Motorized mill head lifting gear

[Loose nut]

I have a RF45 type mill (square column with dovetail) and I would like to put a head raising motor on it so I can bore holes under power, for a better finish.

Most of the one I have seen with this feature have the motor built into the top of the column connected to the drive screw that does the raising. A less complex, read less likely to screw up something expensive method, would be to replace the crank handle with a sprocket and drive it with a small motor mounted on the back of the column.

Now for the fun bit, how big a motor will I need??? I can turn the crank to raise the head fairly easily but I have no idea how much power it takes to lift the mill head.

I was thinking about a sewing machine motor, they are about 1/20 HP variable speed and reversible which is necessary, with around a 4 to 1 reduction driving the raising gear through the sprockets.

Do any of the greater brains here think that it would be powerful enough to do the job. Any better ideas. This is a budget job so expensive commercial ideas like buying the proper gear isn't going to fly, sorry.

 

[bearcar1]

LN. I have seen adapters made that were merely large 'sockets' that fit on the Z screw replacing the crank handle. The opposite end was a stub that the user could chuck up in a power drill. I do not know if that is the arrangement that you were thinking about or not.

 

[Kermit]

You might be moving that head pretty fast with only a 4 to 1 reduction.

Think twenty to one or even as high as fourty or fifty.

You want to go from the high double digits (30-60) revs per SECOND down to one rev a second at most and probably a little slower.

Other than that, I'm useless to you! ;D
Kermit

 

[crankshafter]

You might be moving that head pretty fast with only a 4 to 1 reduction.

Think twenty to one or even as high as fourty or fifty.

You want to go from the high double digits (30-60) revs per SECOND down to one rev a second at most and probably a little slower.

Other than that, I'm useless to you! ;D
Kermit

Look at this.Maybe............. :: :noidea: http://bbs.homeshopmachinist.net/showthread.php?t=34361
CS

 

[Loose nut]

The motor in question is variable speed so it can run slow enough but will it have the power to do the job.

 

[Holescreek]

I have been thinking of motorizing the knee on my Bridgeport. I know I can buy one that bolts on for several hundred dollars but what'd be the fun in that?
I have a 1/30th HP AC motor with a 120:1 gearbox on the end. Motor spins around 1500rpm which sould give me 12.5 RPM with some torque. That's too slow as is, might have to change sprocket sizes to speed it up.

You want variable speed for boring. I'd look at some 24VDC motors that you can control with a PWM board. What is the weight you want to lift, is there a counterweight, (if not you might want to add one), can you measure the required torque with a torque wrench? Just some ideas...-Mike

 

[Holescreek]

Check this motor out: http://www.allelectronics.com/make-a-store/item/DCM-2445/24VDC-450W-MOTOR-W/-PLANETARY-GEAR/1.html

Add a Pulse Width Modulation (PWM) board for speed control and you have a boring machine. I built my PWM board from a kit available here: http://www.electronickits.com/kit/complete/motor/k166.htm
If you can solder it up yourself you can save $24 by getting the kit.

 

[BobWarfield]

My Industrial Hobbies mill has a particularly heavy head, so I sympathize.

I would be really tempted to create a system that works more like the CNC conversions do. The manual mills have a bevel gear arrangement to connect the crank at right angles to the leadscrew. There is quite a bit of slop in that whole thing--you have backlash in the main leadscrew and more backlash in those bevel gears.

It would be really cool to be able to use that drive as a power feed for boring, I agree. Being able to position that Z fairly accurately will have other uses too, I'm sure. If you have a DRO on it, and slow enough motion, it might be preferable to the quill for a lot of operations, allowing you to lock down the quill for rigidity. I know this is how I use my mill now that it is CNC'd.

To make this all happen, the leadscrew would need to be driven at the top with a belt driven motor. It might be worth looking at pix of how the CNC crowd are running the Z-axis motors on their mills.

Cheers,

BW

 

[Loose nut]

To make this all happen, the leadscrew would need to be driven at the top with a belt driven motor. It might be worth looking at pix of how the CNC crowd are running the Z-axis motors on their mills.

This seems to be the preferred method if it is installed at the factory but I was looking at a simpler method which would minimize the chances of my screwing up the machine. The head really isn't that hard to raise with the crank, I.m more interested in doing it for boring.

 

[kvom]

When I use the boring head on my BP I user the slowest power quill feed at .0016" / rev. Since boring is usually a low RPM process, the head would need to descend quite slowly.