Could someone explain the 6000 rule and 9000 rule? Thanks in advance.
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Teknatool chucks not suitable to woodturning.
- Thread starter Lennart Delin
- Start date
Any chance you could share where you purchased that chart? That would be quite handy to have...
Well let me finish by saying that it is not the size of the jaws that governs the suitable turning speed. I came to think about an article on chucking I wrote 25 years ago. The article is about different kinds of jaws etc, but not once did I take up turning speed. There are so many different factors that affect the suitable turning speed, so I think any attempt to give a rule is meaningless. The only rule is "You should feel comfortable". Here is my article originally published in Woodturning 2001, a little updated. Remember at 2001 the present 4-jaw woodturning chucks were quite new.
Maybe just maybe a therapist might help you get your question answered as you seem to want us to dislike Nova/Teknatool really bad. What Russell says above may be true for most that I may have looked at the speed guide once (or not) but I have never looked at the paperwork in any of the chucks (regardless of brand) since looking at the paperwork on my first chuck roughly 24 years ago. Maybe I was lucky to have mentor who helped me through those first years.
There is a world of difference between a commercial turner and a hobby turner, it is virtually like night and day.Yeah, I heard about the guidelines when I started as well. Granted, that was only five years ago...
Regarding "speed"...I think that is exactly what Batty gets to in his video (I'll find the link)...RPM is technically not speed!Thats' where the "road speed" comes into play, which would be the rotational velocity of the surface of the blank. A 6" bowl would require a higher RPM, for its surface to move the same speed as a 16" blank at a lower RPM. I think that's why Kent Weakly frequently discusses the "feel" of the speed of the blank, and IIRC his lathe's RPM readout is broken (or maybe he manually disconnected it), because he prefers to dial in the feel of the right speed, rather than be concerned with RPM.
I also don't know enough about the ~1000rpm "drop vs. fly" cutoff...I am not sure if that is purely an RPM thing, and at that RPM a blank of ANY size would fly? Or if it depends on the radius of the blank... In any case, I tend to turn at around 1200rpm for bowls or platters in the range of 10-14" (I don't have many much larger than that, TBPH).
Something else, too...I used to have a Laguna lathe. I was quite enamored with their PWM technology at first, however...in practice, the nature of their PWM drive left me feeling LESS SAFE at any RPM, than any other lathe I've used. The Powermatic uses a VFD, and while a VFD internally relies on a PWM as well, the actual output signal is smoothed into a more natural sine wave. My experience has been, I feel FAR more comfortable and safer turning at 1200-1300rpm or so, with a 10-14" blank, than I ever did turning anything on the Laguna even at 900-1000. The PWM on the laguna had no smoothing, so the stepped nature of the PWM was directly applied to the spindle and thus the blank. When you touched the tool to the wood, that changes the load, and the RPM would adjust. With the Laguna, you would feel a sudden slowdown, then a rampup in speed, then a small ramp down in speed, as the lathe adjusted its PWM to try and update the power to continue delivering the same RPM. With the Powermatic, I've NEVER felt that same kind of jolting RPM change. I can momentarily hear a change in the motor, but the response is far more natural and I have never had any issues turning at higher RPM. The Laguna, I eventually just stopped turning bigger items on it...just never "felt" safe given its unnatural response to changing load.
Anecdotal, I know...but, I wonder, if maybe that might play into who considers what speeds to be safe and reliable?
Any manufacturer must have their lawyers on speed dial. It is a part of doing business. Theirs or any other chuck can handle any lathe speed. It’s ability to secure any piece of wood under any circumstance that is the issue. A lot of turners have been killed or severely injured from this very real limitation. Every turner that has any experience at all has seen or experienced a piece of wood flying off of a chuck. It is our responsibility as teachers to educate newcomers as to the possibility of a sudden death experience when using a lathe, chuck or not. It is the responsibility of a manufacturer to do the same in a legal pugilist way to keep from losing their business. This is reality.
Jer
Jer
I have never seen anything like that from other suppliers, not saying I checked all manufacturers. Axminster Evolution i.e. have nothing of that rubbish. Their cautioning is quite good:
Safety instructions for chucks
When using this chuck please follow these basic safety precautions:
DO ensure the chuck is screwed fully onto the headstock shaft.
DO ensure that all accessory fittings are secure before starting your lathe.
DO start the machine in a slow speed if the work is unbalanced.
DO make sure the chuck key is removed from the chuck before switching on.
DO be aware that when gripping large diameter workpieces that the jaws may extend beyond the boundary of the chuck body.
DO keep your hands clear until the chuck has stopped rotating.
DO NOT attempt to exceed the normal capacity of any jaw fitted to the chuck as the jaws may not fully engage the scroll if they are extended too far.
DO NOT run your lathe in reverse, unless you have purchased the Reverse Locking Chuck.
Can't remember who said it, but some thing like "it is easier to get clean smooth cuts at higher speeds". To that, I would add, yes, and it makes your catches/mistakes much more dramatic. My first 3 lathes didn't have rpm indicators on them, so I learned to turn by what felt right. I still never look at my rpm indicators as I turn now. It is a question that always gets asked in videos now days, and I have to stop and look, some thing I am not used to. My Beauty was one of the first, with 3 speed ranges. I kept it in mid range, and had the speed limits "adjusted" with the help of Brent. The mid range, which is where it spends most of its time has a max speed of 2200 rpm, according to Brent. I did some times max that speed out when turning smaller bowls. Not often though.
robo hippy
robo hippy
Consider the “road speed” of 1/2” spindle spinning at 3000 rpm. If it breaks of somehow comes off the lathe it will just fall and won’t bounce and travel and if it did the mass is not dangerous.
