Its called the subtle application of brute force .

Hope youve got a spare . 

Some of those chinese things with pressed in crankpins apparently have non hardened crankshafts , which bend , and unbend , easy .

Severely bent hardned one'd obviously likely crack or snap if through a matter of degrees ( A/C Vs Concrette )

A plate glass & feeler guage / packers , drill bits ( accurate sizeing ) and a piece of chalk or felt marker might get you somewhere .

Then youll be ready for the salt flats .



There is a vauge similarity in princaple at least .










Pieces me off when they rewrite history .
He'd dropped a amyl nitrate heart pill in the tank , and the TYRES were sawed off knobblies Rasped Round , as they were the toughest cases avaliable . Good old Kiwi Injunuity . Just about writen of by ' modern consumer society city slicker p brain addled disco turkey disco wombles .

One of the best mass produced props around are the APC designs. About half of them that I have purchased are a problem though, because they can't be bothered to drill the hole accurately. It is a shame, because the design seems almost uniformly excellent....

Dave



 

FWIW, the "hole" through an APC prop is supposed to be a clearance one , not a locating one.
It is drilled after moulding.  (If it needs to be larger to clear your shaft then you should drill it out.)
This is necessary because of the way they fill the props from the centre, which also provides optimal material flow and re-enforcing fiber orientation.
The hub is solid as the prop comes out of the mould, no through hole.

There is a recess in the rear of the prop that is moulded in.
They provide rings with the props that go in that recess to centre the prop on a shaft.

Pat MacKenzie

They provide rings with the props that go in that recess to centre the prop on a shaft.

   I have never heard or seen any such ring, including when we visited the factory. Where do you get them?

    Brett

I've written and scrapped two different replies to Pat's post. I disagree with the implication that they expect you to drill out all props (see their engineering notes) and bush them in order to be able to use their props.

APC ships bushings with the 1/2A props that I have purchased. Sizes like 4.2x4's.  Of the hundreds of other props and sizes I have purchased, mostly direct from the factory, there are no bushings supplied.  No, hobby shops are not "losing them."  They offer metric "adapters" (bushings), slow flyer adapters, and e-flight adapters. Nothing that would work with most glow props.

I maintain that they are making a superior prop, and doing very poorly at post-mold finishing. There does not appear to be a valid reason for that mediocre effort. If you set up to drill, you could set up to drill with a guide or fixture and get it done right.

This is actually not an unusual situation for machine shops. They put the lowest skill labor on cleanup, deburring, inserts, etc. Still, the consumers are not impressed, although they will have their apologists....

Dave

Sorry for the late response.
I am way more familiar with APC props for electrics, so I just sort of assumed that they provided the rings with all their props.

The explain how to centre their props on their web site. Basic idea is to open up the drilled portion but leave the moulded in recess in the rear untouched.
If that recess is too big then use some sort of spacer. Either one of theirs or something else

Details here, including the image below:
https://www.apcprop.com/technical-information/technical-support-advisories/

Centering Propellers on Motor Shaft

We recommend that APC propellers be centered on the motor shaft in the manner illustrated below. The through hole should be oversized for each particular motor shaft so that only the adapter ring (locating ring) centers the propeller.

If the recess is the correct size, then they suggest a tapered reamer to enlarge the hole only forward of the rear face:

Engine Shaft Hole Alignment

The propeller hub aft surface and aft hole are precisely defined during molding. However, post-molding shaft hole drilling may induce minor angular miss-alignment of the propeller with the engine shaft. This hole miss-alignment is avoided by use of a tapered reamer to slightly enlarge the propeller hole forward of the aft surface. This causes the propeller to precisely register with the engine shaft at the aft surface and hole.

Hope this clears things up (and shows I was not making anything up )

Pat MacKenzie

Not the large recess with the ejector pins in it, but the smaller counterbore, usually 3/8" ID.
That counterbore is part of the mould so will be centered. But the drilled portion is done post-moulding so won't be very accurate.

So if you want to use it with 1/4" shaft then you need a 1/4" ID and 3/8" OD ring.
And best to open up the drilled portion of the prop so that the shaft only locates off the adapter ring.

