lathe balast

[fshenkin94]

Just picked up a used delta 14" lathe, thinking that I could turn some larger bowls than my Jet mini allows. I mounted a piece on the lathe (about 13" round on a face plate) and find that the lathe is really jumping around. I got the face plate as centered as I could. Any suggestions for some sort of balast to keep it from doing that.

 

[marcruby]

The standard is sand bags or concrete blocks. I know one guy who welded in a big tank and filed it with water. Every once in a while I forget that my lathe is set at 'pen' speed and slap on a blank, turn it on, and watch it try to mate with my bandsaw.

In general, start at a controllable speed. Once you've got the piece roughed out you will be able to turn up the speed. As a rule bowls are best turned at about 500 to 700 rpm.

Marc

 

[spiritwoodturner]

Sell it and buy a Powermatic!!! Just kidding...a little. I've seen guys turn these lighter lathes into a bunker, and they still hop around. Weight equals stability and smoothness, and my Powermatic weighs over 750 pounds. Smoooooth and solid as a rock.

Good luck,
Dale

 

[Fred]

The FIRST RULE OF THUMB is to N E V E R turn on any lathe without FIRST turning down the speed. To turn on a lathe and not reducing the speed from the last time it was used is just a sure fire way of getting seriously hurt. Not to mention that the possibility exists for you to have to deal with a large projectile flying all over the place destroying itself and anything/anyone in its path.

If you do not have an adjustable speed lathe and you intend to turn a large bowl you should reduce the belt to the lowest speed. Then turn the blank down to being round.

If you do not start slow you will sooner or later destroy the lathe's bearings and/or the drive mechanism from all the vibrations. The vibrations come from the fact that the blank is out of round and therefore out of balance. Same principal as an automobile tire being out of balance.

All it takes is common sense to realise that if the piece is shaking the crap out of your equipment then something is seriously not right. It is not a race to get finished so why be in such a big hurry.

Marc says the 500 to 700 RPM range is good for bowls. Well, I must be different since I start off at 350 or so just to test the blank balance then I proceed to increase as I get it rounded. I am usually turning at 2800 - to 3200 RPM by the time I am finished. Then I slow back down to 500 - 800 to sand and then apply my finishes.

BTW, pre-cutting your bowl blanks to as round as possible on a bandsaw is common practice to get started.

SLOW down in the beginning and increase speed as things start to come together. This is also one of the better reasons (IMHO) to having a variable speed lathe in the first place.

 

[randyrls]

Just picked up a used delta 14" lathe,Any suggestions for some sort of balast to keep it from doing that.

One trick I've seen is to put a pin, nail, screw, anything with a point pointed up thru a board etc. Balance the bowl blank until it is reasonably balanced, and give it a good whack to mark the pin. Center it on that mark.

The suggestions to start as slow as possible is a good one too!

 

[JimB]

You can use almost anything for balast. I have one of my lathes in the garage and I use 2 large bags of Scotts 4 Step Lawn furtilizer.

However, as already pointed out, if it is vibrating as much as you make it sound it is, you probably need to find out why. Adding a lot of balast is not a good solution. Is it out of round? Even a little out of round can cause a lot of vibration. Round it on the bandsaw. Turn down your speed as low as you can and then speed up as you get it rounder. Is the piece of wood too big? You said its 13 inches round. How long is it? (this will also compound the out of round issue). Just because you can mount it on your lathe doesn't mean you should or you should start with something smaller and work your way up to this piece.

Turn safe.

 

[Vince_Hoffmann]

Every once in a while I forget that my lathe is set at 'pen' speed and slap on a blank, turn it on, and watch it try to mate with my bandsaw.

So, bandsaw + lathe = planer? :biggrin:

 

[marcruby]

I assume you make very small bowls. Turning a 6" bowl at 2800 is about the same as turning a pen at 34000 rpm. That means the rim is going about 50 miles per hour. I hope your face shield is a racing helmet. Nice way to kill yourself or somebody else on a bad catch if I might say so.

