Home made propeller

[Glenno]

Hi all,
I am giving making a tubed cleaver for a 8hp Tohatsu a go.
Chopped blades of one of my Johnson 25hp stainless props and re-shaped, still a bit of fine tuning on blade shape to go.
Will make a jig and pitch block to weld blades on at 13 pitch and low rake.
Will keep pictures comming.

[Glenno]

Hi all,

I Have added a trailing lip to the blades, they all still need to be sharpened and polished.
I have also started on a pitch block (I decided it does not need to be that pretty as I will only be making one of these props)
I have weighed each blade and they are within 1gram (I will also ballance the prop once it is all together somehow)
I am gauging my pitch block off 3 props I have here which are all 13 pitch.
Although I have played, re shaped, modified heaps of props I have never made one from scratch so I am no expert at this, I know full well this could fail but would love any information or help from anyone who has done this before.
Just something I am enjoying playing with.
Cheers,
Glenno

[Fastjeff57]

Another nut like me! (Made several that way.) Be sure to leave LOTS of fillet where the blades are welded to the hub. (I didn't once and--whamo!--the blades broke off.)

Jeff

[Roflhat]

Awesome project

[zul8tr]

Quite a nice project. Do those blades have progressive pitch from leading to trailing edge at any given radius or a constant pitch at any given radius? If progressive pitch how will you get your desired 13" pitch?

[Glenno]

Hi mate,
Yep the blades are progressive pitch the whole way up the blades.
It will be 13 in the centre. I have three props here that are 13 pitch which I am modeling my pitch off, two of those props are progressive pitch.
If I get the pitch a bit wrong hopefully I go down not up, 12.5 would be fine but I am not sure how above 13 would go without modifying the little motor a bit.
If this prop is a failure, hopefully it looks cool and I will put it in my wife's display cabinet to man it up a bit!
Cheers,
Glenno

[Glenno]

Hi all,
Just finished the jig for holding the blades as I weld. We will see if it works, I know as soon as you tack weld stainless it moves, I am hoping to get this thing really accurate but at the end of the day if I fail at least I have learned a few more things.
I am wondering if I should polish the hub and blades before I weld it all together so I only have to clean up the welds and splatter. It would be easier while it's apart as it is only a small prop at just under 9 inch diamiter.
Thanks for the input so far.
Any input would be appreciated
Will keep you posted
Cheers,
Glenno

[Fastjeff57]

You'll have a tough time getting a grinding wheel in there no matter how you do it. Be sure to leave at least a 1/4 inch radius fillet weld AFTER grinding or the blades could snap off. (In other words, avoid excessive grinding.) A 1/2 inch fillet would be even safer.

Jeff

PS: Nice fitting of the blades to the hub! You might want to bevel that straight edge on both sides of the blade to improve weld penetration.

[Glenno]

Hi,
I will make sure to leave a good amount of weld on for sure, good info Jeff, last thing I want is for it to tear apart.
Just gave all members a quick buff to make final finish easier.
Cheers,
Glenn

[Fastjeff57]

One more thing I forgot to mention: I weigh each blade on a digital scale before welding. The heavy one(s) are ground (over a large area) on the back side to lighten them.

On angular positioning (since we don't own a machine shop!) you can use a large hex nut tack welded to the hub. A pointer aimed at every other flat (where they peak) will give you accurate results.


Good luck!

Jeff

PS: No one is gonna put Ron Hill out of business this way, but it sure is an interesting project. I've built five to date, two of which are successful.

[Ron Hill]

After You Weld the First Blade: How are you planning on knowing where to weld the next two blades?

[champ20B]

You'll have a tough time getting a grinding wheel in there no matter how you do it. Be sure to leave at least a 1/4 inch radius fillet weld AFTER grinding or the blades could snap off. (In other words, avoid excessive grinding.) A 1/2 inch fillet would be even safer.

Jeff

PS: Nice fitting of the blades to the hub! You might want to bevel that straight edge on both sides of the blade to improve weld penetration.

The wonderful DREMEL tool makes everything like this easy. That's what is needed here for precise work in corners. It will take time though.

[Ron Hill]

Send me your Bondo pitch block and the diameter of your hub, I can cast a few blanks.

