3018 Spindle Upgrade

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3018 cnc spindle upgrade

There are a few 3018 cnc aftermarket upgrades available such as a Laser Module, but the least costly and most simple upgrade is the spindle motor.

Sainsmart sells their Genmitsu GS-775MR 24V 20,000 RPM spindle + Collet Holder + Motor Noise Suppression, for 3018 Series.

This is the motor I will be reviewing and testing in this article. This motor upgrade provides double the rpm over the stock motor going all the way up to 20,000 rpm. 

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Why should you invest in a 3018 cnc upgrade kit?

The 3018 is a machine well known for its lack of rigidity and being able to run smaller tooling helps reduce the load on the machine.  (3018 cnc Pro review)

But to run smaller end mills you need more RPM and this is what this upgrade gives you.. 

The 3018 spindle speed with the standard motor is 10,000 RPM so this upgrade gives you double the RPM.

This extra speed can really help for small ball end tools. It will be much easier to achieve a smooth surface finish while still running at a reasonable feedrate.

Sale
Genmitsu GS-775MR 24V 20,000 RPM Spindle*
  • DC: 24V. Speed: 20000/min.
  • Experience a quick and easy upgrade for your Genmitsu Desktop CNC.
  • Pre-installed motor noise suppression PCB provides enhanced performance.
  • It's compatible with All 3018 Series CNC router. Applied to lathes, mills, car hoists, pumps & conveyors, etc.
  • Double ball bearing brush. CW/CCW rotation.

There is also a 3018 cnc machine available with this spindle included in the price, with the added advantage of coming with the upgraded power supply. (more on this power supply later)

Genmitsu 3018-PRO CNC router kit*
Genmitsu 3018-PRO CNC router kit; 1pcs CNC Spindle Motor with ER11 Collet. (Note: They will be shipped separately)
Premium Power Adapter: The 3018-PRO has brought safety improvements to the adapter, with CE/FCC/UL-approved. Strong built for heavy-duty and long usage performance, making input/output stably even when work for a long time or work with a laser module.

Genmitsu GS-775MR Advantages?

Being a direct replacement from the manufacturer, this motor is exactly the same size as the standard motor and it could not be easier to replace. 

Just loosen the bolt on the 3018 spindle mount, lever it apart with a screwdriver, slide out the old motor and slide the new one in, it’s that easy. 

The wire connections are clearly labeled, just push the spade connectors back on. 

This motor is a low cost, plug ‘n’ play option.

Genmitsu GS-775MR Disadvantages?

The main disadvantage with this motor is the extra power draw. 

Spinning this motor immediately up to 20,000 rpm on start up is going to overload the standard power supply and your machine will shut down.

The answer to this issue is to buy the upgraded power supply to go with this motor, the problem being the power supply is nearly twice the price as the motor itself.

There is another solution to this problem and that is to not start the motor at full rpm, but to increase it gradually. 

Sainsmart mentions this workaround on their website, even giving you an (overly long) G Code solution to add into your programs.

I will test this solution later in this article and demonstrate the (shorter) G Code needed to prevent overloading your power supply.

Unboxing the Genmitsu GS-775MR Motor

The motor comes with an ER11 collet holder and a ⅛” ER 11 collet. The collet holder is already attached to the spindle and in my example it was not set as far up the spindle as I would have liked. 

Genmitsu GS-775MR

I was going to loosen the set screws and move it further up the shaft, but on closer inspection I could see that it was glued with loctite on to the shaft. I spotted a solid red blob of glue at the top of the collet adapter. So I just left it alone and continued with the testing.

glued on er collet holder
You can see the red Loctite around the shaft

Installing The Genmitsu GS-775MR

As mentioned previously installing this motor was a breeze, just twist a flat head screwdriver in the slot of the mount to lever it apart. Slide out the old motor and slide in the new one.

