Best Mini Mill for Rotary engraving

[nosplinters]

Howdy,

Now that I've gotten some good feedback on some Bench top mills, I have some other questions pertaining to rotary engraving.

Has anyone had good success with their mill and if so, what mill do you have?

I'm looking to rotary engrave on to items such as SS flasks, pens, pendants and knives. Most rotary machines that I've seen are spinning at around 10K-12K RPM. With that said, I have only seen two Mills on the market that have such speed capabilities for engraving (Sherline and CNCMasters).

The other questions would be is it possible to stop the Mill from spinning in order to do diamond drag? Is there software that can deal with curved items (such as a proximity sensor)?

Last question...what software will allow for rotary engraving of images in 3D, Font filling, etc.?

Sorry for all the questions...I want to make sure I make the right choice for machines.

Thanks
-Ed

[project5k]

what i think that you are going to find, is rather than going the proximity sensor route, you will be better off measuring the item, drawing that up in the cad software, and then applying the design to that.. when you start talking about autosensing shapes and coutours your getting way way deeper than most are willing to go.. there will be extensive software, hardware, and electronics involved...

as for high rpm units, you could go with something like an x3, and then add a high speed spindle off the side of the main.. something like an air powered one, or some others, depending on what you can make work.. heck you could even hang a laminate trimmer off the side of it, and thoes babys can really get up there in the rpms.. and i've seen pictures of it done here on cnc zone...

as for stopping the spindle, yes, mach 3 can handle that.. you could set it up to control either the main, or the auxiliary spindle through a breakout board and relay(s) though i dont think that i would reccomend dragging anything if your then gonna turn the spindle back on at 10k+rpm's

and dont forget that your gonna need a 4th axis, driver, and some way to hold the part your engraving... like a lathe chuck of something of that sort...

[Stepper Monkey]

I would differ with a couple of the points made above. First and most important, as one who owns and has owned five different brands of tabletop mill including an X3, and one who does much rotary engraving, an X3 is the LAST machine I would recommend for engraving. Flat out, no buts. It is a good machine, but not for this. That is much akin to saying to start out with a Caterpillar tractor chassis to build a racecar from.
Rotary engraving requires a very light and accurate touch.
You are looking for a scalpel, not a meat cleaver. I wouldn't doubt that after much fiddling you could probably get an X3 to do engraving at least somewhat adequately, it is certainly not the right tool for the job. Even if you did such, it is way more expensive and cumbersome of an option.
Often, people on here simply default to the bigger hammer approach and forget that there is more than one kind of job, and there is more than size of hammer sold at the hardware store for good reason.

Secondly, I would agree with the idea of skipping the autosensing unless you are willing to buy some already built and seriously expensive industrial gear that has it built in. I have wanted an autosensing option forever but it is just not yet feasable on our scale.
I would say unequivically that manually programming in the curvature does not work at all by itself. The tolerances on engraving are too tight, any misalignment, tilt, or radius errors of even .001-.002 become very, very noticeable with a rigidly mounted rotary bit due to the nature of the engraving bits shape. Trust me, you will NEVER get it perfect, and even if you did the radius on something like a flask is inconsistent enough across its face it wouldn't matter anyway! This is a problem that plagues us constantly, and there is no good way around it currently other than a springloaded "floating" bit holder. There have been a couple of discussions on building these on the engraving forum. Matched with manual mapping it solves most of the common problems most of the time - very cheaply and easily too - but is still no magic bullet!


I have had my best success on very smooth, lightweight slides with tight thread pitches. My favorite Z axis has a four-ounce, 40,000 rpm ceramic bearing dental handpiece on a very lightweight skeletonized bracket. It is designed to take 1/8" engraving bits only. It is 0.9 degree per step Nema 17 driven to reduce rotary inertia and vibration issues. Reduction of weight on the Z is important. This is one reason bolting something to the side of an already 70 pound headstock on an X3 is rather pointless. Smoothness is key when rotating a .005 tip (or less) vee bit through metal at 30,000 rpm. Real easy to break.

