Lathe Question

[ToddFarr]

See what happened talking about a steerer replacement

Back to the forks on the lathe, I assume they weren't put to any high RPM, is it?

I run ~ 250 RPM-350RPM (depending on tool and crown material) if I have to cut a race after legs are brazed. There isn't enough eccentric mass to cause any problems, my lathe is however mid-sized with 12" swing 1.375" spindle bore. I probably wouldn't try it on anything smaller. I also always make sure to check clearances with the spindle disengaged rotating by hand. My main safety concern is a leg catching, not the balance of the rotating fork.

-Todd

[edoz]

I run ~ 250 RPM-350RPM (depending on tool and crown material) if I have to cut a race after legs are brazed. There isn't enough eccentric mass to cause any problems, my lathe is however mid-sized with 12" swing 1.375" spindle bore. I probably wouldn't try it on anything smaller. I also always make sure to check clearances with the spindle disengaged rotating by hand. My main safety concern is a leg catching, not the balance of the rotating fork.

-Todd

This is similar to what I've done. My lathe is smaller, (10" swing 1 1/8" hole in the chuck but 7/8" spindle bore) so I've been pretty careful when I've done a whole fork. I usually do it before the legs are on, but there have been a few occasions when I didn't.

[Alistair]

See what happened talking about a steerer replacement

Back to the forks on the lathe, I assume they weren't put to any high RPM, is it?

I just run the numbers and calculate the cutting speed for a high speed steel tool bit on alloy steel. It comes out to around 160rpm.

Just as a data point, I've turned the crown race seat to size on complete forks on my 9" South Bend lathe before. That's a pretty light machine as lathes go (it's weighs around 350lbs) but it worked fine.

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Alistair.

[Jake Rosenfeld]

While appreciated, I think all the talk about cutting speeds is thread drift from the hue and cry of DANGER which is where this thread really went south.

I tried a couple times to reply but was just too pissed off and had to quit.

Yes, turning things in a lathe is dangerous. Some things more than others. These things get extra care when undertaken.

Google lathe accident? Did you also google car accident, train crash, plane wreck, nailgun injury..........

I guess this goes deeper for me than just this thread but it seems to me that society in general is leaning towards taking a limited knowledge of an action and looking for ways to apply any safety issue they can think of to it wether it fits or not.

People are so scared of danger anymore that they forgot how to use common sense and consequently they are constantly getting hurt.

At the rate this country is going you are going to need an associates degree and 12 hours of CE's a year just to use your own axe to split wood and then you will still need to do it out of sight of the neighbor lady lest she call the hatchet police on you.......

Ok, sorry, rant over. I got more but i'll save it.

[Mike Mcdermid]

While appreciated, I think all the talk about cutting speeds is thread drift from the hue and cry of DANGER which is where this thread really went south.

I tried a couple times to reply but was just too pissed off and had to quit.

Yes, turning things in a lathe is dangerous. Some things more than others. These things get extra care when undertaken.

Google lathe accident? Did you also google car accident, train crash, plane wreck, nailgun injury..........

I guess this goes deeper for me than just this thread but it seems to me that society in general is leaning towards taking a limited knowledge of an action and looking for ways to apply any safety issue they can think of to it wether it fits or not.

People are so scared of danger anymore that they forgot how to use common sense and consequently they are constantly getting hurt.

At the rate this country is going you are going to need an associates degree and 12 hours of CE's a year just to use your own axe to split wood and then you will still need to do it out of sight of the neighbor lady lest she call the hatchet police on you.......

Ok, sorry, rant over. I got more but i'll save it.

