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gixi Sun 24 January 2010 09:56

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Hi Kobus ! Very inspiring the way you build the indexer. After a few days of searching with local vendors I found something that could be use as an indexer.
But every wood lathe doesn’t have that jaw chuck. Is it OK if I use it as it is ?
Marius

Kobus_Joubert Sun 24 January 2010 11:08

Hi Marius, Things to check before you buy.

I think you should be able to get a 4 jaw chuck that will screw into the shaft for that machine. This juck is used to screw the piece of wood from behind.
Take the tailstock and see if it moves if you rock it. Must be rock solid.
Line up the tailstock live centre point with the headstock...see if that are at the same height...also not skew.
See if you can change the shaft to make it longer to add the stepper gear.
Also make sure that there is enough solid material to attach the bracket that you will hang your stepper onto.
Just buy a small metal lathe at modify the thing to accept a stepper....they are usually more rigid and precise...then you can turn metal with CNC as well.

Good luck.

gixi Sun 24 January 2010 11:24

Hmmm... I was afraid that you'll recommend 4 jaw chuck :D. My common sense tell me to use 4 jaw chuck but I was afraid not to be very heavy but again you are right, the entire construction should be very sturdy and rock solid. I'll do my homework this time more carefully. Thanks !
Marius.

hennie Sun 24 January 2010 11:48

Marius I have one of those that looks the same wich I bought about 3 years ago.It came with a copy attachment.I used it to turn four legs only and then it went to collect dust.I will be using it to do my MM lathe.I dont see anything wrong with it and it is a good starting point.Yes you will need to modify it a bit but hey anything is possable.(will post pic tomorrow)

javeria Sun 24 January 2010 12:33

I got mine
 
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these are the alu gears I got.

gixi Sun 24 January 2010 13:04

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Hennie tomorrow I'll go to see some lathe models. This one catches my eye because of the price (100 Euro) and it's new. But I have to see if it's OK to make the proper modifications. Meanwhile searching the German EBay I found some useful things...
That lathe with extra 4 jaw chuck its 450 Euro, witch is a good price (I think...).
Regarding the necessary modifications: after I finish the MM now everything looks easy to build or modify :cool:.

Kobus_Joubert Sun 24 January 2010 22:11

I wish my 4 claw chuck looked like the one in the green picture...much easier to tighten than the one on the right like mine.

Gerald D Sun 24 January 2010 23:27

That "self-centering" 4-jaw chuck only works if your stock is square - it is a real curse when the stuff is off square and you did not realise it.

Jan de Ruyter Sun 24 January 2010 23:51

A wood lathe usually comes with a live centre for the headstock. (Like the Einhell.) This will be used to make a live centre to drive the work piece. No need for an expensive chuck.

A faceplate is also very useful to clamp stuff to the headstock. Just screw it to the faceplate from the back. You can even make clamps on the faceplate to function like a 4-jaw chuck so you can clamp square and off-centre items. With wood you don't look at 20um tolerance, so centering on the centre is less of an issue than with metal.

A problem with any lathe is the alignment of the centres. If this is not accurate, you will end up with a tapered item. Bolt the lathe down to a sturdy frame using jack screws (a simple 12mm MF HT bolt with three nuts will do) to line up the centres properly. On a metal lathe, use an engineer's level (not the one you buy in the hardware store) but with the wood lathe it is better to just turn a test piece.

Gerald D Mon 25 January 2010 00:04

Jan, the "expensive" chuck is needed for true indexing work where you could be changing direction, or need to hold a position firmly while the other axes do their thing. A "spur driver" is okay for lathe type turning work, but will develop backlash for indexing work.

Kobus_Joubert Mon 25 January 2010 01:58

Gerald you take the word right out of my mouth.

Jan for indexing you NEED an expensive chuck, not just a little claw thing that works in one direction.

The self-centring is what I need for my indexing as I will start with a perfect square blank as the top part that fits onto the rest of the table skirt etc.

Gerald D Mon 25 January 2010 02:55

Centering with individual jaws is not too difficult. I use a digital vernier to measure the jaw positions relative to the OD of the chuck after the first tightening, calculate the average (center), back out the two jaws that are too deep, tighten the other two.

gixi Mon 25 January 2010 07:55

In most of the situations it's better to use a perfect square blank or a rounded one. So the "expensive" option for a chuck is the best. On the other hand let's don't forget the time that could be saved with a self centering system.

J.R. Hatcher Tue 26 January 2010 06:04

What does a self centering system look like???

KenC Tue 26 January 2010 06:35

a 3-jaw chuck?

