Hybird MF14

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cape man
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Re: Hybird MF14

Post by cape man »

I'm swallowing spit!


The world always seems brighter when you've just made something that wasn't there before - Neil Gaiman

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OrangeQuest
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Re: Hybird MF14

Post by OrangeQuest »

I was just thinking of your build the other day and was wondering how it was going. Genuinely nice craftsmanship.
"that it isn't just an ordinary sort of boat. Sometimes it's a Boat, and sometimes it's more of an Accident. It all depends." "Depends on what?" "On whether I'm on the top of it or underneath it."
A. A. Milne

Chenier
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Re: Hybird MF14

Post by Chenier »

Thanks, all.

It's good to be away from distractions and back at boat-building!

Chenier
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Re: Hybird MF14

Post by Chenier »

Finished the main sheet blocks today.

Cross-drilling an axle for cotter pins that will hold it in place:

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All the bits and pieces, sitting on my shop drawing of the shell. The shell is sheet metal work, cut out of 1/16-inch bronze. The basic technique was described in the October, 2018 issue of Small Boats Magazine.

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Two completed blocks:

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They'll handle a sheet up to 3/8-inch diameter, and are loosely patterned after the blocks Sunfish come with today. As on the Sunfish, they'll be attached to the boom with a pair of padeyes that I get to fabricate next.

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cape man
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Re: Hybird MF14

Post by cape man »

Just amazing....
The world always seems brighter when you've just made something that wasn't there before - Neil Gaiman

Jeff
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Re: Hybird MF14

Post by Jeff »

Beautiful work!!! Jeff

Fuzz
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Re: Hybird MF14

Post by Fuzz »

cape man wrote: Wed Dec 08, 2021 5:41 am Just amazing....
X2 :!:

Chenier
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Re: Hybird MF14

Post by Chenier »

Here are the padeyes (or eyestraps) that will attach the blocks to the boom:

Image

The third one will anchor down a "leash" for the daggerboard to keep it in the vicinity of the boat after a capsize.

Finally, a set of linked eyebolts:

Image

In the MF14 plans the linked eyebolts attach the boom to the mast. However, I've obtained an early bronze Sunfish gooseneck to serve that function. These linked eyebolts will attach the sprit to the boom, just like on the Sunfish.

This concludes the hardware portion of the show. Up next: deep cleaning the shop a couple of times so I can varnish spars, daggerboard, coaming and other attachments.

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Netpackrat
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Re: Hybird MF14

Post by Netpackrat »

That's awesome. I would be interested in hearing about how you cut the grooves in the sheaves.

Chenier
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Re: Hybird MF14

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Starting with a cylinder that I cut to the right size, I outlined the boundaries of the sheave, as shown here:

Image

Then I attacked the blank with a series of knives. First attack was to plunge the 45º knife you see above into the blank as far as possible and then work it back and forth from shoulder to shoulder of the sheave. Wash, rinse, repeat until just short of the desired depth. This created a groove with 45º sides and a flat bottom. Then I used standard left- and -right cutting knives to cut away as much material as possible that wasn't needed for the rounded bottom. The top three knives in the photo below are the 45º flanked by the left- and -right cutting knives:

Image

(For those of you not used to lathe knives, the upper end of the knife is the cutting edge that I'm talking about. Most of these are double-ended, with the knife on the bottom end face down. The purpose of the bottom end may or may not have anything to do with the top end.)

In the case of the masthead sheave this was a two-part process. For the first half of the depth, the groove needs to accomodate the entire diameter of the rope as the whole rope has to drop all the way into the groove. So for that portion I used the left- and right- cutting knives out to the shoulders to get flat sides. Then repeated the plunge & cut trick to get a new 45º groove at the bottom with the right depth for the rounded bottom.

Once the groove was roughed out, I used the forming knives shown in the bottom row. The groove in the masthead needed to be 1/4 inch and, happily, the knife blanks were 1/4 inch so it was straightforward to just make a knife with a semi-circular end. That knife is bottom row, center.

Here's a different shot of the finished masthead sheave. Now that you know what to look for, you can see the upper straight sides and a little ridge where the rounded portion of the bottom starts.

Image

The boom gets so-called "racing blocks", where only the bottom half of the rope enters the groove. The shell has to leave plenty of room above the sheave for the top half of the rope. You can see this if you look at the boom blocks on the previous page. The groove in the boom sheaves is 3/8 inch wide, so I made complimentary left- and right- quarter-circle knives that were each 3/16 inches wide. Those are the two in the bottom row, left.

As you might imagine, there was lots of switching knives back and forth to get all this to come out right. It's what one might call "fiddly work". The two knives having narrower, rounded noses (bottom row, right) are traditional smoothing knives that I used to clean up some of the more egregious ridges and bloopers.

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