Here are some pictures that might help you.

First picture is CNC'd aluminum pitch blocks and fixture to hold them.

We are now printing our pitch blocks from a 3D printer. Your Bondo will work fine and long as we put the blades on slowly and in wax. Welding blades on works, but it is a "HAIRY" deal and I don't weld...But the way we've done it, it tack weld in about three spots on each side of the blade, then check the picture, some of my early gauges were homemade, but they worked to compare blades to blades. I do know that a good weld will want you blades to be "VEED" where they attach to the hub.

Blue Prop Scan is a more modern and the sand paper is "HOMEMADE"...but works pretty good...

[Glenno]

Hi there,
Hi Ron, hope your well. With blade position I have put a centre punch mark on the hub (in picture below, I am pointing a scrap piece of steel at it). I got these three marks by just wrapping a piece of paper around the hub and then deviding the length by three, putting the paper back around then marking.
I also thought last night of welding a little tab to the jig at the very tip of the blades to align the lengths more accurately. I will also just tack it all then place it on a flat surface measure the distance between blade tips and also blade tips back to the flat surface. If it's all out I will bust the blades off and rethink it or adjust where needed. Thanks heaps for the info mate, I really need any help offered.

I am having a lot of fun with this project, for some reason propellers really fascinate me, probably because I love boats, water, speed, outboards, inboards, anything that floats.
Recently also vintage outboards.
Cheers,
Glenno

[Ron Hill]

A small error at the hub is nothing, but by the time it gets to the tip, it could be off a quarter inch. Before you do your finish welds, measure from point to point on the tips.....

What pitch, diameter are trying for? What s the hub size? What motor??? 30 Tohatsu???

I'll be 72 on 4/25/16, I've fooled with propellers all my life. I took the "Rope" tail off my rocking horse, when I was five, and put a Water Witch aluminum prop where the tail was. I also ground it thinner on my dad's grinding stone and filled the stone with aluminum....I only did that maybe 40-50 times more in my life...My dad was so fussy about only using his grind wheel to sharpen cutting tools for the lathe, then, I come along and grind aluminum and plug up the stone.

[Glenno]

Hi there,
I definitely will measure the tip to tip before I weld fully, good point.
The motor is an 8hp Tohatsu (slightly modified) hub size is 60mm od and I am trying to achieve around 13 pitch with low rake, diameter is 9 inch or just under.
I have raced 25hp and 550cc supersport but had a bad accident last year so sold off all my race boats, gear, props etc and happy to be alive.
Just want to make a prop for fun not really for race, unless there is a bathtub race somewhere.

Cheers,
Glenno

[zul8tr]

Hi there,
I definitely will measure the tip to tip before I weld fully, good point.
The motor is an 8hp Tohatsu (slightly modified) hub size is 60mm od and I am trying to achieve around 13 pitch with low rake, diameter is 9 inch or just under.
I have raced 25hp and 550cc supersport but had a bad accident last year so sold off all my race boats, gear, props etc and happy to be alive.
Just want to make a prop for fun not really for race, unless there is a bathtub race somewhere.

Cheers,
Glenno

8hp w/ 9 x 13p?

[sharpeye Mike]

Like Ron said vee out the 2 sides of the blades, this way you will get more penetration, best to get full penetration.

[Glenno]

Hi there,
I will definitely chamfer off both sides of the blades where they are to be welded to the hub to get better weld penetration.
My greatest concern now is controlling the pulling action created when welding stainless.
Cheers,
Glenno

[smittythewelder]

Are you thinking of peening the beads?

[Glenno]

Hi there,
I wasn't thinking of peening the beads, I'm not too familiar with the process and I don't have any mechanical means, I guess I could use some sort of pointy hammer or punch system though. Being a builder i am reasonably accurate with hammers and blunt instruments. I am hoping that I can hold the blades firmly enough with the jig to place a few decent tacks each side of the blades before I finish weld.
In saying that if this fails I will try other options.
I will be welding in about three days when things slow down a bit and will let you know what the outcome is.
Cheers,
Glenno

[sharpeye Mike]

Are you stick welding it or are you using a tig torch? If you have access to a tig torch go for it , it's a lot cleaner, you can control the arc and the heat better.

