Lathe / Face Plate Run out ...narrow vessel hallowing

[richardrouse]

Been awhile since I've had a chance to post on here.

I'm goofing around with the lathe, and running into two problems.

The first, when doing face plate turnings... as soon as I remove the tailstock my workpiece turns out of round. Is this a runout issue with the quill? or is this an issue with the way I've attached the workpiece to the face plate?

I haven't actually put a dial on the quill yet to see if I have a run out issue there. I do drill straight and true holes with the same shopsmith.

It is an older greenie with a single bering quill though...So I'm not sure if the extra mass of the work piece is causing a problem to present itself.


My second question is in regard to hallowing out a narrow vessel like the one I have pictured. This is a sleeve for a travel mug insert. This is how I hallowed it out..

I bored the material out in steps.. starting with a 3/4 forstener and working my way up to a 2 1/8" forstner. Then I used a round nosed scraper to widen the bore to just under 3 inches at the mouth and then it tapers to 2 1/8 at the bottom. When i went to the scraper I put the tool rest perpendicular to the workpiece, slightly above the center line and moved the scraper into the left side of the workpiece (relative to me looking down the way tubes from the tailstock end of the shopsmith.

I really had to fight to keep control of the chisel and constantly caught my chisel in the work piece.. The inside of the vessel looks like an angry beaver hollowed it out.

Any advice is appreciated.

[masonsailor2]

It has to be one of three things for the piece to be out of round. First how the piece is attached to the faceplate. Make sure the screws are tight. Second would be the faceplate itself is warped but that is probably the least likely. Last would be the quill. If it's a single bearing quill it very well may be the culprit. You can put a dial indicator on it to see but if it's that old I would just replace it. It's a 5 min procedure and I think they are about $100. You will be amazed at the improvement of the machine. As far as the hollowing out of the piece get the tool rest down inside the piece to give your chisel as much support as you can. A hollowing chisel which has a curve to the piece is the tool of choice and if you want to spend the big bucks one of the chisels with the round carbide insert is the best. They are amazing but the job can be done with a standard round nose scraper with very good results. The trick there is to grind the chisel to bring the bevel further back along the side of the chisel to give a sharp edge further down the side of the tool. This will allow you to use the lateral edge of the tool to cut with. Just go slow and it will work fine.
Paul

[masonsailor2]

Another factor is that it is a tall narrow piece and it may just need support. You can build a support out of plywood and two skateboard wheels that attaches to the way tubes which will cure that issue.
Paul

[JPG]

Two bearing quill 'conversion' will cost more that $100 if your Greenie is still a Gilmer drive since it would also include replacing the drive sleeve/pulley and bearings, idler sheave and possibly the control sheave and idler shaft and bearing(s).

[reible]

For the moment I guess anything could be the issue. Did you line up the head stock and tail stock point to point and have that about as perfect as you could? Sometimes that can be an issue due to the setscrews in the tail stock having been taking a beating over the years and not wanting to stay where you want them. You can also add a second set screw to the tail stock, I have a post here somewhere with directions on how to do that.

You didn't say how you attached this to a face plate so I will add a comment about doing that. This was how I did such things before I got a Nova G3 chuck that I now use for a lot of things rather then a face plate. You will need a scrap piece of wood that gets attached to the face plate with screws. You will want it slightly larger then the face plate a some what round.

After mounting the piece to the face plate you will turn it round and flat. Locate the center and using a small nail drive it in at the center. Clip the nail head off so that say a 1/4" is exposed.

Take your work piece and find the center of both ends. Make a small indent at the center then with a piece of paper cut to the same size as the face plate you will glue the pieces together with the paper between. The nail will find the center mark and then clamp in the lathe using the quill to apply pressure.

Once the glue is dry, preferably overnight and then maybe a bit more you will be ready to turn the outside between centers. It is OK to turn the waste block a little if need be to work on that end of the piece.

BTW the AL face plate I had from shopsmith was not flat. I turned mine to get it flat but the intermediary wood piece fixes that for you.

Now it could be you have other issues like the quill and if you can afford the newer two bearing quill it is a nice addition to the machine. If not putting in a new bearing is not that hard to do and might help if the old one is worn.

So those are a few things to think about.

Ed

[wa2crk]

Richard
Reible gave you some good advice. You would be VERY surprised how much downward force is applied to a lathe tool when cutting.
When you reach out further from the tool rest the worse it gets because you have less mechanical advantage at the handle.
A right angle tool rest reaching into the vessel would probably help a bunch.
If the turning was stable with the tailstock engaged then it was probably the tailstock that was doing the holding. When the tailstock is removed and the piece is either out of round or turning off center then I would suspect something in the mounting or the quill.
Make sure that the faceplate fits the spindle properly and that is inserted all the way onto the quill to avoid loosening. Also make sure that the proper set screw is being used. Flat point not cupped.
If you run into problems I am just up the road.
Bill V

[Mike907]

Hollowing a vessel that deep with a scraper is going to require very light cuts with a very sharp scraper. The edge of the scraper should be about centerline, so you may have had the tool rest too high. As has been pointed out, there will be a lot of torque applied to the scraper by the wood since the scraper is hanging so far off the tool rest, so the longer the scraper handle, the better. A lot of stabilizing systems have been invented to combat this problem. If you don't have one, go very slow, and hold on tight.

https://www.youtube.com/watch?v=RxWJAdWLn_Y

Mike

[richardrouse]

Another factor is that it is a tall narrow piece and it may just need support. You can build a support out of plywood and two skateboard wheels that attaches to the way tubes which will cure that issue.
Paul

That sounds interesting. I'm guessing that the support is somewhat similar to the supports that I've seen on here for polishing bench and way tubes. I think I will have to give that a try.

[richardrouse]

Two bearing quill 'conversion' will cost more that $100 if your Greenie is still a Gilmer drive since it would also include replacing the drive sleeve/pulley and bearings, idler sheave and possibly the control sheave and idler shaft and bearing(s).

Yup its a gilmer belt drive. So I'd be replacing everything on the upper portion of the head including the bearings.. Only because it'd be apart already and bearings are cheap to replace.. So why not.

[JPG]

Two bearing quill 'conversion' will cost more that $100 if your Greenie is still a Gilmer drive since it would also include replacing the drive sleeve/pulley and bearings, idler sheave and possibly the control sheave and idler shaft and bearing(s).

Yup its a gilmer belt drive. So I'd be replacing everything on the upper portion of the head including the bearings.. Only because it'd be apart already and bearings are cheap to replace.. So why not.

Bearings yes. But they come with the drive sleeve.

The rest. . . . . Idler sheave also.