Spindle Options and fit

Hello everyone,

So I have my MPCNC operations and ready to go, but I need to pick a spindle. I was hoping to get a large 3 HP spindle with a VFD controller, but the bolt holes are 3.18 inch width and the MPCNC looks to be about 2.5" between the roller bearings that the spindle would mount to. I know I can design something to space it out a little and get it to fit. I wanted to ask if anyone else has mounted a larger spindle like this to their machine? How did you mount it? And if you had any problems with the heavier weight motor?

I’m looking to cut aluminum so I thought, what the hell, why not just get the biggest, badest spindle I can!

Hello Brian, welcome to the forum! Good job on setting up your MPCNC. If you want to mill aluminium, I don’t think the spindle is the main concern, I would think it’s the size of the build that would impact the cutting quality. (the bigger the less rigid) You’d be suprised how a 2HP machine (like the Dewalt or the Makita) can perform! If you are looking for some high-grade CNC that can churn through metals like butter, the MPCNC is the wrong lane. The MPCNC is super capable, you just have to adjust your mindset and expectations more carefully in terms of feedrate and DOC.

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I hear you. I’m not trying to build a Hass. Just want to cut a little aluminum and mostly wood and plastic. I bought a 3HP VFD spindle. I’ll try to update a post after I get it running for a while.

Thanks for the advice!

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3hp sounds huge to me, I’m cutting aluminium fine with a 500w unit.
I’d be careful with such a powerful spindle you’ll be able to destroy the rest of your machine in no time if it gets out of control.
I learnt this the hard way.

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I have a 65mm dia., water cooled spindle with a vfd. I printed a special mount for it. Works great but I had to add springs to the Z guides it so it didnt sink when Z was de-energized at the end of a cut. Works very well.

You have to watch the weight of the spindle with regard to acceleration, core, sagging etc.

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I ordered a 80mm dia. spindle. Probably heavier than yours. Thanks for letting know about the weight. Sounds like I’ll probably need to adjust the z motor to hold it. Springs sound like a good solution! I’m committed now and will find a way to make it work. Thanks for the comment.

This is what i did on the Burly setup i have - also, be careful about the compression length. fully compressed the springs will have a lot of resistive force so you have to size the springs correctly.

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What diameter spring? Looks about .90" thick x 1.50" spiral OD. Maybe 4 or 5" tall. Do you have any issue with springs moving around? Do you think making a seat like your cad model is necessary?

Here is my 80mm Dia. 2.2kw VFD spindle setup that I made a custom 3DP mount for as shown. Looks like my spindle is sitting too low. At the highest point on the Z axis it only gives me 1/2" clearance from the table. I plan on putting a 1/2" spoil board and then the cutting material thickness so I’m going to have to remove Z tubing and redrill holes to raise height accordingly. I want my top height to be 3 - 3.50" above the table and bottom out a 1/4" above the table.

I did notice that the weight of the 11lbs spindle does want to fall more than normal. My spindle holder kind of makes it hard to fit a spring as Gary shows and when I raise the spindle mount it will interfere even more. I’ll have to think on this but I should have a few inches to install some kind of spring assist after looking in to it more.

IMG_7029 IMG_7047

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Brian I used these springs

Hey Brian, I’m looking to do the same thing as you except a 1.5kw water cooled. Do you happen to have that 3DP of that tool holder you can share with me? Thanks.

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emailed it. Forum does not allow upload of files.

By any chance do you still have the file to email? Also, how did it turn out?

You can upload them zipped.

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80 MM spindle holder MpCNC.zip (1.1 MB)
Files attached!

Mike, it works super well. It seems very strong. Adds more rigidity to the whole z drive tubings.

Did you have to use the springs for the weight when the Z motor de-energizes?

I did not use a spring because the design blocks the tubing area where Gary put one. It’s not a big deal to me. Sometimes it does fall down when de-energized but I’m just careful with turning it off. Anytime the motors are on it has no problems holding.

Let me know if you find a solution for that.