New lathe: dangerous low turning speed?
Well here I am, I just purchased a 2 HP Grizzly lathe (back ordered)with 10 speeds – the lowest being 500rpm.
In another feed, I got a reply that a minimum rpm is simply to high to turn medium,large bowls or outboard table tops (the feed never defined what “medium or large” were).
My question is given a minimum rpm of 500 and a max of 2500 – what are my limitations on what I can safely turn with regards to bowls and outboard stuff?
If I am limited, are there ways to get around safety issues?
Interestingly, Grizzly tech support said their demo shop runs at 500 RPMs and running below that rate is not necessary.
There is perhaps no such thing as “safe” to begin with which everyone would agree with. Therefore the question is would the majority of skilled turners buy into the concept that a minimum rpm of 500 is something they could live with, or are there personal techniques that could be used to make the rpm’s “safer”.
All comments and advise would be appreciated.
Best,
Jim
Replies
It really depends on the bowl blank. If it is wet wood, large, and out of balance, 500 will be too fast and you will know it right away. Several things will help, first weight down the base (bags of sand, cement, etc.), this will reduce the lathe's interest in 'walking'. Second, if you are turning large bowl blanks, use the chainsaw, bandsaw, etc. to 'balance' them as much as possible before turning. Also, there are several ways to 'add-on' variable speed, Finewoodworkings DVD, turning bowls by Del Stubbs shows a shop built, foot peddle (may or may not work on your model).
I would start with medium size bowl blanks and slowly work my way up to find out what you and your lathe can handle. Safety includes, the usual safety glasses, safety eye shield, standing out of the way when starting the lathe, etc. etc (this comes from a turner that was hit in the face by a large wet blank, glad I had safety glasses on).
Hope this helps. Now go turn!
Jim,
I own a midi lathe with a maximum capacity of a 10" bowl. When turning a bowl, I always cut the blank to a rough circle on the bandsaw to better balance it and allow me to turn a larger bowl as well. I cut the blank freehand and eyeball the faceplate for center. As a result, the blank is always a little out of balance when I mount it. When starting, I make sure the bowl is secured on the lathe and slide the tailstock up for extra support. This is usually not necessary, but at this stage provides zero hinderance, so why not? Then I check that the blank spins freely, turn the speed all the way down (500RPM is the minimum) and quickly turn the lathe on and off. If the blank is horribly off balance and I failed to notice, this will alert me without great danger (no power). If all is well, I turn the lathe on and rough it out. It would be nice if I had a slower speed to rough with, but 500 is okay. As the bowl progresses, it becomes more round and more wood (mass) is removed and I increase the RPMs to about 1200.
Once a blank is trued up (perfectly concentric with the headstock), higher speeds are acceptable. The larger diameter of your work, the lower speed you will use. For smaller work, you can use higher speeds. This all has to do with mass and the speed (feet per minute, not RPM) at which the object spins. The edge of a 5" diameter bowl at 500RPM will travel much slower than the edge of a 24" table top.
As has already been suggested, add as much mass to your lathe as possible. Use sandbags over the base, or better yet, build a cabinet base and fill it with something. The more stable the lathe is, the less tendancy your lathe will have to shake when turning out-of-balance work.
Always wear a face shield when turning. Even if you're just turning pens or taking that final super-light cut.
Chris @ www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
The denser/heavier/bigger the chunk of wood the less out of round it needs to be to cause the lathe to "walk". I have turned bowls on a Stubby weighing in at over 500 with stand and the lathe would start walking at what I estimate was 200-250 rpms. I have turned on a Powermatic 3520 and the max speed was 186 RPMs initially (blank had a void in one section). I have had similar experiences with the Variable Speed full size Jets as well. By the way all four of these lathes are great lathes.
Lots of weight helps. Making an effort to get things relatively round before mounting helps as well. Whatever you do make sure that you use a tailstock whenever possible when you start roughing out blanks that are our of round.
twotowers,
Given that you have some time, why not make up a chart for guidance.