If you don't want a dedicated machine like a Roland or Model Master, or a permanantly modified homebrew like me, you can still do quite well with a Taig if you remove the Taigs original motor and spindle, and replace it with a bracket and spindle something like Wolfgang Engineering sells on Ebay. This is easy to switch back and forth with the original headstock as the assemblies mount with a quick release dovetail. Same might go for other light machines like a Sherline but I haven't tried any of them. You need accuracy, resolution, and speed for engraving but no real need for high capacity. A machine with the ability to move 1" mills through steel and do fast rapids is not a requirement here, and actually hurts your cause quite a bit before you even start.

[nosplinters]

Great, thanks a lot guys!

A while back I had a rep come over to the shop and demo a Vision rotary machine. The cost was around $12K. I wasn't too impressed, especially considering the guy destroyed two of my flasks before he got it right.

Anyway, I'm looking for something that can mill out some parts for a project I'm working on as well as allow me to do some engraving. I really like the Sherline, but it seems to be a bit spendy for what you get. I imagine it would do engraving well with the pneumatic attachment; however, I'm sceptical about the aluminum mill work. I really like the SmithyCNC 516. Seems like a pretty nice machine; though I'm not sure how it would be to retro fit it for a high speed rotary attachment.

Stepper Monkey: What software do you use for your engraving work? Do you have any pics of some engraving work you've done?

Oh, what would the 4th axis be used for anyway? I imagine I'll need this to do some wheels and gear work.

Thanks!
-Ed

[project5k]

Stepper monkey, you make some good points. i hadnt considered the mass of the x3 vs the job... where 99% of my work will be heavy hogging and pocketing, and 1% engraving, i think that i can come out with good enough results for what i need, but for what nospinters is talking about i definately like your suggestions for equip config over my original suggestions...

[nosplinters]

Ok, I've now spent the last couple hours crawling around on the net. It's looking like the Taig is the winner (for what I need). I did find that the machine can come with servos rather than steppers; however, I'm wondering if I should get the thing CNC Ready and add my own servos and controller.

Anyone know what a good set of servos and controller would be? I'll need USB, considering I don't even have a parallel port on this computer. I'll also need a 4th Axis port. I found a couple (FlashCut and camPOD). FlashCut is very spendy and camPOD is only a conversion box, which is also spendy.

It seems like Mach3 softare is the way to go; therefore, I'll have to make sure whatever controller will support Mach3 as well.

Oh, here's the best thing I came across - Spring loaded engraving tool. WOOHOO! http://www.2linc.com/products.htm

Thanks
-Ed

[Stepper Monkey]

Originally Posted by nosplinters Great, thanks a lot guys! A while back I had a rep come over to the shop and demo a Vision rotary machine. The cost was around $12K. I wasn't too impressed, especially considering the guy destroyed two of my flasks before he got it right. Anyway, I'm looking for something that can mill out some parts for a project I'm working on as well as allow me to do some engraving. I really like the Sherline, but it seems to be a bit spendy for what you get. I imagine it would do engraving well with the pneumatic attachment; however, I'm sceptical about the aluminum mill work. I really like the SmithyCNC 516. Seems like a pretty nice machine; though I'm not sure how it would be to retro fit it for a high speed rotary attachment. Stepper Monkey: What software do you use for your engraving work? Do you have any pics of some engraving work you've done? Oh, what would the 4th axis be used for anyway? I imagine I'll need this to do some wheels and gear work. Thanks! -Ed

I would imagine the Sherline might be fine for engraving but the aluminum work is right out. It is a bit spendy and a Taig will do much bigger and tougher work for similar or less cost. The Smithy looks even better still for not much more at all - I will have to look at one up close but it looks like a machine done right, and at a great price for the features on it. Fitting it for high speed may or may not be troublesome though, I see your concern.

I use Artcam for engraving, it makes it easy and fast. Really powerful and intuitive to use. Might not be the answer for you, though, as it is really a comprehensive 3D relief modeling program that was meant to do far more than just engraving, and so at 10 grand it isn't worth buying just to use it as an engraving program!
I used to just use Corel to lay out any work as vector files and then convert them to g-code. This is an incredibly easy and powerful way to do 2 1/2 D engraving very cheaply, as with the ability to use almost any standard font and to use the "trace" function to convert images to vectors the sky is pretty much the limit unless you want to move into full 3D relief modeling.

