Spirals

[btboone]

Wow Fred, That helps. I was assuming 1/2-13 or so. The smaller pulley can be larger with that.

 

[Fred in NC]

Sewing machine belts don't stretch as much as o-rings, which are by nature flexible. I have seen them for about a dollar. They will probably need an idler to take slack when changing ratios.

ADDED: Eureka vacuum cleaner belts are the same as used in older sewing machines. Cheap!

 

[btboone]

There are also those tiny toothed belts that would also work great. I think the pulleys for those are relatively expensive though. I haven't sourced any so I could be wrong on that.

 

[JimGo]

Bruce,
Do you think we could make something with adjustable jaws, like a self-centering 4-jaw chuck, so that the operator could adjust the size of the drive gear? That would allow the operator to almost "infinitely" adjust the helix.

 

[Fred in NC]

Bruce, I have priced them. Not cheap!

Also, poly-v (serpentine) belts provide a lot of traction. I buy them for Jet Mini and they are inexpensive if you get them from the source. The pulleys are a different story, have not found them !

 

[btboone]

Jim, anything is possible. If the constraints are to be making a machine that's in the range of, say $25, then we might be pushing. I was originally considering a machine that would create a single spiral with a fixed pitch. It could be changed over by changing pulleys, but adding on any capabilities will add complexity and cost as well.

 

[Fred in NC]

Ah, Bruce !!! If the design uses a FLAT belt, like the vacuums, then there is no problem !!!!

Anybody with a lathe can turn a pulley for a FLAT belt !!!!
Then we can have whatever pitch we want. Even hardwood will work for a pulley. It might need an idler to take the slack, that's all.

 

[btboone]

I agree Fred. They would just need to make different pulleys though. I don't see a way to be able to change pitch easily without changing out those pulleys that doesn't add a lot of complexity like variable speed drives and such.

 

[btboone]

The idler also has the advantage of being able to be used to creat multiple start helices. One would be turned, then the spindle would be locked and the idler loosened. The nut driving screw would be advanced without the pen turning, then the idler would be reengaged.

 

[Tom McMillan]

Really sorry guys---but I've just got to say I'm salivating over all of this--all of your expertise is almost too much---WOW--- " SPIRAL MACHINEP" can't wait to see what you all come up with!!!!!!!

 

[Fred in NC]

Well, first of all, thank you Tom for your kind comments! Paul and Bruce are experts in the machining field. I am not an expert at anything, but I like to contribute whatever I can to a project like this. I call it brainstorming.

There is a lot more to it than experience. The word ex-perience implies knowledge from outside sources and long time practice. Those who shine in their fields, like Bruce, Paul, and many others in this group, have an additional quality that does not come from experience. It is the ability to create new things. Some are beautiful, some are practical, and all are new. My hat tips to such people! Thank you for your contributions to IAP, the group, and the art of penturning.

 

[Paul in OKC]

There is a lot being said here about ratios and what not. I have a bad enough time trying not to turn my projects into rocket science[]
But to keep the price low, it will have to be a single pitch, I think. I also was thinking of acme rod like 1/2-10. 4:1 would be like 2 1/2 threads per inch. An idler would help give more ratios. I'm not sure what would be the most 'popular'. It would take some gearing down to make less than one spiral per barrel. I will check my sources for plastic gears and or timing type stuff.

 

[Scottydont]

I am interested in what the creative minds come up with here. I happen to have the new Legacy 200 milling machine. It is designed specifically to do pen type spindles. I bought it do spirals and I like using it to turn end grain cut pens that tend to have blow outs and do the final shaping on the Jet Mini. I have not used it too much yet. I am in the process of building a cabinet to have the Jet mini on one side and the Legacy on the other. I would be interested if it would be feasable to have different diameter gears cut on a CNC machine.

http://www.legacywoodworking.com/products.cfm?product=36

 

[DCBluesman]

I tried that machine for about an hour or so today and was not totally pleased with the results. I'll be pleased to see what your experience is, Scott.

 

[btboone]

Scott, gears are usually done on a hobbing machine, something that cuts gear teeth in a stack of gears that ends up looking like a corn cob. The more normal CNC machines won't do a good job of them since they would have to rely on a thin cutter cutting through thick stock. There would be breakage and chatter issues.

I'm unbelievably slammed with ring orders for some reason, something like 25 rings (around $8K worth,) so I might have to ask Fred, Jim, or Paul to draw up the initial stuff unless it can wait another day or two.

 

[Fred in NC]

Lou, I appreciate your opinion because I have been considering the Legacy too. Would you mind explaining what you did not like about it? Thanks !

