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What wall thickness tubing for leaning post?

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What wall thickness tubing for leaning post?

Old 11-26-2016, 09:34 PM
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Default What wall thickness tubing for leaning post?

My winter project is building a small leaning post for a 17 foot CC. It is going to be a fairly simple design, similar to this:



I am a novice at best at metal fabrication. What size wall thickness should I get? I am going to use 1"-1.25" OD Aluminum tubing. I just don't know how thick of a wall I need.

Also, beyond the structural aspect of it, I will be MIG welding this and I understand you generally need thicker material to MIG weld something (vs TIG) without blowing a bunch of holes in it.

I was thinking .125 wall (1/8th inch) but I would like to hear from someone that knows if that is a good idea.
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Old 11-26-2016, 09:40 PM
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I think you need to go a little thicker like 3/16.

I started welding this year, I'm more of a grinder than a welder at this point but to make it look nice you really need to TiG it.

Check out this one. By the time you try to get everything and have it upholstered this may be a cheaper option.
http://www.marineproducts.net/32-mini-rocket-launcher/
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Old 11-26-2016, 10:30 PM
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I would also agree this should be tig weled it will look a lot better and much stronger
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Old 11-26-2016, 10:31 PM
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I saw that one. It is too wide IMO for this boat. The boats claims to be a 17 footer but it feels more like a 16 to me. I have never pulled a tape on it though. It has a flip flop seat right now which is 26" wide and I don't want to go any wider than that.

Part of the reason I am doing this is to have something to do in the evenings. I'd like to have something that works at the end of the day but looks aren't everything. This is going on a boat worth less than 4k. It looks like 1/4 wall tube is as cheap or cheaper than the thinner wall stuff. I suppose it is more common.

I'm pretty set on MIG. I know someone with a TIG machine but I own a MIG machine with a spool gun. I can do MIG on my time but I would have to coordinate TIG time.
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Old 11-26-2016, 10:37 PM
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Originally Posted by DreamWeaver21 View Post
I saw that one. It is too wide IMO for this boat. The boats claims to be a 17 footer but it feels more like a 16 to me. I have never pulled a tape on it though. It has a flip flop seat right now which is 26" wide and I don't want to go any wider than that.

Part of the reason I am doing this is to have something to do in the evenings. I'd like to have something that works at the end of the day but looks aren't everything. This is going on a boat worth less than 4k. It looks like 1/4 wall tube is as cheaper or cheaper than the thinner wall stuff. I suppose it is more common.

I'm pretty set on MIG. I know someone with a TIG machine but I own a MIG machine with a spool gun. I can do MIG on my time but I would have to coordinate TIG time.
If you have a friend with the tig machine I would ask him to help out especially if he is good with it never hurts to learn a new welding skill.I have been welding for over 10+ years I am now teaching myself to tig weld I bought a tig machine a few years ago.I wish I knew somebody that was good with tig welding to show me pointers and what not I have the general idea I tig stuff here and there I am still trying to master aluminum it's a hard metal to weld.

Good luck with your project
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Old 11-27-2016, 06:10 AM
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I don't blame you for wanting to tackle this on your own but running a bead with a spool gun around a pipe is not for the faint of heart, especially a small diameter pipe. Unless you are some kind of special with that gun, you might want to reconsider TIG.

Also, Birdsall and other fabricators can build whatever you want. That 32" leaning post linked above is just a stock item. Pipe comes in 20+ foot lengths so making something 24" (or whatever) wide is just a matter of cutting the right length parts. You might look into that.
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Old 11-27-2016, 06:44 AM
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It's much easier to tig with a good hi-freq machine. You can weld with a start stop method and it will help with controlling your puddle.
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Old 11-27-2016, 05:31 PM
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Well, as is not uncommon with me, I have considered the advice and decided to ignore a large portion of it

I went ahead and ordered material. I have no idea what is a "good" price for aluminum tubing and flat bar. I've always just picked through scrap or been given it.

With shipping, the material to do what I want (1.25"ODx.25"wall tubing and 1.5"x.25 flat bar) is heading to my door for ~$100, so that is how far I am in to this project already.

I don't buy the idea that TIG makes a stronger weld than MIG. I am pretty sure entire aluminum ships are MIG welded together. I do accept that a TIG weld generally looks better than a MIG weld in aluminum and that it is easier to TIG thin aluminum than MIG it.

That said, a buddy of mine used my welder and spool gun to weld his leaning post / tow post on his boat. The welds look fine to me. I borrow his boat on occasion and the leaning post hasn't fallen apart from being MIG welded yet. I should mention that he did sheet metal work for years so he has more experience than I do working with metal in general.

I suppose worst case is I'll get my pieces cut and tack them together and then take it to my buddy with a TIG machine and the skill to use it.

I'll probably start another thread but it won't be a "here is how to build a professional leaning post at home" thread, it will be more of a "here is me stumbling through building a leaning post" thread.

All that being said, I know to use straight Argon but what size wire should I use for .25" Aluminum MIG work? I think I have .030 in the gun now.
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Old 11-27-2016, 06:01 PM
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Depending on the alloy ( assuming 6061 or at the very least 5083/5086 ) and linear length $100 including shipping, isn't too bad.
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Old 11-27-2016, 06:07 PM
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Yes, it is 6061 according to the site. Total of:
14ft of 1.25x.25 tube
9ft of .25 flat bar. (floor part is rounded edges flat bar, seat part is squared sided flat bar).

