Mark V headstock knocking sound

[bshaff]

I replaced the bearings in my Mark V about 2 years ago and have not used it much since because of moving etc. Now I am using it again it has a knocking sound coming from the head stock when it runs. It sounds like marbles in it.

Any suggestions as to how to trouble shoot this. Thanks Barry

[everettdavis]

Mount the sanding disk on the quill so you can rotate the system by hand.

Rotate it and listen and feel how it is to the touch as you rotate it by hand. Never move the speed dial unless you are manually rotating the quill by hand, or have the motor on. It will bend things in the speed mechanism.

Remove the inspection cover on the back side of the headstock and look at the quadrant that moves the floating sheave as part of the speed change mechanism. Is it bent or out of place in any way. There is a bearing in the end of the idler pulley with a button that rubs on the face of the quadrant. That bearing can be failing and make noises like you describe.

As you rotate the sanding disk, you are moving all the belts and pulleys. That may give you some initial indication either visually or audibly.

Next, If you haven’t found anything specific, take off the belt cover and go ahead and do the full oiling / lubricating procedure to insure the idler sheave (upper) and floating sheave (lower) on the motor are free, grease the button at the quadrant where it rubs, and inspect the drive belt and Poly-V (Gilmer if older unit). They can have belt set or be wearing.

If you still haven’t found anything certain, follow the procedure to remove the drive belt from the motor and see if you can spin the motor by hand to isolate if it is motor bearings.

Look at the auxiliary spindle and eccentric to make sure it hasn't walked out of the headstock and rubbing.

You can also remove the quill and see if it is quill bearings etc. if you think it is coming from the drive shaft assembly area.

By now you should have seen most of the mechanisms and have a good notion on where the noise is coming from. There are numerous posts to help you fix anything you find wrong in the inspection.

Anytime a Mark V sits for months, it should be cleaned and lubricated before powering it up.

[wa2crk]

I am with Everett. The small bearing in the end of the control sheave may be the problem. When it goes bad the sheave can wobble on the shaft and possibly cause a knocking sound.
Bill V

[JPG]

I vote for belt set.

Second, control sheave wobble caused by keyway or key wear(made apparent by poly-v belt set).

Try belt conditioner.

[bshaff]

Thanks guys. I checked these things and all seems ok. I can move my idler bearings that are in the ecentric bushing a tad up and down. Maybe that is the problem. I broke the headstock where it screws into the front. One of the three screw holes broke off when I was putting the speed dial back on. Is there any way to fix that or do I have to buy a whole new headstock?

Thanks

[JPG]

Thanks guys. I checked these things and all seems ok. I can move my idler bearings that are in the ecentric bushing a tad up and down. Maybe that is the problem. I broke the headstock where it screws into the front. One of the three screw holes broke off when I was putting the speed dial back on. Is there any way to fix that or do I have to buy a whole new headstock?

Thanks

Yah, I can see that causing 'knocking' sheaves.

A little ingenuity can fix the broken ear. Which one broke?

[billmayo]

I have use JB Weld with a flat washer and nut on the inside of the broken ear. You need to be careful when doing this. I remove the speed control assembly and put he screw, washer ands nut in the speed control assembly where the ear is broken. I use a little JB Weld on the inside of the washer to hold it when tighten. I was able to rock the speed control assembly around so I could insert it with the screw, washer and nut. Then I use my finger inside the headstock to hold the nut from turning and tighten the screw.

[bshaff]

The one on the left side broke. Also do you think I need to purchase a new idler bearing for this or can I use this one until it gets real bad and then change it?

[everettdavis]

The one on the left side broke. Also do you think I need to purchase a new idler bearing for this or can I use this one until it gets real bad and then change it?

If you can move it by hand, it's already real bad. Fix it.

When you look into this you will likely find if you are doing this through Shopsmith, there is a whole new style of shaft, requiring a new type of eccentric.

You should be able to find one on eBay that is serviceable in your present style.

As others have stated read the top two sticky posts in Maintenance for valuable information.

I also contributed an article with a PDF you might find helpful titled Buying a Used Shopsmith Revisited that takes you through a bunch of the machine and helps identify specifically what you have and what you see with used equipment.

http://www.shopsmith.com/ss_forum/maint ... 16113.html

It has lots of photos and links to posts in the forum, even shows you the old and new style idlers and eccentrics etc.

I would not use it at all until repairs are made. Repairs are something you can do, and those two sticky posts have links to everything you might need, and more.

[bshaff]

I think my problem was that when I replaced the idler bearings 2 years ago I did not replace the ecentric bushing and I think that causes it to be loose. I put the old idler bearing in and it fits fine and stopped my knocking. I ordered a new ecentric bushing for the new idler bearings and in the future will put them together and hopefully it will work. Until then I will use the old one. Question: How hot is the machine suppose to run? The upper part where the quill is only on the other side of the headstock is real hot to the touch after about 1 hr of lathe work.
Thanks,