Is there a cheaper machine that I can use, besides an Engine Lathe????

[zac penn]

I really do not need to do anything even close to fancy. My desired product is just plastic ribbon that will be shaved off of a solid 6" diameter plastic rod. My specs for the ribbon are .007" thick x 3/8" wide x infinity long! I know getting these exact specs are impossible to do by hand, so I need an automatic feed lathe that will cut .007" per revolution.

I am VERY new to lathes, and have been cruising around the forum for the last day or two and you guys are amazing craftsmen!

If you can point me in the right direction I would be very appreciative. Is there a lathes for dummies thread somewhere that explains what each part does, and what the different kind of machines do?

My budget is right around $1k - $1400 and i do not mind using a quality used machine.

Thanks a lot in advance,
Zac

[Ryan Baker]

It sounds like a metal lathe with power feeds would do the job, assuming you could find the right combination of feed rates. A CNC lathe would make it easy. Is this a one-time job or something you want to do often? If it's a one-off or small run, it would probably be cheaper and easier to hire a machine shop to do it for you.

[Jason Hallowell]

I agree with Ryan, you need to look at metal lathes. Finding a decent metal lathe shouldn't be much of a problem within your budget either. I just saw an old southbend with lots of tooling sell for $1200 last week. If I were you I'd start asking around on the machinist and metalworking forums. There are a couple of good ones, but I can't remember the names off hand.

[Jim Underwood]

I just gotta ask...

What are you going to do with .007" plastic ribbon?:confused:

And yes, I'd say that a metal lathe might do the trick, but how accurate do you need it to be? I would think that any plastic curled off of something like that will never be straight or even true. I could be wrong of course.

[zac penn]

Here is a picture of the ribbon I want...
http://img.photobucket.com/albums/v171/everythingextreme/turnedatLindysmachineshop003.jpg

It is used in biological filtration systems in the koi pond and watergarden hobbies.

I had the above ribbon turned at a local machine shop, and it cost me $69 to fill that box in the picture. At those prices there would be no way I could sell the media to my customers.

I am trying to figure out what kind of machine I need, but it is a little overwhelming right now. My needs are so basic and simple that there has to be a relatively cheap machine that will make my ribbon exactly .007" x 3/8" Those dimensions are important so that the ribbon still have strength, but also giving you the most surface area in a given volume.

I am checking ebay and there seems to be some good deals, but nothing local, and shipping a 6000 lbs machine sounds really expensive.

Thanks for your help,
Zac

[zac penn]

Oh I am also wondering if there is a way to keep the ribbon from spiraling into such a tight curl. I know that shaving small pieces off will create some curl, but it would be nice if it wasn't so tight. My thought is if the cutting tooth was tilted at a much higher angle of attach the ribbon would come off a little straighter...Am I correct in stating that?

[Chuck Saunders]

Yes you are correct Zac. The greater the angle and thinner the cut, the tighter the curl will be. Another factor will be the skew angle of the cutting edge to the direction of cut.

[Rob Cunningham]

The thickness of the chip/ ribbon will be dependent on the feed rate of the tool, the faster the feed, the thicker the chip. I would use a high speed steel tool bit. You'll have to experiment with grinding different angles on the top of the tool to change the amount of curl of the ribbon.

[Scott Loven]

I would try to find a place that machines plastic and buy their trimmings. You could probably find a plastics waste broker and see what they may have to offer.
Scott

[Bob Haverstock]

A couple of things,

1st. Consider cutting 2 or 3 three-eights blanks at a time.

2nd. Coolant might change the radius on the ribbons.

Question, is there a minimum lenght on the ribbons? Could you cut three-eights wide flat stock with a hand plane and a fence and achieve the .007 thickness?

If you machine shop coukd gang cut these, cost would go down.

Bob

[zac penn]

Wow thanks for all the responses.
I will be needing this ribbon on a continual basis, and it has to stay uniform all the time, so my surface area specs that my customers need will always be the same.

I understand the feed rate to ribbon thickness principle.

Can someone please take a picture of the cutting edge on an auto-feed lathe, so I can see what kind of adjustments are possible?

Zac

[zac penn]

A couple of things,

1st. Consider cutting 2 or 3 three-eights blanks at a time. I would be very happy to cut multiple 3/8" wide ribbons at once and have them intertwine together as they are cut. Is this a standard feature to all auto-feed lathes?

2nd. Coolant might change the radius on the ribbons. Can the coolant be just standard water? Since this media will be used in aquaculture applications it can't have any kind of chemicals used as coolants. Will the coolant really control the spiral of the ribbon more than the angle that the cutting edge is set to?