Scott, cutting gears is possible of course. But one reason I was proposing flat vacuum belts and pulleys for our design is that we can easily make sets of pulleys with different ratios with a wood lathe. The pulleys would be just a wood or plastic disk with a recessed flat in the middle. Piece of cake!

 

[JimGo]

Fred,
I agree with you. I also think that this will pretty much be a necessity. What I was thinking of, and my understanding of Bruce's original design, was something that used a belt of some sort to attach to the drive spindle of the lathe. Since each lathe is going to probably have different gearing, or for the variable speed ones, different drive spindle size, I thought we'd NEED to be able to make our own gears. Bruce, I might be able to rough something out tomorrow, although I don't have CAD software (so it may be a little rough!).

- Jim

 

[DCBluesman]

Originally posted by Fred in NC
<br />Lou, I appreciate your opinion because I have been considering the Legacy too. Would you mind explaining what you did not like about it? Thanks !

Ok, but remember that this is just a one-hour trial (actually, I was demo'ing since Legacy's man was busy with the 1200).

I first visited yesterday and was disappointed by the fact that the machine could not be demo'd...No blanks, if you can imagine. The machine's mandrel is a 7MM and there are no options. I went home, grabbed some different species of blanks and cut/drilled/tubed them for today. Upon my return I was shown how to set up and run the machine. It is simple to use.

The first thing that struck me is that the design is built around the Porter Cable Model 7310 Laminate Trimmer. That means you have a 5.6 amps and a single-speed (30,000 RPM). The Laminate trimmer lists for $190 but can be found online for around $115. That's quite an expensive addition to the $359 for the Legacy Model 200.

Another drawback (for me) is that it turns left hand spirals, exclusively. That's not bad (necessarily) for pens, but is a real drawback in making salt/pepper shakers or candlesticks which should be spiraled to compliment each other.

The index wheel is 12-position (30-degree) with no options for change out. The spiral pitch is 1-1/2 inches, non-adjustable.

In turning pen blanks, I tried maple, afzelia, black and white ebony and rosewood. Blanks were between 5/8 and 3/4. I was turning them down to .030 inches, adjusted with a feeler gauge. I was turning a 1/4" spaced repeating spiral, requiring 6 passes to cut the spirals. Six passes is not undesirable, since they go quickly, but I soon found out that the combination of motor amps, RPM's and depth of cut made it impractical to cut each spiral in one pass. Instead, each spiral requires two passes (maple) to 4 passes (black and white ebony) to complete the spirals (that's 24 total passes for one set of blanks). FYI, the B&W ebony and the rosewood were 5/8".

Of a dozen blanks turned, only 4 turned without serious chipping or full blow-outs. This may be due to have an old cutter. I have no way of knowing. Of these blanks, all will have to be buffed significantly since the surface is too rough (for my standards) to begin finishing.

Overall, I think this machine grades out at a B-. In considering the price, Probably no better than a C.

I hope I'm wrong about this machine. When others who have purchased the machine get use to it, they may find that my one-hour test was not indicative of it's abilities. I'm open to being wrong on this one.

 

[btboone]

Jim, what I had in mind didn't use the lathe at all. It would be a free standing 3 sided box maybe around 8" long x 4" x 4" deep made from wood or plastic with maybe 3/4" walls. The pen would be mounted on a 1/4" allthread rod and secured with nuts. The threaded rod should fit within a 7mm brass bushing of a pen. The large pulley (just a turned cylinder around 2" diameter and maybe 3/4" thick) would ride on that shaft and some nuts would lock it in place. Above and to the left of the pen shaft would be the nut driving shaft. It can be the 3/8-8tpi acme thread that Fred was referring to. Another pulley, this one much smaller, like 1/2" diameter is locked onto this shaft. This shaft is the one that extends through the wall and has a handle on it. The nut is attached to a wood or plastic carriage that the Dremel is mounted to. The carriage is only supported by the nut, so is free to rotate about the axis of the shaft. Rotation is stopped at the centerline of the pen shaft by another wall of wood or plastic that the carriage can scoot along. The Dremel cutter would be engaged into the pen when in this position. There can be a screw that acts as a depth adjustment on the bottom of the carriage.

In a nutshell, that's what I had in mind.

 

[Fred in NC]

Thank you, Lou. Appreciate your candid comments.

A laminate trimmer might not be the best tool for routing pens. The wood is rather thin for that. Also, I dislike the idea that it is not very adjustable, has a lot of limitations. The $500 investment for that seems to be very high for me.

