need to install a cable gland

[paulga]

after you re-drill the pilot holes (for screws) into epoxy, do you fill the new holes with epoxy one more time, then fasten the screws before cure? this is my understanding from the marinehowto article

Just some sandpaper is good. Seal the edges with something if it is cored, a good idea even if not. If cored, the usual method is to dig out the core for 1/4 - 1/2" at the edge of the hole, then fill with thickened epoxy (West Six10 works well right out of the tube). On a large hole you can work various tools around to dig out the core, on a small hole one fairly easy way for soft cores is to chuck a small Allen key wrench in the drill, small enough that the short leg fits across the hole. Then starting slowly (because the drill will kick back initially), use the short leg of the Allen key to pulverize the core. The reason for this is that water can easily enter and migrate into the core if the wet seal fails, and wet core is a bad idea. Filling a donut around the hole with epoxy seals the edge.

 

[BruceK]

is epoxy available in small size tubes?
sealant in a tube has a very short shelf life once the seal is punctured. Buying west systems 105/205 for this job is overkill. I also do not expect a lot of glass projects within two years.

Sealant such as Sikaflex in the tubes around 300gm used in a frame "gun" keeps well in the freezer after opening, saving waste and giving sealant supply at hand. Use the onboard fridge freezer. Beats pricey little hard to squeeze soft tubes.

 

[paulga]

the cable seal accommodates 1.25" center hole, but for one ethernet cable, a 5/8" channel is enough for now.

is this straight flute drill what you refer to?

is the practice the same as a twist drill: start in reverse to score the gelcoat? then put in forward all the way through the wall? the other side which is also fiberglass will not be chipped, right?

The larger the hole saw or cutting diameter the slower the drill speed used. Assumption is within the same material. I like hole saws because they can be used on any material. Grit saws are slow, but easily controllable and load up quickly on soft materials like wood.
As mentioned, larger twist drill can bite into fiberglass and self feed there way in. I have a few straight flute drills (no twist) that work fantastic.

 

[Lou_tribal]

forstner bits are interesting. I initially thought it's a typo.

from previous posts, I remember the principle is to remove some core to create a pocket, and seal with thickened epoxy (un-thickened? west system 610 or?), redrill pilot holes without waiting for cure. For small screw holes, it’s easier just to overdrill the screw holes by 3/32 more than outside diameter of fasteners, fill with thickened epoxy, then redrill pilot holes (credit to Flatswing).

Do you mean the above bedding process should be followed if the installation is exposed to weather? now that the installation is in the sundeck, so there is no need to remove some peripheral core. Just adding a token amount of epoxy into the screw holes is sufficient for sealing. is my understanding correct?

Forstner bit are usually used to make a flat bottom hole in wood not a through hole.
If you use this, or any hole saw with pilot tip three recommendations:
1. Mark your center with a center punch tool so the pilot tip won't slip when you start.
2. To first scorch the surface, start in reverse. Teeth will just scorch the surface without bitting in making a cleaner start.
3. Don't drill through. As soon as the tip goes on the other side, stop, go to the other side, and use the small hole from the tip to guide the drill from the other side. Doing this you will get clean edges on both sides.

L

 

[Lou_tribal]

If you like hand work you can also try this:
https://www.renaissancewoodworker.com/center-bits/



L

 

[paulga]

i haven't done this before, but could see when the center bit is through, the hole saw would have already cut into the core.
I wondered if there is risk when you drill from the opposite side, the cutting circle does not match exactly the existing "cut circle" on the other end, as in the comic that two engineers collaborate on a railroad track, but only one of the two rails joined when they pulled together. The video in your previous post has cleared my question.

Forstner bit are usually used to make a flat bottom hole in wood not a through hole.
If you use this, or any hole saw with pilot tip three recommendations:
1. Mark your center with a center punch tool so the pilot tip won't slip when you start.
2. To first scorch the surface, start in reverse. Teeth will just scorch the surface without bitting in making a cleaner start.
3. Don't drill through. As soon as the tip goes on the other side, stop, go to the other side, and use the small hole from the tip to guide the drill from the other side. Doing this you will get clean edges on both sides.

L

 

[Lou_tribal]

i haven't done this before, but could see when the center bit is through, the hole saw would have already cut into the core.
is there risk when you drill from the opposite side, the cutting circle does not match exactly the existing "cut circle" on the other end? the comic that two engineers collaborate on a railroad track, but only one of the two rails joined when they pulled together

As you will use the center hole to guide you the deviation will be minimal.

