Yet Another Quill Drive Design

[HimyKabibble]

About a year ago, I built myself a quill drive, using a mounting method I've never seen anyone else use - it's simple, robust, and leaves the tramming bolts totally accessible. The entire drive mounts to a plate clamped between the two halved of the mill head, with the lower end supported by a single bolt through the boss at the bottom of the old quill stop screw. It works very well, is very accurate, and I've since made a couple more for friends, who are equally happy with the result.

The picture was taken before I'd made the covers to enclose the belt and ballscrew. The whole thing is now fully enclosed.

Here's the original build thread from last year: New Quill Drive Design

Regards,
Ray L.

[Desertrunner]

Hi Ray,
It came up well, I have one question did you remove the existing bracket that is bolted to the quill and replace it with your own. If so is the replacement one steel or aluminum?
I have heard that on some machines the bolt off that goes into the the quill comes lose as it not that strong. Have you heard of any problems?
Tony

[HimyKabibble]

Originally Posted by Desertrunner Hi Ray, It came up well, I have one question did you remove the existing bracket that is bolted to the quill and replace it with your own. If so is the replacement one steel or aluminum? I have heard that on some machines the bolt off that goes into the the quill comes lose as it not that strong. Have you heard of any problems? Tony

Tony,

I made a new yoke, from 1080. That is the weakest part of any quill drive that attaches to the quill in that manner (which, AFAIK, is ALL of them... There's really nothing else you CAN attach to.). I made the yoke fairly "tall", so it contacts the quill surface both above and below the bolt, so prevent the yoke from "tilting" relative to the quill under heavy loads (mostly if the quill is jammed, due to hitting a stop or the tool being driven into the table/workpiece). But, it has not been a problem on mine. The quill is pretty thick in that area, so I think it would take some serious abuse to loosen things.

Regards,
Ray L.

[Desertrunner]

Hi Ray,
Thats a good suggestion, I am limited on the top travel as I have a air tool changer so need to go to the top fully. Later I think I will change the attachment to the quill as well. I also noted that you went for coming down from the top with the support as opposed to me who used the 4 front bolts.
It is good to see different ways of doing the same thing. Its interesting you put a lower bearing on the ball screw. On the commerical Prototrak units they just have the one at the top.
Have a great day
Tony

[HimyKabibble]

Originally Posted by Desertrunner Hi Ray, Thats a good suggestion, I am limited on the top travel as I have a air tool changer so need to go to the top fully. Later I think I will change the attachment to the quill as well. I also noted that you went for coming down from the top with the support as opposed to me who used the 4 front bolts. It is good to see different ways of doing the same thing. Its interesting you put a lower bearing on the ball screw. On the commerical Prototrak units they just have the one at the top. Have a great day Tony

Tony,

I did start designing one that mounted to the tramming bolts, but after reading the alignment instructions for commercial units done that way, decided it would be a lot of hassle, if/when I needed to tram, or tlit the head.

I could've put another bearing above the pulley, but it seems easier, and stronger, to put it on the bottom. Functionally, I'm sure it doesn't matter, as long as everything is properly aligned.

BTW - I do have an unused commercial quill drive, if anyone wants to buy rather than build. It has a lovely HiWin ground ballscrew, and name-brand Japanese A/C bearings. It will accept pretty much any NEMA34 or 42 motor. PM me if interested.

Regards,
Ray L.

[Desertrunner]

That looks like it would suit John really well. If his bolt holes and mine are the same the left ones are 95mm apart vertically and the right ones are 100mm vertically.
Would that be the spacing of yours.
Tony

[HimyKabibble]

Originally Posted by Desertrunner That looks like it would suit John really well. If his bolt holes and mine are the same the left ones are 95mm apart vertically and the right ones are 100mm vertically. Would that be the spacing of yours. Tony

Tony,

They're standard BP dimensions - 3.85"/97.8mm vertical spacing, 4.6"/116.8mm horizontal spacing. The holes are over-size, to account for machine variation, and to allow perfect alignment of the whole assembly parallel to the quill.

Regards,
Ray L.

[Desertrunner]

Looks like I need to change that bracket from the ball screw nut to the quill. I think my one is not strong enough so I will do it like yours. I measured the movement in my current bracket last night and it was about 0.3mm of movment. It was all in the plate being to small.
Tony

[HimyKabibble]

Originally Posted by Desertrunner Looks like I need to change that bracket from the ball screw nut to the quill. I think my one is not strong enough so I will do it like yours. I measured the movement in my current bracket last night and it was about 0.3mm of movment. It was all in the plate being to small. Tony

Yeah, that's a tough piece to get right. I made mine extend about 1/4" above and almost 1/2" below the boss the attaching bolt goes through. It's machined so those two extensions make contact with the outside surface of the quill, and the bolt pulls them hard against the quill when it's tightened up. Seems to help, as I don't get any noticeable flex in normal operation - only if I jam the quill, and the servo tries to move it further.

Regards,
Ray L.

[Desertrunner]

Ray what is the thinkness of your bracket?

[HimyKabibble]

Originally Posted by Desertrunner Ray what is the thinkness of your bracket?

Overall, 1.25". The part that contacts the quill is about 1.15".

Regards,
Ray L.

[Desertrunner]

Originally Posted by HimyKabibble Seems to help, as I don't get any noticeable flex in normal operation - only if I jam the quill, and the servo tries to move it further. Regards, Ray L.

I personally think it would be better that when the axis jams the motor stalls, in other word have a lower powered motor. On the Prototak unit they have here a fair bit of damage gets done if some thing goes wrong. I think its got 600w motors on the Z axis which is overkill by a mile.
On the X & Y that I have you find that if you jam say a vice into the back of the mill (did that last night) the motor stalls and no damages is done.
Tony