Lathe stops when it's not supposed to

[Tiger]

Dear all,

I have the Hare and Forbes 900 b/w centres woodlathe. One very annoying feature about it is that when spindle turning it stops when you apply any sort of pressure onto it with a woodturning tool. Increasing the speed helps for a while but then it still stops unless I use reduced pressure and even then it will stop sometimes. I am sure there's an easy fix but what is it? Tailstock is done up as tight as it will go. The tailstock centre is also done up tight.

[Ian007]

what are you using in the head stock for the drive?Spur drive?

[Tiger]

Yes it's a spur drive.

[Utuk_Xul]

What do you mean stops? Do you mean the motor stops or the drive spur looses it's "bite" and the piece stops spinning but the drive spur is still spinning?

How do you mount your pieces? Really you shouldn't OVER tighten the tailstock. It will put undue pressure on the bearings I've been told. You should mark the center on your blank on both ends then with a piece of wood or wooden mallet tap the tail center into the blank on one end and then do the same with the drive spur on the other end. Put the tail center and drive spur back on the lathe and mount the blank on the lathe with the tail center and drive spur in the indentations you just made. Hand tighten till secure. Make sure you get a deep bite with the drive spur otherwise when you go to cut the drive spur will tear the wood and continue to spin while your blank stops.

[barnsey]

Having owned a H&F MC900 I'm a bit confused about your statement that the lathe stops.

What sort of mounting are you doing;
Timber
Diameter
Length
Mounting Method ( how are you mounting between centres - both ends)

Other than that my observation is that you probably need to drive the drive center home with a little more persuasion. If it's really hard wood cutting a lead in with the band saw or a tenon saw is necessary. In any event I always seat the drive dog home with a mallet off the lathe first.

FWIW

[Tiger]

Barnsey,

The wood I was turning was about 70 by 70 Redgum, it was about 200 long. I do hammer the drive centre with a mallet before I put it into the headstock.
Can you explain what you mean by a "lead in" and how that is cut?

[Bodgy]

If your lathe is belt driven like mine, then it may be the pulleys slipping on the belt - like the fanbelt slipping in a car. If so, tighten the adjustor for more belt tension and a bit of talc on the belt will fix it.

[barnsey]

Barnsey,

The wood I was turning was about 70 by 70 Redgum, it was about 200 long. I do hammer the drive centre with a mallet before I put it into the headstock.
Can you explain what you mean by a "lead in" and how that is cut?

Ok Tiger,

Redgum is often as hard as concrete and hammering the drive is a bit like trying to drive a nail in it. :eek:

Take to the drive end of the timber and once you are satisfied you have a center take the tenon saw and make a cut across the blank about 3-4mm deep. Then at right angles to that make another such cut. This will give the spur drive a lead in to get a solid grip (I'm assuming you are using a drive with 4 spurs here, if only two then the second cut is unnecessary.) Now when doing this just make sure that the drive seats well, the center may require a little easing with an awl just to make sure the point penetrates the concrete as well.

Turning the hard timbers we have here demands light cuts. It's good practice to take the corners off a square blank with the band saw, planer or hand plane if you must to reduce the loads when you are roughing to round.

Hope that helps.

Jamie

[BrianR]

Sounds like a loose belt to me.

[hughie]

Hi, I am little confused as well as I also own a Hare & Forbes lathe.[WL20]
Its belt driven with a variable speed drive -- reeves type. eg two pulleys that change diameter in order to change ratios and this effects the speed.
I suspect that your belt is worn, its 0-625, O being cross section type and 625 being the length.
When I bougth mine the motor was loose and out of line as with the variable speed pulleys, this caused some advanced wear and consequently I have changed the belt. I put a A-670 belt and packed the motor out with a block of hard wood. I am using the 670's cos I had em on hand and they are doing fine although the guard no longer fits.
regards Hughie

[barnsey]

Okay if the mounting of the timber is no longer a problem, then belt wear/slippage may be the thing however these variable speed mechanisms are usually very accommodating in that situation.

If you find that there is a lot of dust and gunk in the drive mechanisms this may be stopping the split V's from moving freely and placing tension on the belt. You need to clean it - instructions in the manual. If you've still got slippage then replace the belt. After that you perhaps need to check the alignment of the spindles parallel to each other.

If the unit is under warranty , talk to H&F - I found them quite prepared to help and stand by their product even after warranty.

