Although possessing [an education] does not guarantee or indicate the level of [skills] & [experience] at all.

Very true.
I've seen the limitations of newly-minted engineers reveal themself numerous times in my 53+ years as an engineer.
Education is but the first step in developing a collection of skills through a lifetime of experience.
If I knew back then what I know now, the road of life would have been much smoother.

 

But in many ways, it is not the full story,!
Per my erudite quote by Einstein below.

 

Very true.
I've seen the limitations of newly-minted engineers reveal themself numerous times in my 53+ years as an engineer.
Education is but the first step in developing a collection of skills through a lifetime of experience.
If I knew back then what I know now, the road of life would have been much smoother.

That is why ALSO mentioned the many decades of experience. And I neglected to mention the BALDOR motor application seminars. The fact is that there are quite a few rather experienced folks found posting when needed. So it is very seldom just one source.

 

If you were wondering, I have a Master's degree in Electrical Engineering and a Bachelor's in general engineering.

How does that compare to your skills, education and experience?

It likely exceeds my level of on-paper qualifications. I studied electronics and telecommunications full time and achieved (UK qualifications) my HNC and HND, this equates approximately to the first two years of a bachelor of science degree. That education also included a decent amount of industrial electronics including health and safety in a factory setting and all varieties of AC and DC motors, single phase and three phase and so on, though I've forgotten much of it.

I also studied for a year and gained an HNC in Computer Aided Engineering and had stuff published in several electronics journals of the day including Electronics Today International and Wireless World in the late 70s and early 80s.

Regrettably, I never did work in electronics professionally (apart from a few months at Sinclair Radionics) and ended up making my career in software.

But as I stated, my opinion on opting for a tool with braking already included, was not a comment on anyone's skills or experience or competence, it was just my opinion and reflects my concern for safety and robustness with power tools, so whatever you do I hope a safe and robust outcome is achieved.

 

We are all strangers on the internet so all my various degrees from UGoogle are as valid as anyone else's dusty old papers.

With the authority vested in me by my exceeding intellect and overwhelmingly vast body of knowledge in all things mechanical and electrical, I declare that all you need to do is drill a hole through the arbor, replace the existing nut with a castle nut, and put a cotter pin through it. Then there is no more safety concern, no more risk of damage, and no more reason to compare peepee sizes or land any more blows on the dead horse.

You're welcome.

(Exists to imaginary applause)

 

I also studied for a year and gained an HNC in Computer Aided Engineering and had stuff published in several electronics journals of the day including Electronics Today International and Wireless World in the late 70s and early 80s.

Interesting. As part of my Bachelor's in General Engineering I had a semester course in machine tools where we all became reasonably competent in the use of the metal lathe, vertical mill, broaching machine, drill press, horizontal mill, surface grinder, and a few more I can't remember. In 1980, I took on a job as Coordinator of Computer-Aided Design at our technical college, where I developed the curriculum and taught the classes on computer-aided drafting using a $250K ComputerVision system. The CAD classes were integrated in with the computer-aided manufacturing CAM courses at the college. It was an interesting diversion from electrical engineering.

 

Since every now and then someone responds to the question, here's mine:

Across many military contractors and medical tech companies, a very common rule of thumb or explicit requirement, almost to the point of an industry standard, is a 100% operating voltage margin on electrolytic caps. That is, use a 25 V cap in a 12 V circuit. Same for voltage and current ratings of transistors, power ratings of resistors, etc. This has an enormous impact on long-term reliability. Of course it also has a big impact on cost, but life is choice.

You can get close to this with a simple series-parallel arrangement.

Note that some specialty parts, such as motor-start capacitors and X- and Y-rated capacitors in power line filters are designed to run continuously at or near their ratings. General-purpose electrolytics will run just fine right at their voltage rating, but at that voltage their MTBF might be as short as what is stated on the datasheet, sometimes only 1000 hours.

ak

 

Interesting. As part of my Bachelor's in General Engineering I had a semester course in machine tools where we all became reasonably competent in the use of the metal lathe, vertical mill, broaching machine, drill press, horizontal mill, surface grinder, and a few more I can't remember. In 1980, I took on a job as Coordinator of Computer-Aided Design at our technical college, where I developed the curriculum and taught the classes on computer-aided drafting using a $250K ComputerVision system. The CAD classes were integrated in with the computer-aided manufacturing CAM courses at the college. It was an interesting diversion from electrical engineering.

