Instead of Repairs, Can Mark V Run Lowest Speed Only?

[JPG]

Latest on Sheave replacement and circuit brkr tripping repair.

My repair parts are in plus I ER disassembled the spring-loaded parts from the end of the motor shafts sheave.

The neck of the sheave had sheared off of the sheave and had slipped to the extreme end of that shaft and had likely jammed the whole mechanism, thus causing an immediate short circuit.

I'm not much of a mechanic-- more of a woodworker, so I have some mechanic's question to you mechanical gurus.

1. The diameter of the hole in the neck of sheave is IDENTICAL to the motor's shaft, not even a 1/64th to spare. It comes in at exactly 5/8" diam. 1/64=0.156 which is terribly sloppy - 0.626 on a 0.625 shaft is a nice tight fit = 0.627 might be better it it needs to slide(with lubrication) YES 1/64 IS A TIGHT WOOD FIT MECHANICALLY, NOT SO MUCH

1A. So am I supposed to add penetrating oil lubricant to the hole and shaft and tap it on w rubber mallet? NO! #10 MACHINE OIL MAYBE, BUT IT SHOULD EASILY SLIP ON (if properly aligned first)

1B. Or should I use emory cloth on the shaft removing 1/128" or so?NO NO NO !!!!!!

1C. Other tips?

I do know that the sheave neck's key slot needs to align w key mounted in shaft.

2. When done with that task, I'll be swapping out the speed changing mechanism that broke, but that looks like a simple operation other than:

2A. How to zero-up the speed dial with the worm gear? Perform a high speed adjustment - that is the next to last step.
2B. Should sheaves be in expanded or closed positions on the shaft when zeroing up to slow speed? The idler pulley and motor pulley sheaves will ALWAYS be the opposite of each other - one open, other closed - FAST = idler open, motor closed.
2C. I know motor is to always be started up in slo-mo, so how do I attain that w sheave positioning on both shafts plus V-belt install? see below

Tx in advance for the addtl help.

The motor belt is installed with the speed control and sheaves set to FAST(that opens the idler pulley so as to have max belt slack when slipping the belt onto the motor pulley with it manually opened.

BTW the dial is set to FAST, and SLOW is whatever results from all the tolerances intertwining.

[DLB]

1C. Other tips?

2C. I know motor is to always be started up in slo-mo, so how do I attain that w sheave positioning on both shafts plus V-belt install?

A couple of other tips and recommendations. Your motor shaft may be dirty (almost always are) or corroded (much less likely). Even with religious maintenance, I find that the shaft gets gunk in there that just occasionally needs to be removed. It is easier to clean and polish the motor shaft with the key removed and the motor running doing most of the work. To remove the key you must remove the other sheave (fan sheave). There is a single set screw locking it to the key. Conveniently, it uses a 5/32 allen wrench. Behind the fan sheave there is a spacer that sets the fan sheave spacing from the motor bearing. If that comes off easily, take it off so you don't lose it. If it does not come off easily just leave it on. You want to end up with the floating sheave easy to slide in and out on the shaft.

Control sheave works pretty much the same way, and needs to slide easily on the idler shaft. This is easy to check while the speed control is out of the way.

To adjust the speed to slow without the motor running, you can do this by manually rotating the headstock shafts while adjusting the speed. This is easiest with a sanding disc installed. Since you are turning it slowly, adjust the speed slowly. Personally, I don't always start mine on slow. I won't start it on fast, but any speed up to Saw/Joint has always worked for me.

JPG meant 1/64" = 0.0156" but still terribly sloppy.

If your belt is the right width (1/2" at the wide part minimum) then Fast will be with the belt about 1/8" from the outer edge of the motor sheaves. Slow will be with the belt about 1/8" from the outer edge of the Idler sheaves. Belt width should be checked before doing the high speed adjustment.

- David

[ALarryAaron]

Tx for ur continual help.
Waited overnight. Sheave still won't mount to shaft.

Won't even slide on to its out most part. Can't get sheaves collar the least bit started onto the shaft.

Alignment isn't the problem, cuz collar of sheave not even mounting on shaft a d is far from the intersection with shaft's key

Any tricks?

[DLB]

It's possible the key came up outside of its slot in the motor shaft, but you are saying you are not getting far enough for the key to interfere, correct?