[Glenno]

G'day,
I am stick welding. Done plenty of stick with normal steel and also mig set up for alluminium (built a alloy boat as well) I am also competent with brazing. Unfortunately I have not had much of a go with tig, I would love to become competent using tig, can you get the volume of weld on with tig as well as with stick?
Cheers,
Glenno

[Fastjeff57]

I tack each side of the blade a few times before removing it from my jig to weld 'em up. So far, no distortion.

A MIG would also do a good job and is cheaper to buy than a TIG. Can you borrow one?


Jeff

[smittythewelder]

With stainless you need to know exactly what alloy you're working with, and choose the rod accordingly, the right number, the right suffix, etc. (Read the catalogs; I wouldn't make any recommendation here, this project is your baby!). It certainly is possible to make an acceptable stick weld, but if you aren't sure you can, you better practice on scrap, trying out your settings, your root gap, and so on. You'll want good long run-in and run-off tabs at either end of the joint so the arc is well established before it gets to the prop and after it comes off the end. Then when you cut off the tabs and grind the prop hub flat at either end, hopefully you won't see porosity and voids in the ends of the weld. Naturally you'll want to have the weld positioned as near to the flat position as you can (which is a trick given how the blade wraps around the hub!!).

Look up shot-peening. Somebody near you probably provides this service, well worthwhile in the interest of not slinging off a blade, I'd think.

[Glenno]

Hi there,
I know the hub is 316L but I'm not too sure what grade the blades are, they are off a 25hp omc stainless prop. I have 316L rods here in 2mm and 2.5mm, I did a small tack weld and it was really on, had to bend blade back and forth with force a few times before it came off.
Do you think the 316L sticks will be ok?
Keep in mind only 10 to 15hp will be driving this prop.
Cheers,
Glenno

[Fastjeff57]

That should be no problem at all--my props have to handle 70 hp. I use a carbon steel hub and stainless blades, with carbon steel welding wire (which makes clean up of the welds easier). The plan is to get a prop I'm fully satisfied with powder coated. So far, I'm still playing with them so....

Jeff

PS: I wonder if Ron Hill started this way...

[sharpeye Mike]

tig is affordable if you already have an dc welding machine, all you need is a tig torch, flow gauge and a bottle of argon gas and you just reverse the polarity, no switch on your welding machine! No problem, reverse the cables, your ground becomes your torch and your stick becomes your ground. If you can weld with an oxy and acetylene torch with a coat hanger you can weld with a tig torch. As for the material they used in making the prop you got your blades from, it's probably in the 400 series stainless and I know Ron is your best man for that question.

[smittythewelder]

I see that part of my suggestion above might not apply, the part about run-in and run-off tabs, because maybe you have that if your hub is a lot longer than the blade roots. I'm having a little trouble thinking about your project without thinking about an idea I had for turning old 2-blade racing props into 3- or 4-blade props; This would require sectioning cuts through the hubs of the donor props and then welding the hub edges. That would call for run-in tabs for sure, and some other tricks.

I think I understand from above that you are V-ing the blade roots to a point, for max penetration. If so, try to get the first pass on one side to penetrate clear under so that you see weld metal protruding all along the other side. With a little abrasive wheel in your Dremel motor, grind that protruding metal down until you have an unbroken length of solid metal to get your Side B pass to hook to. You don't want voids under the blade roots, preferably.

Good luck on it. I'd ask OMC about the alloy, or Ron. And I'd get the weld areas shot-peened regardless of horsepower.

[Glenno]

Hi there,
Sounds like shot peening is a good idea, does the process make the welded area more maluable and less inclined to crack?
And I will try to get no voids under weld foots.
I do like the idea of run in for the welds to bring the heat and penetration up to an even level for the entire length of weld.
Originally I was just going to weld the blades on with no v at the foot, lucky there are knowledgeable people here willing to help.
Thanks for the help so far!
Cheers,
Glenno

[smittythewelder]

Shot-peening has two separate beneficial effects. Read about it. Wikipedia is always a place to look first for this basic stuff.