A 2' diameter blank turning at 500 rpm is spinning about 3000 ft./min or about 30 miles per hour on its outside edge. Likewise, a 1' diameter blank is spinning about 1500 ft./min or 15 miles per hour. The more out of round the stock, the more vibration.
The real answer to your question is 500 rpm is fine with proper preparation of the stock....and then there is 'unsafe at any speed' :)
Thanks BG;
That answer I understand!
Jim
It might be more helpful for all to understand which lathe you bought rather than the hp of the motor on it. I am sure Griz makes more than one. Also how do you plan to use it?
I'm curious, the only 2 hp, 10 speed wood lathe I see on the Grizzly web pages has a 600 rpm minimum speed, not 500 rpm. It's the G0462. Is that the one you have ordered? I see that unlike prior Grizzly lathes it has 1x8 threaded headstock. I hope that means you can use the Delta faceplaces and chucks.
I'd be a bit leary of really large turnings on a lathe where the shipping weight is only 308 lbs. especially at 600 rpm.
I had a pattern maker friend assure my that the 340 rpm speed on my Rockwell Heavy Duty lathe, was too fast. I just checked the runout on my outboard faceplate, leveled and bolted it to my concrete floor, and proceeded to turn a 35" table top from 6/4 walnut with no incident. But 600 rpm is quite a bit faster, and the Grizzley lathe not nearly so heavily built.
Steve,
Yes the G0642 is the lathe. It is listed at 600 rpm, but tec support said that it can be set up to run at 500. I currently have a very light Grizzly lathe that is essentially for turning spindles. I want a lathe that will allow me to do the other great things that can be done on a lathe; as a simple example - 20 inch diameter bowls. Based on what I have now the unit sounded like it was a well powered machine capable of doing all but the really large work that I see done on one way machines.I don't understand why grizzly would build a lathe with such a high "low" speed especially since it has a lot of horsepower for lower rpm turning.
I don't get delivery on the unit till September 10th. I don't want to spend money on just another spindle lathe. I guess I need to speak to tec support again:(
Jim
You initially asked for suggestions, so here goes.
For a lathe that will turn a 20" diameter bowl or table top you really need a slower speed than 600,or 500 rpm. A variable speed would be even better than a stepped speed model. The Grizzly lathes that I have seen are not as heavy or as stiff as I would want for a lathe to turn large, irregular shaped objects.
I own a lathe that will do that, Powermatic 3520B, but it is a much more expensive machine. But it is a lathe that will do many things well. It is a variable speed, with tremendous torque at all speeds, and very stout. The head slides to any position on the ways and can even be positioned at the right end of the ways to spin an extremely large disc outboard using a floor mounted tool rest. If you truly want a lathe to be able to turn large bowls and do not want to have to upgrade later to keep up with your needs and skills to need to look into a lathe of this size and capability. The initial investment is much greater but the long term satisfaction will also be potentially greater.
Bruce"A man's got to know his limitations." Dirty Harry Calahan
Hay Bruce & Chris;Thanks for your replies.I canceled the order on the Grizzly Lathe.Not quite sure what to do next as I can't afford the Powermatic, and I don't want a lathe hopping all over the workshop; besides Chris's forwarding web site gave me pause. I sure don't want to get hurt working with a blank spinning at a speed I can't control or is dangerous.I'm sad. Can't afford what I need....but If I relied on Tec Support....I would have gotten what I don't want!
Thanks.
Jim
Hay all (and Wing!)
What do you think of the more expensive Grizzly G0632 at $ 1,200+?
It is 220 Volt, 1 1/2 hp adjustable speed from 50 rpm's on up ( two versions of that)
could I safely ( and have the tork) to turn a 20" table top and a 18"bowl from a fairly well cut blank?
It is more than I can afford, but it sounds like it would take me safely to the next step. By next step, I don't want to spend $ 1,500.00 and only be able to turn a eight inch bowl in green wood and have the lathe jumping all around the shop!Any and all comments would be greatly appreciated.