To save everyone from measuring the circumferences of their pens and bowls, there is a formula -- Diameter * rpm should fall in the range between 5000 and 8000. If you use this the maximum speed for a 6" bowl should be 1300. A 10" bowl about 800.

Spindle turning speeds can be higher, but the point is that what shapes the wood isn't the rpm of the lathe, but the amount of wood turning under the tool.

Marc

Marc says the 500 to 700 RPM range is good for bowls. Well, I must be different since I start off at 350 or so just to test the blank balance then I proceed to increase as I get it rounded. I am usually turning at 2800 - to 3200 RPM by the time I am finished. Then I slow back down to 500 - 800 to sand and then apply my finishes.

 

[firemedic]

I built a 2x10 studded bench and used a waterproof exterior plywood bottom. It worked pretty well for me. I filled the voids between the 12 inch center studs with about 400 lbs of cement and bolted it to a foundation wall. My Jet 1442 came without a stand but i think it worked out. I lag bolted the lathe to the bench and away I turn.

Ryan

 

[TellicoTurning]

I have two lathes.. one is a Jet 1014 mini that I built my own stand... the bottom of the stand has a box the length and width of the stand and about 1 foot deep filled with gravel. The second is a Jet 1442 that has a cast iron base and weighs about 450 lbs... I haven't yet, but plan to put a box in the slots on the bottom of the legs and will fill that with gravel also to stabliize the 1442. It's heavy enough not to need a lot of weight, but will help with the out of round blanks initially. It's slowest speed is 450 rpm, and really wish I could go lower at the start a bowl.

 

[JimB]

I hope one of the more knowledeable folks chimes in here but I thought you should NOT bolt the lathe stand/table to the floor/wall. You should only add weight to it. You attach the lathe to the stand and weigh the stand down without bolting it to the floor/wall. I don't know the reason for it but I do know some very experienced turners (not here on IAP) who have said this.

 

[TellicoTurning]

I assume you make very small bowls. Turning a 6" bowl at 2800 is about the same as turning a pen at 34000 rpm. That means the rim is going about 50 miles per hour. I hope your face shield is a racing helmet. Nice way to kill yourself or somebody else on a bad catch if I might say so.

Marc

Marc,
I agree about high speed for bowls... last fall I was turning an 8" dia x 1 1/2" deep Zebrawood bowl on a chuck... I think I was turning at about 1800 cleaning up the inside. I got a little cocky and didn't pay close attention when I stuck my scraper into the bowl... evidently I didn't lay the tool on the tool rest before I pushed in towards the bowl... I had a catch that slammed the tool onto the tool rest, sheared the cross bar right off the 5/8" post... I had steel flying in one direction, a bowl flying in another... I had both arms over my head and was ducking for cover. I pay close attention now when I approach a bowl and about the top speed is now about 1100 rpms..

 

[Rifleman1776]

Do heed what Fred said. Understand that not all lathes are suitable for larger bowl turning because they my lack (1) a really low, low speed; (2) power needed for that kind of turning; (3) sufficient weight.
Adding weight is always a good idea with lighter machines. A plank across the legs with sandbags is very good. Sand absorbs vibration. Concrete blocks and large rocks do not absorb vibration well.
Do you know what your lowest speed is? If it is over about 300 rpm, you should stay away from trying larger bowls.

 

[stolicky]

So, bandsaw + lathe = planer? :biggrin:

I'm thinking more like a circular saw! : )

In all seriousness though, round as possible 'before' it get mounted on the lathe. Then, start 'slow'.

 

[marcruby]

I got a little cocky and didn't pay close attention when I stuck my scraper into the bowl..

I have a long story about the bowl that was saved by my nose. >

Marc

 

[MobilMan]

One good habit to get into, especially on larger variable speed lathes, is turn it to slowest speed BEFORE turning it off. I do that on my Grizzly, & for some reason still do it when I'm using it for buffing a pen.