Back to the drawing board!!

 

[JimGo]

Thanks for the clarification Bruce!

Lou, thanks for the review, and for taking the time to do the great finishing write-up!

 

[Fred in NC]

Bruce, your idea is very simple !!! And simple is EXCELLENT in my book ! Very few parts makes it simple to build and adjust.

Now, if we could get hold of an ACME tap to match the rods, we could make some nuts from delrin or similar plastic. My idea is to make a long nut, so it engages 12-16 threads. Less wear and less backlash. I did not see a tap for this size, but somebody must have it. The ACME taps are expensive !! Probably $50 or so for this one. Whoever buys the tap should sell the nuts to cover his cost and labor. I am not sure about making them with the CNC because of the square valleys in ACME threads.

Let's keep brainstorming, soon we will have a design to try out.

 

[btboone]

Fred, I was thinking to buy an acme nut and press fit it into an undersized hole in the plastic. It can then be setscrewed in place just to be sure. The other end of the hole can simply be a 3/8" hole to ride on the outside of the threads.

 

[DCBluesman]

A picture's worth (more than) a thousand words. Here's some samples. The burns are avoidable--sometimes--but it may mean a few more passes with shallower cuts.

<br />

Originally posted by DCBluesman
<br />Of these blanks, all will have to be buffed significantly since the surface is too rough (for my standards) to begin finishing.

 

[Fred in NC]

Bruce, that might work ....

The reason for the plastic nut is this: a slit can be cut along the axis, and used to compress the nut to control the slop. Of course, some backlash is not a problem when you are turning the shaft in one direction during the cut.

 

[JimGo]

Lou, thanks for the pics! Those are surprisingly rough!

 

[woodscavenger]

You guys lost me on page two with the technical mumbo jumbo. Keep at it though. I would love to see a sketch. My brain can't wrap around what you are trying to build. For now I will stick with my hand cut method.

 

[JimGo]

Shane,
your pens come out great, so I don't blame you for wanting to stick to the hand cut method. This is a way for those of us without our steady hands and skilled artisanship to cheat!

Bruce or Fred, do you guys know of a decent open source or free technical drawing program? As an EE, I don't usually need that kind of software!

 

[Fred in NC]

Sheesh, Lou, not what I would expect from a $500 setup. Maybe the router bit is part of the problem.

 

[Tom McMillan]

Wow, Lou---Thanks for sharing that---Guess, for now, I'm best to continue with my hand spirals too---but, I would think there would be a way to get a smoother cut with that Legacy. Maybe Scott will do some work with his, and report on the results----Others here have Legacy's and made spirals---seems I've seen some???? Successes---failures???

 

[btboone]

Jim, there's an excellent one called Rhino (www.rhino3d.com) which has some nice software that can do 2D or 3D. (It could actually draw the shapes that Lou posted.) The full working version can be downloaded for free for you to try. It saves only around 15 times though. The software is relatively cheap for as powerful as it is, and students get a huge break on price. I have seen a couple others that are free downloads, but I can't think of their names at the time.

 

[DCBluesman]

I let JR Beall's buff along with a load of tripoli and white diamond work for a while on these.

<br />
I doubt these are going to see even a 24k slimline, though. The Model 900 can produce some exceptional pens, but at $1,300 it darned sure should! This machine's technology is much different.

Also, for $400-500, how many spiral pens would I have to sell?

Truly, though, I hope Alice and Scott show that this was an aberration. [8D]

Originally posted by Tom McMillan
<br />Wow, Lou---Thanks for sharing that---Guess, for now, I'm best to continue with my hand spirals too---but, I would think there would be a way to get a smoother cut with that Legacy. Maybe Scott will do some work with his, and report on the results----Others here have Legacy's and made spirals---seems I've seen some???? Successes---failures???

 

[ctEaglesc]

I have been reading this since 4:00 this morning and was wondering something.
Instead of buying taps and dies and gear ratios and all that stuff.
Here's where my uneducated thinking comes in,
Would it not be easier to modify a large C clamp to hold a Dremel tool?
The treads are already cut.
As you "screw" the C clamp it would advance the Dremel with whatever size bit you would need.
It would seem you could make a set of pulleys and a windlass arrangement.
Car jacks,house jacks, C,turnbuckles clamps all use Acme threads do they not?
For less than $20.00 you have the male and female parts and you are not doing all the tooling.
If I'm missing something as to why this would not be easier let me know.
(Great now I have something to think about while I'm getting ready for a "Sportsman Show")

 

[Gregory Huey]

Lou
Thanks for the pics, I am now going to think about this machine a little longer.

