Tru Turn adapter size for To Jett 67LS?

[kevin king]

Hi All. I am looking to buy a couple of Tru Turn Aluminum spinners for my Ro Jett 67. Tru Turn's website says the adapters are not included, and the Ro Jett 67 is not listed in their menu. Does anyone know which adapters I will need? It's for the standard 2 1/4" spinner. One 2 blade, and one 3 blade spinner. I want to make sure I order the right adapters.

[John Lindberg]

Are you talking about the nut and washer that tightens down on the prop, or the ring that fits the prop shaft and then fits the hole drilled in the spinner backplate? I think most Tru-Turn backplates are drilled 3/8 of an inch, the thread size of the threaded prop shaft is the same as a OS, I believe it is 1/4x28 inch.

[Brett Buck]

Hi All. I am looking to buy a couple of Tru Turn Aluminum spinners for my Ro Jett 67. Tru Turn's website says the adapters are not included, and the Ro Jett 67 is not listed in their menu. Does anyone know which adapters I will need? It's for the standard 2 1/4" spinner. One 2 blade, and one 3 blade spinner. I want to make sure I order the right adapters.

  I assume it is like the 51/61. The prop stud is almost certainly 1/4-28, the spinner backplate registers on a 3/8" stub that is the end of the crankshaft. So you get the 1/4-28 adapter set, and don't use the backplate centering ring, because the backplate already has a 3/8" hole.

    Brett

[Avaiojet]

Hi All. I am looking to buy a couple of Tru Turn Aluminum spinners for my Ro Jett 67. Tru Turn's website says the adapters are not included, and the Ro Jett 67 is not listed in their menu. Does anyone know which adapters I will need? It's for the standard 2 1/4" spinner. One 2 blade, and one 3 blade spinner. I want to make sure I order the right adapters.

Kevin,

I have much of that stuff from Tru-Turn.

I should gather it and take a photo.

I'll see if I have a spinner.

Charles

[John Lindberg]

  I assume it is like the 51/61. The prop stud is almost certainly 1/4-28, the spinner backplate registers on a 3/8" stub that is the end of the crankshaft. So you get the 1/4-28 adapter set, and don't use the backplate centering ring, because the backplate already has a 3/8" hole.

    Brett

Yes, I forgot about the thrust washer adapter. Kevin, maybe call or email Dub Jett, he is extremely helpful.

[kevin king]

Thanks all. I appreciate it! PS, Also noticed I will need to open up the hole in the backplate  from 1/4" to 3/8" because there is a small step on the motor right after the threaded shaft, like Brett mentioned. (I only had a smaller 2" spinner with a 1/4" hole in the backplate) This actually threw me off. The spinner to airplane gap was so large I thought I was going to have to lengthen the nose and then repaint the nose! It couldn't happen to be in the worst place! Ink lines, camouflage, shark mouth and eye! Yikes!

[Brett Buck]

Thanks all. I appreciate it! PS, Also noticed I will need to open up the hole in the backplate  from 1/4" to 3/8" because there is a small step on the motor right after the threaded shaft! This actually threw me off. The spinner to airplane gap was so large I thought I was going to have to lengthen the nose and then repaint the nose! It couldn't happen to be in the worst place! Ink lines, camouflage, shark mouth and eye! Yikes!

      The Tru-Turn backplate should already have a 3/8" hole, it centers up on the stub of the crankshaft with no adapters.

     Brett

[kevin king]

Yes! Thanks Brett. The smaller 2" Tru Turn spinner I had only had a 1/4" hole in the back plate.

[kevin king]

Hi Charles, yes if you have a 2 1/4" "standard" shaped spinner I will buy it. It's kind of an obscure size. I am looking for a 2 and 3 blade spinner. I searched my stash and I already have the adapter I need from a 2" spinner.

[kevin king]

Thanks John. I did talk to Dub and he indeed has a lighter and less expensive adapter for the Ro Jett engines. Reason I am going to an aluminum spinner is because I need more nose weight so... Anyway I found an adapter that fits from an old 2" Tru Turn spinner.

[Brett Buck]

Yes! Thanks Brett. The smaller 2" Tru Turn spinner I had only had a 1/4" hole in the back plate.

    That is odd, all of mine are the same (1 3/4 and 2" "conventional" shape), with a 3/8 hole, and the intent is to use an adapter ring which comes with the nut, and is the same size,  to center it up.

