Making Small Parts with a CNC Router
A CNC beginner gets advice on various ways to hold the work in place. August 8, 2005
Question
We're getting ready to purchase a router and I am interested in techniques for cutting small parts such as hard wood radius trims, etc. on a CNC router that is also used for nesting frameless cabinet parts. Does anyone have any advice on vacuum strength/volume or fixtures/pods/pop up pins, etc?
Forum Responses
(CNC Forum)
From contributor T:
One approach would be to manually nest as many as you can get in your built up stock material. Then, cut along both sides of the parts, but do not cut them loose. If they are very thin, once you cut them loose, they will take off on you. You can then remove them from the CNC and manually cut them loose.
From contributor S:
Work-holding of small pieces can be a major headache. We frequently rout a tabbed tool path, and all the components in the nest are connected to the scrap by small tabs which are routed away using a hand router with a bearing guided trim bit.
For rougher work, they can simply be pressed out and sanded. For MDF components where we are going to edge sand anyway, the profile is routed to a 2 mm thickness. Then the piece is flipped over and the components routed-out in the same way - a profile, drum, bobbin, or oscillating sander, then removal of the witness marks.
From contributor E:
We cut small parts almost exclusively and have developed our own vacuum and jig system. It is fairly simple, but relies on needing fair cut quantities of the same parts to make it viable. We cut 70 mm diameter circles with a 22 mm hole in the center 22mm thick, and routed the profile all around 30 at a time without having to do any further finishing after the CNC.
From contributor M:
I would recommend taking a look at Busellato. Their machines can do everything you ask. The machines all have fixture capability. Spoil boards can be used as well. They also have a huge variety of clamping and hold down devices. Setups are completed easily, and the software is very user friendly.
From contributor K:
I have a couple of suggestions for you if you are interested about cutting small parts on the CNC. If you can use more than one head at the time, you will be cutting the time. Also, for cutting small parts on the machine, use tabs of a thickness 1/6", and at the end of the program you go back and cut them again or they will fly. You can also leave a 1/3" for all depths and cut it by hand.
From contributor M:
To the original questioner: I feel the need to elaborate a little more. While the other guys are talking about leaving tabs and onion skins, they have also created the need for a secondary operation (edges need to be trimmed and/or sanded). The options I spoke of will give you a finished piece when you take it off the machine.
In addition to that, the Busellato's can also do pendulum processing, so that while you are loading/unloading one side of the machine you are creating more parts on the other side of it.
Ultimately you have to decide what is best for your business, but based on my experience as an end user/programmer, I know the Busellato's can do all that you have stated a need for.
From contributor J:
To the original questioner: Why spend money for a CNC Machining Center and then finish the parts by hand? There is no need to program tabs or worry about the depth of cut when considering onion skin cutting. Both require secondary processing, and that is time and time is money.
The toughest parts I've seen cut using the SBC were Napkin Rings from 5/8" Baltic Birch. The operator cut almost 900 finished parts from a 48" x 96" sheet and did not loose a single part.
