Shopsmith Forums

BuckeyeDennis wrote: . . .
I have a Technatool DVR motor speed/torque curve that shows it can still produce about 0.9 hp continuously at 5000 RPM. So my educated guess is that Shopsmith chose to rate the motor for a higher speed, and settle for a lower continuous-power capability at top speed. This is entirely consistent with the reports of over-temperature alarms when routing at top speed for an extended period of time.

What is the HP available at 2300 rpm?

I assume the speed/torque chart is at a specified pulse voltage etc.?

JPG wrote:

BuckeyeDennis wrote: . . .
I have a Technatool DVR motor speed/torque curve that shows it can still produce about 0.9 hp continuously at 5000 RPM. So my educated guess is that Shopsmith chose to rate the motor for a higher speed, and settle for a lower continuous-power capability at top speed. This is entirely consistent with the reports of over-temperature alarms when routing at top speed for an extended period of time.

What is the HP available at 2300 rpm?

I assume the speed/torque chart is at a specified pulse voltage etc.?

Here's a copy of the original torque curve that I snipped from a Technatool motor brochure some time back -- it specifies 115V operation.
I used Visio to measure the points on Technatool's torque curve. Note that the X-axis interval on the torque curve is not constant, and something (I forget exactly what) made me think that the the torque points had been shifted 1/2 increment to the right on the plot. So I adjusted the corresponding RPM values accordingly, and wrote a simple Excel spreadsheet to generate the power curve.

I assume that the torque curve is for continuous torque, in which case the curve I generated is a continuous-power curve. This is consistent with all the reports of improved sawing power, vs the 1-1/8 hp (continuous) standard induction motor. In which case, for low duty-factor applications such as hobby woodworking, the usable instantaneous power from the DVR motor is almost certainly considerably higher than my power curve would indicate.

HMMMM! So SS's 1 3/4 occurs at about 700 rpm and falls closer to 1 hp at 250.

I would have liked to see it increase sooner)(closer to 2300[6400/10000 x 3600]).

A temp rise vs rpm would be interesting!

Does the PowerPro allow the operator to select an operating speed that is inappropriate for the task being performed?

Example: Set the operating speed at 10000 when set up to saw or drill.

I think I understand that the PowerPro adjusts the operating speed based on load variations.

Example: Cutting hardwood rather than softwood and that this adjustment is made without operator intervention.

dusty wrote:Does the PowerPro allow the operator to select an operating speed that is inappropriate for the task being performed?

Example: Set the operating speed at 10000 when set up to saw or drill.

I think I understand that the PowerPro adjusts the operating speed based on load variations.

Example: Cutting hardwood rather than softwood and that this adjustment is made without operator intervention.

The powerpro has a chart function which allows you to go through functions and pick what is closes to what you are intending to do. So say you wanted to do some drilling, then you pick drill and then you can pick the size of bit, ie 1/4" or less.... /hard wood/twist drill and the other things like sawing have similar selections. The powerpro has no idea what you really have attached so it is up to you to what you tell it what you have.

Once you have selected the function and specification you "confirm". Say it had recommended a speed of 1800 rpm for that drilling operation, the 1800 is displayed and when you push the start button nothing happens because it is above the threshold of 1500 rpm so you have to confirm again to have it turn on.

So say you had your bandsaw attached and the speed was set to 10000 rpm. If you push the on button it ask you to confirm and if you do the powerpro starts your band saw at 10000.......

There is no safe guard for you being dumb. It does have that one extra step the the conventional headstock does not. Speed dial set at max and you flip the switch and away it goes, so a potential disaster is one step closer.

I do like the chart function, it gets you into the ball park on operations but sometimes I just set the speed by what I think I need or want. For example drill some pine at 1800 or 1400 doesn't really make a whole lot of difference. If I'm getting a decent hole and good chip removal I'm good to go. Like wise pushing the button for a decent saw speed is faster and easier then using the chart so that is the way I go.

Hope this helps.

Ed

Thank you, Ed. That is not what I had hoped to hear but it helps. I am once again in a heated debate with myself as I try to decide if I should become a PowerPro owner/user. My woodworking challenges are not as many as they once were as age sets in and because I can do most everything that I want/need with my Mark V. That as much as anything makes the decision very difficult for me.

