[timberwolf5480]

Hi, I have a g0704 I am converting to cnc and I am gonna replace the motor and do the belt drive. I would like to keep the quill, I guess my question is, according to my research, the spindle pulley gets mounted with those two little m3 screws that hold the tach ring on to retain the function of the quill,

Has anybody ever broken those two bolts while milling?

Thanks for the input.

[109jb]

I use those 2 tiny bolt on my belt drive using the stock motor. Just the other day I was running a hand coded job and due to my own programming error the 3/8" end mill plunged into the stock and stopped the spindle almost immediately. The tiny bolts held and I kept running the machine after that without issue.

[timberwolf5480]

That's alright, I am going to run as is after I get the new motor on, eventually I will replace the spindle bearings, when I do, I have a plan to add a key to that part if all else fails. Thank you for the input.

[109jb]

Forgot to mention. One thing I actually did this afternoon was I made a cupped washer to put over the splined end of the spindle shaft where that cap for the drawbar screws on. The drawbar cap can then be threaded on and use to convert the quill type shaft to a no-quill drive. The benefit of this is to make things a bunch quieter when I don't need the quill function. There are times when I need it and times when I don't. I use the quill on quicky jobs primarily when I'm using the mill as a drilling positioner. For my jobs I design on CAM I don't need the quill. It is a whole lot quieter with that on there. Next I will make a nut on the lathe to use instead of the drawbar cap.

[timberwolf5480]

Forgot to mention. One thing I actually did this afternoon was I made a cupped washer to put over the splined end of the spindle shaft where that cap for the drawbar screws on. The drawbar cap can then be threaded on and use to convert the quill type shaft to a no-quill drive. The benefit of this is to make things a bunch quieter when I don't need the quill function. There are times when I need it and times when I don't. I use the quill on quicky jobs primarily when I'm using the mill as a drilling positioner. For my jobs I design on CAM I don't need the quill. It is a whole lot quieter with that on there. Next I will make a nut on the lathe to use instead of the drawbar cap.

Would anyone know what the threads are on that drawbar cap? That's just something I've been thinking about for a couple of years now too.

[mcardoso]

Threads are an oddball metric size. Nothing nominal. I just made a drawbar top hat on my lathe for this. Had to take measurements on crest and over wires. I'll pull those out for you, but I would strongly recommend you measure your own as there is a lot of deviation from machine to machine. Close-ish to a M20 x 1

[109jb]

One note of caution. I ended up not using the drawbar cap to lock things together up there. The reason is because I tightened it up and noticed that I couldn't get the same RPM as I used to. Dorked around trying to figure it out which wound up running the spindle for 10 minutes or so, I then happened to touch the spindle and it was very very hot. Pulling on the top of the drawbar was putting too much load on the lower spindle bearing and it heated up.