Well I mounted my Fox 35 on my sterling Yak 9, and I want to put a spinner on it 2.250" I tried a Dubro but I didn't have enough threads for the nut with the back plate and prop. So what spinner works????

Now that is a good question. [X(] I haven't uses any spinner like that in years. Unless it is absolute scale I only use spinner-nuts for models. Much easier and no hassles.
For scale spinners I usually go for metal. Try Dave brown Products, www.dbproducts.com or Tru-Turn for the high rent district. www.tru-turn.com
Maybe find something at Tower, www.towerhobbies.com

While I am in agreement with Hoss and use a lot of spinner nuts for not just Controlline but RC as well. With a short shaft situation the plastic Dubro is a very poor choice with an exremely thick backplate.

Tru turn has some thin backplate types but of course are all aluminum. If you really want a plastic then the Great Planes series with an aluminum back plate and a plastic cone are much thinner.

Other options may include opting for a larger diameter but finer pitched propellor.

John

Problem solved. I machined a thinner prop washer, and I have a very low profile lock nut. All the Hardware is the same as what is used on a Gulfstrem Biz Jet. Works perfect! I don't use many plastic spinners, for the most part I use prop nuts.

OK, I live vicariously... so where are the pictures?

Keep 'em light and tight...

No quite done, will post pics in the Got'em Post'em section.

There is an alternative...

Pretty sure Fox still offers spinner extension spools, nuts and washers. These are threaded 1/4-28 internally, or for larger engines, are 5/16-24 inside..

Other details: Aluminum nut shanks are 3/8" OD with the nut end to fit 1/2" sockets, steel nut shanks are 5/16" OD for 1/4-28 shafts, and the nut end fits the usual 7/16" socket. The spools - aluminum spacers - come in 1/2" and 3/4" length, as I recall. Unless you want to move the whole prop forward, even the 1/2" length is likely more than you need...

It's better not to use a shaft extension on a Fox 35 if you can possibly avoid it. ... Light engine structure; short, plain shaft bearing, and severe gyroscopic loads in flying sport/stunt CL ... Durability over time suffers. Shaft bearing wear can increase, if props aren't very carefully balanced.

If you have the machinery, it might be simple to cut an extension nut out of 1/2" hex aluminum extrusion. Thread internally to 1/4-28; turn 'extension/shank' length to 3/8" OD, long enough to enter a drilled-out prop, but not bottom on the thrust washer; add a 3/8"ID front washer, and leave the front 1/4"-5/16" length as 1/2" (across flats) hex. That fits the largest socket on usual 4-way prop/plug wrenches.

In steel or iron, there's enough strength in the wall thickness from the 1/4-28 thread to the 5/16" OD. In aluminum, Fox used 3/8" OD.

If such an extension nut doesn't ends far enough beyond the thrust washer - a short stub, in other words - you don't need to drill the spinner backplate to the larger diameter.

Although the shaft extention is not a solution to this particular problem. I have routinely run them on Fox stunt 35's for years, and heavy hubs as well. No problems so far.

I realize you found your solution but another possiblity are old Veco alum spinners, yes I realize the are not going to be commonly avalible but can be had. I have a nice stash of these and here is one I recently installed in this RC airplane.

The stepped back plate is just under a 1/16th and like to save these for the short shaft situation where a true spinner is kind of a must.

As already mentioned the Fox prop shaft extensions are not the solution for this but if any are interested as said the are avalible for either 1/4 or 5/16th shafts and either half inch or three quarter inch extension.

Here is one on my short shaft Fox 59 and they function fine:

John