[Tiger]

I have another issue with the Hare and Forbes 900 b/w centres. As some of you have suggested, perhaps there is dirt buildup on shafts etc. I took off the cover and cleaned what I could, I wouldn't say it was real dirty, but it made little difference to the lathe. I may not have mentioned that sometimes when I turn on the lathe that the lathe does not turn, it makes a quiet noise (like it's about to start) and then when I spin the handwheel gently it then goes into action. This has become more prevalent and is really giving me the *****. I may have to spin the handwheel 20 or 30 times over a 2 hour period. It doesn't occur everytime I stop perhaps every second time. As if I don't have enough to worry about with learning to sharpen woodturning tools and making sure I don't have too many catches with the skew chisel, I need to worry about the poor quality machine that I've bought. I've had a look at the belt. It is only slightly frayed but there seems to be enough tension there for it to work. Can you tell by looking at the belt that it's gone? How do you increase tension on the belt, what do you adjust? How do you take the belt off? There is nothing in the booklet that came with the machine on these questions, it is useless. Judging from some of the threads I have seen on lathes, my questions may seem basic to some forum members, but I am no engineer, could you please explain in simple terms what I have to do. I am loathe to try and take it apart as I would be guessing and could render the whole bloody thing useless. I would really appreciate some help here.

[Cliff Rogers]

Here's something to try... next time it needs a hand start, try spinning it the wrong way & see if it runs backwards.

If it does, the problem is with the start winding.
I could be the switch if it switch operated or a crook start cap if it has a capacitive coupling to the start winding.

WARNING! Don't spin it backwards if you have a right hand thread chuck on it that doesn't have alocking device, it may come undone.

[JDarvall]

yeh, what cliff says. Say its just the capacitor. Which is good news if it is. Quite easy to fix yourself. Just replace it. Often they are just in those bulgy cases on the outside of the motor.

Stating the obvious, but, pull the cord out of the wall before doing it. I'm not an electrician, but, thats most of what you have to really worry about, with basic electrical work.

Before I touch anything electrical must get in the habbit of ask oneself " is it on " ....cause, sometimes when your troubleshooting a problem, you may have put it back on and forgotten, and in your excitement in finally realising the problem (yippee!) you dash to fix it and ......zzzzapp !

[Tiger]

Cliff and Apricot,

Tried to turn it in reverse, the mere touch is enough to get it to turn and it turns in the right direction so I guess we could rule out electrical problems?

Really in a quandary here, Help!

[Bodgy]

Tiger

The symptoms your lathe is displaying is exactly the same as my bench drill and my lathe. Both need a helping hand to start spinning. There was a previous thread on this issue, a search on 'runs backwards' should find it. As I remember the verdict was a buggered capacitor, as advised in several above responses. These are cheap and easy to replace provided they are readily accessible. Also any electrician or appliance serviceman can check the cap in place.

Only thing that puzzles me is that the cap should not effect the lathe's performance once running.

Did you solve your earlier issue of the thing not having sufficient torque when turning?

[Tiger]

Bodgy,

My lathe doesn't spin backwards so I have ruled out the capacitor. I have looked at many of the threads here and actually came across one of yours which helps a little. I tried the talcum powder trick on the belt. It seems to have helped, but the lathe will still not start at times and if I stop the lathe while it's in a high speed say 1500 + , then it will not start unless I give it a spin. Makes me think it could well be the belt, although it doesn't look in bad shape and I can't see any slippage when I run the lathe without the sheet metal cover.

There are no instructions though on how to take the belt of the pulleys. Do you use circlip pliers, removes spring, then allen key....

The torque problem isn't as noticeable with timber other than redgum, but this start up problem has been consuming more of my time now.

[Bodgy]

Tiger

I didn't make myself clear, sorry. My spinning backwards probelm is caused by corrosion in the windings, not the capacitor, due to a very damp shed and neglect (since fixed). I mentioned the search on backward spin cause it also covers the capacitor problem.

The not starting problem is the capacitor. As I understand it the cap stores up power, jumps up the amps/wattage or whatever and then squirts it out at start-up when needed to overcome the inertia. NB This is from someone who just scraped Physics at school.

I'm a little unclear too. When you say it fails to start, does this mean the motor dont go around and just sort of hums threateningly, or do you mean the motor spins but not the spindle?

