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welderboy12
12-03-2004, 07:36 PM
Im getting my new mig welder in about a week :D , im wondering what size gas bottle i should get? About how many spools of wire will a 40 cubic tank will last through :confused: ? I will probaly alot of welding the first week i get it. I really need answers fast ny dad is planing on going in about a week! :eek:

mking7
12-03-2004, 08:04 PM
Im getting my new mig welder in about a week :D , im wondering what size gas bottle i should get? About how many spools of wire will a 40 cubic tank will last through :confused: ? I will probaly alot of welding the first week i get it. I really need answers fast ny dad is planing on going in about a week! :eek:

Get the biggest one you can afford and handle. My buddy bought an 80cf so I bought a 125 and after getting mounted on my machine I wish I had gone bigger. The bigger the bottle the less often you have to refill and the cheaper the refills are....

hankj
12-03-2004, 10:50 PM
12,

A lot of it depends on how much room you have, how close you are to the supplier, and stuff like that.

Have you decided which gas you want to use? A tank of C-25 will go away at 20/25 CFH, so it's easy to figure how long it will last. 20 pounds of CO2 will last you through 1.25 ten pound rolls of .030 hard wire.

CO2 is definitely the cheapest way to go, but it is not the best gas for welding light guages because of the deep penetration charachteristics. You can expect to pay about the same for a 20# CO2 tank and an 80CF C-25 jug - around $130. I wouldn't try to buy smaller - the price break is better for the bigger tanks.

Good luck.

Hank

cope
12-04-2004, 07:54 AM
I think that the 125 is a good option. I used to like the 80 for small welders but the price difference is only $10-15 for the cylinder and less on refills. With a 200-250 amp machine the 225 size is not a bad option. As already mentioned it all boils down to how often you weld and how much room and money you have. The 225 gets tiresome to transport back and forth.

Terry Lingle
12-04-2004, 09:13 AM
safety can be a bg concern as well. What ever high pressure bottle you end up with it must be secured. If you are mounting the welder and bottle on a mobile cart the heavier bottles require larger wheels and a wider stance to prevent tipping over. They also need a bigger support and clamp frane for the bottle .

My solution was to purchase a small bottle to carry with the machine in a rack plus the largest I could get as a main tank, I got a pigtail with a check valve in it from my supplier and built a transfer station next to the home position for the mig machine to recharge the little bottle at my convenience.

a better solution might be to buy 2 smaller bottles that your cart can handle safely and refill the empty as soon as you change it if you are welding a lot. What ever you end up with the bottle must not make the cart unstable.

Terry

heyfishguy
12-04-2004, 01:25 PM
I just recently bought a MM175 and in the manual and video that came with it it says to set the gas at 20cfm. I took a welding class and they said that if you are in a closed garage to set it at 8 cfm. If you are near the garage door and it is open then probably set it at around 10 -15 cfm. And if you are outside and it is not windy then 20 cfm. So I have been welding in my garage all week with the bottle set to 8cfm and it has worked great, and at that setting it will double how long the gas lasts. The instructer said that the welding companies always say to set your bottle at 20 cfm to simplify things so that you always get good welds without having to think about air drafts, and whether you are inside or out. The whole welding class was taught with us welding with the bottles set at 8-10 cfm. Hope this helps.

KBC Welder Man
12-04-2004, 02:41 PM
12,

A lot of it depends on how much room you have, how close you are to the supplier, and stuff like that.

Have you decided which gas you want to use? A tank of C-25 will go away at 20/25 CFH, so it's easy to figure how long it will last. 20 pounds of CO2 will last you through 1.25 ten pound rolls of .030 hard wire.

CO2 is definitely the cheapest way to go, but it is not the best gas for welding light guages because of the deep penetration charachteristics. You can expect to pay about the same for a 20# CO2 tank and an 80CF C-25 jug - around $130. I wouldn't try to buy smaller - the price break is better for the bigger tanks.

Good luck.

Hank

When you say 20 pounds of CO2 will last through 1.25 ten pounds of .030 hard wire. are you saying a 20Cf tank will last over a 8in spool? beacuse if you are i'm might consider making a dual cylinder rack.

hankj
12-04-2004, 03:33 PM
KBC,

No.

CO2 is sold by weight. The actual vapor volume is significantly greater than 20 cubic feet. CO2 vapor = .12341 cu. ft. per pound of CO2, so a 20# tank will give you ~162 cu. ft., or approx. 8 hours welding time at 20 CFH.

A 20 cu. ft. tank discharged at 20 cu. ft./hour will last 1 hour!

