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Scott
1st September 2011, 07:38 PM
Dear Brains-trust,

I'm frustrated and annoyed! Since I bought my Nova 1624/44 lathe I've had issues with the headstock pulley moving along the shaft under heavy load. As a consequence the main issue is that the pulley belt has broken 5 times. At $29 a pop. FYI, the belt breaks before I know what's happening or alternatively the belt wears easily.

The pulley slides along the shaft and is kept in place with a 6mm key. To hold the pulley on the shaft a grub screw is used to hold the key down on the shaft. I've attached a few photos for your reference.

I've dismantled the lathe a couple of times and I always ensure the pulleys are aligned before I start a session. The manual is no help.

So what should I do? Red loctite on the key and grub screw? And if loctite is recommended, will I be able to unlock the grub screw and/or key at a later date?

Thanks in advance, Scott.

jefferson
1st September 2011, 07:54 PM
Scott,

Some of the Nova owners will hopefully have an answer for you.

All I can say is that you wouldn't have had the same problems with a Vicmarc. I know, double the cost etc etc, but a lot less anguish.

As they say, you get what you pay for...... :rolleyes::rolleyes::rolleyes:

Scott
1st September 2011, 08:12 PM
Thanks Jefferson, at the time my budget was limited but yes, a Vicmarc weighed heavily on my mind. One day.

Ed Reiss
1st September 2011, 10:10 PM
Hey SJT,

Yes...Loctite will hold the grub screw in place. I had a 1500 and applied Loctite when bought new and had no problem with the grub screw loosening up.

Yes...you will be able to loosen it if need to.

Loctite on the key? NO

Good luck!

Big Shed
1st September 2011, 10:16 PM
Looking at that key, I'd be considering replacing that, it looks knocked about in the photo.

Scott
1st September 2011, 10:22 PM
Thanks Ed and Big,

Yeah, I bought the lathe 2nd hand and wondered about the pulley. I just went out to the (small) shed and looked at the key. Yep, it's a bit battle scarred therefore I'll replace. I'll add some loctite to to the grub when it is replaced.

Avery
1st September 2011, 10:25 PM
Is there room for a second grub screw to lock in the first?

Scott
1st September 2011, 10:28 PM
Is there room for a second grub screw to lock in the first?

Easily, probably one and a half.

Avery
1st September 2011, 11:25 PM
Easily, probably one and a half.


One and a half is probably half too much.

A second screw will stop the first coming loose and may solve your problem. Two grub screws are pretty common motor pulleys.

Scott
1st September 2011, 11:45 PM
Thank you Avery, will give that a go as well.

hughie
2nd September 2011, 01:03 AM
Is there room for a second grub screw to lock in the first?

....failing that try drilling a second grub screw at 90' to the one on the key.

My concern is what is causing the grub screw to come loose in the first place.:?

Check the clearance on the pulley when assembled on the shaft with the key in place. There should be very little movement, in fact it should go together with a light tapping of a soft headed hammer. If the fit of the pulley on to the shaft is sloppy or if the key way is worn then your getting movement as it is used and the grub screw will work loose.
You can use bearing lock on the shaft as you assemble the pulley etc and like loctite etc it will loosen with heat around 60-70C should be plenty. So it wont be a problem to remove at a later stage.

The Loctite corporation make the screw lock 242, 262 etc as well as the bearing lock. If you do plan to use this method dont go for the max strength try a medium strength. Locking the pulley and grub respectively should not need any more than a medium strength locking.

good luck :2tsup:

Skew ChiDAMN!!
2nd September 2011, 01:10 AM
:whs:

For a grub to constantly work loose, there has to be a reason. Either vibration or movement between the mating pieces.

Loctite or a 2nd grub screw will eliminate this particular problem if it's cause by vibration... but there's always the possibility that the vibration will show as other problems.

If it's loose mating surfaces, then such a fix will only be temporary, as the contact surfaces - end of the grub and the contact point on the shaft - will suffer undue wear, until it slips again.

Your best bet is to find the real problem, the "why" and fix that first. :;

Drillit
2nd September 2011, 10:15 AM
Hi SJT,
As I am looking at buying a Technatool right now, I would appreciate any feedback on developments, as I am sure many others would also. Good luck - IMHO Hughie's suggestion seems to have a lot of merit. Drillit.

Scott
2nd September 2011, 10:40 AM
Hi SJT,
As I am looking at buying a Technatool right now, I would appreciate any feedback on developments, as I am sure many others would also. Good luck - IMHO Hughie's suggestion seems to have a lot of merit. Drillit.