    Brett

[kevin king]

Hi Brett, it is possible it's not a True turn spinner backplate so I am posting pictures of it. If it's another brand of backplate other than Tru Turn I apologize for the confusion. I bought it 20 years ago and I could be wrong about the brand.

[kevin king]

Here I was opening the hole in the backplate just enough to clear the step on the engines shaft, and that's when I realised I may not have to extend and repaint the nose!

[kevin king]

 Here I fit an actual 2 1/4 spinner on it.

[Avaiojet]

Kevin,

I don't understand?

The nose of your model is finished. What diameter spinner do you need?

It cannot be both? How can both fit?

Charles

[kevin king]

Hi Charles . I am looking for a 2 1/4" Tru Turn spinner. One 2 blade and one 3 blade.

[Avaiojet]

Hi Charles . I am looking for a 2 1/4" Tru Turn spinner. One 2 blade and one 3 blade.

Kevin,

OK, I'll see what I have.

You can drill the back plate to go past that, "thing" if you have to. 

Charles

[kevin king]

Haha. My thinking to not drill all the way through was to minimize the possibility of the hole being off center.  😁 PS, Where's the spinners you said you would look for?

[Avaiojet]

Haha. My thinking to not drill all the way through was to minimize the possibility of the hole being off center.  😁 PS, Where's the spinners you said you would look for?

Hey! I looked. I have your bloody spinner and it's only been a few hours.

You know you're going to have to paint the spinner red then clear coat. That means you have to scratch the spinner up. The spinner is 2.25" in diameter and 2.25" in height, two blade.

The whole in the back plate is 3/8". What is the diameter of that "thing?"

You'll need an adapter in front of the prop nut that fits the threads on the shaft. I said I have some. Do you know the shaft diameter and thread?

Charles

[kevin king]

  The diameter of the step is 3/8". The thread is 1/4" -28 same as OS.  Paint it red? I want to paint it white like the one in this photo. Nicest Spitfire on earth. Bar none.  😁

[Avaiojet]

  The diameter of the step is 3/8". The thread is 1/4" -28 same as OS.  Paint it red? I want to paint it white like the one in this photo. Nicest Spitfire on earth. Bar none.  😁

OK, OK, White. Most are red, I didn't see your image when I wrote that. You'll still have to paint it and clear it and it should be primed.

1/4" 28, are you sure? I said you will need an adapter for the spinner nut. You know this, correct?

I need a measurement. With the engine bolted in place measure from the face of the knurled engine thrust washer to the end of the shaft.

Get it right.

I'll see if I have an adapter that will work.

Charles

[kevin king]

Yes I'm sure it's 1/4-28 because both John and Brett confirmed it. And the distance from the knurled engine thrust washer to the end of the threaded shaft is 1 and 1/8" inches long with the engine installed.

[Avaiojet]

Yes I'm sure it's 1/4-28 because both John and Brett confirmed it. And the distance from the knurled engine thrust washer to the end of the threaded shaft is 1 and 1/8" inches long with the engine installed.

I'm really surprised that engine only has a .25" shaft.

Let me know what the threads are on a vintage McCoy .35 and a vintage FOX .35? I believe they are different?

This will help me to see what I have. No point in sending you stuff that won't work.

Charles

[Brett Buck]

OK, OK, White. Most are red, I didn't see your image when I wrote that. You'll still have to paint it and clear it and it should be primed.

1/4" 28, are you sure? I said you will need an adapter for the spinner nut. You know this, correct?

I need a measurement. With the engine bolted in place measure from the face of the knurled engine thrust washer to the end of the shaft.

   You do not need a measurement. If the prop stud is too long, you cut it off, or get a shorter one, if it is too short, you get a longer one.

    It uses a stock Tru-Turn 1/4-28 nut. The adapter ring is not used.  The backplate has a 3/8" hole that centers the backplate on the stub crankshaft with no adapters or spacers of any type.

Get it right.

You never cease to amaze.

     Brett

[Brett Buck]

I'm really surprised that engine only has a .25" shaft.

Let me know what the threads are on a vintage McCoy .35 and a vintage FOX .35? I believe they are different?

This will help me to see what I have. No point in sending you stuff that won't work.

Charles

    It *does not have a 1/4" shaft*. It has a 1/4" prop stud that is threaded into the front of the crankshaft. That is the same thread as a Fox and OS, and almost every other engine aside from a Nelson/PA (which is 5/16).  The end of the crankshaft is that stub you see sticking out, it has a 3/8" stub at the end, so it fits most common spinners, including the Tru-Turn, with no adapter rings. 3/8" is the largest common prop screw diameter, most manufacturer's spinners use 3/8 holes and provide adapter rings for smaller shafts. Those are not used with the Jett.

