Speeds, Feeds, and Strategies for Bench Top Mills

[CL_MotoTech]

The wax prototype fit, we actually sectioned it on the band saw so we could inspect internal clearances. Pretty cool.





Facing got a little dicy, but it worked out. Overall pretty happy with the results. The model was the weakest link here. I could have cleaned it up a little bit.

Anyways, the mill has been working quite well, but I decided to buy some Teknic servos to run direct drive on XY. I found a good deal on them used so I figured I'd give it a shot. I'm not sure what I am hoping to gain, perhaps just a little peace of mind?

[steelcogs]

I have clearpath servos on all 3 axes. I bought my mill and they were already on it. I did the math of the mill + the components and it turned out to be a pretty good deal largely because of the price of the clearpaths lol.

I've only ever messed with stepper motors that are on the small CNC router/3D printer scale so I've never had to deal with the stepper drivers or anything but I like the clearpaths. No drivers, just a power supply and I believe they get wired very similarly to the motion controller like a stepper would. I like that there is an autotune feature for them on their software, no missed steps, etc. If they stall out you can wire them to an estop/motion controller so if you have a program that for whatever reason would cause them to run to the end of their travel, instead of the machine flipping out it'd just stop everything altogether. Maybe steppers have something similar to this?

All in all, they're pretty neat. I'm hoping the large NEMA34 I have on my Z can handle the 50+lbs I just added to the head with my new motor without needing a counterweight lol.

[CL_MotoTech]

I wrote a big old response and hit post but it apparently didn't go through.

In summary, the clearpaths are super expensive compared to steppers and drivers. Luckily I got them more than 50% off. Hopefully they fix up the very intermittent and unpredictable issues I have with my X axis stalling. 300ipm or whatever rapids sound pretty wild too.

[yelims20]

Yes, Clearpath servos are a bit salty... I bought 3 for my G0704 plus the 75 volt power supply and cables (totaling more than the G0704). But they work better than steppers, just like ballscrews are better than leadscrews. Has anyone looked into Clearpath as a spindle motor? I'm thinking not having to use a VFD would be a plus. They have a series of servos that have a mode which can be rpm controlled with the standard 0-10v. Costly, I'm sure.

[CL_MotoTech]

These two looks roughly close to my 2.2kw BLD with VFD in wattage. After import and wire transfer fees I was in about $800 for my Adlee setup. For the Clearpath you'd still need a power supply. Ouch. And my BLDC tops out at 6k, whereas the Clearpath does less than half that. There could be better options from Teknic...

https://www.teknic.com/model-info/CP...tage=230VAC3ph

https://www.teknic.com/model-info/CP...tage=230VAC3ph

That makes me feel pretty good about my motor choice. I think mine has better constant duty performance too.

I got the used servos in the mail, they have some minor scratches and small marks on the housing, but otherwise look really clean. Assuming they work, I think I got a good deal. I am just waiting on the IPC 5 and cables now. I might as well start looking for a used Nema 34 for the Z, I'll already have the power supply to run it. The handwriting is on the wall.

[CS900]

a bit off topic, but how do you like that shars vice?

[CL_MotoTech]

Love them, I own three. Two 4" vises that are a very nice fit for the G0704 and the 6" in the picture above which works great in the orientation seen.

I measured all three of them on my surface plate when I received them and they all came in under the specified variance. For the type of work I do, sort of high end hobby use, I honestly don't believe there is any better value given the quality.

These vises were an incredible jump in performance over the Grizzly vise that came with the mill. That vise spit parts out all the time.

[CL_MotoTech]

The pump cover works. We had a fairly successful test yesterday.

[yelims20]

Cool car! That reminds me of the big slot cars of the 1960's. I bet that's a blast to drive

[CL_MotoTech]

It's modeled off of CanAm cars of the 60's and 70's. Being homebuilt meant they could only do so much. Underneath it's basically a Formula Ford of the era but with modifications to fit the wider monocoque. It's powered by a Suzuki GT750 two stroke, makes about 120hp. It weighs 900lbs.

It goes like stink despite being 45 years old. It's faster than most modern GT cars everywhere but the end of the straightaway. A Porsche GT2 RS owner was pretty annoyed that he couldn't catch me and I was peddling it, not even pushing as we were doing basic shake down runs for reliability not pace. A GT2 RS is a $300k car and has a top speed of 200mph plus, whereas our car is good for about 135mph lol. Around a road course average speed is king, and it takes quite a bit of car to rival something as light as our sports racer.

