Teknatool DVR Motor R&D

[Ed in Tampa]

My thought is there was something wrong in both the last two PowerPros that had overheating problems. Skizzity was having such problems before the recent POP and Quit.

Heat must have been at least a concern for the R&D effort. The following statement was taken from the PowerPro advertisement Where they brag of planing a mile of boards over several weeks time, only an hour at a time.

"We set our Mark V-powered Shopsmith Thickness planer for the fastest feed rate and a 3/64" depth-of-cut... then started feeding our boards through the planer. We continued this process over several weeks in one-hour increments without stopping until we had fed a mile of white oak through our planer... with no bogging, no complaining and no overheating !"

I don't know what headstock speed is needed to get the fastest feed rate on the Pro Planer.

BUT - they never mention running it for long periods at 10,000 RPM.

Of course heat was an issue, they would not have mentioned it had there not been.

[Skizzity]

I would have thought that all of this testing would have been successfully completed BEFORE the PowerPro was fielded. Were there any Beta testers? If there was, were any of them members of the active users community?

Seriously does anyone really believe Shopsmith didn't know about the heat issues?

I'm amazed by some of these comments.

Please show me in the literature where "inverter heat" is mentioned. Please show me in the literature where it says I should only route for a half hour before letting the machine cool down.
As far as can tell, "inverter heat" is from Teknatool. Shopsmith had no clue about "inverter heat" and didn't fully test the motor since nothing is mentioned in the literature.

[Ed in Tampa]

My guess Shopsmith could save the day by bringing out an upgrade of a cooling/muffin fan and filter to solve the issue. If I were them I would automatically include it in the upgrade package and charge existing PP users only what it cost plus handling and shipping.

If just vents would solve the issue I would ship everyone a template of where to put the vent.

I would then include a modified cover with the vents in it to new new customers.

If I owned a Power Pro I would follow Bill Mayo's lead and cut some holes.

Heat is a killer of electronics and if your machine is running hot and even you haven't gotten the over temp error message you are still shorting the life of you electronics.

Major computer users don't spend hundreds of thousands of dollars on air conditioning and chillers to keep the computer electronics cool for no reason.

[Ed in Tampa]

I would have thought that all of this testing would have been successfully completed BEFORE the PowerPro was fielded. Were there any Beta testers? If there was, were any of them members of the active users community?

Seriously does anyone really believe Shopsmith didn't know about the heat issues?

I'm amazed by some of these comments.

Please show me in the literature where "inverter heat" is mentioned. Please show me in the literature where it says I should only route for a half hour before letting the machine cool down.
As far as can tell, "inverter heat" is from Teknatool. Shopsmith had no clue about "inverter heat" and didn't fully test the motor since nothing is mentioned in the literature.

Seriously did you read the Power Pro ad? Why the mention of heat? Why the specific detail that they planned a mile of board feet running only one hour a day over a period of weeks and no overheating.

Did you ever hear of the art of advertising? Use lots of flashy pictures and small print. And never directly mention a limitation only emphasis what is capable of.

[Skizzity]

Seriously does anyone really believe Shopsmith didn't know about the heat issues?

I'm amazed by some of these comments.

Please show me in the literature where "inverter heat" is mentioned. Please show me in the literature where it says I should only route for a half hour before letting the machine cool down.
As far as can tell, "inverter heat" is from Teknatool. Shopsmith had no clue about "inverter heat" and didn't fully test the motor since nothing is mentioned in the literature.

Seriously did you read the Power Pro ad? Why the mention of heat? Why the specific detail that they planned a mile of board feet running only one hour a day over a period of weeks and no overheating.

Did you ever hear of the art of advertising? Use lots of flashy pictures and small print. And never directly mention a limitation only emphasis what is capable of.

http://www.shopsmith.com/ss_forum/maint ... 2-s30.html
Are you referring to the link I posted in that thread? Then yes I read it.

Planing at 4000-5000 rpm is not the same as routing at 9000-10000 rpm.

[dusty]

Everyone is getting testy and this will get us nowhere.

Those with problems should be in regular/frequent/close contact with Shopsmith engineers. Those who do not have the problem (like me) should be sitting back and patiently waiting for words about the resolution.

Shopsmith will resolve this.

The last thing I would do would be to start making modifications. Cooling electronic systems is NOT AS SIMPLE as blowing more air at it. That may delay the final demise but it will not correct the problem(s).

