Problems Mounting DW660 on Primo

Today is started to try mounting a DW660 on my primo instead of a sharpie using the V1 DeWalt 660 -Primo files from github . I ran into some issues following the directions and so am posting here. I looked for a similar thread since the DW 660 is common but didn’t see one.

I’m wondering if I’m overlooking something or if DeWalt has released a new version with mechanical changes that require changes to the mount or process.

First - confirming I got the right files, instructions, and router:

The router had a depth limiter I was able to remove which seems unneeded with the MPCNC.

When I started the spindle was centered on the opening for the collet.

When I rotated it I noticed it was off-center and thought that’s probably not right.

I then investigated in more detail to see that it was keyed to only mount flush in one orientation.

There are bosses with draft of different sizes that function as locators and a key. When you turn the cap 90 degrees these interfere with seating the lower portion of the router.

This could be defeated with a saw. Cutting them off but that’s not a step in the instructions and unlikely to have been overlooked by the author if it was required.


The lower portion has evenly spaced ridges around it. The “Bottom mount” part has a different pattern.

The directions referenced the spindle lock. I’m not sure if that is the button labeled 1 or 2 on my router. #2 can rotate without unscrewing and rotating the lower portion of the router. These were not shown in the photos on github or the Prusa site that offered the DW 660 mount for download.

So, I’m hoping someone can comment if I’m using an old rev of files… or if my 660 doesn’t match the unit the part was designed for… etc… Thx

Read fully before proceeding to avoid breaking DW660.

It’s not just the yellow cap you need to remove. The motor assembly needs to be pulled forward and rotated 90 degrees and then the cap put back on the way it was.

If you pull the motor out more then 1/4 inch +/- a little the brushes will pop off the top of the motor. If you pull to hard and 1 gets caught it will snap - I speak from experience.

My recommendation it that you remove the top cover (the other end) and watch the two brushes as you slowly pull the motor forward. Be careful there are a lot of parts loose now.

While watching the brushes I was able to rotate the motor without them catching or popping off.

Another note: the spring on the spindle lock (just under the yellow cap) can launch itself when just sitting there open. Mine shot across the shop. I was luck to find it.


Yes brushes very troublesome the spring was almost as hard to find as the clip for the probe i left connected to the bit when I powered on the 660 :grinning_face_with_smiling_eyes:

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Thanks for your help.

The spring went rogue both times I opened the router but luckily I found it both times.

I rotated the black piece that was the next layer into the router 90deg and then reassembled the router. I watched 2 YouTube videos about brush replacement which disassembled the other panel of the router case on the power cord end. That let me see what to look for on that end and try to avoid disturbing during the rotate operation.

I also figured out the “Bottom Mount 660 Primo” piece mates up with a yellow plastic part of the case below the rotating part between the #1 and #2 buttons and part of my problem was not trying to mate it with the flat side up (that was on the 3D printer bed when the part was printed). Before I was trying to mate it up with that black piece and mate it upside down.

I think I got it oriented as intended now.

I broke the nut capture on one of the pieces and am reprinting and will try again tomorrow.

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I just spent far too long trying to figure this out! I think the root cause was hat I had the bottom mount positioned upside down. Once I removed the yellow cap I tried all sorts of ways to just get it to fit. Only when I turned it upside down did it assemble smoothly and lock into place.

So far this has been the most tricky part of the build for me. Glad (I think) I have a solution to move forward :slight_smile:

That being said, have you come across any documentation for rotating the motor 90 degrees? I am about to give it a shot on my own. Would definitely feel better if there was a tutorial I could find somewhere. :grimacing:

Did you find your answer. It seems to be at the bottom of this page. I hope to be trying soon. MPCNC_Primo_Tool_Mounts/DeWalt 660 - Primo at master · V1EngineeringInc/MPCNC_Primo_Tool_Mounts · GitHub

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Wow. I find it incomprehensible that nobody has simply modded a mount (like this one for the burly: MPCNC, Modified Burly DW660 Lower tool holder by rjallison81 - Thingiverse) to allow for a different orientation so that I don’t have to void the warranty on my DW660… Maybe someone has, but I have not been able to find it. I’m going to try printing just the the lower lock chopped out of the STL for the burly version and seeing if I can re-orient the DW660 so the cord doesn’t face the wrong way.
EDIT: That’s a no-go, doesn’t match up with the already printed primo lower mount. Now looking to use the burly tool mount plate with a different mount.

I don’t know anything about the specific issue you are addressing, but the Burly mount plate will fit on the Primo. You will either have to use the Burly nut traps, or you will need drill out the holes a bit to get the larger machine screws to fit for the Primo nut traps. If you have not already printed out the Burly plate and plan on drilling out the holes, I recommend adding some extra perimeters to the holes.

The one downside to using the Burly mount plate is that the router will be a bit more cantilevered from the core. This is one reason Ryan has mentioned the design changes he made for the Primo.

So, I ended up pulling the burly mount plate into blender and re-working the holes to fit the Primo screws. I’m using M5 Hex cap screws as not to have to make those countersink depressions too large. I don’t have the DW660 mounted on it, as I’ve opted for a dremel mount for now to do some other work and the build isn’t 100% complete (very long story, short version: Life), but will post back when I do.

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