[Glenno]

Hi all,
Well that was hard!!!!
Getting the blades perfectly positioned took a bit of fiddling, Ron was correct of course about measuring the tips. There is 185mm between each tip to tip measurement. Angles of the blades match one another.
Ron, your home made sanding wheel picture inspired me to make a similar but smaller version to machine the inside top of blade hub welds, not much of an option if you want to do it fast. The under blade welds are relatively easy to blend in.
So thanks for the pic ron, really helpful.

Still took a decent amount of time to clean up the welds and blend them in as I ran a few welds over each other to build up some mass. I did v the blades where they weld to the hub.
I will sort the hub over the next little while, then ballance then polish.
Cheers,
Glenno

[Roflhat]

Thats awesome, how are you making the inside of the hub?

[Fastjeff57]

Fabulous work, and you left what looks like sufficient fillets.

How do you plan to balance it? I use a homemade spin rig with weights temporarily duct taped to labeled blades (like balancing a ceiling fan). A bit subjective, but it seems to work.

Jeff

[Glenno]

Hi all,
I had 2 hours designated play time today so got some hub components fabricated. Need to press the components in and weld the main centre hub to the outer hub and then dowel the bushes in.
Having fun!
Cheers,
Glenno
Ps: Ron, how do you do your prototypes? They are a mission this way!

[Fastjeff57]

Careful with your alignment of so many pieces!

Jeff

[Glenno]

G'day,
Hopefully all the pieces should self alighn as they push into each other.
I will spin the prop before welding the centre hub to outer hub for sure to check if it's all aligned.
Cheers,
Glenno

[Glenno]

G'day,
Hub is going well.
Aligning the main centre hub took a bit of tinkering to get correct. The bushes centre themselves.
Just need to dowel the bushes, ballance and polish.
Ps: I will take the anode off and add a nose cone on the outboard.
Cheers,
Glenno

[fs5]

Nice job mate

[sharpeye Mike]

It sure is.

[Glenno]

Hi all,
Just finished balancing the prop (static ballance)
Thought a good way to test for vibrations would be just wack it in my drill.
Youtube of test prop spin on drill rig.

https://m.youtube.com/watch?v=fz3jtMb6tng

Cheers,
Glenno

[Fastjeff57]

Good enough.

Jeff

[champ20B]

The best way to balance your new prop is this:

1- Make sure your threaded rod or test shaft is straight and true by laying it on a flat surface and rolling it to see if it has any wobble.

2- If it is true, now get two carpenters levels and lay them parallel to each other edge up. Make sure they are level at both equal height and end to end (on blocks and shimmed).

3- Now take your threaded rod (test shaft) with prop mounted and lay it across the levels with the prop able to wheel in between suspended levels (like a railroad track).

The way to do this is to gently rotate the prop a few degrees at a time. Do this patiently and gently release so as to see if the prop will hold position without rolling forward or back. You can tape little pieces of material to determine the final balance any place on the prop if needed. This will be the best way to do this.

[Glenno]

Hi mate,
That's exactly what I did, great minds think alike! I did lay some thin steel on top of each level. The heavier blades drop to the bottom for sure. I even turned the threaded rod 180 deg in prop after I was happy with ballance to be extra sure.
Ps: I did parallel the the levels.
Cheers,
Glenno

[champ20B]

Excellent! Glenno, I would like to say that your project isn't just a home-made propeller....it is a fine and precise work of art that will prove successful. It looks perfect!

[Fastjeff57]

From testing of my own homemade props, I can see in your video that the balance is close enough. When the balance is off significantly, the prop will jump about enough to scare you!

Jeff

[Glenno]

G'day,
Thanks heaps guys and thanks for all the input.
All finished now and polished.
It's been a fun project, I am a builder (houses etc) so this has been fun as it's creative but very different than what I do during work. I always tinker and fabricate weird stuff and play with outboards constantly but this has really stretched me.
I don't have any race boats at the moment but I will put it on my tinny with a jacking plate and post the results here in kph and mph.
Either way it looks great on the shelf!
Cheers,
Glenno

[zul8tr]

Impressive job for a 1st.

[FrenchPhil]

Sweet Glenno. You need another cat project.

[Ron Hill]

It is too bad more people don't try to make thing for themselves.

