View Full Version : Twisted Square Column

11-12-2011, 05:42 PM
I was thinking about the conversion problem from real world 3D to rotary jig. I wondered what type of surface would carve to be a square. I plotted a twisted square column in a math program called Maple and converted it to what I believe will produce it on the rotary jig. I am hoping someone with the rotary jig will give it a go.

01-15-2012, 05:53 PM
I just carved the twisted square column. This is the first test of my prototype rotary jig. The dowel was 2 inch diameter and 6 inches long. The jig will hold pretty well any diameter or length dowel which fits in the machine. The jig was in the machine from start to finish. The machine measured the dowel (also, the bit touched down on the dowel for the depth measurement). Even though the prototype is crude, I am pretty happy with the outcome. Look how well the end of the carve lined up.

01-15-2012, 05:58 PM
Now that came out really good. Ya gonna show off your jig at all, looks interesting from what little we can see and I like the idea of variable sizes too.

01-15-2012, 06:02 PM
Definitely Impressive!! -- Nice Job on your Prototype

01-15-2012, 06:23 PM
I just happened on your post. I do the same thing using a spindlel sander. I'd be interested in seeing your prototype when you get it finished.
Dominic Bruno
Land O Lakes FL.

01-15-2012, 06:57 PM
Ok, here is a picture. You cannot see all of the parts. I am hesitant to post the jig details. I do not want to get anybody upset. I am not trying to compete with Ed's rotary jig or damage his sales. I am really interested in the math involved and the problem of making a versatile jig for myself. I have much yet to do. I was going through the measurement routine and it made it through! I could not help but to try and carve something.

01-15-2012, 07:14 PM
Thats cool I see you raised the power drive a little with adjustable y... perfect indexing 2.
I do expect to see a lot more rotor jigs down the road, that's the nature of the design application I think.

01-16-2012, 07:34 AM
Very cool.

01-16-2012, 11:37 AM
Bergerud, Good Job on the Rotary. I like it. Before there was a car there was a horse drawn carrage, then came a steam car, and now you can get a car that runs 200 MPH or more.. I'm glad that I was a part of the steam car portion of Carvewright Rotary carving.

Ed Baker

01-16-2012, 12:04 PM
Wow.. What did I post that violated the rules? Several have been deleted along with replies to them.. They were just ideas about how to push the envelope of the CW..???

01-16-2012, 01:25 PM
Steve, I think your post is still there. If it's the one in the thread titled "Two Torus" with the suggestions.. Yeah, we all get excited and loose traction at times...


01-16-2012, 01:42 PM
Pain meds and muscle relaxers.. Go figure! :rolleyes:

01-16-2012, 02:06 PM
Thanks, Ed. That means a lot to me. One, because you are the true inventor of the concept and two, because I was worried that you may have been offended by my using the concept. I will never make and sell them and, of course, mine will never be the simple elegant solution that yours is. If, in the future, you wanted to build and sell more complicated jigs, I think it would be a good thing. I would be happy to give you everything I come up with. I think your operation of making and selling jigs is a great thing for both Carvewright owners and LHR. I hope it will continue.

01-16-2012, 04:43 PM
bergerud,I do really like the Rotary you have come up with. It's a shame that shipping is so high to Canada, I have a Big Box (probably 40) of 8 inch long 2" maple and birch dowels that don't fit anything that I have, but my wood lathe. And, one can only make so many wooden bullets before it gets boring. These pieces are a by product of the 36" dowels I cut into 14" lengths. With your Rotary that wouldn't be a problem.
Anyway, the Rotary you have would have many more uses than mine. It's a pleasure to see improvments in something that I had a part in.
Thanks for the compliments..

Ed Baker

01-16-2012, 10:45 PM
Big Ups to Both ED and DAN !!!! In any case, Great job by both of U guyzzzz !!! Reminds me of an old Sears spiral crafter... Except that these are automatic and U don't have to stand there turning a crank and adjusting ur router...

01-18-2012, 11:50 AM
Kevin has emailed me asking how the jig measures the dowel. In case anyone else was wondering I thought I would post the response I gave him.

The jig has two positions, it slides back 1.5 inches to put the dowel under the board sensor. First the machine measures the width just like it was a board. Note the black marks to make the sides invisible to the board sensor. After the width is measured, the x starts rolling to look for the end of the board. There is a slot in the driver rail that a bearing attached to the roller lifter rolls in. The slot drops near the end of the driver rail so that the roller lift drops the left side of back roller and the machine thinks the board edge has passed. The board sensor is now in the middle of the dowel looking for the end to pass as the dowel rolls. A strategically placed black felt pen mark or strip of black electrical tape now tricks the board sensor into thinking it has found the end of the board. Since the choice was made to place on end, the measuring is done. Time for the bit. The machine goes through the dance with the bit and then (since the default touch is set to jog to touch) stops for the jog to touch. The jig is now slid forward to put the dowel under the bit, clamped down harder and, enter is pressed. The bit touches down on the dowel and the carving begins. (Of course it matters not where carving starts!) There are still some small details and problems but that is about it.

01-18-2012, 02:25 PM
Many years ago I used to "carve/turn" ropes with my Sears "Router-Crafter". You cut a little at a time in 3 spirals until the 3 slots meet in the middle. You have 3 spirals and hollow in the middle. Do you suppose a rotary jig could do this?

01-19-2012, 01:03 PM
I am not quite sure what you mean. If you mean three spiral strands with gaps between them, I think it is possible. The dowel diameter would have to be fairly small so the bit could reach the back of the strands. Strand thickness + 0.8" or so and there would have to enough room for the bit between the strands. I like it. I will work on it. Good idea.

