Your ideas for a shop made O/A hand truck?

[erikmannie]

So I have definitely decided to only use O/A processes (torch cut, gas weld and/or braze) to build this cart…because it is an O/A cart.

I would love to braze the whole thing, but some of the joints are not suited to brazing, in my opinion. I know that brazing fillet & lap joints is fine, but what do you guys think of brazing butt & edge joints? I do *not* like the idea because I almost always machine or grind down my butt & edge joints to flush.

I will definitely do the nicest work that I can, & leave the cart unfinished (i.e. no paint). I will use way oil (ideally Vactra #4) to protect it from corrosion. The cart will live inside, but be used outside only. I wouldn’t spend the money to clearcoat it.

At this point, I am inclined to gas weld the edge and butt joints, and braze the fillet and lap joints. The lap joints are on the hinges. It will probably end up looking a little odd having both gas welded & brazed joints, but the gas welded joints will be ground down to flush so nobody will see those joints.

 

[erikmannie]

Here are today’s prices from my neighborhood Matheson (which has *stellar* customer service):

Customer owned 80 ft.³ oxygen cylinder, empty: $214,

80 ft.³ of oxygen: $37,

Customer owned 75 ft.³ acetylene cylinder, empty: $232,

75 ft.³ of acetylene: $71.

All of the above with California sales tax: $625.

You need an open pickup truck (i.e. no camper shell) to pick up the acetylene. I will have to borrow a friend’s truck.

 

[WobblyHand]

You need an open pickup truck (i.e. no camper shell) to pick up the acetylene. I will have to borrow a friend’s truck.

I'm not surprised about that. The explosive limit range for acetylene is very wide.

Lower explosive limit: 2.5%; upper explosive limit: 82%. From https://webwiser.nlm.nih.gov/substance?substanceId=35&catId=63
So even a little leak and a spark can cause a big bang. Keep the bottle upright and chained, not on it's side.

Those bottle prices seem high, but everything is high these days. Might want to shop around for empty new bottles. Maybe you can do a little better. Like an idiot, I lease my tanks, but at least I get to have decent sized ones. Hate to run out in the middle of a job.

 

[pontiac428]

Please reconsider using way oil as a metal finish for your cart- just clear coat it instead. The oil will get dirty and end up everywhere, and one thing you DO NOT WANT contaminating the pressure side of your O2 system is hydrocarbons. I keep all forms of oil and grease away from my gas setups. It is just as important as keeping chips off of your electronics.

I know that I am harsh about people making a big deal out of nothing, but this isn't nothing, it's your house, your shop, your tools, your family...

 

[erikmannie]

Please reconsider using way oil as a metal finish for your cart- just clear coat it instead. The oil will get dirty and end up everywhere, and one thing you DO NOT WANT contaminating the pressure side of your O2 system is hydrocarbons. I keep all forms of oil and grease away from my gas setups. It is just as important as keeping chips off of your electronics.

I know that I am harsh about people making a big deal out of nothing, but this isn't nothing, it's your house, your shop, your tools, your family...

*Such a great point*: oil near the compressed oxygen. I am surprised that I overlooked that.

 

[tq60]

You have a mill but no band saw and want to cut with gas, good.

Cut 1/8 long.

Get a end mill long enough to do full width of material in one pass.

Cut material.

Place in mill and square the ends.

Cut like pairs at same time so lengths can be same.

This does a few things.

Square ends with full thickness is target.

Cut a few coupons from the short ends of the lengths for practice.

This project is perfect for either MIG or puddle.

Mig would be better but you want to do gas so puddle it, braze is a mess.

Having the square full thickness ends means the joints will clamp tight and square.

Use a framing square to clamp to the material to assist.

Tack weld a few places to hold it.

Proper puddle will require just a bit of filler and when finished very little grinding to remove just the high spots.

Bondo when done then proper paint prep and good paint.

Place your axle such the wheels are just above ground, the cart will be plenty heavy to stand up.

Having the wheels not touching ground keeps them ROUND.

Only need 1/8 inch.

Make feet under so Only the feet touch, floors are not perfect and metal touching floor gets rusty.

