Propeller removal - any ideas?

Parts of your broken puller, the screw etc, will be a good starting point for your bespoke item.

Flat plate is easy to buy from a steel stock holder. Ask to look in their scrap bin! If you talk to them nicely they may even cut the stuff up for you with their plasma cutting gear.

Granny sucking eggs coming up:

When blow lamping the prop, remember to protect your hull from the flames and rising heat. If you pay particular attention to this, it may save your gas bill.

73s de
Johnth
 
I broke one puller and bent another trying to get a prop off that must have been undisturbed for twenty years. I soaked the joint in WD40 and a couple of days later it popped off whilst I was fiddling about, fitting another puller!

The prop supplier confirmed the original purchase from their ledgers as 1987 and quoted me diameter, pitch, shaft diameter, taper and woodruffe key size!

Rob.
 
With heat, pulling, and hitting, my dad was still unable to get the prop off KS the other week. He ended up coming back another time (I wasn't there) and cutting the shaft with a hacksaw :eek:

Pete
 
Tout's near Sainsbury's, Commercial Road Portsmouth, will sell you the metal may even make bits for you.
Also Metal supermarket in Soton cut things to size I think.
 
When comparing the same tensile strength fixings, fine threads have more surface area in contact between male and female forms and a larger minor diameter which in turn make them stronger in tension than coarse threads .

As for pullers, if you look at high yield pullers such as hydraulic pullers, the barrel and the piston screw have almost without exception fine threads.
 
boggybrn said:
Thanks for all the suggestions so far...

It sounds like heating it up needs a more powerful torch than I was using . . . Any ideas where I could either get some plate?
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If you pass any where near Gatport Airwick, I can lend you a propane torch that is more akin to one of the nozzles from a Saturn 5 rocket. It has enough heat to make it seriously warm but not much more than 'dull red' unless you heat for ten minutes and it will go to 'cherry red'.

Regarding the puller, methinks a mini-Flywheel puller might be the way to go. If you are not familiar with this device, it is a thick (2cm) plate steel puller with three set-bolts at 120° with PCD's of about 100mm. I am sure it could be converted to suit. I have one in my workshop. :p

That said, one the screw has been 'warmed', you need two x 2lb hammers and tap on opposing sides of the recalcitrant hub (both at the same time) and it will pop off. :)

Have someone on hand with a large dirty towel to catch the very hot screw as it becomes detached otherwise it could fall on the ground and damage one or more blades . . . or worse! :eek: If you are working alone, wire-tie it with a brazing rod or similar, before you start heating, so it cannot fall. ;)

Trust me, I'm an engineer. You don't want to hit it too much with anything heavy as you will (could) shock and damage ball races elsewhere on the shaft.

If you need a hand, give me a shout.
 
dunmor said:
RUBBISH.

I've Worked In Engineering All My Life! And I Do Know What I'm Talking About!!!
Look At The Thread On Any Good Puller & it Will Have A Coarse Thread.:confused:
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The only puller I possess has what I would describe as a fine thread - don't know exactly what and I'm not going down to the boat shed to find out either. However, I've always thought that, all other things being equal, that a fine thread was stronger, so.....

1" dia, BSW compared with BSF, passing through a nut 1" long:
As it's all to do with the strength in shear of the thread at its' root, you just need to calculate the surface area of a cylinder 1" long x the core diameter.

BSF core dia = 0.8720, so area = 2.74 sq in
BSW core dia = 0.8399, so area = 2.64 sq in

There's no point going on to use the shear strength figure as it's only a comparison of like for like, the BSF thread has a larger area in shear so it's going to be stronger, by about 4%. I think. Corrections welcome.
 
You might want to disconnect the shaft coupling from the gearbox if you're wielding a hammer!

Worth re-stating that you're hitting the side of the prop boss with a hammer and using a heavy weight as an anvil on the other side. It's the shock wave across the taper that loosens it. Also, invest in some plus-gas releasing fluid. Infinitely better that WD40 for this.
 