Yes as for me it is a matter of 'want', not real 'need'. But then I have some extra SSs and SPTs that I 'wanted'. They came gradually and at far less $$$$ each.

Since I have already purchased two powerpro's I no longer have your problems on that account.

I had for a time thought about getting another one(number 3) but now I'm collection Festool stuff so I don't see that I will be making any major shopsmith purchases again. In fact I will more then likely part with a machine or two since I really don't have the space to support as many as I have. I will keep the powerpro ones as I have become quite attached to them.

If you think the powerpro is expensive then you are not in to Festool stuff. The tools I hope to get from them this year could get me a new mark7..... but even then I could really do without any new tools for the rest of my life and still have a very functional shop.

I have not finished my tool budget, I'm running late on that since it starts Dec. 1. I do have a number of smaller purchases I've made but those have been minimal. No plans for any major purchases until Feb.

But back to the powerpro, I'm well pleased with mine and no buyers remorse is happening here. They do what I need doing and do it well. I have not seen the heat issues but then other then a few times when I was playing with the powerpro for some routing projects I don't run at full speed. I think one needs to use dust collection and if you do then some of the other problems are less likely to present themselves. Yes some people have seen problems but then there are also many who have not.

Ed

reible wrote:Since I have already purchased two powerpro's I no longer have your problems on that account.

I had for a time thought about getting another one(number 3) but now I'm collection Festool stuff so I don't see that I will be making any major shopsmith purchases again. In fact I will more then likely part with a machine or two since I really don't have the space to support as many as I have. I will keep the powerpro ones as I have become quite attached to them.

If you think the powerpro is expensive then you are not in to Festool stuff. The tools I hope to get from them this year could get me a new mark7..... but even then I could really do without any new tools for the rest of my life and still have a very functional shop.

I have not finished my tool budget, I'm running late on that since it starts Dec. 1. I do have a number of smaller purchases I've made but those have been minimal. No plans for any major purchases until Feb.

But back to the powerpro, I'm well pleased with mine and no buyers remorse is happening here. They do what I need doing and do it well. I have not seen the heat issues but then other then a few times when I was playing with the powerpro for some routing projects I don't run at full speed. I think one needs to use dust collection and if you do then some of the other problems are less likely to present themselves. Yes some people have seen problems but then there are also many who have not.

Ed

but then there are also many who have not

That is a big part of the problem. There is no valid metric for this. Just what percentage of the units sold have been reported as inoperative. We see/read many negative reports but the real number of negative reports could be a very, very small percentage of the fully functional units that are in service. Shopsmith does not help with this because they are secretive about production numbers. The old serial numbering system sorta helped in this area. Users knew how many machines had been produced.

wa2crk wrote:Dusty
The only consideration is the ratio of the spindle speed to the motor speed. The ratio of the idler pulley to the drive sleeve pulley is 2.0 divided by 1.25 equals 1.6. So 10,000 RPM spindle speed would be 16,000 RPM auxiliary shaft speed. The ratio of the auxiliary sleeve pulley to the motor pulley is 1.25 divided by 3.125 equals 0.4. therefore the motor RPM is calculated by multiplying the 16,000 auxiliary shaft speed by the 0.4 ratio equals 6400RPM.
The ratio of the motor pulley to the drive shaft pulley is 2.0 divided by 3.125 equals 0.64. so 10,000 spindle speed times the 0.64 ratio equals a motor RPM of 6400 RPM

I don't know why the DVR motor would be limited to 5500 RPM. Theoretically it should be able to run as fast as the microprocessor can switch as long as the motor's armature is properly balanced.
Bill V

I have information now that will result in "slightly" different6 numbers. I managed to get my grubby hands on a powerpro motor pulley.This one measures 3.1735" (3 11/64"). The puzzle still remains though. How does the PowerPro reach 10,000 rpm spindle speed if the motor tops out at 5500rpm? Bottom line I suspect is it doesn't. Therefore, the motor is running at a speed greater than the "advertised" top speed of 5500rpm which does not alarm me at all.

Furthermore, all of this supposition will be just that if we find out that the idler pulley is different than assumed. I forget to check when I could have put my hands on one.