Is this a new sheave bought from Shopsmith? Or ??? Did the old sheave pieces come off easily?

Can you post good pics of the motor shaft and inside bore of the new sheave?

Did you have any issues removing the clip, washer/cup, and spring?

You might go ahead and remove the fan sheave as discussed as a test to see if it slides reasonably well over the shaft. Should be the same bore.

- David

[ALarryAaron]

Hi David. TX for reply.

Yes part came from shopsmith.
Slid broken sheave off of shaft w no effort.

Made clamping jig per Jacob Anderson video to hold down spring/washer/retaining ring while disassembling but retaining ring was hard coming off and was damaged but will but new one.

Key is not issue at this point cuz collar not onto shaft. It's too tight to get started.

I hadn't removed fan sheave yet, I don't see how that will help me get the sliding sheave on. BTW: the collar that broke off of the floating sheave will still slide onto shaft.

Both the old broken sheave collar and the new one measure IDENTICALLY, 15.87mm (5/8") using digital Micrometer. The old one goes on and off of the shaft although sticky going on at first. The new one won't even get started onto end of shaft.

I micd the shaft and the tip is 3-4 hundredths of mm wider at tip of shaft that the rest of the shaft, so that may explain why even the old one is a bit sticky to get on. Perhaps shafts are machined a teeny bit bigger at tip than rest of shank?

Am trying to attach photos of motor's shaft and new sliding sheave but pics don't show up in preview mode of post, so assume they r not getting enclosed w message.(perhaps cuz I'm posting from cell phone rather than PC?)

So will submit anyways.

Wd heating or freezing motor/shaft or sheave help? I think new sheave will slide freely once it's onto the shaft just like the broken sheave's collar does.

[ALarryAaron]

As said earlier, I'm a woodworker, not a machinist.

Perhaps I'm not using micrometer properly. Can't get consistent readings 3 times in a row at same point on shaft--at least not within. 03mm. Frustrating!

Are you supposed to start wider and the slide calipers onto the shaft or force calipers open w sliding action?

Measuring ID, use very tips of caliper or first 1/4.of face

[ALarryAaron]

Correction. Am using caliper - - not micrometer as stated earlier

[JPG]

Since the retaining ring was damaged getting it off, the shaft likely was also damaged in the process.

Using fine emery cloth BUFF the end around the retaining ring groove. I predict it will at first feel rough. Be non agressive, sneak up on it.

BTW it MUST be aligned perfectly to slide on. A speck of oil on the shaft might help get it started. Very soft touch required or it might wedge and get jammed.

Iphone pix are likely TOO large(error message not obvious).

[DLB]

I hadn't removed fan sheave yet, I don't see how that will help me get the sliding sheave on.
Agree. It will only tell us how the fan sheave fits relative to the shaft and end of shaft.
I micd the shaft and the tip is 3-4 hundredths of mm wider at tip of shaft that the rest of the shaft, so that may explain why even the old one is a bit sticky to get on. Perhaps shafts are machined a teeny bit bigger at tip than rest of shank?
I don't think so. 0.04mm is about .0016" (1.6 thou) American. Inspect closely for something deposited there that shouldn't be there, or anything out of round, burrs, etc. I guess it could be slightly mushroomed from someone using a puller on the end of the shaft, but that seems unlikely. How far up the shaft until you get a normal measurement? If it was me and I was sure of the measurements I would take this down to the right diameter, but no further. You don't want to screw up the groove that the snap ring fits in.
Wd heating or freezing motor/shaft or sheave help? I think new sheave will slide freely once it's onto the shaft just like the broken sheave's collar does.
It might work, I wouldn't do it. You currently have an interference fit that is not intended. The shaft is very hard and the sheave is not, you don't want to risk damage.

I have one I can take off and measure the shaft. It will be later today.

- David

[JPG]

Now let us speak of precise measuring using calipers.

You say the shaft measures 15.87 mm.

5/8" is 15.875 mm. That .005 mm is almost 2 thousandths(0.001968)

Measuring at this scale requires some practice to do so accurately. Technique(incorrect type) can destroy any hope of repeatability.

Hope I got the decimal points correct this time!

HEED DLB's advice just posted!!!