powered cross feed on clarke cl430?

[mick70Participant @mick70]

as anyone done it?

or know of an article about it for any lathe?

used it on friends myford and would love to fit it on my clarke.

Edited By naughtyboy on 05/12/2016 15:29:16

[mick70Participant @mick70]

[MWParticipant @mw27036]

Hi Naughty boy,

I have thought about this in the past and as far as I can tell a motorized option would probably be the most straight forward route.

A mechanically operated version from via the leadscrew gear train would require, A. a means of separating the apron from the leadscrew such as using half nuts, and B. keywaying the entire length of the leadscrew so that the force of the leadscrew can be carried over onto a crossfeed gear train.( You need to separate them because otherwise the saddle will start moving at the same time as the crossfeed)

As I said option 2 is very difficult and would be hellish in it's own design terms, the only people who might have an easier time of it would be the people who were lucky enough to own the rare updated version of the CL430 known as the Warco WMT300/02 which has an apron and rack/pinion feed, (you don't necessarily need a rack and pinion as there is very little room to install this, and instead you could have a wormwheel feed on the handle but would still need the half nuts.)

That is about the gist of it for how most mechanically driven setups work, a plunger pushes a gear into engagement with a train that operates from revolving the keywayed leadscrew which the keyway is also holding a gear, which in turn is free to slide up and down the length of the bed and only engaged when you need it.

PS. It's very easy to criticize Clarke/ whoever in china designed this lathe, for not using an apron with rack/pinion arrangement in the first place but instead chose to permanently couple the leadscrew to the saddle, but it's also a lot to do with the surface finish of the work, it can operate in very fine movements and not twist so much from left to right as the saddle and tool progress into a cut, all it has to hold onto is a gib otherwise, and this is why most modern lathes have a polygonal profile bedway because the Vee shape alone doesn't hold onto the saddle very well without some additional form of support, like a guide rail, to keep the linear movement straight, that's why this conversion is about more than just decoupling a nut.

Michael W

Edited By Michael Walters on 05/12/2016 16:21:25

[mick70Participant @mick70]

will have to try and get parts diagram for the warco.

or the myford to give me some ideas.

Edited By naughtyboy on 05/12/2016 16:17:56

[MWParticipant @mw27036]

I wish you luck naughtyboy, I would help more if I could but I only ever got as far as making a prototype of a rack and pinion feed and found surface finish was my number one problem. I tried warco for help if they still did spare parts but they've since discontinued the lathe and can't help me.(If you want pictures and further details of this haveago project I can write it up in a post if you want, as I can set it up still).

Trouble is the only room for anything to sit on the bed is on the bottom, which meant turning the rack upside and having it roll along the base of the lathe. A wormwheel that rides along the leadscrew rather than a rack would be easier as you don't necessarily need to put a rack in place then.

I even advertised a while back in M.E.W for spares/scraps of a WMT300/02 but no one got back to me. It's bad enough trying to find people who own the normal warco branded version let alone the updated one!

Michael W

Edited By Michael Walters on 05/12/2016 16:27:13

[mick70Participant @mick70]

would appreciate if you could write it up please.

be a good starting point..

[MWParticipant @mw27036]

Fair dos naughtydog, i'll PM you tomorrow when I get it up. I'll start snapping pics and getting some material together. I will include what I propose what I think is the easiest way to get a decent outcome even if I haven't made that yet!

It will just gather up my findings into one place for anyone to either glare at or gaze upon!

Michael W

[mick70Participant @mick70]

thank you you're a gent.

[John HaineParticipant @johnhaine32865]

Why would you do anything other than an electric motor drive these days? See here for details :

**LINK**

[MWParticipant @mw27036]

Posted by John Haine on 05/12/2016 17:14:37:

Why would you do anything other than an electric motor drive these days? See here for details :

**LINK**

Hey John,

You are totally right for thinking it is the most straightforward way by a longshot.

Respectfully speaking, i'm sure N.D is aware that it can be done this way, but I suspect he relishes the challenge of trying to see how it would've been done years ago, it would also mean he could move the cross slide to create a specific pitch and moves synchronously with the chuck revolution. (before the subject of modern technology comes to swing back round at me, yes, it can be done with a stepper and encoder)!

(Infact it can just be a stepper alone, as there is a facility to have movement offset to speed up when it comes under cutting load, but this is controversial because people still haven't made their minds up over whether this can be termed truly accurate/repeatable in it's thread cutting performance. I suspect part size and material has a lot to do with it as the bigger you get the more the motor will slow under pressure.)

Michael W

Edited By Michael Walters on 05/12/2016 17:27:40

[mick70Participant @mick70]

i do like the idea of the challenge but happy looking at other ways of doing it.

[MWParticipant @mw27036]

 

Ok sorry I've been a bit late coming on here but man of my word here I am;

I have decided to keep my project of a rack and pinion operated saddle a separate post from this one so that I don't convolute it with two different questions (although they are inextricably linked together!) I found a diagram yonks back (like a number of months more like) that showed a simple crossfeed system on a myford. I'm not using the same computer as I did then so the images are lost unfortunately. But I am largely basing my design upon them.

Just thought i'd put this image up first that really underscores one of the big problems with making saddles/aprons;

That's just a view from the inside of a Colchester master I found on practical machinist. One of my favourite lathes actually but by no means the most complicated one out there, and yet were trying to achieve the same functions with a fraction of the space available. Its huge!

Here is my squiggle of the idea I formed about making a cross feed operated saddle, again, I don't touch on the issue of rack n pinion, and the whole thing assumes that's already done and you've got some half nuts, i'm sorry if it's a little hard to understand but i'm not on a commission for this drawing. If anyone has any questions i'll do my best to explain, and as you can see, these things are so crowded it was a little hard for me to fit it all in.

 

Ok so here it is, the trapezoid type objects to the right are the critical first step in this chain and they represent bevel gears, on the same shaft as the carrier, another gear sits behind the bevel gear which is an ordinary gear, the plunger is pulled in/out to complete or break the chain of force carried over onto the cross slide gear. They all need to be keywayed and grub screw hold down other than the leadscrew bevel gear which is free to slide up and down along the keywayed leadscrew, it is kept "tethered" to the saddle by (just one actually) metal bracket, you only need 1 because if we traverse back up the lathe bed it is just carried by the contact of the adjoining bevel gear.

So if you aren't all worn out after that i'll put a link to my failed racknpinion write up, which i'm obviously disappointed with but in light of recent questions, is perhaps worthwhile by the community.

Michael W

Edited By Michael Walters on 06/12/2016 18:39:48

[MWParticipant @mw27036]

Heres the Write up I made too; (Don't worry it's only taking you to a different post, not a cult secret nasty evil website)

**LINK**

Michael W

[Author]

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