Best,
Jim
I have no experience with the Grizzly in question, but I went to the web site and looked and that may not be a bad alternative to something like my Powermatic. Like the Powermatic it has a 3-phase motor that is used with the single phase 220v you have in your shop working through a VFD to change the rpm. This preserves the torque while giving you true low speed capabilities. The digital speed readout is nice also. It has a 440 lb shipping weight so it is probably in the 380 lb actual weight range. That is fairly heavy and it has the heavy legs that can be used as a base for some shelving with sandbags or lead for ballast. The head also slides to any position on the ways and can also be swung 90 degrees to the ways.
This lathe has a lot of good features for the money. I will not trade you this for my 3520B but it does seem to be a much better match to your requirements and at a reasonable price. Hopefully Grizzly has one in stock for you. Let me know what you decide and if you get it I would be interested to see how you like it.
An interesting story to me is how I came to buy the Powermatic 3520B that I have. I had purchased a General Maxi Lathe, midi size, and after a while decided that I wanted to turn larger stock than it would handle. My sweetie and I went to Woodwerks in Columbus to shop for a new, bigger lathe, with her blessing. I was looking at a Jet variable speed for about $1995 and thought that I would be pushing my luck to get that lathe. Well, Ron Damian, owner of Woodwerks pops over to help and I said I was looking at the Jet on display. he said it was a decent lathe but that the Powermatic 3520B sitting next to it was a lot more lathe and it was currently only $3250. To me that is a lot of money! We did look at the Powermatic as Ron pointed out it's many great features and my Brenda looks at me and says "You can get the Powermatic if you want!" Wow!! It did not take me long to make the deal and I now have in our home a great lathe as well as the great wife I married 42 years ago. Life is good!!!
Keep on turnin'!
Bruce"A man's got to know his limitations." Dirty Harry Calahan
Wing;
Thank you so much for taking the time to look at what at I wanted to buy, and for giving me your very kind input. I trust your advise and am calling Grizzly now...........thanks!! Best, and i will send you follow up.
Jim
twotowers,I was watching Norm a few weeks ago make a Martha Washington candle stand. I believe the top is 19" with a lip. The interesting thing was the setup for turning the top on the lathe. After mounting the stock on the lathe, Norm setup his router on a jig that allowed it to slide horizontal and parallel to the work piece. I'm not sure if Norm actually turned the lathe on initially or hand turned the stock into the router. At any rate, thought you might like to see a different http://www.newyankee.com/getproduct.php?0704
Hi Wing!
I did it.
I listened to all that I could find on the subject. I now know I don't want a lathe that turns at 600 rpms. But then what?Your comment was the one that told me what I wanted to know. Love to have the cash to buy your lathe and love to buy a One Way, but I can't.I have a spindle lathe and don't want to spend a lot of money to buy another spindle lathe that is no better than what I have.Thanks! I bought it! Expect delivery after September 11th.Can't wait!Best,
Jim
Sounds like you are glad you changed your mind. I have a few Grizzly tools and think they are a great value. Good luck with your new lathe. I am pretty sure you will love it. Let me know how it turns once you get it set up and running.
Bruce"A man's got to know his limitations." Dirty Harry Calahan
Wing:
I am. Safety is as big issue and I am so happy I got to understand this issue before the truck showed up!
Best,
Jim
Back when I was turning on my little PM 45, I found myself working on larger and larger hollow forms outboard. 350 I think was the low rpm, which was much too fast for the size I was doing. I put a momentary contact foot switch on it when I changed the motor to a 3 hp. With the foot switch, I could bring the tool up to just before touching the work, then start it spinning, then before it reached full speed, start turning, and slowing the rpms with the cut. When I built my big lathe, I put one on it as well. This really speeds things up, when you are reaching back into hollow turnings where you can't see where the tool meets the wood. You can't just jam it in there without knowing when it will start cutting, without worrying about it snagging and blowing out. A shielded one is a must. It is too easy to get on a foot switch by mistake otherwise. An accidental start up while you have your hands in the wrong place is serious.Did you look into getting a motor with a VF drive? You could use it along with a step pulley, and slow the motor rpm down while on your greatest belt reduction. Seems like I have seen some motor / drive combinations for reasonable prices.
