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Mast Gate Screw Hole Too Big

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redeye
Master Marine Consultant

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3474 Posts

Response Posted - 02/01/2013 : 09:08:33

You almost want to drill out the mast gate to a hole size big enough that the tap does not tap it ( with it off the mast ). The SS mast gate metal is very hard and the aluminium mast metal is relatively soft.

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islander
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Response Posted - 02/01/2013 : 09:38:23

<blockquote id="quote">quote:<hr height="1" noshade id="quote">You almost want to drill out the mast gate to a hole size big enough that the tap does not tap it ( with it off the mast <hr height="1" noshade id="quote"></blockquote id="quote">
I disagree, Doing this will only result in very shallow threads cut in the mast resulting in loose screws again. The taps are tapered and if the holes in the mast are already oversized, The next larger tap will fit into the existing oversized hole without drilling. If the screws are 10-24 the next size up is 12-24. The aluminum is soft enough that hand turning the tap is not difficult.

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Davy J
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Response Posted - 02/01/2013 : 09:45:50

I'm pretty sure he meant the mast gate, not the mast.

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islander
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Response Posted - 02/01/2013 : 10:04:12

OK..My bad

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redeye
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Response Posted - 02/01/2013 : 12:29:51

<>

Y know ... given the tapering of the tap, I'd say you are probably right to just go ahead and tape it down and tap both ( the plate and the mast ) at the same time, especially with the other screw in place to help hold the plate in place.

And using a power tool with the tap bit.

Edited by - redeye on 02/01/2013 12:34:43

islander
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Response Posted - 02/01/2013 : 13:05:04

Ray, I miss read your reply, Some confusion here. You are correct to slightly oversize the holes in the mastgate. The screws don't have to thread into it. What I was talking about was the holes in the mast only.

Edited by - islander on 02/01/2013 13:22:23

redeye
Master Marine Consultant

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Response Posted - 02/01/2013 : 13:18:03

Well ... I'm just going over it all in my head alot cause I'm looking at replacing mine with bigger phillip head screws..

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CateP
Navigator

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108 Posts

Response Posted - 02/04/2013 : 06:50:34

Just bought Mr. Grip Screw Hole Repair and am going to try this out. I'll let you know how it works.

http://www.thehandyhardwareman.com/mr-grip-screw-hole-repair-kit.html

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redeye
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Response Posted - 02/04/2013 : 07:24:07

That might be a good way to go if you were replacing the grip once.. but you need to be able to put that screw back in many times.

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islander
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Response Posted - 02/04/2013 : 09:47:55

This is such an easy fix to do it the right way and this thread makes it sound more complicated than it really is and that quick fix will probably work for a while but....Hmmm, Nevermind, Its your boat.

Edited by - islander on 02/04/2013 09:50:25

Stinkpotter
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Djibouti
9014 Posts

Response Posted - 02/04/2013 : 10:16:33

<blockquote id="quote">quote:<hr height="1" noshade id="quote">...given the tapering of the tap, I'd say you are probably right to just go ahead and tape it down and tap both ( the plate and the mast ) at the same time...<hr height="1" noshade id="quote"></blockquote id="quote">
I'd specifically recommend against tapping the gate plates. (I realize that's not what Cate was talking about.) If you tap both the plate and the mast, the screw won't be able to tighten the plate down against the mast very well, and the threads in the softer aluminum might give when you try. (Either way, don't try too hard.) Plus, slightly oversized holes in the gate plates can allow tiny adjustments to let the slugs pass freely through the slot.

Edited by - Stinkpotter on 02/04/2013 10:38:24

redeye
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Response Posted - 02/04/2013 : 10:40:26

<< his is such an easy fix to do >>

Yepper.. I thought it was pretty funny the way the post gets carried away sometimes..

Tap it and put in some bigger screws.

"For God so loved the world...... That he didn't send a committee."

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Lee Panza
Captain

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465 Posts

Response Posted - 02/04/2013 : 21:01:31

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Davy J
 ...The most difficult thing about using the handtap, to me, is keeping the tap as perpendicular, to the surface, as possible until you get some threads started in the material. Once you have "bit" into the metal, cut some and then back off to clean out the tap.
<hr height="1" noshade id="quote"></blockquote id="quote">

Being able to hand-cut threads opens up a lot of opportunities for useful modifications on your boat, and hand-tapping is a whole lot easier with a guide:

(http://www1.mscdirect.com/cgi/NNSRIT2?PMAKA=06593016&PMPXNO=1759724&cm_re=ItemDetail-_-ResultListing-_-SearchResults)

Without a guide, even after the tap starts to feed itself you'll get irregular (weak) threads if it isn't kept plumb to the surface, both on its way in and on its way back out. This is especially true with aluminum.

