Grind Mate - what goes in the "lock" hole....

...and what does it lock?

I had never noticed this before, only saw it in the photo when editing for a post on making a rotary broach on the woodworking forum. Don't think the Master Grind includes this? looking in the hole, there appear to be 2, (or maybe 3) layers, the center, (or maybe bottom of the top layer) seems to have a fine thread. But I don't want to go trying screws until understanding what it's for.

Is it perhaps a method to lock the spindle between detents, instead of using the stops on the rim of the faceplate?




This is an older Suburban Grind Mate/GM-3-V

Thanks!
smt

Yes, sometimes the 15° intervals aren't enough and the hard stops are most often used for swinging a radius tangent to flats, putting a crown on a perforator, etc. If it's a used coffee grinder of dubious vintage then the locking capability is directly proportionate to the number of ham fisted people that have used it divided by how expensive the workpiece is. I would attempt to verify this, for safety, before trusting it. If in doubt use the hard stops for backup. The spindle lock is also used to set rotation to the hard stops if so desired. The Harig I have uses a 10-32 x 1-1/8 SHCS, the Acro appears to use the same but can't vouch for whether they're OEM or not. If it were my choice I'd purchase/insert a brass tip on the SHCS just because I don't know what it presses against and the case hardened tip of a SHCS may be harder than what I'm mashing when applying the lock. If you decide not to do the brass tip no one will ever know if photos aren't posted. I thought the Master Grind had a lock too but my memory can be unreliable.

Hee, hee...

If it's a used coffee grinder of dubious vintage then the locking capability is directly proportionate to the number of ham fisted people that have used it divided by how expensive the workpiece is

Click to expand...

AFAIK it was a one owner model from a (really) NASA shop in TX. It was acquired by a woodworker/luthier about 10 years ago in a larger lot,who generously made it available to me. But your description is apropos - the faint threads i can see look either partially stripped or slightly buggered. They look about 1/4-28 (or at least 1/4" "fine" thread. That diameter would give a little more space for a brass tip, thanks for mentioning that.

The tool came in original case with some loose thumbscrews (none of which fit the lock hole). I've used it sporadically since. I've made a fair number of punches and routinely spin pins and small tool shanks, but often just use a cheap spindex to avoid getting the GM dirty I think i never moved the friction handle before, and it covered the hole. So didn't notice the "lock" inscription until it popped out on the photo. For this job, I had already set up the blank and decided to move the handle to rough prompt me where 90° was relating to the tool.

Which brings up another question - on some, like the Neubold (which I've never used) apparently loosening the screws on the back of the plate allows the degree wheel to be rotated in relation to the spindle. (IOW, set up the tool, find the reference feature on the tool, adjust or -0- the degree wheel to reference the feature for direct reading). Does the GM have an intentional means to turn the degree scale independent of the spindle? Certainly not needed, but would hate to continue overlooking potentially useful features if they exist.

I've used the stops as you suggest, to limit a swing. A rough look with a scale to center suggests using the feature for sine setting, the pin distance is 2.5" ? (Yeah, I know, set it up and indicate measure)

A final Q - there is a small SS (#10 or maybe 1/4" size) straight down in the center of the top of the casting. Does that have a purpose beyond maybe being an oil fill plug?

Thanks!

smt

Pretty sure mine has a cap screw in the lock hole, used to lock it. I'll check tonight for size and length.

Took a look and it's a cap screw, but the head is larger than the hole in the scale, so I can't remove it. My scale seems to be held with both rivets and double stick adhesive or tape.

Conrad - thanks for making the effort for me.

Is yours a GM-3-V or a later model?

Guess I'll gingerly try some likely screws, and then maybe call the factory.
Or maybe in another decade or 2 I still won't need that feature and they can bury it with me

smt

There is a disc about 3/4 diameter and 3/32 thick inside the end cap. They tend to lock up depending on direction of rotation so some people remove the screw.Not used often but nice to have.

That's useful info if I ever pursue things further - thanks for the tip.

smt