How to turn OD from square, no hole in blank?

[mikeschn]

So I have a question about drive centers for my lathe...

If I drill a hole all the way thru my square blank I can use a mandrel on a #2MT.

If I drill a hole part of the way thru my square blank (closed end) I can use a blind mandrel #2MT.

If I have no hole in my square blank, but want to turn the OD so that it fits into a Beall collet, would I use a drive center #2MT?

Mike...

 

[Rink]

use a self centering 4 jaw chuck?

 

[duncsuss]

If I have no hole in my square blank, but want to turn the OD so that it fits into a Beall collet, would I use a drive center #2MT?

Do you have a 4-jaw chuck? If so, that and a live-center at the tailstock will let you turn one end round, then you can flip it and put the round end in your collet chuck. (If you don't have jaws small enough to grip the blank, remove the jaws and use the hole in the middle of the slides -- you don't need a strong grip, just enough to turn the blank.)

If you don't have a 4-jaw chuck, you can use some kind of drive spur in the headstock and a live-center in the tailstock. The type of drive spur isn't really important -- regular 4-way, 2-prong, cup, Stebb, 60 degree dead-center, whatever.

It usually helps the live-center if you use a center-drill to create a small 60-degree dimple in the end. (Same at the headstock end if you are using a conical dead-center to drive it.)

 

[mikeschn]

No, I don't have a 4 jaw chuck. Is that the preferred method? Better than a drive center?

Would something like the Barracuda Mini CSC500K work?

Mike...

 

[SteveG]

If I want to turn an undrilled square blank on the wood lathe, I will mark the center point (or mark a point that will become the desired center point). Put a dimple at the marks, then mount between centers, a step drive center and live center in TS, and turn to desired diameter. This procedure does not need to be remounted to turn entire blank, and yields a cylinder shape with center points established.

 

[duncsuss]

No, I don't have a 4 jaw chuck. Is that the preferred method? Better than a drive center?

Would something like the Barracuda Mini CSC500K work?

Mike...

It would work -- whether it's "the preferred method" depends on who you ask!

I normally use a dead center that Rick Herrell made for me from a piece of 1/2" diameter stainless steel -- he shaped one end to a 60 degree cone. Using that, I can leave my collet chuck mounted the whole time and not have to take chucks on and off.

I spot-drill the ends of blanks with a 60 degree center bit so the dead center has more surface area in contact with the blank when it's driving.

 

[mredburn]

Its also possible using a 3 jaw chuck. You sand or grind one of the corners flat to make a short notch. That notch sits on one of the jaws and the other two grab at the sides of the blank. (left Picture)
Its easier if the blank is oversized but it can still work. In the right side picture I have a 3/4 square blank with a 3/4 round shown in red and a triangle drawn on the end shot. YOu can see the jaws would be able to grab the blank to round it.

 

[mikeschn]

I normally use a dead center that Rick Herrell made for me from a piece of 1/2" diameter stainless steel -- he shaped one end to a 60 degree cone. Using that, I can leave my collet chuck mounted the whole time and not have to take chucks on and off.

That's actually an awesome idea! Is Rick Herrell the only person you can get that from?

Mike...

 

[Charlie_W]

Here are a few #2 mt drive centers.
I use the ring center(safety center) on the right for much of my smaller spindle turning.

Remember, all you need to turn is just part of your blank so you can get it secured in your collet chuck. Then you can finish rounding.
I still use tailstock support as much as possible.

 

[duncsuss]

I normally use a dead center that Rick Herrell made for me from a piece of 1/2" diameter stainless steel -- he shaped one end to a 60 degree cone. Using that, I can leave my collet chuck mounted the whole time and not have to take chucks on and off.

That's actually an awesome idea! Is Rick Herrell the only person you can get that from?

Mike...

I doubt it -- but he's an IAP sponsor and does great work at a very reasonable price. (I have several of his pin-chucks for my kitless/closed-end pen work, his off-set sanding jig, and at least one tool rest he made.)

 

[Charlie_W]

I normally use a dead center that Rick Herrell made for me from a piece of 1/2" diameter stainless steel -- he shaped one end to a 60 degree cone. Using that, I can leave my collet chuck mounted the whole time and not have to take chucks on and off.

That's actually an awesome idea! Is Rick Herrell the only person you can get that from?

Mike...

I doubt it -- but he's an IAP sponsor and does great work at a very reasonable price. (I have several of his pin-chucks for my kitless/closed-end pen work, his off-set sanding jig, and at least one tool rest he made.)

Rick's tool rests are a blessing to turners! Fantastic machining and finishing!

........Now, back to the thread subject!

 

[duncsuss]

Link to Rick's listing in the vendor area (it takes me a while to find it :biggrin

... CLICK HERE

His "straight shank dead center" is all the way at the end (but I always see something else I'd like to get as I'm scrolling down!)

 

[mikeschn]

So lets assume that I am using a dead center in a collet, and a live center in the tailstock.

How important is it that the 60° center drills are exactly in the center of the piece? I would be using a drill press to do the 60° holes, and it may not be THAT precise...

Mike...

 

[Charlie_W]

So lets assume that I am using a dead center in a collet, and a live center in the tailstock.

