Hi,
I’m new to CNC and the Onefinity. I’ve done some reading here and elsewhere online about feeds and speeds and getting myself up to speed. I’m wondering how hard i can push the Onefinity and what it may be able to handle. I will be using it primarily to cut guitar bodies (basswood, alder, mahogany…etc).
Just for an example…Say i’m using a 1/4’’ 2 flute bit, makita router set on 2 or 2 1/2 (12000, 14000 rpm). Per the calculations, assuming i’m shooting for a .009-.011 chip load (which is somwhere around what i’ve seen for recommended chip load) that puts me somewhere between 216-308 ipm for feed rate, depth of cut at .25 per pass (1x bit diameter) and plunge rate around 100-150.
Assuming my calculations are correct and the target chipload is correct, this seem aggressive.
Before running at test (and potentially breaking something) I’m wondering if the Onefinity will be able to handle this or if i should consider backing off. I was thinking to start scaling this back and if all goes well incrementally push it a little harder. Ex…maybe start with 100 ipm feedrate, somewhere between 25-50 for plunge rate, .125 doc (1/2 bit diameter) and keeping the router somewhere between 12000 and 14000 rpm.
Anyway, I’m not going to be doing mass production or anything so i’m okay if i need to run things on the slower side, but just wondering from those that have experience with the Onefinity what i can realistically expect.
In general, I think you will find that the OF is not the limiting factor. The ball screws, the couplings to the stepper motors, and the stepper motors themselves are the only components of the OF itself that are subject to the forces generated by feeds and speeds. None of those are going to fail before you either 1) snap a bit, 2) bog down the spindle/router or 3) have a hold-down failure on your wasteboard.
One of the reasons so many go for a third party spindle upgrade over the Makita is because router speeds make it very difficult to hit those theoretical chip loads. The Makita running at 12000 - 14000 RPM will bog down before you get to optimal chip load - you don’t get full torque except at higher speeds with a router. A true CNC spindle is still “torquee” at slower speeds.
I’ve been running mostly at the rates mentioned above in the original post, i haven’t tried to push too much harder. If anything i think the Makita may be the limiting factor and not the machine itself. I may get a 15.5kw spindle and go from there.
You will find that most all formulas for speeds and feeds and chip loading don’t take machine HP or torque into consideration. The OF is designed well and is more than strong enough. The limiting factors are the torque of the steppers and your spindle. So for larger cutters you’ll never be able to get the recommended chip load. If your feed rate is too high you’ll stall the stepper and lose steps. With the open-loop control that means you’ll also lose position. Slowing your feed rate down means you have to slow your spindle to keep the same chip load. For standard routers (brushed motors) when you lower the RPM you decrease HP and torque. That means that RPM will decrease even more, chip load will go up and eventually you’ll break your bit or stall your stepper. True spindle motors (VFD driven induction motors) pretty much maintain their torque at lower speeds. The do usually have a recommended minimum speed (10,000 RPM?).
So, where does that leave you? Generally you’ll have to stick to smaller bits (1/4" or less) and go a little slower. You’ll also have to stay on the smaller side of the recommended chip load. You don’t want dust for chips unless you’re doing a finish pass on some 3D carving with a ball endmill. If you’re getting dust you’re on your way to burning up the cutter. Unfortunately there’s no magic numbers that anyone can tell you. The formulas work well for large industrial machines but not so much for these small guys. It’s going to take some time for you to learn what your machine can do in each material. If you ask very specific questions like - What speed and feed should I use for a 1/8" cutter in oak? - someone in this forum can tell you what worked for them.
The OF is awesome but at the end of the day it is a table top machine. There are some things to help like a torsion box or other reinforced table and a spindle. It meets my expectations.
Are you still running those numbers, or did something different work for you? I am doing the same thing as you, cutting guitars, basswood and cherry, and looking for some good numbers. Was the Makita able to handle above the 300 IPM at 18K RPM?
I found that the factory settings of the onefinity left marks on my carves. I went through all setting and lowered max speed and jerk by maybe 30%
I have a much slower machine now that is much more precise. I don’t really care about speed, I am interested in precisely sculptured 3D objects. The marks when the 1F was cornering are gone.
I made a folder where I backed up different speeds and settings.