Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 29127 times)

Online crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #270 on: March 31, 2019, 07:09:37 PM »
If you have another small chunk of the same steel, you could always cut off the end and silver solder a new end on it. I did that on my Shay frames after a measure-once-cut-twice boo-boo.

Offline fumopuc

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #271 on: March 31, 2019, 08:16:23 PM »
Hi Kim, I feel your pain, but as already said, remake seems to be the best option.
And spend some more money for industrial quality tabs.
My two Cent after banning the Chinese stuff from my shop.
What may be the reason for that ban ?
Kind Regards
Achim

Offline Dave Otto

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #272 on: March 31, 2019, 08:43:01 PM »


Dave, actually my mill does have a Ram head, and that a great idea!  I've got to learn how to use the capabilities of my new tools. I have to learn to think differently...


Thank you all for helping me to think of options.  I really appreciate it.
Kim

I was looking for a picture, but me and the forum search tool don't always get along.  :lolb:

Dave

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #273 on: March 31, 2019, 10:40:05 PM »
Kim, I just went back through your pictures in the posts above. The tap in the pics does not appear to have flutes, or maybe just one flute. Are you using thread forming taps in steel, rather than the more usual spiral pointed "gun" taps or "plug" taps? If you are using fluteless or thread forming taps in steel, I would expect you may have lots of breakages.

The gun taps will cut better and faster than any other kind I have used, especially in thru-holes. If using them in blind holes they have to be backed out and cleared of chips every few turns.

Just to give you an idea of the ones I mean you can see them at the following McMaster Carr link. I do prefer Butterfield or FEW brand HSS taps though, for quality of thread and staying sharp the longest.

https://www.mcmaster.com/spiral-point-taps

If you already know about all this, or if I'm not seeing the taps correctly in your pics, please excuse me for stating the obvious - just disregard it. Standing by with  :popcorn: :popcorn: :popcorn: for your next progress post.

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #274 on: March 31, 2019, 11:01:08 PM »
If you have another small chunk of the same steel, you could always cut off the end and silver solder a new end on it. I did that on my Shay frames after a measure-once-cut-twice boo-boo.
Considering this.  though as has been said, likely more trouble than its worth, but I might give it a shot anyway.  Maybe I'll go to double the work to NOT have to re-do work :)  But not 4x.  And Definitely not 10x. I have my limits!  :Lol:

Hi Kim, I feel your pain, but as already said, remake seems to be the best option.
And spend some more money for industrial quality tabs.
My two Cent after banning the Chinese stuff from my shop.
What may be the reason for that ban ?
Thanks Achim,  yeah, might go the remake route.  But I'm going to struggle with it for a bit before I go that way. Even though its likely the best option  ;)

I was looking for a picture, but me and the forum search tool don't always get along.  :lolb:
Yes, I've found the same.  The search engine built into the forum software is marginal at best.  I tend to have better luck just doing a google search and including "ModelEnginenMaker" in the search.  I often get better forum results that way!
Kim


Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #275 on: March 31, 2019, 11:15:15 PM »
Hi Cnr,
Yes, you're seeing right. I'm using forming taps. And I've used them in steel before and they have mostly worked - I try to stay under 75% threads. These should have been about 60%. But maybe that is part of the problem.  They work well in the 12L14.  I've used them in 1018 quite a bit and haven't had any significant problems that I can recall (and I tend to recall this kind of problem). But clearly I can't say that any more!  So maybe I'm asking too much from them?

You're thinking I should go to a spiral tap for the 1018 steel?  I'm OK with getting more tools :)  May have to consider this.

If you already know about all this, or if I'm not seeing the taps correctly in your pics, please excuse me for stating the obvious - just disregard it.
Cnr, please never worry about that in any reply to me.  Even if I know it, it won't hurt to hear it again. And if people hold back giving me good advise, I'm the worse for it!  Besides, even if I knew it, I wasn't taking advantage of my knowledge because I clearly broke the tap! This is exactly why I share my foibles (and there are plenty of them!);  so I can learn and get incrementally better with every screw-up. ( I mean, I already messed up, so I might as well get something worthwhile out of it, right?  :Lol: )

Looks like I might be asking too much out of the form taps?  They've done so well for me in the past, even in steel.  But if they are going to be questionable, maybe I should invest in some spiral cutting taps or something else?  Am I asking too much from a form tap when it comes to 1018?  what about stainless (303)?

