Help on turning split columns

[Swifty]

Hi,

I'm asking for a little guidance. I need to put half columns on a small door, 30mm diameter or so with decorated ends, all up around 500mm long. So I will need to laminate two pieces, gluing a piece of paper lengthways between.

(I searched the forum but couldn't find anything...:()

Any particular glue should I use, does it matter what sort of paper I use, any other points - should i slow down the lathe, for instance??

Thanks!

[SawDustSniffer]

um, the first and last time i tryed , pva and A4 printer paper worked well , leave 5mm of length on the side you end up butchering with ya chisel when seperating , dock it off on a drop saw ,as for speed the slowest workable speed , and dont do ya tail stop up to tight as to split it up before you start

[oldiephred]

Not sure I fully understand your application but: I have found it useful to make the blank a couple of cm. longer then put screws through at each end to help hold things together and reduce the splitting forces from the center and drive dog. This also gives a good place to split with the chesil.
I have , at times used screws in the turned areas and then used plugs to fill the holes IF the job is to be painted.
Sometimes the glue jobs can be a real SOB to get apart, contrary to what the "experts" show.

rotsa ruck

[Toolin Around]

Hi,

I'm asking for a little guidance. I need to put half columns on a small door, 30mm diameter or so with decorated ends, all up around 500mm long. So I will need to laminate two pieces, gluing a piece of paper lengthways between.

(I searched the forum but couldn't find anything...:()

Any particular glue should I use, does it matter what sort of paper I use, any other points - should i slow down the lathe, for instance??

Thanks!


Regular white glue will work fine - don't cheap out on the amount you use.

News paper is the best - there's less coatings on it and only use one or 2 layers between the pieces. I've found one to be the best but YMMV.

Don't drive the spur center into the glue line - should be obvious but seen people do it. A tail stock centre with only a large point (not a cup centre) can be a bit risky if not careful - I wouldn't use one at all.

Cause of the sudden and dramatic way these turnings can let go a face shield would be a good idea.

Cause it's such a small diameter centrifugal force due to high rmps won't be much of a factor. But whip from the length combined with the small diameter will.

Sounds like you haven't done this before so it's probably a good idea to: I do this when I'm unsure of the pieces ability to stay together when working it. Leave 40 or 50mm on each end. When you have it mounted on the lathe wrap a few layers around both ends with duct tape or black electricians tape. Make sure you wrap it in the right direction or the tape may un-ravel. This will eliminate the any chance of the piece completely separating on the lathe (which can be a bit un-nerving to say the least when they do let go).

Pay attention to the sound being made. If you get a rhythmic and rapid tick stop and check that the piece isn't starting to separate.

When done use a chisel to begin the break apart. If done properly there will be a fair bit of resistance to splitting at the very beginning (from the end of course) - just be patient. Once they start to split it becomes easy to separate.

If the timber starts to split instead of the paper layer don't continue on at that end as it will only get worse (unless you can get a thin knife in there and cut the fibers of the timber free to stop it) - a good reason to leave the extra ends on till you've split the parts.

Other than that the rest is up to you.

[Barry_White]

Swifty

As a Patternmaker we used to do this all the time because we had to be able to mount the two halves of the pattern on each side of the molding board to create the mold for the casting.

The way we used to do it is exactly as oldiephred says. No glue or paper just the two halves screwed together at each end.

[China]

Go with what Barry And oldiephred said, by the time you muck around with glue and paper you will have them turned up and on the doors

[Skew ChiDAMN!!]

For turning a split column, yeah a screw in the waste at each end is the way to go, unless you're turning long, very thin items, such as lace bobbins. Then hot melt glue is the way to go... otherwise splitting it apart again when finished is a major drama.

I use good PVA and brown paper (as in lunch bags) for split pieces I can't screw together... eg. there's not enough waste on the end or I'm turning a hollow form. Split goblets make for a great conversation piece, provided you've turned 'em properly and have a nice, thin bowl. :)

[oldiephred]

It's not good to be old so please help. I don't understand Skew's comment about split goblets. Does this mean half goblets. two kinds of wood,??. They sound interesting so Could you tell us more.

Regards:

[Skew ChiDAMN!!]

Yes... half goblets that're turned in basically the same way as split columns. I tend to mount 'em on book-ends and the like, but some people like 'em as standalone items. I'd like to make one with a captive ring holding the two halves loosely together but I haven't yet worked out a way to manage that. (Yet.)

I started making 'em when I was looking for a quick way to turn scoops. (Which were a dismal failure, BTW. The handle becomes too weak for the scoops to be used.)

[Swifty]

Thank you Forum Members for informative responses. There appears to be a "glue" school and a "non-glue screw" school of thought out there. I will give thought to both of these and then proceed to the job in hand. You were quite correct - I haven't done this before and am only recently initiated into the turning fraternity (or sorority if you are of the other gender). I will let you know if anything disastrous happens!