Info on picture from shopbot camp

[myxpykalix]

This pic was from the seattle campshopbot on this link:
http://www.flickr.com/photos/campshopbot/214928120/in/set-72157594236388106/

Does anyone know who did these? Are the files to make these available anywhere or something someone made?

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[gwilson]

Jack,
I also would like to know. I also wonder if there is a basic math formula to help figure rotation speed and x axis or y axis (depending on your set up) movement and speed. I know you would need diameter, overall length of piece, amount of twist per inch, but that is as far as I get. So I would like to hear what everyone else says or is doing to calculate and make these.
Gerald Wilson

[fleinbach]

I to am interested. Maybe it will give me incentive to hook up my indexer I purchased last year.

[myxpykalix]

hello gerald,

Here is what i know from using my legacy ornamental mill for the same basic thing.
Pitch=the length in the X axis router has to travel to complete one rotation of the stock.
You use that in conjunction with the type/width of bit and gearset to determine the type of design you get. To get a better explaination of this go here:
http://legacywoodworking.com/technique.cfm?techniqueID=7 and other techniques there. I can do rope twists, barley twist, hollow spirals, ect.

So for example to do a rope twist, We call that a "3 start" spiral. I use a 1" rope molding bit. The gearing will take the carriage down the X axis 3" in one revolution of 1" round stock. So now router travels to end of stock. I release carriage from leadscrew and move it back 1". Reattch to leadscew and rewind it to starting point. Run router down X axis for a second pass. Repeat operation for 3rd pass. This creates the rope pattern in 3 passes around the diameter of material. Translating that info to a formula for a shopbot file is beyond me at this point. I have an indexer do you? I haven't set it up yet though. The shopbot control software has a section for making spirals on the indexer control. It looks as though you can plug in the info you want to make your spiral pattern (if you know what it is), thats why going to the legacy site might give you some background on pattern/bit size combinations that might help you understand a bit more. If you learn more please let me know via email and i'll do the same.

[bill.young]

Jack's right...if you have one of the special rope molding bits then you can use the Indexer Virtual Tool to create rope molding. It will talk a little figuring because those bits only work if there's a specific spacing between "ropes" and that can vary with a bunch of variables...the blank diameter, the number of times each rope wrap around the blank, and the number of ropes.

It looks like the ones in the pictures weren't done with one of those bits though. In the DOS days when you bought an indexer you got a floppy disk with a couple of example files, and they included files to cut a single and double helix with a small ball-nose bit. They were pretty tough to cut successfully because after a while all you had was short-grain and they tended to break before they were finished cutting, but if someone wants to experiment with them I'll update them to work with the Windows software and stick them in ShopBot Labs.

Bill

[gwilson]

Thank You, I am really starting to understand this better. With the info from legacywoodworking info, Jack and Bill's info it is helping alot.
Gerald Wilson

[myxpykalix]

Yes bill please update them and let me know. In the meantime i can get the sizes and links and pics for my bits and some other "formulas" from my legacy project book and post. I also have some BIG full size pattrens for several different spirals i could try to copy for you. Here is a couple pics of columns i made with a 3" spiral bit.


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[myxpykalix]

Bill...FYI..here are a couple of pix of rope moldings i did. rope1 is a pic of a 1" rope molding bit. If you notice the bit measures 1" from "peak to peak", then follow the formula above for 3. In rope2 you see on bottom a left hand spiral on top a right hand spiral. To accomplish the hollow spiral you take a 3/8 bit (or 1/4") I forget..and center it on the valley and cut in to the center

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[larry_r]

I have just finished mounting my indexer and would like to make the hollow spiral in Jack's picture above. What kind of wood is best for this type of design?

Jack or anyone else with the Lagacy machine, how long would it take to make the hollow spiral above on a Legacy Lathe?

Larry

[myxpykalix]

It would take about 5-6 min on a legacy. But that is more manual because you have to do it in 3 passes to make the rope bit, then take a 1/4 spiral bit and go into the "valley" part of the design to do the hollow. Since i've not done any on the indexer, i don't know if it has to use the same "formula" to create the ropes (that being in 3 passes) since with the legacy you are dealing with a leadscrew (4 TPI) and different gears on the headstock. I posted a pic of the headstock and gears (but forgot what heading it was under, search "Legacy" should find it).
Since the indexer is controlled by a stepper motor instead of a leadscrew that is attached to specific gearing seems to me your designs would be far better (only limited to bit size). I would think the shopbot could do that pretty quickly, I bet Bill Young could shine some light on this subject...bill....bill...BILLLLL! you out there??
lol