Question, is there a minimum lenght on the ribbons? Could you cut three-eights wide flat stock with a hand plane and a fence and achieve the .007 thickness? There is no minimum but having long lengths is best to keep the ribbon bunched up together. I may have to try this and see what I get as a result. However do not currently own a hand plane so experimenting with that would be an expensive gamble. Do you guys know anyone that could test this out for me real quick one night and take a picture of the resulting ribbon?

If you machine shop coukd gang cut these, cost would go down. That is true, but the costs will not go down enough to make it profitable. This has to be an in house operation for it to work.

Bob


Thanks a lot for all of your thoughts,
Zac

[Mike Spanbauer]

Zac, you're asking the right questions. I think you may be able to dig up more over at practical machinist.com though. The guys that hang out there are adept and most are shop owners or have EXTENSIVE experience with lathes and mills. I'd suggest a ping there (probably a question for the general lathe forum - there are LOTS of dfferent ones).

mike

[Reed Gray]

This reminds me of doing some concrete work in a plywood mill and watching them peel 18 to 24 inch logs in what seemed to be seconds. Since you would be peeling rounds, I wouldn't think you would want the cutter to be skewed, but that would work for peeling flat stock.
robo hippy

[Rob Cunningham]

Here is a picture of the tool bits I was talking about. You grind them to any shape you need.

[Jason Hallowell]

The thickness of the chip/ ribbon will be dependent on the feed rate of the tool, the faster the feed, the thicker the chip. I would use a high speed steel tool bit. You'll have to experiment with grinding different angles on the top of the tool to change the amount of curl of the ribbon.

I agree, playing with a custom grind is the best way to change the curliness of the ribbon. The feed rate will determine the width, the depth of the cut will determine the thickness.

[Jason Hallowell]

Attached are pictures of lathe cutting bits, and a pic of one in a holder. For a basic understanding of how metal lathes work, I suggest reading "How to Run a Lathe" from southbend. Metal lathes, even small ones, are very dangerous machines if you are unfamiliar with their operations. I would highly suggest learning the basics from someone experienced before cutting anything. Many community colleges offer machinists classes that can be audited very cheaply.

[Bob Haverstock]

Zac,

The biggest expense for this project in a commercal shop is clean up. First, you want your product clean, no tramp materials clinging to it. A very clean lathe is required.

Second, after you job is completed, especially is use as a coolant (water), the lathe must be cleaned dried and a rust inhibitor used . The complete lathe and coolant system must be protected fron rust.

I would think that the cutting tool would be positioned like the blade on a pencil sharpener. A tangent tool presentation would make less heat, possibly negating the need for coolant.

Bob

[Scott Conners]

I don't know where you're located, but here in socal I've seen a LOT of nice machine lathes going for cheap on craigslist recently. You'd probably need to spend some time cleaning and then learning to do what you want to do, but I imagine it's well within reach.

[Eric DeSilva]

Why a lathe? Is the curl a critical requirement? Why not just get rolls of 7 mil plastic sheeting and cut the rolls into smaller 3/8" rolls? Maybe you could even figure a way of causing the plastic to curl (heat?).

[Scott Lux]

Eric's idea sounds like the cheapest solution, as long as the plastic you want is available as sheet rolls. Many plastics are.
You could then slice the entire roll to 3/8" segments and voila! Instant curlies.

[zac penn]

The machining of the plastic causes millions of little divots in the ribbon that add to the surface area, and the curling action keeps the media intertwined. You really have to know about biological filtration in koi ponds to understand why I need the ribbons to be the way they are.

But thanks for the suggestions,
Zac

[John Fricke]

It seems to me in a lathe situation that you will end up with a lot of waste. The material being turned will need to be very ridgid to maintain the tolerances you are after. As it gets turned smaller in diameter it will be difficult to maintain the rigidity.

I would think some type of hot knife slicer would work better. You could stack several 3/8" sheets on edge and shave the edges. depth control and mecanizing the process are the obstacles.

[curtis rosche]

take a plastic rod. stick it in a hand drill. take a hand pencil sharpener and stick it in a vise. feed the plastic in using the drill. it should work really well. for longer ribons just use longer rods

[zac penn]

Once again a good idea, but it will not yield a uniform product!

I appreciate all of the help, but I think we can call this a dead horse. I am waiting for approval at the practical machinist and will be picking their brains next as to the correct machine for my needs and the best prices.

Thanks again for everyone help and patience.
Zac

[Scott Lux]

I hadn't thought about a film surface being too smooth, but it makes perfect sense in that application. We're used to trying to get a glass-smooth finish on a porous material :) No wonder we're thinking about it wrong.

Boy you are talking maximum surface area. That must make an incredible filter. I assume you've picked a particular plastic for its lack of toxicity and ph tolerance and so on.

Best of luck in this, I'm fascinated. But then I still use an old under-gravel in mine.