MacGregorSailors.com

aft mast support arch

WILL I COMPROMISE STRENGTH IF I DRILL A HOLE IN IT??

I suspect Tom Foolery the engineer with the computer formulas would know this one - I was CONSIDERING drilling a 1/4 inch hole in the mast support arch on the bottom side to run a wire for a new wind sensor.

Am I going to make the arch fail if I do that?

Depends where in the arch you put the hole. Got a sketch?

in the horizontal part (the top) about midway between the center and the bend. should the hole be on the underside? or should it be on the back? I was avoiding the top so water can't get in.

remember the arch has 4 wholes where it is bolted to the boat. And even more there is the most stress... And the wholes go though both sides of the tube.

The whole that you will drill will just gon in 1 side of the tube.

I guess it will be no problem.

I was just looking to run the wire for a new wind sensor inside the tube. I just don't know if it would be better to drill the hole in the bottom or the front or rear sides - only one hole.

i assume most the pressure up there on the top of the arch is downward from the mast crutch - so I thought a stress crack from a hole would be most likely if the hole were drilled on the top - but really - i do not know. I thought maybe all you engineer guys might have a better knowledge of such things. that arch is a bendy metal, not a rigid cracking kind, right?

Front or back is better than top or bottom for the loads and the location. That’s assuming primarily vertical load from the mast weight.

Bending stresses are maximum in the top and bottom of the tube, and theoretically zero in the front and back. Shear stress in that spot is maximum, but small in magnitude, so not a concern. It’s why you drill holes in the middle third of a floor joist, and not near the top or bottom.

okay - i will pick a spot along the rear side - first i will look over some of the other arch pictures on the site and see where other people have drilled holes and see if they had any issues.

This may not be on the subject, but I wonder if you can drill holes into an arch with an impact driver?

Don't use your impact driver. Stainless steel actually hardens when it gets hot, and it has a very low heat conductivity, meaning heat won't spread easily. Your drill bit will get hot fast, and will get damaged.

You can actually drill fairly easily in stainless, even with standard HSS drill bits, but you have to take it SLOW. Use a drill that has a two speed setting, and variable speed trigger, put lots of pressure, and take it slow. Pause to let heat dissipate, and if you have oil, use some. You'll save you drill bits, and a lot of frustration that way!

Also, wear safety glasses!

pleb222 wrote: ↑Wed May 05, 2021 7:00 am Don't use your impact driver. Stainless steel actually hardens when it gets hot, and it has a very low heat conductivity, meaning heat won't spread easily. Your drill bit will get hot fast, and will get damaged.

You can actually drill fairly easily in stainless, even with standard HSS drill bits, but you have to take it SLOW. Use a drill that has a two speed setting, and variable speed trigger, put lots of pressure, and take it slow. Pause to let heat dissipate, and if you have oil, use some. You'll save you drill bits, and a lot of frustration that way!

Now you tell me.

I did burn up a bit or two drilling through SS tubes. Oil and pressure helped.

Question: My mast raising pole base is very bendy. Would applying heat make it stronger?

Can you clarify what you mean by "impact driver"?

Russ wrote: ↑Wed May 05, 2021 9:12 amQuestion: My mast raising pole base is very bendy. Would applying heat make it stronger?

You mean 'stiffer', and no, the Young's modulus* of aluminium doesn't change with heat treatment. It can be made stronger, meaning bending or tension/compression stresses can be higher without permanent damage (due to heat treating), but its stiffness won't change.

Aluminium is about 1/3 as stiff as steel (all grades), by the way, which is why when you see aluminium bicycle frames (for instance), the tubes are almost always larger than steel frames. Or thicker wall, but larger gets stiffer faster than thicker. If the frame design didn't take that into account, it would be wiggly beyond belief.

*a material property that represents stiffness within its elastic stress range, having nothing to do with the shape of the sample under consideration.

This may not be on the subject, but I wonder if you can drill holes into an arch with an impact driver? I am looking to buy one, but I am not sure if it is worth it. I found on powerdrillguru dot com a good impact driver, but I want to hear your opinion, guys, before making the purchase. So in case, someone had the experience of owning an impact driver tool, I would be grateful if you will share your thoughts about it. Thank you in advance. In case someone is willing to chat, feel free to text me. Wish you a good day, guys.

DoorsOfGuf wrote: ↑Wed May 05, 2021 11:42 pm This may not be on the subject, but I wonder if you can drill holes into an arch with an impact driver? I am looking to buy one, but I am not sure if it is worth it. I found on powerdrillguru dot com a good impact driver, but I want to hear your opinion, guys, before making the purchase. So in case, someone had the experience of owning an impact driver tool, I would be grateful if you will share your thoughts about it. Thank you in advance. In case someone is willing to chat, feel free to text me. Wish you a good day, guys.

No.

From the link you give:
"This nifty tool is made to do just one job – to drive screws. And it does it faster, better and easier than any other gadget. With an impact driver in 2020, you can drive any kind of fasteners, even the fat lag screws; that would stop even the best drill."

Not the right tool for drilling steel, or drilling anything really. If you want a versatile drill, you could get a hammer drill (NOT AN IMPACT DRIVER) that would allow you to drill masonry using the hammer feature, or wood/metal with the hammer feature turned off.

An impact driver is a great tool, though. If you ever have occasion to drive deck screws, lag bolts, or long wood screws, you will really enjoy it. It can also be used to assemble/disassemble small nut/bolt fasteners rapidly. I own one, and use it quite a bit.