Cliff Bedford owned an "OLD PEOPLE'S" home in San Diego. He raced boats, he was probably 60 plus years old. But by testing every afternoon, his boat designs changed the face of boat racing. Some of his propeller "CONCEPTS" are probably just being discovered today.

He was a "HANDS ON" old fart....probably had no formal education, but he did things himself and the results were amazing.

Glenno, you mentioned you had an accident....would you mind telling us what happened?

Lon Stevens, one of the greatest two stroke men in America, raced C Service until he had an accident. The accident left him with a hand I never saw, as he kept it covered with a glove.

The countless hours spent by Lon on the in line Six Mercury motors can never be calculated as I'm sure he worked on these motors in his sleep.

If you wish to build more propellers, I can suppluy you with blade and hub castings at a very reasonable price.

[Ron Hill]

G'day,
Thanks heaps guys and thanks for all the input.
All finished now and polished.
It's been a fun project, I am a builder (houses etc) so this has been fun as it's creative but very different than what I do during work. I always tinker and fabricate weird stuff and play with outboards constantly but this has really stretched me.
I don't have any race boats at the moment but I will put it on my tinny with a jacking plate and post the results here in kph and mph.
Either way it looks great on the shelf!
Cheers,
Glenno

That "Crappy" trim tab is for fishing, cut it off flush with the cavitation plate...

[Glenno]

Cheers Ron, it will be interesting to see how it performs. I will cut the skeg of for sure.

About my accident- the boat is pictured below.
I will post some footage of the boat running too.
It was kind of my fault for overpowering the hull which was designed for about 70mph. The modified 30hp yamaha power head on the 44xs leg and lower unit could push it up to 80mph or more if you were game. The circuit racing here in Australia is normally done in rivers which are not overly wide, so it's kind of like two straights, and a tight 180 deg left at the end of each straight. I had just gone passed the finish boy (end of race) in first place and the next microsecond I was doing cart wheels like a rag doll. When I popped up and turned around the boat was sitting upright but was a good 30 metres away from my tunnel and not far from the rock bank - 75mph exit speed. The boat apparently hooked right and stopped and I got flung exiting the boat dragging me out the left side of the cockpit. Both my legs where caught up under the dash - I am 100% now though. I have a young family so thought I would just stop racing for a while. Although the bug has not left me at all.
Cheers,
Glenno

https://m.youtube.com/watch?v=IDg45ezSvZE

[zul8tr]

Cheers Ron, it will be interesting to see how it performs. I will cut the skeg of for sure.

About my accident- the boat is pictured below.
I will post some footage of the boat running too.
It was kind of my fault for overpowering the hull which was designed for about 70mph. The modified 30hp yamaha power head on the 44xs leg and lower unit could push it up to 80mph or more if you were game. The circuit racing here in Australia is normally done in rivers which are not overly wide, so it's kind of like two straights, and a tight 180 deg left at the end of each straight. I had just gone passed the finish boy (end of race) in first place and the next microsecond I was doing cart wheels like a rag doll. When I popped up and turned around the boat was sitting upright but was a good 30 metres away from my tunnel and not far from the rock bank - 75mph exit speed. The boat apparently hooked right and stopped and I got flung exiting the boat dragging me out the left side of the cockpit. Both my legs where caught up under the dash - I am 100% now though. I have a young family so thought I would just stop racing for a while. Although the bug has not left me at all.
Cheers,
Glenno

https://m.youtube.com/watch?v=IDg45ezSvZE

Impressive performance for a 30hp Yami (I assume more than 30hp). What was done to that Yami? What gear ratio? What prop pitch? What peak rpm? What is the running weight of the total set up?

[Glenno]

True not 30hp, as many mods as imaginable to the power head. 1 to 1 gear ratio, props ranged from 13 pitch to 15 you can probably calculate the revs yourself, I never had a tach connected. Total set up with me in and including fuel was 212kgs or around 467pnd.
As you can see in the footage not running at full throttle down straights and very gentle on the gas out of the turns or she would try to flip- see turn 2, slightly too much gas.
Anyway sold that motor off separately to the boat, put a stock 25hp back on the boat and sold it to a guy from our club who just got a 102kph stock 25hp (25hp Tohatsu stock lower unit race prop nose cone) record for the kilo (1km one way-1km back average speed)
Cheers,
Glenno

[Fastjeff57]

Hey! I've have that video in my Keeper File!

