Thread: Identifying a lathe.

Gday Folks,

I've got a small problem that I'm hoping someone can help me with. Sam and I, well Sam mostly with me looking on with what was hoped to be an intelligent expression, wired up the VSD and with no potentiometer it would run up to 100htz but with the 10kw pot installed it would only run to 70htz. So it was decided that maybe if the 10kw pot was changed for a 25kw pot then we would get 100htz. So with trusty soldering iron in hand I changed the pots, rang Sam and fired the VSD up. Hit run and it still wont run past 70htz.

It was then decided that Sam would ask on forums he frequents and I would ask you guys here.

So my question is what could be the problem and how do we fix it?

Thanks in advance,

Ross.

Hi Folks,

Sam came over last night and worked some more of his magic on the lathe. When he left it was connected to power via the VSD and speed selected through the pot. We did strike one problem though, the motor being alot bigger physically meant that the plate holding it fowled on the bottom motor support so without full travel the belt ended up be way too long.

We did fire the beasty up with the belt on the big jack pulley and big drive pulley and while it all ran nicely it did show that I need to pull the jack shaft out and see whats going on with the bearing there.

This afternoon I went out to the shed, sat down in front of the lathe and removed the bottom support to see how much more travel I'd get and whether it would be enough to tighten the belt.

IT DID IT DID so now I have a 4 speed lathe via the pulleys and variable speed to boot.

I'd never considered just how slow 50rpm on a lathe really was and how much torque this set up was going to have. I tried three times on the lowest speed with leather gloves on to slow or stop the lathe by grabbing the hand wheel, not a hope in hell of achieving that.

It will still only go from 10hz to 70hz but for now its certainly useable which is what I was after for now. I'll give Sam some time off then I'll bribe him with some more food, he tells me eye fillet steak goes along way, to get him to set up the forward/reverse, the rev counter and emergency stop button then all it needs will be a coat of paint to finish it.

I'll post some pics when it all finished.

Oh, almost forgot, spoke to Rod from Omega the other day. He told me they started making these lathes between 20 and 25 years ago, not the 30+ I'd been told previously. The first two or three werent even numbered then they started numbering them on the stand at the end of the bed, have to remember to check that. After that they had the Omega name made up as an aluminium badge that was fixed on that same stand and they still have some of the badges in stock. He also asked if I would send him some pics of the lathe as I got it, WIP and the finished product.

Anyway, thats all from me for now.

A big thanks to Sam for all his work,

Ross.

Ross,

If you have a constant torque VFD you will not be able to stall it. Below are the three types:

• Variable torque, such as in centrifugal fan, pump and blower applications
• Constant torque, such as in conveyor and displacement pump applications
• Constant power, such as in machine tool and traction applications.

More than you ever wanted to know about VFDs:

http://en.wikipedia.org/wiki/Variable-frequency_drive

There should be a forward - reverse switch on your VFD control box. If you got a new one with instructions it should be listed.

I found that the printed instructions that came with my TECO VFD were translated from Chinese by an Indian but the mini CD had more and understandable instructions.

Originally Posted by Paul39

I found that the printed instructions that came with my TECO VFD were translated from Chinese by an Indian but the mini CD had more and understandable instructions.

Paul, so you have not learnt to read and understand Chinglish yet? Get used to it, most of the stuff we get comes from over there, and the way your country is going, so will you guys. Saw a program on the telly recently, about a giant container ship built exclusively for Walmart, goes from China to L.A. full and back to China empty each trip.
rgds,
Crocy.

Crocy,

It is very hard to find anything here not made out of the country, mostly China.

Hey Paul, thanks for the link on the VFD's, havent finished reading but very interesting.

OK, after firing the beast up the other day the most prominent noise was coming from the jack shaft or its bearings so tonight I worked out how to extract the jack shaft to have a look at what is going on. Both bearings are noisy with one being decidedly crunchy and unfortunately the crunchy one appears to have worn a small groove in the jack shaft wear it was positioned.

In the image you can see just down from the top of the shaft where the bearing sat and the groove it has made.002 reworked.jpgNot exactly sure of what to do there or if I do nothing what the outcome will be, whether its possible to shim or if a new shaft is needed. Anyway, will get new bearings tomorrow and see what happens. Any thoughts will be appreciated.

Originally Posted by fozz

Hey Paul, thanks for the link on the VFD's, havent finished reading but very interesting.

OK, after firing the beast up the other day the most prominent noise was coming from the jack shaft or its bearings so tonight I worked out how to extract the jack shaft to have a look at what is going on. Both bearings are noisy with one being decidedly crunchy and unfortunately the crunchy one appears to have worn a small groove in the jack shaft wear it was positioned.

In the image you can see just down from the top of the shaft where the bearing sat and the groove it has made.002 reworked.jpgNot exactly sure of what to do there or if I do nothing what the outcome will be, whether its possible to shim or if a new shaft is needed. Anyway, will get new bearings tomorrow and see what happens. Any thoughts will be appreciated.

I am assuming there were roller or ball bearings on the ends of the shaft which fit into the arms of the mount, and the bearing locked up and rotated on the shaft and wore a groove. I would replace both bearings with pregreased sealed bearings, they will last for years.

If by removing the bearings and pulleys and putting them on in reversed position, the bearings on the ends fall on a good part of the shaft, that would work. An engineer shop could turn down the worn end and fit a bearing with a smaller inside diameter with the same outside diameter. Probably the simplest would be to take the shaft to an engineering supply place and see if they had a replacement on the shelf. If they only had a plain shaft, an engineer shop could cut the key slots.

