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Stainless Steel FreeHand?
Posted by: BCCTakayna (IP Logged)
Date: June 11, 2018 01:52AM
Category: Autopilots and windvanes

Hi Everyone,

Advice requested. I really really want to have the lower section of a freehand on my boat. The Monitor is great but its weight a long way aft and its a big hassle getting out of my dock with it.

Even if I could afford Mike Anderson's work of art I suspect shipping it to Australia would nearly double the price so sadly that does not seem to be an option. Sailing across the pacific to buy one in the states is a long term possibility but doesn't help now.

I have the drawings in the BCC manual to go off but I can't find anyone who would try and fabricate one in Bronze (which sounds like a bad idea anyway) and I don't have the skills to make patterns to have one cast so I am wondering if it would be an awful idea to have one fabricated in Stainless steel?

My boat is of an age where all the original fittings are bronze and I'd like to keep it that way but stainless seems the only option if I want the trim tab anytime soon. If I protect it with lots of Zinc anodes it should be OK shouldn't it? SS should be strong enough? I don't imagine the loads on it are that great are they?

Anyone with any thoughts?

Thanks

Jonathan

Re: Stainless Steel FreeHand?
Posted by: svshaula (IP Logged)
Date: June 13, 2018 04:28PM
Category: Autopilots and windvanes

Johnathon
Iím not familiar with the freehand, but of course have read about it in the Pardeyís books and on the forum here. Shaula has always had a lift up Aries. I guess youíre thinking of welding SS rather than bronze casting? How about welding silicon bronze plate which Iíve read is possible? Maybe bending or bolting?
Dan

Re: Stainless Steel FreeHand?
Posted by: Bil (IP Logged)
Date: June 14, 2018 02:46AM
Category: Autopilots and windvanes

The Larry Pardey-designed Mike Anderson-built Freehand Steering System has much going for it. That includes light weight, relative mechanical simplicity, and lack of the need for strong components. Those three things of course go together - because you don't need much mechanical strength, the Freehand SS components can be simple and lightweight.

The major underwater component is the trim tab. That's just a servo rudder to the BCC rudder, sitting as it does in the water flow just aft of the rudder. So the trim tab does not need to be a sophisticated NACA foil. The forces needed to turn the rudder are not huge and the direct connection to the rudder means you don't need toothed gear wheels etc.

All that means that the foil of the trim tab can be a shaped plank of teak (we encapsulated Zygote's trim tab in GRP after a teredo worm in tropical water found that teak, even though antifouled, too attractive to avoid).

The attachments to the rudder, the pivot of the trim tab, and the worm drive on the rudder head - all of which allow (1) the minor adjustment of the angle of the attack of the trim tab to counter the transverse prop walk of the prop when motoring; and (2) provide attachment for a simple tiller pilot (Z carries an Autohelm 1000 to drive the trim tab, the deal being that the forces involved in turning the servo rudder are tiny compared to the forces needed to turn the tiller).

And those two benefits, probably important in reverse order to what I have given, are high enough to justify just having the underwater parts of a Freehand SS. A tiny tiller pilot does a better job of steering than me most days. And for any shorthander, an inexpensive tiller pilot is a little superior to lashing the tiller.

I see no reason why you could not get those parts (or at least the metal ones) fabricated in stainless steel. Plain ss bar, threaded ss rod, and ss plate are easy to buy and work (or have fabricated). The factor to watch is related to galvanic action and whether you want to add to more ss to whatever mix of metal you have below water.

On Z, the rudder pintle/gudgeon set and the prop are bronze (the prop passes for bronze, goodness knows what it really is!). The prop shaft is ss. I have sacrificial zinc anodes on the prop shaft (a fixed prop) and on the lower gudgeon set. I recently added a tiny shaft zinc on the trim tab axle (bronze and seemed to show a little metal loss at last haul-out).

I conclude that you could fabricate the same parts in ss and likely just add the same additional chunk or two of zinc.

BCC 116 Zygote,
Scarborough Marina, Moreton Bay, Queensland, Australia

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Re: Stainless Steel FreeHand?
Posted by: John Cole (IP Logged)
Date: June 15, 2018 06:14AM
Category: Autopilots and windvanes

I think it would be advisable, if you DO manufacture your own, to settle on a royalty payment to Mike Anderson.

Alternatively, as the product is light. and it really is, purchase direct from Mike, the manufacturer. You will them receive a proven product. [www.andersonboatworks.com]

John Cole
[www.coledata.com]

Re: Stainless Steel FreeHand?
Posted by: BCCTakayna (IP Logged)
Date: September 16, 2018 04:09AM
Category: Autopilots and windvanes

Well, I have now received my bare castings from Mike Anderson, after a long and patient (on his part) email thread.

