, may be the brand names will help to find it in the US.
https://www.gewindebohrer-shop.de/unc-schneideisen-gewindeschneider-c-129.html
http://shop.klein-mess.de/cgi-bin/shop/front/eidamo.cgi?func=anzeige&wkid=1586129493450964&rub1=063%20%2D%20Schneideisen%20UNC%20amerik%2E%20Grobgewinde


Kind Regards
Achim

Offline Walsheng

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #667 on: May 15, 2017, 12:52:14 PM »
Thank you Robbie,
Yet another good idea on what went wrong.  I will be sure the die is open appropriately next time too.  One more vector to look into.

Yet another thing I read about is work hardening in stainless.  Is that an issue with 303?  And if so, what can be done to help address it?

Thanks,
Kim

Kim,  I machine a lot of 303 stainless in making molds for silicone medical part molds and have not found it to work harden.  When turning it I use a micro-drop oiler (compressed air that mixes in fine drops of oil.)  When milling I use coolant or RapidTap depending on if it is CNC or manual.

Love the build by the way and have followed from the start.

John

Offline Kim

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #668 on: May 15, 2017, 06:43:12 PM »
Thanks for the links Achim, appreciate it!

John, thanks for relating your experience here.  I've only used 303 a very little and thought it was nice to work with. But I've never tried threading it!  So its good to hear your experience on it.  Just getting a sharp die, making sure I don't have it clamped down too tight, and taking it easy, with plenty of cutting oil - I'm hoping that will get me there!

Thanks for all the input!
Kim

Offline 90LX_Notch

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #669 on: May 15, 2017, 07:12:31 PM »
Four simple words Kim:

No guts, no glory.  (Single point)

-Bob

Ps, 
OSG is very good.
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Offline b.lindsey

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #670 on: May 15, 2017, 09:01:04 PM »
Kim, OSG is a good brand. Check the MSC sales flyers and sometimes you will luck up and what you need on sale.

Bill

Offline Kim

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #671 on: May 20, 2017, 10:48:08 PM »
Well, with all my whining about threading stainless steel I did last week, this week turned out rather anticlimactic. Things just worked. :)

I got a new 2-56 die (a relatively inexpensive one, so Chinese made I’m sure), and some actual 3/32” stainless rod in the mail this week.  I turned a short bit of it down to the 2-56 size and just threaded it.  Nothing special.  I mean, I was careful, but it wasn’t anything big.  It just worked.


Here, I cut the section that locks into the valve.


And here it is, in place, just like that! :)


Next was the piston.  This was made from some 1/2" bronze rod.  I turned it down a little bit (the 1/2" stock was amost 3/32” oversized!), but not to the final size.  Then drilled & tapped 4-40.


After that, I cut it off the parent stock.  I used this little parting tool to go about half way through, then cut the rest of the way with a hacksaw.


Then I threaded the piston onto the piston rod I made (sorry no pictures, though it was quite boring – a length of 1/8” SS threaded 4-40 at both ends) and put that in the 1/8” collet.  With that, I turned the piston down to size, truing it up to the piston rod.  After that, I cut a notch for an o-ring:


Here’s the completed Piston, with Piston rod.


You can see I tested an O-ring with it and it worked fine, but I couldn’t get the O-ring back out, and I didn’t want to damage it (yet).  I’m not sure if I’m going to use the Viton O-ring or use some graphite string.  I’m kinda leaning toward the graphite string.  Any thoughts from anyone here?

Also, should I solder the piston on the rod?  Seems like trusting the 4-40 threads seems a little naïve.

Thanks for helping me along!
Kim
« Last Edit: July 08, 2017, 07:14:24 PM by Kim »

Offline steam guy willy

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #672 on: May 20, 2017, 11:43:37 PM »
Hi Kim , is the 2-56 thread  2mm X 56 threads per inch ?? i only use BA threads over her in blighty so am not familiar with this thread system ??   good work going here as well
Willbert.

Offline 90LX_Notch

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #673 on: May 20, 2017, 11:49:52 PM »
Nicely done Kim.

-Bob
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Offline b.lindsey

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Re: Steam Tractor 3/4" (Rudy K)
« Reply #674 on: May 21, 2017, 12:11:17 AM »
Kim, I could be that the teeth on the new dies were just sharp compared to the one last week. Either way  the threads and the piston assembly look great!!

Bill

 

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