Will do! I think, in hindsight, I should of saved a little extra for the DVR. Whilst changing belt speed manually isn't a problem (takes seconds), a variable speed lathe would of been better. This would eliminate the need to align pulleys. And as Jefferson has suggested, a good quality Lathe should eliminate these problems all together.

Skew has a good point, find the source. I'm going to replace most parts and loctite the grub screw however I think the alignment of the motor pulley is crucial. To loosen the belt to change speed, the motor and motor pulley are set up on a cam which you push/pull. The issue with this is that the motor pulley can go out of alignment with the headstock pulley. When this occurs the belt then applies sideways pressure to the headstock pulley. This is what I *think* loosens the grub screw. All the bearings and motor are fine with no vibration at all. I can't test my fix until Monday when I get the belt from CBC. When I do I'll take photos and describe my fix in more detail.

-Scott.

Scott
2nd September 2011, 10:41 AM
Just to add, I have contacted/emailed Teknatool and haven't had a reply. I think I'll point them to this thread, might jolt them into action.

wheelinround
2nd September 2011, 10:50 AM
Scott how tight are you making the belt they are supposed to be just enough pressure on them to run the pulley??

Are the bearings free when the belts not on?

Yes there are or have been issues with the key way and grub screw from a couple of fellows i know not on here fixes as have been stated above.

Forgetting the Indexer is on does not help :B

Scott
2nd September 2011, 10:58 AM
Scott how tight are you making the belt they are supposed to be just enough pressure on them to run the pulley??

Yep, just *enough*, made that mistake the first time.


Are the bearings free when the belts not on?

Bearings are fine.


Yes there are or have been issues with the key way and grub screw from a couple of fellows i know not on here fixes as have been stated above.

About to head out the door to get some loctite :)


Forgetting the Indexer is on does not help :B Errr, i do that ALL the time, must reprogram brain. :B

Paul39
2nd September 2011, 02:58 PM
Errr, i do that ALL the time, must reprogram brain. :B

Especially if one does not turn every day.

Make a check list of steps to do before starting lathe & stick up where visible. Do them in order each time. After 10s or hundreds of times it becomes habit.

Do a search of "turning safety" to help with the list. Having a block of timber come out of the lathe because you didn't lock the tailstock, or starting the lathe at too high a speed with an unbalanced blank will make you a believer.

If airline pilots can do a check list every time before starting engines, so can we turners.

Avery
2nd September 2011, 03:06 PM
Make a check list of steps to do before starting lathe & stick up where visible. Do them in order each time. After 10s or hundreds of times it becomes habit.



That is really excellent advice for all of us - and not just for the lathe. It could apply equally as well to bandsaws, tablesaws etc. etc.

Thank you.

wheelinround
3rd September 2011, 11:14 AM
Yep, just *enough*, made that mistake the first time.



Bearings are fine.



About to head out the door to get some loctite :)

Errr, i do that ALL the time, must reprogram brain. :B

This is possibly whats causing the damage to pulleys and key way also will possibly be enlarging the hole on the index plate.

oldiephred
3rd September 2011, 11:31 AM
Not at all familiar with that make fo lathe but it looks like the spindle has an internal thread. Can you use a bolt and washer in that to prevent the pulley from working off until you can find the cause of the problem? Might save you a belt ot two and allow you to get on with turning.:?

issatree
4th September 2011, 12:46 PM
Hi sjt,
I'am wondering why all those Belts have broken.
Is it because of the Pulley slipping on the shaft.
Have you got your belt to tight, which I'am leaning toward.
Like I said in a previous thread, had my Lathe 21 yrs. V belt. Lathe sits on 3000 RPM. most times, & just the weight of Motor controls the Belt Tension.

Sorry sjt, didn't read page 2, as someone has already mentioned that. had to edit this.

Scott
4th September 2011, 01:09 PM
Thanks all for your advice. I've spent most of the weekend pulling apart the lathe and reassembling. Issatree is spot on, I had the belt too tight. Secondly the belt was/is slipping over the grooves which had spread. This was fixed by purchasing a new headstock pulley. The index holes were worn as well, this would of been caused by turning on the lathe when the pin was engaged. I would of had to replace the pulley anyway as the previous owner had given it a bash to get it off the shaft. Thankfully the shaft was ok. Lastly I added some loctite to the grub screw and inserted another over the top. This pulley ain't moving now. I've also greased and oiled everything and waxed the rails.

As a result the lathe is humming along beautifully, thanks to the combined responses of everyone here. Thanks once again.