Thread: Nova 1624/44 Woes

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......

Thanks Jefferson, at the time my budget was limited but yes, a Vicmarc weighed heavily on my mind. One day.

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!

Looking at that key, I'd be considering replacing that, it looks knocked about in the photo.

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.

Is there room for a second grub screw to lock in the first?

Originally Posted by Avery

Is there room for a second grub screw to lock in the first?

Easily, probably one and a half.

Originally Posted by sjt

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.

Thank you Avery, will give that a go as well.

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

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.

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.

Originally Posted by Drillit

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.

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.