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Chris S.
08-20-2011, 12:54 AM
This is really fast!
http://www.youtube.com/watch?feature=player_detailpage&v=tn7A9PqNftY

Peter.
08-20-2011, 12:56 AM
That's what I use! Got the idea right off this very site a couple of years ago.

darryl
08-20-2011, 01:22 AM
Hmm- seems to me the ball bearing 'trick' was for part alignment. For indicating, he actually used an indicator :)

Nothing wrong with the 'trick' though- I use the basic method all the time, just haven't done it with a bearing before.

But- he misses the boat. Once he tightens the chuck, he's done- but there's still runout, caused by tightening the jaws. He should have brought the torque up a bit after the first alignment with the bearing, then used the bearing again. That's the real beauty of the method- the bearing has both low friction against the workpiece, and by virtue of being solidly mounted it is capable of aligning the part even when the jaws are tighter. A final tightening won't throw the alignment off by as much if you do it in two stages.

macona
08-20-2011, 01:50 AM
Not indicating. Truing.

I think Frank Ford has building one of these on his site.

Paul Alciatore
08-20-2011, 03:09 AM
Oh great, one more shop made tool I just gotta have.

Thanks!

Black_Moons
08-20-2011, 04:16 AM
I liked the cute hack of just welding on two rods insted of making dovetails, though I wonder if it would'nt end up wearing a small dent in the dovetail..

Tony
08-20-2011, 04:21 AM
I just hate to see people leave their key in the chuck like that.
Even if it is 'just for a minute'.

A sense of anxiety just comes out of my screen when i see that.

Neat trick, though.

Peter.
08-20-2011, 04:26 AM
I liked the cute hack of just welding on two rods insted of making dovetails, though I wonder if it would'nt end up wearing a small dent in the dovetail..

Someone on here did it a while ago to hold a large insert holder to his toolpost.

You could almost as easily machine a bevel on one side of some flat bar, cut it to length and weld or bolt the bevels to whatever you want to mount

Forrest Addy
08-20-2011, 05:49 AM
Nice wrinkle. I've seen versions of that many times over the years. Not always bearings, sticks of wood, plastic, ends of tool shanks and so on.

This might be a good time to mention that back in the day apprentices were allowed two whole minutes on a four jaw chuck to dial both ends in to 0.001" - from scratch inserting copper or gasket material padding under the jaws.

Two minutes is a fair amount of time when you come to think about it. When I was a fourth year apprentice old Gruber a senior lathe hand held the watch on me. I finished with a few seconds to spare but plenty before me were quicker and Gruber was quick to let me know my slack and lazy ways would catch up to me. It's a matter of practice. Set yourself a challenge then try to beat it.

The video showed you one way to cheat on the overhung end.

By the way, the guy appears to be an old lathe hand. Notice how short the grip was in his chuck. You don't have to swallow the work to get a good grip on it.

wierdscience
08-20-2011, 09:36 AM
I've got one similar,but mine has two bearings on the radial truing end.The runout he got on the radial truing was due to the internal tolerance of the bearing over running the high center of the part.Two bearings set apart by they're center distance averages the runout down to the round limit of the material.

I also like the rod idea for a q&d toolholder.

skooter
08-20-2011, 09:58 AM
I just hate to see people leave their key in the chuck like that.
Even if it is 'just for a minute'.

A sense of anxiety just comes out of my screen when i see that.

Neat trick, though.

I have to agree there. I once saw a key get from a 10" get thrown 20m across a workshop after someone forgot about it, thankfully nobody was in the way.

However, looking at everything else in that video, one can conclude that he is somewhat.... how shall I put this... Rough.

Andy

Forrest Addy
08-20-2011, 11:17 AM
Speaking of launching chuck keys, one cool advantage of a VFD's controlled accel is it can be set to just give the key a little toss, not throw it hard enough to stick it in your head.

We use to have a line of big Gisholt turret lathes each with 40 HP. No clutch. The go was an across the line motor start. It would accel to 1200 RPM in - I'd swear - 1/10 second. Hit the jog: Bwee!. And the "w" sound was the accel time. They had 20" chucks and if running in reverse a negligent operator could jog the spindle and throw the key about 100 feet into the next bay.

Chris S.
08-20-2011, 11:48 AM
Hmm- seems to me the ball bearing 'trick' was for part alignment. For indicating, he actually used an indicator :)


I guess I should have titled the thread "Super Fast Alignment". ;)

Chris S.
08-20-2011, 11:52 AM
Not indicating. Truing.