Hi Wing!
This is from an old post on an old issue regarding a 440 Pound, 1.5 horse Grizzly lathe. Well I got it. I also had a severe back problem - that put me in bed for a week before it arrived. Go figure.I had a great Harbor Freight 800 LB electric hoist that I had to (gingerly) install in the ceiling----and putting the lath together (which should have taken four guys with good backs) was like slicing bread!The lathe is a dream. It is what I could afford. And it works great!I am delighted... Go Grizzly!Best,
Jim
I am delighted... Go Grizzly!AMEN.. Not a wood lathe person. Worked with many sizes of Metal lathes.Make many wonderful things! AND have fun!Now, with the NEW lathe, you MUST have wonderful tools to work the wood ALSO! Set you back a few $.
Now now, I want to try to turn out some acceptable things BEFORE I get carried away again. I got carried away in buying the new lathe to start with!
Best,
Jim
WG;Thanks for your comments. I Just turned my first bowl in what I think is Hickory (hard).The bowl came out great. To make it special I took a Propane tank and burnt the rim to give it a ebony black color and a textured top (due to the burning)On the inside I used a boiled Linseed oil to pop the grain (I think that was a mistake) then I took a light blue pickling paint and rubbed it into a nice patina. I followed up with spray lacquer. The pail blue pickeling that fades only into the grain gives the bowl a lightness that could not be achieved were the finish on the inside and the outside the same.The bowl is one you want to hold and touch. I think I have a bowl that has a lot of brilliancy point to make it attractive.Lacquers are excellent for the plastizer effect and the light reflection.. the smoothness reflects quality.
Jim
Hickory (hard). I use it ALOT!
Not sure where folks thought impossible to work with. Much easier than the Purpleheart and Jatoba I use!
Yes Hickory will do strange things when you least expect it but so does a plain old PINE BOARD! Nothing against Pine!
I'm glad it worked out for you! Have fun making chips!!
Bruce"A man's got to know his limitations." Dirty Harry Calahan
It is starting to!For the first time -in my life - as a woodworker, I got free wood!
No way you get free wood to make a desk! The town was cutting down a hard wood tree and I got a free 20 inch by 50 inch log.Turned my first bowl in the mystery wood - and even green - it was hard as iron! ...........I thought green wood was easy!!!
Not necessarily.Jim
I got a bunch of free oak and maple a couple of years ago when they were clearing some land down the road from me. They had it in a big stack and I noticed it on my way home from work. I stopped and asked the foreman what they were going to do with it and he said they were taking it to the landfill! Can't let them waste all of that: so I asked if I could have some of it for woodworking. He said "Sure, take what you want." I called my son to come over with his pickup and we took my new Husqvarna chain saw and started cutting. We took a bunch of large red oak in 8' lengths and a smaller quantity of maple and a very short piece of black walnut that I cut from a log on the bottom of the six foot tall pile. I could not unstack all of the logs to get to the rest of the walnut log and before we could come back and try again they hauled it off while I was at work! I have an Alaskan Mill for the chain saw and I cut it into different thickness boards. I sealed the ends and stacked and stickered it. I've just started to use some of the wood and I had cut the maple into roughly 2 1/4" planks so I cut some shallow bowl blanks from it a couple of weeks ago. I turned three of the blanks into bowls and was trying to get the walls about 1/4" thick and uniform and was doing a pretty good job. I got the three turned and decided to use a wipe on varnish for the finish. I applied it off the lathe and put on three coats and smoothed between coats with 4/0 steel wool. They looked great and I had 2 ready for wax. As I was steel wooling the third one I dropped it on the concrete floor and it broke (Split) in two! I was shocked! After spending a couple of hours turning and a fair amount of time finishing, I had a broken bowl. It's still laying on the bench, I can't bring myself to throw it out yet. The good part is that I can tell that I did do a really good job of turning the walls an even thickness. I remember David Marks turning a hollow vessel from claro walnut on his TV show and he was going to band saw it in two to show the camera the thickness of the walls. He laid it on a v-block on the band saw table, started the saw, and then just stood there looking at what he was going to do! He looked up to the camera and said "You really don't appreciate what I do for this show." Now I really understand what he meant.