As for the rotary axis, it comes in very handy doing rings and pens and the like. Anything cylindrical. I even did a complex portrait entirely around a revolver cylinder. I'll see if I saved a picture of it. Makes gun engraving a snap.
For sourcing them, the basic Sherline rotary table is way more than adequate, and if you look close most manufacturers of even the $20k machines just use it instead of trying to make thier own. They are really just that good. It is the one real hands-down winner of a product in the Sherline catalog.

[Harryman]

I use CoolMuscle servo motors on my desktop mill and WinCNC to drive them. The motors aren't cheap but are fast and incredibly smooth. I used to use Flashcut with steppers, but WinCNC is much faster, it "looks ahead" farther, and you can configure it for any motor. Flashcut wanted big bucks to upgrade my stepper version to servo so I just sold it and switched.

I doubt speed is a big issue with engraving, but milling my parts now, they're done in a fifth the time it took with my old set up, and with better surface finish. I know a guy who just switched his mill from Flashcut to WinCNC, no other changes, and it cut his time down almost by half.

I agree about the 4th axis, Sherline's is the best thing in their line, that's why its on a lot of other manufacturers mills.

[nosplinters]

Hey millingjeweler,

What type of Mill are you using? I totally agree with going the Servo route verses the Steppers. It definitely looks like going with a CNC Ready and adding the Servos and building a controller will be the best way. Considering I need USB and everyone tends to sell these at an very high price.

I have a budget around $3K-$4K. Hopefully, it's possible.

Thanks
-Ed

[Harryman]

I use a Minitech Pro. A little bigger and burlier than a Sherline or Taig. I'd take a Taig over a Sherline any day though.

Keep an eye out in ebay if you're not in a hurry, I see Minitech, Model Master and similar chassis with or without slides, motors etc, from time to time.

[Stepper Monkey]

I would actually suggest spending the money on a parallel card, they are less than 10 bucks and have numerous advantages. USB can be very problematic for a number of reasons, I won't go into them here as they get pretty technical but my advice is simply to steer clear. There are ways to use it, don't get me wrong, but they are pretty clunky workarounds. No simple, reliable, and cost-effective method is really possible right now. If you absolutely cannot use parallel, RJ45/CAT5 is possible over a network card.

As an owner of Flashcut gear, I can say I am very disappointed in its performance for a number of reasons. Other than convenience and easy setup, and possibly long-term reliability, it fails to outperform any other solutions I have seen while actually cutting, even the cheapest. I concur with Millingjeweler that most other systems are a lot faster and smoother, even if harder to initially setup.

Mach is a real winner, definitely stick with that.

A separate fourth axis "port" is not required. A simple four-axis setup using Geckos will work fine with Mach and a parallel. Only if you already have a three axis setup, and need to add a fourth, is buying anything special needed - and then simply buying an additional single-axis driver from Gecko is sufficient regardless of the brand of your original setup. If you do servos that is the way to go. I personally don't believe that below a certain size and load range there is any real advantage to servos, so I use steppers for smaller, lighter duty units as they are WAY more cost-effective and simpler than servos. I do like servos, there are places for them where nothing else will do the job properly, but I don't see much advantage for them in your size requirements. There are many very good, experienced opinions that differ with mine on that one though! Use whatever you feel comfortable with.

The engraving tool looks awesome, it is exactly what I meant. I highly recommend them, I don't see how anyone can survive without them actually. I built my own for about 15 bucks before I knew the 2linc unit even existed, so I can't speak for it firsthand but it looks lika a really good solution.

[project5k]

i'm glad someone brought up the lpt card, i was thinking about commenting on that as a much easier and cheaper way to go over the usb conversion, then as i read on i found that it was already suggested.. much less headaches, cheaper, simpler, and just all around a much bigger bang for the buck..