To "Turn" a Prop!

Hightower · 26 March 2005, 07:34

Recently purchased a new Alloy Mercury prop on Ebay and tried to fit it yesterday. Went on OK but as I turned it the flange that sits inside the gearbox housing was just touching (in one place).

Question: Is there anything wrong with turning the diameter of this flange down a bit, say 2mm off the diameter?

Andy

Cookee · 26 March 2005, 09:49

You may need a different thrust washer?

Hightower · 26 March 2005, 09:57

Thrust washer wouldn't help Cookee, it's the diameter and not the lip that I'm having a problem with. It only just touches and doesn't stop the prop from being rotated. It seems that the flange of the prop is very slightly off centre from the hub, quite a common fault of mass produced propellers I belive.

Maybe Julie could help on this one?

jwalker · 26 March 2005, 12:27

If it's touching in only one place, something is out of true.

If it is touching the gearcase in one place then the case is out of true. If the contact point is on the prop and as it rotates it wipes the inside edge of the casing then the prop or thrust washer is out of true. However, whilst skimming a wee bit off will be fine, the prop will be out of balance because it is running off centre in the first place.

Could it have taken a knock and the rear edge be distorted. If so, you may get it back into shape by careful use of a hammer.

Seriously.

Generally, you do not want to make the space between the prop and the case bigger than necessary because it will let too much exhaust out into the prop blades.

Jonny Fuller · 26 March 2005, 12:49

If it's such a small amount of interferance that you can turn it with ease, it can only be a thou or two, just file high point off!

jwalker · 26 March 2005, 16:42

Yeh, but it's going to be off by the clearance which should exist plus the couple of thou.

Jonny Fuller · 26 March 2005, 18:18

Keep it real, it's an ali prop on a 60 merc!

jwalker · 26 March 2005, 19:55

Hightower · 27 March 2005, 00:24

Thanks guys, I think the prop and the casing is a little bit out! Nothing I can do for the casing, but will take the prop into work and measure the runout with a DTI to determine if it's taken a knock or if it's at the hub. The prop has never been used but it could have taken a knock though. Only really wanted to know if it was OK to turn some "meat" off the lip, and I think you guys have answered that.

Andy

Jonny Fuller · 27 March 2005, 12:20

Quote:

Originally Posted by Jonny Fuller

Keep it real, it's an ali prop on a 60 merc!

My appologies, a 90 Merc.

It'll be fine if you turn a bit off, it really aint Johnny-rocket science, and if you remove a small amount of material from one side to get the desired clearance, with the hub being less than 4" dia, and made of a lightweight material, I don't think 'ballance' will be an issue at all.

Think how many props you see with huge chunks missing from the blade extremeties, which are on a greater radius, and it has to be fairy bad to cause any noticable vibration.

Hightower · 03 April 2005, 18:09

Anyone give me info on a local company (Portsmouth/Southampton) that specializes in prop refurbishment. I know about Steel developments and I know they're good, no offence but just like to deal face to face. I have a Stainless steel prop that needs checking out and conversion to merc fitment.

Andy

Pete7 · 03 April 2005, 18:19

andy, this guy is in Aldershot, but its really hard to find. don't know of anyone nearer unfotunately, perhaps you should start a business

http://www.streamlinedpropellers.co.uk/

Pete

Hightower · 03 April 2005, 20:47

I'd heard of a company called Propeller Revolutions in Poole, I think I'm in need of some rebushing as not only the hub not suitable for Merc fitment but is also running untrue similar to the Alloy one that I started the thread with, but much worse!

Andy

Nasher · 03 April 2005, 20:47

Andy

I use streamlined, as I can call in on my way home from work to his house close to the A31 if I arrange it with him.
I'm calling in to see him hopefully Tuesday evening if you want me to drop something off.
I'm picking up a set of 19inch blades for my Hustler coz I wrecked my 17inch standard OMC prop on the beach on Saturday.

Nasher.

Hightower · 04 April 2005, 00:16

Thanks Nasher, I'll do some phoning tomorrow.

Andy

Hightower · 06 April 2005, 17:37

Ok, I've turned my propeller and painted it. Now can any person answer me this techy question: Before I turned any meat off the prop I wanted to check the balance to see how it would change after the mod. I was very surprised to see that I needed a 7 gram counter weight on the hub to correct an imbalace on a NEW prop. What are the limits for prop balancing? Is it common for NEW props to be out of balance?

Andy