Mike W
12-04-2004, 03:51 PM
If I did the math right, my 50 pound CO2 cylinder will last 20 hours at 20 cfh. :D

hankj
12-04-2004, 04:01 PM
Or keep your keg cold for 3 years!

Hank :D

KBC Welder Man
12-04-2004, 07:46 PM
I just recently bought a MM175 and in the manual and video that came with it it says to set the gas at 20cfm. I took a welding class and they said that if you are in a closed garage to set it at 8 cfm. If you are near the garage door and it is open then probably set it at around 10 -15 cfm. And if you are outside and it is not windy then 20 cfm. So I have been welding in my garage all week with the bottle set to 8cfm and it has worked great, and at that setting it will double how long the gas lasts. The instructer said that the welding companies always say to set your bottle at 20 cfm to simplify things so that you always get good welds without having to think about air drafts, and whether you are inside or out. The whole welding class was taught with us welding with the bottles set at 8-10 cfm. Hope this helps.

After I read this I went out and tried it. Maybe my regulators off but when I tried it at 10CFH I got a kind of redish brown something around the weld instead of black, The garage doors were shut and I used the same parameters for 20CFH and the 10CFH. :confused:

hankj
12-04-2004, 07:54 PM
KBC,

The "reddish-brown" is what I expect to see. It's silicon from the solid wire, and brushes right off. I'm not used to any black stuff. That spells soot to me, and there shouldn't be any unless you've figured out a way to weld oak! :p

Hank

KBC Welder Man
12-04-2004, 10:46 PM
KBC,

The "reddish-brown" is what I expect to see. It's silicon from the solid wire, and brushes right off. I'm not used to any black stuff. That spells soot to me, and there shouldn't be any unless you've figured out a way to weld oak! :p

Hank

I may not be cleaning my base metal enough. I'll shoot a pic and put it up threemorrow. so what your saying is silicone or brown crap is OK so and it doesn't mean anything causing pososity or anything?

hankj
12-04-2004, 10:57 PM
KBC,

Correct. Brush it off and look at your bead. If it looks good, worry no more!

Hank

Smitty
12-05-2004, 12:24 AM
Its easy to tell if you have too little gas- you will get pinholes or aero bars as we call them at work.One guy welded all morning once with gas turned off and got dubbed the name aero!

Eric Carroll
12-05-2004, 01:22 AM
8 cfm ! That sounds crazy, where did they get that number. I didnt even know my flow meter went that low! :D

KBC Welder Man
12-05-2004, 12:50 PM
KBC,

Correct. Brush it off and look at your bead. If it looks good, worry no more!

Hank

Heres some pics i made in some flat iron. I just tooka flap wheel and got the rust off.

heres the one i made with 10CFH

red weld.jpg

This is the One on 20-25 CFH

black.jpg

Note this was about 1/2 in flat and i was using about tap 4 and 40 WFS.red weld.jpg

evaporator
12-05-2004, 02:43 PM
I see no pictures...

johns6
12-05-2004, 03:02 PM
When do you change or get your bottle refilled? My first bottle of C-25 is reading 0 on the PSI gauge, but I am still able to get a reading of 25 on my flow meter. Do my gauges need calibration or do I just keep using my welder until my flow meter goes to zero and my welds start getting porous?

Mike W
12-05-2004, 03:27 PM
If you still have flow, you still have gas. :D

johns6
12-05-2004, 07:46 PM
Yes, I kept on running it and finally porous welds appeared when I was out of gas. It was amazing how good it was still welding even showing very low flow readings.

hankj
12-05-2004, 09:54 PM
Well, well.

Tried a few welds with less volume. Indoors with still air, it doesn't seem to make a difference with flows as low as 6 CFM! I was surprised. Opened up the doors, and big difference, but it was expected. I guess I'll adjust my SOP to set the gas flow ~10CFM and test on a scrap, and go from there.

Thanks to heyfishguy for getting us into this!

Hank

Mike W
12-05-2004, 10:25 PM
Yeah, I will have to play with mine.

ggfossen
12-05-2004, 10:32 PM
Lucky me! I learned it, and I don't even have my welder yet!

Gary

Roger
12-06-2004, 06:17 AM
Well, well.
I guess I'll adjust my SOP to set the gas flow ~10CFM and test on a scrap, and go from there.
Hank

Your shielding gas cylinder would last 8 minutes if it contained 80 cubic feet of gas and 30 minutes if it contained 300 cubic feet of gas. Your should use about 20 CFH flow rate. ("H" stands for hour.) 10 to 15 CFH is on the low end of what's possible MIG welding.

hankj
12-06-2004, 11:23 AM
I think everybody recognizes the mistake...

Hank