 

[DocStram]

If you're talking about the Delta 46-715 that's the same lathe I have. I've turned 12 - 13 inch bowls on it without a problem. I have sand bags on the bottom ... and it is definitely NOT bolted to the floor. Before you even mount the blank make certain it's as round as you can get it on the bs. Then start slow .... real slow and work your way up.

 

[Randy_]

Just a comment that may not be obvious to some.

Even if you load up your lathe with thousands of pounds of ballast so it is rock solid, the imbalance of the blank is still there. The forces generated by the spinning unbalanced blank that caused the lathe to move around are no longer partially dissipated by the lathe movement and are now totally absorbed by the bearings and drive train of the lathe greatly increasing the wear and tear on those parts. Do everything you can reasonably do to see that your blanks are well balanced before they go on the lathe.

A large blank that is not well balanced could be a big problem even at 300 RPMs. I have read that folks who have lathes with the capability will start off as slow as 50 RPMs in such situations.

This discussion got me to thinking in a different direction. I know how badly a car can shake if it has an unbalanced tire that is off by only an ounce or two and a car weighs several thousand pounds. How fast do you suppose that wheel is spinning when the car is traveling at 60 MPH?? No need to do the math.......I've done it for you......but if you were guessing??
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The answer is about 800 RPMs. It depends a little on what size tires you have; but 800 is a ballpark figure.

 

[Rifleman1776]

One good habit to get into, especially on larger variable speed lathes, is turn it to slowest speed BEFORE turning it off. I do that on my Grizzly, & for some reason still do it when I'm using it for buffing a pen.

Not just a GOOD habit, but an absolute requirement for safety with many lathes.
My new lathe is an electronic variable speed and has a 'soft start'. Great feature, speed builds up slowly. If a blank is off balance and you see things are starting to get to wobbly there is a large red emergency shut-off button that can be hit and everything stops before disaster happens.

 

[Tree Frog]

The best way to limit the vibration is with a variable speed lathe, so you start slow, below the vibration point and creep the speed up as you improve the balance of the blank. The ballasting just transfers some of the vibration from the headstock bearing as others have said here. Actual top speed will always depend upon the item being turned. I've got a redgum burl on my stubby now, that after many, many hours of rotation, is able to be turned at 160rpm and the stubby weighs in at a light 880lbs before any addons. The bowl will never bee in balance and is down to 21" accross.
When getting started, I fitted some balast to the faceplate to partially offset the imbalance. It was a block of lead that was movable along a board that was bolted between the faceplate and the burl. As I got more rubbish off the burl and the vibration crept up, I moved the weight intowards the centre a little. This helped somewhat, but only allowed in incease of somethimg like 30rpm, and would have been another issue if the bowl had of departed the lathe in an uninvited manner. I could have been conceiving a planer even though the bandsaw is way across the shed.

I've tried to add a pic of the balance weight - not sure if I got the process correct.

The only reason I've heard of for not dyna bolting the lathe to the concrete if that if you do get a big vibration, the lathe will most likely pull the bolts out of the floor along with nice cone shaped bits of concrete, as the dyna bolt grip is stronger than the concrete. Then you have your lathe on bent standoffs and toe traps in your floor. Neither is an attractive look, I would suggest.

I sold my non variable speed lathe as soon as I could justify an electronic speed controlled machine, and then made sure I got ones where the control would function down to a very low speed as well as the motor providing good torque at that lowest speed.

So there are a lot of words to say what others have said in much less. Hope its of interest from a newby

Greg

 

[Doghouse]

Ok, so everyone here has explained quite eloquently that you should start slow. Most of my turnings are done at the lowest setting that I can get a clean shaving at. That being said, I milled some boards to fit inside the base of my legs, then put 3/4" plywood on that. The base was racked a little, but now is square. On that I placed 8 bags of cement. The headstock may rattle, but the body of the lathe never moves!

 

[Randy_]

.....The headstock may rattle, but the body of the lathe never moves!