    The stud is used because if you crash, in almost all cases, the stud might bend, but the crankshaft will not, so all you do is unscrew the bent stud and replace it, cost about 25 cents in bulk. This has been extensively tested in repeated 200 mile/hour crashes into pavement.

      Brett

[Avaiojet]

    It *does not have a 1/4" shaft*. It has a 1/4" prop stud that is threaded into the front of the crankshaft. That is the same as a Fox and OS, and almost every other engine aside from a Nelson/PA (which is 5/16).  The end of the crankshaft is that stub you see sticking out, it has a 3/8" stub at the end, so it fits most common spinners, including the Tru-Turn, with no adapter rings. 3/8" is the largest common prop screw diameter, most manufacturer's spinners use 3/8 holes and provide adapter rings for smaller shafts. Those are not used with the Jett.

    The stud is used because if you crash, in almost all cases, the stud might bend, but the crankshaft will not, so all you do is unscrew the bent stud and replace it, cost about 25 cents in bulk. This has been extensively tested in repeated 200 mile/hour crashes into pavement.

      Brett

Clever engineering.

So the vintage FOX .35 is 1/4"-28.

The vintage McCoy .35 I don't believe is?

Charles

[Dan McEntee]

Clever engineering.

So the vintage FOX .35 is 1/4"-28.

The vintage McCoy .35 I don't believe is?

Charles

   Yes, the McCoy .35 has 1/4"-28 threaded shaft. The list of engines that DOES NOT have a 1/4" threaded shaft is a lot shorter than those that do. For someone that claims to be a life long modeler with all your experience since the 1950's, I'm really surprised that you don't know that.
    Now, for extra points, and a chance to redeem yourself, what exactly does "1/4-28" mean?? And no using google!!!
     And for double bonus points,, what is the next size down that is typical for most small bore model engines??
    Type at you later,
    Dan McEntee

[Brett Buck]

Clever engineering.

So the vintage FOX .35 is 1/4"-28.

The vintage McCoy .35 I don't believe is?

   A McCoy 35 is 1/4-28 also. It's nearly universal, even OS and ST use 1/4-28 despite everything else being metric. The ST has a 7mm shoulder that causes the same sort of problem Kevin found with the Jett, but the thread is 1/4-28. There are smaller threads on small engines, and the most notable stunt engine that deviates being the PA, which uses a 5/16-24.

     The prop stud arrangement used for the Jett and RO-Jett *is* unusual, but not unique.

     Brett

     

[Avaiojet]

   A McCoy 35 is 1/4-28 also. It's nearly universal, even OS and ST use 1/4-28 despite everything else being metric. The ST has a 7mm shoulder that causes the same sort of problem Kevin found with the Jett, but the thread is 1/4-28. There are smaller threads on small engines, and the most notable stunt engine that deviates being the PA, which uses a 5/16-24.

     The prop stud arrangement used for the Jett and RO-Jett *is* unusual, but not unique.

     Brett

Thanks Brett,

I just wanted to be sure. Kevin is a great guy and works hard at his modeling detail.

This is Kevin's Thread and not mine, Kevin I'm sorry it's getting muddy.

BTW. Kevin is in Canada. I wouldn't want him to have stuff that doesn't fit, even for the savings in money. It must fit.

Brett, thanks again for the detailed reply. It's appreciated.

Charles

[Brett Buck]

Here I was opening the hole in the backplate just enough to clear the step on the engines shaft, and that's when I realised I may not have to extend and repaint the nose!

   It looks like a Tru-Turn from the front, but none of my Tru-Turn backplates have a raised boss on the back - they are flat across. This looks like a copy. It looks like you have plenty of clearance for a flat backplate, from your earlier pictures.

   Most quality spinners have flat backplates, for precisely the reason you had a problem - so they all fit the same way.

     Brett

   Tru-Turn front. Hole is 3/8" without centering ring:



   Rear:

[Brett Buck]

Continuing, the stub crankshaft and prop stud:

[Brett Buck]

Prop stud hex cap, and tightening with 1/8" Allen wrench. The stud is just a long hex-key set screw. Naturally, oil it before assembly.

[Brett Buck]

Backplate pushed up to thrust washer. 3/8 backplate hole registers and centers up on 3/8 stub crankshaft.