Re: [CAD_CAM_EDM_DRO] Re: Retail, Low cost CNC

the crankorgan web site is a classic problem facing a CNC builder:

there are so many different needs of cnc machines that any one design can only hope to meet a small portion of the market. making several machines of similar construction but of different sizes helps satisfy cost vs. size issues.

during my research into the subject I have classified components of a cnc machine into 8 categories

1. structural: the rigid structural framework needed to provide accuracy
2.work surface: aluminum for lubricant drainage, clamping system vacuum clamping system, sacrificial layer

3. linear slides: provides accurate linear movement on x,y and z access

4 linear actuators: that which produces movements, worm gears, rack and pinion, belt ball screws, linear steppers

5 electronics steppers, wiring, servos, controllers, encoders, emergency stop switch, soft and hard limit switches, wiring, wire guides (for moving gantry)

6 software CAD/CAM, communications, converters (gcode from dxf file, tiff to cad file etc), control software (milling, foam wire cutters, engravers, Gerber drillers, development software (embedded controller , tool path optimizers)

7 accessories: tool changers, different spindles, lasers, vacuum clamp on/off,

8 AND MOST IMPORTANTLY!!!! GLUE. You might ask what does adhesive have to do with it? NOTHING. All of those off the shelf components you are putting together need brackets and hardware to hold it all together. A classic example would be a stepper motor has 4 holes that must be held at a distance from the end of a ball screw pillow block to allow room for a anti backlash coupler. This is the most costly and difficult element to deal with because you can�t buy it anywhere. It must be manufactured and must change each time the component suppliers change specifications, add products or if you find a cheaper component elsewhere.

Integration of as many design components into one structure is the key to designing a sellable machine at a reasonable price

Cheepcnc.com has a wonderful little machine that apparently uses a cnc machining manufacturing technique to integrate electrical, actuators, accessories, slides and work surface into one component by machining the material that is used for the combined work surface and structural framework. There is very little glue in the design but the materials are very expensive (as is reflected by the reported accuracy). The end result is a good quality product that costs 2 and a half grand for a 1 X 2 foot work surface

The question that is floating through my mind is does anyone have good ideas on other forms of integrating the elements together? And how much accuracy does a machine need to have for most light industrial and hobby uses? Is a thousandth of a inch needed for someone who is making fiberglass molds, model airplane components or musical instruments? Would a few hudreths of an inch do? what kind of durrability is needed for a "low end hobby" machine. obiously if you are shelling out a grand or more you need more durability than a black and decker but do you really need to run it 24 hours a day for several years on end like heavy industry?

jlsmith269 <jlsmith269@...> wrote:
and add 50% for lawyers and insurance...

www.crankorgan.com

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Boss" wrote:
> Figure on a wholesale price of at least 10 times materials cost if
you want
> a profit. Then double that price for the wholesaler will do it.
Double the
> wholesalers price for the retail price. Then do a test market at
the
> estimated retail price. If it will sell there OK, else forget it.
If it is a
> good seller, figure on orientals entering and competing with you at
lower
> prices or, move your manufacturing to Mexico.
> ----- Original Message -----
> From: "cnc_group2004"
> To:
> Sent: Tuesday, September 07, 2004 12:53 PM
> Subject: [CAD_CAM_EDM_DRO] Retail, Low cost CNC
>
>
> > My group and I are currently designing a low cost CNC gantry to
fit
> > common rotart style cutting tools (like the dremel type) for our
> > Senior Design class in Mechanical Engineering. We are currently
> > looking at the market and would be ever so grateful if we could
get
> > all your input on how this 'thing' should be designed (and if
> > possible sold later on). If you could send any comments on specs
or
> > things that are of concern to you (travel speeds, cost, accuracy,
> > etc) to CNC_group@h..., we would be very grateful.
> > :cheers:
> >
> >
> >
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
> > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
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> >
> > http://groups.yahoo.com/group/jobshophomeshop I consider this
to be a
> sister site to the CCED group, as many of the same members are
there, for OT
> subjects, that are not allowed on the CCED list.
> >
> > NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
POSTING THEM.
> DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> > bill
> > List Mom
> > List Owner
> >
> >
> > Yahoo! Groups Links
> >
> >
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> >
> >



Addresses:
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OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
http://www.metalworking.com/news_servers.html

http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.

NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
bill
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