That rattling you hear is your HS bearings and other lathe parts wearing out prematurely. Do your self a favor and try balancing your blank a little better before you start turning!!

 

[Doghouse]

Of center turnings are by definition off center and therefore never in balance.

When doing these types of turnings your headstock will rattle if it is not bolted to the body of the lathe. If you have a sliding headstock you will have rattles. While not optimal, it is the nature of the beast for those types of turnings.

 

[Rifleman1776]

Of center turnings are by definition off center and therefore never in balance.

When doing these types of turnings your headstock will rattle if it is not bolted to the body of the lathe. If you have a sliding headstock you will have rattles. While not optimal, it is the nature of the beast for those types of turnings.

Sorry, not correct. A sliding headstock, when locked in place is solid. Period. If it rattles, it is either not locked or, as pointed out, bearing might be shot. My previous lathe had a sliding headstock and it never rattled when locked in place. My current lathe has a sliding headstock and doesn't rattle when locked. I wouldn't tolerate a lathe that had such a bad feature. The head stock must be solid or you don't have a lathe.

 

[spiritwoodturner]

I have to agree totally with Frank. When my Powermatic headstock is secured to the bed, nothing on heaven or earth can make it rattle against the bed. It's virtually "welded" to the bed. There is zero chance of rattling, unless of course something in the cam system is broken. Then it will be painfully obvious, as eventually it will fall off on your foot. It weighs nearly 200 pounds. When it hits your foot you will feel it. Then, you'll have a positive answer as to what was making that rattle. But that is NOT part of the sliding headstock design. I've put huge, unbalanced stock on this lathe (natural edged stuff CAN'T be balanced, except with blind luck), and using the basics of correct speed (although that can't be stressed enough to new turners) and common sense I've never had a lick of rattling. That's not to say Powermatics or ANY lathe are immune to bearings failing at some point. But my original premise holds, IMHO.

Weight is good. And not just in the legs, but in the bed, and the headstock.

Greg, I must say that is one interesting looking contraption you've come up with for balancing stock! I guess my first concern would be if the nut holding that weight ever slipped, but I'm quite sure you've wrung that out already. Very interesting indeed. You should market that, and with any luck, like Paul Huffman, you'll never have time to turn again!!!

Dale

 

[babyblues]

When getting started, I fitted some balast to the faceplate to partially offset the imbalance. It was a block of lead that was movable along a board that was bolted between the faceplate and the burl. As I got more rubbish off the burl and the vibration crept up, I moved the weight intowards the centre a little. This helped somewhat, but only allowed in incease of somethimg like 30rpm, and would have been another issue if the bowl had of departed the lathe in an uninvited manner.

I've tried to add a pic of the balance weight - not sure if I got the process correct.

I sold my non variable speed lathe as soon as I could justify an electronic speed controlled machine, and then made sure I got ones where the control would function down to a very low speed as well as the motor providing good torque at that lowest speed.

So there are a lot of words to say what others have said in much less. Hope its of interest from a newby

Greg

Two very good points, Greg. First, rig some sort of counter balance to the piece. Second, the lower gear settings produce more torque.

Doghouse, along with adding weight to your lathe and using a lower setting, I would try something like the picture Greg posted. I've seen a setup for turning multiple center pieces that was very similar. Of course, they were done on a bigger lathe, but the concept should still work on a smaller scale with a single center turning.

 

[fyrcaptn]

weight

physics are amazing. as said it isn't just about weight. When the machine 'tries/needs/is going' to move and can't, the forces are going somewhere! Bearings, joints, whatever is weakest and/ or most expensive probably~
Overdoing it is easy. Available swing doesn't mean the machine can safely handle a piece that we make fit.
I don't know a lot of math, but I had a large platter that blew one day. After introducing itself to my nose, forehead, truck mirror, and porch light ( I can't swear to the order) I found it in the neighbor's yard over 75' away from where it started. Well parts of it.
Lot to be said for safety equipment ( I WISH I had had at the time). There wasn't time to think about ducking because it was over before I realized it had started.