I the motor turns OK at start up and the problem is with the spindle then ignore the above, sorry. It must be the belt or pulleys. Can't help as my Chinese cheapo aint as flash as yours, its a manual change speed by moving the belt to different pulleys. One screw is all that locks the drive shaft.

[Utuk_Xul]

Not familiar with this lathe, but if it has a reeves drive then try to always put it on the slowest speed before you turn it off. The motor has quite a time trying to start when on a higher speed.

[Ashore]

Tiger
The starting problem could well be the capacitor , or the starting load is just too great for the motor to overcome
This could be any number of thinds from belt alignment ( unlikely ) to a bearing needing re packing ( again I think unlikely ) to a bush needing oiling or lubricating
This may be adding to your promlem, Does the lathe have greese nipples or oil points and when was the last time you did a lub job on the lathe , including the tailstock http://www.woodworkforums.ubeaut.com.au/images/icons/icon5.gif


The trouble with life is there's no background music.



Ashore

[Cliff Rogers]

.... As I understand it the cap stores up power, jumps up the amps/wattage or whatever and then squirts it out at start-up when needed to overcome the inertia. NB This is from someone who just scraped Physics at school......

Not really....some AC theory required here... there is a second winding that is physically placed out of phase with the first & the capacitor changes the phase angle of the incoming AC. As well as helping start the motor it ensures that the motor always runs the correct way.

The belt is not too tight is it?

[Bodgy]

Not really....some AC theory required here... there is a second winding that is physically placed out of phase with the first & the capacitor changes the phase angle of the incoming AC. As well as helping start the motor it ensures that the motor always runs the correct way.

The belt is not too tight is it?

Cliff, can you be a bit more explicit? The Capacitor must store power somehow, or else how does it give you that huge belt when you touch the contacts when the powers off to the machine? Sorry, don't understand.

Sorry Tiger, hijack underway.

[Cliff Rogers]

Long story, involves understanding of AC & DC circuit theroy.

The Cap will store a DC Voltage (that's what bites you) but passes AC Current 90° (approx) out of phase (leading).

It won't store enough to kick start a motor.
If it relied on that & you didn't use your motor for a while, when you went to use it, your cap would be flat. :(

The tricky bugas that thought this up rely on the change of phase angle caused by the cap & the start winding being placed out of phase with the run winding to make it always start & run in the same direction.
Only applies to AC motors.

The rest is beyond the scope of my typing I'm afraid, if you need to know more than that, you'll have to google it. :)

[Bodgy]

Thanks Cliff, thats enough!

[JDarvall]

Cliff and Apricot,

Tried to turn it in reverse, the mere touch is enough to get it to turn and it turns in the right direction so I guess we could rule out electrical problems?

Really in a quandary here, Help!

I'm no expert. But I do know there are many types of motors out there.

You can get single speed non-reversing circuits. Centrifugal starts etc.

So, IMO, just because its not going in reverse doesn't mean its not the capacitor.

The most frequent problem I've come accross in all the motors I've fixed is the capacitor. From mixmasters to washing machines. So, I'm still betting on it being a capacitor problem. I'd try and replace the capacitor first to at least rule that out.

Goodluck.

[seanr]

I've never ownesd a lathe , but a bit of common sense here. If its pretty new take it back get your money and buy another (at least GMC gives you a 2yr waranty). If its new dont even try to fix it get your $ back ...

Like someone else wrote if its in too high a gear like trying to start a car off the mark up hill in 5th.

GO GMC!!!

[Mike Jefferys.]

Assuming you have eliminated the obvious possibilities of the drive chain, loose pulley, slipping belt and if the syptom is that the motor humms but doesn't turn when you switch on and that flicking the shaft by hand gets it going then its almost cetainly a problem with the start winding. Assuming you have a single phase motor i.e a standard 3 pin 10 amp plug - most of us do - then you will have a motor with a start winding and a running winding. The problem is most likely that the start winding is either fried, or the start winding capacitor is on the fritz ( the most common diagnosis - it is changeable and usually sits outside the motor housing) or the mechanically operated internal centrifugal switch is not functioning. This switch sits around the motor shaft with spring loaded weights and clicks in and engages the start winding when the motor slows right down or stops and helps to get the motor started and clicks out and transfers the work to the main motor winding when at speed. By flick starting by hand you are in effect doing what the start winding does. If the motors centrigfugal switch clicks in when you put a heavy load on the motor and then clicks out when you remove the load then you are at least blessed with an underpowered setup or at worst a flakey motor.
For the technically minded 3 phase motors have no start winding and no centrifugal switch so are inherently simpler in design and usually therefore horse for horse a bit cheaper and more efficient. Three phase is generally desirable in terms of efficiency and cost of gear but bear in mind you have a greater potential electrical hazard because in polyphase installations the phase to phase voltage is about 415 whereas a single phase environment is a 230 to 240 volt maximum. A 3 phase belt is frequently lethal which is not to suggest a 240 volt one is pleasant either.
In summary if you have eliminated the mechanical causes it is lilely to be electrical.
Mike Jefferys

