Cutting plastics / Prototypes

[wendell]

I need some help justifying the purchase of yet another ShopBot. I'm getting ready to move to a new high school and my boss would like to see us buy the following. (Page 12 of the following)
http://www.emco.at/pcmill_55.php?changelang=en

We'll be teaching an Engineering Tech class at the high school level an obviously need to simulate industry processes as closely as possible.
I can buy six ShopBots for the same money and I have been a customer since '91. Help me with some arguements as to why I should buy ShopBot again.
My short list includes:
Service and cost.

I can teach basic CNC skills but I can't cut threads

I'll need to cut plastics and perhaps alumnium due to the dust factors.
Other than buying a spindle are there any suggestions for lowering noise?
Our main purpose will be to cut prototypes of parts. (gears and other machine parts)

[billp]

Wendall,
Ask your new boss how much money they spent on signage at his school last year, and then point out how you can do most (if not all) of that work "in house"while at the same time providing a viable, real world, job skill for your students.
Show him the Shopbot Forum and point out that your students would immediately have access to this library of information, and assistance.
Point out that through Shopbot you can get a variety of "educational deals" on powerful software ( which you can run on a bunch of computers you've bought from the money saved by going Shopbot...).
Have him figure out just how many times a year he'll need to cut threads ( although this is also possible on a "Bot with certain software packages...).
In short, a milling machine does one area of production very well, but it IS limited. Have the boss look at the pictures of what Shopbotters are doing on our Flickr Camp page;http://www.flickr.com/photos/campshopbot/ and then let him compare apples and oranges....

[wendell]

Thanks Bill!

You made my day!

I thought maybe I've been wrong for the past 7 or 8 years. I've only bought four ShopBots and helped buy/install 2 others at schools.

I'll probably end up buying one of each (compromising) but we'll see which is tougher and used more. One challenge I'll have is quieting down the router. I know I can buy a spindle.

My other boss is really into PR. I think I'll drop the yard sign (that says Longhorns live here) by his office on my way home. And maybe make a new sign for our marketing teachers school store.

Needless to say you don't have to sell me!
I just need arguements for my budget meeting.

Thanks!

Wendell

[myxpykalix]

I can't talk with authority if you are talking about cuttting metal threads however I can cut spirals on my indexer and it is not a stretch to think you could make the rotations more with a smaller tool and cut threads usng a indexer.

Also I think using mach3 there are wizards for making threads and you can use the gcode on the indexer to create what you want.

[donchandler]

I cut threads all the time in plastic. I mount the rod vertical and go around it while spiraling down.
Threaded holes are a piece of cake. Use a thread cutting end mill that cuts one thread at a time, not the thread cutting end mills that look like a tap. I have even cut tapered pipe threads without any problems.

[wendell]

Thanks again for the comments! In the past I've used the bot for a prototype tool (and other things) to challenge kids to think. We cut everything from sleds to urns. We have bought expensive (inkjet style) prototyping tools but the bot gets used more due to consumable costs. Instead of depositing powder to form objects we merely take away material.
Has anyone built any sort of enclosure for a buddy? Noise is a huge consideration in my lab. I have neighbors who need quiet to teach.
Does anyone have a source for blocks of plastic?

[myxpykalix]

wendell...I think i saw this on ebay. I kept the pic because i thought i might get some of these. It looks like cutoffs from SIP panels. It might help insulate your sound.

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