No your not your going to just use common sense

There's a difference here now but if you lose an eye arm or your life here's the truth you can do what you like in your OWN workshoo

if I was employing someone and they did something
Like that in mine I wouldn't personally give a shit if you wanted to have a rant that everyone else in industry does it because 10 of your peers do it also


I'd fire you on the spot for running a risk in my shop

[Jake Rosenfeld]

No your not your going to just use common sense

There's a difference here now but if you lose an eye arm or your life here's the truth you can do what you like in your OWN workshoo

if I was employing someone and they did something
Like that in mine I wouldn't personally give a shit if you wanted to have a rant that everyone else in industry does it because 10 of your peers do it also


I'd fire you on the spot for running a risk in my shop

I got ya Mike, I know what you are saying. I am an employer too.

Real question for you though, because its happened to me. What you you do if an employee brought this idea to you without actually doing it first?
Would you assess the risk, talk with him about it and then proceed?
It seems that once the hazards are identified the danger is lessend as appropriate precautions are taken.

Do you think you would feel the same about this task if there was a shipping block installed in the dropouts?
I mean really, its not like you are walking into a room with filled with lathes with 30 guys bent over their machines turning fork races.......

Whats the most dangerous thing that you allow your employees to do with the knowledge that its dangerous and that they are using as much caution for the task as you can imbue them with?

[acorn]

Just do it. Like Jacques said, google or yahoo Lathe Accident. These things are preventable. If you don't agree with that then don't share any knowledge if you are going to put others at risk. Nobody deserves to die because they didn't know that the way some people do stuff is dangerous.

[mattypichu]

As the OP I'd just like to say that my question has been answered. Thank you to every poster who gave a thoughtful answer. I would never hold any of you responsible for what I choose to do in my own shop. All of life is a series of personal judgement calls that each get to make for their self. Enjoy.

[EricKeller]

I feel like I'm pretty safe with my lathe and I spin forks. I wouldn't do it if I couldn't put the steerer through the bore in the spindle. I am afraid of the lathe and I stop it before changing tooling or any other operation where I have to move my hands any closer than the handwheels. Spinny things disappear, but your fingers will tell you that they are still pretty solid

The barstock comment above is well taken, I have tried to cut 3/8" tubing on the lathe and it's not a good idea. Dynamic unbalance and bending of the workpiece is a real concern in that case.

[acorn]

Yeah, let's throw all safety concerns out the window because that's how everyone has been doing it for years.

That Yale student died because of possible lack of safety standards at her school regarding use of a lathe. It doesn't matter if 900 times out of 900 everything went ok. All it takes sine little slip up, you don't set the fork correctly, or get caught up, and that's it. Event 901 = death.
http://www.nytimes.com/2011/04/14/ny...dent.html?_r=0

[Jonathan]

Ive been watching this thread with interest and I'm officially agnostic on whether its safe to turn a whole fork but I've talked to machinists about turning forks, people who own real machine shops, who went to school to machine things for industry and they say "no". Those of us who have been around awhile often wonder why newbs don't take the good advice presented to them born out of experience. I don't think experienced Framebuilders are immune to the same trait when they hear something that's inconvenient because that's what they want to do anyway and it's always been done that way.

Btw, why turn a whole fork? Why not just the steerer and crown when everything is more manageable? Seems like if you have to turn a whole fork you kinda effed up?.

[Alistair]

Btw, why turn a whole fork? Why not just the steerer and crown when everything is more manageable? Seems like if you have to turn a whole fork you kinda effed up?.

Because then you can braze it all in one shot. Less heat cycles.

I think if you have a "real lathe", then turning an entire fork is fine. By real lathe I mean something that has a spindle bore large enough to accept the steerer of the fork you're turning (no steady rest required), and is massive enough to be able to deal with the eccentric mass of the rotating fork. Arbitrarily, I'd say that's 1000lbs minimum for the machine weight (I'd be interested to hear what other have to say on that number) which would put you in the 12 x 36, 13 x 40 import gearhead lathe size range.

I've turned whole forks on my small benchtop lathe, using the steady rest, since it only has a 3/4" spindle bore. It worked out fine, but I never felt comfortable with the process. The lathe didn't have enough mass/rigidity for the op in my opinion.

I ended up springing for a VAR crown race seat cutter, rather than going for a bigger lathe.