I think Frank Ford has building one of these on his site.

Darn!. "Super Fast Truing" then. :D

madwilliamflint
08-20-2011, 12:13 PM
Love it!

Glad I remembered to come on here from home today, when I can actually click on the youtube links, rather than from work.

MichaelP
08-20-2011, 12:29 PM
I think Frank Ford has building one of these on his site.Here it is: http://www.frets.com/HomeShopTech/Tooling/CenteringRoller/centeringroller.html

Chris S.
08-20-2011, 12:58 PM
Here it is: http://www.frets.com/HomeShopTech/Tooling/CenteringRoller/centeringroller.html

Yes, this design is ...uh ... a bit more elegant. ;)

MichaelP
08-20-2011, 02:46 PM
And here is mine:

http://i966.photobucket.com/albums/ae148/MPdisp/Truingtoolforlathework.jpg
http://i966.photobucket.com/albums/ae148/MPdisp/Truingtoolforlathework-closeup.jpg

Forrest Addy
08-20-2011, 02:49 PM
The front face is gravy. It's hanging right out there for anyone to get at with a dial indicator or a roller tool. What if you just turned the piece around to machine the opposite end and you need to dial the face now masked by the jaws so it's parallel to the plane of rotation?

Now if some clever dude would figger a quick way to dial in the BACK side... Parallels and jaw stops are seldom reliable closer than 0.002" because the jaws spring out a little as you tighten the chuck.

I've never found a better way than mounting the DTI on the tool post, dancing it in and out of the jaws by cranking the cross slide to dial in the back side of the work. PITA but when you're done you know where the work references are in relation to the spindle axis. Gotta be a quicker way that's as accurate and reliable.

Robin R
08-20-2011, 05:29 PM
I can see a potential problem with using this technique for cylindrical alignment. If you ran the bearing in even a bit to far, it could walk the part out of the chuck.

lynnl
08-20-2011, 06:54 PM
I've got one similar,but mine has two bearings on the radial truing end.The runout he got on the radial truing was due to the internal tolerance of the bearing over running the high center of the part.Two bearings set apart by they're center distance averages the runout down to the round limit of the material.



Makes sense.
You're describing an arrangement similar to the push type knurling tool, right?

darryl
08-20-2011, 07:00 PM
Yes, the part could walk out of the chuck. You just have to realize that some setups are 'iffy', and pay attention. If you get a feeling that something isn't going to be held sufficiently, you should try to think of ways to help that. One way is to put a rod in a tailstock chuck and use that to prevent a workpiece from moving towards the right- and out of the chuck. You might call that an extended center. It should be pointed and fit a recess in the workpiece, same as a center, although it may or may not be used to actually center the workpiece.

I've used that method in several ways- one of them was to drill a very small diameter hole in the end of the workpiece, and the same in the rod coming from the tailstock. Then insert a short length of music wire or similar- this can work if you need some control, but also need the room for the tooling setup.

This type of thing is also good when parting off washers or the like. Having a rod inserted into the end of the workpiece gives something to catch the pieces as they are parted off. In this case the rod or wire is not used to support the workpiece- it's just a convenience.

I've had an idea in mind for some time now for a steady rest of another kind- one that doesn't mount on the ways or the carriage, but instead mounts on a bar that is bracketed onto the back of the headstock and has another rigid support at the tail end of the bed. Alternatively, it could also be affixed to a bracket mounted on the back of the tailstock. The brackets and the bar are made to be parallel to the spindle axis, and the guide bearing assembly rides the bar for position behind the workpiece. The guides may not be the ultimate in rigidity mounted this way, but it has to be much better than nothing when you're dealing with long pieces, and need the carriage to have unrestricted travel along the bed.

Depending on your level of ingenuity, the bar could double as part of a taper turning aid, and it could also hold a profile pattern that a pivoting tool holder could follow. The bar could also be the attachment point for a dial indicator, or any other secondary motorized accessory such as a grinder.

I'm using the word 'bar', but it would actually be a rigid guideway of some type, so whatever would work for you-

Seems I've digressed a bit- one of the uses I was looking at for the bar was to hold the bearing assembly that would be used in the same manner as shown in the video to align a workpiece. Some means of adjusting the radial position would have to be included in this accessory.