Parker Majestic #2 surface grinder

[DavidR8]

That is tough to do with a vertical head. You lift the head to raise it a little then you have to lower into the work. This puts the backlash on the wrong side.

Joe

I was wondering about how gravity affects this situation.

If the lead screw is taking the weight of the motor and spindle and basically controlling the descent then any backlash would be upward.

This would seem to introduce an uncontrolled variable in an otherwise very precise machine.

Conversely if the lead screw is pushing the motor and spindle down then there would be no backlash except when raised.

Or am I thinking about it wrong?

 

[DavidR8]

Finally a valid use for an adjustable wrench!

Sadly my adjustable wrenches were not up to the task and I had to switch to combination wrenches.

 

[7milesup]

I was wondering about how gravity affects this situation.

If the lead screw is taking the weight of the motor and spindle and basically controlling the descent then any backlash would be upward.

This would seem to introduce an uncontrolled variable in an otherwise very precise machine.

Conversely if the lead screw is pushing the motor and spindle down then there would be no backlash except when raised.

Or am I thinking about it wrong?

Just like any of our machines, any backlash is/should be eliminated one you move the handwheel in the desired direction. In my case, my Bridgeport surface grinder has some backlash in the vertical adjustment wheel, but once you are heading "down", that backlash is gone. Each graduation on my vertical wheel is .0001, and I know that this is pretty darn accurate just in observing how it sparks off. I have never put a dial indicator or test indicator on it but I know for a fact that it does not have backlash once you are going in the down direction. I usually move it about .0002 per pass.

 

[7milesup]

Actually missed Sdelivery's post #158. I believe we are saying the same thing.

 

[DavidR8]

Just like any of our machines, any backlash is/should be eliminated one you move the handwheel in the desired direction. In my case, my Bridgeport surface grinder has some backlash in the vertical adjustment wheel, but once you are heading "down", that backlash is gone. Each graduation on my vertical wheel is .0001, and I know that this is pretty darn accurate just in observing how it sparks off. I have never put a dial indicator or test indicator on it but I know for a fact that it does not have backlash once you are going in the down direction. I usually move it about .0002 per pass.

I just tried moving the spindle on mine; no backlash in the down direction unless switching directions, down to up or vice versa.

 

[sdelivery]

That is tough to do with a vertical head. You lift the head to raise it a little then you have to lower into the work. This puts the backlash on the wrong side.

Joe

Not actually and part of the reason we spark out.
If your screw has backlash the wheel could be lifting just slightly and you might notice this if you traverse the part again without moving the head down.
The head/ motor assembly is heavy enough that more than a few tenths lift would be unlikely.
Now let me say this....I have seen both seasoned and unseasoned do some crazy stuff....

 

[7milesup]

I heard from the Walker chuck folks today.
The chuck has somewhat mysterious provenance. The block on the side must be a shop-made addition as is the square actuation drive.
Advice is to clean all the goo out of the inside but to not separate the magnetic pack due to the risk of injury and damage to the components.
I'm to add .25" of 90w gear oil to the base and seal it up with Loctite 77.
I'll have to either make a handle or re-make the square drive because it's a wobble-fest now.
One minor question...how do I measure a hole to size a roll pin?

Somewhat reviving this....
I took my Walker chuck apart today to inspect the handle mechanism. I have never used a magnetic chuck before so no idea how the handle should feel. Mine goes over center with a "clunk". Almost a snap. Just doesn't seem quite right. Is your handle smooth Dave when you operate it?
I noticed that the "over center arm" (not sure if that is what it is called) has a rather sloppy fit on the handle. The other side that is on the magnet fits nicely. I wonder if that is how it is supposed to be.
Also, you say Loctite 77. I can't find any info on that. Are they referencing an anaerobic sealer or what?

 

[sdelivery]

A kinda clunk sounds like a normal manual chuck. Stone one side of your 123 blocks and place it on the clean and stoned chuck turn it on and try to remove the block.
I dont remember loctite 77 being used on a chuck but it is possible. It is a glue like super glue I think.

 

[DavidR8]

Somewhat reviving this....
I took my Walker chuck apart today to inspect the handle mechanism. I have never used a magnetic chuck before so no idea how the handle should feel. Mine goes over center with a "clunk". Almost a snap. Just doesn't seem quite right. Is your handle smooth Dave when you operate it?
I noticed that the "over center arm" (not sure if that is what it is called) has a rather sloppy fit on the handle. The other side that is on the magnet fits nicely. I wonder if that is how it is supposed to be.
Also, you say Loctite 77. I can't find any info on that. Are they referencing an anaerobic sealer or what?

Mine definitely has a distinct ‘over center’ feel when actuated, could definitely be characterized as a snap.

When I had it apart I gained a bit of an understanding of how the mechanism works.
The pins on mine were very snug. The only play in the system is from the poorly fitted square drive part.

The email from Walker Magnetic said to use Loctite 77 Ultra Blue.
Also to put 1/4” of 90 wt gear oil in the bottom of the housing.

 

[7milesup]

Ok. Thanks Dave. I think I am going to have to make a bushing for mine.

EDIT: I looked for Loctite 77 Ultra Blue. Permatex makes a 77 Ultra Blue. It is just blue silicone that is very resistant to oils.
--->Here is the linky<--- to it, although I would not buy it from Fastenal.