Limited Quill Travel - Pm-932m

[GarageWrench]

Indeed. The quill extension is kept as short as possible during milling operations.

Just wondering, on a mill like a Grizzly G0730, how much movement of the knee is there in say one revolution of the knee hand wheel? Also can you feed a piece into the cutter with the knee, just like using a quill?

 

[wrmiller]

On my friend's BP clone (the one in my avatar) I always used the knee for plunge/pocket cuts. More precise. I don't remember the numbers though, sorry.

But on a bench mill we have no choice but to use the quill for plunge/pocket cuts. Fortunately for me I very seldom need to do them and when I do they are pretty shallow.

 

[tmarks11]

Just wondering, on a mill like a Grizzly G0730, how much movement of the knee is there in say one revolution of the knee hand wheel? Also can you feed a piece into the cutter with the knee, just like using a quill?

You use the knee for precise movements of the cutter against the workpiece, with the quill fully raised and locked. Like Bill said, this gives you very precise control of how deep you plunge the end mill, etc.

You generally don't use the quill except for drilling and boring.

Most bridgeport mills have 0.100" movement of the knee per revolution of the hand wheel. I think the G0730 is actually 0.125" per revolution.

 

[Rex Walters]

Rex, on yer G0762 there is no motor for the head up n down, has that been an issue or an inconvenience?

Buck

Sorry, I've been traveling and just noticed the question. The manual crank for the head on the G0762 is definitely an inconvenience (I use other words in the shop ;-). Especially since unlike a full sized mill, the crank is on the left of the column in the rear, not in front on the knee, and you've got to lean over your bench to get at it. I've got an old motor I may repurpose someday as an automatic cranker.

On a bridgeport or full size mill, I agree with Tim that you would usually only use the quill for drilling/boring. On a bench top mill, though, there is no dial on the Z axis except on the quill, so you're forced to use the quill while milling (unless you have a DRO in Z). Basically, when milling I try to minimize the quill extension: crank the head down until the cutter is almost touching, then use the dial on the quill to touch off (or touch a feeler gauge/cigarette paper), then zero the dial on the quill and keep extending the quill until you're at depth. For anything but very light cuts I have to use the quill lock to ensure the depth doesn't creep up.

Overall, I'm quite happy with the mill, but in addition to the manual crank in the back, other annoyances include:

• max spindle speed of about 2500 RPM,
• no spindle lock (need two wrenches to tighten the drawbar),
• "inconvenient" to tram in the nod axis (shims),
• the levers on the gib locks are too long and interfere with way travel in both X and Y (had to grind them shorter),
• the gib locking knobs are made of some soft pot metal (I've already stripped the one to lock the Y axis),
• and the zero locking knob on the Y axis interferes with way travel (I just removed it since I use a DRO).
• surprisingly few good places to mount holders for lighting

 

[GarageWrench]

Sorry, I've been traveling and just noticed the question. The manual crank for the head on the G0762 is definitely an inconvenience (I use other words in the shop ;-). Especially since unlike a full sized mill, the crank is on the left of the column in the rear, not in front on the knee, and you've got to lean over your bench to get at it. I've got an old motor I may repurpose someday as an automatic cranker.

On a bridgeport or full size mill, I agree with Tim that you would usually only use the quill for drilling/boring. On a bench top mill, though, there is no dial on the Z axis except on the quill, so you're forced to use the quill while milling (unless you have a DRO in Z). Basically, when milling I try to minimize the quill extension: crank the head down until the cutter is almost touching, then use the dial on the quill to touch off (or touch a feeler gauge/cigarette paper), then zero the dial on the quill and keep extending the quill until you're at depth. For anything but very light cuts I have to use the quill lock to ensure the depth doesn't creep up.

Overall, I'm quite happy with the mill, but in addition to the manual crank in the back, other annoyances include:

• max spindle speed of about 2500 RPM,
• no spindle lock (need two wrenches to tighten the drawbar),
• "inconvenient" to tram in the nod axis (shims),
• the levers on the gib locks are too long and interfere with way travel in both X and Y (had to grind them shorter),
• the gib locking knobs are made of some soft pot metal (I've already stripped the one to lock the Y axis),
• and the zero locking knob on the Y axis interferes with way travel (I just removed it since I use a DRO).
• surprisingly few good places to mount holders for lighting

Thanks Rex, great info indeed. I was wondering how much movement in the head up/down do you get with one revolution of the crank?

On your G0762 with a max of 2500RPM, it looks like that machine has one of the highest rated speeds of any machine its its category, being a square column mill.

Im taking a road trip to Grizzly in a couple weeks to look at the selection of mills, hope it s solves my issue of trying to decide witch mill to order.

Thanks for your time sir, please keep posting and add some pic's!

Buck

 

[Rex Walters]

I'll measure the travel tomorrow and create a new thread in a more appropriate forum (with pictures). Without a dial on the crank, I've never used the crank for anything more precise than about +/- 0.500".

If I measure the travel, I'll pretty much be obligated to jury rig a dial of some sort.... ;-)
--
Rex

 

[Rex Walters]

To answer the question, it appears to move 3mm (0.118") per revolution of the crank. So much for an easy job of making an inch dial...

I've stopped hijacking this thread. Any further comments/questions regarding my G0762 should go to my thread on the Grizzly forum.
--
Rex

 

[Bray D]

No worries on the thread jack. I said everything I wanted to say in my original post, haha. This thread is simply for awareness - if it happens to get peppered with some other useful information then that's all the better!