[brouser1]

Sorry if this is posted in the wrong section. I searched, but didn't find exactly what I was looking for.

I am hoping people can discuss/or give me a few pointers on your approach to designing a "part" to be cut. For example, someone asks you to cut out "x-part" for you. If it is small enough to fit on your scanner, do you scan it? If it is bigger and heavier than what would fit on your scanner what do you do? What is your approach? Do you print out your over-size designs before cutting?

I am sure this is very very basic for a lot of you, but I haven't worked with anyone that uses a Cnc Plasma or any other Cnc system.

Thank you for any and all info in advance.
Eric

[Torchhead]

Depends on how complex the part and how accurate you want it. There is no easy way to do one-off parts. If you are good at CAD or the drawing software you use you can usually take some dimensions and draw it on the screen pretty fast. If it's decorative in nature and it''s to big to scan and trace then a digital camera shot (important to be a 90deg shot to the object) can give you something to trace then take the vector result and size it by measuring the original. It's difficult to make money doing reproductions of a part unless you can sell more than one. Even if you are good at the drawing it can take 30 minutes to get usable artwork for a simple shape.

You will have all kinds of "work" show up at your door once people know you have a CNC table. If it's a friend do it for free and go on. If it's a stranger be nice and plesant but explain that you can cut them one or 10 for about the same price because of the setup time. Go to a printer sometime and ask them for 10 business cards. (:-)

TOM Caudle
www.CandCNC.com

[brouser1]

Thanks Tom!

I appreciate your input & advice.

Everyone else, please post your workflows or thought processes in your design approaches. I see a lot of people have viewed this thread, so there must be more interest. Post your $.02. Since I am new, most all info is helpful.

Thanks again Tom.

Eric

[jimcolt]

I do the occasional jobs to help support my home based shop. I have a few customers that send me .dxf files.....that makes life easy for me as far as cnc cutting goes. In many cases, however....the customer may also be a hobbyist with no cad drawing capability. In these cases I will have them fax or email a sketch or bitmap of the part they want cut.....and I will draw it myself.

I think the key to the success of a small cnc operation is in the mastery of a CAD drawing system. Most sketches I get from customers can be cad drawn in less than 5 minutes. With my rates.....that's about $5 worth of my time....and in most cases it can be easily tacked on the cost of the part that requires cutting.

Typical jobs that I have done: Suspension brackets for race cars and 4 x 4's, agricultural equipment parts such as gussetts, brackets, parts for structural steel-levelling plates, architectural brackets, etc.

The key to processing CAD drawings quickly? Find a drawing package that is entry level, windows based...and comes with a tutorial in print. Practice, practice, practice. In a few months time you will find that CAD drawing is not a chore....and is actually kind of fun and satisfying....especially after you cut the finished part!

I learned CAD with the PlasmaCam software.....it was very easy to learn, easy to use. Today I can use other packages....but when I need to draw simple parts fast...and get them done quickly....the PlasmaCam is my first choice.

This weekend I had requests for parts from two different sources.....one was a bracket for a zip-line trolley that needed to be cut from 1/8" carbon steel and 3/16" carbon steel.....the customer sent me a .dxf, I looked at the drawing on my office computer, saved it on a USB stick, walked out to my shop and had the parts cut and ready to mail in less than 1/2 hour.....material cost was less than $6, selling price (not counting shipping) was $90 for 8 parts. Later in the day I did two suspension brackets out of 3/8" steel......I drew the parts from a hand sketch....5 to 10 minutes, then went to the shop and cut the parts (about 15 minutes with material handling time)...material cost of about $5, selling price of $56. I did a little more work later in the day (built a set of tractor bucket forks) that sold for $330......1-1/2 hours work (welding and cutting)...$105 material cost.

So....in about 2 hours (maybe a little more) on a Saturday I contributed close to $476 to my shop fund....without trying too hard. If I hadn't mastered tha CAD drawing part....I would have spent many more hours in the shop doing layout work to get the same parts out.

Picture of tractor bucket forks attached! Note: the forks are a standard product for me....so the design work was all done....just punched up the files on the PlasmaCam.....cut all the parts (a little bit of horizontal band saw work as well!) welded them up, squirted with Rustoleum. The clamp mechanism on my tractor forks is bandsawed to length, then put in a fixture on my cnc plasma and the slots and side bolt holes as well as the top hole are plasma cut to tight tolerances.

Jim Colt

[brouser1]

Great!

Thanks Jim.

[millman52]

I am in the middle of a job that on the surface really don't look like much to build. It is a stand from a private owned water plant.

The problem is I had none of the old stand to work with Literally fell apart from rust.

There is a pump & a motor that are coupled with a lovejoy type motor coupler. The shaft height of the motor is different from the pump

This is a 1 off job that will have a total cost of somewhere around $500.00-$800.00 because it will take several hours to calculate the differences in shaft mounting height, there will be 7 different pieces that will have to drawn in CAD But only about 2 hours total of cutting, assembly & welding.

Point being You have to charge for CAD or engineering time on 1 off parts.

[jimcolt]

Milman.....you always run into those jobs where you spend more time designing....less time doing the work. Trouble is....the customer doesn't like to pay for the design time! I have kind of learned to avoid that type of job...unless there is a way to bill the time. Most of the simple gusset/bracket jobs I do take literally 5 minutes or less to draw and upload to the cutting machine.

The forks that I show in the pic......I built a set for myself a few years ago.....I actually spent many hours and built 3 sets before I liked what I built! I could have bought a set from Northern Tool for less money.......however, now that the design work and drawing is done.....and welding jigs are built.....I can bang out a set in an hour. When I build them in batches of 10......I can do 10 sets in 8 hours. I have sold over 40 sets of forks locally.

So.....if you have to design and draw stuff.....make sure you 1. draw it fast, or 2. can bill for that time....if not, make sure it is something you can use many times in the future...like the tractor forks.

Jim

[millman52]

I quoted not to exceed $800.00 on the job figuring the price would scare them off... It turns out the company they purchase pump repair parts, chemicals etc. had already quoted then near double what I did.

I figured there the pump company was probably farming the job out to someone like myself then marking up the work.

I really have to be careful with jobs like this, as I am really a production shop not a job shop. If not careful these jobs will really get in the way of production.