advice on 1300mm 12s twin cat setup... NEED FEEDBACK PLEASE!!!

[uncle marvin]

MHZ 1380mm, running 12s twin elec. TP 5850's 990kv on Swordfish 240's an ready to purchase props an the MHZ drives are 1/4". Are people turning down the shafts to 3/16ths" to be able to have smaller prop choice? most 1/4" props start at 67mm an up, which seems much. advice an info is greatly appreciated.

[fweasel]

MHZ 1380mm, running 12s twin elec. TP 5850's 990kv on Swordfish 240's an ready to purchase props an the MHZ drives are 1/4". Are people turning down the shafts to 3/16ths" to be able to have smaller prop choice? most 1/4" props start at 67mm an up, which seems much. advice an info is greatly appreciated.

you can find ABC props in the 2.1" and larger range, which is 55mm for 1/4 bore. Something like a 2114 might be a place to start.

[paulejr]

Or , you could cut down a cheaper prop to the size you want, polish, balance, sharpen and maybe even try cupping and cutting the trailing edge by the hub. You can, kind of experiment on a cheaper alum prop to see what you can learn. Just a thought. Kinda like this : VXP BV642/2 42mm 1.6p 4.76mm B Cup Non Lift CNC Alloy Prop Boat Propeller MOD 3792769818350 |

[Bande1]

drill out a 3/16 prop to 1/4

[uncle marvin]

come to the same conclusion...... all summer try an try again. but i will know next summer.

[vvviivvv]

Speak to chris hoffman, i know he did have some X470 R blanks, get one of them cut down to 57mm

it's a hot setup so im assuming you want to go fast, later on experiment with some Abc props the 2115-17-45 is a nice prop on twins

[paulejr]

redrilling... huh, one needs a pretty good precision setup to insure it gets drilled properly, straight and square ...if you are off by more that a few thousands of an inch either way, the wabble will tear your boat apart (or drive line) before you can say fast electric.

[Bande1]

redrilling... huh, one needs a pretty good precision setup to insure it gets drilled properly, straight and square ...if you are off by more that a few thousands of an inch either way, the wabble will tear your boat apart (or drive line) before you can say fast electric.

not really hard to drill square with a decent drill press. then you're only drilling 5-7mm. then you will balance it afterward. Id be more worried about not leaving enough material on the prop hub.

[fweasel]

not really hard to drill square with a decent drill press. then you're only drilling 5-7mm. then you will balance it afterward. Id be more worried about not leaving enough material on the prop hub.

Square doesn't mean concentric too. New hole could be dead nuts on square and might never balance out. Safer and more reliable to just buy the right prop for the setup to begin with.

[Bande1]

Square doesn't mean concentric too. New hole could be dead nuts on square and might never balance out. Safer and more reliable to just buy the right prop for the setup to begin with.

he cant buy the right prop, that's the point here. sometimes you have to adapt and overcome.

[Peter A]

Perhaps the op is best to either get another set of drive shafts already turned to 3/16", or get his existing ones machined down to suit.

[paulejr]

well, he asked for suggestions , not stepping all over each other trying to be the only one right.

[uncle marvin]

I got up with Mr Hoffman, an he sent out 2 sets to get me started. Any feedback is still great. Thanks to all.

[fweasel]

I got up with Mr Hoffman, an he sent out 2 sets to get me started. Any feedback is still great. Thanks to all.

Chis is a good place to start. What sizes did you order?

[dasboata]

not really hard to drill square with a decent drill press. then you're only drilling 5-7mm. then you will balance it afterward. Id be more worried about not leaving enough material on the prop hub.

very hard to drill out a prop, tell me how you chuck it in a drill press ,, Iv try a few time , on a lathe and it's near impossible to do it square

[paulejr]

Yea, I just wait and buy one , centering the hub on the chuck is tedious for such a small part.
Getting the hub square and plumb to the jaws ..... You would have to build a jig to hold the prop and that, maybe tougher than just clamp it in a drill press vice , eye ball it and go for the gold.