Hang in there and look for more of that free wood. It's out there and many turners NEVER buy wood, it is all donated from downed trees, storms or landscaping changes. Regardless of the cost, we usually have a greater investment in our time than we do in material cost.
Bruce"A man's got to know his limitations." Dirty Harry Calahan
Wing;
Reply to an old post:regarding my purchase of a wood lathe.
GO GRIZZLY! at $1200.00!!!
Wing I am happy as a dusty clam (East Coast Joke!! yuk-yuk)Jim
OK, you forced me to take the shrink-wrap off my 2008 Grizzly catalog and look up the lathe you're interested in. Now I can't sell the catalog as brand new on e-bay! Is there any way to get a different (smaller) pulley for the motor? If you're planning on turning a lot of large stuff, you may not need or want the last 2 or 3 high speeds (rpm).
Many, many years ago I worked on a wood lathe that had a friction brake built INTO the headstock. When we turned large pieces (outboard) one of us 'rode' the brake while the other did the turning. It was, if memory serves me correctly, a 3 phase lathe with tons of torque. What I'm thinking of is called a 'pony brake.' Is it possible (safe?? sane??) to rig up such a brake just to scrub off 100 to 200 rpm?? You wouldn't use the brake all the time, just for the first few minutes to get the piece of wood centered.
Or.... is there some sort of speed control that can be added to slow the motor down those extra 100 to 200 rpm?
SawdustSteve
Sawdust, having broken the seal of your Grizzly catalog (sorry I made you do that, as it is no doubt a collectors item)Well I am befuttled! If you looked at the Go462 it has horse output like the big boys, but it turns at what appears a dangerous rate of 600 rpms for it's initial speed.
Soooooooo Grizally has another lather the go632 at three times the money
!!!three times - and it has lower horsepower!
I am trying to buy "the last lathe" that fits a reasonable budget. I am lost. I want to turn interesting pieces with a machine that can do the load, and i want to do it safely.
Sawdust, if you were short on cash but wanted to buy a unit that would give me a robust machine that had very little limitaations what would you do> PS: I cant find good used lathes in my market.
?Jim
Jim.... If you don't see what you like, wait a few weeks, unless you have a project that MUST be taken care of immediately. Something will show up, either new or used. Have you checked with your 'local' woodworking club to see if anyone has what you want?? If you scroll down on the opening Knotts page, there is a club listing. It's almost to the bottom of the page. My preference is a lathe with a seperate motor, not mounted on the head. That way, you can change motors or pulleys to get the combo you want. I've had bad experiencees with the older Rockwell variable speed lathes. It would not hold a speed. The locking handle always needed attention. Yea, changing belts (speeds) can be a royal pain on some of the older units, but you can always change the motor end pulley and get 1 rpm if you want.
SawdustSteve
Hi Saw!
I tried all the turning clubs from Maine to New Jersey (I live in Connecticut, and nothing is for sale at any of the Clubs. Craigs list, Ebay .... nothing. You would think something would be there aside from underpowered spindle lathes.
I learned that a lathe that didn't turn under 600 RPM was something that was in a word dangerous for what I want to do. So I canceled my order.I bought the high end variable speed Grizzly. Thanks so much for your reply. Best,
Jim
Jim,
Here's an excellent resource on the subject: http://www.woodturnerscatalog.com/woodturners/Images/safe_lathe_speeds.pdf
Chris @ www.flairwoodwork.spaces.live.com
- Success is not the key to happines. Happiness is the key to success. If you love what you are doing, you will be successful. - Albert Schweitzer
Chris;
Thanks. You helped me make a decision not to buy the lathe I was discussing.
Best,
Jim
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