Cole Chuck and Bandsaw Question

[James Baldwin]

Hi, Got a question about my Nova Cole chuck. I was using it to turn off the spigot and sand a small bowl and was wondering about the RPM. I think that the instructions said no more than 600 rpm. When I turned the spigot off I run the live center up against the bowl and run it about 800 rpm. Was this too fast? Another question kind of on the same subject. I was cutting rounds off the chunk of Elm that I was going to use (it's been curing for about 10 years) with my bandsaw (cross cutting) the blade was a 1/2" by 4 tpi, the round was about 8" in diameter anyway the blade went though in kind of an "S" pattern not straight up and down. Do I need to use a wider blade say a 3/4"? Thanks, Jim

[Steve Eure]

As for the cole jaws, I've turned with the tail stock at a higher speed, depending on the wood. Not all bowls are the same. You have to judge that for yourself. As for the 600 RPM stamp on the jaws, that's a guide line to go by. An out of balance piece of wood will fly off the lathe with them, so you need to be careful. I always use a tail stock until the very last where I can slow it down to around 300 or so.
As for the bandsaw blade, I would go with a 1/4" x 3 or 4 TPI. An 8" radius is probably too small for a 1/2" blade. I may be wrong on that, but I use a 1/4 for smaller blanks. I generally don't go over 3/8" for green wood, even on larger rounds.

[John Kananis]

1/2 inch blade should do fine with an 8" radius. However, you may want to consider 3 or 2.5 tpi. Which blade manufacturer? What type of bandsaw? How were you rounding it? Circle jig?

[Reed Gray]

No clue about cole jaws. With the bandsaw, I use a half inch Lennox bimetal Diemaster blade with 3 tpi, and have for years. No problem cutting circles down to 5 inch diameter. If the blade is cutting in an S shape vertically, my first thought would be that there is not enough tension on the blade. Second thought would be that the side of the blank that is on the table is not flat so it would rock while cutting the round. Third thought would be that you may have a dull blade. If you have to push at all, the blade is dull. If there are any burn marks on the sides of the blank, that indicated binding in the cut, and/or dull blade.

robo hippy

[John K Jordan]

James,

Nova recommends 600 RPM for safety. Many people run them faster with tailstock support. Unfortunately you'll know when it's to fast when the piece comes off and knocks you unconscious. But a piece can come off even at 600 rpm or lower, especially without the tailstock support. More chance if the bowl is larger and/or a bit unbalanced. Good face protection and use of the protective cage (if you have one with your lathe) might be wise. I personally quit using my Cole jaws some years ago, preferring different methods.

In my experience vertical bowing of a bandsaw blade in thick wood is nearly always due to insufficient tension, but can be aggravated by a dull blade, saw setup, and guide adjustment. What bandsaw? If you are using the tension indicator on the saw be advised that nearly all of them are inaccurate, some horribly so. Without a tension gauge some recommend setting the saw to the next higher indicator mark, i.e., for a 1/2" blade set it to the 3/4" mark. Far better is to use a tension gauge. I use a gauge each time I switch to a size and type of blade I haven't used before. I set the tension and note the position of the indicator needle (Rikon 18"), making a mark so I can return to the same tension without using the gauge. For example, with the 1/2" blade I use the tension indicator is between 3/4" and 1" on the Rikon. Tension gauges can be expensive but you can make one with either a dial indicator or some clamps and a digital caliper. There are messages here with pictures, instructions, and the math needed. If interested maybe someone can point to them or I could look them up when I get time. Also, if you belong to a turning club perhaps they would buy a tension gauge for shared use.

I use Lenox 1/2" x 3tpi or 4tpi for nearly all of my wood processing for turning, green or dry, up to 12" thick. I usually buy 8 or 10 blades at once and resharpen each several times.

JKJ


Hi, Got a question about my Nova Cole chuck. I was using it to turn off the spigot and sand a small bowl and was wondering about the RPM. I think that the instructions said no more than 600 rpm. When I turned the spigot off I run the live center up against the bowl and run it about 800 rpm. Was this too fast? Another question kind of on the same subject. I was cutting rounds off the chunk of Elm that I was going to use (it's been curing for about 10 years) with my bandsaw (cross cutting) the blade was a 1/2" by 4 tpi, the round was about 8" in diameter anyway the blade went though in kind of an "S" pattern not straight up and down. Do I need to use a wider blade say a 3/4"? Thanks, Jim

[James Baldwin]

Thanks for the information. My lathe does have a cage (Jet 1642EVS) which I do use for somethings. I failed to mention that I was cutting across the wood as a log. The bandsaw is a Grizzly G0555 with the riser installed. 13" capacity. I'll try increasing the tension on the blade next time. Jim

[Neil Strong]

If the blade is cutting in an S shape vertically, my first thought would be that there is not enough tension on the blade.

That is where I start with any bandsaw problems.

I increase the tension until I get a G out of the blade when plucked.

[Reed Gray]

If you are cross cutting a log as in cutting rounds off the end, then you need a V sled to keep it from rolling into the cut, which can cause all sorts of problems. Not using one could also result in the piece rocking, which can add to blade woes.

robo hippy

[James Baldwin]

Thanks, Looks like I'll be building one. Jim

[John K Jordan]

Thanks, Looks like I'll be building one. Jim

Reed is right, crosscutting a round without some means of restraint is a potential disasater! In a millisecond the cut can become uncontrolled, ruin the piece, the blade, maybe damage the bandsaw, and worse, the hands. I haven't built a sled for log-sized rounds, although I did make a wooden v-block to cut smaller rounds safely.

