gordohigh Posted April 1, 2010 Posted April 1, 2010 I would like to make a new star gun and wondered what the community would recommend for the DOM tube sizes. Also, being that star sizes are pretty much standardized, how much over the star size would you go to allow for prime and a not too tight fit. I was thinking around 10% over but I haven't checked ebay for exactly what is available although I do know that there are many sizes and it can get rather confusing with all the ID, OD, and wall thickness, just takes a little time with the calculater so I would like to have a target to look for and then adjust up or down from there. I currently have only made 1/4 in, 3/8in, and 1/2 inch stars, but have also made a 3/4 inch comet pump so I guess I would like to knnow what sizes I would want for those star sizes and what for the 5th tube assuming I would have 5 tubes mounted on a 6"X6" plate? All of the tube I have seen on ebay was listed in decimal so if anyone has the sizes listed for the closest sizes in decimal that would be helpful. I know that the 10%, (if thats what it is), over may not be available exactly so would it be better to go slightly larger? And yes, I know how to divide a fraction to get the decimal but with all the sizes available it can still be confusing. Lastly, what would the wall thickness need to be as it seems that .120 is a pretty standard size. Is a little less than an 1/8 adequate or would I need to shoot for something thicker. If I use 1/4in plate it would probably be easier to weld a .250 or close to that wall thickness? I guess I've answered a lot of my own questions but I would still like some feedback from you all.
dagabu Posted April 1, 2010 Posted April 1, 2010 1/4", 3/8", 1/2", 5/8", 3/4", 1. That covers all my stars and small comets. D
gordohigh Posted April 1, 2010 Author Posted April 1, 2010 OK, so 5/8 should be in my mix. What about the oversizing of the tubes though, so the stars fit nicely once primed. maybe I'm making this harder than it needs to be but I'd like to make sure I get this right before ordering my material and I will probably have enough excess material from the order to make 2 or 3 extras which I may build and offer to another member to help pay for my expenses, although that is not my primary concern nor am I soliciting. If that even happens I will list in the proper forum.
dagabu Posted April 1, 2010 Posted April 1, 2010 My gun is just like I said, if the star is loose, its fine, less noise that way. You can over-lift to a point but the star will shatter if too much lift is used. D
Bonny Posted April 1, 2010 Posted April 1, 2010 Lastly, what would the wall thickness need to be as it seems that .120 is a pretty standard size. Is a little less than an 1/8 adequate or would I need to shoot for something thicker. If I use 1/4in plate it would probably be easier to weld a .250 or close to that wall thickness? .120 wall will be more than adequate for a star gun...I've fired 3" cans out of 1/8 wall pipe. If you can't weld 1/8" tubes to 1/4" plate, I'd suggest practicing and learning before making a star gun, just to be safe. Go with the size selection Dagabu suggested and you'll be fine.
gordohigh Posted April 2, 2010 Author Posted April 2, 2010 Thanks Bonny, I guess I'll shoot for .120. I shouldn't have any problem with the welding, although welding around a tight circle and turning out a nice looking weld can be a challenge. Some of the guns I've seen for sale online have had very poor looking welds and thats just not acceptable for me. I'm going to wait another couple of days to see if anyone else has any different ideas and if not I guess I'll go with the sizes Dagabu has. I'm wondering though, do you all shoot multiple 1/4in stars from the 3/8 tube, because my primed 1/4 in stars won't fit into my 1/4in tube. If thats the case then I may not need the 1/4 tube. My current gun was made from water pipe and standard sizes so I have had to improvise and was hoping to build this so it works out the best way possible.
Bonny Posted April 2, 2010 Posted April 2, 2010 Thanks Bonny, I guess I'll shoot for .120. I shouldn't have any problem with the welding, although welding around a tight circle and turning out a nice looking weld can be a challenge. Some of the guns I've seen for sale online have had very poor looking welds and thats just not acceptable for me. I'm going to wait another couple of days to see if anyone else has any different ideas and if not I guess I'll go with the sizes Dagabu has. I'm wondering though, do you all shoot multiple 1/4in stars from the 3/8 tube, because my primed 1/4 in stars won't fit into my 1/4in tube. If thats the case then I may not need the 1/4 tube. My current gun was made from water pipe and standard sizes so I have had to improvise and was hoping to build this so it works out the best way possible. Unles you plan on making smaller stars, if your stars don't fit leave out the 1/4" tube . If you look around at (almost anything) made with steel you can find some poor ugly looking welds.
dagabu Posted April 2, 2010 Posted April 2, 2010 I suggest MIG welding with .030 wire, use black gas pipe and a good base plate. Don't try to weld the entire circle in one go, use very hot tacks, duration of 2-3 seconds on three sides, start the weld at the end of the last tack and weld the the base of the next tack. Unless you are VERY skilled with stick welding, stay with MIG. TIG will give you very pretty welds but black gas pipe is to thick and the TIG will not penetrate enough. D
pianomistro Posted April 24, 2010 Posted April 24, 2010 My star guns are the same size dagabu stated: 1/4", 3/8", 1/2", 5/8", 3/4", and 1". I order the tubes to be about .060" larger in diameter than the star size, so it's a nice fit even after prime is on the star. I weld 6 to a 6"x 6" plate with no trouble. So my welding isn't the best. I get .120" wall on everything up to the 1", and .135" wall on the 1" one. Any larger and you're just wasting money.
Bonny Posted April 24, 2010 Posted April 24, 2010 I suggest MIG welding with .030 wire, use black gas pipe and a good base plate. Don't try to weld the entire circle in one go, use very hot tacks, duration of 2-3 seconds on three sides, start the weld at the end of the last tack and weld the the base of the next tack. Unless you are VERY skilled with stick welding, stay with MIG. TIG will give you very pretty welds but black gas pipe is to thick and the TIG will not penetrate enough. D 2-3 seconds is a HUGE "tack"... almost a stitch. For .120 wall though, you could really just do really hot tacks until the circle is covered. Otherwise, a circle the size for star guns should take 2 welds...3 at most. After making a few with the MIG, IF are ready to become a man, do it up with a 7018 and a stick welder.
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