Broken Shaper vise

[carlquib]

Here are the picture of my broken gemco shaper vise.
broken vise 1
broken vise 2
broken vise 3

I am still thinking that I will preheat, weld, then relieve, cool slowly and then machine the top. I am, however, open to suggestions on how to fix this little problem. I haven't ever tried to weld something like this vise before. I do have a fair amount of experience welding cast iron. The one thing that I am worried about is how long will the vise continue to creep? I know that cast has a tendency to creep for quite some time, but I was hoping that by stress relieving after welding I could mitigate some of the creep. Any one know what the tensile strength of this vise would be?

I tried to find the thread about the brazed in steel repairs but they must be in the old general forum because a search didn't bring anything up Any suggestions would be greatly appreciated.

-brian

 

[Forrest Addy]

Yup, as you say but use a cast iron filler not nickel or stainless. Do it right (preheat to 1200 degrees F) and the vise may not distort enough to even need overall machine work and the repair will be invisible except for a difference in the color of the welded deposit. However, it's a big hot job that few have the gumption to undertake and do well.

A post weld streaa relief is an excellent follow-on process. Be sure to slow cool it. A pit fire having plenty of ashes and coals is a perfect venue. When the work is cold follow with a few days in dry ice. The work will scale because of the heat. Spray it down before welding with anti-spatter anti scale spray from the welding supply house.

I'm sure the hay hands and shade-tree car cripplers will chime in with bailing wire expedients suited to get one more season out of an 80 year old seed drill. Don't forget you're want to make a lasting repair on a machine tool vise so try to resist them.

 

[matt_isserstedt]

Brian...I will pull out all the stops in terms of creativity for a mechanical "patch" to this problem.

Despite the disappointing brittle fracture characteristic, cast iron has a nice tendency to hold coarse machine screw threads well.

I've fixed a number of "distressed" parts this way...currently working on one in the shop now...but a little smaller.

-Matt

 

[Access Db Guy]

Of course, under the "all I got is a hammer so everything looks like a nail" school of thought...

You got a shaper. Use it.

Shape out that broken area and, perhaps, 3/4" deeper than the baseline surface. Cut yourself a hunk of metal and shape it to fit in the slot you just cut, same width, same length, and height to set in the slot and come up to the same level as the other pads.

Drill, bolt, and secure as required.

Stan Db

 

[johnoder]

Brian:

You can fix this the hot way, and as Forrest says, a big hot job.

Seems to me IMHO the real dumb way.

I would for sure go with the bolted in steel on both sides. The pre existing "scarf" would induce me to make the pre milling or shaping follow this slope and the steel would be tapered to fit, but then that is just me. The great pulling loads will come on the bolts right next to the tee slot in any case.

If you don't like the idea of visible bolts, make them invisible like the Senior Packards used in the thirties to hold the counterweights on the crankshaft. There were basically "socket head cap screws" with no socket, that were socked down and machined off flush. Good "iron" to make thse from is ASTM A193 B7

But by all means, suit yourself.

John

 

[Nick Stanley]

Has anyone ever welded cast iron with Oxy-Acetylene? The filler is just that, a bar of CI about 1/4" square. I know a local welding shop that sells it. I've got a small countershaft hanger that needs a repair. I've also heard of the Cronacast rods, anyone ever use them either?
-Nick

 

[Mike C.]

carlquib,

I'm the reinforced-brazing guy so I'll explain that, but first let me say that from a funtional standpoint, this is an excellent candidate for just a straight mechanical fix. Basically, you have solid blocks and the casting has been blown out between them. (Man, I'd like to have been on the other side of the shop to here what THAT sounded like! Wouldn't want to be in front of that machine when it ripped apart that vise!)

You could easily just plane down the damaged blocks, plus 1/8" or so deep, flip the vise over and drill for about six or eight 5/16-3/8" bolts in each block, drill and tap some hunks of steel, bolt them in place and probably live happily forever after. That's the easy functional fix.

The reinforced braze is possible, but a bit more trouble that may not be warranted in this case. If you want to take this tack, put this broken vise in a mill and rout out the damaged areas about 3/4" deeper that the lowest point. Then make up steel or iron blocks that fit as closely as possible to the routed pockets. Drill proper tap-sized holes through the blocks and far enough into the body of the vise get a good purchase with the threads. Remove blocks, drill clearance holes, and either countersink for large flat head countersunk screws or counterbore for fillister head bolts or allen head bolts. The idea is to make this fix strong enough to hold the repair by itself. Put it all back together and bolt it up solid to make sure it fits. Take it back apart if you like the fit and grind some V notches in the edges of the block and the pockets to get a good braze. Put it BACK together, screwed down tight, and head to the welding shop.

