Crack in er hatch beam

[paulga]

Unless you are on a lake, use stainless. And don't overthink this. There's a big dent in the wood above the crack. Something whacked it and split the wood. Either replace it or glue, epoxy/ bolt it together and forget about it. BTW, you're engine and room are crazy clean and shiny!

Thanks. Single screw allows more room for moving around.

 

[paulga]

Where the crack ends consider drilling a 3/32" or 1/8" hole at the end of the crack. Many times this will prevent a crack from going further. The challenge is trying to match the angle of the crack such as drilling straight in or at an up or down angle.

How does the hole stop the crack?

 

[paulga]

West epoxy has a slow and fast hardner available. The fast is good down to 40 degrees per West. However I have used it at 20 degrees and it worked fine.

I have total boat resin and hardener, it is similar to the west system product except a different volume ratio required.

Do you use thickened or unthickened epoxy for this?

 

[SoWhat]

The crossbeams are removable. They support the deck sections (aka hatches). It is possible the crack appeared when someone dropped the hatch from vertical position. The weight of the hatch is spread out along 4 edges so the crack is not critical but should be repaired. Put it on your spring launch list.

Any waterproof wood glue would work along with a few #10 St Stl phillip hd wood screws in countersunk holes, couple in both top and bottom. I might pry open crack a bit with fingers to allow glue penetration. I would not insert anything into crack as it might end up cracking the whole crossbeam. If so the repair would remain the same. I think epoxy would be too thick to flow into microscopic crack. glue is a better choice.

Don't drop the hatches.

 

[Comodave]

It depends on the width of the crack. If there is a gap then you can use thickened epoxy. If there isn’t any gap then use unthickened epoxy.

 

[paulga]

The crossbeams are removable. They support the deck sections (aka hatches). It is possible the crack appeared when someone dropped the hatch from vertical position. The weight of the hatch is spread out along 4 edges so the crack is not critical but should be repaired. Put it on your spring launch list.

Any waterproof wood glue would work along with a few #10 St Stl phillip hd wood screws in countersunk holes, couple in both top and bottom. I might pry open crack a bit with fingers to allow glue penetration. I would not insert anything into crack as it might end up cracking the whole crossbeam. If so the repair would remain the same. I think epoxy would be too thick to flow into microscopic crack. glue is a better choice.

Don't drop the hatches.

Two screws from top, two from bottom, forming a cross patten?

The beam thickness is about 2", so #10 7/8" screws should be good?

I planned to install just one 1/4" x 2 1/2" flat head machine screws, with a 1/4 x 1 1/4 fender washer and a 1/4 nyloc nut from bottom. Does this achieve the same as using multiple wood screws?

 

[mike66]

It should but it leaves something sticking out on the bottom. And I'd probably scratch my head or snag on it going down below.

 

[SoWhat]

Two screws from top, two from bottom, forming a cross patten?

The beam thickness is about 2", so #10 7/8" screws should be good?

I planned to install just one 1/4" x 2 1/2" flat head machine screws, with a 1/4 x 1 1/4 fender washer and a 1/4 nyloc nut from bottom. Does this achieve the same as using multiple wood screws?

I would use more than one, but you may gouge your head on the nuts when moving around ER.

 

[RT Firefly]

Greetings,
Ms. P. People are making this repair WAY too complicated. Mr. SW explained it VERY well and simply. Drill and countersink, put glue in the crack, clamp and put in 2 screws Since the beam is 2", you're fine in using 1 1/2" screws (don't countersink too much).
I would clamp after putting in glue and before installing screws.
Absolutely NO need for nuts and bolts IMO.

 

[paulga]

Greetings,
Ms. P. People are making this repair WAY too complicated. Mr. SW explained it VERY well and simply. Drill and countersink, put glue in the crack, clamp and put in 2 screws Since the beam is 2", you're fine in using 1 1/2" screws (don't countersink too much).
I would clamp after putting in glue and before installing screws.
Absolutely NO need for nuts and bolts IMO.

is this the correct flow:
1. fill glue,
2. wait for a day,
3. clamp and drill two pilot holes, install screws

in step 3, is countersink really necessary? where exactly would you place the two holes?

