Buck, how did that duropower conversion turn out, what kind of power did it make?

the prop in the pic is a dynathrust 16x8.i was getting around 73-7500 the last time i tested it i think.ive switched igns since then to the one with an advance on it but havent tried it yet to tach and see if theres any difference.the other item i need to change is the carb,its the zama 8-9mm.i need to switch to a 10mm but just havent done it yet either.the last time i flew this engine with the older ign it was on a GP G202 1/4 scale arf.it flew it ok like a spiort plane but no vertical really.it weighed 11.25 lbs RTF dry.i purchased a started 28cc stihl and worked on it instead.pic attached so you can get another look at a converted engine for ideas but its basiclly the same as my echo.

Buck, what size stock did you machine the prop hub out of?

most of my hubs i make from 1-1/2 to 1-3/4 6061 or 7075,not sure exactly but thats what the metal co i buy it from thought it was.i might be wrong about the 7075 and it might be the one thats closer to the 6065 but i dont remember the number.i like my face that the prop sits on a little bigger than some people.the prop hub i have extra the face is 1-1/4 in diameter and its 1-1/2 " long with a 5/16 bolt.the bolt hasnt been center tapped for a spinner setup.Its brand new but i bought it from someone else before i bought my lathe.if ya need one that fits all the way over the crank like tims in his pic i havent done one of those yet but scott at brillelli.com makes them for poulans all the time.maybe tim or someone else on this thread or do a search on hubs and maybe someone else makes them.im going to try my first one next week after i buy some new stock.

I make mine from 7075 or 2024. The 2024 is aircraft grade and has a little more copper in it which makes it stronger but it dulls a bit over time. The 7075 is the highest in strength and aircraft grade asdo and is stronger than the 2024 which is stronger than 6061. I have found that the 6061 doesn't hold threads as well and I have stripped the threads on hubs I have made from it. Not often but once is too much. I would go to some of the smaller job shops in your area and they will sell or give you their cutoffs or bar ends. Here is a sketch I found on RCU. This one is just threaded with no mating taper. I cut tapers on mine as I feel you get a good mating between the parts. On a smaller engine you can do it without a taper but on a larger engine I wouldn't trust it. Just imagine the way the hub would look on the sketch with a taper and you can see the benefits.

It would be so nice to have a laeth.

Yes, it would be nice to have a lathe. I have been looking at a 3 in 1 at HF for about a year now, trying to convince myself it is worth the $1,400.00 and that I would actually use it.

for this stuff, a 7" lathe will do everything needed on a conversion, doesn't have to be completely accurate since it's mostly one off stuff... I got my lathe for around $250 on craigslist lightly used (they only retail for around $400, but still that's a good deal), it'll make pretty much anything I need on conversions, I've made spark plug adapters, prop adapters, custom standoff's, I've machined the crank some to convert the dang left hand threads to right hand and turned off the rear crankshaft section. most of the rest of the stuff you want for conversions can be done with a dremel and hack saw, unless you want it to look perfect... remember, aluminum doesn't weigh too much, so you have to remove a lot of it to make it worth while, steel on the other hand is heavy...

I've seen the mill/lathe combo things on craigslist for around $600, and a couple like mine for similar prices to what I got

That is very true. However you can take a decent 7 inch lathe and tune it up to where it will turn parts without a taper. You still want your hub to run true as it can to keep wobble and vibration to a minimum. The larger lathes have more options available for them in the form of attachments and tooling is more readily available at very cheap prices. Power cross feed on the big ones is very handy. If all you intend on doing is prop hubs any lathe will do but if you want to do more bigger is better for me. But that is a decision left to the individual. You would be surprised at what you will end up making with a machine because you have one.

I was looking at something like this.
[link]http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44142[/link]

Or like this.
[link]http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=46199[/link]

I would do a search on Yahoo Groups for mini lathe and mini mill before I bought one.