L

 

[Comodave]

If you are going to drill a 1.25” hole I would only use a hole saw. Forstner bits will need a guide to keep it centered in one spot or it will drift unless you are using some kind of drill press, unlikely. The hole saw will have a 1/4” pilot bit. Drill forward until the pilot bit has gone into the glass then reverse the drill and cut through the gel coat. Then go forward and cut through the glass. You can then use the pilot hole from the inside to repeat this process. Seal up the core as said above. Then position the gland and mark the 3 small holes. Drill the correct size, very important, for the self tapping or sheet metal screws. Then use a countersink to bevel the holes out past the screw threads so you don’t chip or lift the gel coat. Then you can use some unthickened epoxy in the holes. Redrill the holes after the epoxy has gone off with the proper size drill bit. Not too big a bit and certainly not to small or the screws will break off. Then use some Sika 291 in the screw holes and under the gland after wiping with acetone to remove any contaminants from the surface so the caulk will stick. The countersink will allow some caulk around the screws like an O ring to help seal it. I prefer caulk over butyl when using screws and not bolts. It is difficult to get proper squeeze out with screws. But when bolting I definitely use butyl tape since the bolts can be progressively tightened to squeeze out the butyl properly.

 

[TJM]

Your post #33 shows a Reamer, this is a very different tool. This tool is used to increase the size of a previously drilled hole.
Using a straight fluted drill eliminates the "pulling" issue with a twist drill in certain materials. It will not eliminate the chipping of the gelcoat.

I fear that you are getting a lot of great responses and tips and not understanding that each tip may only work with a certain process.
No disrespect meant, but DIY projects are not ala cart.

 

[paulga]

Thanks for reiterating the steps.
The screws are self tapping
When you redrill the epoxy, do you use a drill bit the same size of or a bit smaller than the diameter of the screw's top thread?

If you are going to drill a 1.25” hole I would only use a hole saw. Forstner bits will need a guide to keep it centered in one spot or it will drift unless you are using some kind of drill press, unlikely. The hole saw will have a 1/4” pilot bit. Drill forward until the pilot bit has gone into the glass then reverse the drill and cut through the gel coat. Then go forward and cut through the glass. You can then use the pilot hole from the inside to repeat this process. Seal up the core as said above. Then position the gland and mark the 3 small holes. Drill the correct size, very important, for the self tapping or sheet metal screws. Then use a countersink to bevel the holes out past the screw threads so you don’t chip or lift the gel coat. Then you can use some unthickened epoxy in the holes. Redrill the holes after the epoxy has gone off with the proper size drill bit. Not too big a bit and certainly not to small or the screws will break off. Then use some Sika 291 in the screw holes and under the gland after wiping with acetone to remove any contaminants from the surface so the caulk will stick. The countersink will allow some caulk around the screws like an O ring to help seal it. I prefer caulk over butyl when using screws and not bolts. It is difficult to get proper squeeze out with screws. But when bolting I definitely use butyl tape since the bolts can be progressively tightened to squeeze out the butyl properly.

 

[Comodave]

You drill a hole that is the diameter of the screws shank. If the hole is smaller than the shank you will likely break the screw since the fiberglass is much stronger than wood.

 

[paulga]

Thanks.
A machine screw has no shank, how large of a redrill hole in the epoxy do you make for a machine screw?

You drill a hole that
is the diameter of the screws shank. If the hole is smaller than the shank you will likely break the screw since the fiberglass is much stronger than wood.

 

[Bmarler]

Thanks.
A machine screw has no shank, how large of a redrill hole in the epoxy do you make for a machine screw?

Depends on whether or not you are planning on tapping the hole or using a nut and washer. Epoxy will be strong enough to tap for machine screws if the load isn’t too high. Otherwise, if you plane for a nut and washer, just drill nominal size for starters. For example, I prefer a 1/4 hole for a 1/4 screw. You can always enlarge a little if you’re off a bit.

 

[Comodave]

I assumed you were going to use a sheet metal screw to attach the gland. If you are going to use a machine screw then you can tap the epoxy or through bolt it.

 

[paulga]

I assumed you were going to use a sheet metal screw to attach the gland. If you are going to use a machine screw then you can tap the epoxy or through bolt it.

the manual says the screws are 634SMS316
I don't know how to decode it
you can see it in the photo, it has threads all the way to underneath the head. does this make it a sheet metal rather than a self tapping screw?

now that there is no shank, how do you select bit size for re drill?