RUBBISH
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The strength of a M10 x1.5 grade 8.8 bolt is approx 46400 N
The strength of a M10 x1.0 grade 8.8 bolt is approx 51600 N

as you'd expect the fine threaded bolt is stronger

However for grade 12.9 bolts the figures are

M10 x 1.5 ... 70700 N
M10 x 1.0 ... 78700 N

Conclusion for bolts in tension although the fine threaded ones are maginally stronger what makes far more difference is the grade

use High tensile bolts what ever the thread pitch, or simply larger diameter bolts

BUT for something like the central bolt in a puller ... the one you tighten to do the job ... you really do need the finest possible thread to give the maximum mechanical advantage. Pretty sure my puller has a fine non standard thread on its central bolt. but I aint going out in the cold workshop to look at it!
 
Ruffles said:
You might want to disconnect the shaft coupling from the gearbox if you're wielding a hammer!

Worth re-stating that you're hitting the side of the prop boss with a hammer and using a heavy weight as an anvil on the other side. It's the shock wave across the taper that loosens it. Also, invest in some plus-gas releasing fluid. Infinitely better that WD40 for this.
Click to expand...
The two hammer method has been mentioned a few times and I'd back that one. I tried it once to release the taper on a car steering joint and it worked first time even though I was using two different sized hammers.
 
wats stronger

VicS said:
The strength of a M10 x1.5 grade 8.8 bolt is approx 46400 N
The strength of a M10 x1.0 grade 8.8 bolt is approx 51600 N

as you'd expect the fine threaded bolt is stronger

However for grade 12.9 bolts the figures are

M10 x 1.5 ... 70700 N
M10 x 1.0 ... 78700 N

Conclusion for bolts in tension although the fine threaded ones are maginally stronger what makes far more difference is the grade

use High tensile bolts what ever the thread pitch, or simply larger diameter bolts

BUT for something like the central bolt in a puller ... the one you tighten to do the job ... you really do need the finest possible thread to give the maximum mechanical advantage. Pretty sure my puller has a fine non standard thread on its central bolt. but I aint going out in the cold workshop to look at it!
Click to expand...

do you lot want to step outside!:):):):)
 
Not a problem

Had the same problem, I had been trying all sorts of pullers for weeks when the yard owner / shipwright noticed me. I explained the problem and he disappeared for a few minutes and reapeared with two bolster hammers, he sat on a stool facing the prop held one mammer in each hand and brought them together hard at an angle of about 45 deg behind the prop a couple of times (the nut was off) and the prop fell off.

There he said, not a problem.

Don't you hate smart Alex's

Good luck.
 
seadog30 said:
Had the same problem, I had been trying all sorts of pullers for weeks when the yard owner / shipwright noticed me. I explained the problem and he disappeared for a few minutes and reapeared with two bolster hammers, he sat on a stool facing the prop held one mammer in each hand and brought them together hard at an angle of about 45 deg behind the prop a couple of times (the nut was off) and the prop fell off.

There he said, not a problem.

Don't you hate smart Alex's

Good luck.
Click to expand...

As my granny used to say, there's a difference between scratching your arse and tearing great lumps out.
Forget pullers and heat and plates and bolts and hot porridge and witchcraft.
It's called ringing.
It's the way.
 
Any small garage workshop or decent motor mechanic will have these items
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If only. When I wanted one to pull a bearing off a gearbox shaft all the local garage could offer was to fit a new/recon gear box!
(actually got it pulled off and a new bearing pressed on by a gearbox "reconditioners" in the end ... but any small garage ... nope)
 
Puller

It seems to me that the puller design is the problem. The often seen universal puller has 3 hooks to go to the back of bearing or prop. boggybrn has tried this type and busted a lug. It seems to me that you need 3 U bolts to go around the blades with 2 bolt heads per blade or 6 nuts on the flat plate.
Obviousl;y a U bolt will be far stronger in tension than a one sided hook.
Either use the wreckage of the commercial puller or start again using a flat plate.
Then as necessary invoke the heating trick. I gather in current temperatures you may be able to get the prop up to room temp. after many hours of flame throwing. Then apply carefully calibrated bashometers to the side of the hub.

You are not alone with prop problems. A friend was racing on Sun and heard a clunk under the hull. When he came to start the engine to back into the mooring pen there was no drive. It seems the prop has fallen off. In clear water you can see the shaft and threaded end. So some do come off. good luck olewill
 
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