Do I Need an Ornamental Lathe for this?
flairwoodworks
| Posted in General Discussion on
I want to start producing tables using the style of legs on the table (attached). When I made these legs, I used a drawknife and spokeshave, but now am looking for a faster method. From what I have seen, ornamental lathes are good for tight twists, but I don’t know if they are capable of cutting such a mild twist (1/8 rotation, two left, two right). Is there another way to do this?
Replies
alternate method
Steam
bendingtwisting? ;-)I can imagine a bandsaw sled that allowed the leg to be rotated on its axis as it was pushed through the saw. You'd still have to guide it through the saw, but the bulk of the waste would be removed pretty quickly.
I thought so too.
I had the same idea of the bandsaw. I just can't figure out the mechanics to ensure a repeatable cut. I don't mind a bit of cleanup.
The problem with the bandsaw is that the blade would get twisted I think.
Here is the way I would go about inventing a repeatable jig. First of all the taper part of the jig should be of the type where the foot of the leg has a small hole in the center of the end so that it can rotate around one point, a dowel or a pin, and free you of the problems of having the angles change as each successive side is tapered. I used this type before I started tapering legs on the jointer.
Next the rotation would be based on two cylinders, one inside the other. The inner tube has a pin sticking out of it that rides in a curved slot cut lengthwise in the outer tube. The tubes have a slightly snug fit. They look exactly like the bolt and bolt carrier in an AR15 rifle. As the bolt is pushed forward in the gun the curved slot rotates it so the locking lugs engage.
If you can picture this rig, center of leg top held by the face of the inner tube, hole in the foot of the leg pivoting on a peg at the foot of the jig, whole thing clamped to a band saw ready to push the far end of the inner tube you are getting close to my idea.
Except for the problem of the blade twisting. Now I have to figure a way to replace the bandsaw with a long straight cut router so the twisting problem of the saw goes away. I'm working on that.
The inner and outer tubes could very easily be made form two pvc pipes that fit inside each other. A flange on the working end of the inner pipe could be glued on and the flange used like the faceplate of a lathe. The curved lengthwise slot in the outer pipe would be rhe length of the full leg twist and the curve of one quarter turn (I think).
EDIT... one eighth turn I guess.
I really doubt any significant twisting would occur unless you tried an absurdly fast feed rate.
The problem is that the rate of feed and the rate of twist have to be done at the same time with the same rate and the same way on each of 4 sides and then again on each of the 4 legs. I'm not too sure if this is reasonable free hand, not for me at least. I also have put kinks in, and broken, band saw blades while freehanding but I usually keep a wide blade on my saw and that could have been me pushling the radius too tight. But, if a thinner band saw blade would accept a twisting cut on two planes then I think my idea using the bolt carrier idea would be perfect. I'm gonna try and make one just to see if it can be done. Don't worry, I'm not thinking of stealing your interesting design. I like my tapered legs trad shaker.
Keep me posted
Good luck with your design. I really hope it works, and I think a 3/8" blade should be able to handle the twist. I'm working on a router carriage jig right now for the twist and it looks promising.
Bingo..
Chris,
Yes, a router carriage jig sounds like the way to go. If you've got a lathe you could mount the blank between centers and build the carriage jig to slip over the bed ways. That would enable you to use the indexing head on the lathe to turn the work to the next surface needing milling.
An alternative would be to screw a square piece of plywood to the end of the blank and just rotate it under your curving, roller-coaster jig. This looks really interesting! Good luck, and please keep us updated with your progress.
Zolton
The repeatable cut is delivered by your own eyes and hands - just as on any freehand cut with a bandsaw or scroll saw. The problem you face is that the work piece will not be well supported by the table throughout the cut. The jig is there to allow the piece to float off the table surface, but still be stable in the plane perpendicular to the blade - i.e., it will resist the downward thrust of the moving the blade. It does not have to be complex or jigged to make the cut for you; it just needs to hold the balnk steady so that you can concentrate on cutting to the line.
gears
We need a gearhead. Literally.
For a bandsaw jig, how about a base that clamps to the table, and a lathe-like leg holder that slides along the base? The leg holder has a rack gear along the edge that turns a pinion gear on the base. The pinion gear, in turn, translates that linear motion into a turn on the leg holder stage at the appropriate turn ratio.That way, the turn/twist is always in the right ratio to the length of linear motion (e.g. the length of the taper).
Sounds complicated
I saw a jig like that online for routing helical flutes. It looks way too complicated for me. My jig is coming along nicely.
GEARS
That is exactly what the jig I am thinking about will do, " translates that linear motion into a turn on the leg holder stage at the appropriate turn ratio." But without gears, using a pin riding in a curved slot exactly like the bolt in a rifle (like an AR15) being pushed forward and turning at the same time in the bolt carrier. It's very simple but almost impossible for me to describe. I'm gonna make one and post pictures.
I'm shocked too since this is a ploy I use on my wife... GET THE LATHE!
Yes!
You absolutely need an ornamental lathe for that!
What's wrong with the rest of you guys? Chris wants to buy an ornamental lathe, and he turned to you for support!
And what did you clowns come up with? Alternative methods!
I'm shocked. Shocked, I tell you!
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