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Thanks to a few of Lanses' post on here I have been inspired to attempt to repair a broken vise I have. My welding skills are in their infancy so I will not attempt to weld it up. I do braze everyday ( refrigeration) using 15% up to 56% silver braze. I am comfortable with this ,but I have not used brass/bronze brazing rods and I have few questions.1: Do they have the same capillary action as silver braze? Does it draw itself into where the heat is or does it just puddle up?2: Do I use regular brazing rods or the silicon bronze tig rods?3: I have noticed people using flux coated rods and dipping rods, but I have not seen anybody flux coat the part like we do with bare wire silver braze. Is it done or is that for silver braze only?The vise is cast iron and the movable jaw has been broken off. Just the part where the replaceable pad bolts into the top portion of the movable jaw. Basically i will be brazing in a permanent pad made of steel.I will be using oxy/propane for the heat and I plan to preheat the piece before brazing. No carbide burs so I will use side grinder and belt sander for prep work.Thanks
Reply:The brass will flow if you can get the cast iron clean enough. It will not flow quite as well as silphos or silver solder. Adding flux to the cast iron is good but difficult to do in such a way as it will stay. As with all brazing and soldering processes prep is the key. For flow brazing heat needs to be applied to a very large area and a lot of it. It'll take a lot more heat than you think to get it hot. Here's some that I did recently. http://weldingweb.com/vbb/showthread.php?t=251571 I posted a pretty thorough comment in this thread on brazing. http://weldingweb.com/vbb/showthread.php?t=253431Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:1. Yes, you just need to open up the gap a bit compared to silver brazing. But you can get bronze to flow a very long flow length. 2. This LFB rod and flux works better than any other I've ever tried. The flux soaks off almost as easily as silver flux. And the rod flows beautifully http://www.cycledesignusa.com/lfblight.htmhttp://www.cycledesignusa.com/brazage_lfb.htmThe next best I've used is Gasflux C-04 rod and their blue flux. The flux is a lot more difficult to remove, but the rod flows really nicely. 3. I use the paste flux and coat everything liberally. Not the common practice, but key for me during extended brazing sessions. 3a. Hopefully the propane/oxy can put out the BTUs to get the workpiece up to an even temp to promote the capillary action. I've seen some bike builders struggle using MAPP and propylene with LFB.
Reply:Here are some pics of what I am dealing with. I dont think its going to be too serious, then again ignorance is bliss. Its a 4 inch columbian vise. My plan is to add a 1/2WX3/4HX4L piece of steel to the ledge to create a solid surface to weld a "jaw" onto. I am not sure what would be the best route to take. My first guess would be to tin both the vice surfaces and the "filler block" with braze. Then set it up and heat it to where the braze would melt and let both pieces meld together. I guess it would be tin and sweat. Once both piece have bonded then start building up the areas I want to for reinforcement.The next best guess at an approach is to bevel the cast iron and braze the filler block in as if you would normally do it.I do have acetylene and I plan on preheating the entire piece on gas burners I have. Gotta put the kiddies to be, Talk more later.Thank you both for your help. Attached Images
Reply:That's a good vice right there. Columbian 604? I have a couple Columbians. I those vice jaws are supposed to be pinned on. I would make a jaw to go up and over to match the other side and pin it on like it was originally. The older units were pinned on the newer ones screw on through the face of the jaw Brazing it also would add some stability too. I would try to make it one piece if I could. The less stuff you stack up the better off you will be. I would also consider cross bolting the replacement jaw into the vice also to avoid brazing it to keep it removable so it can be reworked or replaced when it needs it. The pins would go down and the bolts would go through the face of the jaw and into the vice horizontally like the new style Columbians.Last edited by atari; 03-31-2013 at 10:40 PM.(Home)Miller Maxstar 152 (sold)MM211/spool gunLincoln AC 225C(Work)Dynasty 350Powcon 300STLincoln SP-175TWeldlodgic AWS150sWeldlodgic AWS300Custom Resistance seam weldersCambridge Vacuum EB weldersI smell something burning.
Reply:Well after sleeping on it I think what I am going to do is bevel the top broken spot back so that the braze can get down to the bottom of the "filler" piece. For the bottom I think I am going to drill the filler to accept the 3 pins and pin the bottom.I would like to make a single piece and do what atari suggested but I dont have access to a mill.I will start gathering the pieces this week and maybe get it done this weekend.
Reply:I wasn't going to bother uploading the movies I made a while back for brazing. One reason was because I didn't like how they came out and another was the battery on my camera gave out before I got done. However with so many brazing questions lately I decided to upload them. I've got one somewhat ready for viewing though it's not really finished. It'll be tomorrow before I get the other (it takes like 8 hours to upload one of these on my connection). It's not a finished product but maybe it'll help you understand the amount of heat I'm talking about. This is a small piece compared to your vice and I'm using large acetylene tips on a AC5 tank to get enough heat. This video just covers the first step in this small joint. The next video is longer but only covers getting most of the backside done. BTW that's not camera shake (it was on a tripod) but rather youtubes attempt at eliminating camera shake. I let them automatically optimize the video but it was only the lighting that needed it. If you can get enough heat into it flowing the brass down into that gap won't be a problem. I would recommend that you file or use a carbide burr for final prep of the cast iron. Grinding will smear any carbon and cause problems getting good flow and bond. Here's some lousy phone pics of the almost finished product in the video. I didn't get any after machining the surface flat. Attached ImagesMillermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Irish, you done got me scared now! Nope I aint got heat like that, but its already broke. If all else fails I guess I can try the 7018 rods and give yall something to laugh at.Last edited by cold1; 04-01-2013 at 11:41 PM.