Jeff

[Glenno]

Hi all

Just tested my home made prop at all transom heights from centre of prop shaft level with bottom of boat all the way down to standard full depth in 1/2 inch increments. Didn't seem to hook up (lots of cavitation even at speed 26mph on gps) only 4mph better than standard prop, oh well I had fun making it and it will look good on display, I knew from the start it may not work as well as I would hope.

My good old father always said "the man who never made mistakes never did anything".
Makes me feel better anyway, ha ha.

Youtube of test.

https://youtu.be/Ys9Usg7zt20

Please keep in mind I tested all heights in 1/2 inch increments.
From all my many previous race boats the props seem to cavitate until you get up on the plane then grab and your off.


Cheers,
Glenno

[Roflhat]

That's a shame, can you add cup?

[zul8tr]

Already has cup.

[Glenno]

Hi all,
I did make the prop with a tiny cup but it's near non existant. I have added more cup and I will try it again, starting at full height (prop shaft 1/2 below bottom of boat).
Cheers,
Glenno

[Glenno]

Hi all,
I added a lot more cup to the prop, runs heaps better!
Needs another balance and a polish now though.

Youtube of test two.

https://youtu.be/itiL0UEKKJY

26.5mph on crappy old heavy aluminium boat , not bad for a stock 8hp.
I would love to get it onto a better hull to see what happens, something with a running plank or a little tunnel, I won't go out of my way to find one though, I may be able to try it on my mates bathtub boat if he still has it.
I'm much happier now that the prop works well, nice bite even in turns.
Cheers,
Glenno

[sharpeye Mike]

26.5 MPH with an 8 HP motor on a aluminum boat to boot!!! Wow I think that is a success story. Nothing to cry about.

[Ron Hill]

We used to race 25 HP Johnsons with shifting gearcases. What we found in those days was funny. What we found you could not put too much cup in one of those props. I think you need to heat the blades and cup them a ton.

[fs5]

Sharpening the back edge of the cup helps them grip a bit better to mate.
Great numbers for a tinny.
It would crack on one of those little junior mono's.

[Fastjeff57]

Ron Hill is getting nervous!

Jeff

[Glenno]

Hi there,
That's funny, I don't think Ron is worried about a hack like me, he is more than welcome to take copies of this if he likes.
Cheers,
Glenno

[Fastjeff57]

It was meant to be a joke! You and I couldn't make a dent in his outstanding business.

Jeff

[Ron Hill]

I worry about everything, my wife calls it whining. I see so many people sitting on their asses doing what, I'm not sure. I love to see making things.

A gy came by the shop want wanted to borrow some props, as he said his buddies, seven of them, were going to Parker and wanted to try some of our Signature Propellers on their Mini Schiada's. So, I said , "SURE." I gave them about ten I thought would be good. The guy said, "I want to try that 10.25 X 20 five blade." I said, "That's way to much pitch and cleaver planes the boat like crap." He said, "Oh it looks so cool."

Bottom Line, I sold them several propellers, but the best ones were my 10.25 X 20 FIVE BLADE CLEAVER..........What do I know???

[Fastjeff57]

One hell of a lot more than the rest of us!

Jeff

[Steves Jem]

Nice Job. You don't get anywhere by not doing anything and waiting around for others. The secret to performance and success is experimenting, perseverance, determination and never giving up and willing to try new ideas. As you are in Australia you should consider chasing up one of the JT2 boats (10hp) to try your prop to see how it goes. That would give you a better idea on how the prop is performing. As regards your other boat Growler, I believe that this boat use to run a Yamato and currently holds the Australian 550cc Super Sports record. There is a thread on this boat elsewhere on this forum but the identity and whereabouts eludes me. There are a couple of You Tubes on this boat but I can not remember the link. If you still have this boat and setup the Australian 550cc Super Sports Championships are to be held at Raymond Terrace in May just after the Bridge to Bridge.

Regards
Stephen Medaris