Shopsmith Forums

I just purchased an early 1970's shopsmith.
When the seller showed it to me it started up just fine and ran and the speed adjuster worked, but not well due to stripped gears on the the controller knob.

After I got it home I plugged it in and it seems slow to get up to speed and throws the 15 amp breaker after about 5 seconds. I tried a 20 amp breaker and had the same result. So I fired up my air compressor and blew out the sawdust and dirt that was in the headstock and have oiled it. But it still throws the breaker and seems slow to start up. As far as I can tell it is on the slowest speed setting.

I have now installed a new controller knob and discovered the screw shaft on the speed controller is very slightly bent, making it very difficult to adjust. (Probably why the controller knob stripped out.)

Why does my Shopsmith throw the breaker?
Any ideas??
Thanks

Mine will do that if it is set to too high a speed. If it is not at slow, put the sanding disk on and while turning it toward you, rotate the speed control to slow.

CE
There are several why the SS would trip a breaker on start up. The first is usually a voltage problem usually caused by an inadequate supply.
The second is starting while the machine is set to hifg speed. If the V belt is low in the control sheave then youare in HIGH speed which means that the makes more than two RPM for every turn of the motor. This puts extra strain on the motor. This strain is higher if there is a load on the system such as a saw blade or the sanding disc. The most common problem is that the previous owner failed to perform the proper maintenance such as oiling the sheaves properly. Also any tight bearings can also cause this type of problem. The centrifugal swich in the motor can also cause this condition. At high speed the spring on the motor shaft should be extended. At low speed it willl be compressed, do not keep turning the motor on and off while this condition persists as doing so can damage the motor windings.
A thorough cleaning and lubrication will usually fix this type of problem.
Bill V

CE
Please update your profile to let us know where you are. You never know when a member is near enough to you to lend a personal hand.
Bill V

There are more than a few reasons.

The fact that you saw it come up to speed when checking it out would be an indication to me that you don't have any real serious problems.

If you have a volt meter, I would suggest that you measure the primary power (110vac) at the outlet.

If you are using an extension cord - don't.

I assume you have been told to not change the position of the speed dial unless it is running OR you are constantly turning the main drive shaft while changing the speed dial. The easiest way I have found to do this is to mount the sanding disk an use it to turn the shaft (in the normal direction). While turning that sanding disk, you can run the speed dial up to high speed.

At high speed, (no power applied) the sanding disk should be significantly easier to turn than at low speed.

Take off the sanding disk.

At high speed, turn the Mark V on to see if it comes up. What you have done that is different and might change your symptoms is you have changed the position of the belts within the sheaves. Often a unit that has set unused for a long time will be very hard to start and will exhibit the symptoms that you described.

If it starts, let it run for a few minutes (3 or 4) and then SLOWLY run the speed down and back up and down and back up several times. I suggest this as a means of flexing all of the belts and running the belts in and out on the sheaves.

If this does nothing to change your symptoms or the breaker continues to trip - we got more work to do. I guarantee you that you will get all the help you need to resolve this problem.

Come back with a report on your progress.

Do take note of how WA2CRK described high speed and low speed condition. If the speed control shaft is 'bent', the outer speed indicator dial is probably not aligned properly and maybe indicating wrong.

If the speed control knob is not installed properly on the shaft. it will be 'crooked' and make the shaft appear bent. The set screw MUST be aligned with a recess in the shaft. The outer indicator dial must be positioned properly when the knob is installed, or it will not be 'calibrated' properly.

I am concerned as to how you 'tried a 20A breaker'. Replacing breakers in a panel with a larger breaker is 'not recommended'.

If the startup is 'sluggish', tripping after a few seconds is to be expected!!!


I suggest first addressing the apparent bent shaft/knob first.

Then while manually rotating the shafts(temporarily using the sanding disk as a hand wheel makes rotating easier) adjust the speed control knob counter-clockwise as far as it will go. Ignore outer indicator dial for the moment.

It would be a good idea to remove the belt cover so you can observe the floating sheave on the motor shaft while setting the speed control. When at the slow limit, the motor pulley sheaves should be spread and the belt riding close to the bottom.

Remove the sanding disk and try powering it on again.

Let's stop here until you have arrived or have let us know where you ended up!

For the record guys, the direction of manual rotating does not matter.

One of those equal but opposite situations.!;)

[quote="JPG40504"]For the record guys, the direction of manual rotating does not matter.

One of those equal but opposite situations.!]

Thank you oh so much for pointing that out. It would be so terrible to leave the audience with the possible impression that turning backwards was a no no.

Good luck with your problem Cervus_Elaphus. I am going to back away and leave this to the obviously more qualified.

dusty wrote:Good luck with your problem Cervus_Elaphus. I am going to back away and leave this to the obviously more qualified.

Think it through Dusty.

We be creatures of habit and assuming 'forward' only is a normal assumption.

The sheaves will open close/close equally well when rotating either direction.

The control sheave is moved by the porkchop in the direction of the shaft. The control sheave movement towards the belt will cause the leading side of the belt to be pushed up/out regardless of rotation direction.

The floating sheave will auto adjust the belt tension similarly regardless of direction of rotation.

No criticism intended! Only better understanding!:)

And this applies only to the mechanics being discussed.

If not known or otherwise realized, forward only is a good practice!;)