 

[Paul in OKC]

Originally posted by Fred in NC
<br />Bruce, your idea is very simple !!! And simple is EXCELLENT in my book ! Very few parts makes it simple to build and adjust.

Now, if we could get hold of an ACME tap to match the rods, we could make some nuts from delrin or similar plastic. My idea is to make a long nut, so it engages 12-16 threads. Less wear and less backlash. I did not see a tap for this size, but somebody must have it. The ACME taps are expensive !! Probably $50 or so for this one. Whoever buys the tap should sell the nuts to cover his cost and labor. I am not sure about making them with the CNC because of the square valleys in ACME threads.

Let's keep brainstorming, soon we will have a design to try out.

I was thinking along this line as well, Fred. The only acme taps I have seen start at 1/2-10, and they are around $50. Bruce, your idea is definately a good way to keep it simple as to the carriage. I'm not sure about stability though. I thought about the carriage being on two rods with the screw in the middle. This of course takes more machine work which makes the cost a little more. I'll see if I can get some time to draw up some thing as well. Looking forward to this 'collaberation' project[]

 

[Fred in NC]

Paul: I think the reason for Bruce's design is that it will simplify raising the router out of the work. It will not actually rise, but swing out of the way. At any rate it looks like we need to be able to control the depth of the cut.

As for the plastic nut and tap, I have found that plastic give a little bit when tapped, and the resulting threaded hole is more accurate, ie. tighter. Enco has taps like you said for $50.

 

[J. Fred Muggs]

<br />


Alright, I apologize for the picture size.

What if I told you this was done with a hand held, non-motorized, almost like a chisel, powered by the rotation of the piece in the lathe, sells retail for $150 list, comes with the ability to do three sizes of cut, variable pitch, left or right hand, CD included, etc. etc.????

Would you be interested???

It's known as the Robert Sorby spiralling and texturing tool.

It works by simply engaging a gear-like cutter with axis of rotation of the cutter somewhat perpedicular (but at a slight angle) to the axis of rotation of the workpiece. This angle causes the cutter to rotate. by then sliding the cutter along the length of the workpiece, you create a spiral cut in the workpiece. by angling the cutter to the left you create a spiral that runs right to left. Angle it the other way, it runs left to right. The angle at which you present the cutter to the workpiece determines the pitch of the spiral. To create a checkering effect like the pen above, you cut a spiral in one direction, then a second spiral in the other direction.

The checkering above was done using the smallest pitch of the three supplied cutters. Also the piece was sanded heavily after cutting because I wanted a checkered look as opposed to just a spiral.

Due to time limitations I have not had much opportunity to play with this tool. It does take some time to master. Additionally&lt; I didn't get the free CD when I bought mine. But did get one just about a month ago. Honestly, so far, this is the only pen I consider salable. But then, I've only tried about four, so far. I bought the tool more for faceplate useage. You can see a sample of that in a pocket watch case in pink ivory in my album. The best efforts of that were sold before I could get pictures.

Take a look at http://www.robert-sorby.co.uk/ under woodturning tools/spiralling/texturing system.

My experience so far: It does not work well in softer woods that are prone to tearout. The pen above is tulip wood. It does require some practice to master (I do not claim to have come close to mastering it yet).

Go to this site http://www.carolinamountainwoodturners.org/ click on Michael Mocho/ August 2005 under demonstrations at the top left and you can see Mocho using the tool in both spindle and faceplate applications. It was this demo that conviced me I had to have one.

The tool itself is little more than a gear with a ball bearing held on the end of a turning tool. I'm confident Bruce and probably many more of you could make your own for twenty bucks or so.

There are, indeed, alo of ways to make a spiral. This method, you could legitimately says is still "handmade" as much so as using any other tool in conjunction with a motorized lathe. It's less expensive to buy retail than many of the other spiralling systems. And, from what I see in this thread sofar, It really oughta get all your thinking caps really buzzing.

 

[darbytee]

Fred, I've got one of those Sorby spiralling tools that I haven't even used yet. It was given to me by the guys at my local Woodcraft in compensation for doing a demo and helping out with their Freedom Pen Turnathon. I want to go play with it now!!

 

[btboone]

Fred, I've never tried them on wood, but a knurling tool for a metal lathe does just that pattern. They are usually quite a bit cheaper, like in the range of $20 to $50.

 

[btboone]

Fred, I've never tried them on wood, but a knurling tool for a metal lathe does just that pattern. They are usually quite a bit cheaper, like in the range of $20 to $50.