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Old 09-04-2016, 21:16   #16
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Re: Novel idea for fabricating backing plates

Like you, Greg (Stumble), I also thought since G10 is so hard there's a chance a diamond blade could do well, but did not consider the heat-generating aspect of that approach.

Thanks Minaret for your informative reply, including the issue of feed rate.
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Old 09-04-2016, 23:08   #17
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Re: Novel idea for fabricating backing plates

I really do love the wealth of experience here.
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Old 10-04-2016, 10:46   #18
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Re: Novel idea for fabricating backing plates

Diamond "crusted" hole saws are actually fairly cheap (industrial diamond grit isn't as costly as gemstones(G) and they are standard in masonry and tile shops for cutting holes in granite kitchen counters and other stone materials. So G10 shouldn't slow them down any.


But the best cutting tool might be a waterjet. And since so few of us will have one of those, that might mean a stop at a local machine shop, where a waterjet could be found and the charge to do a small job on customer-supplied odd stock (G10) shouldn't be much, considering everything else.
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Old 10-04-2016, 11:46   #19
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Re: Novel idea for fabricating backing plates

HelloSailor.

You may be right, but just like I don't have a water jet to cut stainless backing plates I won't have one to cut G-10. I do find G10 to be far easier to work with than stainless however. Any standard jigsaw with a carbide hit works fine. Maybe not as well as a water jet, but still.

Now if I owned a water jet or had free access to one... I would still probably cut backing plates at the dock with a jig saw. It's just easier.
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Old 10-04-2016, 14:26   #20
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Re: Novel idea for fabricating backing plates

Reasonably good backing plates can be cut from plastic kitchen carving boards.

Non rotting, easy machining and cheap.

I used a hole saw to make smaller ones...

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Old 10-04-2016, 14:38   #21
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Re: Novel idea for fabricating backing plates

Quote:
Originally Posted by Franziska View Post
Reasonably good backing plates can be cut from plastic kitchen carving boards.

Non rotting, easy machining and cheap.

I used a hole saw to make smaller ones...

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Carving boards also have zero structural strength. The compression of the bolts alone will cause the plastic to cold flow away from the fastners. It really isn't sutable.
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Old 10-04-2016, 14:50   #22
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Re: Novel idea for fabricating backing plates

Quote:
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Use carbide abrasive saw blades for cutting glass.
The Carbide abrasive type jigsaw blades don't work on G10. the bits of carbide just come off. you're better to use a fine toothed metal jigsaw blade. they cut through it quickly.
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Old 10-04-2016, 15:15   #23
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Re: Novel idea for fabricating backing plates

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The Carbide abrasive type jigsaw blades don't work on G10. the bits of carbide just come off. you're better to use a fine toothed metal jigsaw blade. they cut through it quickly.


I've cut a whole crapload of G10 with carbide abrasive blades, for jig saws, circ saws, band saws, table saws, etc etc. Never once seen that happen. Carbide abrasives are by far the best tool for the job. Got some 1/2" G10 I have to saw up later this week, will post video. I even use broken carbide abrasive band saw blades to braze onto dull Fein saw blades for cutting glass. Works amazingly well. Much cheaper than their abrasive blades, and more aggressive. Carbide doesn't leave a rough edge with burn marks like a toothed saw does, either.
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Old 10-04-2016, 15:18   #24
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Re: Novel idea for fabricating backing plates

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Originally Posted by minaret View Post
I've cut a whole crapload of G10 with carbide abrasive blades, for jig saws, circ saws, band saws, table saws, etc etc. Never once seen that happen. Carbide abrasives are by far the best tool for the job. Got some 1/2" G10 I have to saw up later this week, will post video. I even use broken carbide abrasive band saw blades to braze onto dull Fein saw blades for cutting glass. Works amazingly well. Much cheaper than their abrasive blades, and more aggressive.
I've never had any luck with the abrasive blades. I've made 10 backing blocks for my thruhulls and the couple of abrasive blades I tried didn't even survive long enough to cut 1 5inch circle. switched back to regular fine metal cutting blades and 1 lasted most of the rest. maybe I just happened to get a bad batch of blades.
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Old 10-04-2016, 15:19   #25
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Re: Novel idea for fabricating backing plates

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I've never had any luck with the abrasive blades. I've made 10 backing blocks for my thruhulls and the couple of abrasive blades I tried didn't even survive long enough to cut 1 5inch circle. switched back to regular fine metal cutting blades and 1 lasted most of the rest. maybe I just happened to get a bad batch of blades.


What brand? Certainly wasn't Lenox. I have Lenox carbide abrasive hole saws that have cut dozens of holes through very thick hulls and are still "sharp". Very pricey though.
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Old 10-04-2016, 15:23   #26
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Re: Novel idea for fabricating backing plates

@Stumble

Well, depends probably what size and precise plastic.
Mine lasted fine for several years, and we're still fine when I sold the boat.
They where not foamed up.Rather polyethylene/nylon style plastic.
Used large washers underneath.

Obviously they need a certain diameter.
The only mayor load they had was compression.

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Old 10-04-2016, 17:44   #27
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Re: Novel idea for fabricating backing plates

Quote:
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@Stumble

Well, depends probably what size and precise plastic.
Mine lasted fine for several years, and we're still fine when I sold the boat.
They where not foamed up.Rather polyethylene/nylon style plastic.
Used large washers underneath.

Obviously they need a certain diameter.
The only mayor load they had was compression.

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Admittedly the type of plastic matters, but almost all plastic cutting board are made from HDPE plastic. You almost couldn't design a worse material for backing plates for heavily loaded hardware.

- It's coefficient of thermal expansion is so high that you have to use spring washers to retain appropriate torque on the bolt.
- it will cold form under normal preassures found in typical bolt assemblies, so you need to constantly retorque the nuts

HDPE simply isn't dimensionally stable enough to spread the load of deck hardware. It may appear to work for some period of time, but it will eventually fail. G10 however is almost custom designed as backing plate material. And it isn't like its hard to find or terribly expensive.
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