Home-made bowl lathe

I am considering a home-made bowl lathe. I haven't yet looked at it, so I'd like to discuss what to look for.

The structure of the lathe is 3 heavy steel I-beams. The bed beam is about 7' long, and sits atop two shorter (about 30") cross beams, which form the base. Massive locking wheels. Weighs about 500 lbs.

The motor and spindle are mounted on 3 stacked-and-welded-together pieces of what looks like 6" square steel tube, each about a foot in length. The motor is a 1 hp Leeson direct current permanent magnet motor, with a Leeson Speedmaster variable speed drive. Runs on 240 or 120 volt. There is no tail stock. A fairly massive tool rest. Several face plates; no chuck included. Don't know the spindle size/threading yet. The swing must be about 36", plus or minus.


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Concerns:

1. Is the motor under-powered for something this massive? Replacing the motor would probably be expensive.

2. Don't know the speed range; will take a laser tachometer and check it out. What would you suggest is a desirable range for this sort of lathe?

3. How can you assess the condition of the spindle bearings? This thing is old.

4. The spindle drive pulley is exposed at the back end of the spindle. Not the safest setup!

I"m thinking it might be worth taking along a big bowl blank of the sort I'd probably use on it, mounting it on the face plate, and give it a spin. See how it spins up, how the tool rest fits, etc.

What would you be looking for, besides the above?

2hp minimum for a big bowl lathe.

I would consider ease of use. Can the tool rest be moved around with any finesse? Is the spindle a common thread so accessories are easy to obtain? Are the spindle bearings in good shape?

unless those beams are made of aluminum, I'd guess it weighs a lot more than 500#

My eyeball thinks that the tool post looks light and there will be flex in the extended position. Also a single belt will have problem delivering enough power for large bowls and the 1HP seems under power thinking about my 2HP Powermatic 3520B with wide multi-groove belt.

Well, I don't think I would call it a bowl lathe, but you probably could put some porch columns on it. For a lathe that size, if you are wanting to do bowls, I would put a good 3 hp 3 phase motor on it with the 1 inch wide belts, and probably 2 or 3 speed ranges. If you are planning to max it out with a 36 inch bowl, then 3 hp for sure. Cheap, maybe, but you would have to put a lot of work in it.

robo hippy

My opinion is that even if it were free, any money that you spend on it trying to remake that Rube Goldberg into the lathe that you really want will be money wasted.

Something else to consider is that with those soft tired wheels, and relatively narrow stance, is if you get a out-of-balance bowl blank on that thing, it is is going to bounce all over. If you buy it, one of the things for you to consider is putting some feet on the ends of those legs that screw down and make solid contact with the floor.

I tend to agree that despite the lack of a tailstock, that is suitable for turning columns not bowls. Typical dedicated bowl lathes have just enough bed to hold the tool rest (and tailstock until it can be removed) but allow you to stand at the end to turn. With this beast, you would have to straddle the beam.

During the time that this piece of junk has been listed on Clist there was a really nice bowl lathe in Atlanta listed for $900. That appeared to be a good deal.

I am not as negative about this machine as Harold but don't care much for it.
1 hp is too small for this much swing
A single I-beam does not have nearly enough torsional stiffness to support the tool-rest for large diameters, it will flex driving you crazy.
If it really weighs 500 lb; that is too light, 1500 lbs would be much better.
If you do decide to buy it, don't worry about the bearings too much; they could be replaced fairly easily for reasonable cost.

A lathe with that long bed isn't a true bowl lathe. The motor is way too small. I had a bowl lathe custom made by John Nichols. It had a tailstock which I seldom used. It had a 21 inch bed which allowed me to turn while facing the vessel. If you are going to turn HF's that is a must for hollowing. It weighed 800 lb. but it had a container built in for sand. I had 400 lb of sand which gave me a 1200 lb lathe. It had a 3 hp DC motor. The motor was v speed with speeds of near zero to about 2000 rpm......it was a very satisfactory lathe and I would still have it I had room in my shop.

Quote:

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Originally Posted by Dennis Ford

I am not as negative about this machine as Harold but don't care much for it...

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I don't see Harold as being negative. He is giving a perhaps brutally frank, but yet honest answer that will serve the OP much better than responses that don't take a hard nosed look at what he would be getting versus what he really wants -- which I assume is to be able to turn really large bowls.

i would suggest that the OP start off by looking at one would expect to find in a heavy duty bowl lathe. Look at the VB36, the Robust AB, the Vicmarc 300, and the Oneway 2436. Aside from the obvious things like power and structural rigidity is conformity to standards that enable it to used with myriad of accessories that are available. If the spindle doesn't have standard threaded nose and Morse taper socket then that is a very serious limitation. It appears that the tool rest is another deficient part of this lathe and how many of us would honestly say that we wouldn't mind if we had to give up the tailstock on our lathes. BTW, I see the bed is a WF beam and not an I beam.

So, what what features does this Franken-lathe bring to the table?