One thing experienced turners don’t have is poor tool control that invites catches. Compare to the guy I once watched pry the same bowl off the lathe multiple times.
(OOPS: wrote this yesterday and forgot to click the “Post” button. I didn’t read everything to see if someone already said the same thing.)
Each manufacturer handles the issue in their own way. It is usually the “standard practices “ approach. I was not justifying their legalese baloney which makes no sense whatsoever as it suggests the chuck itself is faulty. just pointing out that the issue exists for everyone.
It's hard for me to understand why you're belaboring this issue. If you feel uncomfortable about buying new or using already owned Nova chucks/jaw sets, don't do it. Those of us who own and used Nova chucks and jaws have no problem with them. Are there better chucks/jaws available? Probably, but Nova's are fine and they work well. I've never had a piece fly off if the tenon and bottom face of the piece are cut correctly, regardless of the speed. I would have loved it if I had started out with Vicmarc's chucks but I didn't and, to spend hundreds (maybe close to $1,000) on replacing all my chucks and jaws is nuts when the Nova equipment works as well as it does.
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I have only read good comments on Teknatool´s chucks. I was therefore very surprised when I read their, in my opinion, idiotic recommendatons on rpm based only on jaw sizes in the manual, that would make them unsuitable for woodturning. I asked for your comments on this. That was all.
I will not comment further in this thread.
I will not comment further in this thread.
I made it in excel. Upon reviewing it, I had some nomenclature wrong. I don't remember the source material for the "low speed 9 mph" line. The "Roughing 18 mph" is the 6000 rule, the "Finishing 27 mph" line is the 9000 rule, and the last is Batty's 40 mph line.
Obviously when starting with an out of balance blank, lathe movement controls the speed. Once somewhat balanced, the chart provides me with a target value, which I then may adjust per the situation. I tend to turn near the 27 mph line for roughing or finishing if vibration and wood allow it.
Anyway, here is a jpeg of the chart that should be downloadable.
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@Doug Freeman Nice graph. It is one of the few better things that has come from this thread. I did own 7 Novas and 2 Record Power chucks. I switched to the Axminster chucks because I liked their jaw change method. Not because the Nova/Record chucks didn’t work or I could turn at a higher speed. They worked fine, I was just buying chucks so I didn’t have to mess with the screws to change jaws. Nine chucks is way too many (for me) and storage was becoming an issue. Technatool makes good products and if they posted a chart like yours we wouldn’t have this thread. I still believe those speeds they posted are ONLY when the maximum diameter is being turned and not a limit for every size turning. Technatool is at fault for not being clear about that chart.
Thanks! That will be handy.
Regarding the starting out and "lathe movement" comment...what do you mean by lathe movement? As in rocking or something? Since getting the Powermatic, I haven't really had a problem with that as it is extremely heavy and stable, and I've still generally rounded my blanks around 1000 rpm. I haven't really turned anything bigger than about 15" maybe 16" on it yet though, and thus far I've also always used either a woodworm or faceplate, which I guess would add some stability. Maybe if I'm doing my initial rounding and shaping between centers, it might be more critical to watch the speed...
FWIW, when I first started turning, I was basically following the blue Low Speed line. I honestly found it so hard to turn anything with the speed that low. The slow "chunk chunk chunk" of the tool on the wood made it hard to keep the tool at a consistent depth, seemed to cause much worse tearout, etc. Even for a 10-14" platter blank, the roughing speed (green line) also always felt too slow and I had so many problems getting good results.
I think that is why I latched onto the higher speed turning when I first started watching Clewes and Batty do their thing. I mean, clewes, that guy will turn a 12, 14, 15" platter at 1250 or so. Through and through, from initial shaping to finishing sheer cuts and all. When I started doing that, it was so much easier to get clean cuts, with minimal to no tearout, from the get go. Shortens the time to turn as well. Obviously tool sharpness matters still, and with poor sharpness tearout is still a problem even at the higher speeds, but...I dunno, it just seems easier to get good results at higher RPM. Batty's 40mph seems to be pretty much on the money there...
How do the Axminster chuck jaws change out? I've heard of Axminster, haven't looked into their chucks. With all of my Nova and RP's, I hate changing the jaws. Its eight little black screws, and I've had to buy replacement screw sets several times now, because they just LOVE to hop out of my hands into the dust pile!
I was looking at Easy Wood Tool's chucks for their quick change capability...but, their chucks and jaws are rather expensive. I do like having a few chucks at a time, and sometimes even a couple sets of the same jaws, so I can chuck something up, leave it chucked, and switch to another piece with a whole different chuck and jaws. I can keep several projects going at once that way, even through finish drying periods and the like.
It would be nice to have quick-change jaws though...man, I'm so tired of losing chuck screws.
With the Axminster you buy the jaw slides and jaws. It is an added cost. Axminster the added one screw to prevent over extending the jaws that needs to be removed. it is on the bottom and is a cap head screw. Then you just crank out the jaws and slides and crank in the new jaws and slides and reinstall the screw, less than a minute. The jaw slides were just over $30 when I bought them and now are over $50. Every time I bought Nova jaws I was buying a new chuck body. So even buying jaw slides it is still cheaper. I also bought the O’Donnell jaws that I use a lot. Other features are stainless steel body. I intended to have only two Axminster chuck (and my Hurricane 125), but Lee Valley was closing out the Axminster brand and I bought another SK100 and Sk114 and some addition jaws and slides at a very reduced price. I also have the Axminster eccentric chuck that is used with their C jaws. I do like the Axminster features/jaws that Nova doesn’t have.