It's surprisingly easy to hand-cut reasonably good threads with a guide, provided you've drilled the right size pilot hole. Turn the tap in until it starts to tighten up, then back-off a quarter turn or so to break the chips it's cutting, and then advance a partial turn past where you left off. Continue in this two-steps-forward-and-one-step-back fashion until it gets easy to turn; that's when you've gotten the tapered part of the tap entirely through the metal. I find that if I hold the guide with my thumb and index finger down where it's in contact with the metal I can keep it in position easily. The base of the guide is notched to sit perpendicular to a cylindrical surface like our masts or booms. The key to success is to apply pressure evenly on both arms of the handle to avoid causing the guide to shift.

A tapping guide, with a small selection of high-speed-steel taps, is a valuable tool to have around the house as well as the boat, but keep a thin coat of oil between the two parts of the guide because if it starts to rust and bind-up it's difficult to keep it stationary in position when you're using it (speaking from experience).

Edited by - on

Davy J
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Response Posted - 02/05/2013 : 07:12:06

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Being able to hand-cut threads opens up a lot of opportunities for useful modifications on your boat, and hand-tapping is a whole lot easier with a guide:<hr height="1" noshade id="quote"></blockquote id="quote">
Thanks for the tip. Heading to Harbor Freight for some other items this morning and have added this to the shopping list.

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CateP
Navigator

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108 Posts

Response Posted - 02/05/2013 : 07:46:43

For newbies like me, here is a picture of taps. They come in all sizes.

Here is a tap wrench. This is what you use with the tap to create new screw threads.

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redeye
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Response Posted - 02/05/2013 : 07:55:22

I did mine with a large power screwdriver/drill without any problem, ya just gotta be careful. Screwdriver setting. I was probably very lucky I didn't catch the wiring in the mast.

The hand method was probably a much better way to go.

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Stinkpotter
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Djibouti
9014 Posts

Response Posted - 02/05/2013 : 09:07:27

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by redeye
 I did mine with a large power screwdriver/drill without any problem...<hr height="1" noshade id="quote"></blockquote id="quote">Sorry--I can't imagine doing that.

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redeye
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Response Posted - 02/05/2013 : 12:31:05

<< Sorry--I can't imagine doing that >>

I basically didn't know any better...
Well it worked, and it happened kinda fast.

I've never hand tapped.... yet.

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vipermagic
1st Mate

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69 Posts

Response Posted - 02/05/2013 : 12:45:36

Tapping with a drill or similar is kind of like tapping a hole on 'hard mode'. I used to do it all the time in the shop - I don't have all day to tap 120 holes 1/4-20! - but its definitely easy to screw up. Mostly what happens is you wind up jamming the tap and breaking it off, and then you're in for a real good time extracting it.

When tapping with a straight flute tap (As in the picture CateP posted) once you get it started, you want to back the tap off roughly every half turn or so, for about a quarter turn- youll be able to feel the chip break off on the back of the cutting flute. This will help keep the tap from running into its own chips and jamming up.

That is a little overkill for tapping mast gate holes, though. The aluminum is so thin you won't really throw a significant chip. Run the tap as far down as possible - all the way to the top of the tap, if you have the room, in order to form the cleanest threads.

Also, you definitely want to use tapping fluid, especially on aluminum and really really especially on stainless. WD40 will work in a pinch, but something like rapid-tap really helps.

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islander
Master Marine Consultant

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Response Posted - 02/05/2013 : 13:21:58

<blockquote id="quote">quote:<hr height="1" noshade id="quote">I did mine with a large power screwdriver/drill without any problem, ya just gotta be careful. Screwdriver setting. I was probably very lucky I didn't catch the wiring in the mast.
<hr height="1" noshade id="quote"></blockquote id="quote">
Like using an Excavator to plant your Petunias...

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OJ
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Response Posted - 02/05/2013 : 20:26:09

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by redeye
 Yepper.. I thought it was pretty funny the way the post gets carried away sometimes..
<hr height="1" noshade id="quote"></blockquote id="quote">Yeah! imagine if we were all at Cate's boat live!

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