# Machinists Expect Tighter Tolerenences



## Janderso (Jan 30, 2019)

I learned something about myself today.
I am at work building an 8’ x 30” transmission tear down/build table. You know, the fluid drains to the back and empties into a receptacle.
I am cutting the pieces of 2”X 3” tubing to length.
I wouldn’t be surprised if I was within .010” in length difference between all six legs.
That never would have happened if it wasn’t for this web site and the machinists I have met.
This is just a small representation of the frame of reference change we go through when we improve our skill set.
Every day is a new adventure in the shop.


----------



## 682bear (Jan 31, 2019)

I've heard my dad say many times that good machinists don't make good carpenters... I resemble that remark.

My dad, on the other hand, actually is a good machinist AND  a good carpenter...

-Bear


----------



## Janderso (Jan 31, 2019)

That reminds of my Dad's carpenter days.
He was in sales and pretty much mechanically retarded (sorry Dad).
He would try to fix the lawn mower, get mad, throw a screwdriver and leave. I would come along later and dink with it long enough to figure it out, in my early teen years anyway.
He did build a fence here and there due to our many moves.
Be it split cedar-grape stakes, or to a more contemporary project, every board and post was as perfect to true and level as his trusty ole Stanley could produce. His toe in nails were perfectly spaced and at the same consistent angle.
It was a marvel to watch. he was slow as cold molasses.
I miss him.


----------



## derf (Jan 31, 2019)

I helped a guy build a transmission table years ago. The top was 3/16" thick, and for a drain, we fired up the torch and cut a 2" hole in the center. The heat of the torch warped the top just enough to give it a dip right at the drain hole.


----------



## C-Bag (Jan 31, 2019)

I deal with customers all the time who don't seem to know how to read a tape measure. Inches seem to be inconsequential and the difference between 1/2" and 1/4" seems nit picky. Much less 1/16". So when I try to relay I constantly work in .001 and smaller I get no response. Sometimes I think metrology is just a way of describing a compulsive disorder


----------



## RJSakowski (Jan 31, 2019)

I usually work to .001" for machining, .05" for sheet metal and 1/32" for carpentry.  For cabinetry and joinery, I will measure and layout to 1/32"- and 1/32"+ along with 1/32".  There are of course times when that accuracy isn't required.  The trick is to know when you can loosen the tolerance.

When we did a full kitchen rebuild, we hired a contractor to help with the framing and rough carpentry.  We were calling out dimensions to his helper who was cutting with a miter saw.  The helper would be cutting to nearest 1/4" and I was checking the dimensions when he finished.  When I mentioned that the cuts weren't accurate, the contractor yelled down the his helper "we're working to 1/8" today.  Considering that the pieces in question were studs custom fit to a 100 year old structure, even an accuracy of +/- 1/8th was too loose in my book.


----------



## Tom1948 (Jan 31, 2019)

Worked with a guy once when we was nailing up some 2x 4 's . He started to drive a nail. I said hold it, your a 1/4 inch off. His reply "A 1/4 inch only matters if on the end of your d****. "


----------



## GL (Jan 31, 2019)

Fully agree, machinists try very hard to hit the dimension. Practice when it doesn't matter so you can do it when it does.  As RJ said, you have to know when you can loosen things up.  As I was building my shop, I had to keep reminding myself that this was going to be a shop, not a 40x60 fine woodworking cabinet project.  Things were not going to be seen ever again and a little gap (like 1/16, not 1/4) here and there was really going to be fine.  OCD is when you start sanding the OSB for the walls?


----------



## Bob Korves (Jan 31, 2019)

Machinist apprentice to journeyman mentor:  "Those thousandths sure are small.  There must be about a million of them in an inch."  

I know a guy who manufactured utility trailers.  He hired a young man, showed him how to use the chop saw, and told him to make a bunch of pieces of bar stock 21 13/16" long.  The new hire got busy cutting a whole bunch of pieces, then went to the owner, pointed to the tape measure, and asked "Is this mark here 13/16?"


----------



## Janderso (Feb 1, 2019)

Yes, the old Craftsman style, homes were truly made by Craftsmen. I like the built in cabinetry and crown moldings, square corners etc.
I had the opportunity to watch a neighbor finish his new home when I lived in Lake Tahoe.
His father was doing the finish work. He used an old manual miter box to cut the angles.
Needless to say, it took him a couple weeks and it was perfect!