Well I'll admit you do seem very well positioned to embark on such a task. But why? interest? costs? its likely you'd do a superb job of this, but better than a commercial version that complies with safety standards, regulations, has been independently certified?

If I understand this so far, the motive is to increase the safety of the tool, reduce the risk arising from running despite being shut off. Well, increasing safety is more than just adapting the machine's design, that's all I'm saying, perhaps I'm just being an old fuss pot though!

 

Interesting. As part of my Bachelor's in General Engineering I had a semester course in machine tools where we all became reasonably competent in the use of the metal lathe, vertical mill, broaching machine, drill press, horizontal mill, surface grinder, and a few more I can't remember. In 1980, I took on a job as Coordinator of Computer-Aided Design at our technical college, where I developed the curriculum and taught the classes on computer-aided drafting using a $250K ComputerVision system. The CAD classes were integrated in with the computer-aided manufacturing CAM courses at the college. It was an interesting diversion from electrical engineering.

The last 30yrs-40yrs of my working career was involved with upgrading, designing and retro-fitting CNC Machinery of all kinds.
The systems I used for this were mainly Mitsubishi controls, also some PC slot based versions, designed using a plug in Galil motion card.
I still receive emails from those that have picked up machines from different sources which often posses older CNC operating systems, and have failed to download and keep a copy of the system parameters.
This often means that if no copy can be found, the machine reverts to a chunk of iron sitting on the shop floor.

 

(Exists to imaginary applause)

So, you skipped the UGoogle degree in spelling - ?

Or did you mean that you exist *for* imaginary applause? That, I'll believe.

ak

 

So, you skipped the UGoogle degree in spelling - ?
Or did you mean that you exist *for* imaginary applause?

I believe Mr. Strantor meant it to be a play-on-words for a stage direction like, "Exits stage left to imaginary applause" with an accidental 's' typed in.

 

So, you skipped the UGoogle degree in spelling - ?

Or did you mean that you exist *for* imaginary applause? That, I'll believe.

ak

Doh!
Every time I try to be clever...
Yes, exits.

 

Could you share a picture of said bandsaw? and perhaps the motor too?

 

Well I'll admit you do seem very well positioned to embark on such a task. But why? interest? costs? its likely you'd do a superb job of this, but better than a commercial version that complies with safety standards, regulations, has been independently certified?

If I understand this so far, the motive is to increase the safety of the tool, reduce the risk arising from running despite being shut off. Well, increasing safety is more than just adapting the machine's design, that's all I'm saying, perhaps I'm just being an old fuss pot though!

I find it amazing and hard to understand the intense fear of making any change in a machine, especially a well defined addition that will reduce a potential hazard. What I see is a religious level belief that none except the original designers are able to design and implement anything worth anything, and that any such modifications will invariably result in some disaster.
Consider that in much of product design the primary mandate is minimize the expense of production so as to maximize profit. This usually means aiming to just barely satisfy the requirements and nothing more, unless it increases profit or is demanded by the laws. That would include leaving out any quick-stop circuit because it costs extra. So why the blind faith that the original design is sacred????

 

Could you share a picture of said bandsaw? and perhaps the motor too?

My brother is up in Minneapolis so the saw is about 5 hours away.
So, I can only share a stock photo image (click to enlarge).
I'm pretty sure it's this Grizzly 17" 2HP.

 

I find it amazing and hard to understand the intense fear of making any change in a machine, especially a well defined addition that will reduce a potential hazard. What I see is a religious level belief that none except the original designers are able to design and implement anything worth anything, and that any such modifications will invariably result in some disaster.
Consider that in much of product design the primary mandate is minimize the expense of production so as to maximize profit. This usually means aiming to just barely satisfy the requirements and nothing more, unless it increases profit or is demanded by the laws. That would include leaving out any quick-stop circuit because it costs extra. So why the blind faith that the original design is sacred????

Let me respond by asking some questions, how did you establish that the proposed modification to the bandsaw is a "well defined addition"? (it might be, but we've seen no picture, no diagrams). If you haven't yet done that then how do you intend to do it?

Next question, testing...how does one test that the modified system is safe? what kinds of tests should we do, what kind of analysis on the results should we do? how many tests should we do? what should the MTBF be? how can we establish what it is?

Next question, failure...what kinds of failure can we envisage? what varieties of electrical failure failure could arise? what varieties of mechanical failure could arise? what could happen to a user if any of these were to arise? what's the worst case kind of failure we can reasonably envisage?

