my chuck got minor damage today :(

[wquiles]

I started working on the bomb-proof host project yesterday:
http://www.candlepowerforums.com/vb/showthread.php?p=2800759#post2800759

Today while working on the heatsink, just touching up the start of the threads, I got confused on the levers on the carriage and was not able to disengage the threading in time and it kept going and going towards the chuck!. Although I managed to turn off everything OFF, it did not occurred to me to use the foot brake, so while the spindle slowed down, boom ...

Luckily I was touching up the beginning of the threading and I was going really slow (68 RPM or so). The thing is, I know better. I left myself no room and I was not even prepared to use the foot brake. I need to be more careful ...

Will

 

[SafetyBob]

Been there done that Will. That was a long, long time ago and it scared the crap out of me.

Glad all you had was a little damage, could have been much worse and now you will always be reminded to be more careful, no respectful of the power of that lathe.

Bob E.

 

[SafetyBob]

If I am lucky, I will get to try that on my new 10" Bison 6 jaw that I have a day and a half to see if I will on eBay.....please cross you fingers for me.

Mac will be proud of me. $371 + 50 shipping. Of course there is the problem with the backplate I would have to pay full price for at the usual places....

Bob E.

 

[Mirage_Man]

Yikes! How'd that happen? You were cutting threads and you weren't able to dis-engage the half-nuts in time? When threading I usually engage the half nuts while the tool is at least an inch away from the part. That usually gives me plenty of time to put my right hand on the half nut lever and left on the cross slide wheel. I keep my hands there until I get where I want to stop threading. That's when I dis-engage the half nuts and roll out of the thread at exactly the same time.

 

[KowShak]

The damage to the chuck doesn't look too bad, what collided with the chuck and how did it come off in the fight?

 

[donn_]

Did the Bomb-Proof Host survive the assault?

 

[wquiles]

Well, it was very minor damage, but I felt pretty stupid last night :mecry:

Like Brian, I always have my hand on the half-nut lever, but for some idiotic reason, on the last pass, I simply did not have my hand on the half-nut level, and when I went to look for it, I think I grabbed the power feed level instead - after that did not work (duh!) I hurried to turn the lathe off, but the big inertia meant the chuck had a few more turns before stopping, but it was too late

Well, live and learn ...

As to the parts, not a perfect fit, but they worked out really well - I have to work some more on this over the weekend:

Will

 

[MarNav1]

Happens to us all. I'm just glad it was a chuck and not a finger or hand. Good luck.

 

[Mirage_Man]

Happens to us all. I'm just glad it was a chuck and not a finger or hand. Good luck.

LOL, yeah when I first got my South Bend you should have seen my knuckles :laughing:. It only took a couple of those to make me learn.

 

[StrikerDown]

Just like the first scrath on a new car, it always sucks, I feel your pain! Glad your pain was only in your gut.

Does your new have seperate levers for threading feed and the half nut?

That seems like it would be confusing til you get used to it.

Does the foot brake shut down the electrical as well as stop the spindle?

Sorry for all the questions, but I am still undecided between getting your lathe and the Griz G4003G. Like you were!

I think Grizzly is trying to help me decide, their Gunsmiths lathe went up $200 Jan 1st.

 

[Anglepoise]

There is not a machinist alive that has not had a 'crash' of some sort at some past time.
Glad your hands are OK. And we all feel for you.

 

[kromeke]

Bummer crash. I just had a student employee do the same thing to my "new" lathe at work. He thought I'd be pissed. I'm not, crashes sometimes happen to even the best of us. He was very apologetic.

I don't need to tell you now, but that footbrake can be a really cool thing to have handy. I keep my foot on mine if I'm working close and towards the chuck.

Sucks to have that happen to the hard jaws on your six jaw chuck. Looks like the damage is is a spot where it will seldom matter, but I'm not sure what kind of work you do. I know that I seldom hold rings or pipes on that step.

Yes, any machinist worth his salt has had crashes. The better one have fewer, but I don't think you can claim to be a machinist without some minor crashes in your machining.

At least the jaws are replaceable (at fair expense).

 

[65535]

The only machining crash I ever had was a case of mistaken z travel which after drilling through some aluminum bar sent the bit even deeper into the piece then moved the x axis for the next hole with the bit all the way in the hole. Lost a bit but wasn't too bad.

