Needed Shoes

Needed shoes
This is a short story just about how things sometimes work. Saturday morning I went to Wal-Mart to get antifreeze and some oil. At the check out, I had gotten some novelty Halloween gifts for my wife, I told the cashier I was getting these for my wife as her birthday in on Halloween. She told me her daughter’s birthday is also Halloween. I said something like, wow that is cool. We talked a little more, as I left she called out, "tell you wife, happy birthday from me.

Then I went on to Top Shoes but they weren’t open yet. To kill time I browsed through Hastings, looking at books. I thought even though I was enjoying myself I don’t know why I came here, I could have gone to AutoZone to get the Heater Core. This struck me cause on "This American Life" which airs on NPR Fridays at 7:00 PM. They were talking about how sometimes we do things without knowing why, it was an interesting show. You can hear the broadcasts on their web page 1 week after it airs.

So I drove down to AutoZone. I was the only customer and the guys were joking around which of course I stepped right in with their joking. I told the guy what I needed, he looked it up, as he read the part number off the screen I could tell by his expression something was up. He bent down and pulled the very part I needed with out having to move his feet. We were all astonished, I mean what were the odds, I said you must have 6000 parts in this store. He said just a minute before a woman returned this. wow… I went on to tell them the Wal-Mart story that just happened. Then he told me about his friend who he by my reckoning is obsessed with the number 11. He said when he looks at his watch or whatever the number 11 comes up. He went on a little long with his story. Then as we were walking towards the counter he added, I once had a dog that was born on Halloween. So I kind of just bopped out of the store feeling a kind of wonderment (one must enjoy the little things thrown our way).

I went on to the shoe store, this store has the various widths, like EEE or 3E or Wide depending on the manufacture’s system. When first walking in the store I held the door for this guy who seems to be hobbling along. In the store the salesman asked me what did I needed today. I told him and I made a comment that their store is only place to go as the Wal-Marts of the world just carry 1 width of very uncomfortable shoes, cheap, but not for me. The other customer, who hobbled said, "you got that right". These are work shoes I’m talking about, steel toes and all. The Right shoes are very important for a machinist, believe me, I felt a little bad for the dude with the problem.

That is about it for this story except one more thing, I jotted down some note to myself on all what had happened because my wife loves to here about things like that. I kind of forgot about it until she spotted my notes on the desk kind of late last night, she asked me what is this? Well I went on to tell her the grand story. We were cracking up, at one point I said when talking abut the man in the store with the foot problem I said, "that guys problem is much worse then mine, but wait a minute, I ain’t got no problem…end

I plan on finishing the machining blog soon, this writing thing takes time that I seem to not have a lot of.

Part 3

After the lathe work was complete I had to Broach a keyway in the bore of the gear. A key is widely used in many applications. To explain; if you wanted a gear to turn you would need to use a motor to turn it. The problem is a round shaft comes out from the motor which then fits through the round bore in the gear, turn it on and the motor shaft would turn but not the gear. The shaft would just spin in the bore. To fix that, on the motor shaft there is a square slot an inch or two long. In the bore you make a square slot the length of the bore. Now you put a "key" which is a square metal piece say 1/4 x 1/4 x 2 inches long, into the slot and it makes it so the shaft can't spin in the bore. In many cases the metal for the key is weak, so if something jams up the key will break and not mess up the motor or the gear. To broach this keyway in the bore, I used a broaching tool. This tool is about 10 inches long, with teeth that are on a taper, as you force the tool thru the bore it keeps cutting deeper. You repeat this until the keyway is the right size. It is a job where you use muscle to force this thing through. Did one, then 4 more. Fun

A day at my job, part 2

　
A DAY AT MY JOB
PART 2

As you may recall I’m in the process of machining a rough part into a finished Gear. The next step is to put it in the chuck on the AXLESON lathe that I’ve been working on. I clamp on the hub, the hub is that 3.5 diameter part that was welded to the flange. To cut the metal we use carbide inserts, these inserts are very hard. They range in size from smaller than a dime to about quarter size, with most being in between that size. Each insert has from 2 to 6 cutting edges. You clamp this insert into a tool holder that you then clamp to the tool post on the lathe. As I told you I’ve 33 years in this trade and I’m still amazed watching those inserts just peal away at that metal. We also use inserts with diamond edges for extremely hard material. I will post some photos of inserts and other things.

Ok, I have delayed starting the lathe and getting to work. The first thing I do is turn the 10.5 diameter to size. To explain this, its back to the cookie, say your cookie is too big so you bite away at the outside edge till you get it to the size you like, so I turn the flange to size, Next I face the front of the part. Another thing, in all machining work the machines use the Cartesian coordinate system, Xyz. On my lathe I use X and Z: Z- is towards the chuck, Z+ is towards the tailstock. This moves the carriage back and forth. X- is towards the part. I move the cross side in and out. All this movement slides on the "ways" of the machine. Back on that tree limb, You cut the down the length of it by moving the carriage in the Z- direction. X- would cut deeper in the part. Now I have the nicely turned the outside diameter to 10.437.

