welding lathe casting

[gearhead]

I have recently come across an older lathe that has an upper corner of the casting broken off. Looking into the broken portion of the casting I can see the gears and internals. The piece that is broken off does not effect or have any relationship with the accurancy of the lathe. It is just the top corner portion of the casting. My question is if I attempt to weld the corner back on (it broke away very cleanly and fits perfectly back in place) will the added heat to the surrounding cast iron walls damage the gears or warp the area out. The thickness of the area that is broken off appears to be around 1/2 or more. Again it is not in a critical area of the lathe but I don't want to have weld material falling into the lathe gearing. I plan on grinding the weld off and contour the repaired corner to match the rest of the machine. I have not purchased the lathe yet, but if the repair could be done, I'll probably buy it. Your thoughts.......gear

[abtanner]

To seal out dust, chips,grim etc.

Epoxy, when structrual integrity is not compremised. Sand smooth, paint to match and let 'er rip--turn.

[R W]

Try JB Cold Weld or the appropriate Devcon product.

R W

[SkidSteerSteve]

... The piece that is broken off does not effect or have any relationship with the accurancy of the lathe....

Kinda depends on just how accurate you are wanting to be. I've run machines in the past that we had to let it "idle" for a while to make sure the gears and drives were up to operating temperatures. Otherwise the machine would "grow" by a thousandths or two during the turning. Just something to keep in mind. SSS

[gearhead]

SSS,


I have heard about that growing process from other machinist. What would be better welding or epoxy? Gear

[SkidSteerSteve]

If is just a "cosmetic" piece of the casting, then I would stray away from putting any extra stress of welding on the work, so I'd go with an epoxy or some other cold process. Also, once you get it set up, run the machine through its paces to make sure everything is still in spec. Of course, it again goes back to what you are going to be using it for and just how accurate you need the work to be. I have a friend that picked up an old lathe for one dedicated purpose. He hard surfaces round stock and his only requirement was that the chuck turned, and had a tail stock. Taper adjustments and steady/follow rests would have been in the way. All it does is rotate the stock in front of the gun. Now if you are cutting your own bearings, that's a little different accuracy story SSS

[SkidSteerSteve]

just out of curiosity, what brand/size is it? SSS

[gearhead]

It's a Lodge and Shipley lathe, don't really know the overall size. When I first saw it, I was just kind of dumb struck. It was in very good shape and appeared to have little use (except where a fork lift spanked the casting). This machine is bigger than I can ever really use (maybe a 10 foot bed) but you know I'll probably buy it if the price is right. I have a thing for old machinery...gear

[SkidSteerSteve]

Nothing wrong with old gear. I have stuff that is older than I am, and it gets worked almost everyday. One of the quirky things about the longer lathes is that you can get them pretty cheap sometimes. Mainly because there's a much smaller market for the longer ones. Most people are looking for 60 inchers and down, verses the big ones that take up so much floor space. I'm waiting to run across a good 20X80 with a gap bed. That has always been a good workhorse that will handle just about anything in a job shop. Anything bigger, I don't want to mess with in the first place. SSS

[triggerman]

my $.02

I would at least tack it in place. If you're concerned about it growing, I suggest a good long preheat (I use an electric heat gun) and then tack it in three or four places, fill the cracks, countour and paint. Few things make me angrier than "fixing" something like that and have the piece fall out later when it gets smacked by something.

[SkidSteerSteve]

So happens I was out to dinner last night with some friends. One of which just happens to be a retired machinist and lead tech for a machine tool manufacturer. I mentioned your situation to him. After a brief "been there, done that" chuckle, he did have a suggestion. He said that in some cases they were able to bore through the piece and back into the main casting and bolt the broken part back on either with a bolt and nut, or by boring and tapping an acceptable area of the machine. You could either bore from the front and bolt back into it or come from inside the machine and tap into the broken area. This is very subjective to each case as far as what will work. He also mentioned that if you bolt from the outside in to counter sink the bolts if possible. Use this along with the epoxy/body filler/sand/prime/paint idea. I think I would make sure and use some red thread locker as well. SSS

[gearhead]

Kind of leaning toward epoxy right now. My reasons are the ease of making the fix. You mention your buddy had the idea about drilling and tapping the broken piece into position. That was a great idea, but how did he deal with the dust material or debris falling into the gears and internals?

If I have to I will remove the rear portion of the casing off, but as it was mentioned the part that is broken is in a non critical area or what appears to be a non critical area. I won't really know until I get the machine up to speed and warmed up.

[SkidSteerSteve]

Well, to be honest, we got side tracked before finishing the conversation. I have an idea that he would have said to tear the gear box down, fix it, clean everything and reassemble. Of course that would be coming from somebody that did it for a living, not as a side project If you're just drilling, I've controlled contamination in the past by masking off as much as I could and getting a couple of strong magnets (the larger, the better) and sticking them around where I'm drilling. Old speakers work good. If you drill slowly, then they will catch most of the chips (obviously, this only works on ferrous material) and the masking would stop the errant ones. After that, get the old shop-vac and clean before removing the masking. Just a thought, I don't know if you would have room or not. SSS

[gearhead]

Thanks to all who gave a response. I'll keep you posted if I buy the lathe and how I made the fix..... GEAR

[JonnyTIG]

On the topic of drilling, a vast quantity of vasoline or grease spread and lumped over the drilling point has save me by catching chips and bits.

Jonny