• A midi lathe size motor
• flexible structure to get you into the "sway" of turning
• an absurdly long bed (unless making columns)
• a headstock that probably can't accept accessories such as chucks and drive centers
• a clumsy tool rest arrangement that probably isn't exactly amenable to moving and height adjustment
• Who needs a stinkin' tailstock anyway
• wheels to give it that needed bit of "bounce"

If I were related to the seller or if I liked to tinker with stuff more than I liked woodturning then I might say, "go for it". But, in good conscience, I can't offer any encouragement beyond suggesting things to take into consideration and not be blinded by visions of massive bowls.

1. Is the motor under-powered for something this massive? Replacing the motor would probably be expensive.
All this depends on how much the lathe is, but to make into a nice VFD controlled 3 hp is not that bad.
http://dealerselectric.com/item.asp?...=132&PID=24075

This is just an example of what you can do. There are cheaper options as the HP is reduced. Again, depends on what the lathe costs.


2. Don't know the speed range; will take a laser tachometer and check it out. What would you suggest is a desirable range for this sort of lathe?
I'd prefer 0 or 100 to 1000 for big stuff

3. How can you assess the condition of the spindle bearings? This thing is old.
Most likely all you can do is grasp the spindle and try to rock it. It shouldn't show any play. If it runs, then start it up and listen to it, they should be quite.

4. The spindle drive pulley is exposed at the back end of the spindle. Not the safest setup!
Adding a guard shouldn't be too tough.

You could compare it to what Lissi Oland uses to turn bowls. Big bowls.

https://www.youtube.com/watch?v=1PME...feature=g-vrec

I don't remember what she said about the motor horsepower, but you can at least see about what speed she used. Cores with a chainsaw!

Wonderfully friendly person, always has time to chat. The last time I visited (right before she moved back to Denmark) she loaded up my vehicle with some great wood.

JKJ

Interesting setup. I'm not a huge fan of I-beam like that, but if you are starting with fairly balanced blanks, it's likely ok.

1-under powered? Maybe. That's a pretty large gear reduction, say 4 or 5 to 1. Assuming a standard 1750 rpm motor, you have 300-400 rpm natively. The controller on the front looks like my Leeson DC unit. If so, a DC motor has lots of low end torque. It might work quite well.

3- bearings are standard pillow blocks. Replacing those, if necessary, Is cheap. Check the Big Bearing Store.

4- pretty normal in the old days. Mine are exposed as well. Have put my arms, hands on the pulley many times while running. No issue...ok I wear gloves. Just don't put your fingers under the belt. Or, make a guard over top.

stability would be the big issue. Remove the tires, bolt it to the floor.
i-beam flex would be my next concern. Bolt a perpendicular beam near the headstock, and fix that to the floor.

Btw. Mine is a DIY solution as well. twin 10" I-beams, 32" swing, now with the above mentioned perpendicular beam (and 7.5hp) all cemented down to the floor. It works well as a bowl lathe for blanks of several hundred pounds.

With a little work, this could be good machine, just won't be plug and play. And I'll bet it's a LOT more then 500 lbs.
Olaf

Quote:

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Originally Posted by Josh Bowman

1. Is the motor under-powered for something this massive? Replacing the motor would probably be expensive.
All this depends on how much the lathe is, but to make into a nice VFD controlled 3 hp is not that bad.
http://dealerselectric.com/item.asp?...=132&PID=24075...

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That is a start, but we need to look a bit deeper than the motor HP to know for certain what we are getting. The inverter is a basic volts per Hertz which is OK, but it won't have the same performance as the higher quality sensorless vector controllers. That's not a huge deal ... the Powermatic 3520 uses a basic v/Hz controller and the only time that speed regulation is a significant issue is at very slow speeds.

The motor is a basic general purpose three phase motor and the specs show that it is rated for inverter duty ... which is good. However, it does have some caveats which could be troublesome. The motor is not designed for operation over base speed ... In other words, it shouldn't be operated faster than 1740 RPM, so 60 Hz is the highest frequency allowed. There are two typical modes of operating a motor with an inverter: constant torque and variable torque. This motor has a full load torque rating of 9 pound-feet and if the inverter is programmed to allow full load torque as the speed is reduced, then the minimum motor speed must be restricted to just over 400 RPM. The reason for this minimum speed restriction is overheating due to insufficient cooling air. If we choose to operate the motor using the variable torque mode, the minimum speed is about 170 RPM, but with a significant performance penalty where the maximum allowed torque is de rated in direct proportion to the motor speed ... in other words, at half speed (870 RPM), the maximum torque will also be one half of full load torque (4.5 pound-feet). We can easily see that operating at minimum speed of 170 RPM Will really cramp our big bowl turning style if the maximum torque is limited to only 0.9 pound-feet.

In the real world we usually aren't operating the motor at the limits of its performance envelope so we might be able to cheat a little, but only a little ... And we don't know if we have pushed the limits too far until we discover that we have pushed the limits too far. Motors usually die gracefully and not suddenly so we don't notice the very gradual decrease in performance. Inverters, on the other hand, aren't so nice about expiring.

The headstock needs support braces or boxed in , the i beam is gonna be in the way for bowls . the banjo needs a leg to the floor after the ______is bolted down . if you are a machinist it could be patched up , but then just build a lathe with tail stock . If its cheep buy it and scrap it out motor is worth 100 $ and the wheels are same or more .