Steady Rest Failure

[YYCHM]

Sooooo, I was parting off on my 7X12 today, things were going well when the tool started grabbing and stalling the lathe.





Twice it stalled, I backed out, tightened everything up and went back in at a very slow tool feed rate. On the third attempt the steady rest let loose.

Do you think this can be welded back together with any success or is it a write off? By the brittle appearance of the fracture I think it's cast iron.

Kind of ruined my day actually.

 

[ducdon]

WOW. Lot's of forces involved there. Just curious but what did the setup look like. Where were you parting relative to the location of the center?

 

[Dabbler]

It looks like a write off. This style needs a lot of strength to resists the forces, and brazing isn't nearly strong enough.

 

[YYCHM]

WOW. Lot's of forces involved there. Just curious but what did the setup look like. Where were you parting relative to the location of the center?

The piece I was working on is depicted at the top of the images. It's approx. 3 3/4" long. On the left you can see where the chuck jaws left their marks. Moving right you can see where the steady rest rollers left their marks approx. 1 1/2"" from the right hand part of the piece. Moving right from there you can see the cut I was making, approx 1/2" from the steady rest.

 

[Bofobo]

Were you using cutting oil to part? Mine never had rollers i think thats neat! Agreeing with the non salvageable status though, thats rough luck

 

[John Conroy]

That sucks! Looks like after they carved out the slot for the roller finger, then drilled a big hole for the bolt, there wasn't much material left to provide the needed strength.

Might be a fun project to build a better one.

 

[ducdon]

That sucks! Looks like after they carved out the slot for the roller finger, then drilled a big hole for the bolt, there wasn't much material left to provide the needed strength.

Might be a fun project to build a better one.

I was having similar thoughts. The adjusters could all be reused. Just make the body a little beefier.

 

[DPittman]

If you are good at brazing you could try to braze on some steel strapping/bar on each side? First braze the little bit "meat" material that broke and then use the strapping to strengthen. Not much to loose but the cost of brazing and some time.

 

[YYCHM]

So, brazing is the only option here, I can't take it to a welding shop and kindly ask fix please?

 

[DPittman]

Well a welding shop would probably use a brazing technique also if they would even attempt a fix. If I was closer I would offer to do it myself for you.

 

[ducdon]

TIG Brazing with Silicon Bronze Rod is the ticket for cast iron repair now days. Trillion Welding in Calgary should be able to do the process.

 

[YYCHM]

Well a welding shop would probably use a brazing technique also if they would even attempt a fix. If I was closer I would offer to do it myself for you.

Where are you and thanks for the offer!!! May have to take you up on that offer and mail it to you if I can't find a replacement.

Never realized how dependent I was on those things until I didn't have one. Project came to a screeching halt.

BB has one for their 7X12 on sale for $60 right now. I'll be checking it out tomorrow to see if it will work on my machine. Fingers crossed.

 

[RobinHood]

So, brazing is the only option here, I can't take it to a welding shop and kindly ask fix please?

That would get the two parts back together - but would not be strong enough, as you have discovered already. I would then bolt two rings on, one on each face (like they made theirs in the video - except they welded everything) to give it the strength it needs. It would never break on you again if you reinforced it. You have nothing to lose as right now you only have a paperweight.

 

[Tom O]

Worse case you can keep the base, chop off the top and bolt on a new top that shouldn’t be too hard to make.

 

[Dabbler]

Tom Lipton (oxtools on youtube Built a 16" steady rest for one of his lathes and documented the entire process, if that helps...

Just brazing wont hold together very well as brazing does decrease the strength in the surrounding cast iron, even with preheating and all the other precautions.

This looks like a 'walking' failure: when the steady rest is out even ,005 from centre, the piece begins to 'walk' out of the 3 jaw chuck... If this was occuring, (and maybe it wasn't) It exerts very large forces on the 3 jaws - that force comes from the force on the steady rest and on the cutting tool...

 

[YYCHM]

I'm convinced the roller bearing fingers I got from LMS are the culprits in this case. They were quirky from the get go. Once you had the fingers hand tightened to the work piece, tightening the lock down bolts would bind the bearings even tighter. Had a bearing fail the first time I attempted to use them. Perhaps that's when the frame actually cracked? With the bearings to the outside of the frame I imagine they canted out when tightening the fingers. Then tightening the lock down bolts would have forced them back into alignment causing a bending moment on the frame. The original fingers without the bearings aligns the bearing force to be inline with the center of the frame, much less likely to cause any bending.

Live and Learn.

 

[historicalarms]

I was wondering how that little lathe would have enough power to snap that casting but your idea on the bearings causing a "kink" to the operation might hold merit.
If that $60 replacement from BB will fit that is definitely the cost effective route to take. If it wont fit then I would have that casting welded up...not with bronze but with Nickel rod. Weld it up solid and then re-cut the jaw pocket. I have had industrial cast pillow-block bearing mounts re-welded with nickel rod that held for years and under many multiples of force more than your lathe will ever put on it.
I think I would also take the others advise and fish-plate the sides of the "ring" just to stop this from happening again.

 

[YYCHM]

I got lucky..... the BB offering is almost an exact duplicate of the failed rest. I'll have to give some thought on "fish-plating" the sides of the ring. Those bearing mounted fingers are going into the scrap bin.

 

[Tom O]

Well if you do replace it I’d hang on to the old base for future accessories you want, a dial indicator or lathe stop perhaps.

 

[YYCHM]

Well if you do replace it I’d hang on to the old base for future accessories you want, a dial indicator or lathe stop perhaps.

Believe me, I don't throw anything out. Restoring that rest will be a future project.