----------



## Tom1948 (Feb 1, 2019)

Many of the Amish are still good old craftsmen. If there are any in your area you would do good by hiring them.They are good roofers as well.  They still believe in giving an honest days work. That has been my expierience anyhow.


----------



## jwmay (Feb 2, 2019)

682bear said:


> I've heard my dad say many times that good machinists don't make good carpenters... I resemble that remark.


 Does this go the other way too? I was a pretty good carpenter many years ago. But learning machining has been a real effort thus far. 

To the OP, I’d say I haven’t experienced the same at work. Although I have become somewhat of a sounding board for those with questions about metal, a fill in machinist on days when the tool room is off work, and I’ve been able to impress some very experienced old mechanics with my ability to remove broken or stripped socket head cap screws. As far as table legs, I’m still in the “fill the gaps with wire, and put adjustable feet on it” camp. Lol


----------



## C-Bag (Feb 2, 2019)

jwmay said:


> As far as table legs, I’m still in the “fill the gaps with wire, and put adjustable feet on it” camp. Lol



THIS is the crux of the biscuit right there IMHO. In the limited carpentry I've done I've ALWAYS had to adapt to the things that came before. Out of square walls, un even cement etc. Machining in my limited experience is working with more absolute and more controlled tolerances on a much smaller scale. So in the case of table legs I'm also in the wire gaps and adjustable feet camp too because houses and garages just can't hold to that expectation and it makes me crazy to expect it.


----------



## Forty Niner (Feb 2, 2019)

I have the machinist disease for precision.  
I was working with a neighbor/friend one time building our boat dock.  One measuring, one cutting.  I took a measurement and called out 67 and thirteen sixteenths, ... and leave the line.     He was a carpenter and that drove him crazy.  He cursed me and informed me that we were building a boat dock and not a spacecraft.


----------



## 682bear (Feb 2, 2019)

jwmay said:


> Does this go the other way too? I was a pretty good carpenter many years ago. But learning machining has been a real effort thus far.



I think my dad was trying to make me feel better about my incompetence as a carpenter. We built my house ourselves... mostly... we hired out the HVAC, the brickwork, and the roofing. Me and dad did all the framing, wiring, plumbing, sheetrock, etc.

I'm still a lousy carpenter... but I'm not afraid to try when I need to.

-Bear


----------



## Littlebriar (Feb 3, 2019)

I drive my son crazy. We often renovate rental units together. He'll grab 4 2x4's, stack them up and wack them all with a chop saw in one hit. I'll set up a stop on the fence and cut each one individually and they will all be precisely the same length. He works a bit faster than me most of the time. If something is off a bit, it drives me crazy and I can't help but look at it even months later. I'm sure nobody else notices. We had to hang a bunch of doors once and we had a competition to see who could do it faster. I used a different technique but that day I kept up with him. I like the precision of fine furniture building and metal work. I think it's my engineering training.


----------



## Nogoingback (Feb 8, 2019)

Interesting that you brought this up.  A couple of weeks ago I spent 3 days helping a friend work on his barn.
He needed to jack up and shim a wall, rebuild some stairs etc.  It became a joke between us that he was always
trying to knock stuff out faster and I was always slowing us down to do things more accurately.  He told me I was
trying to do it to thousandths.  But, he was happy with the results...


----------



## Bentley18 (Feb 8, 2019)

I make industrial cutting tools.  For 23 years I made special cutting tools for Pratt, Pratt Canada, Allison, Rolls, and others and always worked to a .001" or less. So now when I make anything, I always shoot for perfection which doesn't exist.


----------



## westerner (Feb 8, 2019)

C-Bag said:


> THIS is the crux of the biscuit right there IMHO. In the limited carpentry I've done I've ALWAYS had to adapt to the things that came before. Out of square walls, un even cement etc. Machining in my limited experience is working with more absolute and more controlled tolerances on a much smaller scale. So in the case of table legs I'm also in the wire gaps and adjustable feet camp too because houses and garages just can't hold to that expectation and it makes me crazy to expect it.