Now, you say "the primary mandate is minimize the expense of production" well how did you establish that? you don't know who manufactured the bandsaw even! Anyway what is a "primary mandate"? The manufacturer likely wants to remain in business and want to minimize risk of costly lawsuits so safety will likely be very high on their list of objectives - at least if manufactured here or a place where legal recourse is a possibility.

I'd argue that all design, all engineering be it mechanical or electrical is an exercise in compromise, there are multiple, possibly conflicting goals and the job of management, leadership is to navigate those waters.

So having said all that I suspect that the manufacturer is very likely (not necessarily) the most well informed party here, I can't glibly assume that I alone can "make a better X" than a power tool company unless I am or have lots of personal experience working in, a power tool company.

Now of course the OP's main concern IS safety, he wants to improve the machine's safety, make it safer, I understand that. That's why I am taking the position I am, it is critical feedback, questioning assumptions, asking awkward questions that can help to achieve quality, no intense fear here my friend just unemotional hard cold logic.

 

My brother is up in Minneapolis so the saw is about 5 hours away.
So, I can only share a stock photo image (click to enlarge).
I'm pretty sure it's this Grizzly 17" 2HP.
View attachment 293676

Man, I want one!

 

Read:

https://kpic.com/news/local/man-survives-going-through-wood-chipper-11-13-2015

"...When something got stuck inside the machine, he went in thinking everything was turned off - just like they practice - to get the object..."

i.e. in this case, a user could be forgiven for thinking the machine "has a braking system", so will definitely have a safe blade after ten seconds... etc etc etc...

Part of the reason I even take this view is my own profession - software design.

1. What if the user didn't press X though?
2. What if the network is up but goes down after event W?
3. But if a user says "Yes" to the update and the network is down, the system could crash and self-update later unexpectedly.
4. There's no way to guarantee though that the user doesn't have two versions installed and so when they...
5. Just to be safe, it should always verify if the settings have been changed but not yet used, we can do that check by...

and so on and so forth, this comes up (or should) all the time in software design, what-if...

 

In an effort to put this string out of its misery (and to move on to new topics to argue about) here is a summary what has been learned so far:

1. The overhead of an electrolytic is NONE. In typical applications the rated voltage of the cap should be selected to be 150% of the circuit voltage. In critical applications the rated voltage should be selected to be 200% of the circuit voltage.
   That being said, electrolytics have a surge voltage rating which allows for short-duration over-voltage events. This is listed on data sheets as allowing a spike of up to 15% above the listed voltage for caps rated at 250V or less. Each surge should be less than 60 seconds in duration with a rest period between surges of >5 minutes.
2. The consensus appears to be that the OP should be using 250V caps in his 120-VAC circuit, which would give him 80V of overhead, but the OP is a cheap bastard and wants to get by without spending any money on this, since the OP already has forty-seven new 150V 6600 µF capacitors just lying around collecting dust.
3. So, the OP will need to drop the operating voltage of the circuit from 170-VDC down to under 150-VDC to use the caps he already has. To accomplish this, the OP mounted thirty-two cheap 1N4007 diodes in series on a perf board to drop the charging voltage from 170V down to around 145V. (clever lad)
4. Now that the original issue had been solved, the conversation then shifted to argue about totally unrelated things, as inevitably happens with every thread longer than five posts.
5. First, a formal education will get you started in a career, but experience is what will successfully carry you through to the end.
6. Second, our dear friends from across the Big Pond in the UK are concerned about us modifying existing designs, but this is only because they care deeply for our safety and well being, especially in this era where the perceptions of many in the UK are probably that every man, woman and child in the US rides a horse to work or school, and carries around a holstered Colt 45 revolver.
7. Since we're on that topic, my next-door neighbor told me last week that Texas governor Greg Abbot is about to sign legislation that makes it so that if you do not want to open-carry a weapon in Texas, you will need to obtain a permit authorizing you not to carry a weapon (with no religious exceptions.) Makes sense to me. Hard to argue with that.
8. Next, if you have something heavy that spins very fast on an arbor held on with a nut, it's not a bad idea to cross-drill the arbor shaft and use a castellated nut with a cotter pin, just to be safe.
9. And finally, although the OP thinks that the new artificial intelligence applications like ChatGPT are the greatest thing to come around since sliced bread, there are some out there that are questioning the OP's wisdom and critical-thinking skills, and are urging the OP to immediately seek Professional Help.

 

As someone who lives in Texas, I approve and appreciate your comment about our “great dear leader” Greg Abbot.