Model Forum / Radio Controlled / Air Models / June 2004

And here are some answers:

Don't tap the prop hole, you need to ream it out just enough so you can
slide it on the prop shaft. Be careful not to go too far with the reaming.
The prop should have no slop as you put it on the prop shaft. I have used a
standard tapered reamer available at most hardware stores. It is a tool that
has a multitude of uses in the modelers shop so you should have one anyway.

You are welcome.

--
Red Scholefield AMA 951 District V

Dont know about the FAQ but do invest in the prop reamer. You dont want to
thread the prop, you just want to enlarge the hole. This allows you to
position the prop so that it can be level to the ground as the engine comes
up against compression. Saves you a lot of props this way on the less than
perfect landings. Drilling out the prop without making it off sided is not
easy. The prop reamer is a tool you will be using often in the future.

On 5/30/2004 11:06 AM Ted shuffled out of his cave and grunted these
great (and sometimes not so great) words of knowledge:

RC Universe  http://www.rcuniverse.com/  has an excellent selection of
forums covering quite a few topics.

Another site you can try is RCFAQ
http://web.archive.org/web/20030625052210/http://www.rcfaq.com/
Be aware that this is a VERY SLOW SITE.

And this wouldn't be complete without Allen's RC Links
http://homepages.ihug.co.nz/~atong/

I am ALMOST finished my first trainer (an Eagle 2) and have a couple of
questions to ask before doing so.

BTW --- thanks to all who suggested a Z bend + plastic connector for the
throttle. As you pointed out quite patiently, it DOES work well. A little
finicky, but that's part of the fun for me!

Here are my questions:

1. Can you point me to the FAQ for this group --- I should have asked this a
while ago

2. I need to install a basic 10x6 Master Aircrew prop on an OS 40SF
engine --- the whole in the prop is a smaller than the shaft on the engine.
Is it better to drill out the prop or is reaming a better way to go? Is it
necessary to buy a reamer made by someone like GP, or can I just use a tap
that you can buy at Home Depot? Typically, how many threads per inch are on
an OS engine shaft --- it seems to be 28, but this strikes as oddball
(1/4"-28 versus a more standard 1/4"-20).

Thanks

Don Tanner
Oakville, Ontario
==================
1. Not sure if there is a FAQ.  Generally accepted posting standards are
similar to most usenet groups; 'plain text' messages and no photos or other
binary attachments.  www.rcgroups.com and www.rcuniverse.com have good
beginner forums.  There are probably others but these are the ones I know.

2. 1/4-28 is a standard fine thread.  There is also a 1/4-32 thread but, in
models, I think it's only used for glow plugs.  Every engine I've seen has
fine threads on the prop shaft.  Most engines under .61 use 1/4-28 shafts
(assuming they do not have metric shafts)(I'm certain there are plenty of
exceptions).  My .61 to .91 engines (OS, ASP, Thunder Tiger) have 5/16-24
threads.  As others answered, you should get a prop reamer.  My brother
bought the Great Planes version and it seemed very dull.  It was hard to
work it through a Master Airscrew prop, and almost impossible to get it
through an APC.  I bought a Fox reamer, and when my brother saw how sharp it
is, he bought one and tossed the GP.  The prop reamer is the first GP tool
we've been disappointed with.

Regards,
Carrell

Comments interspersed below.

I can't - maybe someone else can.

You don't want to thread the prop onto the shaft.  1/4-28 is the correct
thread for the shaft, but the prop needs to be reamed to a clearance hole
for 1/4 inch.

I think a 10/6 prop from most makers already has a 1/4" hole in it.  If not,
any of the hobby shop hand reamers can do the job.  The problem with
drilling out the hole is making sure you are centered.  If you have a drill
press or milling machine and a center finder, this is no problem.
Otherwise, you can end up with an unbalanced prop.

In other words, you shouldn't have to do anything.  Will the prop "thread
onto" the shaft? If so, just run it down until it bottoms on the drive
bushing, then tighten the washer and nut down.  This will "strip" any
threads made in running it down, which is what you want.  Tighten and go
fly.

-- Mike Norton