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-   -   Pre Made Panels That Can Stand Up to Engines Pushing Them? (https://www.cruisersforum.com/forums/f55/pre-made-panels-that-can-stand-up-to-engines-pushing-them-258648.html)

jimbunyard 10-12-2021 06:36

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Hard to imagine that you can do it more cheaply, or strongly, or quickly than by using .375" aluminum, which drills very easily indeed. Corrosion issues are also dealt with rather easily; commercial, specific products are available, us cheapskates just use teflon based pipe dope...

The outfit suggested previously,

https://www.midweststeelsupply.com/s...1aluminumplate

lists 6061 aluminum, 3/8" X 36" X 48", enough for both mounts, for for 279.03. I assume you can get two pieces 36 x 24 or 18 x 48 for the same price, if shipping size is an issue...

rslifkin 10-12-2021 06:49

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
If you need another source for pre-cut metal parts, I've ordered stuff from both Metals Depot and OnlineMetals with good results. I don't know how fancy either is willing to get with cuts though, I've only ever gotten rectangles or just cut lengths of material.

s/v Jedi 10-12-2021 07:16

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
I buy aluminum here and they can cut any thickness: https://www.onlinemetals.com/en/buy/...um-sheet-plate

That said, I would use Coosa board and fiberglass to manufacture these brackets. Nothing easier than tabbing with 1708 to the required strength and a completely inert product that doesn’t require any fasteners, just some UV protection.

jimbunyard 10-12-2021 19:57

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Have not used the source to which I linked, so I can't vouch for anything accept what is available online. I have used Metal Depot and Online Metals, and while their service is good, their prices are generally at least double, as is exemplified by the 574.00 price for the same item that can be (supposedly) had from Midwest for 279.00...

As for making the part from coosa or aluminum, the only way I'd even think of using coosa is for the 'slider' itself; the likely life span alone of a composite-only construction in that application would prevent me from building it; the transition from tension to compression across the vertical span of the 'bracket', even when at rest, is exactly the cause of the premature failure of many composite parts. I am assuming the vessel is intended for open ocean use...

And then there's the construction time, three days minimum for a properly (as far as that's possible) built, (edge finished, bolt-hole cored, painted) versus less than a day for all aluminum/UHMW bullet-proof construction, (the way I figure it 172 holes if you overkill it with 1/2 bolts [pilot holes necessary], 86 if you use entirely adequate 3/8 or 5/16 bolts, so 2 or 4 hours of drilling, an hour for cutting if you have a circular or table saw, and an hour or two for assembly. Contrary to popular belief, raw aluminum needs no 'finish'.

I doubt the weight 'savings' between an adequately-glassed composite structure and an aluminum one will amount to that of a six pack.

Leaving aside the relative ease of repairing or changing the aluminum versus a fiberglass part...

Chotu 11-12-2021 04:12

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Quote:

Originally Posted by s/v Jedi (Post 3535016)
I buy aluminum here and they can cut any thickness: https://www.onlinemetals.com/en/buy/...um-sheet-plate

That said, I would use Coosa board and fiberglass to manufacture these brackets. Nothing easier than tabbing with 1708 to the required strength and a completely inert product that doesn’t require any fasteners, just some UV protection.

That’s what I’m planning, but using Extren 500 (a superior product to Coosa) which is a polyester version of what everyone calls G10 on here, that I’ve used extensively on my boat already. The davits are made from it, for instance.

I can’t fillet/glass it to join though because there is a lot more to this than creating a simple part.

I have to create vibration damping so I’ll need to bolt things together like the design idea Jim Bunyard had. Between the bolts/plates has to be some rubber sheeting to quiet down the awful engine noise I had previously. But the rest of the design stays exactly as he had said.

Im just substituting a better (lighter, no corrosion, no pitting, better paint adhesion, easier to machine) material for aluminum.

And I FINALLY found some in stock, too just a day’s drive away!!

hpeer 11-12-2021 06:26

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
I will link it again

Joseph Fazzio, Glassboro, NJ

WILL SHEAR UP TO 1”, or saw cur if you prefer.

https://www.shopjfi.com/steel-services

Half the price of online metals.

Chotu 11-12-2021 07:14

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
2 Attachment(s)
Quote:

Originally Posted by jimbunyard (Post 3535371)
the transition from tension to compression across the vertical span of the 'bracket', even when at rest, is exactly the cause of the premature failure of many composite parts.

Jim, can you expand on this a little?

I want to make sure I’m not missing a key failure point which it sounds like you’re expressing.


I’m having trouble picturing where you are saying the stress problems are in this post if it’s fiberglass.

Keep in mind, it’s not just “fiberglass”, it’s engineered composite structural members I’m talking about using. Exactly the same as the davits we all designed together on here. Remember those? I was looking at aluminum but finally went with Extren 500 (like a polyester G10).

We used 1/4” tubing of this material for the davits. This would be 1/2” plate.

Here are the physical properties for both materials for quick comparison.

jimbunyard 11-12-2021 08:33

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Quote:

Originally Posted by Chotu (Post 3535561)
Jim, can you expand on this a little?

I want to make sure I’m not missing a key failure point which it sounds like you’re expressing.


I’m having trouble picturing where you are saying the stress problems are in this post if it’s fiberglass.

Keep in mind, it’s not just “fiberglass”, it’s engineered composite structural members I’m talking about using. Exactly the same as the davits we all designed together on here. Remember those? I was looking at aluminum but finally went with Extren 500 (like a polyester G10).

We used 1/4” tubing of this material for the davits. This would be 1/2” plate.

Here are the physical properties for both materials for quick comparison.

The problem is with a laminated structure, not with the structural properties of fiberglass itself.