Alistair.

[Mike Mcdermid]

I got ya Mike, I know what you are saying. I am an employer too.

Real question for you though, because its happened to me. What you you do if an employee brought this idea to you without actually doing it first?
Would you assess the risk, talk with him about it and then proceed?
It seems that once the hazards are identified the danger is lessend as appropriate precautions are taken.

Do you think you would feel the same about this task if there was a shipping block installed in the dropouts?
I mean really, its not like you are walking into a room with filled with lathes with 30 guys bent over their machines turning fork races.......

Whats the most dangerous thing that you allow your employees to do with the knowledge that its dangerous and that they are using as much caution for the task as you can imbue them with?

Ive been watching this thread with interest and I'm officially agnostic on whether its safe to turn a whole fork but I've talked to machinists about turning forks, people who own real machine shops, who went to school to machine things for industry and they say "no". Those of us who have been around awhile often wonder why newbs don't take the good advice presented to them born out of experience. I don't think experienced Framebuilders are immune to the same trait when they hear something that's inconvenient because that's what they want to do anyway and it's always been done that way.

Btw, why turn a whole fork? Why not just the steerer and crown when everything is more manageable? Seems like if you have to turn a whole fork you kinda effed up?.

I got ya Mike, I know what you are saying. I am an employer too.

Real question for you though, because its happened to me. What you you do if an employee brought this idea to you without actually doing it first?
Would you assess the risk, talk with him about it and then proceed?
It seems that once the hazards are identified the danger is lessend as appropriate precautions are taken.

Do you think you would feel the same about this task if there was a shipping block installed in the dropouts?
I mean really, its not like you are walking into a room with filled with lathes with 30 guys bent over their machines turning fork races.......

Whats the most dangerous thing that you allow your employees to do with the knowledge that its dangerous and that they are using as much caution for the task as you can imbue them with?

Jake we are not immune to new ideas ,I am not holier than thou I just stick by what I was trained as an apprentice in a heavy engineering machine shop, there were rules I have stuck by and touch wood remained trouble free ,I remember in my younger days i used to be the guy trying to cut the corners in the shop by doing x y or z and the safety guy was just a thorn in everyones side ,however my first thought would be does this guy need more trraining and are we serving him properly in that need The second would be that we have taken on work we do not have the correct equipment for, you can buy a powered crown race cutter and as a production shop it would be a purchase we would need to make, secondly could we buy a big bore spindle lathe with a chuck to take a crown race cutter and rotate the cutter not the item being Cut with a fixture on the cross slide, I'm sure folks are doing it im not comfortable with the approach of sticking an overhung unbalanced load out of a chuck.

Ive been watching this thread with interest and I'm officially agnostic on whether its safe to turn a whole fork but I've talked to machinists about turning forks, people who own real machine shops, who went to school to machine things for industry and they say "no". Those of us who have been around awhile often wonder why newbs don't take the good advice presented to them born out of experience. I don't think experienced Framebuilders are immune to the same trait when they hear something that's inconvenient because that's what they want to do anyway and it's always been done that way.

Btw, why turn a whole fork? Why not just the steerer and crown when everything is more manageable? Seems like if you have to turn a whole fork you kinda effed up?.

The general rule was scale and turning anything the rule we were taught was 3x dia sticking out the chuck unsupported if for nothing else

As for the poor girl who lost her life I can imagine how hair would get near a rotating chuck unless it wasnt tied up, secondly i have seen lathe users not used to turning get their head and eyes as close as possible to the lathe to see what is going on after they have put a cut on, thirdly the cardinal rule of working alone ,this was outlawed here in the 80s in workshops ,i dont know about the USA but if she didnt die instantly she might have lived with another member to call for emergency help

To reiterate it again but its often the human in the chain thats the weak link when it comes to incidents again, I know some aren't in pro workshops ,i have seen one accident in my time and that was brought about by defeating interlocks, and they do it for fun ,but no one gets up expecting to be worst case dead sometime today so even if a thread serves to make you think what a complete bellend the bloke on the forum is banging on about safety again in a home shop at least it might make you double take your work for today

[bencooper]

The second would be that we have taken on work we do not have the correct equipment for, you can buy a powered crown race cutter and as a production shop it would be a purchase we would need to make

Spot on. First purchase I made when I started framebuilding, after the torch but before any jigs or anything, was a set of all the cutting and frame prep tools. Not powered, but still - I cut a crown race by hand yesterday, it took 20 minutes which is probably less time than it'd take me to do on a lathe if I had one big enough.