 

[paulga]

sure, something like this maybe? https://www.amazon.com/dp/B08DZH7V9...p_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM

how do you mix it then brush it?

a youtube video says to mix 3 minutes in container1 then transfer to container2 to mix with a new stick for 3 more minutes, keeping the temp around 70F.

this installation will need less than 1oz. so the above method does not sound like right.

 

[Comodave]

the manual says the screws are 634SMS316
I don't know how to decode it
you can see it in the photo, it has threads all the way to underneath the head. does this make it a sheet metal rather than a self tapping screw?

now that there is no shank, how do you select bit size for re drill?

View attachment 144819

View attachment 144818

That looks like a sheet metal screw. Being a new owner of a boat that needs work I would suggest that you go to a hardware store and look at different hardware and see what it is called, it will make your life much easier. The shank of the screw is there even though it has threads all the way, it is the diameter of the body of the screws without the threads.

 

[Comodave]

how do you mix it then brush it?

a youtube video says to mix 3 minutes in container1 then transfer to container2 to mix with a new stick for 3 more minutes, keeping the temp around 70F.

this installation will need less than 1oz. so the above method does not sound like right.

You might buy some epoxy from West Systems or Total Boat. Then read the directions and learn to use the epoxy because you will be using it for you whole boating life. I like West because they have excellent support and have a lot of how to info online and in pamphlets.

 

[TJM]

Boaters either need to have a lot of money (for the Marina to do their work) or be a very skilled DIY'r. You will need to learn and understand thread geometry. People use different terminology for threads across the world.
Example: Nominal thread size = Major diameter = clearance diameter.
Minor diameter = shank size. I never heard that term used before but I knew what Dave meant.
Sheet metal screw is NOT a machine screw.
They make machine screws that might be called "self tapping", because they form the thread without chips.
Sheet metal screw is very similar to a wood screw and very similar to a self tapping screw.
Stainless Steel screws are soft and the small ones will shear right off inside fiberglass, OUCH.
Thru bolting is MUCH stronger than threading into fiberglass, but may not always be possible. I personally would never thread fiberglass with a machine screw. The thread pitch is too shallow, use a sheet metal screw that has a deeper bite.

As far as understanding what this means? 634SMS316. This means nothing except to the manufacturer. This is a part number and NOT a thread size or callout. It might be a number 6 screw out of 316 stainless alloy, but we do not know by this number.

 

[Bmarler]

Maybe get yourself a screw checking gauge. There are many versions of these, but this one seems pretty nice.: https://www.amazon.com/Screw-Chekr-Thread-Gauge-Checker/dp/B0006NFUJW?th=1

 

[paulga]

Thanks for confirming self-tapping and sheet metal screws have similar requirement on the hole size. metal screws requires a larger.

That looks like a sheet metal screw. Being a new owner of a boat that needs work I would suggest that you go to a hardware store and look at different hardware and see what it is called, it will make your life much easier. The shank of the screw is there even though it has threads all the way, it is the diameter of the body of the screws without the threads.

 

[paulga]

You might buy some epoxy from West Systems or Total Boat. Then read the directions and learn to use the epoxy because you will be using it for you whole boating life. I like West because they have excellent support and have a lot of how to info online and in pamphlets.

mix with the measure cup and stick?
use a syringe to inject the epoxy to screw holes?
use a brush to paint inside the center hole?

is the brush and syringe generally for one-time use?

 

[Comodave]

The epoxies from West have a 1:1 mix ratio. You can get a set of pumps so you just do one pump from the resin and one pump of the hardner. Then mix with a stirring stick. West sells syringes made for epoxy. They can be cleaned with acetone after use so they can be used multiple times. Depending on the application I sometimes use a syringe and sometimes just slarher it on.

 

[paulga]

If you redrill for a machine screw (to be used with a nut and washer), do you fill un-thickened epoxy in it or still use sikaflex?

If you are going to drill a 1.25” hole I would only use a hole saw. Forstner bits will need a guide to keep it centered in one spot or it will drift unless you are using some kind of drill press, unlikely. The hole saw will have a 1/4” pilot bit. Drill forward until the pilot bit has gone into the glass then reverse the drill and cut through the gel coat. Then go forward and cut through the glass. You can then use the pilot hole from the inside to repeat this process. Seal up the core as said above. Then position the gland and mark the 3 small holes. Drill the correct size, very important, for the self tapping or sheet metal screws. Then use a countersink to bevel the holes out past the screw threads so you don’t chip or lift the gel coat. Then you can use some unthickened epoxy in the holes. Redrill the holes after the epoxy has gone off with the proper size drill bit. Not too big a bit and certainly not to small or the screws will break off. Then use some Sika 291 in the screw holes and under the gland after wiping with acetone to remove any contaminants from the surface so the caulk will stick. The countersink will allow some caulk around the screws like an O ring to help seal it. I prefer caulk over butyl when using screws and not bolts. It is difficult to get proper squeeze out with screws. But when bolting I definitely use butyl tape since the bolts can be progressively tightened to squeeze out the butyl properly.