Simple 1/4 nut welded on works.

Sent from my SM-G781V using Tapatalk

 

[erikmannie]

You have a mill but no band saw and want to cut with gas, good.

Cut 1/8 long.

Get a end mill long enough to do full width of material in one pass.

Cut material.

Place in mill and square the ends.

Cut like pairs at same time so lengths can be same.

This does a few things.

Square ends with full thickness is target.

Cut a few coupons from the short ends of the lengths for practice.

This project is perfect for either MIG or puddle.

Mig would be better but you want to do gas so puddle it, braze is a mess.

Having the square full thickness ends means the joints will clamp tight and square.

Use a framing square to clamp to the material to assist.

Tack weld a few places to hold it.

Proper puddle will require just a bit of filler and when finished very little grinding to remove just the high spots.

Bondo when done then proper paint prep and good paint.

Place your axle such the wheels are just above ground, the cart will be plenty heavy to stand up.

Having the wheels not touching ground keeps them ROUND.

Only need 1/8 inch.

Make feet under so Only the feet touch, floors are not perfect and metal touching floor gets rusty.

Simple 1/4 nut welded on works.

Sent from my SM-G781V using Tapatalk

Wow, that was countless helpful recommendations in one response!

I had planned on side milling the ends to length, but I would not have thought to do several equal lengths at once. I have a lot of long, large solid carbide endmills for this task.

Am I to understand that you recommend that I do *not* miter the corners to 45°? I don’t want to. Do you guys think it would be okay to forgo mitering the corners to 45°?

I am fine to gas weld the whole thing. My goal is to exceed 100% penetration by leaving a tiny gap in, say, a butt weld, & then welding it in such a manner as to have an excess of fill on the back of the seam. I do this because I almost always machine or grind the top of the weld down to flush.

For the fillet welds, this is a challenge for me with any processes other than brazing or stick. I will just have to do the best I can, as I would not take the time to file down the hard filler material to a nice radius (although I would come in with a round file to knock down the high points).

If I were to braze the fillet joints, the bronze is soft enough to file down the fillet with a round file. I don’t mind the mess of brazing, but I think it is not the best idea to have a weld seam that is part gas welded & part brazed.

This cart is definitely going to be clear coated. I like to challenge myself by having my work exposed for all to see. You can hide a lot of mistakes with paint and powder.

 

[erikmannie]

I bought the hubs. They were only $20 each & look to be perfect for this application.



I will not use the supplied (probably galvanized butter) axles. Rather, I will fabricate a single long axle.

I made the phone call (Forrest Carver at Bath Cycle & Ski) to buy some *cheap* spokes, rims, tires and tubes, but I need to get the hub in my hands to make one more measurement in order to calculate the spoke length.

Fortunately, I have a wheel truing stand + spoke wrenches, & I have taken several bicycle wheel building classes. It will take me between 1-2 hours to build each wheel, & I will probably never have to mess with the wheels for the rest of my life (unless I break a spoke).







Presently, I am planning on using 26” tires. I could also choose from 16”, 20”, 24”, 27.5” or 29”. The 26” stuff is the most affordable.

I welcome any ideas on tire width & tread type. I can’t imagine that knobby tires would be called for. I *can* imagine that the more width, the better. I am leaning toward 4” wide tires with a thick street tread.

 

[FOMOGO]

Not only dangerous, but being in a welding environment it would be filthy as soon as you started grinding, sanding, etc.. I used a hightemp, ceramic based engine clear-coat over a diluted gun bluing finish on my recent workbench project, and it seems like it will hold up well. Mike

*Such a great point*: oil near the compressed oxygen. I am surprised that I overlooked that.

 

[tq60]

Regarding metering the joints ..

Personal choice, material allows for easier full penetration but now more filler needed.

With thin material this may not be needed.

This is why I suggested practice.

You have been doing so for other process, lesson learned here applies there.

Full thickness is also easier to clamp.

C-Clamp across the joint holds in perfect alignment.

Do not get in a hurry as it can warp if you try to complete a joint in one pass.

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