[JDarvall]

Isn't the easy way to determine if its electrical or not, to just isolate the motor temporarily......I mean, just take the belt off, start the motor. Does it start properly without it connected to the spindle ? .....yes ? ....well, is it providing any torque ? To check this I'd just put on a thick glove, like a welding glove or the like, and just cup the motors shaft or pully in my hand. Tightening my grip to see if I can stop the motor in my hand. If it wavers, or stops. well, its definetly electrical. right ? Shouldn't be able to do that with a healthy motor.

[Tiger]

First of all a huge thanks for your efforts in trying to help me diagnose the problems with my lathe. Yesterday, I'd had enough and so I took the capacitor cover off the motor. Had a close look at it and tested it with the multimeter, no reading. Rang the place where I bought it from, they said it's probably the capacitor, we don't have any in stock:( , they cost around $24, if you pay freight, that's another $12 and you can have it tomorrow, otherwise 2 weeks. On the capacitor, were the specifications. I rang Middy's, they don't carry these parts. Went to Actrol (air conditioning parts) and they had 1 left at $16 (and it was a much better version imported from Italy) but it was a different design to the chinese job that was in mine. Asked the salesmen there to test his capacitor and that didn't register a reading either :confused:. It took a little bit of work and modification but I was able to attach it to the lathe. Then I tested it, it worked, stopped it and re-tested again, must have stopped and started it 20 times and it worked every time. The lathe seemed to even run better with the new capacitor. Spurred on by this, I then had a look at the tailstock which had been bugging me. It seems that the nut underneath the ways has to be tightened in the right spot before it will hold efficiently. Managed to fix that too.

Then the drive dog. With a file, I carefully sharpened each of the 4 spurs, then tested it on redgum. It was better but I wasn't satisfied. I then sharpened some more and the spurs were very sharp. Tested the redgum and it stuck, even a fairly big chunk (about 400 long and 80 in diameter), no lathe stopping now. The roughing gouge is still a problem but I have convinced that the steel is not as good as the other lathe tools and that is why it is causing problems but I'm happy with the lathe for the moment. :)

[Cliff Rogers]

...tested it with the multimeter, no reading....to test his capacitor and that didn't register a reading either :confused:. ...

Beauty.
Don't pay too much attention to the reading you get from a multimeter on a cap, particularly if it is a digital meter on the ohms range.
You will only see a steady reading if it is shorted out.
If you use a moving coil meter on the ohms range, you should see the needle flick up & drop back & then when you reverse the leads, it will do it again.
You can get fancy meters for testing caps but the best & cheapest way is to replace it with a known good one.

OK, make the chips fly. :D

[Ashore]

Glad you got a good result tiger http://www.woodworkforums.ubeaut.com.au/images/icons/icon7.gif
When you test a capacitor you need a specialised meter that reads farads
A multi meter if you test in resistance mode will show the ohme reading slowly raising, this hapens as the battery from the multi meter slowly puts a charge into the capicator but wont ever give you a reading that will tell you if the capacitor is gone or not http://www.woodworkforums.ubeaut.com.au/images/icons/icon6.gif



The trouble with life is there's no background music.


Ashore

[Tiger]

Thanks, Cliff and Ashore for the electrical advice. As you can see my knowledge of electrics is limited :o . I had hoped that there was a simple way of testing capacitors with a multimeter, but it looks like there ain't so replacement is the way to go.

[JDarvall]

You fixed it ! ....good to hear it.

Satisfying to fix yourself I reakon. Avoids been ripped off by a pro too. I take it you didn't zap yourself, like I nearly did once. :D

You can often take capacitors off old abandoned motors as well. Saves you a few dollars. OR just buy a new one :D

[Tiger]

Apricot,

Didn't think of taking it off an old motor, by the way how did you nearly zap yourself?