 

[paulga]

The epoxies from West have a 1:1 mix ratio. You can get a set of pumps so you just do one pump from the resin and one pump of the hardner. Then mix with a stirring stick. West sells syringes made for epoxy. They can be cleaned with acetone after use so they can be used multiple times. Depending on the application I sometimes use a syringe and sometimes just slarher it on.

is the 1:1 ratio very strict? the article on marinehowto also says to mix in Cabosil later, then remove trapped air bubbles. it makes the process too complex. Can west system Six10 be used instead of unthickened epoxy?

 

[Comodave]

is the 1:1 ratio very strict? the article on marinehowto also says to mix in Cabosil later, then remove trapped air bubbles. it makes the process too complex. Can west system Six10 be used instead of unthickened epoxy?

The ratio is very strict as to resin and hardner. You can add things like milled fiberglass, cabosil and various other thickners. Thickners are not part of the ratio. You add as much thickner as you need to make the epoxy the viscosity you want. Six10 is thickened epoxy. It mixes in the tube to save the step og adding thickner. It is for a different application than unthickened epoxy. It works fine but is more expensive and you don’t have a choice of what viscosity you want. I use it occasionally but normally just mix my own thickner into the epoxy so I get exactly what I want. I have probably 5 or so different thickners to choose from. Although mostly I use 404, I believe, which is for structural work.

 

[jbinbi]

I use these sometimes for the screw holes. Drill and countersink in one operation.
https://www.amazon.com/FTG-Maximum-...HzsLXOpAx-ob5oAz9X2O7PLUbKhoCSLYQAvD_BwE&th=1

This for the win. This is what I do as well. For the enet cable, you don't need a hole saw. Also, you want the hole for the rubber grommet to be a tight fit, use some lubiricant to pass it through. It will compress more when you tighten the outside shell.

 

[paulga]

the biggest bit in that set is #12 or 7/32", do you mean that is enough to pass the ethernet cable through?

I'm thinking to drill a 7/8" hole (it can be up to 1.25"). using a crimper to make ethernet connector is a new skill but I'd like to leave it for future.

This for the win. This is what I do as well. For the enet cable, you don't need a hole saw. Also, you want the hole for the rubber grommet to be a tight fit, use some lubiricant to pass it through. It will compress more when you tighten the outside shell.

 

[Philkoury]

The epoxies from West have a 1:1 mix ratio. You can get a set of pumps so you just do one pump from the resin and one pump of the hardner. Then mix with a stirring stick. West sells syringes made for epoxy. They can be cleaned with acetone after use so they can be used multiple times. Depending on the application I sometimes use a syringe and sometimes just slarher it on.

West system epoxy does not have a 1:1 mix ratio.

From West Systems web site>

Using the pump
Pump one full pump stroke of resin for each one full pump stroke of hardener. Depress each pump head fully and allow the head to come completely back to the top before beginning the next stroke. Partial strokes will give the wrong ratio. Read the pump instructions before using the pumps.

Mixing by volume or weight
To measure 105 Resin and 205 or 206 Hardener by weight or volume, combine 5 parts resin with 1 part hardener. To measure 105 Resin with 207 or 209 Hardener by volume, combine 3 parts resin with 1 part hardener ( by weight, combine 3.5 parts of resin with 1 part of hardener).

 

[paulga]

Thanks for pointing this out to me.
the youtube video how to use the west system mini pumps explains it clearly

West system epoxy does not have a 1:1 mix ratio.

From West Systems web site>

Using the pump
Pump one full pump stroke of resin for each one full pump stroke of hardener. Depress each pump head fully and allow the head to come completely back to the top before beginning the next stroke. Partial strokes will give the wrong ratio. Read the pump instructions before using the pumps.

Mixing by volume or weight
To measure 105 Resin and 205 or 206 Hardener by weight or volume, combine 5 parts resin with 1 part hardener. To measure 105 Resin with 207 or 209 Hardener by volume, combine 3 parts resin with 1 part hardener ( by weight, combine 3.5 parts of resin with 1 part of hardener).