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davidwdyer
01-09-2013, 10:18 AM
On this forum I've seen many different slotters for the lathe. Most were manual types.

I think some were hydraulic. We even discussed air over hydraulic methods at one point.

What I am wondering is if a powerful slotter for the tool post of the lathe could be make with

some kind of threaded rod/bolt powered by an electric drill.

Would a fine thread give enough force? Would some gears have to be incorporated?

Any thoughts, experiences or designs out there?

davidh
01-09-2013, 12:39 PM
i was thinking of a long stroke sawzall or a crankshaft driven by a cordless drill. still thinking about both. . .

davidwdyer
01-09-2013, 01:26 PM
I would think that what you mention would take off only a very small bit at a time.

They would also appear to be limited as to their stroke.

I did make one once for a friend with a long handle for leverage, but I would like something

which applies more force.

The Artful Bodger
01-09-2013, 01:45 PM
Here is my power slotter made from a cheap drill press...

http://farm2.staticflickr.com/1244/5157486308_00270748d4.jpg (http://www.flickr.com/photos/25239206@N06/5157486308/)
geared slotter (http://www.flickr.com/photos/25239206@N06/5157486308/) by aardvark_akubra (http://www.flickr.com/people/25239206@N06/), on Flickr

Toolguy
01-09-2013, 03:03 PM
Maybe a crankshaft/flywheel arrangement that has a T slot in the flywheel to adjust length of stroke.You could put a pulley groove in the flywheel and use a small electric motor with a small pulley to gear down the RPM.

davidwdyer
01-10-2013, 05:32 AM
I'm giving this a little bump to try to get some relevant responses.

Can it be that no one on the forum ever made/seen/or heard of a slotter powered by using threads????

darryl
01-10-2013, 06:49 AM
Offhand, it would seem to me that a lot of power would be wasted between the threaded rod and the nut if decent speeds were to be attained. I think it will wear out early. I do think that you could get the force required from it though.

Maybe it could last reasonably well if the mechanism was sealed inside a chamber where the threaded shaft and the nut were immersed in fluid- say way oil or diff lube.

One of the challenges mechanically would be speeding the rotation of the shaft one way, then reversing, etc. I just think that a lot of the available power is going to be used up just operating it, creating heat and wear, with only a fraction of the power going into the chip-making.

But you are talking about a slotting mechanism to use on a lathe, not a full-blown shaper. It might be fine as a tool that doesn't get a lot of use. I don't think you would ever see an industrial or commercial machine made this way.

gwilson
01-10-2013, 08:24 AM
Bodger,is that a true "slotter",or a simple milling attachment for external grooves? What am I not seeing?

davidwdyer
01-10-2013, 10:43 AM
Offhand, it would seem to me that a lot of power would be wasted between the threaded rod and the nut if decent speeds were to be attained. I think it will wear out early. I do think that you could get the force required from it though.

Maybe it could last reasonably well if the mechanism was sealed inside a chamber where the threaded shaft and the nut were immersed in fluid- say way oil or diff lube.

One of the challenges mechanically would be speeding the rotation of the shaft one way, then reversing, etc. I just think that a lot of the available power is going to be used up just operating it, creating heat and wear, with only a fraction of the power going into the chip-making.

But you are talking about a slotting mechanism to use on a lathe, not a full-blown shaper. It might be fine as a tool that doesn't get a lot of use. I don't think you would ever see an industrial or commercial machine made this way.


Isn't that just what moves the carriage on a lathe? Just an ACME screw? If they don't wear out quickly, why would a slotter unit?

My original post called for using a drill motor for moving the screw. This could easily have variable speeds and fast reverse.

RussZHC
01-10-2013, 02:07 PM
How about this: http://www.ebay.com/itm/Master-Lathe-Model-B-Broach-Broaching-Keyway-Cutter-/200875923281?pt=LH_DefaultDomain_0&hash=item2ec5235751

been scratching my head since it went up as to how to best go about attaching/holding/using...perhaps some pieces/parts are missing? The very basic movement of cutting edges I sort of think I get but how do you move it deeper under control...assuming I am correct in thinking it is some sort of rotary>>>reciprocating motion

The Artful Bodger
01-10-2013, 02:21 PM
Bodger,is that a true "slotter",or a simple milling attachment for external grooves? What am I not seeing?

OK, it is a small drill press with a modified base to attach to the lathe cross slide. The drill chuck has been removed and replaced by a small gear which drives a larger gear on a shaft that turns between two bearings, one on the drill head and one near the foot of the drill. There is a square hole through this vertical shaft through which a short piece of HSS tool steel is clamped by a set screw.

The HSS tool is ground according to the width of slot required, maximum 0.25".

The workpiece is in the lathe chuck and the lathe spindle is locked by a indexing device on the other end of the spindle.

Cuts, slots, can be made across the end of the workpiece (maybe making a dog clutch) or along the shaft as in making a keyway or spline.

Feeding is done my moving the cross slide/carriage.

