Shopsmith Forums

A few years ago, I designed a 1 hp motor drive that was integrated onto the motor itself. To avoid derating the continuous motor power, the electronics were designed to operate at an ambient temperature of 100C -- the boiling point of water. Because that's how hot the motor case runs at full rated output power.

And because the whole shebang had to be operable in extreme environmental conditions, including complete submersion in water, there was zero forced-air cooling. So the air temperature in the sealed electronics enclosure (which was about the size if a large coffee mug) ran even hotter. Yet all of the silicon junctions operated comfortably within their recommended operating temperatures. The high-temperature bus capacitors needed for the application cost more than the garden variety, but were still a standard item. So Ed is entirely correct in saying that just because operating temperatures seem high to you, it doesn't necessarily mean that there is anything wrong with the design.

Someone mentioned the rule of thumb about the lifespan of electronics doubling with each 10C reduction in operating temperature. This is also true, but applies primarily to the lifetime of insulation. In this case, the insulation of concern would be the insulating varnish on the motor windings (magnet wire), and especially between the film layers in the electrolytic capacitors. An average-quality electrolytic capacitor is typically rated for 2000 hours of operation at max rated temperature, and an expensive one for 5000 hours. So here, it is clearly desirable to keep the operating temperature as low as practical.

Without having access to all the design details that Ed mentions, I really can't second-guess Shopsmith's cooling design. Except to say that the presence of silver-colored finned heatsinks inside the headstock raises questions in my mind. That usually means that either forced-air or unimpeded convection-air cooling was the design intent. If radiant heat transfer (to the headstock housing) was intended, they should be black-anodized. My overall hunch is the same as most here - that the high-speed performance of the PP headstock could be improved considerably by revisiting the cooling design.

We all know that electronics doesn't like excessive heat. So, I have to ask, why do we want electronics in every device we own when it doesn't add any real improvement, and usually causes lower reliability than a simple mechanical device?
I learned that years ago when I bought my current house. It had an almost new Amana kitchen range with the fancy electronic controls. The oven was not usable because once it heated up, the electronics went spastic and shut down with lots of beeps and blinking lights. The range was a year out of warranty, and replacing the electronic control board would cost as much as a new non-electronic range. And, research on the internet told me that this was a common problem once the range reached 2 years of age, so replacing the board would likely just delay the problem a short time and return.
I took the smart way out. I junked the Amana range and bought a cheap Whirlpool range with mechanical controls. This one is now over 10 years old with no hint of any kind of problem.
I have had similar issues with other devices that had unnecessary electronics in them. Adding the electronics simply took away the simple reliability of the device.
The old adage, KISS (keep it simple, stupid) makes sense. You will never get any error message from your hammer, and the batteries never go dead.

Buckeye Dennis makes the most sense and I believe he hit the nail on the head. The biggest clue to this is the heat sink that is used. The design, shape and placement speaks volumes to what is trying to be accomplished.
My opinion.

garys wrote:We all know that electronics doesn't like excessive heat. So, I have to ask, why do we want electronics in every device we own when it doesn't add any real improvement, and usually causes lower reliability than a simple mechanical device?
I learned that years ago when I bought my current house. It had an almost new Amana kitchen range with the fancy electronic controls. The oven was not usable because once it heated up, the electronics went spastic and shut down with lots of beeps and blinking lights. The range was a year out of warranty, and replacing the electronic control board would cost as much as a new non-electronic range. And, research on the internet told me that this was a common problem once the range reached 2 years of age, so replacing the board would likely just delay the problem a short time and return.
I took the smart way out. I junked the Amana range and bought a cheap Whirlpool range with mechanical controls. This one is now over 10 years old with no hint of any kind of problem.
I have had similar issues with other devices that had unnecessary electronics in them. Adding the electronics simply took away the simple reliability of the device.
The old adage, KISS (keep it simple, stupid) makes sense. You will never get any error message from your hammer, and the batteries never go dead.

Electronics are not inherently unreliable. The problem is that the component technology keeps changing/improving so fast that designers don't always know where the gotchas are. But a properly designed circuit, with all components operating within their rated stress levels, obviously has no moving parts, and will last a long, long, time. Obsolesence will generally come before wear-out.

Infant mortality in electronics is the result of either a flawed component or a flawed design.

All this 'design' criteria is correct, but the objective of the SS DVR design was to get it all in the 50 year old headstock design(back ward compatibility).

They succeeded it that quite well.

Perhaps the top speed was a poor goal.

Perhaps the heat issues were not properly addressed.

Perhaps because we simply do not know.

What we do know(believe) is that SS will try to address any and all problems if and when they occur.

There have been a few occurrences of heat related problems.

There have been a few occurrences of set screw loosening.

What is the percentage of 'occurrences' vs the production volume?

'We' simply do not know.

'They' know. 'They' have responded to those reported to 'them'.


So let us let 'them' ponder over this.

