Close enough

[collinb]

These are the measurements on the ends of the fifth cut for my new sled. That's 0.0015 before / 4. I can live with it.

Sent from my MotoE2(4G-LTE) using Tapatalk

[collinb]

one thing that allowed me to adjust it so close was keeping the math simple by keeping the assembly simple.  One of the confusions people seem to have is calculating the necessary offset based on differing distances from the pivot screw (the first one, fixed) to the adjusting screw (the second).  My simplification was this: Since I'm going to need two screws to the long side anyway, I'll begin with one not at the outside but toward the inside, at the same distance from the cut as the first.  That makes things very simple. 

As a result divide is simplified. First the fifth cut is divided by 4.  Then, using an equidistant point for the second screw into the fence, the number is multiplied by 2.  Then I just attach another outside screw on the long side and it's done.

[Brendon_t]

I failed algebra 3 times, now I feel like a failure at life..

[collinb]

table saw

7 minutes ago, Mike. said:

Is this a tablesaw or planer sled?

 

[collinb]

55 minutes ago, Mike. said:

It looks like you are measuring the thickness of the board.  Maybe I am missing something.  How does measuring the thickness tell you if your cross cut is square? 

It's the width of the final cut, the difference between the two ends, which is x - y.  The closer to zero the closer to square.  But 5 cuts are done instead of just one to allow for a board which is not square to begin with.  The fifth cut is actually the 4th cut off reference cut, with the first being the cut which pre-sets the first angle, or reference, for the next four.  By using this approach, per the videos mentioned often here, the fifth cut delta is 4x the difference.  It's easier to measure .01 than it is .0025.  The additional cuts multiply the precision thus allowing more accurate adjustments.  It's just geometry.

Delta  just means "difference".  Hence the Greek letter, the little triangle thingie.

[collinb]

24 minutes ago, Mike. said:

Thanks, I know what delta is.  I took university calculus.  The image must be deceiving [ :-) ] because it looks like you are measuring the thickness of your board, not the width.  

Didn't know that. Offense not intended. I was considering other readers.

It's the measurement of the width of what was cut off the edge of the piece of plywood.  The thickness measure would have gone the other direction, parallel to the plys.

 

[Coop]

Yeah, I did too Collin! That's pretty darn close on that sled! Good job!

And I'm still trying to cope with my grandkids intermediate math

[Brendon_t]

11 minutes ago, K Cooper said:

Yeah, I did too Collin! That's pretty darn close on that sled! Good job!

And I'm still trying to cope with my grandkids intermediate math

If it's common core, don't even try to understand it. They effectively re wrote the rules of math..

[Cliff]

2 hours ago, Brendon_t said:

If it's common core, don't even try to understand it. They effectively re wrote the rules of math..

Naa. What they did is finally get closer to how I do math in my head and start teaching it to kids. 

 

[Brendon_t]

14 minutes ago, Cliff said:

Naa. What they did is finally get closer to how I do math in my head and start teaching it to kids. 

 

Then I'll blame you for then teaching my kids that division is 8 goats divided by 3 blue rocks equals friendship. 

[wtnhighlander]

If they are calling it "mathS" (plural), you are screwed.

[Coop]

2 hours ago, Cliff said:

Naa. What they did is finally get closer to how I do math in my head and start teaching it to kids. 

 

Math in your head is only divisible by 2 and should stop there?

[wdwerker]

Math is why I have a very good calculator app on my phone and iPad  ! 

Calc Pro HD if anyone needs one. It have far more modes than I will ever need. Excellent conversion calculator, length, weight, speed, currencies, temperature , you name it and you can convert to whatever scales are used . All sorts of scientific, financial,statistics......

[collinb]

Get a slide rule. No batteries. 2 digits accuracy. Faster than a calculator for most common operations.

Sent from my MotoE2(4G-LTE) using Tapatalk

[Cliff]

10 hours ago, Brendon_t said:

Then I'll blame you for then teaching my kids that division is 8 goats divided by 3 blue rocks equals friendship. 

Wait this sounds like it might be beyond common core. But I am a fan of goats, so I'm down with this.

 

8 hours ago, K Cooper said:

Math in your head is only divisible by 2 and should stop there?

Think of it this way, anything that is divisible by any multiple of 2 is also divisible by 2, just multiple times. Doing math in your head is all about breaking the problem down into small pieces, solving them then recombining.

 

5 hours ago, wdwerker said:

Math is why I have a very good calculator app on my phone and iPad  ! 

Calc Pro HD if anyone needs one. It have far more modes than I will ever need. Excellent conversion calculator, length, weight, speed, currencies, temperature , you name it and you can convert to whatever scales are used . All sorts of scientific, financial,statistics......

