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OK, so another noobie question. What controls the speed in which cuts are made? Looking at machines and wondering what to look for speed wise. I understand cheap models will be much slower, but looking at 5-6 machines. is there a cutting ratio, as in ___" per minute i should be looking at, max speed rates, router itself, etc. again just need a little more info to make a decision
thanks and everyone stay safe out there.
I can only speak to Vectric software but I can't imagine it being any different with any other company. When you create the toolpath's you tell it the speeds you wish to use. Obviously that is sometimes determined by the cutting tool being used and other times it will be the limits of the machine. Because CAMaster uses WinCNC as it's post processor it has a place where you and adjust the speed. It's a slider button. You can go to as high as 200% and I am unsure if the bottom is 0% or not. Never went all the way down before. Hope that gives you a better understanding. I'm sure that someone else can say it better than I did.
If you are asking what parameters determine the upper limits of axial travel speeds while cutting, it depends primarily on the stoutness of the machine, the spindle power, the axial motors and the tool size. On my 9 year old Stinger the x and y limits are factory set at 300 inches/min. and that seems to be reasonable considering the overall build- I rarely run that fast. Big industrial machines might cut 3/4" panels at 2 to three times that speed. The actual speeds for a specific job depend on a lot of factors including experience. Optimal speeds based on chip load may be beyond the capacity of many small machines.
Kevin is on the money if you are speaking to what factors pertain to how fast you can run. Its simply a combination of machine rigidity/robustness and spindle horsepower. Only you can decide how fast you need to go coupled with your work holding. How fast you need/want to run and how well you can hold the part, are pretty much the two deciders in my world other than budget. If your not going to be using vacuum holding, then that money can be pushed into machine/spindle HP. If your going to use through table vac, that will likely limit how hard you can push.
Its not really a simple formula but it is somewhat easy in that its just based on needs, work holding, and budget.
There are the speeds a machine can realistically achieve and the speeds that you choose to get the best cut and chip-load. The latter cannot exceed the former, but may be dramatically slower, depending on what you are doing tool-path wise, what material you are cutting, what workholding method(s) you are using, what tooling you are using and whether or not you have a spindle or a router motor doing the work. Machine stiffness comes into play, too...max speed isn't necessarily the best speed if it causes your machine to flex.
Buy the best, stiffest machine you can afford. And don't worry so much about top speed unless you're a production shop trying to push out gazillions of something.
Thanks everyone for the responses. I have been building furniture, cabinets, etc. for 30 years as a hobby. going to be looking to buying hobby cnc to start and see where it goes. always like to learn new things. CNC programming blows my mind though, but wth. Looking at shapeko xxl, openbuilds 1010, bobs e4. just trying to get a grasp what i'm doing. Love looking at everyone's builds andQuote:
Originally Posted by Jim Becker
just reading from the forum. kind of been in the background looking in. again thanks and maybe i'll come out of my shell and start more posting of questions and answering anything i can.
how would you rate for hobby.
1. openbuilds 1010
2. shapeke xxl
3. bobs E4.
will not be doing anything extra large, thanks again
I'm at the same phase as you. With so many choices it can be daunting to figure out which is best. The Shapeoko seams to be the standard but it's design is a little dated. They do have lots of people with them so beyond their support (which seams top notch) there's plenty of users to also help. The other two I haven't looked too closely at. I would want to know what material the E4 is made from. The Openbuilds seams like the standard aluminum extrusion style. It looks like a nice tool but I assume it's a kit that will require time to put together. Building it does give you the chance to learn how the machine works.
All three of the machines you listed use wheels riding on a track. That seems like a potential weak spot to me. Any problems or wear will impact how accurate the axis is. Some people don't like belts and I think using them like Shapeoko does is going away but they are easy to replace. The other options are rack and pinion, lead screws, or ball screws. Each has it's own pluses and minuses. My preference would be ball screws.
I'm only getting started, but what Alex notes about plus and minuses certainly is a consideration. For just that reason - that wheels and a belt require constant maintenance, I elected for one of the new kids on the block, OneFinity, which is a ball screw system. Here's a link, and I'd recommend you check them out: https://www.onefinitycnc.com/
While the wait time is pretty long and there's not much information from people who now have one since it's still pretty new the "Woodworker" is at the top of my list right now. Almost everything I repair and calibrate at work has liner slide and ball screws. This is stuff that has to repeatedly move to less than .1mm. Often they do this 10s of thousands of times before any sort of work. I would like to know how hard it is to convert the OneFinity to a closed loop system. Even if it was just feeding back to the driver. Also I would like a system that has real home switches. I think the 1F just moves until it reaches the limit of it's range. I assume anything I buy in the $2k range is going to cost me up to another $2k as I upgrade it.Quote:
Originally Posted by John Nordyke
I assume you mean stepper motors with a cog belt driving the feeds on X and Y axis's. Z is usually a ball screw and direct drive from the motor. There is so much more to a good CNC than the drive type. There is not a lot of maintenance required of the drive system. Timing belts are strong and reliable. Where do you get that they require constant maintenance from? Maybe on low end machines but certainly not on the better ones. Just wanted to clarify that the drive system shouldn't be an issue for most. It also depends on what you hope to do with it. Good luck as you start down the CNC rabbit hole.Quote:
Originally Posted by John Nordyke
A major consideration for me would be the ability to use a spindle instead of a router. I you intend to do a 3D carving in a basement shop, your family will get to hear the router screaming for 6-8 hours solid. With a spindle you can stand next to the machine and talk. Your software will have something to do with the cutting speed as well. Complicated files need a look ahead to use higher speeds. Most little machines don't have the rigidity to travel 20" at a high cutting speed and then make some sharp direction changes without getting a shake in the machine. Material and material thickness will have more to do with cutting speeds than marketing numbers. And with the term "speed" there is cutting speed, travel speed, and plunge speed
Thanks all to question, all makes sense, just getting into the creating in software, a little overwhelming, but im sure a year from now, i'll be much better
I misspoke and said stepper motors when it should have been servo motors.Quote:
Originally Posted by Ronald Blue
Richard there are many CNC's running routers instead of spindles. If you have to save dollars you can add a spindle anytime. You can't bolt more rigidity on in 5 minutes and probably not ever but a spindle can certainly be added. I eventually will add a spindle as my main spindle but I don't ever see a need or benefit of upgrading the two additional smaller routers.. Maybe after retirement if my usage dictates it but I'm in no hurry at this time. It's not a basement shop so that's not a concern. There are many options out there. Choose wisely.Quote:
Originally Posted by Richard Coers
You are correct the small belts used on those units are a constant source of problems. They all seem have have built in tensionors but even at that they usually need manual tweaking before they do an important job. The first major upgrade is going to screw drive!Quote:
Originally Posted by John Nordyke
I am not aware of any large CNC router running drive belts for the X or Y axis its either screw or rack and pinion.
My Hitachi router ran for over 8 hours on a job without an issue, and its rated the quietest on the market. I ran a 3 phase VFD driven spindle on my 4x4 machine but went back the this router on my small WorkBee.