Thanks,
Kim

Offline Dave Otto

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #276 on: April 01, 2019, 12:09:44 AM »
Hi Kim

You should be able roll form tap any ductile material including SS. Personally for hand tapping I would rather use a cutting tap, and that is not saying hand tapping with a form tap is wrong; just my preference. I wouldn't hesitate to run a form tap under power in a machine or with a tapping head, but hand tap, probably not.
I think the form tap will be less forgiving to any misalignment. Another thing to consider as this is a forming operation and not a cutting one, the choice of lube may be different than with a cut tap. I would have to do some poking around to see what might be better.    Moly-Dee maybe?

Dave

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #277 on: April 01, 2019, 12:26:29 AM »
Thanks Dave, appreciate the input.

I've been using my general purpose lube for the forming tap too - Magic Tap.  It has worked pretty well for most things, but I clearly don't know what would be best. It's just what I've got handy.

My reasoning for the form taps is that since they don't have any flutes, they have a larger cross-section and therefore should be stronger.  Again, this was my thinking (though I do think I read that somewhere, it still doesn't mean its correct).  Plus, I've had much better luck with the form taps than with cutting taps.

Or, at least I think I have.  It's hard to say though. I broke more taps early in my model machining career than I have lately. But that may or may not be only the tap. Hopefully, I'm getting better at my setups and keeping things carefully aligned during tapping. That might skew things to looking better regardless.  Over the last several years I've switched almost exclusively to form taps. I've been attributing my better luck with tapping to this.  But there are so many variables.  The form taps I've purchased are much higher quality than the cheap Chinese cutting taps I used initially. That, and the experience thing make me wonder if my faith in form taps might be misplaced. Help! I'm having an existential tap crisis!  :help:  :Jester:

I think I'll be looking at getting some quality cutting taps and seeing how those serve me...
Kim

Kim

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #278 on: April 01, 2019, 12:29:34 AM »
OK, my current-most-likely-plan-of-attack is to cut a 5/16Ēx 3/4" chunk from the corner of the side sill and silver solder a little piece of steel back in its place.

My first step would be to use a slitting saw to cut underneath the broken tap and then use an end mill to remove the chunk from the main part.  This way I donít have to mill through the tap.



Then Iíll clean up the notch, cut an appropriately sized piece of steel, and solder in place.

I wonít get around to this till next weekend at the earliest, so Iím still not committed.  Please feel free to comment if you have any thoughts/recommendations.

Thanks,
Kim


Offline kvom

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #279 on: April 01, 2019, 12:33:07 AM »
Powder coating will be fine for everything except for possibly the stack.  Curing temp is typically 400F.  I've been using it on my latest project and don't expect to paint any models henceforth.

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #280 on: April 01, 2019, 01:04:01 AM »
Thanks Kvom,
I've been looking into powder coating and think I know what I'll be asking for for my Birthday!  :)  Seems like a great idea!  Always game to try something new!
Kim

Offline Florian Eberhard

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #281 on: April 01, 2019, 05:41:59 PM »
Hey Kim

Why not using the hacksaw to cut that out and clean up with an endmill? IMHO, this should be the fastest way. (at least if your hacksaw blade is sharp)

Florian

Offline kvom

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #282 on: April 01, 2019, 07:52:31 PM »
Is the tapped hole really that deep?

You could try drilling it out using a carbide endmill.

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #283 on: April 01, 2019, 10:08:06 PM »
That's a good idea Florian!  Hack saw shouldn't be too hard :)

Kvom, well, its not 3/4" deep, but the tap is at least 3/8" deep, maybe a smidge more.
Kim

Offline Tennessee Whiskey

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #284 on: April 01, 2019, 10:47:33 PM »
Commisioneratios on the tap. Youíre on the right track: nip that corner out nice and square, silver solder in an oversized piece, and mill to dimension. Painting or powder coating will hide all sins. Nobody but us will know in the end. Just a Cletus POV  :lolb:

Cletus