 

I do my best to never use calculators. I feel like math is a skill, and if you ignore any skill, you get worse at it. I think that's why so many people are bad at math. It's not that they don't understand it, it's just that they don't use it. And that's fine, because doing math in your head really does nothing more than save a few seconds of time in most situations. It's not terribly important.

 

[Cliff]

3 minutes ago, Mike. said:

politics aside, I am actually a fan of commom core math.  Like cliff said it is really about taking problems and breaking them down to smaller components.  

My bigger frustrations with my kids' math is 1) the number of typos on a typical publisher worksheet and 2) incomplete or incomprensible instructions.  The publishers are in a rush to get these things published (and appease Texas and California) so they tend to be sloppy.  

The better teachers make up their own homework assignments rather than rely on publisher worksheets.  

But I am the wrong person to ask  While most parents around me are shuffling their kids between travel basketball and hockey on saturday, I send mine to extra math classes.  My kids play sports too but academics are a much higher priority. 

Good for you man. I'm not a kid person, but I can appreciate it when parents spend the extra time educating their kids. Yeah they will be jealous of their friends, but in 20 years their friends will be jealous of them, so it it all works out.

[Chestnut]

I don't know why people struggle with math so much, It's way easier than writing and grammer and spelling. What do i know i got an engineering degree so i could avoid languages altogether.

For math I'm all for pushing what makes sense to you. If just doing it in your head works go for it. If common core is your thing go for that as well. my only complaint about the school system is and always will be that they are stifling creative thinking and trying to fit kids into boxes. At least that is how it seemed to me 15 years ago and still now.

[Cliff]

8 minutes ago, Chestnut said:

I don't know why people struggle with math so much, It's way easier than writing and grammer and spelling. What do i know i got an engineering degree so i could avoid languages altogether.

For math I'm all for pushing what makes sense to you. If just doing it in your head works go for it. If common core is your thing go for that as well. my only complaint about the school system is and always will be that they are stifling creative thinking and trying to fit kids into boxes. At least that is how it seemed to me 15 years ago and still now.

I agree. And whats more, they don't teach kids anything. They teach them how to pass tests. That's about it. they also teach nothing but fantasy. You can point out almost anything you learned in school and turns out it's wrong. But those same things are still being taught. I send a kid to school and when he came home to tell me about the hero Christopher Columbus and how he discovered America - I'd sit him down and be like "listen, all of that is a lie. Sorry, tell your teacher they are dumb."

 

[Chestnut]

2 minutes ago, Mike. said:

There is a lot to be said for that.  Right now one of the trends is integrating reading into all subjects.  So math and science are very heavy on word problems and writing essay responses "explaining" an answer ("I feel like 2+2 = 4 because i have two best friends and if I had two more than I'd have 4 best friends even though a superlative implies 1") 

The end result:   Kids who struggle verbally now hate math and science as well, even if they have an aptitude for it.  

Woah Woah Woah 2+2+5 (for large values of 2) if you want me to prove it i can.

2 minutes ago, Cliff said:

I agree. And whats more, they don't teach kids anything. They teach them how to pass tests. That's about it. they also teach nothing but fantasy. You can point out almost anything you learned in school and turns out it's wrong. But those same things are still being taught. I send a kid to school and when he came home to tell me about the hero Christopher Columbus and how he discovered America - I'd sit him down and be like "listen, all of that is a lie. Sorry, tell your teacher they are dumb."

 

Oh teachers are probably going to hate me as a parent. I'll end up teaching my kids that a calculator is always within reach so do what ever you need to pass and learn the more important math like geometry, trig, and calculus.

[Janello]

Wait.....having known all this math is great for building this sled but common sense is more important. You used a big ugly fuzzy edged void ridden piece of plywood as your control. MDF with smooth edges would have given you a more accurate reading. You can't split hairs with a dull axe.

I'm sure your sled is fine, my point is... A calculator and some common sense usually trumps the brainiac that can't see the forest through the trees.

[collinb]

1 hour ago, Chestnut said:

Woah Woah Woah 2+2+5 (for large values of 2) if you want me to prove it i can.

Oh teachers are probably going to hate me as a parent. I'll end up teaching my kids that a calculator is always within reach so do what ever you need to pass and learn the more important math like geometry, trig, and calculus.

<rant on>The biggest educational problem is not CC.  Though CC is a problem (b/c it nationalizes curricula) the whole Dewey/Mann approach has lead to our current high rate of illiteracy. Being cognizant rather than analytical, imaginative rather than creative, age-appropriate rather than tailored, amoral rather than moral, consolidated vs community, et al.  This is why home schooling is not only growing but is far more successful. The problem is not the teachers. It's the educational philosophy they are saddled with.<rant off>

[Tpt life]

3 hours ago, Mike. said:

politics aside, I am actually a fan of commom core math.  Like cliff said it is really about taking problems and breaking them down to smaller components.  