 

[Superdave]

I remember a guy in high school metal shop that walked away from the lathe, the bit hit the chuck and locked it up solid with a HUGE bang, the lathe survived but i think the instructor needed a new pair of pants. :naughty:

 

[Mick]

Bison will sell you new top jaws. Been there! Mine fit perfectly.

 

[wquiles]

Thanks much for the comments guys - much appreciated

The damage affects a part of the jaw that I never use (at least not yet), so everything is still in working condition, so it is not something I have to fix/replace to continue working on my projects.

I guess I better start saving for the buy-new-top-jaws-for-my-Bison foundation

Will

 

[kromeke]

Now for my constructive criticism:

If the picture is the setup, you have a poor setup. You left no room for your thread tool to exit. Or are you threading away from the chuck? In that case it was still control reversal, but you should have still given yourself more room. I assume you're working with insert tooling? Nice, rigid, and hard insert tooling? Gotta give yourself some room for error, this isn't CNC. It's your lathe, so I don't have to tell you how much you paid for it.

I don't have a six jaw. Sometime I wish I did, so I'm envious. I do have a nice three jaw with hard top jaws. I can swap out the hard jaws for either soft jaws or pie jaws. I'd get some aluminum soft jaws and bore to the size needed. A collet setup might also be better, I've got a collet chuck and 5c collets. If your working over 1", you'd want something bigger than 5c. My ideal setup would be for a 5c with taper for a pot collet adapter. This is for rings and short work greater than 1", up to maybe 5". However, if your working with long lengths of tubing, a larger collet would be in order. A collet setup can still be a victim of operator error, but if you hit something it is usually at worst, a collet. Usually the tool looses, but it is all dependant on the nature of the collision.

You have replaceable hard jaws, I haven't looked, but I assume that soft jaws are available for it. I don't know what tooling you have, you may already have a 3jaw with removable tops.

Look into your options for workholding. I don't know the nature of your work, other than this part, but I assume you got the six jaw for tubing. I know it didn't come "extra" with the lathe. You can also always make custom one-off collets or collet like things and mandrels. I always have emergency 5c collets around for the odd jobs that come through the door. (emergency collet is a soft collet that is bored to the size needed.)

I looked at your thread regarding your new lathe. Nice looking machine. I think the one I have at work is in the same class. Mine is an MSC "Prince" lathe. I wish my spindle speed would go slower, yours does. Mine bottoms out at 105, threading gets a little hairy sometimes. It is a 13"x40

Nice chuck. I like Bison stuff.

 

[Torque1st]

Just like Mick said; get yourself another set of jaws, no big deal. I second kromeke's thoughts. Always leave yourself some over travel room. Make a fixture if necessary.

 

[wquiles]

Thanks guys

I decided to give it another try today, but instead of using another heatsink and body, with the help from Daniel (Gadget_Lover), I decided to use a shallower thread than 20TPI, so I am trying 30TPI (having the levels to change threads right in front without having to change gears by hand is awesome!).

The internal threading bit is narrower and can do the 30TPI fine, but the external bit I currently have (Kennametal TopNotch threading insert) only works from 8-20TPI, so the outer threads are not as "pretty" as if I had the right tip (I will order this week), but everything worked perfectly - it is the first time for me doing both sides of the thread, designed to match each other, but with Daniel's help it worked first time, without need to touch up anything!

Well, you know me by now. I have "some" pictures to back up my story ...

Here I am starting the "tube", same ID as the actual Barbo tube:

Here I am threading the inside of the tube to 30TPI:

then I parted the piece:

I then took another piece of scrap and turned to be as the heatsink I will be using:

and this time, I am not only being extra careful, but I am also leaving myself LOTS of room. While doing this I also had the foot on the brake, just in case ...

note the threads are a little bit too thin at the crest - this due to having too big a cutter for the threads:

still, everything fit, first time, with no touch ups - Daniel would be proud

Now that I have practiced some more, I feel more confident moving to the actual hosts/heatsinks

Will

 

[gadget_lover]

Thanks guys

I decided to give it another try today, but instead of using another heatsink and body, with the help from Daniel (Gadget_Lover), I decided to use a shallower thread than 20TPI, so I am trying 30TPI (having the levels to change threads right in front without having to change gears by hand is awesome!).
< snip >

still, everything fit, first time, with no touch ups - Daniel would be proud

Daniel IS proud!

Good work Will. Actually, I'm just glad that I did not give you bogus advice.

I am SO envious. 6 jaws, quick change gearbox , AND the luck to get the thread right on the first try!



Daniel