Micrometer Stop (with issue)

[walterwoj]

This is my micrometer Stop based on tubalcain's video on YouTube (if you haven't seen his videos you are missing out!)

It fits well, has a graduated dial and the bluing came out perfect!

The dial is off a little bit though, I have learned the hard way that there should be 49 divisions on it, not 50 so it has an extra hash mark (lol), but it looks right. I used red nail polish to highlight the marks.

It just has one problem:. It moves! When I tighten the knob down as hard as I can by hand it seems really tight; I can't move it by hand, but as soon as the carriage touches it, it moves. If I run the carriage by hand it moves with the slightest touch and when the carriage is under power (not threading though!) It pushes it right allong the ways.

Did I build it wrong or does it just take a lot more clamping force to resist the carriage?

Here are a couple pics of the pieces:

Sent from my Pixel 6 Pro using Tapatalk

 

[woodchucker]

This is my micrometer Stop based on tubalcain's video on YouTube (if you haven't seen his videos you are missing out!)

It fits well, has a graduated dial and the bluing came out perfect!

The dial is off a little bit though, I have learned the hard way that there should be 49 divisions on it, not 50 so it has an extra hash mark (lol), but it looks right. I used red nail polish to highlight the marks.

It just has one problem:. It moves! When I tighten the knob down as hard as I can by hand it seems really tight; I can't move it by hand, but as soon as the carriage touches it, it moves. If I run the carriage by hand it moves with the slightest touch and when the carriage is under power (not threading though!) It pushes it right allong the ways.

Did I build it wrong or does it just take a lot more clamping force to resist the carriage?

Here are a couple pics of the pieces:

Sent from my Pixel 6 Pro using Tapatalk

Wow, your chuck is very close to the ways. How big is your lathe, and what size chuck is that?
Be careful when opening your jaws or bringing the carriage in close.

 

[Ken226]

Just a possibility, but based on this screen capture, zoomed in from your pic,

It looks like maybe your lower clamping block is being pulled against the carriage stop and not so much against the underside of the ways.

If so, perhaps mill a about 30 thousandths off the bottom of the carriage stop.



Also, letting the powerfeed push a carried stop down the ways would scare me! I'd be scared of breaking something, but then, I'm a chicken!

 

[walterwoj]

Wow, your chuck is very close to the ways. How big is your lathe, and what size chuck is that?
Be careful when opening your jaws or bringing the carriage in close.

It's a 10 1/4-1/2 in lathe and that is a 10 inch chuck! It's tight and I am always careful of the jaws for that reason. The carriage has enough room to run under the chuck without issue but it's tight, don't want my finger in there when it's running. someday I want to get a 5-6 inch 4 jaw for it. I have a 6 in 3 jaw but due to some mistakes I made, the jaws are messed up and I need to acquire a post grinder to fix so it doesn't see much use right now.

 

[RJSakowski]

Modify your clamp as below to create a pivot point. Make tha pivot as far back as possible for best leverage.

 

[woodchucker]

It's a 10 1/4-1/2 in lathe and that is a 10 inch chuck! It's tight and I am always careful of the jaws for that reason. The carriage has enough room to run under the chuck without issue but it's tight, don't want my finger in there when it's running. someday I want to get a 5-6 inch 4 jaw for it. I have a 6 in 3 jaw but due to some mistakes I made, the jaws are messed up and I need to acquire a post grinder to fix so it doesn't see much use right now.

just so you know if you don't, that chuck is meant for a 14 - 16 inch lathe. Be careful.. yea your finger, or metal flying..
Like they used to say on Hill Street Blues... lets be careful out there.
Good luck.. stay safe.

 

[walterwoj]

Just a possibility, but based on this screen capture, zoomed in from your pic,

It looks like maybe your lower clamping block is being pulled against the carriage stop and not so much against the underside of the ways.

If so, perhaps mill a about 30 thousandths off the bottom of the carriage stop.



Also, letting the powerfeed push a carried stop down the ways would scare me! I'd be scared of breaking something, but then, I'm a chicken!

I thought that was a possibility so already I did just what you suggested, I am sure it is not bottoming out but it did not fix or even improve the situation.

I have to admit I don't know the use of the carriage stop very well but I ASS-U-MEd that it should be able to stop the carriage under power-feed. I have tested it well away from the chuck where I can stop it before it does damage. I know that using it when threading is a no-no but I'm sure it should work when I am hand feeding it, but it just slides. I'm beginning to think the reason that every version I've seen before has a bold is hat you need a wrench to get enough torque to hold it tight.... It WILL hold if I take a pair of pliers to the thumbscrew, but I was trying to make it tool-less, I might just cut a hex head into the top of the thumb screw....

 

[walterwoj]

Modify your clamp as below to create a pivot point. Make tha pivot as far back as possible for best leverage.View attachment 388756

RJ what mechanical advantage does that give? Wouldn't it only grip on the tip on the right? (also I would have to cut down the body of the stop to gain enough clearance for that so I might save that for last resort as there is currently a broken tap in the stop and I don't have a endmill that would survive that operation.... As tubalcain would say, I have painted myself into a corner....)

 

[Ken226]

I have to admit I don't know the use of the carriage stop very well but I ASS-U-MEd that it should be able to stop the carriage under power-feed.

Unless there's some mechanism or clutch that I don't know about to kick the powerfeed off when the carriage contacts the micrometer stop, something will likely break/bend.

My lathe definitely wouldn't auto-off the powerfeed when it hits the carriage stop. I only use the stop while hand-feeding.

For the block,

Try the design that RJSakowski posted. The added leverage will help. It doesn't give mechanical advantage, it just causes the block to transfer all it's force to the underside of the ways instead of into the body of the carriage stop.

If you use the same block to do it, you will also need to take an equal amount off the bottom of the carriage stop, so the block is level when in contact with the underside of the ways. Otherwise the screw itself will take the stress of it trying to pivot, and not allow enough force be applied to the ways.

 

[RJSakowski]

RJ what mechanical advantage does that give? Wouldn't it only grip on the tip on the right? (also I would have to cut down the body of the stop to gain enough clearance for that so I might save that for last resort as there is currently a broken tap in the stop and I don't have a endmill that would survive that operation.... As tubalcain would say, I have painted myself into a corner....)

The gripping force on the lathe way will always be less than the clamping force of the screw, the ratio of which is inversely proportional to the respective distances to the fulcrum. (3rd class lever). The decrease can be minimized by making the two distances as near as possible to equal, hence the longer distance to the pivot point. You should be able to increase your clamping force by around 3X.