Cutting a new thread in the prop boss....

J

John Denney

.
Oct 30, 2019
114
Hi all, I am having no joy finding a new machine screw to fit the 3/8 UNF hole in the prop boss. (the hole for the grease nipple). Just a thought....
would it make sense to cut a new thread - 10mm - as I can buy 10mm stainless or bronze machine screws that will fit? Has anyone tried to re-thread bronze - wondering if it is tricky?
The existing hole is about 9.25mm so it would only be a bit bigger... any engineers out there?
John
 
T

trevy_kins

.
Oct 31, 2019
230
Hi gang -- I never like to disagree with Steve, but from personal experience, John, unless you match the weight of the missing plug, you will likely get some vibrations. I lost my plug and used a dowel and some goop (marginally lighter than the weight of the plug) and it set up a very tangible imbalance and hideous vibration. The bosses are big but they are easily unbalanced. As soon as I replaced the plug, the vibration disappeared.



Trev (V2915)

From: AlbinVega@yahoogroups.com [mailto:AlbinVega@yahoogroups.com] On Behalf Of Steve Birch
Sent: March-15-12 3:06 PM
To: AlbinVega@yahoogroups.com
Subject: Re: [AlbinVega] Cutting a new thread in the prop boss....





Wouldnt worry about prop balance, that prop boss weighs a ton and the nipple wont make any difference.

Cheers

Steve B
 
S

stevebirch2002

.
Nov 8, 2001
1,818
Hi

When I had the MD6A in SC I also lost the plug and left a grease nipple in for a season, never noticed a thing. I would of thought the balance would of been on the blades rather than the boss but who knows....

Cheers

Steve B
 
T

trevy_kins

.
Oct 31, 2019
230
Steve – my guess is that your nipple probably closely matched the plug’s weight. Trev



From: AlbinVega@yahoogroups.com [mailto:AlbinVega@yahoogroups.com] On Behalf Of Steve Birch
Sent: March-15-12 6:18 PM
To: AlbinVega@yahoogroups.com
Subject: Re: [AlbinVega] Cutting a new thread in the prop boss....





Hi

When I had the MD6A in SC I also lost the plug and left a grease nipple in for a season, never noticed a thing. I would of thought the balance would of been on the blades rather than the boss but who knows....

Cheers

Steve B
 
T

tim_klynn

.
Feb 12, 2008
337
Why would you want to tap it to fit some weird (metric) size bolt when you can get the bolt you need here: 3/8"-24 x 3/4" Silicon Bronze Tap Bolt | Fastenal ?
________________________________
From: John Denney johndenney1@...
To: AlbinVega@yahoogroups.com
Sent: Thursday, March 15, 2012 8:27 AM
Subject: [AlbinVega] Cutting a new thread in the prop boss....



Hi all, I am having no joy finding a new machine screw to fit the 3/8 UNF hole in the prop boss. (the hole for the grease nipple). Just a thought....
would it make sense to cut a new thread - 10mm - as I can buy 10mm stainless or bronze machine screws that will fit? Has anyone tried to re-thread bronze - wondering if it is tricky?
The existing hole is about 9.25mm so it would only be a bit bigger... any engineers out there?
John
 
V

Vega1447

.
Oct 19, 2019
921
Albin Vega 27 Limerick
John I had same problem getting shear pins from US.

In the end a US member of this Group very kindly ordered them for me.

Maybe you could make an arrangement?

John V1447 Breakaway
John Kinsella
Mathematics and Statistics Dept
University of Limerick

Phone 0035361202148
Web jkcray.maths.ul.ie
 
J

johnadenney

.
Oct 30, 2011
221
That would be great... any volunteers? It looks like they are
readily available in the US... I have found a couple of companies that
will ship to the uk but I have to buy a box (1000 pieces!) .... I
wish I had not lost the blessed thing!
 
J

johnadenney

.
Oct 30, 2011
221
I have found out that 1/8 inch BSP (whatever that stands for) is the
same thread as 1/4 UNF - there is a whole world of thread sizes out
there that was blissfully unaware of! I can get 1/8 inch BSP Nylon
blanking plugs from ebay... it never ceases to amaze me how much you
need to know to be a yacht owner! Crisis over! (for now)
 
T

tim_klynn

.
Feb 12, 2008
337
I could get that and send it over to you. It would take awhile. Fastenal will probably have to order it, once it shows up here in

Boulder, I could ship it over. -Tim

________________________________
From: John.Kinsella John.Kinsella@...
To: AlbinVega@yahoogroups.com
Sent: Friday, March 16, 2012 3:02 AM
Subject: Re: [AlbinVega] Cutting a new thread in the prop boss....



John I had same problem getting shear pins from US.

In the end a US member of this Group very kindly ordered them for me.

Maybe you could make an arrangement?

John V1447 Breakaway

John Kinsella
Mathematics and Statistics Dept
University of Limerick

Phone 0035361202148
Web jkcray.maths.ul.ie
 
J

johnadenney

.
Oct 30, 2011
221
Many thanks Tim.... I have found some nylon plugs of the right size
on ebay and 316 stainless from a UK company that supplies oil rigs!
Phew - took some doing but I am ok. Thankyou very much for the offer
- very much appreciated.

John
 
A

araujo318

.
Dec 2, 2000
34
When my bronze prop plug was no longer usable, I replaced it with a threaded polypropylene pipe plug. The tread was close enough that it threaded in and out with no problems It lasted for more than ten years of being being put in and taken out to grease the prop. It eliminated all worry of galvanic corrosion and finding the right thread.

Jim
Vegabond 1870
Wickford, RI
 
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