J.R. Hatcher Tue 26 January 2010 06:37

I must need another cup of coffee to have missed that:D thanks Ken

KenC Tue 26 January 2010 06:41

You are welcome J.R., maybe you should try some strong Chinese Tea. :)

Kobus_Joubert Tue 26 January 2010 09:21

The 3 jaw is no good for my application. Most of my pieces will be squared at the top.

You do get self centering 4 way jaws.

http://www.allproducts.com/manufactu.../product3.html

Gerald D Tue 26 January 2010 10:22

If the keyhole is between the jaws, then it is a self-centering "scroll" type. If the keyholes are directly behind each jaw, then only that jaw is moved by the key.

KenC Tue 26 January 2010 21:13

But over time, without much care, self centering chucks do wears off & loose the center...

Kobus_Joubert Wed 27 January 2010 13:04

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Anybody out there that can help me please feel free to do so. As I am not very good with CAD programs and visualizing 3d stuff I am batteling a bit over here.

I have loads of DXF fils with nice turned legs, but how to MAKE THEM FLAT is another story. These gadgets in V-Carve Pro takes a flat design and wrap it around either the X or Y Axis.

So somehow I need to get this DXF file spread open and do my cutting paths from there.

Something like this

Attachment 8298

From a tutorial on the gadgets, this picture is what it should do, but how do I do the 2D from the DXF file

Attachment 8297

Attachment 8299

Gerald D Wed 27 January 2010 20:32

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Is this what you are looking for?

Attachment 8300

Castone Wed 27 January 2010 20:44

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In my software for a wrap I draw my length then I take my Dia time 3.1415 using the largest one to get my width , the smaller will lap over and blend. Then from a side view or end view extrude the profile you want. Your software may also be able to run a solid moldel . I can send you this file in an STL if you would like. If you draw your own design you would just use the flat layout and cut or raise profiles to make a design .

Kobus_Joubert Wed 27 January 2010 22:10

Thank's Leo. Will look at this in more detail tonight.
But in the meantime during my sleep last night I thought of the following. With the indexer / flat / wrapping turning a thing like this will take some time.
Because I have the electric motor on, I can spin my wood at a constant speed.
All I need is to tell Mach3 to move in the Y-Direction and as it moves, it must plunge the Z-Axis to create those shapes.

Any idea how to draw the picture to do this?

Thank's Gerald, that is the same as in my first picture, but I don't know how to translate this to Z-Movement...will have to figure this out.

Castone Wed 27 January 2010 23:18

Kobus since you do have a regular motor also , you could turn this. You should by able to change to a side view then draw the profile, you would then select this line as a contour to cut, You can check your G code to see if it out puts the right way with Y and Z only, You will have to play with your feed as and end mill will not remove the material as fast as a lathe tool will .I would start with a very slow feed and work my way up , a feed for a lathe would be around .008" per rev of coarse that is for cutting steel,so be careful if you try this. If your software can transform tool planes you could draw it from the top view and then tranform it to Z or rotate to the proper plane. You would be using the software like it was a CNC lathe to profile the part. It would be fast for cutting profiles, then you could come back with the indexer and add flutes or other designs. We have a lathe at work with live tooling and a C & Y axis that we use like this.

Castone Thu 28 January 2010 00:15

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See if you can open this. If you can go to a side or end view and see if you can edit the profile , If you can this will be the view you will need to work in , to draw a Z profile.From the top it should look like a straight line.

Castone Thu 28 January 2010 00:16

You may need to scale it up some.

Kobus_Joubert Thu 28 January 2010 01:01

Thanks Leo, What I will try tonight.

Draw the profile leg as Gerald also gave me, but without the line at the back....only the profile part.

Lay out the part so that the Y-axis will go North - South.
and the profile on the X-Axis...East West.

Then go to Mach3 and re-configure the pins and ports so that the X-Axis signals are outputted to my Z-Axis

Now The Z-axis should use that profile that was on the X-Axis to plunge the router up and down to create the profile and the Y-axis wil take it up and down the piece of wood.

Nothing to loose ALL to gain.

Castone Thu 28 January 2010 06:51

Kobus, you should be able to do it with just the y and Z .CNC Lathes use X and Z . What would help some ,is if you could find some free lathe software that had a cad package with it , to draw your profiles in.

Gerald D Thu 28 January 2010 06:56

Kobus, realise that your cutter's tip is going to be expected to work some miracles; sharp left AND right corners, plus convex and concave surfaces. A square tipped cutter following that profile is going to supply some surprises.


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