Tool Rest Arm Rotation

twoblocked · Post by **twoblocked** » Fri Mar 18, 2011 7:59 am

swampgator wrote:You gents have just scared the pants off me. Here I was reading up and watching videos on turning with all the safety items to consider. Now, I read this. Will be looking into my systems to see what I can do. Will also be watching to see what solutions you propose and trying to adapt. Thanks for this thread.

What I do is bump the arm toward the work as I make adjustments. Then I know the rest won't move further toward the workpiece. But there have been times where a bad catch will move the rest further away. Not sure which is worse...

algale · Post by **algale** » Fri Mar 18, 2011 2:23 pm

foxtrapper wrote:
Is the rotation actually of 294 on 293? Have you used a marker line to make absolutely sure? For 293 can wiggle in its base as well.

Upon further review by the replay official, I owe an apology to foxtrapper, to whom I originally responded by saying there was no wiggle in the post (293). In fact there was wiggle in the post!

In the 520 (and the 510 and maybe the 505?) there are a series of horizontal grooves cut into the bottom section of the post (293) which mesh with the teeth/gears in the carriage height adjustment mechanism, allowing the tool rest (or main table) to be set via the height adjusted wheel on the carriage.

The grooves that are cut into the wall of the post do not go all the way around the circumfrence of the post but rather go about 1/3 of the way around the post. The post thus will rotate within the carriage until the teeth in the bottoms of these grooves reach the end of the groove and run into the sidewall of the post tube.

Which brings me to the partial solution suggested by twoblocked:

twoblocked wrote: What I do is bump the arm toward the work as I make adjustments. Then I know the rest won't move further toward the workpiece. But there have been times where a bad catch will move the rest further away. Not sure which is worse...

Like twobocked I find that after locking down the carriage height adjustment lock, if I adjust and lock down the arm so that it is slightly further away from the work piece than the final position I want, I can then "bump" the arm (turning the post) until it reaches the limit of its travel. I can then unlock the arm, put it in its final position and lock it down to the top of the post where I want it. Twoblocked is correct that the arm (and tool rest) will still rotate away from the work piece, which presents a problem as well, but one far less terrifying than having it turn towards the workpiece.

Thanks to all for commenting and providing advice and I apologize again to foxtrapper who was right all along.

twoblocked · Post by **twoblocked** » Mon Mar 21, 2011 9:46 am

algale wrote:Upon further review by the replay official, I owe an apology to foxtrapper, to whom I originally responded by saying there was no wiggle in the post (293). In fact there was wiggle in the post!

In the 520 (and the 510 and maybe the 505?) there are a series of horizontal grooves cut into the bottom section of the post (293) which mesh with the teeth/gears in the carriage height adjustment mechanism, allowing the tool rest (or main table) to be set via the height adjusted wheel on the carriage.

The grooves that are cut into the wall of the post do not go all the way around the circumfrence of the post but rather go about 1/3 of the way around the post. The post thus will rotate within the carriage until the teeth in the bottoms of these grooves reach the end of the groove and run into the sidewall of the post tube.

Which brings me to the partial solution suggested by twoblocked:

Like twobocked I find that after locking down the carriage height adjustment lock, if I adjust and lock down the arm so that it is slightly further away from the work piece than the final position I want, I can then "bump" the arm (turning the post) until it reaches the limit of its travel. I can then unlock the arm, put it in its final position and lock it down to the top of the post where I want it. Twoblocked is correct that the arm (and tool rest) will still rotate away from the work piece, which presents a problem as well, but one far less terrifying than having it turn towards the workpiece.

Thanks to all for commenting and providing advice and I apologize again to foxtrapper who was right all along.

Thanks for confirming this!

But then how did the old stylework at all? It has grooves that go around and around like on a screw.

JPG · Post by **JPG** » Mon Mar 21, 2011 11:52 am

twoblocked wrote:Thanks for confirming this!

But then how did the old stylework at all? It has grooves that go around and around like on a screw.

See #10 this thread.

But then I have not done much large bowl turning! Neither do I cut high above the tool rest except for skew shearing.

The 'grooves' are 'concentric rings. The setscrew bottoms out on a wider groove at the top.

twoblocked · Post by **twoblocked** » Mon Mar 21, 2011 12:12 pm

JPG40504 wrote:See #10 this thread.

But then I have not done much large bowl turning! Neither do I cut high above the tool rest except for skew shearing.

The 'grooves' are 'concentric rings. The setscrew bottoms out on a wider groove at the top.

Thanks for the reply!

So there are additional set screws in the carriage? I don't quite understand.

JPG · Post by **JPG** » Mon Mar 21, 2011 1:35 pm

twoblocked wrote:Thanks for the reply!

So there are additional set screws in the carriage? I don't quite understand.

Setscrew retaining the tool rest arm to the vertical post that is inserted into the near elevation hole in the carriage.

twoblocked · Post by **twoblocked** » Mon Mar 21, 2011 2:10 pm

JPG40504 wrote:Setscrew retaining the tool rest arm to the vertical post that is inserted into the near elevation hole in the carriage.

Then is the only thing keeping the post from rotating in the carriage is the elevation lock (pinions)? With my post, I think it is only because the grooves go only part way around the post that it can be locked at all (and not very well). I am wondering what is different that you are able to lock your post to keep it from rotating in the carriage.

JPG · Post by **JPG** » Mon Mar 21, 2011 4:13 pm

twoblocked wrote:Then is the only thing keeping the post from rotating in the carriage is the elevation lock (pinions)? With my post, I think it is only because the grooves go only part way around the post that it can be locked at all (and not very well). I am wondering what is different that you are able to lock your post to keep it from rotating in the carriage.

The table lock also clamps the tubes when tightened. However the shoulder on the pinion gear is round and the post is round, so it is a small contact area. Also with no tube in the back hole, the table lock shaft depends upon the c-clip at the back end of the shaft. Snug will not get er done. Ya gotta get a bit beefy. Maybe the smooth(not 'ribbed') tube does not get gripped as well????

twoblocked · Post by **twoblocked** » Tue Mar 22, 2011 7:28 am

JPG40504 wrote:The table lock also clamps the tubes when tightened. However the shoulder on the pinion gear is round and the post is round, so it is a small contact area. Also with no tube in the back hole, the table lock shaft depends upon the c-clip at the back end of the shaft. Snug will not get er done. Ya gotta get a bit beefy. Maybe the smooth(not 'ribbed') tube does not get gripped as well????

Thanks, makes sense. I took mine apart and cleaned with a scotch brite pad. It seems better, but like you said, I have to really crank down on it to get it to hold well. Maybe I'll pick up an old style post on ebay, or better yet, a universal tool rest!

Thanks again.