My bigger frustrations with my kids' math is 1) the number of typos on a typical publisher worksheet and 2) incomplete or incomprensible instructions.  The publishers are in a rush to get these things published (and appease Texas and California) so they tend to be sloppy.  

The better teachers make up their own homework assignments rather than rely on publisher worksheets.  

But I am the wrong person to ask  While most parents around me are shuffling their kids between travel basketball and hockey on saturday, I send mine to extra math classes.  My kids play sports too but academics are a much higher priority. 

You are NOT in error here at all. Worksheets are not the differentiation expected today. The sheets come very dependent on the student's understanding in the lesson. If your child didn't? The math instruction is not occurring the way it was when I took it. As an educator the best thing I can tell you is to never stop talking to your kids' teachers. The teachers may not like it. Who cares. Your kids are worth it. The worst thing you can do is assume that the teacher is always right or is covering everything in their limited time. The fact that you know what is on the worksheets does speak to your character. Keep it up. 

 

3 hours ago, Chestnut said:

Woah Woah Woah 2+2+5 (for large values of 2) if you want me to prove it i can.

Oh teachers are probably going to hate me as a parent. I'll end up teaching my kids that a calculator is always within reach so do what ever you need to pass and learn the more important math like geometry, trig, and calculus.

Testing now has calculator portions and non. The mood is shifting to account for tech permeation. 

[Cliff]

2 hours ago, Janello said:

 A calculator and some common sense usually trumps the brainiac that can't see the forest through the trees.

I feel that statement is somewhat incorrect. For one thing, anything beats anyone that "can't see the forest through the trees." Doesn't have to be a braniac. Using plywood that is jacked may cause a problem no matter how you arrive at your calculations.

Point is, dumb people have common sense, smart people have common sense and sometimes, both don't have it. Sometimes people just flake out for a day and do stupid things, other times common sense is a learned response, right? For instance, if you don't know all the details of a situation, you make a decision based on what you got. In fact, "common sense" is only common if you are armed with knowledge. It's common sense to not run out in front of a car, but that's only because we have knowledge that cars are dangerous, moving fast, weigh a lot, not made of jello. Without those critical data points, we can't make an informed decision.

And I'm not taking what you said as an insult towards myself or anything like that - Just that "braniac" in that sentence is pretty narrow. I mean, remove "calculator" and "braniac" and the sentence is entirely true. I don't feel either term has anything to do with common sense.

[Chestnut]

2 minutes ago, Cliff said:

I feel that statement is somewhat incorrect. For one thing, anything beats anyone that "can't see the forest through the trees." Doesn't have to be a braniac. Using plywood that is jacked may cause a problem no matter how you arrive at your calculations.

Point is, dumb people have common sense, smart people have common sense and sometimes, both don't have it. Sometimes people just flake out for a day and do stupid things, other times common sense is a learned response, right? For instance, if you don't know all the details of a situation, you make a decision based on what you got. In fact, "common sense" is only common if you are armed with knowledge. It's common sense to not run out in front of a car, but that's only because we have knowledge that cars are dangerous, moving fast, weigh a lot, not made of jello. Without those critical data points, we can't make an informed decision.

And I'm not taking what you said as an insult towards myself or anything like that - Just that "braniac" in that sentence is pretty narrow. I mean, remove "calculator" and "braniac" and the sentence is entirely true. I don't feel either term has anything to do with common sense.

There is a lot that comes back to the definition of intelligent or brainiac. I feel that personally can vary from person to person. There are different levels of intelligence and different types. It's also too difficult to tell which one is better. Would you rather be the master of your field or a jack of all trades? A master can defiantly figure out the fine details of his field but can't apply that knowledge outside it, where as a jack of all trades can apply his limited knowledge in each field across off the fields he knows. Both are intelligent brainiacs but one gets lost in the forest. There are also the people that spent their life avoiding learning and get lost in the forest not knowing if it's daylight or nighttime.

I realize i said a lot of the same thing that you said but i often find myself calling the master of one a dumb smart person. I know a few people that fall into this category.

[Janello]

47 minutes ago, Cliff said:

I mean, remove "calculator" and "braniac" and the sentence is entirely true

But...then it's not even a sentence. lol

I guess I should replace braniac with "pompous ass know it all" and calculator with knowing how to find information rather than thinking you know everything. 

My buddy tells me stories about the highly edjucated engineers where he works that want to rip a whole machine apart before checking the gas valve. I'm not implying anyone here is a pompous ass, just saying I'd rather be the guy that checks the gas valve first and then pulls out a manual if I have to.