Sadly the entire unit was way beyond what my budget could go to but Mike made the generous offer of the castings and some plans at a price I could almost afford and so I jumped at his offer. Iím now starting to source some bronze rod and plate, some delrin to make bushes, and bronze bolts. Iím itching to get started but there are a couple of jobs ahead of it in the queue.

Thank you John for the prompt and thank you Mike for the castings and the help

Cheers

Jonathan

Re: Stainless Steel FreeHand?
Posted by: johnpurins (IP Logged)
Date: September 17, 2018 02:05PM
Category: Autopilots and windvanes

The backstay bearing of my Freehand steering gear had incurred severe UV degradation and so I machined a replacement. I didnít have affordable, ready access to a lathe and so used a drill press with a live center attachment. This, in essence, is a vertical lathe.

As shown in the attached photos, some nuts, washers, lock washers, threaded studs and aluminum stock serve to control cut depth and dimension. A couple of files, the appropriate drill bits and some wet & dry sandpaper enabled me to machine the replacement backstay bearing.

The hardest things to find were the live center lathe attachment and the appropriate Delrin stock. Here are two links that will help.

Drill press lathe attachment: [www.amazon.com]
Delrin stock: [www.professionalplastics.com]

The Delrin stock required for one backstay bearing is 2 pieces of 1Ē Black Homopolymer cut to 2Ē x 3.5Ē with dimensional cut tolerance of +.031/-.000. The black Delrin has much better UV resistance properties than the white.

Due to Professional Plastics minimum order requirements, I was able to buy 6 of these plus one 4Ē x 11.75Ē piece, to replace the bowsprit fid, at no additional cost. (My bowsprit also had UV issues)

In the attached photo of the original white bearing, itís clear that the UV degradation has severely affected the upper and lower collars where the 4 machines secure the two halves together. As a result, I increased the size of the collars to provide more material. You can see the difference between the original white and new black collars.

Attached is a CAD drawing of the new backstay bearing with the increased collar size. Also attached is a step by step description of the procedure that I used to machine the new bearing.

When machining the Delrin, use the lowest drill press speed. Also go very slowly and use plenty of lubricant when drilling and tapping Delrin. A solution of 25% liquid dish soap and 75% water works well.

Here are Amazon links to the files that were used:

[www.amazon.com]
[www.amazon.com]

Procedure:

1. Finish sand each 2" x 3.5" mating surface with 320 wet & dry
2. Scribe center lines of 4 holes from bottom edge of bearing + 1/64" (allowance for finish sanding)
3. Drill 4 3/8" holes with forstner bit to a depth of 1/2"
4. Align & clamp both halves of stock in drill press vise
5. Drill 4 5/32" holes through center of countersunk holes (tap size hole for 10-24 machine screw)
6. Drill 4 13/64" holes through center of countersunk holes (clearance size hole for 10-24 machine screw)
7. Tap 4 5/32" holes for 10-24 machine screw (use drill press for tap alignment)
8. Fasten both halves of bearing together with 4 10-24 3/4 machine screws
9. Sand top & bottom of bearing with 320 wet & dry until true (do not exceed 1/64" bottom material removal)
10. Drill 1/8" hole on centre axis of bearing top to a depth of 1/2"
11. Drill 3 holes around center axis of bearing top to accommodate 3 chuck set screws
12. Drill 9/32" on centre of axis of bearing bottom to a depth of 2"
13. Chuck & centre bearing in live center & chuck
14. Adjust cut to 1 3/4" + 1/64" (allowance for finish sanding) & turn stock to round
15. Adjust cut to 1/2" + 1/64" (allowance for finish sanding) & turn bearing centre spindle
16. Finish sand bearing on sides to design dimension (do not exceed 1/64" material removal)
17. Adjust cut for saw to cut top bearing to size + 1/64"
18. Turn bearing to cut to a depth for 3/8" (leaving 1" to saw by hand)
19. Chamfer circular bearing edges
20. Remove bearing from chuck & live centre & saw bearing top to size
21. Finish sand bearing top (do not exceed 1/64" material removal)
22. Drill remaining portion of 9/32" along center axis



Edited 1 times. Last edit at 09/17/18 02:12PM by johnpurins.

Attachments: Raw stock.jpg (388kB)   Bearing stock.jpg (188kB)   P1000123.jpg (344kB)   P1000124.jpg (554kB)   P1000125.jpg (483kB)   Old & new bearings.jpg (275kB)   Drawing.pdf (43kB)  


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