It could be that I dont really know what a true slotter can do?

http://farm5.static.flickr.com/4017/4622455225_81596bfa7d_o.jpg

The Artful Bodger
01-10-2013, 02:29 PM
I have made an indexer to go with the vertical spindle:-

I made a pile of bits...
http://farm5.static.flickr.com/4037/4628298349_600e239ab5_o.jpg



...which put together look like this..
http://farm5.static.flickr.com/4051/4628298353_35269e0607_o.jpg


...the aluminium bit screws into the end of the spindle and the small hole goes over the stud that secures the gear case cover..
http://farm4.static.flickr.com/3315/4628298355_95f9b55acb_o.jpg

One detail which you cannot see is that I added a nut on the gear cover stud inside so that the knurled knob has something secure to screw down on to, not just the springy fibreglass cover.

darryl
01-10-2013, 11:58 PM
Yes it's an acme screw that moves the carriage- but it's a low duty cycle thing. The slotter would have the tool moving back and forth at many times the speed and far more often during the course of creating a slot or whatever. I think it will work ok- I personally wouldn't choose to do it that way.

I'm not sure what might be my choice of mechanism- probably a rack and pinion for a good length of stroke, and to keep the housing within a workable size. Your idea of the screw shaft would probably get you the smallest housing, and at the same time allow you to set up an optimum mounting arrangement. A large housing, as might be required for a crank type system, would be unwieldly if it's meant to be mounted on the carriage.

I'm curious as to what the stroke might be in your design-

One other thing- strictly as an idea- you aren't limited to the typical threaded shaft. You could use a section of ball-screw-

davidwdyer
01-11-2013, 05:44 AM
My slotter would probably see little use in practice.

I imagine about 3-4 inches of travel.

Ideally I'd like to take more of a cut that I could do with the one I made with a lever action.

Please excuse my ignorance, but what exactly is a ball-screw and how is it different from

what is on the lathe or mill?

darryl
01-11-2013, 06:41 AM
The lead screw you normally see is basically a piece of threaded rod, and whatever nut is propelled by it has a threaded hole to suit. A ball screw is basically a threaded rod, but the 'thread' is a semi-circular ball race. The nut is a mechanism which has the same race, but it doesn't engage the rod directly. Instead, a series of steel balls fills in the gap. There's a loop in the nut which carries the balls from one end to the other, so they don't escape. The balls roll and the nut moves along the rod. There's little friction, and it can be made so there's little to no play. These are commonly used on cnc machines where tight and accurate control of motion is desired.

Some have used them on manual machines- the main drawback besides cost is that they don't self-hold.

If you compare this to a ball bearing you'd see that the axial load capability is a function of the angle of the race and the number of balls in contact between the nut and the ball screw (not the only factors of course). As such it would be capable of large operating forces with low friction- just what you need. It's too bad they aren't made with a turn-around of some kind so you could simply spin the shaft in one direction and have the nut travel back and forth, like the line control on a fishing reel.

davidwdyer
01-11-2013, 08:20 AM
The lead screw on a lathe must take a lot of use and abuse along with (depending on your depth of cut) quite

a lot of force. How is it that something like this could not work for my application?

Abaker
01-11-2013, 11:26 AM
How about this: http://www.ebay.com/itm/Master-Lathe-Model-B-Broach-Broaching-Keyway-Cutter-/200875923281?pt=LH_DefaultDomain_0&hash=item2ec5235751

been scratching my head since it went up as to how to best go about attaching/holding/using...perhaps some pieces/parts are missing? The very basic movement of cutting edges I sort of think I get but how do you move it deeper under control...assuming I am correct in thinking it is some sort of rotary>>>reciprocating motion

This seems to be the traditional way motor driven inside slotters work - basically mini-shapers. This was before electronic motor controls. I suppose that a good sized acme leadscrew coupled to an electronically controlled motor and reversing/limit switches could get you the reciprocating motion you need. Not sure how much of an improvement this would be over the tried and true crank mechanism though.

BTW that ebay link is the slotting head to a Master Lathe Converter AKA a Versamill. It's missing the cover and really needs the base unit to work properly. I scored one of those recently and you can see a pic of the slotter (with the cover) lower middle of third pic down in this thread (http://bbs.homeshopmachinist.net/threads/57233-Sometimes-you-get-lucky).

darryl
01-11-2013, 07:47 PM
David, it's not that it won't work, because it will. It wouldn't be my choice of method, but that's no reason why you shouldn't do it that way. It sounds like a 'use what ya got' kind of thing, so all the power to ya.

mike4
01-11-2013, 08:04 PM
Have a look at the slotting attachement for a Bridgeport and work from there , they are fairly reliable and should be able to be made fit on your lathe with some size adjusment and the slot length is adjustable.
Even if sir Johns is a POS.

Michael

vpt
01-12-2013, 10:07 AM
I use a lathe headstock in the tool post of my lathe for special operations just like this.

http://img535.imageshack.us/img535/1456/gear002.jpg

http://img97.imageshack.us/img97/4499/gear001c.jpg

http://img62.imageshack.us/img62/9714/texas056.jpg

http://img18.imageshack.us/img18/7315/qctp018.jpg

davidwdyer
01-12-2013, 02:06 PM
That's interesting. What are you making there in the second picture?