Thread: Two speed vice screw

What a neat idea, and since you have the idea of how it works and the dimensions, I will put my order for you to make me one to suit my vice.

Dave

Hi Stuart,

Thanks for posting that, I can't believe how simple it is, I was expecting to see some complex clutch and multicut thread arrangement, just a nut with a fine pitch that stops turning when the jaws start to tighten.

For those who are trying to figure out what this is all about, Stuart was using this vise on the table next to me and Josh on the weekend, and he demonstrated how it had a two speed action. Fast open and close, but automatically slowing down to a different gear ratio when the jaws started to either open or close, so you got the clamping force of a low ratio, with the opening / closing speed of a high ratio.

Simple solution.

Regards
Ray

Hi Dave,
2 tpi square thread? The best I have done is 4tpi with a turning tip lol I'd have to drive the spindle from the leadscrew and RC(?) was talking about on the weekend. Still it is a very nice looking thread.

Originally Posted by RayG

just a nut with a fine pitch that stops turning when the jaws start to tighten.

No problem Ray, though it did take a little to get my head around what was going on. Just to clarify, the nut doesn't have a fine thread, its the difference in pitch between the threads that gives you the "fine thread". Now come put it back together lol

Stuart

Stuart, I think I get the concept but I'm struggling a bit with the detail. Before you put it together can we have a pic of the nut? Obviously the two threads are left and right handed. And one is inside the nut and one outside? So it's a nut within a nut? Is that a spring next to the clip? It sounds so simple and ingenious I really want to get it.

Hi Bryan,
I thought the term "nut" might lead to some confussion.
There are really two nuts.
1. the nut that is bolted to the fixed jaw like most other vices with 2 tpi
2. the knurled brass nut seen in the picture with 2.5 tpi
Both are right hand threads.

The curclip pulls the moving jaw open and the spring ensures that the knurled brass nut moves to the start of its thread as the vice is undone.

I was going to try and explain more but I think I've come up with a way to show it with pictures. back soon.
Ok,
How it would look with the vice open and the work piece loose.


One full turn in, the shaft and the knurled nut have both moved together 1/2"(12.7mm). the jaws now touch the work piece stopping the knurled brass nut from turning with the shaft.



turning the handle roughly 45 degrees(see the line at the red arrow) . The line around the shaft has moved forward from 92.5mm to 88.5mm. The front of the knurled brass nut has only moved from 93mm to 91.5mm



The limit of the thread in the brass nut(line at arrow). The shaft has moved from 92.5mm to 79.5mm. the nut has moved from 93mm to 89mm.



There are some small errors in those numbers, not sure if its measuring/parallax errors or if there is something else going on.

Stuart

bump.
I thought it showed as a new post if a post was edited. It appears that that isnt the case.

By George I think I've got it. Diabolically clever. Thanks a lot for taking the time to photograph and explain it.

I think you only posted that to screw us over.
Thanks for the pictures, I had a good idea but they helped as well.

As for editing, as you found out it wont be a new post. Some people edit there post with out saying they did, so it gets missed by everyone as they don't know and have already read that reply.
Most forums automatically put down the bottom that it was edited, but on here you have to put it in yourself by typing in the reason for edit box.

Dave