If the small pulley and the step pulley are one piece or locked together, and have set screws to hold the key between the pulleys and shaft, a plain shaft with a flat ground for a longer set screw to bear upon would work.

If the small pulley and the step pulley are separate and both have set screws, a hole drilled in the shaft about 5 mm deep and a pointed set screw run into the hole would work. That set up would need to be checked from time to time, and if loosened some Loctite applied and tightened quite hard.

http://www.loctite.com/

Thanks for the info Paul. Changed the bearings this afternoon for new sealed bearings and was able to get the bearing onto a good section of the shaft then move the pulley over, tightened it down so the bearing cant move over to the worn section. Started the lathe up and it now purrs like a big cat, just need to attach the bottom mount for the motor and it should be all good.

Thanks to all of you who have helped and commented, its much appreciated.

Ross.

Good afternoon Folks,

Went down to Middy's late in the week to pick up 3 metres of 4 core 2.5mm flex to wire the motor up properly, fitted it Friday afternoon and as I was doing that I knocked one of the pot wires out of the vfd. I put it back where i thought it went but could then only get the motor to run to 40hz so figured I'd put it in the wrong place so undid the wire and left it. One thing I did notice after taking the vfd of the wall is that the terminals seem to be upside down in that you unscrew them and the holding plate doesnt come up but instead it goes toward the back of the terminal, the wire goes in there and then when tightened the plate comes back in toward the front of the terminal. I know I know, to you boffins its common place but to a novice like me in was very interesting to find that out.

Saturday comes around and I wanted an out board control panel like the one on the Oneway Lathes so out with the welder and angle grinder, some bits and pieces cut and welded together and ended up with an arm that holds the control and will swivel on a pivot from one end of the lathe to the other. Late in the afternoon a friend and his misses came over to see what I was up to. She took one look and fled for the shopping centre while he stayed and being a sparky although being off the tools for a long time found the whole thing of great interest. I explained what was going on and asked him if he would wire it up for me, one to get it up and running and two to save Sam the time for his own things. Sure he says have you got a manual for it? Handed him the manual and for the next hour he looked and read, mumbled a bit, looked and read some more then asked who wrote this &^$%&^%*&^(^$&^* stupid manual and have I got a wiring schematic for it?

I explained that was THE MANUAL and no I didn't have a schematic but hopefully there would be one on the net. He told me if he had a schematic it should take less than an hour to wire the whole thing so last night I did a search and found this


so this morning I got out into the shed and having the monkey see monkey thinking and figuring if wire A goes into terminal A it couldn't be too difficult to wire it myself. I did get the emergency stop wiring back to front but that was an easy fix. Had to ring Sam to work out how to get remote control to the out board panel, got that sorted so now the beast runs forward and reverse, is variable speed, and has a big red emergency stop switch.

The only thing it wont do is run past 70hz, the PD is set to 100hz so my question to you folks is where to look to see what could be causing this.

I'll post pics tonight of the arm and control panel so you can see wheres its up to.

Thanks again to all of you for your help, it really is appreciated.

Ross.

The only thing it wont do is run past 70hz, the PD is set to 100hz so my question to you folks is where to look to see what could be causing this.

70hz in top gear gives you what RPM? Unless you are doing pens or 5mm finials, I don't think it will matter much that you get the last bit of RPM out of the motor.

Controller at 50 HZ, motor makes 1400, same size pulley on motor and spindle, spindle is turning at 1400.

Controller at 70 HZ, motor & spindle make 1960, and you have a step pulley to make it faster.

My 350mm swing Hegner has 800, 1400, and two higher speeds. Bowls, I rough, finish turn, sand, and apply Tung oil at 800. On smaller bowls, I may finish turn at 1400. 350mm out of balance blanks are a bit spooky, but 800 is the minimum, and I have been too busy making turnings to do a variable speed set up or a countershaft.

Depending on how out of balance the split log is for a spindle, I'll start at 800 or 1400 and finish turn, sand and apply Tung oil at 1400.

The smallest I turn is about 30mm. I did try one step higher than 1400 once and that was too fast for my taste.

Hi Paul,

At the moment at 10hz the lowest speeds are,

59, 76, 186, 285

and at 70hz the speed are

415, 532, 1302, 1996

at 100hz they should be

593, 759, 1859, 2851

For my own knowledge I'd be interested in what could be the cause of the 70hz top considering that PD is set to 100hz

Fozz,

For my own knowledge I'd be interested in what could be the cause of the 70hz top considering that PD is set to 100hz

You might ask the question here:

http://www.practicalmachinist.com/vb...onverters-vfd/

I have belonged to Practical Machinist as long as the woodwork forum and have had no spam or bad things happen to my computer attributed to PM.

PM is for professionals and hobbyists that use medium to large machines. When you ask questions, give details about your VFD and motor used on a wood lathe.

See:

http://www.practicalmachinist.com/vb...elines-137724/

Hope you will get some help with your question.

Thanks Paul, appreciate the help!!!

As promised, a few pictures of the remote controls and the arm they are mounted on.003.jpg002.jpg005.jpg004.jpg Pic one, arm mounted to the underside of the bed, pic two, the arm and control panel with pot, stop forward and reverse and emergency stop, pic 3, the VFD and pic 4, where it sits on the wall. By the way, in pic 4 there is a collection of M2 tapers, warning, dont have them so close together, THEY BREED!!!!!!!