Chapman GP7 Project

Re: GP7 Project - Mitsumi M15N-3 motors

Postby ConnRiver » Sun Nov 06, 2016 1:27 pm

So, yesterday, this little box arrives in the mail. Hmmm, must be the Mitsumi motors, I think, but I ordered 10 motors. My order must have been shorted. But, no, all 10 tiny little critters were inside. I reminded myself just how new I am to TT scale; it's easy to forget how small -- even though items loom larger than N scale -- it is.

Mitsumis - 2.jpg

To fit flywheels on both ends, the stub axle will have to be lengthened: Don't know if the axle itself can be readjusted or whether the motors will have to be custom ordered to suit. IIRC, seems I read the latter was possible on the aliexpress site?

In the photo, I positioned one motor atop the plastic frame of a Lionel TT scale GP7 (thanks, Al!) Also, I slipped a motor around inside the metal body shell of the Lionel, and it fit . . . barely. Only a few thousands clearance. The digital micrometer revealed the Lionel GP7 has an interior width of 0.490". The plastic resin shell should have an interior width of 0.500"-0.520" so all is good that way.

My next issue: Worms. I probably should have begun the truck tower design by first selecting an available worm and worked from there, attempting to discover what size spur gears would accommodate both the worm and the truck casing.

Anyone know of a worm calculator? I haven't looked yet; maybe someone can point to one before I begin looking. And, I can review the Boston Gear worm literature, too.

Please post comments and ideas you might have.
Brian Chapman
Cedar Rapids, Iowa / USA
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Re: Chapman GP7 Project

Postby krokodil » Sun Nov 06, 2016 1:53 pm

Nice motors!

Probably you have to change the design and use just a single flywheel ( easier as to adjust the motor axle) the effect of tne flywheel depends only on the diameter and the weigth.

What do you want to calculate on the worms? There is usually nothing to calculate, the diameter can be any.
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Re: Chapman GP7 Project

Postby ConnRiver » Sun Nov 06, 2016 2:34 pm

krokodil wrote:Nice motors!

Probably you have to change the design and use just a single flywheel ( easier as to adjust the motor axle) the effect of tne flywheel depends only on the diameter and the weigth.

What do you want to calculate on the worms? There is usually nothing to calculate, the diameter can be any.


Would one flywheel perform as well as two? That is, the difference would be so minimal as to be unnoticeable?

The worm has to fit the diametral pitch of the spur gear? (I need to review gears again, it's been awhile. . . .)
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Re: Chapman GP7 Project

Postby krokodil » Sun Nov 06, 2016 2:48 pm

As I told you, the effect of the flywheel depends on the diameter and the weigth only. You can have one bigger flywheel on one motor end to have the effect of two smaller flywheels.

On the worm only the thread should match the pitch of the spur gears. Either you get them ready made or in the shop they will make you a suitable thread on brass rod.
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Re: Chapman GP7 Project

Postby MacG » Sun Nov 06, 2016 7:03 pm

An another option is, that the flywheel holds the drive shaft or it is narrower at the axle as at the outer diameter.
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Re: Chapman GP7 Project

Postby areibel » Sun Nov 06, 2016 7:38 pm

I think MacG has a good idea- If you can mount the flywheel to the motor then mount the cup for the dogbone on the other end that would solve the short shaft problem. Even if you have to use a short piece of shaft stock to mount the cup you could keep it close to the flywheel and leave the distance for the dog bone longer so binding wouldn't be an issue.
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Re: Chapman GP7 Project

Postby krokodil » Mon Nov 07, 2016 1:07 am

The flywheel is a precison item usually not a commercially available product. Please consult with a toolmaker specialist, he will have several ideas how to make it easier (cheaper) and also for a secure installation (press fit on the axle). It is a quite complex task as the installed flywheel cannot be usually removed, ie you can throw away the whole motor with the badly pressed flywheel.
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Re: Chapman GP7 Project

Postby sd80mac » Mon Nov 07, 2016 5:20 am

I personally believe that you have more than enough shaft length (4-5mm) to mount a flywheel on the short end. The shaft is about 6mm long and a 10-12mm diameter flywheel at least 10-12mm in length would fit fine. For drive shafts, I still recommend the "hex" style, with a 4mm hex socket machined in one end of the flywheel, aka Athearn RTR/Genesis and Kato.

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Re: Chapman GP7 Project

Postby ConnRiver » Wed Nov 09, 2016 7:58 pm

This is, in all likelihood, my goodbye post to all of you wonderful people here at TT_Nut.

The election of a man who is likely to become, in my mind and informed by my personal instincts, an American Putin (Arseny, please forgive me, in no way do I wish to be insulting to you) leaves me scrambling. I had hoped -- I had intended -- to create a tiny manufacturing house that could in some way help advance TT scale. I had dreams . . . and, yes, I thought I had a head of steam heading down the track toward creating real products.

Truly, I believe the clown who will soon inhabit a White House designed by Washington, and occupied by Lincoln in the severest of times for our republic, will create a series of constitutional crises that will imperil the republic and result in horrific economic chaos. I can't risk pursuing my high risk TT dreams when measured against the economic devastation that looms on the horizon. I must work elsewhere in some venue that gives my family a chance for economic survival.

I do not state these fears without at least a minimal background in things political and things American history; both were my majors of study in college. And since those days, I have been a voracious reader in those subjects. I fear for our future.

My friends, I wish you all the very best. So long.

-Brian Chapman
Cedar Rapids, Iowa

(Can you imagine a confrontation between Russian Putin and American Putin in which each claims to have the biggest balls? How will that end? I shudder to think. My god, in some ways this feels like January 1933.)
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Re: Chapman GP7 Project

Postby ConducTTor » Wed Nov 09, 2016 9:28 pm

:cry: :cry: :cry: :cry: :cry: :cry:
What people think: "liberals/conservatives are ruining my country"
What the powerful know: divide and conquer
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