rangerfredbob

My Feedback: (13)

ok, I don't have any hobby shops in town or close enough to work to go after work any time I want (they don't have the big props at that one anyway), so I'm wondering what the average prop center size is for what props? I have some 1" and 1.25" stock, the 15" prop I have has a 1" center and the 18" props are 1.25" or close enough, but what about the 16" props? I have a couple homelite 25's I'm going to convert in the near future and figured I'd ask before I made a not so great decision (I know some props would be fine with a smaller hub, but some could suffer)

also, what kind of lengths do you guys make the hubs to? the one I made for the 18cc I made around 1.5" long I think, seemed reasonable, luckily I had a 5/16" 24 through tap...

Thanks for the help!

buck1856

My Feedback: (49)

my hubs range from 1.50 - 1.75 inches in length.i personally wouldnt go over 2 in long,i would use standoffs instead.the bott shank of my hubs are about 1 inch diameter and then change to 1.25 for the prop to rest on, anything up to 30cc.over 30cc i like 1.5 up to 2 inch for the prop to rest on,like my zenoah g62,gt80,husky61 ect...the larger size engines the hub is the same length as the others.as per the threads i was told by a machinest and rcign i believe that course threads are better than fine.they grip better and dont strip out.on my smaller hubs i use 5/16x18 and 3/8x16 on engines over 40cc.ace sells all kinds of taps and dies seperatly usally less than a couple dollars a peice.the bottom thread just gets what the crank has on it for obvious reasons with loctite.

rangerfredbob

My Feedback: (13)

I've got a whole sleugh of taps, that's not a problem, it's mainly the material selection available, the largest I have available to me is the 1.25 I think, I'll check back at Fastenal and see if I can get any bigger... since I'm planning on getting a 50+cc engine soon... it was about $10 for a foot of 1.25" and $7 for a foot of 1" so that's not too bad

I used standoff's for my 32cc and just made the prop hub then the length of material I had at the time (it's a cowled plane)

one of these days when I have some free time I'll get onto those conversions, in the near future will be a 32cc craftsman and two 25cc homie's and maybe another 32cc craftsman, and maybe a chainsaw if I end up getting it...

av8tor1977

My Feedback: (6)

It's much cheaper here: http://www.aircraftspruce.com/catalo...ound6061t6.php and they don't mind small orders.

Browse the site, lot's of other goodies too. I've been ordering from them for years....

AV8TOR

mikenlapaz

Another source: http://www.mcmaster.com/ I have used 1.5" and watched some material curl away as waste but felt that the 1.25" was on small size for gas engines.

I read here that there is another series of aluminum that holds threads better than the 6061 maybe someone can share. Seem Ralph commented as to why he change series on his hubs.

buck1856

My Feedback: (49)

i found one place that sells 2.0 in diameter x 4 ft long for 40.00 plus about 12-15 for shipping.i think it was the 6061.im going to look again and compare with aircraftspruce that av8tor just mentioned,didnt know about them.im going to check with a metal co in phoenix and see what they sell metal for.im going for 2 in for 6 bolt WWI hubs and the larger size for the prop face of hub.i just bought my first lathe so its time to experiment.been a long,loooooooong time since high school.just made my first magnet sensor ring from a flywheel 2 nights ago.came out great.

rangerfredbob

My Feedback: (13)

ok, now I'm curious what size material I'm going to need for the prop hub on a 52 or 54cc engine, and what size prop I'll want to use, I'll give some specifics when I get it in the mail, but want some ideas before I got started.

thanks for the sourses, I'm going to check with our machinist from work to see what I could maybe get from him too

av8tor1977

My Feedback: (6)

Well, 2024 aluminum is stronger than 6061, but I really don't think it's necessary unless it's a "worst case scenario" in a given installation.

Buck... I used to buy from "Columbia Metals" in Phoenix. You might see if they are still in business as it's been a few years since I dealt with them....

One can often buy "drops" or "cut offs" from metal companies for a fraction of what the metal normally sells for.... (It's the pieces left over after cutting lengths for customers, that often go back to the smelter if someone doesn't buy them. They are often more than long enough for our uses.)

AV8TOR

buck1856

My Feedback: (49)

thanks av8tor ill look that up in the phone book.im also going to ask a few machine cos,metal works,ect..also the scrap yard.i read somwhere that sombody goes dumpster diving in the shops trash bins(recycle bins).

rangerfredbob

My Feedback: (13)

ok, just made an order from aircraftspruce... now I'll have another foot of 1 1/4", a foot of 1 1/2" a foot of 1 5/8" and two feet each of 1/2" and 5/8", should have got a couple more feet of 1" at that price... I shouldn't have to stock up for a while now

just looked up the engine I won the other day again, it's a 51.4cc, depending on how light it ends up I'm going to decide between magneto and gas/glow, I'm seriously doubting it's been converted before as it's not very new nor coommon, but it was cheap... I'll update on feasability after I have it in my hands next week. it's side carb (reed), rear exhaust, ball bearing crank and most likely not a name brand carb (have a few tillotsons that will most likely work with a custom spacer though).

as far as props, I was looking around and the DA50's and such call for a 22-10 prop, is that a good starting point? I did a search for 50cc on here and didn't find much converted in that size range so if anyone has any ideas on what to start with, it would be appreciated, I don't want to have to buy too many of them to play with at the price they get to up in that size...