Instead, I use wedges. When cutting round and round-ish blanks from square stock I save the offcuts to use as wedges for stabilizing a variety of cuts on the bandsaw. If I don't have some that fit the log (sometimes more important for larger diameters) I'll simply cut some wedges from scrap with an approximate suitable radius. I usually use two wedges in the front and two in the back.

But most of the time I don't crosscut log sections, but process wood into flat blanks of suitable thickness, air dry, then cut those into bowl, spindle, or other blanks as needed. If I need to make cross cuts, I generally use a tool designed for this - the chainsaw! (I keep a corded electric Stihl saw for use just outside the shop door.)

JKJ

[James Baldwin]

John, I watched your video and found it pretty informative. I see where I made mistakes. I'll be clamping up the logs in my wood splitter and cutting them with one of my chainsaws. Let's for and 8" log I could use my 5 cu in with the 36" bar. Just kidding. I have smaller saws and shorter bars. I also can cut them with a SawzAll. Jim

[Brian Deakin]

What can be a problem with Cole jaws is if you run them at a very fast speed and then turn the speed off abruptly the momentum and weight of the Cole jaws plus bowl can cause the Cole jaws to unscrew from the headstock

To minimize this problem I gradually reduce the speed to zero and as the spinning bowl slows place my hand on the base of the bowl as added support and slow the bowl further
I am not sure but some Cole jaws may have grub screws to eliminate this problem

[Neil Strong]

What can be a problem with Cole jaws is if you run them at a very fast speed and then turn the speed off abruptly the momentum and weight of the Cole jaws plus bowl can cause the Cole jaws to unscrew from the headstock


This was always a problem with turning larger platters outboard before we had dynamic speed controls. Adding a thin rubber washer between the back of the faceplate/chuck and headstock spindle shoulder reduced the risk of that happening.

I expect that the recommended speed limit with Cole style jaws has more to do with their limited workpiece holding ability.

[Randy Heinemann]

I've used these Cole Jaws since shortly after I began turning a few years ago, but quickly learned that one of the big determinants of whether they are good for turning off tenons is the shape of the bowl. They hold much better for bowls with bowl lips with and outward curve regardless of the shape of the bumpers used. I don't use them much anymore because I have found other ways to hold the bowls when turning the tenon off. One way is the Rubber Chucky. Another way (which I learned about but haven't done yet) is to turn an appropriate size drum and use craft foam on the edge to hold it. Either of those methods require more than one size to accommodate different diameter bowls. I also own a Longworth Chuck with Doughnut rings from Ron Brown's site. That works well but was pricey and isn't necessarily the easiest setup for a relatively short task. Were I to do it over again I wouldn't spend money on all these things and go the route of turning the drums with foam. There are other ways also. The Cole Jaws work best with small bowls rather than bowls near its capacity.

[Neil Strong]

I should add that for bowls you don't need to have a spigot on the bottom that has to be turned off...

I mount the rim side of the blank to the chuck to turn the outside of the bowl and to finish the outside in one go.

I then mount the bowl with dovetail jaws into the nicely formed foot recess to turn the inside and then apply a finish.

Remove from lathe.

Job done.

I like a nicely done foot on my bowls... with the right proportions to the shape and diameter of the bowl.

The downside of this method is that I have to have many jaw sets (mounted on their own chucks, of course :~) to get the full range of foot sizes for the different sized bowls.

I have produced more than a thousand bowls with this method.

I do have a set of Cole jaws but only use them occasionally, primarily for holding multi-axis turning.

What do I think of bowls that have their feet completely turned off... a lazy effort and more often than not thugly!

The obsession for removing all evidence for how a bowl was held during its making goes back to when we only had faceplates that did leave unsightly rough screw holes in their bottoms. Somehow that obsession has persisted into the era of the modern chuck. Time to move on and to delight the buyers and users of our bowls when they turn them upside down. That is the first thing I do when I pick up a bowl made by another maker and I am invariably disappointed if all I find is a shallow concave 'footing' with nothing to say other than... nothing to see here!

[John Kananis]

Neil, how deep of a recess do you work with? (I'm assuming you leave the entire recess intact - unless I misread)

[Neil Strong]

Neil, how deep of a recess do you work with? (I'm assuming you leave the entire recess intact - unless I misread)

About 3/32"/2mm on smaller pieces up to 8" diameter and progressively deeper, up to 3/8"/5mm, on the largest diameter platters and bowls. You don't need a very deep recess if you have genuine dovetail jaws (without a small chamfer on the edge) and, of course, turn without getting catches... :~}

I sometimes go deeper on some pieces, not so much for the mechanics of holding the piece but if I think the visual design needs it.

The thickness of the foot also needs to be proportional to the diameter of the piece, not only for aesthetic purposes but also to ensure that there is enough wood there to hold the outward thrust of the dovetail jaws. This will very a bit depending on the wood.

Only the jaw bearing area (which will vary with the jaws you are using) needs to be flat inside the foot, so proportionally quite a narrow ring. The remainder of the recess area is design territory that can be simple or elaborate as you wish (beading, chattering, knurling, carving, gold leaf, etc) as long as it doesn't protrude out further than the foot.

I tend to follow the curve of the inside of the bowl, so that the thickness of the bowl follows all the way through. This results in a small slightly domed and decorated area where I put my mark. But, you would mostly know from the design that I was the turner by just looking at the foot without my mark.

The foot is one other area where you can apply your individual design style and turning skills.

[John Kananis]

Very cool, thank you for your detailed answer.