Tim, why do you suggest that? Are those brands not that good or are there better deals out there?

go to littlemachineshop.com and look at the comparison chart for all the small lathes and mills.i did and i went with the cummins 7x12.it is a little longer than the same size HF and at least $100.00 dollars cheaper.i also got a load of accessaries that dont come with the other lathes.the thing i dont like is cummins is not west of the mighty missisip as far as i know so if somthing goes wrong my warranty issues are going to sucksince im in AZ.meanwhile there is a HF 40 miles from me so i could just take it to them.but im betting my lathe wont break down in the warranty period anyway(what if anything ever does) its uassally within the first week after the warranty runs out.(murphy).anyway,i used to be a diesal mechanic and have a degree in Agricultural and industrial mechanics so i can fix about anything.I only use course threads for my prop bolt in aluminum because its very hard to strip.fine threads belong in steel most of the time.take a weedy engine totally apart and see how many fine threads you have.Most all your bolts in an auto engine are also course thread and any 2 stroke air cooled engine.i just used a slide caliper on one of my hubs thats 1-1/4 inches long and theres no difference between either end so i know my lathe is running true at least for peices say up to 1-1/2" long.theres also a lathe forum here in the engine conversion section,check that out.theres been 2-3 people that bought the HF and said the space between centers was 2" shorter than advertised,but maybe they had the tailstock in it when thay measured or somthing else figured in.I waited for the Cummins truck to show up and paid $399 for mine with a lot of extra attachments that the others didnt have at the time i bought mine.

Tim,is there anyway i could tell what strength my aluminum round stock is without a hardness tester.say for instance the way the pigtails might peel off,or if the jaws leave a mark,somthing like that.i like the way your hub looks.im going to try one for my Mac 31cc im doing for my P-51.

Buck, have you had any problems with your Cummins lathe? I plan on buying one Monday unless a better deal comes along. It seems to come with a nice tool assortment. Is ther anything you would recommend purchasing with it?

that's the same as I have, I just have the one that Homier sells... if it were me I'd add the "rolling center" (more comonly known as a live center) to the list, they have a good price on it... better than I've seen online anywhere else

The Lathe at Cumings is a toy compared to the Harbor F. 8X12...that is really more like a 8X14 and is a very sturdy built lathe. Sure like my Harbor F #44859. Capt,n http://www.harborfreight.com

Captin, that part number is an 8 x 12.

Part #44859.... Here is a chart on Lathe comparisons. http://www.annisquamgranite.com/lathecomparo.htm I typed the wrong size...went back and corrected it.!!!! It is a 8X12 but more like a 8X14 ! Capt,n Read the comparisons. http://www.annisquamgranite.com/8x12ReviewPg1.htm

I'm ready to but the HF 8 x 12.

So if you guys see a coupon please let me know.

Page 14 of there current flyer at the bottom, $50.00 off. The good thing about HF is that I have a store about 30 minutes from me.

[link]http://www.harborfreightusa.com/usa/tabviewer/startBrowseBook.do?bookid=191&preview=&type=RET&si mple=[/link]

Well Captin, after reading the reviews you pointed me to, I went and order the HF 8x12, they say it will be in Friday and I can pick it up at the store, no shipping charges. I was almost convinced to get the 9x20 but my wife was with me and I quickly got steered away.

the HF is a much beefier machine especially for just a few hundred more.i was going to get that one but here they were 549 dollars plus i would have to buy the steady rest,faceplate,moving rest,drill chuck adaptor,ect..but i would have bought that one if i werent moving ect..plus i can pick it up by myself.But to answer the question i have had no bad luck with my cummins 7x12 and ive been using it straight out of the box with only 2 adjustments and i have it mounted on the rubber feet right now because i just havent bolted it to the bench i made yet.

what brand of scooter did these come off of.did you find the correct cc yet.

I don't remimber what brand scooter they were, some chinese made brand. The engine has a number 32 engraved on it. I guess it could mean alot of differant things but I am going to assume it means 32 cc. Besides it looks exactly like the one Box Car converted last year, which makes it a 32.6cc or 33cc as advertised by Duropower. I want to pull the head off of it anyway and I guess I could measure the bore and stroke. Duropower has several nice engines that would make great conversions even a couple of 4 strokes. They have a 51cc 2 stroke for $119.00, I am considering buying two of them for maybe a twin project down the road sometime.