Shopsmith Forums

So this afternoon my friend and I decided to use a volt test to see why the Shopsmith would not come on, other than the damaged cord. Turns out the cord is getting power, and the motor is getting power, but nothing happens when the power switch is flipped. We took the headstock off and opened things up.

Here is the motor.


We now get everything completely opened, and look at this mess.



I turn the shop vac on it. Definitely need to detail clean and lubricate the headstock before doing anything. Opening the headstock up was as far as we got as it was close to cigar time, and you don't dare interrupt cigar time.

rdavidp wrote:So this afternoon my friend and I decided to use a volt test to see why the Shopsmith would not come on, other than the damaged cord. Turns out the cord is getting power, and the motor is getting power, but nothing happens when the power switch is flipped. We took the headstock off and opened things up.....you don't dare interrupt cigar time.

Did you suspect the power switch is not working? Enjoy that cigar!:)

charlese wrote:Did you suspect the power switch is not working? Enjoy that cigar!:)

Kind of hard to really tell with all of the sawdust. I could even see dust caked on the copper coil in the motor. Everything is coated. We opened the headstock and it was like cutting open a full vacuum cleaner dust bag. Before replacing the power switch, I am going to clean and lubricate the parts, and then replace the power cord because even though it gets power, it is damaged, frayed, and is made mostly of electrical tape. I will probably have to take the head stock all the way down to get everying properly cleaned, and in doing so will inspect everything and make sure it works.

The cigars were good.

rdavidp wrote:Kind of hard to really tell with all of the sawdust. I could even see dust caked on the copper coil in the motor. Everything is coated. We opened the headstock and it was like cutting open a full vacuum cleaner dust bag. Before replacing the power switch, I am going to clean and lubricate the parts, and then replace the power cord because even though it gets power, it is damaged, frayed, and is made mostly of electrical tape. I will probably have to take the head stock all the way down to get everying properly cleaned, and in doing so will inspect everything and make sure it works.

The cigars were good.

That thinking is good also!

JPG40504 wrote:That thinking is good also!

I am tempted to see if the ShopSmith will start working just from cleaning out all the saw dust.

rdavidp wrote:I am tempted to see if the ShopSmith will start working just from cleaning out all the saw dust.

OK as a temporary, intermediate effort!;)


However, since you already have the motor 'separated', checking it prior to 'reuniting' would be appropriate!:rolleyes:

Secure the motor before connecting 'power'.

rdavidp wrote:I am tempted to see if the ShopSmith will start working just from cleaning out all the saw dust.

There is a very, very good chance that some sawdust has gotten into the contacts of the centrifugal switch. This would prevent start up. Therefore, there is a very good chance that a thorough cleaning out of the motor will resolve the problem. In the meantime:

An ohm meter check, across the ac hot and ac neutral contacts of the power cord to the Mark 5, will give you an indication if the switch is good. Just connect the ohm meter as described and flip the on/off switch back and forth. If there is continuity through the switch, power cord and start windings, you will see the switching action on the meter.

NO POWER APPLIED FOR THIS TEST

I would suggest that you vacuum out all the saw dust you can and then use compressed air to further remove saw dust from the innards.

Good Luck. Hope you are making new sawdust very soon.

The resistance of the run winding is less than one ohm.

The resistance of the start winding is about 5 ohms.

When the start(centrifugal) switch is 'made', the run and start windings are connected in parallel to each other.

Detecting the 5 ohm start winding in parallel with the fractional ohm run winding would be difficult at best from the power cord.

A accurate low ohm reading meter would be required.


This would be a good power switch check.

JPG40504 wrote:The resistance of the run winding is less than one ohm.

The resistance of the start winding is about 5 ohms.

When the start(centrifugal) switch is 'made', the run and start windings are connected in parallel to each other.

Detecting the 5 ohm start winding in parallel with the fractional ohm run winding would be difficult at best from the power cord.

A accurate low ohm reading meter would be required.


This would be a good power switch check.

To check continuity as I was intending with this comment, all one needs is to see some low resistance with the switch "ON" versus an extreme high reading (like infinity) when the switch is "OFF".

If this occurs, there is continuity through the centrifugal switch and the motor should at least hum, if not run, when power is applied.

ADDITIONAL COMMENT: When the motor is not running (no power applied as when ON/OFF switch is OFF), the centrifugal switch is relaxed and there is continuity through that switch and the start windings. When the motor is turned on and comes up to speed, the centrifugal switch opens and in so doing removes the start winding from the circuit. The quick test that I was proposing simply verifies that with power removed there is a path for current flow from the power cord through the motor start windings and centrifugal switch and back to the power cord. Seeing the meter move or hearing the continuity tester simply confirms that path and the fact that it can be completed or broken by the on/off switch.

It is NOT a quantitative test of components in the circuit. It is a quick test that gives an indication of whether there is connection through the centrifugal switch and/or on/off switch. If there is NO meter action at all, plan on replacing the switch or working on the motor.

BTW This test can be done with a cheap continuity test light.

dusty wrote:To check continuity as I was intending with this comment, all one needs is to see some low resistance with the switch "ON" versus an extreme high reading (like infinity) when the switch is "OFF".

If this occurs, there is continuity through the centrifugal switch and the motor should at least hum, if not run, when power is applied.

ADDITIONAL COMMENT: When the motor is not running (no power applied as when ON/OFF switch is OFF), the centrifugal switch is relaxed and there is continuity through that switch and the start windings. When the motor is turned on and comes up to speed, the centrifugal switch opens and in so doing removes the start winding from the circuit. The quick test that I was proposing simply verifies that with power removed there is a path for current flow from the power cord through the motor start windings and centrifugal switch and back to the power cord. Seeing the meter move or hearing the continuity tester simply confirms that path and the fact that it can be completed or broken by the on/off switch.

It is NOT a quantitative test of components in the circuit. It is a quick test that gives an indication of whether there is connection through the centrifugal switch and/or on/off switch. If there is NO meter action at all, plan on replacing the switch or working on the motor.

BTW This test can be done with a cheap continuity test light.

Gotta persist Dusty!

There is no way to determine if the start switch contacts are made from the power cord, Unless the normal resistance of the run windings is known, the normal start winding resistance is known and a meter capable of detecting the lowered resistance resulting by the parallel connection of the two windings. Using 5 and .5 ohms, the parallel combination is .45 ohms.