[yelims20]

It's cool to see the machining hobby support other areas of interest. Well played!

[CL_MotoTech]

Thanks! One definitely feeds into the other!

I was going through my tools getting ready for some minor work and notice my face mill might have been running a spot aggressive.

[yelims20]

you'll be putting that in the lathe... lol

[CL_MotoTech]

I hit it with my automatic center punch and the entire slab fell right off. I should have grabbed a photo.

I used the face mill to basically rough off the backside of the water pump cover. Obviously I didn't get the S&F's right. I faced the cover too, but with a much lighter cut, so somewhere in the roughing phase I am guessing is when the melty bit happened as the finished surface is pretty nice. Occasionally I turn the coolant off to get a look at what is happening, maybe I caused it then? Who knows?

[CS900]

I hit it with my automatic center punch and the entire slab fell right off. I should have grabbed a photo.

I used the face mill to basically rough off the backside of the water pump cover. Obviously I didn't get the S&F's right. I faced the cover too, but with a much lighter cut, so somewhere in the roughing phase I am guessing is when the melty bit happened as the finished surface is pretty nice. Occasionally I turn the coolant off to get a look at what is happening, maybe I caused it then? Who knows?

in my experience that generally happens when your ramp angle into the workpiece is too steep and the depth of cut is greater than the distance from the bottom of the insert to the bottom of the cutter body.

[CL_MotoTech]

That's likely what happened, I inadvertently got my soft jaws at one point. I was running it a bit heavy on step down on the roughing ops though. So maybe a combination of both? I'll never know because I don't plan on making one of these again.

[CMENDOZA]

the alloy also can play a part in build up like that, 3003 aluminum gums up a lot faster than 5052, not that your piece was 3003, but i have run into variances in the alloy before(not typical), just got done reading your thread, i run multicam machines and they all have technic servos, quite costly but waaaaay better than stepper in my opinion.

[CL_MotoTech]

This was 6061. A material I’m pretty familiar with.

On one of the pages I posted some of the shocks I work on. They are made of some super gummy aluminum. It took me a long time to get my F&S set to get nice results with them. Especially so with the slot cutter. Lots of coolant and nice slow seems to be the recipe. Once it starts to stir it’s all over.

[Teknic_Servo]

Hi yelims20 and CL_MotorTech,

I'm an Applications Engineer at Teknic and I saw your posts. I was hoping to clear up a couple points and perhaps answer your question.

We are often asked if a ClearPath motor can be used as a spindle drive/motor. The answer is: Yes. In general, ClearPath motors will work very well in spindle applications if the motor is sized properly – in terms of both torque and speed. In fact, when choosing a motor for any application, two of the most important details are the required torque and speed (the product of which is the motor’s power rating). It is also important to understand that two different motors can have the same power rating but have very different torque and speed ratings (this has to do with the motor’s winding configuration).

ClearPath could be a very good spindle option for many benchtop mills depending on the speed requirement, feedrate, and type of material being cut. However, for higher speed spindle applications like industrial routers (think 10000+ RPM), you’d need a motor designed for those speeds; in this case ClearPath would not be a viable option.

If you have an idea of the torque and speed needed for your spindle, you can use our motor selection guide to pick the best option:
https://www.teknic.com/products/clea...lection-guide/

When it comes to controls, like yelims20 said, if you want to use ClearPath with standard 0-10V analog velocity control, a ClearPath-MCVC combined with an Analog Send Unit (PN: ASU-FR510) would be a good solution. The ASU converts 0-10V (or 4-20mA) analog signals to digital frequency signals compatible with ClearPath. Alternatively, ClearPath natively supports digital PWM or quadrature signals for speed control as well.

If you plan on doing drill and tap operations, or any other operation where positioning and coordination is important, ClearPath-SD (with step & direction input from the controller) would be a great choice. ClearPath's torque availability at zero/low speed can be especially advantageous in this case.

Since CL_MotoTech mentioned power supplies too, I thought I'd add that the two servos he referenced (https://www.teknic.com/model-info/CP...tage=230VAC3ph and https://www.teknic.com/model-info/CP...tage=230VAC3ph) are AC input servos and would not require a separate power supply. However, the smaller DC input ClearPath servos (NEMA 23 and 34 sizes) do require a separate supply.

I hope this is helpful. If you have any other questions about ClearPath, please feel free to reach out to us directly using our Contact Us form (https://www.teknic.com/contact/) or by phone (585-784-7454).

Best regards,
Matt C. -Teknic Servo Systems Engineer

[yelims20]

thank you, Matt