Thinking of a couple mini mill modifications...

Zoltan

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Apologies if this is the wrong forum for this post.

So I finally added a Grizzly mini mill to my basement workshop (along with a Keurig). It's my first mill and I'm just getting used to how it works. I have two ideas for modifications, and would like to get your opinion.

1. The mini mill I have has a MT3 spindle, and I really don't like hammering the draw bar to release it. It just feels wrong. The top of the spindle is ringed by the 4 mounting screws for the motor mount. I was thinking of essentially making a "bridge" between two of the mounting screws and over the top the draw bar. In the middle of the "bridge" (bracket?) I'd drill a hole and then put a bolt in it head down and secure it in place with two nuts. The bolt's head would be adjusted so it sits just above the draw bar's top. This way when I loose the draw bar it would hit the bolt and as I keep loosening it, it would push the tool out of the spindle.

Fear my MS Paint skills:
mill.jpg


2. I'd like to add a power feed to my X axis. Looking at the mill it seemed like the easiest way to do it would be to turn a V-groove into the OD of the hand wheel, attach a bracket for a motor, and then just rig a speed control of some kind. It's wouldn't look pretty, but it seems like it would work well.

mill.jpg
 
hammering the draw bar is how its done. i have to hammer on my iso 40 spindle too. yesterday i hammered the cap onto the wheel bearings on my car and the hammer i had to use was pretty big. why dont you put an electric impact wrench on there and have automatic release?
 
Don't think of it as hammering. Think of it as tapping gently until the collet loosens and slips down.

Better, right?
 
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The best mod you can do to your mini mill is to buy or build a belt drive for it.

If you haven't already, get yourself an MT3 collet chuck and then the only time you'll need to hammer the drawbar is when you want to swap over to the drill chuck.
 
You don't have to beat it to death. I have R8 taper on my mill and a single sharp rap with a plastic, brass, or lead faced hammer is enough to release the taper. On my MT3 lath, I use a piece of broomstick and the same hammer to release the taper, while holding a rag over the center to catch it when it releases.

Chuck
 
The 1st mod I did was the air shock for the head support. It gets rid of the torsion spring, and you get more Z-axis travel.
I just did the belt drive, it sure makes it quiter and seems to run smoother. I thinks a DRO is a must.
 
My X2 mini has the MT3 spindle. A sharp whack on the bolt is the required method. I use a copper hammer or a large dead-blow. I had to replace the drawbar a few years ago because the original didn't have enough thread length and the threads on the bar stripped. I used a grade 8 bolt to make a new one with more threads inside the MT3.

+1 for David's comment on replacing the gears with belt drive. Don't wait for the gears to explode.


Edit: Fixed spelling error.
 
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Why not eliminate the need to use the drawbar?

Best tool I got for my mill was an MT3 ER25 collet chuck and set of collets, now no need for a drill chuck or end mill holder.

I chose er25 because it was 1/2 the price of er32 and figured the 5/8" collet size would be the max I would normally use. The chuck and full collet set was only around $75.
 
Best tool I got for my mill was an MT3 ER25 collet chuck and set of collets, now no need for a drill chuck or end mill holder.

Do you lose much headroom with the ER collets? My mini mill is R8, but I've been thinking of getting an R8 ER25 chuck and trying ER collets.

One thing I don't understand about ER collets: Do you have to remove the ER nut every time you change a collet?
 
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