Next I need to faced it to size. These Rough faces may be wobbling quite a bit so with the machine running, I move the tool tip towards the wobbling face until it hits the face, and you know it when it hits the face. Next you move towards yourself using the cross side in the X+ axis to get away from the part. I use a dial indicator that is attached to a magnetic holder. I put it on the way closest to me and zero it out against the carriage. I move Z-, .03 of an inch. Many people’s hair measures .002-. 006 thousands of an inch. So if I move .03 in the Z- direction its like moving the distance of 5-15 hairs. I set the rpm of the machine to 450. I double check things. I engage the automatic feed with a feed rate of around .01; it moves .01 thousands per revolution. That is the low end of the feed rate for roughing.

To finish a part use feed rates of .001-. 004 /for each revolution of the chuck. I have already engaged the feed and the tool tip is now facing off .03. I need to repeat this until I face it to the needed size. I do this operation to four other parts needed for the order. Next with a shinny Face and OD (outside diameter), I change the jaws on the chuck so I can clamp the side I just did in the chuck. The machined area is now running "true" clamped in the chuck. This is very important. To make the 2nd side run true with the first, there can’t be any "run out". When complete the part must be "concentric". Now I face the flange to the finished thickness, I can only face it down to the 3.5 hub. Next I face the hub to the finished length. I turn the OD of the hub to around 3.985 so it "cleans up". Cleans up means the whole face needs to have been cut, or the OD turned till it is completely round.

This entire metal cutting produces a lot of metal chips, they are recycled. So when that cutting tip is cutting the metal, chips are flying. On this job I have been producing a spiral chip that is maybe 2-3 inches long that turns blue as it leaves the surface. Blue because it is extremely hot. The chips vary greatly in size. I had one the other day bounce off my safety glasses. Its real nice when one sticks on you lip, or goes down you shirt. It is good though, that they are turning blue as they are taking the heat of the cut away from the part. You try and keep the part from getting to hot. Remember this is an old manual lathe, on the "CNC" machines that I also program and run, the machining area is enclosed so the coolant is keeping the part cool. On a CNC machine you can make a part with much higher speeds and feeds. One other note, you want chips and not "stringers". If the feed rate is two slow the chips don’t break and stingers can be a big hazard, they can grow to be incredibly long. I’ve witnessed several bad cuts and worse because of them. One thing they can do is create a "rats nest". That’s when the stringer gets caught on the chuck. The chuck is spinning fast. This stringer is one long piece that has been building up in the chip pan. The chuck can yank all that mess up and wrap it around the chuck spinning as fast as the chuck is turning. When that happens, pieces of the stringer are flying all over the place. Try to imagine what that would look like.

I next put in a boring bar, if you recall I rgh. drilled a hole before it was even welded up. So I move the boring bar up close to the face of the part. Make sure my X-axis is set so I don’t cut too much on the first pass. Now I’m using the z-axis automatic feed. I bore the part out to 1.376-1.378. A 1.375 shaft will have to slide through it. That range of 3 thousands of an inch is the "tolerance" I have worked with tolerances of .0004/. 0000. Many machined parts have tolerances of much smaller, I just haven’t run parts with that close of tolerances. I do the other 4 pieces. I am now done with the lathe work.

This is the end of part

A day at my job, part 1

A Day at my job Oct. 16, 2009

Arrived at 7:28, 7:30 is start time and I’m the only one that gets there on time. I’ve always believed in being on time. There are 3 other coworkers with different degrees in machining skills from a few years to me with 33 years experience. I’ve done just about everything that gets done in a machine shop. I needed to keep running the job I already have been working on for several hours’, days before.

What I needed to do at the moment, start up the Lathe. This particular lathe is, ah, 30 years old (?). The name of this lathe, AXELSON, it is a 14X30 which means you can turn up to a 14-inch diameter and a part 30 inches long from the face of the chuck to the tailstock. This is a real beefy machine. You can really hog some metal on it. (Heavy cuts and high feed rates). More info from a nameplate attached to the lathe. It read Mackenzie Machine Tools, Machinery Co. Boston, Mass. This was the person who sold it to someone those many years ago. I wonder if they are still around, hmm

Just to get it straight, imagine if you wanted to make a baseball bat out of a tree limb. To do that you would put it in a lathe and turn it down to size that’s basically what a lathe does, cut round shafts and such.

What I am working on, when finished will be a 10inch in diameter, large tooth Gear. This rather big Gear is for a local Chicken Plant, it drives large conveyers. A week or so ago my boss gave me 5 pieces of 3inch long by 3.5 diameter round stock and also 5 pieces that were cut on a Plasma cutter at a local business that does that. They cut it out of ¾ inch metal plate. Think of the metal as cookie dough and you need to cut 10.5 inch round cookies out of it. That is what this machine does, burn out the shapes we needed. It is really quite amazing to watch those machines run. I had to put these large metal cookies in my lathe and bore a hole to a precise size. Then, if you remember he also gave me 5 pieces of the 3inch by 3.5 inch round stock. In those I had to rough drill a 1inch hole through them and machine the diameter just .003 just undersize of the bore in the plate. So now the "hub" will fit into the flange. Then we sent them to a local welder and he welded the two together. We got them back and now I have to take this rough piece and machine it into a finished Gear

This is the end of Part 1