Opinion wanted on this variable speed option.

I am looking for a little input in case I have missed something. I found an old J-line bowl lathe and bought it. I am have been looking for a motor to power it. I have looked at a bunch of motors, controllers, AC, DC, 3-phase, single phase etc. I think I have settled on a DC motor largely because of cost. After some searching and a lot of scrap paper math I think I have made my choice. I have found a 1 HP totally enclosed motor, 1725 RPM, sealed unit and rated for continuous duty. It costs more than some of the other DC motors but it seems the better choice in a dusty environment like a lathe. It

Having no experience with DC motors I have some concerns about the loss of low speed torque. My plan is to run a variable speed control and since my lathe came with a 3 step pulley on it and I I have decided to use pulleys with a 3", 4" and 5" diameter and a second one with a 1

5/16", 2 9/16" and 3 3/8" dia. That way If I need to I can run the motor at a higher speed and keep the spindle speed down and torque up.

On the lowest setting my max. spindle speed would be 455 RPM and I have close to a 4 to 1 multiplication factor in my favor, so even at very slow speeds I should still have plenty of torque. The next step provides for 1120 RPM and a 2 to 3 ratio. The highest setting is almost 1 to 1 and would be way faster than I think I would ever need.

While I hope to just set it and not have to change the belt location at least if I find that at slow speeds on larger items that I am lacking torque I have the option to gear it down and speed up the motor. Or have I missed something here?

Reply to
Kudzu
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Kudzu, I am not familiar with your lathe, but have a few comments. Variable speed is a luxury that once you have it, you can't imagion turning without it. I like speeds down to 0 and up to 3000. 500 rpm is very fast for a chainsawn 12 inch diameter blank. Unless the lathe is very heavy, you may end up chasing it aroung the shop. For a 18 inch bowl blank, it is down right scary. For turning 1x12 inch spindles, 1000 rpm is very slow, 3000 or more is fine. The speed sounds scary, but when you think about it, it is a matter of 'feet per minute'. A 12 inch bowl at 500rpm is going at the same of more fpm than a 1 inch spindle (I didn't do the exact math, but you get the idea). The more I turn, the more comfortable I am at higher speeds, as long as the lathe and what I am turning isn't shaking too much. If all of your turnings are perfectly balanced, 500 rpm is fine. It is nice to start out at 0, and up the speed slowly to see how well balanced and secure the blank is before you begin to turn. robo hippy

Reply to
robo hippy

SNIP

Roy Underhill is on in an hour and a half. Love watching him take a curl off while rotating the piece at less than 1 rpm....

Reply to
George

I think you should be OK to the extent that it is worth a try. You might find you do want more than 1725 rpm sometimes for small diameter stuff. I wonder if the 1-5/16" dia pulley is going to get enough grip on the belt to start rotating a big blank - I have a small pulley on my bandsaw and it can be a problem slipping.

Are you using a commercial DC motor controller? They should have a better torque/constant speed characteristic than just varying the DC voltage open-loop.

Good luck, Billh

Reply to
billh

I agree with r h, Starting from zero rpm or even varying the speed between belt changes was once a luxury and still may be for mini lathes, but IMO for today's larger lathes, the luxury has become a necessity. Reminds me of the 'luxury' of powering the brakes, steering and windows on cars. I thought when they first came out they were just luxury lily gildings. Same with scroll chucks, revolving tail centers and grinding jigs. My dad probably felt the same way about self starters and Skill Saws, a crank and a Disston were 'good enough' for him. :)

I won't bring up the Luxury of movable headstocks or lathe beds. Too many of my friends have "Noway" to do this and besides I'm not in COC mode. :)

Turn to Safety, Arch Fortiter

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Reply to
Arch

Well the lathe is a casting and about 50 lbs. Not heavy enough for nothing. But I am building a stand for it and I plan on making it very sturdy and with a place to add sand bags for weight. I am going to start at 300 lbs or so and go from there. After all sand is cheap.

If you want to see a photo of the lathe here is the URL

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It's just sitting on my table saw outfeed table. Of course the key to this is going to be the stand it's on. It will make or break it. BTW I used to be a mechanical designer in a previous life so I am very familiar with Surface Feet per minute and totally agree with you on the speeds. I have turned a few rough blanks on a on craftsman lathe with no weight and not enough slow speed. Scared the hell out of me when I hit the on switch!

I am not sure if you understood or not but I should have speed of 0 and up with the speed controller

Reply to
Kudzu

Well my top speed, if I use the fastest combination is 1977RPM. I don't expect to do much small stuff on this lathe. I 'expect' to just be turning larger bowls and hollow forms. But you never know of course. I am looking for a Delta/Rockwell lathe to go with this one. I want to add riser blocks to it. This lathe is not suitable for spindle work as it has no tail center. I see down the road using both lathes in conjunction with one another.

Interesting point about the small pulley. Had not thought of that. I can go with a 2 inch and 6 inch on the second pulley and get about the same speeds but a 6" won't fit in the existing guard. I can of course build a new guard but really don't want to do that. I am hoping/expecting that I won't have to use the smallest pulley at all.

The motor controller is a Reliance Electric 230V pulse width modulated controller. I found it at the

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I am can the motor and controller for $200. The motor is matching Reliance commercial model, not one of the treadmill motors. I looked at those and decided against it. Plus I really like the TEFC enclosure on a lathe.

Reply to
Kudzu

Which is where zero to X variable speed really shines: you tune the speed for the work.

