New Quill Drive Design

[HimyKabibble]

I recently designed a quill drive, using a mounting concept I've never seen used before. I've seen the ones that mount to the tramming bolts. I did want that, as it makes tramming too difficult. I've seen the Elrod, but since I plan on selling these, I couldn't use their concept, as it is heavily patented, and I hear that Elrod is quite aggressive about pursuing anyone who *might* be infringing. So, I came up with a completely new concept that I think has some merits:

1) Does not interfere with tramming, or any other normal operation
2) Is extremely rigid.
3) Is extremely simple.
4) Makes installation and alignment very quick and easy.

As you can see in the model below, the primay mount is a plate that sits between the top of the head casting, and the bottom of the lower pulley housing. Insertion of this plate has zero impact on operation of the machine.

Installation is a simple matter to remove the motor and pulley housing, install the quill drive, optionally drill and tap a couple of holes to lock the plate to the head casting, then put the pulley housing and motor back. Alignment is accomplished primarily using the factory alignment surfaces milled into the front of the head, with adjustability on the lower bearing and the ballnut mounting to the yoke fastened to the quill. The upper bearings are 7202 A/C bearings, which provide thrust support. These bearings are totally enclosed. The lower bearing is a sealed 6202 radial bearing. All parts are aluminum, except for the yoke that attaches to the quill, which is steel. The ballscrew is a zero backlash, 20mm diameter, 5-pitch, driven by any NEMA34 motor through a 2:1 belt reducer. I'm using a servo motor on the prototype, but a stepper could be used just as well.

With luck, I'll have the prototype done in the next 7-10 days - I'm waiting for the materials to show up...

Regards,
Ray L.

[jmelson]

Originally Posted by HimyKabibble I recently designed a quill drive, using a mounting concept I've never seen used before. Ray L.

I think this is similar to what I did on mine (1J)
see http://jelinux.pico-systems.com/zaxis.html

Jon

[HimyKabibble]

Originally Posted by jmelson I think this is similar to what I did on mine (1J) see http://jelinux.pico-systems.com/zaxis.html Jon

Yup, similar, but different. Mine has the pulleys and motor at the top of the screw, and, of course, mounts differently. The pulleys/belt and ballscrew will all be totally enclosed as well.

I'm curious - does yours bolt only to the top and bottom flanges for the quill downfeed stop screw?

Regards,
Ray L.

[jmelson]

Originally Posted by HimyKabibble Yup, similar, but different. Mine has the pulleys and motor at the top of the screw, and, of course, mounts differently. The pulleys/belt and ballscrew will all be totally enclosed as well. I'm curious - does yours bolt only to the top and bottom flanges for the quill downfeed stop screw? Regards, Ray L.

Yes, I probably could have put the motor on top as well. It turns out not to be much of an inconvenience, about the only problem is when trying to get a caliper in there to measure the height of something. It is much easier to do that on the right side.

Mine is actually enclosed by plastic shields that come off easily for lubing. I put the encoder
directly on the leadscrew with a helical-slit coupler, and the tachometer is driven off a tiny
instrument belt.

Yes, there are just two custom bolts in the bosses for the stop screw. Those holes were pretty big, at least 1/2" as I remember, so I figured that was enough. I made these bolts custom to
have the full diameter of the holes filled, and to be as low-profile as possible, so as not to
restrict the quill travel.

Jon

[skullworks]

Elrod's Z unit limits travel to about 4.7"

Does yours allow for a full 5" usable stroke?

[HimyKabibble]

Originally Posted by skullworks Elrod's Z unit limits travel to about 4.7" Does yours allow for a full 5" usable stroke?

I've intentionally limited mine to 1/4" less than the maximum quill travel, in the name of stiffness. Travel is limited entirely by the dimensions of the "yoke" that attaches to the quill. In order to make that attachment as axially stiff as possible, I give up about 1/4" of travel, which leaves me with 4.95" on my machine. By removing just a little material from the bottom of the yoke, where it attaches to the quill, you could easily get that 1/4" back. The drive is also setup so the yoke hits the head casting at both ends of the travel, so that if run into the stop, the load is not put on the drive assembly, or, worse, the quill. This should make it virtually unbreakable.

Regards,
Ray L.

[skullworks]

So if you were to pull the quill and remove about 1/8" from top and bottom of the slot in the head casting you could have the full 5"?

[HimyKabibble]

Originally Posted by skullworks So if you were to pull the quill and remove about 1/8" from top and bottom of the slot in the head casting you could have the full 5"?

I'm not sure what limits quill travel in the head itself. Mine hits a hard stop at both ends, even without the bolt in the quill. But, on my drive, the limit on travel is determined entirely by the quill yoke. So, if you can modify the head/quill for longer travel, you'd only need to remove some material from my yoke, or worst case make a replacement yoke, to extend the travel to take advantage of whatever travel you have.

Regards,
Ray L.

[asuratman]

I recently designed a quill drive, using a mounting concept I've never seen used before. I've seen the ones that mount to the tramming bolts. I did want that, as it makes tramming too difficult. I've seen the Elrod, but since I plan on selling these, I couldn't use their concept,...

Hello Ray,
Will you release the prototype soon? Do you plan to sell plans or kits? Thanks.

[asuratman]

I recently designed a quill drive, using a mounting concept I've never seen used before. I've seen the ones that mount to the tramming bolts. I did want that, as it makes tramming too difficult. I've seen the Elrod, but since I plan on selling these, I couldn't use their concept,...

Hello Ray,
Will you release the prototype soon? Do you plan to sell plans or kits? Thanks.

[HimyKabibble]

Originally Posted by asuratman Hello Ray, Will you release the prototype soon? Do you plan to sell plans or kits? Thanks.

I'll bed making the first two units over the next 7-10 days. These two are for a Taiwanese clone mill, but I've got a friend with a real BP, so I'll be doing the design changes for that in parallel. The plan is to sell either a complete unit, with or without the motor. Selling plans would be far too much hassle, not enough return, and you can't really make the parts without CNC anyway.

Regards,
Ray L.

[HimyKabibble]

Finally making some progress on the build, but it's been a real comedy of errors, minus the comedy. I spent about a day making a big fixture plate that let's me make all the aluminum parts in one setup.

The first problem was the 3/4" plate I made the fixture from was not even close to flat - it had a 0.030" crown in it. So, I ended up having the face the whole thing. But, that didn't take too long, and it came out well. Would've been better if I had a face mill bigger than my little 2" one. Takes a while to do a 12"x36" with that!

Next, I found I'd been sent the wrong metal for a few of the parts. Naturally, I discovered this the day before Thanksgiving, *after* it was too late to call the supplier. I won't have that part for a few more days yet. So, I went about making the rest of the parts, and immediately ran face-first into a bug in Mach3 that had me dead in the water for several days, until I found a work-around. I should have a "fixed" version of Mach3 in a day or two.

My HomeShopCNC ballscrews showed up, and they're really nice. Tomorrow, I'll make the steel yoke that attaches the drive to the quill, providing I can round up a long enough endmill to do the inside and outside profiles - it's 1.75" thick.

Total travel of the quill will be 5.125" on my machine. It doesn't get any better than that! I was also lucky enough to have a friend with the BP he's rebuilding. He brought his head casting and quill by my shop so I could measure it up, and see how it compares to my Birmingham clone. Turns out, the differences are few, and very, very minor. I suspect all the parts will bolt up to a BP with no modifications, other than milling a small pocket in the backside of the thrust bearing block, to clear the serial number boss on the BP head.

Regards,
Ray L.