Shopsmith Forums

So I was thinking about my boat. I know, it's January in Minnesota but what the heck. My boat has a monster 24 volt trolling motor powered by 2 deep cycle 12 volt batteries. They run all day and charge at night. Variable speed. See where I'm going here? I think a 24 volt dc motor could power my 10E lathe nicely, with variable speed. Even when the power is out

Here's a nice 1 hp motor: http://www.amazon.com/gp/product/B009YJ ... PDKIKX0DER

Bill Mayo, JPG and other gurus please do let me know what you think.

Tom

Nice motor.

What is the available power at lower rpm?

The recommended controller is inadequate.

Speed-torque curves are available here -- it's the "economy" E30-150 model. Unfortunately, they don't show the continuous torque/power curves, and the efficiency curve is confusing to me. JPG, can you decipher it?

At 1 hp peak, I'd guess that the motor is somewhere around 1/3 hp continuous. It will depend to some extent on the heat sinking.

Another concern is the bearings. I once designed a motion-control system that used a $2000 brushless servomotor. Like this motor, it had a 1/2" shaft and ball bearings on the output-shaft end. The max side load on those ball bearings was 40 lb, so you have to be careful if using a belt drive. That configuration was really intended to drive a ball screw, with no side loading on the motor shaft. Motors designed for belt drives typically have roller bearings on the output shaft.

A major motor manufacturer once sold my company a 10hp custom servomotor for a belt-drive spindle application. I gave them all the torque and side-load specs, but they screwed up and sold us motors that weren't designed for a belt drive. Well, after a few months of operation, the motor shaft on one of the first production units fatigued and broke clean in two -- inside the motor! (Our customer reported a really bad grinding sound when they turned it on -- only nothing moved. ) The manufacturer redesigned the motor to use roller bearings on the output, and made the shaft 6 times stronger. They replaced all of the original motors under warranty, but replacing them was our field-service headache.

Thanks guys. I didn't think of the bearings. This very small motor may not be the best candidate.

tomsalwasser wrote:Thanks guys. I didn't think of the bearings. This very small motor may not be the best candidate.

An understatement I think.

Sorry BD I think this one does not deserve deeper examination!

I enjoyed the bike video so for me it was worth the experience of visiting the site.

I often wonder if they still have WWII vintage dc motors that were in planes and were used to open bomb bay doors. Many many years ago my brother built his own powered wheel chair and used one of these. If memory serves me they were 56 volt motors??? Seem like an odd voltage but they worked on 4 car batteries. The design required a good deal of torque at start up but these were up to the task.

I remember having large 48V power supplies at work that we used for some of phone company work, we ended up dumping them at the end of the project except for a couple we squirrel away for rainy days. I bet they are still sitting in some lab today. Wish I had one to play with for some DC projects. They had two rows of large capacitors, one along each side, we harvested some of those for other projects, they were about the size of a quart of paint but a little longer.

Ed

tomsalwasser wrote:So I was thinking about my boat. I know, it's January in Minnesota but what the heck. My boat has a monster 24 volt trolling motor powered by 2 deep cycle 12 volt batteries. They run all day and charge at night. Variable speed. See where I'm going here? I think a 24 volt dc motor could power my 10E lathe nicely, with variable speed. Even when the power is out

Here's a nice 1 hp motor: http://www.amazon.com/gp/product/B009YJ ... PDKIKX0DER

Bill Mayo, JPG and other gurus please do let me know what you think.

Tom

I believe you would be very disappointed with this motor. I found that the 90 VDC motors really lacks sufficient power at the slower speeds when I used one in a Mark V headstock. I found I had to go to the 180 VDC motor to get sufficient power in the lower RPM range (50-200 rpm). Of course, I found almost no one had 220 VAC to power the controller in their shop so I was not able to sell the headstock with the 180 VDC motor. I sold the motor and controller to a metal lathe owner.

billmayo wrote:I believe you would be very disappointed with this motor.

Thanks Bill. You are the master when it comes to thinking outside the box and then actually making something no one else could. I know you've adapted a Mark V headstock to a power station (pictured below). How about adapting a power station speed changer to a 10E lathe? The 10E/ER speed changers are very rare and power stations are ubiquitous.

reible wrote:I enjoyed the bike video so for me it was worth the experience of visiting the site. Ed

Ed, I was wondering what bike video you were referring to until I dug deeper into the site Dennis linked. That motor has a lot of guts!

[youtube]https://www.youtube.com/watch?v=O5FlG4ADOuY[/youtube]

Here's the "outboard" setup I use for sanding, finishing and other slow speed work. Reversible, too. It's a small 12v motor, so it's not up to the task of full-time duty.