Rjent's apparent component failure is the first that 'we' know of.


BTW the silvery colored 'fins' on the motor have air blowing over them by way of the 'air over motor' fan. The other silvery colored fins have air passing over them on the way to the fan intake(or maybe/also as it passes the motor top). Again we do not know for sure.

JPG wrote:All this 'design' criteria is correct, but the objective of the SS DVR design was to get it all in the 50 year old headstock design(back ward compatibility).

They succeeded it that quite well.

Perhaps the top speed was a poor goal.

Perhaps the heat issues were not properly addressed.

Perhaps because we simply do not know.

What we do know(believe) is that SS will try to address any and all problems if and when they occur.

There have been a few occurrences of heat related problems.

There have been a few occurrences of set screw loosening.

What is the percentage of 'occurrences' vs the production volume?

'We' simply do not know.

'They' know. 'They' have responded to those reported to 'them'.


So let us let 'them' ponder over this.

Rjent's apparent component failure is the first that 'we' know of.


BTW the silvery colored 'fins' on the motor have air blowing over them by way of the 'air over motor' fan. The other silvery colored fins have air passing over them on the way to the fan intake(or maybe/also as it passes the motor top). Again we do not know for sure.

Like you say we don't know! And that is the scary part. This may have been the first failure or it could be one of many others that have occurred to non fourm users.

There is a possibility that every user will experience a failure in the future. So far SS has seemed to make every failure we know of right. Which says a lot for Shopsmith. However we still don't know how pervasive problems might be. I would hope that if there is a basic design problem Shopsmith would engineer a fix and auto ship that fix to all PP owners.

The thing that scares me was the first response by customer service about heat problems. Saying this is normal operation. Huh! Which of us would accept that answer for a car that shuts down after an 8 hour drive?

Best answer would been you need to speak to the design engineer, he will call you.

I'd say if people are worried then de-rate the top speed to say 8000 rpm. Still a lot faster then the stock headstock and if the issue is the heat running at 10,000 rpm then this should help.

The worry has always been how reliable the new powerpro is going to be. We are use to the problems that exist in the earlier designs and have many many years of experience to fall back on. Any parts on the list of most frequently order parts are ones that have issues so it is pretty clear from past experiences the older headstock is not without issues. The good news on the older ones is that the parts are reasonableish and the work is pretty easy to do. The new headstock is an unknown to us.

We are use to machines that are still running after many many years, maybe that is too much to expect from the newer version. Certainly if you bought someone else's tools you would not expect that long a life expectancy. It is that life time partner thing we are use to that might not be as long as we wished.

I didn't get a powerpro for routing, I don't think shopsmiths in any form are as good as a real and true router. Those that have followed my posts know this is not a new thing for me. They, shopsmith don't even attempt to make reducer rings or template inserts and the rip fence my itself is nearly useless unless you add functionality to it yourself.

What I did get it for was the lower speed range, the reverse that is great for lathe work and to lower that amount of maintenance needed. So far so good on those features.

Now I also know that it unlikely that I will be able to continue doing woodworking for ever and I have no idea how many years I have left. Before I laid my money down I thought about this and figured if it would stay running for at least 10 years I'd be happy. If you look at that as $160 a year it seemed reasonable to me. (upgrade prices)

Now if there is a heat issue and it is only at higher rpm then we might see a firmware fix that lowers that 10K number. Or if we see a lot of resentment against shopsmith a class action law action could come to be with in all likely hood would mean they would closer their doors for good.

For now let's wait and see.

Ed

reible wrote:
Now if there is a heat issue and it is only at higher rpm then we might see a firmware fix that lowers that 10K number. Or if we see a lot of resentment against shopsmith a class action law action could come to be with in all likely hood would mean they would closer their doors for good.

For now let's wait and see.

Ed

Wow! Lawsuit! Wait wait wait!
I don't think that should be a consideration.
Anything the involves a lawyer usually comes to no good for anybody but the lawyer. Bottom feeders!

I'm like Ed reible's description of his intended desires for the PowerPro. Slow speed, reverse, which allows me to use SPTs moounted on either or both ends of the machine, and variable speeds. Like ED my machine has been very good for those uses.

Yes, I've has issues when using the bandsaw, but those have been overcome. Yes, I had the controls come loose, and received a new part from Shopsmith.
Yes, I've had a couple set screws come loose. Right now I'm looking for one that came out of a drive coupler. It is somewhere on the floor. No worry! it'll show up.

I would rather use the PowerPro than the mark V.

There is a button on the control panel that will select 9500 RPM. I've used that speed to make a few mortises with no heat issues. Only let the machine work at that speed for as short of time needed. Shut it down between mortises.

As far as litigation - wish it was never mentioned. We all need the company to crry on forever.

Shopsmith doors remaining open should not be an issue. They have been selling PowerPro Upgrades and Mark 7s so fast that they cannot keep parts in stock. The financial crisis appears to be an issue of the past!