How to Get the Best CNC Work from a CNC Company

How to Get the Best CNC Work from a CNC Company

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cnc machining

Are you looking at getting some cnc work done? Well finding a great vendor and making sure your final product is perfect can be tough. I’ve been through the process many times, so I’m going to help ease the process with my guide on getting the best cnc job done.

Here’s the 6 stage process from coming up with a file to getting an awesome cnc job done:

1.)  File setup

2.)  First communication

3.)  Negotiating on finish and price

4.)  Keeping tabs with the project

5.)  Building a quality relationship

6.)  Common pitfalls

Let’s touch on each. Please remember there is a comments section below, so if you have any queries or if you want some further advise on getting cnc work done, please feel free to ask.

So my background is in design originally. I have done a ton of drafting since and have crafted files for cnc cutting, cnc routing and rapid prototyping in many different countries including New Zealand, Dubai, America and China.

So I’ve dealt with many different vendors and while a lot of it can be straight forward, setting up the right process is critical. If you’re into business it’s like The E-Myth Revisited by Michael Gerber. In his book he talks about setting up a business with specific roles. You will be setting up a system here too, but for your cnc projects now and going forward. Here we go:

1.)  File setup


Alrighty so setting up your file is crucial. It’s hard for a cnc vendor to give you the right quote without the right file. You can send in an early file – but this is only ball-park, so I wouldn’t recommend this.

To get your file set up properly, I’d recommend getting in touch with some cnc vendors first, either locally/ overseas and asking what kind of file type they except. I’d say go with a .dxf if it’s for 2d cnc, or .iges / .stl file for export for cnc routing – but every cnc vendor is different.

You HAVE to test the file after you have exported it. Ideally exporting from one CAD program then re-importing it into another CAD program works best to ensure compatibility/ that the file is not corrupt. I suggest using a service like Dropbox, or for transferring larger files.

Key takeaways here: Make sure you know what kind of file type the vendor can work with, get it exported and given to the cnc operator as early as possible to get a quote.

When dealing with vendors overseas I always include a jpeg (screenshot) with a few key dimensions so that the vendor knows what the right scale it for the final output. I’ve heard of horror stories of files getting imported and the scale changing. To avoid this – include a jpeg and get the cnc vendor to verify.

2.)  First communication

cnc communication

By first communication I mean getting in touch with your cnc vendors. Crucial thnigs to remember:

There will always be a lead time – This is the amount of time it will take until the cnc vendor will be able to start your project as they may be busy with others.

Depending on the amount of cnc machines a vendor may have, there may be a large queue that you’ll have to wait behind. This is why you need to get a 3d/ 2d file (depending on the job) for a quote as soon as possible to see when your job can start and thus: when it will be finished.

Look for experience working with the type of material you will be using. If you are using resin or foam, make sure the vendor has worked with these. Ask for tolerences and bed size of the cnc machine.

The bed size will determine how big the job can be. If you are dead set on going with one particular vendor then I suggest splitting up the job into different files and gluing it/ putting it back together after.

You will also have to go for either a 3 or 5 axis machine depending on the project. A 3 axis cnc router is a lot cheaper, but you can’t do compound surfaces with a 3 axis router. Some vendors can move the project around and rout from different angles to achieve a similar effect to a 5 axis machine, but this has its obvious limitations.

Key takeaways here: Find a vendor early and decide either 3 or 5 axis machine depending on the shape of your project. Also ask if there are any specific tolerences; for example, etching vs cutting layers for 2d routing of aluminum plates.

3.)  Negotiating on finish and price

cnc surface finish

Surface finish is CRUCIAL. If you are into model making, then you are going to need a cnc machine that has a very precise machining tolerance.

CNC machines can go down to a fraction of a millimeter making it so you will not have to do any surface finishing – this will save a ton of time especially if the material is a tough resin or a type of steel that needs to be precise.

GL Model

Shop around for good pricing. In previous articles my favorite cnc vendor is GL Model in China. That’s because it’s cheaper for me to get smaller work done in China and finished exactly the way I want it to and then shipped to me than it is to get something cnc’d locally. I use GL Model for rapid prototyping too. Full  disclosure – I am not getting paid at all to endorse these guys. Here’s the article I wrote about these guys here.

Make sure you nail down the price using the exact file that you send a vendor. This is because if you change something on a file – typically this means adding more detail, then the price will have to be requoted as another cnc simulation will have to be run and this may increase the time it takes to cnc the new work depending on the new work paths chose.

Key take aways here: Make sure you see samples of finish straight out of the machine vs. after it has been finished. Also make sure you nail down price beforehand on the exact file name you give the cnc technician.

4.)  Keeping tabs with the project

cnc machine project snowflakes

Keeping tabs with the project is important, but there is no need to micromanage here. If you have done the groundwork already and you have the right contract, then you should be fine.

Always have something written or make sure expectations are set beforehand.

Non-cnc related – I once hired a model shop to paint some models I had cnc’d and they did a terrible job. I think it was due to me not having stringent rules that were agreed on beforehand and written and I was on a tight deadline.

Key take away – Lay a solid foundation on expectations – get this written down and agreed upon before work starts. Go for recommendations from people that have successful projects done from the vendor – but beware that every peoject is different and that one great experience and one terrible experience can come from the same cnc technician or cnc company.

5.)  Building a quality relationship

If your cnc company does a great job and delivers on time, then leave a positive review. You can use testimonials to help you choose a great company. The manufacturing niche isn’t too good at this, so the best example I can think of is the web design niche which I’m heavily involved in too. Here’s a good example of a site that uses testimonials to market – look for this in cnc vendors. It’s hard enough to find a great cnc technician or company. Cnc work is expensive so helping others using good testimonials to find a good one is crucial to help cnc consumers make an informed decision.

Once you have a few good cnc/ rapid prototyping vendors, then I highly suggest keeping the communication going as projects will always pop up if you are in the manufacturing industry.

Remember that cnc router machines and cnc lathes are getting more sophisticated and that cnc software prices and cnc machine training are going up – so don’t expect discounts all the time going forward – although it would be a nice bonus.

6.)  Common pitfalls

I think I’ve pretty much covered everything above, but here are some extras to help you get a kick-ass cnc project done.

-Never go with hand engravers

No offence to the talented out there – but nothing beats a machine for accuracy. I know sometimes given the shape of an object it may have to be hand engraved, but flat name plates should always be done with a machine to look pro.

-Always send a complete file

Pricing could jump when you send a lower quality file with less detail then send the proper one later. To avoid paying more than you were quoted – give your cnc technician a chance to quote you correctly with the right file.

-Always ask to see examples of surface finish done straight out of the machine (not finished up/ touched up afterwards)

-Always allow plenty of time

You limit the pool of great cnc vendors if you try and rush things as the best cnc providers always have some sort of lead time – typically at least 2-3 weeks if not more depending on the type of company and contracts they get.

What tips do you have for getting great cnc work done? Please leave your thoughts below!

photo credits: photos 1 and 6, photo 2 is Dropbox logo, photo 3, photo 4, photo 5 is GL Model logo (my fav cnc vendors).