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Drilling and tapping holes in the frame
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=67415		 Page 1 of 1
Author:  dunebugmi [ Mon Sep 21, 2020 7:58 am ]
Post subject:  Drilling and tapping holes in the frame
Does anyone have experience drilling and tapping the frame / cross-beam, or thoughts on how to do it and what to avoid?

I have the older 80's style jib cleat system that is difficult to do single-handed. I've been working on upgrading it to something I can man myself. I bought a couple of swivel cam cleats and would like to install them onto the crossbeam.

Is there a cross section out there for the cross beam? I found this for the mast: https://www.hobie.com/forums/viewtopic.php?f=9&t=58017.

Is the frame filled with foam or anything like that?

Should I add a sealant to my screws to try to keep it leak-tight?

I purchased the part below, and It has one #10 screwhole and two #8 screwholes. I'm thinking about drilling the #8s out to a #10 size so that I can use three of the same screw type.

https://www.ebay.com/itm/Hobie-Swivel-C ... 2749.l2649

Thanks!
Author:  flatlander [ Mon Sep 21, 2020 9:31 am ]
Post subject:  Re: Drilling and tapping holes in the frame
The crossbars and side rails are a hollow extrusion, similar to the mast.

Drill and tap at will, with no need for sealing

Cheers!
Author:  Tim H16 [ Mon Sep 21, 2020 9:53 am ]
Post subject:  Re: Drilling and tapping holes in the frame
If you are drilling through the front cross beam for something like a new mast step, try not to drill through the "luff/tramp track" part since it will make it harder to pull a rivet properly or it will make it harder to insert the rope encased edge of a tramp through the "luff/tramp track" part of the side rails, front or rear cross beams.

Also SS rivets are better than screws.

The Hobie Part Catalog has the proper size and type of SS rivets you should use listed in a table on page 2 of 4 for your boat.
Author:  dunebugmi [ Tue Sep 22, 2020 5:27 am ]
Post subject:  Re: Drilling and tapping holes in the frame
Tim H16 wrote:
Also SS rivets are better than screws.


I have been considering rivets, but the part was constructed with countersinks. I think the (stainless) flathead screw would be stronger on the plastic side, but weaker inside the frame. A rivet, it seems to me, would be stronger on the frame side, but weaker on the part side due to the missing material underneath the rivet flange.

If I'm thinking about it correctly, I can drill the tapped hole out to rivet size, but cannot do the reverse. Wish I knew the thickness of the aluminum crossbeam.

Thanks for the tip about the catalog page!
Author:  Tim H16 [ Tue Sep 22, 2020 6:49 am ]
Post subject:  Re: Drilling and tapping holes in the frame
You can always use the SS countersunk rivets, the same type used on the jib and main sail traveler tracks. They are pretty strong.
Author:  srm [ Tue Sep 22, 2020 10:37 am ]
Post subject:  Re: Drilling and tapping holes in the frame
The crossbar wall thickness is around 0.100” give or take. I haven’t looked at a 16 cross beam closely, but some of the beams and extrusions that I have looked at actually have varying thickness with some extra material added to the very sides (on the inside). Anyway, there is enough thickness there to drill and tap, but you have to be careful not to over-tighten or you could pretty easily strip the threads. You could always look into using rivnuts, which would essentially give you the best of both worlds.

For the part you’re looking to install, I believe the stock installation method is to use a rivet (countersunk) for the back hole. Then use two stainless steel flat head sheet metal screws (not machine scresws) for the two fasteners that pass through the base of the cleat and through the plastic mounting bracket.

sm
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