[Jonathan]

Because then you can braze it all in one shot. Less heat cycles.

Alistair.

Ah yes. That's not how I do it so it didn't come to mind.

Are there pro machinists who would have no problem turning a complete fork/unbalance object like Mike refers to it? The two I've talked to have said no way and they had big lathes.

[EricKeller]

That Yale student died because of possible lack of safety standards at her school regarding use of a lathe.

I feel this fails to be a useful way to make a safety argument. I have to say that in my younger years I would have been a lot more blase about the Yale accitent, but now I find it heartbreaking. When our institution came through and put in new safety rules as a result of that, I was not particularly happy about it at first. To be sure, there are some things that they want us to do that are counterproductive. But as a whole, I thought about it for a minute and decided to get rid of the tools from my lab that could hurt someone. Why take the risk of someone that's too smart to follow the safety rules or doesn't know or understand them?

The risk from spinning a fork is the imbalance. It's not going to buckle and fold and turn into a whip at any speed that my lathe will go. And the chuck is still the most likely thing to grab someone's hair or lab jacket or tie. You go look at lab accidents, the big ones are getting caught in the lathe and if smart enough not to do that, then turning the workpiece into a whip. If someone is the sort to put their hand into a spinning fork, then they are an accident waiting to happen anyway and need to stay away from a lathe. It's inherently dangerous.

[bencooper]

The risk from spinning a fork is the imbalance.

Back of an envelope (literally) calculations - assuming 160rpm, an offset of 30mm (a bit more than half average fork rake), offset mass of 500g (a couple of fork blades), I get a force of 4N.

That's not very much at all.

So I'd say, assuming you're not running at silly speeds, the risk is entirely from getting caught in the spinning forks, and not from the offset mass making anything break.

[Gattonero]

Yeah, let's throw all safety concerns out the window because that's how everyone has been doing it for years.

That Yale student died because of possible lack of safety standards at her school regarding use of a lathe. It doesn't matter if 900 times out of 900 everything went ok. All it takes sine little slip up, you don't set the fork correctly, or get caught up, and that's it. Event 901 = death.
http://www.nytimes.com/2011/04/14/ny...dent.html?_r=0

That is crazy.
Before H&S laws, common sense tells you to stay alert, FFS!
I.e., I may not always use safety googles while drilling something, but I cannot think of myself leaving the ponytail anywhere 10" near a moving part, even the cooling slots of a drill. C'mon.

Still, H&S has to be enforced, as long as it doesn't become a silly "paravento" like a finger to hide yourself behind. Yay working according to law, and Yay working according to common sense. Get both.

[Dave Anderson]

.... so even if a thread serves to make you think what a complete bellend the bloke on the forum is banging on about safety again in a home shop at least it might make you double take your work for today

I think this is a good and valid point. We can probably all use a little reminder of such things now and then, and not everyone has the experience to know how to do something safely, even if it might seem obvious to others. I think, though, that its often how something is said, that raises a bit of ire, as opposed to the content of the message (*).

Dave

* NOTE: This is not in reference to any particular post or poster, its just an observation, and something that, unfortunately, seems to be common to many forums.....perhaps contributed to by the use of anonymous user names?

[progetto]

Last time I was on holidays in the islands ,there was a maintenance guy using an electric angle grinder whilst standing in the pool. I pointed out to him it may be not such a good idea, he said not to worry, he did it all the time.