My point is that the load at the top of the bracket is in tension, while the load at the bottom is in compression, thus creating the tendency for the structure to 'unzip' or delaminate from the top down at the intersections of the 'standoffs' and the slider and mount plate. Given the motion of a 50 vessel in certain wave conditions, I'd just have problems relying on hand laid joints in those conditions (among other things), especially over 'X' hours at 'X' condition.

When you brought up the Extren 500, my first response was to look into the specs and manufacturing process.

When I read 'pulltrusion', I almost threw up my hands, since that brought to mind pulltruded garden tool handles, which have unidirectional strands pulled axially over a round die, and are prone to splitting under load.

But I read on, and the Extren is not so simple, and is constructed with a combination of reinforcing fibers.

So it gets the 'JB overkill' seal of approval.

My only caveat would be that, since it seems about 25% less 'strong' than 6061 aluminum, I'd go up to half inch thickness, with at least 3/8 bolts and thick fender washers.

I'm not so sure that you'll get any real benefit from using any 'sound damping' material between the structural members; it'll certainly allow movement between those members, which does not bode well for elements built with polyester resin as a binder.

I'm thinking that getting a reasonable close fit of your slides will cut down/prevent rattling, and perhaps some kind of solid rubber block cut to fit tightly inside the standoff, might result in a better damping effect.

Where to some up with a solid block of rubber that size is more of an issue, maybe cut up tires glued together as a test? I've seen castable, 2 part urethane rubber for engine mounts available online, but I 'shudder to think' at the cost for 5 gallons of it...


I don't remember the davits, but am curious. Do you remember the title of the thread, or have a link?

Chotu 11-12-2021 10:46

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
I’m definitely at 1/2 inch for the Extren. I was not going to go any thinner than that. I have been using the stuff and I know that would be the right sizing. Even without the math.



Here is the davits thread where we reasoned out the Extren 500 material last year sometime.

What a fun thread!

And the results are installed on my boat in real life.

https://www.cruisersforum.com/forums...rs-243278.html

At the end of this thread, which we are almost at I think, after I get these motor mounts installed, I’ll take a picture. The result of the thread.

Chotu 03-01-2022 11:23

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Structural question.

The “box” of these mounts was lined up and drilled out incorrectly.

What would be stronger?

A box with a trapezoidal shape with panels resting on their edges, but held in with lots of bolts and angle...

Or...

Re-drilling new holes to make the box square, knowing you have old bolt holes within half an inch of the new ones?

Looking for advice.

Pics coming soon as these are close to completely installed.

Cheechako 03-01-2022 11:49

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Quote:

Originally Posted by Chotu (Post 3548542)
Structural question.

The “box” of these mounts was lined up and drilled out incorrectly.

What would be stronger?

A box with a trapezoidal shape with panels resting on their edges, but held in with lots of bolts and angle...

Or...

Re-drilling new holes to make the box square, knowing you have old bolt holes within half an inch of the new ones?

Looking for advice.

Pics coming soon as these are close to completely installed.

Can't really visualize what you are saying.
Even correctly drilled (?) a Trapezoid may have benefits though.

Chotu 03-01-2022 12:24

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Quote:

Originally Posted by Cheechako (Post 3548553)
Can't really visualize what you are saying.
Even correctly drilled (?) a Trapezoid may have benefits though.

I’ll snap a picture right now...

Chotu 05-01-2022 03:19

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
1 Attachment(s)
I got the mistake that happened sorted out by having them drill new holes and straighten things out. I guess that leaves me with some speed holes. Ha ha ha

Here is the nearly final product. These are a “forever solution since they are 100% composite. Made from a “polyester G10” They just need a little teak on the spot the outboards mount, so they have something to grip. Will keep looking for scrap teak. Marina dumpsters are usually full of it.

They are a bit heavier than the rotted wooden ones these replaced, but they will last longer than me, so I’m happy with that.


Another pic of them complete with outboards on them will be coming.

s/v Jedi 05-01-2022 21:45

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Quote:

Originally Posted by Chotu (Post 3549354)
I got the mistake that happened sorted out by having them drill new holes and straighten things out. I guess that leaves me with some speed holes. Ha ha ha

Here is the nearly final product. These are a “forever solution since they are 100% composite. Made from a “polyester G10” They just need a little teak on the spot the outboards mount, so they have something to grip. Will keep looking for scrap teak. Marina dumpsters are usually full of it.

They are a bit heavier than the rotted wooden ones these replaced, but they will last longer than me, so I’m happy with that.


Another pic of them complete with outboards on them will be coming.

Where you plan to use teak you can also use King Starboard to make it “forever”. Where did you source the fiberglass sheet? I made it myself last time and it was a pain.

Chotu 06-01-2022 01:11

Re: Pre Made Panels That Can Stand Up to Engines Pushing Them?
 
Quote:

Originally Posted by s/v Jedi (Post 3549752)
Where you plan to use teak you can also use King Starboard to make it “forever”. Where did you source the fiberglass sheet? I made it myself last time and it was a pain.

It may come to that. I’ll keep my eye out for dumpster teak for a bit still but if not, I may buy something like starboard.

Oh wow. Yeah. It would be difficult to make this type of 1/2” fiberglass sheet (and 1/4” fiberglass angle) for this sort of application. It would be a long job and can’t have the engineering precision of this stuff.

This stuff is called Extren 500 and I’ve used it extensively. See the davit above the engine mount in the pic? That’s square tube Extren 500 too. It’s come in VERY handy for all these little odds and ends. I even plan to use it for backing plates in some heavily loaded areas. Essentially, it’s nearly a direct replacement for aluminum, but it weighs a little less and lasts forever. It’s basically just a polyester G10. I love this product.

To source it, it’s best to work backwards. Go from the manufacturer’s website to find the local retailer. McMaster Carr sells it too.


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