Thanks!!!

av8tor1977

My Feedback: (6)

The DA-50 is pretty powerful. I would start with the 22 x 10 on yours, and see how it goes. If it loads the engine down too much, you can later go down to a 20 x 10. It really depends on the airplane, but I would go down in diameter if necessary rather than pitch, to keep the airspeed up.

AV8TOR

buck1856

My Feedback: (49)

I just rebuilt an A&M sachs 3.2,just need to make a little bigger hub i believe then i can test run it.Anyway,im starting with a 22-8 zinger pro to start with,then ill see what happens.I agree,im not going to buy 20 props to see which work best.Im going to use ones i have right now or i can pick up cheap from RC swap meets,auctions,ect...I also have a 22-10 zinger and a 22-6/10 zinger.Not the best props but a starting point.I might round the leading edge of the tips a little on the zingers also so they look more like the pro series.

rangerfredbob

My Feedback: (13)

ok, I now have the engine in hand and will share some more information on it. it's a 51.4cc Pioneer 970 Holiday II built in '71 or '72, I've only taken the carb off and clutch and oil pump and already http://www.acresinternet.com is off saying that it's a reed induction... I need to check the displacement tomorrow...

acresinternet says it's got ball bearings, along with the displacement were my interests in it... after I got it in my hands I noticed it is side intake and side exhaust, the muffler just wraps around.

anywho now to my question, there's left hand threads on both ends of the crankshaft for some reason, but the flywheel end is 3/8" so I could probably turn it down on the lathe and put 5/16 24 threads on it, that sound like a decent idea? of course I didn't realize it was left hand threads until I cranked on it for a while with the impact... there's threads in the flywheel to use a puller but I don't have anything that's 10-32 and long enough to use my puller... so I got frustrated and stopped for the night

have my 2" stock now so after I get the threads under control and adapter length to fit in the cowl down I'll make the adapter, but hobbytown stores don't generally carry either prop reamers or large props (or any generally helpful props sometimes for that matter) and the other LHS was closed when I drove by today... I'll check it out on monday

rangerfredbob

My Feedback: (13)

noone has an opinion on rethreading the shaft? should I go coarse or fine 5/16"?

ok, since this thing isn't exactly new, it has point type ignition, any simple way of shorting something and getting it to work like a normal coil? the condenser is connected to the same terminal on the coil as the kill switch, I don't have enough concentration to think it through all the way at the moment... if not I'll just go gas/glow since the goal is less weight and more power... just got the flywheel off tonight so it was easier to look at the ignition system...

was 12-24 a more standard size in the '70's? I think that's what's all over this thing, and is what is on the puller holes on the flywheel, luckily 10-24 held strong enough to pull it off... I imagine I'll be retaping a few things to 1/4-20 since 12-24 isn't readily available anymore...

haven't gotten as far as looking at the displacement or bearings, the flywheel being stuck wasn't helping since the case screws are under it...

av8tor1977

My Feedback: (6)

Hi,

There's two schools of thought about the threads. One is that coarse threads hold somewhat better in aluminum, others feel that fine threads do better because there's more per inch. Either one should work fine, just use Loctite on assembly. I never use the mag on my engines, so I usually make the prop adapter with am integral collar that extends back over the crankshaft, and has set screws. A little stronger that way, and virtually no chance of it accidentally coming unscrewed. (That might also make you feel a little better about having to turn the crank down to a smaller bolt size.)

Here's how I fixed the left hand thread problem on one of my engines: http://www.rcuniverse.com/forum/m_46...14/key_/tm.htm

As far as the ignition system, I don't know. I had an old Echo a few years ago that I just bought CH Ignitions "circuit board only; no coil" and used the original coil and it worked fine. I don't know if your ignition coil is separate from the charge coils of the magneto, and if so I don't know if it could be set up to work with just a battery and the points or not. Who knows what the voltage is of the magneto charge coils in the systems that used a separate ignition coil from years ago? I suppose you could put the mag back together and test with a voltmeter while someone turns the engine over rapidly. Also, "Kettering" ignitions, which is what we are talking about making here, are notorious for having a high current draw and so would need a large battery.

I'm running all my stuff, including a Poulan 42cc, on Gas/Glow. Keep the ignition stuff and you can always change it back to original, or go to CH Ignition if you don't like Gas/Glow.

Good luck,
AV8TOR

mikenlapaz

Drilling and tapping can be a pain.....................

Try http://www.mcmaster.com/ for 12-24 bolts.