[Bande1]

very hard to drill out a prop, tell me how you chuck it in a drill press ,, Iv try a few time , on a lathe and it's near impossible to do it square

put this on a drill press

IMG_20230605_071736.jpg

on a $30 milling table to aid in alignment with a .185 - .187 bit

51Y42HEZ9fL._AC_SX425_.jpg


practice with cheap plastic props
download (3).jpeg


you can use a regular drill press vice and rotate the press table as well.


a machinists centering bit would come in handy
713fpfXNpPL._SY445_.jpg

[dasboata]

yea lol good luck did you ever see a prop catch a drill bit , rip it out of that vise in a second , maybe those soft azz TFL junk but not Octura or ABC

[Bande1]

yea lol good luck did you ever see a prop catch a drill bit , rip it out of that vise in a second , maybe those soft azz TFL junk but not Octura or ABC

This is a fun hobby to have fun with. Tinkering, tuning, playing. It's not serious business.

[koen]

if you try to drill out a ss or beryllium prop keep a first aid kit close or 911

[Bande1]

if you try to drill out a ss or beryllium prop keep a first aid kit close or 911

why?

[photohoward1]

Just buy a turned down shaft. You are all over thinking it. Running 12s on 990kv motors is a lot of RPM. At least 45 volts right? 45k of RPM. I would start with about A 452 size. Those really big props can?t turn 45k. I?m not wrong either.


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[Notoriousone]

OSE sells 1/4' shafts stepped down to 3/16, I just got one 2 weeks ago. A much easier and better solution than drilling out the prop

[Bande1]

OSE sells 1/4' shafts stepped down to 3/16, I just got one 2 weeks ago. A much easier and better solution than drilling out the prop

came to say the same...easiest thing to do right here
https://www.offshoreelectrics.com/pr...e-cable-hp1300

[dasboata]

This is a fun hobby to have fun with. Tinkering, tuning, playing. It's not serious business.

well it's bad advise , & some one could get hurt trying !!!! & if you never tried to,,,, then you don't know

[Gottagobig1198]

This might sound stupid in regards to drilling out a prop to accommodate larger shafts but to those that seem to think its an impossible task... How do you think they get made? I mean sure if you start with billet you have to start with center but when you start casting like most props are you do need to drill that hole correct?

[Bande1]

This might sound stupid in regards to drilling out a prop to accommodate larger shafts but to those that seem to think its an impossible task... How do you think they get made? I mean sure if you start with billet you have to start with center but when you start casting like most props are you do need to drill that hole correct?

You get these people in every forum. I think they just like to argue. lots of things with sharp edges that get drilled. You can tape up the edges, you can drill before sharpening, you can use a lexan face shield on the press. It's just nonsense and acting like people are 5 year olds.

[T.S.Davis]

Most hobbyist don't have the tools or skills to drill out a prop and even if they did......why would they? I've got a whole shop full of tools. I ain't drilling a prop.

First the hub material left behind after drilling it out is very likely too thin to hold the blades. Especially at high rpm. These manufacturers came up with that hub thickness after years of failures. Speculation on my part to a degree but the hubs are of similar thickness on every prop. Accident? Wanna risk it with a cat that costs maybe a couple grand to build? If it throws a blade at those rpm it's like going to mangle something. Maybe the drive, maybe the boat, maybe the owner, maybe somebody standing watching? For what? To prove some dopes on OSE wrong?

Second......why do any of that when the stepped shaft solution quite literally costs an extra $5 per shaft? So $10 for the desired result on a multi-thousand dollar build. What the heck are we even talking bout? Just get the right parts and use them as manufactured for fewer question marks. On a 12s beast you want the fewest "is that gonna work?" questions as you can. You want reliable with no surprises. Too many moving parts to take chances you don't have too.

[raptor347]

If you don't want to go with step down shafts, I'd highly recommend 1/4 bore 2115-17-45 ABC's as a starting point.

[Gottagobig1198]

I like doing R&D in the field. I can take every tool I have or a roll of duct tape and a hammer but I will make it work and work well!