How important is it that the 60° center drills are exactly in the center of the piece? I would be using a drill press to do the 60° holes, and it may not be THAT precise...

Mike...

As long as you can get the finished turned round stock you want, exact center is not critical.

 

[bmachin]

I must be getting old. Back in the bad old days, there were spur centers and faceplates to drive the work so the question would never have been asked. A lucky few had adapted machinist's 3 jaw chuck to their wood lathes. Of course the jaws protruded and more than a few knuckles were skinned, bruised, and probably broken.

Don't think I want to go back.

Bill

 

[Sylvanite]

I use a PSI safety center (like a spur center, but it will slip if you get a catch) and a live center. You can see a picture at http://www.penturners.org/forum/f30/using-skew-121862-post1701297/#post1701297.

 

[farmer]

No hole needed

So I have a question about drive centers for my lathe...

If I drill a hole all the way thru my square blank I can use a mandrel on a #2MT.

If I drill a hole part of the way thru my square blank (closed end) I can use a blind mandrel #2MT.

If I have no hole in my square blank, but want to turn the OD so that it fits into a Beall collet, would I use a drive center #2MT?

Mike...

Actually you don't even need to put allot of force to turn the wood with a dead center and not even use spurs.
Hot knife through butter nice cuts no blow outs. you can turn the lathe by hand the cut is that effortless .


Live cutting rules ......

 

[More4dan]

Fortunately I have a metal lathe and I made a dead center out of a 1/2" diameter steel rod. I just turned a 60 deg point on it and I put in my chuck but a collet would work. It also works for turning between centers. I also just center drill each end of my blank and mount between centers and turn round. I can then use my 3 jaw chuck to hold the blank while drilling. Now my blank and the hole are aligned. Squaring is easy once I glue in the tube, I set up a fence square to my belt sander and sand to the tube. ID and OD are parallel so the face is square.

The blank will occasional stall if I'm taking too great of a cut. I either back off a bit or clamp it tighter. I've even used this method for turning metal between centers and it works w/o using a dog to clamp the material to the drive end.

Danny

 

[Bill in Buena Park]

So I have a question about drive centers for my lathe...

If I drill a hole all the way thru my square blank I can use a mandrel on a #2MT.

If I drill a hole part of the way thru my square blank (closed end) I can use a blind mandrel #2MT.

If I have no hole in my square blank, but want to turn the OD so that it fits into a Beall collet, would I use a drive center #2MT?

Mike...

Hi Mike,
To clarify - isn't this just normal spindle-turning you're talking about? Like making a tool handle? If so, why not keep it simple - mark your center on both ends of the spindle, drive center (your choice) in the headstock, and live center in the tailstock. Turn your tenon/spigot at the live center end, then reverse the piece and chuck into your collet chuck.

 

[mikeschn]

Bill,

No spindles here... this is for getting the right tools to do kitless pens. Now I suppose if I found a drive center with a 1/2" shaft instead of a MT, that might work, but will it work on acrylic and polyester?

Mike...

Hi Mike,
To clarify - isn't this just normal spindle-turning you're talking about? Like making a tool handle? If so, why not keep it simple - mark your center on both ends of the spindle, drive center (your choice) in the headstock, and live center in the tailstock. Turn your tenon/spigot at the live center end, then reverse the piece and chuck into your collet chuck.

 

[Skie_M]

Uhh ... even after I got my 4-jaw chuck, I still just round my blanks between centers without drilling holes through them before I measure for length and cut them off and then drill my holes using a 3-jaw chuck and a MT1 drill chuck in the tailstock. It's simple and it works.

Now, in your case, you want to make something for a closed end turning, yes? Same steps, just measure your DRILL BIT and mark where you want for the depth of your hole so that you don't go all the way through. Also, make your blank extra long so you have some wiggle room for gripping the blank while working on it and using your tailstock to apply a steadying force to make your turning go easier ... once your major shaping is done, turn off the end of the blank and get to sanding and finishing!


Any woodworking tools and woodworking techniques should work just fine on acrylics and plastics, given the proper tooling, working speeds, and patience. Just keep in mind that some types of solvents may melt certain acrylics and other things ...

 

[Bill in Buena Park]

Bill,

No spindles here... this is for getting the right tools to do kitless pens. Now I suppose if I found a drive center with a 1/2" shaft instead of a MT, that might work, but will it work on acrylic and polyester?

Mike...

Thanks Mike - I erroneously assumed "wood" and not other materials. But I believe the principle is the same - after all, a pen is basically a hollow spindle. If you can accommodate the points of drive and live centers, you should be able to spin your blank and turn any portion thereof to round. But personally, if I had to do this, a pen-jaws chuck would be worth the investment.

 

[anthonyd]

Hi Mike,
I use a 1/2 inch MT2 Sorby Stebcenter in the headstock end and a 60 degree live center in the tailstock end. I turn the blank between centres on my metal lathe. This will probably work on a wood lathe too.

Tony

 

[mikeschn]

That looks like another good option!

Mike...

Hi Mike,
I use a 1/2 inch MT2 Sorby Stebcenter in the headstock end and a 60 degree live center in the tailstock end. I turn the blank between centres on my metal lathe. This will probably work on a wood lathe too.

Tony