Heavily salt down the pockets, tops of the screws, etc... with granulated brazing flux. Now burn about a tankful of propane with a weed burner torch to preheat this whole works until the whole thing is a very dark dull red. Grab a big Oxy-acetylene torch with a rosebud tip and some hefty flux coated brazing rods. Commence to brazing, letting the brass flow down in the cracks between the blocks and the original metal. Fill all the cracks, fill the V notches, fill the countersink/counterbore, cover the screw heads then add enough braze to allow you to plane it off smooth (think Bondo). Let this cool slowly, no wind, no water, should take a several hours to come down.

Your shaper can heal itself now as it carefully planes the brass down to the original level. File to blend it the last couple of thou. It's there forever. The mechanical fix provides strength required and the brazing makes sure nothing ever comes unscrewed or loosens up in any way. A shot of paint and it'll be invisible. Unless somebody look REAL close and sees the fine brass lines, it'll never be noticed without paint.

Unless you KNOW what you are doing cast iron welding will proabably not be a pleasant or successful experience. Cast iron does not weld like steel, but is more like aluminum in that it gets mushy and just falls out. You MUST have facilities to preheat as above, but to a cherry red, maintain that heat while welding, and have an oven or similar to allow the work to cool down over a period of days. Oxy-acetylene welding is probably the best weld fix for cast iron, but you better know what you are doing and adhere strictly to the above or you will end up with a zone of brittle white iron, causing the weld to rip out at the root.

Worst possible fix is to slap a nickel rod to it with an arc welder. If you do not pre-heat, peen, and post heat with a long cool down, you will probably be able to watch it crack as it cools. Even with proper technique, nobody I know of will 100% guarantee a cast iron nickel-arc weld. I guarantee my reinforced brazing technique 100% for the life of the machine or me, whichever comes first.

If you go the cast iron welding route and don't get it right it will break if subjected to the slightest torsional or shearing load. You now have to grind out all the white iron responsible for this break to make the fix I have described. Even worse, if you used nickel, all THAT has to come out as well. You cannot braze nickel, it runs off like water on oil. I fought BOTH these battles repairing failed cast iron welds on the big lathe. All the old braze work held up. I didn't have to fix a single failed brazed part.

 

[carlquib]

Thanks for all the input.

Forrest, what type of material aplication would you use oxy/acet, or could I use an arc process? Most of my experience has been using some of the new "magic" arc welding cast rods. I am not sure what the exact compositions are but I have one meant for buttering and another for build up. Supposedly this is exactly the type of repair they were made for but I will deferr to your experience because I haven't made a deposit this large before, at least not one that mattered. All of the repairs have been either thin sections welded in place, blocks, manifolds, pulleys, or cast iron wear parts on earth moving and farm equipment.

I will let you all know what I end up doing when I finally figure out what I am going to do . One option that I was wondering about was oven brazing? If I machine and bolt in the steel pieces with braze and flux in place and then bring up to brazing temp? I managed to rig up a big enough heating oven by using firebrick stacked up on the big gas forge. I still think that I will need to have a big pile of hot ashes to put the vise in to slow cool it. Even with all the exhaust holes covered on the forge it still cools back down in 4 or 5 hours. Is that a slow enough cool down for something this big? All the other cast iron pieces that I have welded haven't had to hold tolerances when the weld deposit was large. If the repair moved it was fine as long as it didn't break again.

-brian

 

[Gary E]

I would not weld to repair that. Instead machine away about 1/2 of the broken pad and make an insert to bolt and pin in place.

If you weld it the distortion will mean re-machining anyway and that is more work than it's worth.

 

[George Hodge]

I found that when building up worn pump housings by brazing,that if I heated the housing to a good almost red heat,I could use a smaller tip on my torch with good results.If the housing was oily,I let the propane heater heat it till it stopped smoking.

 

[JBishop]

whatever method you use, you might want to consider making a longer tee nut to spread the load out more to hopefully prevent it from happening again. Good luck, Jim.