 

[RT Firefly]

Ms. P
Nope do everything at once in this order: Drill & countersink. Glue. Clamp. Put in screws. One step right after the other. No rush but don't wait hours. Don't remove clamps until glue sets up-probably a day is OK.

Yes. Countersink or the screw head will be protruding. Use flat head SS screws. My opinion is #8's X 1 1/2" should be sufficient. You can always go larger size (or nuts and bolts) in the future if necessary, going smaller is a PIA. There is a "formula" somewhere? that will suggest best size drill bit for drilling in hard wood. I'm guessing 9/16" for #8's. Drive them in snug but don't don't over tighten or they will strip out. IF you do happen to strip one out, proceed and fix it after the fact.

No problem if you put 2 screws in from either side-4 screws total (again IMO). 2 on either side 1" down from the "step" and 1/2" from the edges. IF you're going from both sides space them so they don't run into each other.

When you're pre-drilling (again 9/16"?????) don't be afraid to drill completely through the beam. Too long a hole is preferable to too short. Too short and you risk cracking the wood or breaking the screw off.

 

[paulga]

Ms. P
Nope do everything at once in this order: Drill & countersink. Glue. Clamp. Put in screws. One step right after the other. No rush but don't wait hours. Don't remove clamps until glue sets up-probably a day is OK.

Yes. Countersink or the screw head will be protruding. Use flat head SS screws. My opinion is #8's X 1 1/2" should be sufficient. You can always go larger size (or nuts and bolts) in the future if necessary, going smaller is a PIA. There is a "formula" somewhere? that will suggest best size drill bit for drilling in hard wood. I'm guessing 9/16" for #8's. Drive them in snug but don't don't over tighten or they will strip out. IF you do happen to strip one out, proceed and fix it after the fact.

No problem if you put 2 screws in from either side-4 screws total (again IMO). 2 on either side 1" down from the "step" and 1/2" from the edges. IF you're going from both sides space them so they don't run into each other.

When you're pre-drilling (again 9/16"?????) don't be afraid to drill completely through the beam. Too long a hole is preferable to too short. Too short and you risk cracking the wood or breaking the screw off.

i just measured the beam again, its thickness is 2-1/4"
which works better? #8 x1-3/4" flat head screws or #8 x 2"

here is a pilot hole size guideline for wood screws i found online. the beam should be hard wood, so I'd use a 1/8 straight bit

 

[luna]

9/16" is larger than 1/2", the entire screw including the head would simply fall through the hole.

If you are going to use a #8 screw and it's a hardwood drill a 1/8" diameter hole. The depth of the hole should be about 1/8" shorter than the screw length. The point will make its own hole.

If you use a few #10 screws, there you need to drill a 9/64" diameter hole.

If you consider it a softwood, take 1/64" off of the above drill sizes.

Rule of thumb, drill ever so slightly smaller than the screws root diameter.

I would through bolt it using #10 machine screws as they are stronger.

 

[RT Firefly]

Greetings,
Mr. L. Brain fart. 9/64”. Drat the Imperial system.

 

[paulga]

9/16" is larger than 1/2", the entire screw including the head would simply fall through the hole.

If you are going to use a #8 screw and it's a hardwood drill a 1/8" diameter hole. The depth of the hole should be about 1/8" shorter than the screw length. The point will make its own hole.

If you use a few #10 screws, there you need to drill a 9/64" diameter hole.

If you consider it a softwood, take 1/64" off of the above drill sizes.

Rule of thumb, drill ever so slightly smaller than the screws root diameter.

I would through bolt it using #10 machine screws as they are stronger.

is there a pilot hole / countersink size chart for machine screws? i remember the pilot hole size should be nominal diameter, so that is 3/16" for #10 and 1/4" for a 1/4" (#14) machine screw?

 

[RT Firefly]

Greetings,
Ms. P. I usually counter sink to VERY slightly larger than the head of the screw.

 

[paulga]

Greetings,
Ms. P. I usually counter sink to VERY slightly larger than the head of the screw.

I have a countersink bit from the bosch kit but it does not have size marking. does this work or should I use specific size countersink bit?

