Whether to Buy a 5-Axis CNC for Windows and Stairs
Is the versatility of 5-axis equipment worth the extra cost? June 29, 2009
Question
At the moment I am torn between an SCM 5 axis CNC machine and an SCM 3.5 axis CNC machine for solid wood machining of windows and stairs. I can only see that I would ever need a 3.5 axis machine as I do not feel there is a need for curved handrail 5-axis machining. Let’s face it, the only real use for a 5 axis machine in the wood working industry is for curved handrail and flaired stairs which I never get asked for. The dilemma I face is that if I go for the 3.5 axis I will never know if a 5-axis would of brought me more profitable work that I cannot do with the former. There is not really that much difference in price between an SCM 5 axis and 3.5 axis, although it is still about 25K sterling difference. Can anyone help me in my choice of machines?
Forum Responses
(CNC Forum)
From contributor J:
I am also curious what experienced users think about this as I don’t own a CNC yet. When I talked to other shops using CNC for doors and windows more than one owner said they would go 5 axes if they could do it over. They reasons they gave were the chance of inaccuracy when using aggregates for drilling and mortising, the fact the aggregates wear out at some point, more room in the tool holder and if you’re buying more than three or four aggregate that is almost enough for the upgrade anyway.
From contributor B:
We have been running a 4-axis CNC with aggregates to manufacture stile and rail doors for five years now. We acquired a 5-axis Routech (SCMI) five months ago. The difference in performance is astounding. Aggregates are limited to an RPM range that router bits perform poorly in, they introduce an additional element of inaccuracy in that they are not as ridged in the c-axis plane, and they are expensive, fragile and costly to maintain. We still run our 4-axis machine, but the 5-axis is used when precision and complexity is required. The increased productivity and quality of parts was worth the cost of the machine. Downstream assembly and finish time has been greatly reduced.
From contributor A:
If I had a choice I would definitely choose a 5-axis for what you are doing. I would however choose a 5-axis with a very large tool changer and drill bank on the side. I program a 5-axis for stair railing and it only has a 12 position changer. I already have nearly 30 regular tools mostly profiled so that's something I would definitely upgrade to. There are a few used SCM Chronos 5-axis for sale right now in the US. Make sure your machine is equipped with 5-axis tool compensation and invest in a good CAD/CAM software program.
From the original questioner:
Things like inaccuracies of aggregates and speed limitations are something I would have never known about and the sales people would of never admitted to me. I was also concerned about the size of the tool changer I would need. The Prisma 5 axis machine comes with a 24 position tool changer and for an extra 8K I could have an extra 24 position tool changer to make 48 positions in total, which I will probably have.
From contributor T:
I have been using CNCs since 1995 and have done many very intricate projects including solid wood compound curve entry door parts, custom molding, spiral stair case parts, carvings, etc. and I can tell you from personal experience that the vast majority of the people who think they need a 5 axis or have a 5 axis application are wrong. With only a few exceptions, you can do most anything you need on a 3 or 4 axis machine. Aside from the cost difference, 3 and 4 axis programming is much easier, and 3 axis machines tend to be much more rigid. In high end machining, rigidity is everything. Most people have just never had anyone who can teach them how to machine these intricate parts. You show them to your typical salesman (trunk slammer) had he says 5 axis cause he really doesn’t know any better and besides, it’s a more expensive machine so his commission is higher.