Reply to
Lobby Dosser

Hi Kudzu, Seeing the picture changes the approach I would take. For me your lathe is a wonderful piece of machinery to enjoy and restore to what it was. Please don't take this as a put down, I would love to own it. I don't know what a J line is, but unless the pic is very misleading it was designed for light & balanced turning, perhaps for a special purpose. Maybe it is wooden bed spindle lathe with tailstock missing. Maybe it is a disc or platter lathe. Maybe I'm lost out in left field. :)

For general bowl turning in the 14- 16 in, size the spindle and tool post 'appear' undersized. The toolrest 'appears to have little or no vertical adjustment. The head casting doesn't 'appear' to be very robust and the bed 'appears' short even for a bowl lathe. Maybe like so many 'heavy duty' 1/4 hp split phase home workshop power tools of yesteryear, it never really was HD, but it sure is a fascinating lathe.

I have no training in mechanics or in machine design, but there must a limit to what a heavy and well engineered stand, slow speed and increased hp can do, else we would all construct massive stands, put 50 lb lathes with jack shafts and 3 hp motors on them and turn big heavy bowl blanks.

Can you tell us more about your interesting J line lathe. I may have the specs and what should be done entirely wrong and my take may be a waste of bandwidth. (not the first time) Whatever you decide to do, have fun and tell us about it.

Turn to Safety, Arch Fortiter

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Reply to
Arch

Hi Arch

I think you are absolutely right Arch, you can see the lathe is well made , but is not made for anything heavy, stool top or small table top or such come to mind. If one would try to turn some rough blanks on it the first catch would break the banjo, and I think that would be a shame, much better to restore and use for it's designed purpose than to try to make it do what it's unable to do, however I am not the one to decide here.

Have fun and take care Leo Van Der Loo

Arch wrote:

Reply to
Leo Van Der Loo

I have a 1 hp, 5000 rpm motor and it works real well for most things with speeds in 3 pulley settings approximately the same as yours. This is obtained with a jackshaft. I have turned up to 18 inch bowls and you can turn it down slow enough to be very comfortable. My top speed in top pulley setting is 2000 rpm and the top speed at lowest pulley setting is between

400 and 500 rpm, so just about the same. My motor and controller cost me $50 or so from Vega when they bought a whole bunch of surplus. I can actually turn it down to something ridiculous like 1-10 rpm or less in the lowest pulley setting.

I have a reversing switch and a potentiometer mounted in a white painted box from a home store. I bought a blank faceplate for the box and drill holes for these in the face. The wires are in a split, corrugated flexible tube like used in some autos. I epoxied magnets on the back of the box and can move it to different positions on the lathe.

I turn only bowls and sometimes I wish my speeds were a little lower so I could be at the full 1 hp more of the time. Pens and tiny objects might want over 2000 rpm. The larger the motor you get, the less optimized your pulley ranges need to be.

Derek

Reply to
Derek & Sara Hartzell

My Internet service has been down. I was on the tractor doing some landscaping and came in the house to find no TV or Internet. It seems that they didn't bury the cable very deep. DAMHIKT. :-)

OK, I was fortunate to actually get the manual with this lathe. It was made by Brodhead-Garret of Cleveland Ohio and is called a J-Line Bowl lathe Model J-116. There is no date in the manual unfortunately but the book makes me think 1940's. Arch, your very much on track and bring up some good points that in my excitement I must admit I have not considered. The manual doesn't have much information in it on the lathe itself. It concentrates on instructing "how to turn". The lathe was clearly made as a bowl lathe for making bowls, platters etc. The lathe was clearly intended (based on the manual) for faceplate turning. It doesn't mention what it came with in the manual but mine has (3) 7" faceplates

The manual shows diagrams of large bowls (14" dia), platters, hollow form (6" long) and even some plans for a set of Bongo Drums. (That might date it to the 50's??) I had not thought about the fact that it was not intended for rough blanks but I do think you are correct. There is mention about gluing up blanks, sawing them round etc. It has a 3/4" spindle and the castings, while not very heavy do appear to be very strong.

As for the Banjo it was/is a point of concern for me too. I have been toying with building (welding) something stronger and with some height adjustment on it.That way I don't damage the original and I can do more with the lathe. I bought it use but I don't want to ruin it either or do an permanent modifications to the lathe.. I have no problem with someone that would take this and restore it to like new, I just hate to see one not used then.

After giving it some thought while writing this I guess I am going to have to change my plans for this lathe. I think I was so excited to get it that I did not really think this through and consider the limitations of the lathe.. But that is why I asked for advice too!

The manual recommends a 1/2 HP motor but I don't have one that size and I still love the thought of variable speed even it it is not original to the lathe. Coming to my senses makes the slower speeds less important if I start out with round and reasonably balanced blanks. I have a bandsaw so I can trim up my blanks before putting them on the lathe but I still love to do natural edge bowls and I think with some care that shouldn't be a problem as they are not all that much out of balance. I guess I will just have to start slow and see what it is capable of.

I assume no one will ban from the group if I mount a chuck on here? :-)

BTW I am looking for a Delta/Rockwell lathe (Big heavy one, like the

46-450) with the variable speed control that I can add riser blocks too. So I can do an serious chainsawed, out of balance blocks on that lathe, once I find one.

Anxious for you input!

Reply to
Kudzu

Sadly, I believe I can recall advertisements for the J-Line (will you believe I learned to read very early?) in Popular Mechanics and similar publications. Fifties is the time frame. Perhaps if you checked an index you'd find something like a review.

Reply to
George

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