 

[RT Firefly]

Greetings,
Ms P. Really simple. Countersink using that bit and every so often try to put the screw head upside down into the hole. When it's right, the edge of the screw head will be pretty well even with edge of the counter sink depression.
There ARE different angle countersinks but for what you're doing it won't matter. That one will work fine.
You don't have to overthink this. If you make a mistake you can do it again.

 

[luna]

I've never had any luck having a #10 machine screw drop-in tight into a 3/16" diameter hole as the machine screw is 0.190" and the hole is 0.188". You can force it into your 2 1/4"+/- thick wood beam but you will have to twist it out. That is why I use a #11 (0.191") or depending on the wood a #10 (0.193") drill bit. Yes, they make drill bits in Number and Letter sizes (google it) for when you want to get things right.

WRT your Bosch countersink, as long as it cuts the wood at a 82º angle (Note, metric fasteners typically use a 90º included angle, go figure!) and is at least 7/16" in diameter, it should provide you with a deep enough countersink to have the top of the machine screw sit flush or slightly below the top of the wood.

 

[RedRascal]

How does the hole stop the crack?

It helps terminate the crack at the hole. Before the hole is cracked wood, after the hole is wood without a crack and stronger. You can experiment with the technique on a scrap piece of wood where you create a crack or split then drill a hole at the end of it. Then see if you think it takes more effort than before to make the crack grow.

 

[paulga]

I'm going to install one machine screw and some wood screws

I got 1/4" -20 x 2.5" machine screw, is it sufficient or a bit short?

 

[RT Firefly]

Greetings,
Ms. p. Just fine. Use an acorn nut with a washer. If you use a regular nut you're more apt to snag something on it or cut yourself on the open threads.

 

[rslifkin]

It looks long enough to get a nut and washer on it. So it's long enough.

 

[RedRascal]

I would vote for a pan or truss head bolt. The flat head screw with the taper that you show can act as a wedge and create cracks if it is over tightened. Keeping the screw a few inches away from the end of the beam would be wise and probably safe. Placing the screw a 1/2" from the end would probably spell more trouble.

 

[paulga]

I would vote for a pan or truss head bolt. The flat head screw with the taper that you show can act as a wedge and create cracks if it is over tightened. Keeping the screw a few inches away from the end of the beam would be wise and probably safe. Placing the screw a 1/2" from the end would probably spell more trouble.

flat head is more intuitive to fit the countersink hole. using a pan head bolt, can you still use the same countershink bit to make the head flush with the surface?

 

[RedRascal]

The correct bit would be a Brad Point Bit. However you could use a regular drill bit and then flatten out the countersunk hole with a small 1/4" chisel. A countersunk bit will create more taper and require more chisel work to get it flat. It would probably only take a minute or two of chisel work to flatten it out with either bit though.

 

[paulga]

The correct bit would be a Brad Point Bit. However you could use a regular drill bit and then flatten out the countersunk hole with a small 1/4" chisel. A countersunk bit will create more taper and require more chisel work to get it flat. It would probably only take a minute or two of chisel work to flatten it out with either bit though.

I see, brad point bit create a non tapered recess to fit the screw head. Do you have to first use the brad point bit to make the recess, then change to a regular drill bit for the pilot hole?

 

[RedRascal]

Do you have to first use the brad point bit to make the recess, then change to a regular drill bit for the pilot hole?

Yep. If you do this with a sharp new bit just be cautious about not letting it drill too deep. Sometimes a sharp bit will cut really well and your intended 1/4" recess becomes a 1/2" recess in about a half of a second.

 

[paulga]

I see, brad point bit create a non tapered recess to fit the screw head. Do you have to first use the brad point bit to make the recess, then change to a regular drill bit for the pilot hole?

how do you use a small chisel and a hammer? to create the same recess?

 

[RT Firefly]

Greetings,
I have used a "drill stop" (home made) to prevent a drill bit from running in too far. A piece of dowel with your selected bit run through the center of it and cut so one end of the dowel sits against the chuck teeth with the appropriate length of drill protruding from the other (dowel is cut to length to allow desired depth of hole to protrude).