Problem using Record Power SC4 chuck with Nova DVR lathe

[Tim Pettigrew]

I have purchased a Record Power SC4 chuck with the correct insert to fit the spindle on my Nova DVR lathe (Record Power ID: 62132.  Thread Adaptor 1-1/4" x 8 TPI UNS-RH).

I have a strange problem as the insert jams solidly after about a quarter turn when screwing onto the lathe spindle. However if I remove the insert from the SC4 chuck and reverse it, it screws smoothly and fully onto the spindle perfectly.

I have several Nova chucks as well as a VersaChuck (all with the same spec thread to fit the spindle) and have no problems at all fitting these to the DVR spindle.
I'm totally at a loss to find the cause of this and wondered if anyone else has come across a similar problem?  I've raised the isue with the support people at Record Power and await their response.

Any advice gratefully received.

Tim

[Paul Hannaby]

It sounds like damage at the end of the thread

[Bill21]

It sounds like damage at the end of the thread

That was my first thought. Or possibly the thread has not been fully cut along the length of the insert?

[Tim Pettigrew]

I purchased the insert from Stiles and Bates and I am most grateful to Dave who has taken immediate action. He also (like Paul and Bill) thinks it's a damaged end of thread and is sending me an SC4 insert which he used on his own Nova DVR lathe before he sold it.  This is scheduled for delivery tomorrow and I am hopeful it will solve the problem.

[julcle]

Hi Tim, Yes Dave at S&B is very good and I am sure he will sort it for you. Can you just confirm from what you say about reversing the insert, Does the 1 1/4" x 8 thread go right the way through the insert then ?  It's just out of curiosity as mine never have.

[Tim Pettigrew]

Hi Tim, Yes Dave at S&B is very good and I am sure he will sort it for you. Can you just confirm from what you say about reversing the insert, Does the 1 1/4" x 8 thread go right the way through the insert then ?  It's just out of curiosity as mine never have.

No problem Julian, looking at the insert removed from the SC4 chuck and examining the inside.  At the front (the bit that's normally presented to the lathe headstock spindle) there is about 10mm which is unthreaded.  The thread then commences, and yes, it continues un-interruped to the back extremity of the insert.  So the problem I have is that the insert, when presented normally (front first) to the spindle, will not screw fully on to it but jams after about half a turn.   If I then remove it from the spindle, reverse it, and present the rear of the insert to the spindle (which obviously can only be done when removed from the chuck), it screws onto the spindle perfectly.

I purchased the insert from Stiles and Bates and I am most grateful to Dave who has taken immediate action. He also (like Paul and Bill) thinks it's a damaged end of thread and is sending me an SC4 insert which he used on his own Nova DVR lathe before he sold it.  This is scheduled for delivery tomorrow and I am hopeful it will solve the problem.

Here's an update to the above: Unfortunately there was a slight misunderstanding and Dave sent me a Nova chuck insert which although screws on my DVR lathe spindle perfectly, does not fit the Record Power SC4 chuck. 

I have now also raised the problem with Record who are sending me a replacement SC4 insert,  pre-tested to fit the Nova DVR lathe.

I'll post an update when I have received this.

Tim

[Richard_C]

Im sure you have tried the obvious, but the obvious sometimes escapes us.  I while back I convinced myself that my lathe was 'broken' and did all the usual supply checks only to find after 30 minutes that I had put a dust extractor tube down on top of the emergency stop button.   

The SC4 insert has a grub screw to lock it in for reversing.  The screw hole is near the 'back end'.  It is supplied with a little leather pad for non RP spindles, those where it might contact the thread, on an RP one it sits behind the threads.  It's just where it might stop you putting it on after 1/2 turn.

My experience is that the grub screw has to be backed almost all the way out.  If the main thread looks OK could it be the hard to see conical end of the grub screw protrusing a tiny bit, or the leather washer in there somewhere, or a badly cut grub screw thread leaving a ridge on the main thread?

[Bill21]

Another thought has occurred to me. The unthreaded part is the register,  and perhaps it’s been machined a little under size?

[Tim Pettigrew]

Im sure you have tried the obvious, but the obvious sometimes escapes us.  I while back I convinced myself that my lathe was 'broken' and did all the usual supply checks only to find after 30 minutes that I had put a dust extractor tube down on top of the emergency stop button.   

The SC4 insert has a grub screw to lock it in for reversing.  The screw hole is near the 'back end'.  It is supplied with a little leather pad for non RP spindles, those where it might contact the thread, on an RP one it sits behind the threads.  It's just where it might stop you putting it on after 1/2 turn.

My experience is that the grub screw has to be backed almost all the way out.  If the main thread looks OK could it be the hard to see conical end of the grub screw protrusing a tiny bit, or the leather washer in there somewhere, or a badly cut grub screw thread leaving a ridge on the main thread?

Thanks for that, Yes I've completely removed the grub screw so elinated from the equation.

[Tim Pettigrew]

Another thought has occurred to me. The unthreaded part is the register,  and perhaps it’s been machined a little under size?

That's exactly what I thought but checking with digital vernier callipers has eliminated that problem.  Also compared with the insert register of the Versa Chuck as well as other Nova inserts (which all work as designed with the headstock spindle).

The other possibility is a fractional mis-match between the alignment of the unthreaded  register and the thread itself.  This would certainly explain why the insert screws on OK when reversed.

I hope that I receive the "tested" Record replacement tomorrow.

[Tim Pettigrew]

PROBLEM SOLVED!
I was really puzzled as to why the SC4 insert screwed on to the spindle when reversed but not the right way round. 

I tried it in reverse again and suddenly noticed that it was binding and almost but not completely fully screwing home on the DVR spindle by about 1 turn.  So as there was no risk of cross-threading, I tried applying some moderate force to successfully screw it fully home onto the spindle and then repeatedly unscrewed and fully screwed it on again which eased the binding considerably.

I then turned the insert round the other (correct) way and, lo and behold, found that at last it would screw fully onto the DVR spindle albeit a little stiffly during the first turn. I then attached the insert to the SC4 chuck and was also able to screw it fully onto the DVR spindle at last. This was fine and there is no detectable run-out.

There must have been a roughness in the first part of the Record Power 8tpi thread on the insert which caused the problem, and screwing it fully on the opposite way, ironed it out so to speak.

So as far as I'm concerned I'm happy as I now have a usable SC4 chuck which will be very useful. 

Thanks to everyone who responded to this post.

Tim

[Bill21]

Glad you’ve got it sorted. 

[crazylegs]

odd I had this also. I sent it back to record and got another adapter. It was better but still is a pain to get on. They need to check their tooling .