Mr Krabs build

[Xzessperated]

Wheres the strut at now?

17mm Tyler

[tylerm]

Heres some good info, i think anyway, that andrew g gave a couple of years back. It relates to SAW running.

http://www.rumrunnerracing.com/feforums/showpost.php?p=153380&postcount=8

[Xzessperated]

Heres some good info, i think anyway, that andrew g gave a couple of years back. It relates to SAW running.
http://www.rumrunnerracing.com/fefor...80&postcount=8

Yes and I think it might be very good advice in the case of Mr. Krabs.
There is not much that Andrew and Jay do not know. Thanks for that. I might file it down a bit deeper and see what happens because there is no way the sponsons want to leave the water yet. Not that I want a blow over but I want the boat to run lightly on those sponsons and they are still quite wet.

[Simon.O.]

Paddy, I will assume that you have not altered or moved the rear sponson boom so your frontal tub to table is still 26+mm ??
Do you know the exact AoA of the sponson bottom, if you do not have a good protractor handy just give me the height of the sponson bottom 100-150mm forward of the trailing edge. I will work it out from that.

It is amazing that the CoB Cg can go so far back and not blow over.
Things to help it blow:
More AoA on the sponson up to 6 degrees.
More AoA on the tub.........a bit hard now as you are at 17mm on the rear
Sh1tloads more power. THAT is the answer Paddy. Give it hell and blow it over !! Video is a must !!

Mine is about 4 weeks away I hope. It will be the Kiwi-Crab.

[Ub Hauled]

[Xzessperated]

Paddy, I will assume that you have not altered or moved the rear sponson boom so your frontal tub to table is still 26+mm ??
Do you know the exact AoA of the sponson bottom, if you do not have a good protractor handy just give me the height of the sponson bottom 100-150mm forward of the trailing edge. I will work it out from that.

It is amazing that the CoB Cg can go so far back and not blow over.
Things to help it blow:
More AoA on the sponson up to 6 degrees.
More AoA on the tub.........a bit hard now as you are at 17mm on the rear
Sh1tloads more power. THAT is the answer Paddy. Give it hell and blow it over !! Video is a must !!

Mine is about 4 weeks away I hope. It will be the Kiwi-Crab.

Hmmm. Food for thought Simon. I have seen twin nitro riggers. Maybe I should do a twin electric rigger. That should make Jan eat his popcorn faster.
I like the sound of Kiwi Krab. Would he be an All Black Krab doing the Haka.
Douggie will love this Haka...

http://www.youtube.com/watch?v=Nmy6OaZEAhE

I will get you those measurements at the weekend if that is ok.

[slimshady]

Mr Krabs nearly killed me the other night, my new battery arrived so I decided to test it on my new prop, metal this time but I think my research let me down a bit, the blades appeared to be braided to the shaft oppps.

When I spun her up to about 1/3 throttle I noticed a bizarre sound and a big bang so I shut down, the prop was missing all of the blades.

One landed in the loft ceiling one on the floor and I haven’t yet found the third.

I was less than 50mm from the lift off trajectory of the blades.

I will attach photos of the blades embedded in the ceiling later, when I can find the camera.

I think I brought a show boat prop.

Still looking for a good alternative because I strip props, plastic and now rubbish metal ones, wet or dry.

Oppps.

Slim

[Xzessperated]

Mr Krabs nearly killed me the other night, my new battery arrived so I decided to test it on my new prop, metal this time but I think my research let me down a bit, the blades appeared to be braided to the shaft oppps.

When I spun her up to about 1/3 throttle I noticed a bizarre sound and a big bang so I shut down, the prop was missing all of the blades.

One landed in the loft ceiling one on the floor and I haven’t yet found the third.

I was less than 50mm from the lift off trajectory of the blades.

I will attach photos of the blades embedded in the ceiling later, when I can find the camera.

I think I brought a show boat prop.

Still looking for a good alternative because I strip props, plastic and now rubbish metal ones, wet or dry.

Oppps.

Slim

Wow that was a lucky escape Slim.
Check out the link below. These are sharpened and balanced props and Steven gets them for East coast USA to Tasmania in 7 days so quicker for you I think.

http://www.offshoreelectrics.com/products.php?cat=45

If you can sharpen and balance your own go to the url below.

http://www.offshoreelectrics.com/categories.php?cat=46

You could PM egneg or andym on this forum if you want someone to do a prop for you. They both do good work.

[andym]

Yes both Chuck or myself would do props for you, I would like to se a pic of the one that came apart? Never seen or heard of that before and I have done some very thin props for very high power. Send me a PM with your current motor and esc and packs and I might even send one to you for cost.

[egneg]

If it were me I would get 2 or 3 as shipping would be about the same if you have the funds to do so.

[slimshady]

Thanks guys, my problem is I have an M4 Etti flexi drive from the motor coupling to the prop this consists of:

Starting from the very back of the boat (prop end):

1) M4 solid stainless steel shaft, length approximately 12mm

2) 4mm solid stainless steel shaft length approximately 41mm (passes through the two bearings in the strut set)

3) 3.175mm or 1/8" Flexi shaft length approximately 265mm I think when I brought it, it was 300mm long and I cut it down to suit.