[JDarvall]

Apricot,

Didn't think of taking it off an old motor, by the way how did you nearly zap yourself?

Actually, I did zap myself. Spose, I mean't 'nearly kill' myself.

An embarrising story. When I first started messing with motors I got a little too enthusiastic. I'm the sort of bloke who likes taking things apart you see, to try and work out whats what. Being 19 didn't help either. I replaced one part, plugged the cord back in, found that I hadn't fixed it, sat and thought about it for a while.

Then suddenly realised how to fix it. Got real excited,,,as you do,,,, jumped up to pull the crap part out, forgeting that the power was still on, touched one of the live wires, and Buzzzzzz,,,,,felt this rolling thunder like waves type feeling through my body. That sort of froze me for a little while, then just pulled off. I was a stuned mullet for a while. The waves I guess was the AC.

It was odd, because I didn't get any knee jerk reaction to just pull my finger off. Just sort of took it. Maybe I was subconciously enjoying it. :p

I don't know what sort of voltage hit me, but I can fairly say it wasn't at full 240v, cause I'm still here. Felt weird all day. BUT, it did fixed my back !.....So, it wasn't too bad. But I wouldn't recommend it. :D

They say playing with electricity is for the experts. Sure, probably. But, IMO for simple wiring, the only real scare is stopping yourself from doing stupid things like this. The rest is quite straight forward. I mean, that was really bloody stupid. Like crossing the road without looking for cars.

:D oh dear.

[Tiger]

Apricot,

Think we've all been there. Sometimes you get so enthusiastic you forget the little things like turning the power off.

Not 100% sure about this but in England you are allowed to do a lot of electrical work yourself.

[hughie]

Hi Tiger,
I have a 1100 which is virtually the same as your 900. One problem I have come across and its very annoying.
The problem I have is that it chews out belts at a alarming rate - 2nd belt in two months - If your lathe is sliping or stopping, I suspect its because of the worn belt, on my one, as soon as some fraying is evident it starts slipping and continues until all the drive is lost -- bugger!
I orginally thought it was because of miss alignment of the motor pulley etc. So I spent time realigning and so on. Last night the belt showed signs of fraying and belt slippage followed to the point where it was useless to continue.
Normally this type of vaiable speed is no where this rough on belts. I have had a look at it and it seems ok on the face of it, no rough or sharp edges to chop the belt out and the alignment is fine. If I find anything I will keep you posted.
Hughie

[Tiger]

Thanks, Hughie.

My belt looks a little frayed, buy it still seems to work ok. I tried one of Bodgy's recommendations about putting a bit of talc on the belt and that did seem to help a little.

I don't use the lathe all that often which is why I'm disappointed that it's given me a few problems. After seeing some 2nd hand lathes, I think I erred in buying the 900 from Hare and Forbes. My first purchase was the GMC lathe which necessitated changing pulleys manually so I upgraded to the 900 model but there isn't much difference in how they run. If I had my time again, I'doubt that I'd buy it. But please keep me updated on how it runs. Is it worthwhile trying a different brand belt?

[Utuk_Xul]

I've posted on here before about the belt fraying. Whether or not you feel a sharp face try taking some 600g or so sandpaper and run it across the inside of the pulley wheels a few times. Mine was terrible about fraying the belts until I took some sandpaper to the wheels. No visible wear on the belt now.

[hughie]

Tiger i have stripped it down and it has noticable wear across there reeves drive. A little more than I thought. I would go with the idea of giving a rub with sandpaper etc.it cant do too much damage
Me I going to fit an inverter and a 1hp 3 phase motor on it asap. As I suspect that the reeves drive in this case will chop out belts on a regular basis. For me I am doing fairly large bowls and it looks like its too much for the set up. But as soon as I get some fraying the drive starts to fail. Go easy on the talc as it will add slip if you get too much and it is a stone at the end of the day.
Have a good look at all the alignment of the whole set up and check if all the fastners are tight, none of mine were when I got it and the alignment was way out.
I changed my belt for an A section over the original O section. This could be some of my problem in so much as there could be a angle change on the belt.
But give a new blet a go as its probably well on the way to being stuffed if you have had this much trouble already. Most likely when you get all the alignment sorted out etc It will settle down.
cya Hughie


My belt looks a little frayed, buy it still seems to work ok. I tried one of Bodgy's recommendations about putting a bit of talc on the belt and that did seem to help a little.