Reply:Don't be scared but do be prepared. I'm just trying to help you get a handle on what you've got to do. You mentioned a gas burner. That could be a good start. If you set the piece up on the burner and insulated it in some way you could go a long way in getting enough heat in the piece. I once setup and brazed a large pulley with a gas burner (large cast iron water heater type burner) and stacked firebrick, sheets of steel and other forms of insulation around it to allow me to heat the whole piece evenly. I must say that it was hot work brazing it with all that heat going. If you'll look at the pictures where I brazed the pump jack bearing mounting bracket in the following thread you can see where I stacked fire brick around the piece to help hold the heat in. In that case I used my large oxy propane rose bud to apply the initial heat. When I did the original repair of that area I didn't take pics but I had fire brick stacked around and on top of it with that rose bud going in from the back while I attacked the repair area with the same 70 cfh heating tip shown above. http://weldingweb.com/vbb/showthread.php?t=251571Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Well it worked. I am stilll new to metal working so I dont have much in the way of a proper area for working. SO instead of kicking it old school, I was kickin it 3rd world and working on the ground.First time using brass rods. They do flow like silver braze, its somewhere between 15% and 45% silver. It is can be thick in the puddle and it can flow easily. It will follow the flux and heat when the base is hot enough.Prep work was done with grinder and then I used a file to take away the all the grinder marks. I did this hoping that the layer of smeared carbon and graphite left from using the grinding wheel would be removed. The new piece was flame cut from a piece of 1/2 plate I had and the all corrosin and mill scale was removed from the surfaces that would be brazed. I am new to metal working so setup tools and jigs are something I still need to aquire. For this I used a small rectangular magnet to hold the new piece in the proper position. I then used the braze to to tack the new piece into postion. I tried using clamps but there werent any good surfaces to use that would allow the piece to sit where it needed to be.The setup I used is the small uniweld torch with a double rosebud. Running Propane and oxygen. For intial heat my inner flame was about 1/2 to 5/8 long and neutral to carbonizing. 3/32 rods and granular flux, both hobart.After tacking it up, I added plenty of flux to the surfaces and really started heating things up. The flux melted and flowed nicely. I started on the "ears" where the vise is its thinest. Once I got the rod to start flowing, I started walking my way across the entire piece. When I hit the heavier sections I slowed down and concentrated the heat more in a confined area, this allowed the base to heat through and melt the rod in the gap that was between the new piece and the base.Once i was done brazing on the top side, I switched over to the face side. There was a beveled gap between the new piece and the base. I added flux and heated. Once the area was hot enough I started adding rod. I started on the far side and walked the heat and rod across the gap. Once it was full, I played the heat back and forth over the area so that It would soak in good and let the braze fill any voids I left behindOnce the intial pass was done, it was nothing more than build up after that. Build up went much faster because the "butter" layer did not need as much heat as the cast iron vise did to allow a puddle to form. I did play with the puddle and torch to see how the torch reacted with the puddle. Torch closer and bigger puddle, torch farther away and the puddle would get smaller. When the puddle was smaller it was thicker, more tike mud than water. This is the same with silver brazing, at least for me.I am letting it cool down now. Once that is done I will break out the grinder and start shaping the braze and cleaning up the piece. Attached ImagesLast edited by cold1; 04-07-2013 at 12:32 PM.
Reply:Here is the pic of the torch. Its made by uniweld. The heads are soft copper and they are to be bend so that you can heat from two differnt areas at the same time. These had been bent so many times that the copper had work hardened, I had to anneal them to get them somewhat straight. I also wanted to thank Irish Fixit for the advice and encouragement. Thanks to Lanse and his vise videos too, they made me want to repair this old thing. Attached ImagesLast edited by cold1; 04-07-2013 at 12:29 PM.
Reply:You're Welcome.Looks like you got good flow. Good job considering what you had to work with. I've wished for a tip like that a few times but I've never gotten around to getting one. I do some refrigeration tubing work on occasion with silphos. Yes brass acts much like a low silver brazing alloy. It's got a narrow temperature range where it's thicker (like you say muddy). While building up you have to get enough temp in the surface for bond while not getting to much heat in the puddle for it to flow off on you. That's the tricky part to brass and is easier with acetylene than with propane. Propane makes a great gas for flow brazing since it heats a large area. While acetylene makes a good gas for building up.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:Here are a few pics after it was cleaned up and finished. I can see a few spots with flux inclusions and I didnt get enough heat on the entire piece for great flow. I think it will hold. If not I willl do it again.I do plan on adding a removable jaw a little later. Plan on drilling and tapping the "new Peice", still got a little file work left to do on it now. Attached ImagesLast edited by cold1; 04-07-2013 at 03:26 PM.
Reply:Looking good. I think it'll likely hold for a long time if you don't abuse it. Yes you could of gotten a little better flow down into that crack if you'd had more heat. It's hard to heat up that big a chunk of cast iron without some form of oven and then being able to braze on it while in the oven is another story. I think you did very well on this.Millermatic 252XMT 304'sDynasty 280DXHypertherm PowerMax 1250Miller Trailblazer 302 EFIOptima PulserXR feeder and XR Edge gun and more athttp://members.dslextreme.com/users/waynecook/index.htm
Reply:looks great!' |
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发表于 2021-8-31 22:49:15