I would remove the shaft and take a photo but I have used 603 retaining compound in the motor
coupling, so it’s going to be a Bitch to remove.

What I need to do is either convert the M4 part with some sort of adaptor or replace the whole shaft, I don't mine which but I cannot use plastic props anymore due to them disintegrating under load, or rubbish brass ones trying to kill me.

As I have found most metal props, brass in particular are 3/16" dog drive. And therefore not compatible with my M4 unit.

Can someone please help, I haven’t had Mr Krabs on the pond for a long time because of this, I also need a good turn fin, I have experimented with some custom hand made ones but they either flip mr Krabs or deck him into the side of the pond. (yes before anyone points out again my pond is too small but if I can get some slow set up runs the Norfolk boards are my next venture.

Thanks for bothering to read this.


Slim

[Xzessperated]

Thanks guys, my problem is I have an M4 Etti flexi drive from the motor coupling to the prop this consists of:

Starting from the very back of the boat (prop end):

1) M4 solid stainless steel shaft, length approximately 12mm

2) 4mm solid stainless steel shaft length approximately 41mm (passes through the two bearings in the strut set)

3) 3.175mm or 1/8" Flexi shaft length approximately 265mm I think when I brought it, it was 300mm long and I cut it down to suit.

I would remove the shaft and take a photo but I have used 603 retaining compound in the motor
coupling, so it’s going to be a Bitch to remove.

What I need to do is either convert the M4 part with some sort of adaptor or replace the whole shaft, I don't mine which but I cannot use plastic props anymore due to them disintegrating under load, or rubbish brass ones trying to kill me.

As I have found most metal props, brass in particular are 3/16" dog drive. And therefore not compatible with my M4 unit.

Can someone please help, I haven’t had Mr Krabs on the pond for a long time because of this, I also need a good turn fin, I have experimented with some custom hand made ones but they either flip mr Krabs or deck him into the side of the pond. (yes before anyone points out again my pond is too small but if I can get some slow set up runs the Norfolk boards are my next venture.

Thanks for bothering to read this.


Slim

Slim I know nothing about the M4 system but from reading the link below I think I get the idea. It seems to me all you have to do is make a sleeve to put between a normal drive dog and the 4mm shaft.
Have a look at the link below and tell me if I am correct.

http://www.offshoreelectrics.com/products.php?cat=106

I am not sure on the measurement conversion but if 4mm is bigger than the drive dog hole then you could put the drive dog in a lathe and drill the hole bigger to fit the shaft.

[andym]

Slim you are am engineer this should be a piece of piss mate,

[Xzessperated]

Slim I am going to be a bit blunt here but it is meant as help so do not take offence.
If I were you I would get rid of that drive system and put a conventional flex shaft system on that boat. Then you can use any of the Octura, Prather, ABC and other brand props on your boat. Yes it is a bit more money but money well spent.

[NativePaul]

Just beat me to it, Paddy? (exasperated) is right about the sleeve, I used to run 4mm shafts (unthreaded) and by luck the K&S brass or alloy tube that fits over a 4mm shaft is 3/16 od, if you have a long length of unthreaded shaft with a small threaded section on the end you cant use the Graupner stuff I suggested earlier, instead you need a standard grub screw type 3/16 drive dog, a length of the K&S tube, an optional short length of silicone watercooling/fuel tube, an M4 nut preferably nyloc, and last but not least your prop (forget those crappy ones made from brass sheet soldered onto the hub, there for tugs only, you want Octura, Prather, ABC, or Prop Shop. Astec is the place for Octura in the UK, but if I am buying a bunch of props I use OSE)

What you do is cut a length of the brass/alloy tube the same length or a little longer (not all props are the same length and are you sure this is the right prop) than the total of the prop and drive dog combo, slide the tube over the unthreaded shaft leaving enough room behind it for the optional silicone tube and prop nut (if you hit something the silicone can compress enough between the prop and the nut to disengage the drive dog), slide the drive dog up to the front of the tube then do the grub screw up fairly tight so it will leave a mark in the brass/alloy tube, then undo it again and file or drill a hole in the tube so the grub screw can go through the hole and grip the shaft, if you can keep the tube in securely in place on the shaft and make the hole with a file in a crosswise motion this will also give you a food flatspot for the grub screw to bite down on, then deburr the hole, slide the tube back on till you see the flatspot through the hole, put the dog over the tube till you see the flat through the grub hole then apply a drop of thread lock and do up the grub screw snugly, put the prop on followed by the silicone tube (if used) and nut, job done.

However, can you move the strut forwards at all giving you more strut sticking out the back and still maintain the shafts contact with both bearings? if not you may not have enough shaft sticking out the back for the dog, prop and nut, even without the silicone, in that case your only options are the continued use of threaded props or a new longer shaft, ETTI have realised that making gear with 4mm threaded shafts is a PITA but instead of going 3/16 they started making props to suit, so its not all bad news decent (looking) cnc alloy props are available in a small range of sizes and mostly 3 bladed, if your lucky there might be one suitable.


Edit, damn he just beat me the second time, I'm not as blunt as him, but I agree if you haven't got enough sticking out the back to adapt ditch it and get a 3/16 system.