Mill Z axis crank wheel

[Bony]

This idea came to me when I had to make repeated small increments to the depth of milling a part. The wheel is an inexpensive steering wheel from a power boat, found in any boating/marine/ship chandlers shop. The rim of the wheel is always just at hand, rather than fumbling for the crank and if you chose a steering wheel of larger radius than the crank handle (normally supplied with a small mill) very small height adjustments to the mill table are much easier to make. In addition it's also easier to lift the table with minimum effort when its loaded up.

The solution for attaching the wheel to the square shaft on the mill is to made the female part in two halves, and to fasten it with a simple knob which forces the halves together onto the shaft.

I hope the photos show all that you'll need to make one for yourself.



Feel free to email me if you need further explanation. All the dimensions and way you proceed will depend on the materials you have at hand and the size of your mill, and sorry I don't have any drawings.

[rctoywizard]

Very cool idea!
I put a Go Kart stearing wheel on my 23" arbor press for the left side. Helped me out a ton too.
I got to try your idea.
Thanks again

[Toolmaker51]

If there is clearance, I'll try a flat motor bus wheel and a spinner knob or folding tapered handle. My K&T was built with one, yet never thought of affixing that human engineering elsewhere! Ergonomics are a real aide to us so aged.

[tonyfoale]

For anyone who wants to attach an alternative winding device to a Bridgeport here are the important dimensions for making a mating thingy.



I did the ultimate in geriatric aids, I added a motor, so the extent on my effort has reduced to setting a direction switch and pressing a button. No good for precision adjustment but the Bridgeport has the quill for that, and I did it to be able to still use the handle. Always seeking the easy way I also added some helper springs as in my previous post at http://www.homemadetools.net/forum/k...5951#post82823 which really makes the effort minimal.

[Toolmaker51]

Tony's powered knee and gas spring load reduction makes me wonder...Lathes and jigbore foundation of accuracy is due to the ways. Knee ways have 2-4x bearing surface of lathe carriages. A vari-drive DC motor driving a reduction gear could be a dynamite modification. For starters, many have roughed a bore cranking manually in lathes or mills. The only difference would be figuring IPM [inch per minute] vs. FPR [feed per revolution]. Knee mills are limited to something like .001 to .006 per rev. Good for small holes to maybe 5", with standard tooling. Powering the knee would mean infinite range more or less, especially in proper finish. Many an occasion required a lathe, when labor-wise setting a mill for multiple parts would be the edge.
Tony's adapter even makes it portable.

P.S. edit. I've seen one occasion of an energetic young 2nd shift operator + cordless drill vs knee of a turret mill. He has spotty mechanical ability; injudicious in application of rpm, not to mention clamped directly in the chuck, sans adapter to apply torque. The job needed many Z changes.
In three days hand-crank wouldn't fit the shaft. After dressing equivalent pipewrench marks off, the lead screw/ nut combination were found to be scored beyond accurate use, in same range of the three days work. Repair cost exceeded the initial profit of labor saved by 500%.

[tonyfoale]

Tony's powered knee and gas spring load reduction makes me wonder....... A vari-drive DC motor driving a reduction gear could be a dynamite modification. .................
Tony's adapter even makes it portable.

Actually, the adaptor drawing is not mine, I found it on the net and it was designed to be used with a cordless drill. For me it was just a nice reference for the dimensions of the Bridgeport dogs.
I intended to make the motor drive through the dogs but then I saw how I could fix a pulley behind them and still retain the ability to use the original handle if I needed to make a fine adjustment. Perhaps I should take some photos and make a post

I am using a DC motor but I decided that single speed was enough so I feed it through a step down transformer, which I had, with a bridge rectifier between motor and transformer. The speed could be a little higher but that is what the transformer provides and in any case it is far quicker that winding by hand. Having used it for a couple of years now I am quite happy with a single speed, and have never needed to use the manual handle.

I would highly recommend some form of counter balancing the weight of the knee and table. It is a win/win modification. For a small mill I'd use an actual counter weight with a cable over a pulley, that enables you to exactly balance the weight throughout the movement range making moving the knee assembly effortless whether manual or motorized. It is easy enough to cast a concrete lump for the counterweight, throw in any steel or lead scrap to reduce the needed size. I use counter weights on a couple of drill presses which don't have a rack and pinion. However, that is hardly practical with mills of the Bridgeport's size, hence my use of the pneumatic spring units which give reduced help as they become extended (table raised), but owt's better than nowt.

[DIYer]

Thanks Bony! We've added your Z Axis Crank Wheel to our Machining category,
as well as to your builder page: Bony's Homemade Tools. Your receipt:

Z Axis Crank Wheel by Bony

tags: wheel, mill

[Toolmaker51]

Actually, the adaptor drawing is not mine, I found it on the net and it was designed to be used with a cordless drill. For me it was just a nice reference for the dimensions of the Bridgeport dogs...
I would highly recommend some form of counter balancing the weight of the knee and table. It is a win/win modification. For a small mill I'd use an actual counter weight with a cable over a pulley, that enables you to exactly balance the weight throughout the movement range making moving the knee assembly effortless whether manual or motorized. It is easy enough to cast a concrete lump for the counterweight, throw in any steel or lead scrap to reduce the needed size. I use counter weights on a couple of drill presses which don't have a rack and pinion. However, that is hardly practical with mills of the Bridgeport's size, hence my use of the pneumatic spring units which give reduced help as they become extended (table raised), but owt's better than nowt.

A counter-weight is feasible. In use by variety of machine tools; especially in sliding heads of jigbores and drills like the Cleereman, operating in the hollow columns. They use a sprocket and 1 or 2 rows of roller chain connected at the upper end of head, weight of course at other end.
None are neutral or weight cancelling, just reduction so the head doesn't float upward.
In the case of a leadscrew raising a machine element, the same principle would apply. Less effort is nice; still want a leadscrew to bear load for backlash compensation. Otherwise the dial or readout will be useless. Lazy google search indicates a 9 x 30 knee & table at 400-460 lbs, 10 x 54's at 500. Seems reasonable target, considering weight of vises, rotabs, indexers etc. Designed load on 9 x 30 is 750lb workpiece.
A pair of flanged bearings outside the column would support a shaft and sprockets through it. They have self aligning feature built in. Place high enough for full upward travel.
A pair of standoffs on the knee would anchor the roller chain. That would ensure upper end of knee contacts column, leverage presses lower end into contact. Place high enough so a pair of weights operate without contacting machine base or floor.

[Toolmaker51]

And there was another way; moving heavy machine elements. A gullible apprentice.
"Crank this while I observe _ _ _ _ " [insert any excuse here].

[Gary A. Wills]

Probably cheaper then machine hand wheel. I like it good job , love thinking out of the box. Thanks