[masonsailor2]

A question Dusty. You stated that cooling electronics is not as simple as blowing air on it. I am asking out of ignorance here. What complications could arise from adding a cooling fan to the headstock ?
Paul

[dusty]

A question Dusty. You stated that cooling electronics is not as simple as blowing air on it. I am asking out of ignorance here. What complications could arise from adding a cooling fan to the headstock ?
Paul

I did not say that adding a fan would create complications. I said that cooling electronics is not as simple as blowing more air on it. If something electrical is generating an unacceptable amount of heat (heat not considered in the design), blowing air across it simply cools it (for now). It does not correct whatever was causing the excessive heat to start with.

Bottom Line: We, here on the forum, do not know enough of the details to speculate intelligently. Is the heat source electrical or mechanical? Is the resulting heat above the temperature tolerance range of the equipment? Likely so, or there would not be an fault condition displayed, Has damage been done? Probably since one of the incidents resulted in a PowerPro that will not now turn on. Are the various incidents that we are aware of in any way related?

Can any of us offer an appropriate corrective action? Absolutely not. Without Shopsmith approval almost anything that might be done could void the warranty or could make the problem even worse.

I, personally, would love to get my hands on one of these failed units. This sort of fault isolation is what a did for years before I retired. However, without technical data, even with hands on very little could be done. Shopsmith is not sharing any of that technical data.

[reible]

There seems to be the idea that adding a bigger badder fan is going to fix things, that is unlikely. Same for venting and all other "common sense" fixes.

I worked in the telephone switching system as a designer at bell labs. We did all manor of design effort to prevent heat problems. The best place to fix these issues are in the design phase and the worst place is after the fact.

When we designed systems we started at the lowest level and attempted to make that the best design we could in all aspects. Heat was of course one of those areas. You did this by looking at component ratings, parts have heat ranges so while you might pay more of a better rated part the reliability also improved if the component was exposed to the higher heat. We also ran computer simulations of air flow and had a pretty good idea how and where hot spots would appear based on that. A trade off of component placement and interconnections of parts had to be evaluated. Use of heat sinks while that seems like a common fix for computer designs is often not the best solution and a heat sink can even make things worse.

OK so now you are wondering why. It all has to do with heat flow and air flow. The components dissipate heat by way of transferring it to the air and transferring it to the area around them. So lets talk about air flow for a moment.

Air moving by needs to be at a certain rate. To slow and not enough heat is going to be released to it and the component will not get cooled. You are looking for some thing called laminar flow verses turbulent flow. Think of air as a stream of liquid if you will. For that picture a stream or river. The river flows in a direction but things disturb the flow. Where water is moving slowly you might not see much disturbance where as if it were running faster you would. As you might not expect sometime a turbulent flow actually helps, but not always.

You also will see eddy currents, those are those little whirlpool currents that you see in a river. As you might expect those little swirls mean the air/water is stagnate to some extent in that it is not moving away but going by again and again. That can become a heat pocket and if it happens at the wrong spot, well you end up adding more heat rather then moving it away.

Air is interesting as well in how it moves. It likes to take a path of least resistance, You might blow it by some things like components on a circuit card but it doesn't mean the air is going to do what you want it to. It might well form a boundary layer and will do nothing to cool the object you want.

I've tried to keep this pretty generic so most of you can grasp the fact that it is a lot more complex then first glance.

Doing things like cutting a hole in the housing might make since but only after it is studied by the engineers involved. In testing we would hook up thermocouples in order to actually read temperatures or use thermoimaging to look at things and know what is happening. Sometimes doing so proved our concepts were right and sometimes we got surprised.

I think the best approach is to let shopsmith know that you have an issue and let them have a look at it. If I were having those problems I certainly would. If and let me stress we don't KNOW if there is a problem in the design or only in a few units and then it could be bad components and have nothing to do with the product line.

Electronics can get very warm and by that I mean HOT and survive fine. We did heat stress on parts to find weak parts so if and only if there were problems in a central office the electronic switches would not have failures and go off line. We even did full scale testing by tenting whole offices and turning off the AC. The quest was to stay operational with a 48 deg. C aisle temperature measured at 5 feet high 18" in front of the frames. When cards failed we would pull them and they were so hot you could hardly handle them. Well over the aisle temperatures.

If you want to think about hot how about under the hood of a car. Back when they started putting computer in cars people were worried. I know of a few people who spent $600 and purchased a spare computer just in case. Well how many of you are even thinking about that now? I worked at a extruded aluminum place and we did the experimental runs of heat sinks for GM. I worked as a draftsman and had to redo engineering drawing of finished parts in to drawings to have the dies made. I can't even tell you how many changes were came before they got a final design. A lot of engineering efforts and testing.

Well I'm getting off subject.

I figure they are a few others here that know about this and if they want to add to it or correct my memories on the subject they would be welcome. Us old retired people sometime forget a lot of what we learned along the way.

Ed

[ERLover]

Very nice explanation Ed!!!