Mark 5 doesn’t start

[Dloz]

I am new so please be patient.

I have an old mark 5. At least 30 years old. It was last used for turning about 4 years ago.
It now wont run, it tries to run about 2 dozen rotations and then the circuit breaker trips.
I have rotated it counter clockwise while turning the speed control to slow.
When doing so the speed control goes from easy to tight or tight it easy.

Thoughts on this?

[dusty]

Before you attempt to run it ANY MORE clean the inside of the headstock and lubricate.

[DLB]

In addition to lubrication, as Dusty said, sometimes the belts take on a 'set' which makes them harder to turn. Automotive belt dressing helps to return flexibility.

It is best to ensure the Mark 5/V is the only thing on the electrical circuit, especially while troubleshooting. Using no extension cords is best, especially while troubleshooting. If extensions must be used, minimize length and maximize wire diameter. I use only 12 AWG, though sometimes 14 AWG will work for short runs. 16 AWG or worse is likely to cause the problem you are having. (This varies with shop wiring, distance from breaker panel, etc.)

You can ensure that the headstock is actually set to low speed by inspection through the hole under the name plate on the rear of the headstock. (Unless it is way older than 30 years.) For SLOW, the lower belt should be riding near the outer perimeter of the Idler sheaves/pulley and be deep into the motor sheaves/pulley. SLOW is the ideal start speed for the headstock, easiest for the motor.

When the motor trying to start draws enough current to trip the breaker its internal wiring is also getting hot. Give it plenty of time to cool between attempts.

Personally, I like to remove the lower belt and make sure that the motor starts and runs normally without the load of the headstock. This is because the problem can be either internal or external to the motor. The motor should start and reach normal speed very quickly when unloaded, I would estimate less than one second.

- David

[Dloz]

Thanks for all your suggestions. None work, it is a very old model i am assuming. The shopsmith logo when removed does not provide access it just exposes a single screw hole. I removed the cover exposing the belt and there are no visible oil holes on the motor shaft (under the spring). All online videos show a model with access by the logo medal when it is removed.
Further thoughts or ideas are greatly appreciated

[Dloz]

It is a model mark5 made in 1954

[JPG]

IF it IS as you described, it is indeed more than 30 yrs old(Think 1950ish). Also it is likely green and silver colored.

Does the quill shaft rotate by hand(It will have belt resistance depending upon where the speed control is set)

If it rotates so slowly that you can count the revolutions, it is NOT starting correctly. If it merely hums and 'tries' to rotate it MAY be the start switch internal to the motor.

I agree with DLB to attempt with the belt removed from the motor pulley. Removing the belt will also allow checking the mechanical stuff fer binds etc..

[Dloz]

I removed the belt and motor runs fine, i am able to rotate the quill by hand (with resistance)
I was able to lubricate th peed shaft and the motor shaft.
Tested with no change.

[JPG]

With the motor belt removed, the quill shaft should rotate fairly easily.

I suggest first removing the quill and checking it first.

There are two other assemblies(idler and main shaft bearings) that may be contributing to the problem, but they are much more involved in getting hands on to them.

[chapmanruss]

Since you have followed David's suggestions along with Dusty's lubrication recommendation and none worked, I would suspect there may be bearings that need to be replaced. If the motor is running fine without the belt attached extra strain is coming from somewhere. This will require some headstock disassembly. The first and easiest bearing to check is in the Quill. It can be removed after the set screw on the top of the Headstock near the Quill end is backed out. This set screw is covered with putty at the factory. Extend the Quill until it disengages from the Pinion Gear and remove. CAUTION do not release the handle of the Pinion Assembly but turn it back until the spring is relaxed to avoid damage. Turn the Spindle in the Quill to see if the Bearing needs replacing. It should turn smoothly and freely.

If the Quill is in good condition the next parts to check are the Idler and Drive Sleeve Bearings. This will require more disassembly of the Headstock parts. This will be easier if the motor pan is removed from the Headstock Casting. Remove the switch with the motor. The Speed Control Assembly needs to be released from the back of the Idler Shaft Assembly. That is the wire loop. The Idler Shaft Assembly can be removed from the Headstock Casting and off the upper belt. Check the Bearing for smooth and free turning. Do the same for the Drive Sleeve Assembly which does not need to be removed to check it. If any of these bearing are hard to turn or rough when turned, they should be replaced. During reassembly while it is still out lubricate the Idler Shaft with a few drops of lightweight oil over the key and move the sheave back and forth to spread it. If there is no oil hole in the Idler Sheave for lubrication this is the best way to get it properly lubricated after having no use for a long time.

If there is no hole in the motor shaft's moving sheave, then carefully "pry" the sheaves apart and oil the shaft.

[chapmanruss]

The picture below shows the set screw location indicated by the arrow which needs to be backed out to be able to remove the Quill.

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Quill Set Screw.jpg (215.65 KiB) Viewed 294 times

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The picture below shows the loop from the back of the Idler Shaft Assembly indicated by the arrow that needs to be removed from the "porkchop" of the Speed Control Assembly. This view from the bottom has the Motor Pan removed.

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pre restoration Headstock

Headstock inside view.jpg (155.69 KiB) Viewed 294 times

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The above casting is a "B" Headstock with the access hole (at the back end of the arrow) which allows lubricating the Idler Shaft Sheave and the gears of the Speed Control Assembly.

To remove the Idler Shaft Assembly, it is helpful to first remove the Speed Control Assembly. This is done by removing the handle first and the three screws the hold the assembly in place. Be careful not to lose spring behind the dial in later headstocks like the "B" Headstock shown in the picture below. "A" Headstocks did not have that spring behind the Speed Control Assembly.

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Speed Control Spring.jpg (87.24 KiB) Viewed 294 times

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The picture below shows the end of the Idler Shaft Assembly held in the Headstock Casting. This is a later "B" Greenie Headstock and earlier "A" Headstocks will not have, unless modified, the screw at the top of the mounting hole. Remove the Cap Screw and nut at the bottom of the opening to allow the Idler Shaft Assembly to push back into the Headstock to remove. Some "A" Headstocks have a Bearing Retainer (P/N A3274) that the Cap Screw goes through to help keep the Bearing/Eccentric in place. This was an addition not in the original production of the Mark 5. It can be found in the second edition of the Owner's Guide 7:54 on page 26.

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Idler Shaft 1956 Greenie.jpg (79.39 KiB) Viewed 294 times