Gidday Fellow Crafters,

I am having difficulties keeping everything centred.

I was turning a cork grip at the weekend and I have managed to create a bulge on one side. I am using a Renzetti and turning the grip on the blank.

Are there any secrets for centering? I am not convinced I am chucking the blank correctly.

Would an additional rollered support help the problem? Also, would the tool rest attachment help? I think my abrasives are hovering over the grip and not cutting concentrically.

Any advice would be greatly appreciated.

Unless you get things round at first, your tools unless you use a tool rest will float over the spots and you will not get things perfectly round. I use my normal lathe tools to get it round at first, then go from there to others for shaping it.

Thanks Mike. What tools are you using to get the cork round from the first instance?

Hi Chris,

All you need to turn cork or EVA foam is abrasive such as sandpaper. If you are turning cork on a blank on a Renzetti and geting a bulge on one side then you have a major problem with the setup or you are doing something very wrong.

How long is the rod blank?
You need to keep the blank as close to level as possible.
Have you already installed the guides?
You do not need a tool rest to turn cork.

Hank
On The Rocks Fishing
Wells, ME.



Edited 1 time(s). Last edit at 04/20/2008 08:35PM by Milton (Hank) Aldridge.

The blank is a nine footer although, I only had one half on the lathe. I regularly turn 7-7'6" blanks.

So it's a 2 piece rod?

With the Renzetti lathe you should have a 3 claw chuck that will connects you blank to the motor. Chuck the blank into the chuck (not so tight is breaks the rod), Space your rod supports evenly along the blank. Be sure the blank is as level as possible and lower the upper clamps on the rod supports to secure the blank. If there is no problem with your lathe the blank should turn true which will allow you to turn the cork true.

Use a sanding block with sandpaper to turn the cork and you should be all set.



Edited 3 time(s). Last edit at 04/20/2008 08:50PM by Milton (Hank) Aldridge.

I think the problem is that the sandpaper is floating around the cork rather than cutting into it. I had the lathe running at full speed and there was no wobble in the blank.

What are you guys using to shape the cork? What is the first abrasive for rough shaping?

all you need is sand paper, keep a steady even presure. Use a 8 long section maybe 1" 1/2 wide hold it in two hands like you are slowly polishing with a rag. and work it back and forth its very easy a little at a time if you try and force it to cut to fast thats when you will get hump somewhere. Keep your RPMS pretty high this will insure you are cutting into the cork evenly all the way around. Also sometime pieces of cork have very hard areas in them (knots? im not sure what to call them). Those areas will not sand down as easy and as quickly as the cork so that could also leave a hump behind. check for that sort of thing by eye and by hand if you find one just sand it down by hand till it catches up with everything else and continue on..

Oh a really heavy grit can also cause this with someone unfamiliar with turning cork.

Good luck.

I usually start with 80 grit paper and work to finer grit from there. I think your problem is that you are not using a sanding block.

Hank
On The Rocks Fishing
Wells, ME.



Edited 1 time(s). Last edit at 04/20/2008 08:54PM by Milton (Hank) Aldridge.

On a lathe....I always use a tool to get the shape and the roundness, once I get close to the size I'm wanting, then I'll swap over to sandpaper. Also I like using a sure foam file (sp?) to cut fast and get unwanted material out of the way in the begining. The only way I can get sandpaper alone to work is to use a sanding block and carefully get things round with some corse grits at the start.

DR

Sandpaper is not enough. Not nearly enough. You must cut the cork concentric to the mandrel or rod blank, and sandpaper will not do that. As was mentioned, sandpaper simply foats over the cork as it is, it will not cut a concentric cylinder.

Use a round nose scraper to cut a concentric cylinder and then sand to shape. That will take care of your problem.

...................

Chris,
Several years ago I had a problem with one of our Renzetti lathes not cutting or boring a hole on center. I pulled out the owners manual and read the section on alignment of the chuck and rail bed. After re- aligning the the chuck with the center of the supports that solved the problem of nonconcertric cork handles.
The process is fairly simple and Renzetti lathes come with plastic shims or you can make the shims out of old double edge razor blades cut in half.

Michael Taylor
Bluewater Fly Tackle

Tom, Is that a 1/2" round nose chisel? There are sets available. Is there much use for the other lathe chisels - skew, vee etc?

Michael, I have checked the lathe and is was perfect right our of the box!!! I wil ceck it again though.

Thanks for all the advice guys.



Edited 1 time(s). Last edit at 04/20/2008 11:22PM by Chris Beverley.

As Tom said tool turn it to get it concentric. You may have some hard spots due to filler being added to the cork. This will not sand as easily as the surrounding surface. Even with a tool rest and a sanding block the paper will still float over the surface to an extent. I have in the past used a surform file ( looks like a cheese grater) to rough the shape in and then when it is round hit it with the sand paper.

Freddwhy (Rapt-Ryte)

Chris,
60-80 grit will cut any cork. But first step is to use a block. I made one by epoxing a strip 4" X 8" 60 grit (or 80) to a piece of perfectly true poplar. You can get it at Home Depot. Weight it while it sets-up so the paper is absolutely flat. I make fly rod grips by gluing 1 1/4" cork rings directly to the blank, not a 1/4" mandrel, so the cork rings are all slightty off-center. I use the black to round everything. Don't force it, just hold the block steady and you will feel the hight spots bumping the block untill all is even. Once that is done I use 80 grit held against a pad I made of closed cell foan which I shaped to a convex surface that I use to form the contours of the fly rod grip. One "MUST" is to always keep the sandpaper moving - sometimes as little as an inch - other times along the whole grip.
Herb L

You cannot lathe sand a cylinder concentric. If it starts out non-concentric, no amount of sanding nor any type of sanding block will create a concentric cylinder. You must cut material in such a way that the cutting tool does not float nor follow the contours of the cylinder .

Using a round nose scraper, size or width isn't very important, set it on the tool rest and hold it a prescribed distance from the cork. I roll a finger under the rest and keep the same amount of scraper protruding past the tool rest as I move the scraper along the length of the cork. You'll notice that the scraper only seems to be cutting from one side of the cylinder. Shut the lathe off and look at what's taking place - cork is being cut from the "high" side and left alone on the low side. At some point, you will begin cutting cork all the way around the circumference. At that point, your cylinder is concentric to the mandrel/blank and you're ready to shape and sand.

.......................

You can also use a coarse wood rasp/file or a stanley surform tool with a tool rest to accomplish getting the cylinder conentric around the mandrel or rod blank. Same drill as with the scraper, you need to ensure the tool is held at the top and bottom, at the same distance from the mandrel as the work spins. This cuts the high side off the cork and trues it up around the mandrel.

I also use the narrow edge of a bastard file as a parting tool to square up the ends as well. This can also be used to cut shoulders and recesses for reelseat inserts, etc.

I've used the scraper on harder cork burls with success and is quicker than the file tools. The files seem to work better on regular cork for me.

Andy's DVD lays this out pretty well, if you want a visual reference.

Terry