Genmitsu GS-775MR

Testing the spindle

After spotting the red loctite on the shaft I decided to check if there was any run out on the spindle with a dial test indicator. I placed the dial on the inside of the taper for the er collet.
First I checked my existing ‘standard’ spindle before I took it out and found it was running about .006” off center. This would explain some of the vibration from the machine when it’s running. (I used the slo-mo function on my phone)

YouTube video

The .006” runout on the original spindle was concerning, if the new GS-775MR motor was this bad the vibration would be even worse at 20,000 RPM. Fortunately the new spindle was a lot better with about .001” of run out.

YouTube video

The next test was to run the motor up to max RPM. 
Bearing in mind I was running the original power supply I wrote a quick program to ramp the 3018 spindle rpm up in 10% increments dwelling for a couple of seconds between speed increases.
This slower progressive increase in rpm will also let me observe how it runs throughout the full rpm range.

The program is shown below, (G04 = dwell, the P value is the dwell time in seconds)
(The firmware setup for this machine spindle is for S1000 = 100% so S1000 = 20,000 rpm.)
S100 (2000rpm)
M03
G04 P2
S200 (4000 rpm)
G04 P2
S300 (6000 rpm)
G04 P2
S400 (8000 rpm)
G04 P2
S500 (10,000 rpm)
G04 P2
S600 (12,000 rpm)
G04 P2
S700 (14,000 rpm)
G04 P2
S800 (16,000 rpm)
G04 P2
S900 (18,000 rpm)
G04 P2
S1000 (20,000 rpm)
G04 P2
S100 (back down to 2000 rpm)
G04 P2
M05
M30

Still running without the collet, collet nut and a tool, the spindle was quiet. The noise from the fan was just as noticeable as the whine of the motor.

YouTube video

Next I clamped an end mill in the spindle to check if the run out was worse than the inside taper of the ER collet holder. As expected it was worse, running about .005” out but I managed to improve it by wiggling the collet as I tightened it. 
I got it running within .002”, the accuracy of ER collets can be hit and miss.

YouTube video

I then re-ran the test program again to see the difference with the tool in the spindle.
This time it was noticeably louder and the machine resonated quite a lot at the mid range speeds but settled down again at higher RPM. 

YouTube video

The vibration at the mid RPM range was probably due to the minor slop in the leadscrew nut and bearings. This was an issue with the older motor also but the faster spindle speeds exacerbated the noise. 
One of the spindle mount bearings came loose and almost dropped out.
If you are running this spindle without the upgraded power supply you don’t have to use a program like the one above, it can be ramped up to max RPM quite quickly.
An example of the G Code you could add is below, this will ramp the spindle up to full rpm in 1 second.
S200 M03
G04 P.25
S400
G04 P.25
S600
G04 P.25
S800
G04 P.25
S1000
Adding this to a program looks a little clumsy because it replaces one simple line of code (S1000 M03). But it’s not a big deal to keep a copy of it in your programs folder and just copy & paste it in the beginning of your programs when needed. 

I recorded the machine running the code so you can see how quickly it gets to full RPM.

YouTube video

Conclusion

Is it worth the upgrade? 

For what it costs, yes, it’s definitely worth it just to get the extra RPM. It is exactly what you need for smaller end mills. 

Another possible advantage is an increase in feed rate. In theory, double the spindle speed means you can double the feed, but this particular machine is limited by its lack of power and rigidity. 
As such this might not be possible to achieve, you will have to try, and play by ear.

I was not impressed that the collet holder on my motor appears to be glued on. I suspect the set screws were not holding properly, maybe a stripped thread, so they just added some Loctite.
It does seem to be running ok so I have decided to just leave it, I’ll see how it goes I suppose.

This GS-775MR motor is the lesser of the two spindle upgrades available from Sainsmart, the other being a more powerful 300 watt option

This 300 watt spindle costs more but I would be careful not to add too much power to such a rickety machine. Personally I like the fact that the 3018 machine can be brought to a stop with a ⅛” end mill without the cutter breaking.
You save money not having to keep replacing your cutters!

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