Wow- "The crux of the biscuit"! I have been quoting that phrase for years. My brother was the Zappa fan, but I surely did appreciate the humor, and the intellect. That said- I worked in the construction trades for years, and it taught me many things. The lesson that probably sticks most tenaciously is this- "You GOTTA work within the tolerances required by the person cutting the check." If you work to YOUR tolerances, you either make little dough/hr, or you don't work there long at all. 
The same applies across all trades, really. The beauty of all this comes when YOU are the one "cutting the check", so to speak. I really enjoy the work I do, building things FOR ME. Myself and I frequently discuss quality control, and the debate can get lively. But the "check" always clears


----------



## Firstram (Feb 8, 2019)

I've always noticed, a carpenter makes a better welder than a welder makes a carpenter.


----------



## brino (Feb 8, 2019)

....and how about the framing helpers that when measuring call out "16 inches, two big ones and three little ones".
(presumably for 1/2's and 1/4's, but maybe for 1/4's and 1/8's, or perhaps for 1/8's and 1/16's...or maybe....)

Why bother even having a tape measure if you won't use it?!?!?!
Might as well just say "as long as my fore-arm" then hammer it in and nail it tight.
Frustrating!

-brino


----------



## C-Bag (Feb 9, 2019)

westerner said:


> Wow- "The crux of the biscuit"! I have been quoting that phrase for years. My brother was the Zappa fan, but I surely did appreciate the humor, and the intellect. That said- I worked in the construction trades for years, and it taught me many things. The lesson that probably sticks most tenaciously is this- "You GOTTA work within the tolerances required by the person cutting the check." If you work to YOUR tolerances, you either make little dough/hr, or you don't work there long at all.
> The same applies across all trades, really. The beauty of all this comes when YOU are the one "cutting the check", so to speak. I really enjoy the work I do, building things FOR ME. Myself and I frequently discuss quality control, and the debate can get lively. But the "check" always clears


Time and again in different jobs I was told to work to the closest tolerances and then criticized for being slow. My response was always do want it right or do you want it fast? The good thing about being the one who writes the check is you don't HAVE to find something to criticize. They put me on the crew because there was no tolerances and then I'd have to get in somebody's face, boss or fellow crew when it took more time. But it's like a golf shot. Just a little off at the beginning gets you WAY into the rough by the end.

We were laying out a fruit sizer that was 10' wide and 120' long. It had 3 huge chains that is the heart of the machine and their chain guides needed be laid out accurately in the bed of the frame of the machine. I didn't know it at time but they put me charge because the rails always looked like drunks had installed them. The crew would look at the prints and carefully cut a piece of 2"x2" tube jig to exactly what the print said and then lay tube on the header, slide the rails up against it. Then whack it up against the jig tube and tighten down the rail. The problem now was getting the jig out. So they just whacked out and went on. Never having the time to see extracting the jig just pushed the rail out of alignment. 

So when I got the job to lay out the rails they handed me the jig and on the first rail I realized I could not make this work. I tried cutting the ends so just one edge on each end touched and it was better. But you still had to whack it free and that sometimes took a bit. I ended up taking the tube and cutting it and putting a hinge in the middle so it would freely lift out afterwards. I got about 10 headers down and all the sudden I was swarmed by bosses alarmed I wasn't beating furiously on the setup. They looked, they measured, they looked down my done rails and told the crew leadman to keep that jig. It dissapeared after we got done with the machine. That same leadman laid out the next machine with a solid tube jig. Call it historical engineering.


----------



## jwmay (Feb 9, 2019)

brino said:


> ..and how about the framing helpers that when measuring call out "16 inches, two big ones and three little ones".


 
I was a carpenter in the Army. On my third deployment we were sent ahead of our tools, but had work on day one ofc. My family was anxious to send us care packages, and wanted to know what I needed. I sent back, “I need ten dummy tapes, and pack of pencils, and a hammer.” 

For those that don’t know: A dummy tape is a tape measure that’s numbered to sixteenths.


----------



## westerner (Feb 9, 2019)

C-Bag said:


> That same leadman laid out the next machine with a solid tube jig.


Yup. There you go. "you can lead a man to knowledge, but you can't make him think".


----------