Don't know what to say as to why other are not aware of this, but I have known as long as I have been using APC props.
 Which has been a long time, I still have some of their piped 40 props I ran in 94.
I think they came on the market in the mid to late 80's? Perhaps it was mentioned then?

(Prop in the picture is an 11x5 non-electric one. The drilled portion is noticeably off centre relative to the moulded in counterbore.))

Dave is right ,the 6.5 -5,5.5,6&6.5 came with spacers,or as [ call then sleeves

Hi.

Go to their website, apcprop.com > Technical information > Technical support advisories > Balancing and installation OR Centering propellers on motor shaft.

The whole pro hole gate is quite well explained..

L

Correct, Dave, of course.
A simple well-guided drill could do perfect work but it looks like they do it by hand. L

When you read the info at website, they say that spacer rings come only with E-props.
They also have spacer rings separately available, in a molded frame like Bill said. Both in metric and in silly sizes. L

Both in metric and in silly sizes. L

  If only we had adopted metric, we could have invented the airplane, the supersonic airplane, landed men on the moon, become the decisive factor in two world wars, created the atom bomb and the thermonuclear bomb, put thousands of satellites into space, created the phone system and the internet, created the most fundamentally innovative form of government in 2000 years,  and be the basis of the world economy.
 
    Brett

Lauri, perhaps you’re unaware of the now-fashionable need for Trigger Warnings when discussing sensitive topics. 

The website just isn't a full explanation in short form of what they offer. Where they know you have to have a bushing (adapter), they may actually include it with the prop. And that does not show up in their listing of the three adapter sizes offered separately. The 1/2A props are in this category. Apparently, the gate (injection hole) has to be bigger in diameter than any conceivable 1/2A crank or bolt (like the Cox .125" 5-40) so to avoid having their customers search for mini-bushings, a set of bushings (adapters) comes with the prop.

Dave


PS--I'm just a SoCal boy, but what I heard is that the reason reindeers come in herds is so that the arctic winds won't blow them over. And that they have to stand up 'cause the frozen tundra would otherwise damage via frostbite the important reproductive apparatus. Any reindeer so anti-social to either leave the herd or get kicked out gets removed from the gene pool, and those so lazy or ignorant that it would lay down on tundra likewise gets removed from the gene pool. It is fortuitous that winter comes at least once a year to the Nordic countries, to allow this culling to happen frequently enough so that individual "anti-social" reindeers get rooted out, so to speak, before widespread mental deviations occur.* Therefore, since reindeer have not invented barns, indoor heating, electric blankets or jet aircraft which could shuttle them to Florida USA, and since deviant thinking is not in their nature to celebrate, their genome is destined to outlive the human animal, global warming notwithstanding. At least, that is what I heard....although this theory was immediately disputed in New York on social media, and was claimed to be a short-sighted, out-moded way of thinking, and had little to do with the truth especially because it did not acknowledge the root cause as lack of guaranteed reindeer wages regardless of employment, and the underlying cause as climate change. I don't really understand what that connection is--I just thought the theory had to do with frozen reindeer balls?

* Not all species were so lucky. Take the lemmings for example. When widespread social deviations occur within a population of lemmings, and they cannot master enough verbal calls to explain that there are not sufficient berries and lichens to eat unless they all participate in gathering them, the heretofore stable majority tends to run off a cliff just to get away from the deviant thinking. Thus, the population requires multiple generations to normalize behaviors, which despite the short gestation period and  massive birth rates, never quite overcomes the cycle.

[quote


PS--I'm just a SoCal boy, but what I heard is that the reason reindeers come in herds is so that the arctic winds won't blow them over. And that they have to stand up 'cause the frozen tundra would otherwise damage via frostbite the important reproductive apparatus. Any reindeer so anti-social to either leave the herd or get kicked out gets removed from the gene pool,..

I can see a similarity in behaviour here at SH.
But I'm in middle of Europe now, and I saw the sun briefly last week.
I sure miss Finland every now and then, especially reindeer meat. Yummy. L

     Rudolf was particularly good.

    Brett