Instead of using tubing for where the seat goes I am going to make a rectangle out of flat bar and weld the tubing to it. I think it well be easier and it will make it easer to put storage underneath as well. It won't be visible anyhow.
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Old 11-27-2016, 06:40 PM
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Originally Posted by DreamWeaver21 View Post
Yes, it is 6061 according to the site. Total of:
14ft of 1.25x.25 tube
9ft of .25 flat bar. (floor part is rounded edges flat bar, seat part is squared sided flat bar).

Instead of using tubing for where the seat goes I am going to make a rectangle out of flat bar and weld the tubing to it. I think it well be easier and it will make it easer to put storage underneath as well. It won't be visible anyhow.
If I am judging correctly by the pic you have posted, you may not have enough mtl. assuming a seat height of 32"-36" and width of the same dims.
Also, will you be standing the flat bar on edge for the under seat storage? Otherwise 1/4 will sag under weight.
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Old 11-27-2016, 09:57 PM
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Originally Posted by vertigo View Post
If I am judging correctly by the pic you have posted, you may not have enough mtl. assuming a seat height of 32"-36" and width of the same dims.
Also, will you be standing the flat bar on edge for the under seat storage? Otherwise 1/4 will sag under weight.
I don't think it will sag with such small dimensions but as noted, I am very amateur at this. Maybe I will have to put a spine on the bottom of at least one of the longer seat parts. You are right on the material shortage though. I forgot to account for the part that the front of the seat will attach to. Basically just another flat bar cross bar up high on the leg. I can get it from home depot or find a scrap piece for that though.

Also, I intentionally didn't include the material that will be the grab bar in the back. I don't have a tube bender. I'll have to get someone else to do that part. I did a drawing in paint of all things. Probably should have done this before I ordered material . This will be enough to get me going though.

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Old 11-29-2016, 02:39 AM
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Originally Posted by DreamWeaver21 View Post
.
I am pretty sure entire aluminum ships are MIG welded together.
Probably true. However they're more likely to be using a push pull gun with many hours of practice behind them. There's no doubt in my mind you can do it with the spool gun, it just won't be pretty. You can clean that up with a grinder or die grinder though. I wouldn't hesitate to try it if I was so inclined.

My next purchase is going to be one of the AHP 200amp TIG machines off Amazon. They review really well for an entry level TIG. There's only so much you can do with MIG. Love working with metal though. I think I missed my calling in life.

Post build pics if you don't mind.
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Old 12-02-2016, 07:34 PM
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Originally Posted by ovrrdrive View Post
Probably true. However they're more likely to be using a push pull gun with many hours of practice behind them. There's no doubt in my mind you can do it with the spool gun, it just won't be pretty. You can clean that up with a grinder or die grinder though. I wouldn't hesitate to try it if I was so inclined.

My next purchase is going to be one of the AHP 200amp TIG machines off Amazon. They review really well for an entry level TIG. There's only so much you can do with MIG. Love working with metal though. I think I missed my calling in life.

Post build pics if you don't mind.
My material came in Wednesday so I spent a few hours on Wednesday and Thursday in the garage getting my frame together.

Few practice welds. Yes I suck at welding, I know.






Enough practice, time to lay out my seat. Trying to make sure it is square



Tacked up...



Welds ranged from horrendous...


To passable...


I ended up with 1.25" OD 1/4" wall tubing. It is THICK.



I ran a practice weld joining the tubing to the flat bar. This was my first try. Ignoring my huge tack, I think it looks good!



Unfortunately, when I started working on my production piece, I went all silverback on it and did a gorilla weld. Practice on the left and production on the right



Add front legs...



Add feet...



Rear legs and cross bar and the frame is done!




Very little scrap even.


Now I need to fab a seat which means fabbing a seat base, finding foam, and finding cover material.

I messed some things up like drawing a line for the rear legs and lining the front of one leg up on it and the rear of the other, but overall I think it came together OK. I am only $104 into it at this point and that is the material and shipping cost. Pretty pleased with the place I bought the material from. I measured every cut and they were all 1/16th over my desired length (my tape may be off that much). The material was all clean, straight, and well packed for a reasonable cost.
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Old 09-25-2018, 07:02 PM
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So much bad advice here. Spoolgun is fine.
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Old 09-25-2018, 07:36 PM
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Originally Posted by josahall View Post
So much bad advice here. Spoolgun is fine.
Your comment would have been helpful 2 years ago.
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Old 09-25-2018, 07:53 PM
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So, how'd it turn out after completion?
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Old 09-25-2018, 08:36 PM
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Use schedule 40 pipe. It will have lot's of thickness for welding.
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Old 09-26-2018, 08:57 AM
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I was going to ask whether he was planning on using aluminum or copper, to bad this thread is 2 years old.
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Old 09-26-2018, 09:29 AM
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Originally Posted by nvme9361 View Post
So, how'd it turn out after completion?
Well 2 years later, it is still holding up.

I cheaped out and used plywood for the seat (with 1/4 round on the edges)


Draped some Amazon foam over it.


IMG 0846
Covered with some Amazon fabric.


IMG 0848

BEFORE



AFTER
Built a little tackle tray and installed it on the boat. Not pro work but it was a fun little project and I have less than $200 in it!


IMG 0849


IMG 0850


IMG 0853


IMG 0854
There is a door on the tackle tray now. I guess I didn't have it for the pictures. I just folded the fabric over and stapled it. The folds don't bother me at all on this project. I also like that I did the cushion all down the sides because the leaning post is the perfect height and spot to lean against sideways or sit on with my feet on the gunnel and a fishing rod in my hand. The flip flop seat basically sucked all around.

Last edited by DreamWeaver21; 09-26-2018 at 09:37 AM.
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