Edit: actually this is really interesting because the carving bit could go past the center of the dowel. Hummm..

01-19-2012, 02:45 PM
Having worked with this concept with a 4 axis machine, yes it is possible. The MPC would have to be line/vector drawings with bits assigned to each line. I wouls suggest a .15 or .2 max depth of cut per pass in order to lessen the pressure on the jig. Also, I would also have the stock hollow to start so the bits will eventuallt cut into a void in the middle of the blank. We do this on the Legacy by using stock that has had a 1/2 round slot (1 inch radius bit cut 1/2 inch deep) on flat stock. The two pieces are then glued together and the exterior is rounded to the desired radius. This is then mounted on end holders that have a 1 inch radius pin in the middle for alignment.

This along with a MPC with either reliefs or vector carvings that pierce into the hollow centers would create very interesting projects. I can provide a link to a CNC site that would show the concept much better than I can explain if anyone wishes.

edit: Added picture of concept.


01-19-2012, 05:16 PM
I am not sure we are thinking about the same thing. Here is a simple way to ask the question: what kind of crankshafts can I carve? How far of center can I go with the crank and still be able to carve the back and sides? When carving past the center to the backside, the wood changes direction. I have figured out the math to unwrap a surface to the "flat" surface to carve. Going past center, however, is a whole new story. I thought before about carving a chain and decided that it was not really possible. Then I mapped out the two tori instead. So much for working on the jig, now I have to think about this!

01-19-2012, 06:11 PM
Can I carve something like this? I think this is what cestout was talking about. Boggles my mind if you want to carve the backs of the ropes through the gaps.

01-19-2012, 06:38 PM
That is exactly what I was talking about, but shallow passes and the correct wood are important. When I did it with my router/crafter I tried it twice with poplar (short grain) and it exploded both times, then I used doug fir and it worked great. Maybe by the time I can afford this contraption, the new ideas will have been incorporated.

01-19-2012, 06:48 PM
Go to this link http://www.legacycncwoodworking.com/project-videos/?currentPage=3 and watch Part-1 and Part-2 to see the concept.

We may be thinking of apples vs. oranges but with a little imagination a CW rotary jig can do this and have hollow center parts.

edit: I just saw your post above. You don't have to carve the back side to get the hollow. You could use a 2 flute straight cutter and try to go to a depth that is equal to the radius of the part but that would limit the size of the part because of the plunge limitations of the CW. Using hollow stock like shown in the videos emilinates this. The only limitation now is the thickness of the carve to the hollow point which would be the max plunge depth (.808).

01-19-2012, 08:49 PM
I watched the videos. There is no problem to do that. The cutting only went as deep as the center hole. As long as the difference in radius of the dowel and the hole was less that 0.8" for carving or 1" for cutting, I do not see a problem.

The interesting problem (sorry - geek here) is to carve through the gaps to carve the back of the other side. To end up with spirals that have a circular cross sections. Of course this will severely limit the size of the thing but, I think it can be done.

That Legacy machine looks pretty cool. (A real 4 axis not just x traded for theta like the rotary jig.). I cannot say that interface looked very user friendly!

01-19-2012, 09:10 PM
I think he means something like these pics. They were common projects using the sears router crafter. I have one that I still have never used. I do want to use it one day.

http://lumberjocks.com/gdpifer/blog/22918 (http://lumberjocks.com/gdpifer/blog/22918)


01-19-2012, 10:51 PM
The Legacy can do those too. I used the hollow method as an example because of the CW Depth of cut limitations. I do remember the Craftsman. I really wanted one of those but couldn't afford one.

The software for the Legacy is Mach3 and you control it with GCode. The CW software is MUCH EASIER!

James RS
01-20-2012, 08:44 AM
I bought a Sears router crafter off ebay recently haven't had a chance to use it yet. Also wanted the rotary jig for my cw

01-23-2012, 09:39 AM
Somebody needs to think of turning the dowel the other direction to make 3' long table legs. Make a 4" square box x 3' long ,add the same kind of motors that are used now in the CW at the end of the box to turn the dowel. Hook the motor to the same port as the probe , so it turns the dowel while cutting it.
Give you engineer guys something to think about.
later Daniel

01-23-2012, 10:34 AM
I was thinking the same....

01-23-2012, 10:48 AM
Maybee Carvewright will introduce a dedicated 3 axis router lathe they are hard to find.

01-23-2012, 11:01 AM
I have put some thought into just how to have the dowel axis along the x. It would have to be turned by the y motor. That is, the dowel would have to roll left and right following the carriage against rails above the dowel (not on the sandpaper belts). These rails would have to be at the ends of the dowel which may be far outside the machine. Seems to me to be very difficult, and, it would be very hard on the y motor.

I think that four (or more) sided carves may be the way to go with table legs.

01-23-2012, 06:22 PM
I have one CW machine that is HIGHLY modified, that will carve any "reasonable length" round stock from 1.25" up to 5" in diameter. By reasonable length, I mean something under 8 foot. (due to my small shop) It, however is limited to carving only 14.5 inches of the stock at a time, then the carve has to be restarted. It is capable of carving oval pieces too. And, even with all of the modifications I have made to it, it will still carve flat boards like it did when it was new. I could not recomend that anyone do those mods to a machine because all of the safety features are missing, and the machine now has no covers or shields. But, It can be done with a CW machine..