Do faceplate threads need to be fully seated?

Re: Do faceplate threads need to be fully seated?

Dennis in Southern Oregon

One reason that I can see is that if the faceplate does not fully seat, it will act like a tap and attempt to further extend the thread of the spindle and possibly raise burrs. As a practical matter, the homemade face plate material probably is much softer than the spindle material and probably would not produce much scarring. Completely aside from that, the nut/spindle thread clearance is rather large and it will be pure luck if there is no significant runout if the nut does not fully seat.

Re: Do faceplate threads need to be fully seated?

Chuck Engstrom

Hi David -- I think that the issue of faceplates not being fully seated on the spindle is that you are making your attachment between the faceplate thread and the spindle thread by just jamming the threads together, rather than having the flat faces of each come together neatly all around. I have no engineering training in this stuff but it seems to me that the proper way to fit threaded pieces together is to do so at their faces, rather than just jamming the nut, so to speak. You sometimes have trouble detaching the faceplate because you've jammed its thread on the spindle, and the rotation of the lathe just drives it on harder and harder.

I have a couple of chucks whose thread is too short to go over the full length of my spindle thread, so I made a very thick "washer" from 1/4" aluminum plate to go onto the spindle before the chuck. I didn't use ordinary washers since they are not always dead flat.

Perhaps we have a good engineer or machinist here who can shed more light on the issue of jamming threads as a manner of connection.

--Chuck

Re: Do faceplate threads need to be fully seated?

Doug Ladendorf

My first experience with this was at a class of my turning club on making a vacuum chuck. We used a nut epoxied into a wood mount with a segment of PVC. On the lathe it was made the nut mounted flush against the arbor and worked great. On my lathe however, it did not screw all the way on and had too much runout to use. From that and subsequent tests with faceplates that don't screw on all the way I now try to always get a firm connection rather than rely on the threads.

Doug

Re: Do faceplate threads need to be fully seated?

Sean Troy

I've had that issue in the past and the solution is to get some nylon spacers. They are made just for that reason and as to keep Chucks for getting stuck on the spindle. Always worked well for me. I've purchased from Craft Supplies, Woodcraft and Rockler in the past. Other's may have them as well. Just get the correct size for your spindle.

Re: Do faceplate threads need to be fully seated?

Barry Irby

I learned from the ones I had made several important things. Some lathes have things seat against the end of the spindle and some have them seat against a shoulder on the shaft. You should understand which way your lathe works and make sure the machinist that welds up the face plates understands as well.

Mine registers off the should on the shaft. The nuts I bought were "deep" enough to "bury" the entire shaft without the end of the shaft registering on the back side of the face plate. Once the nuts are welded on the machinist makes a similar shaft for his lathe, mounts the face plate and tuns the outer edge true and faces it off so the face is parallel to the registration face on the nut. If the face plate was seriously out of parallel to begin with he may have to face off the back side as well to make it balanced, but these generally run relatively slowly so they are not terribly critical.

I also found out the hard way that if you are careless installing them you will have a hard time removing them. Do not spin them on. Do not start them and then turn the lathe on to drive them home. Rotate them on by hand and give the last quarter turn a bit of a snap. It will take the same amount of effort to remove them. If you let the lathe drive them home, there will hell to pay.

If the nuts are too short/thin and let the shaft bottom out your machinist can drill a hole through them for the shaft to extend into the thickness of the plate. This also allows for vacuum attachments and other possibilities.

Any machinist should "get" the requirements in a heartbeat. Making the duplicate shaft or spud as he called it added to the cost, but he only had to make one and was then good to go for as many face plates as I wanted.

And....

Barry Irby

They do need to register either against the shoulder on the shaft of the end of the shaft or you will find there is significant "slop" in the treads and they won't run true. I chose to use the shoulder on the shaft because it was a larger surface. Maybe an Engineer can tell, but I think the shaft is in less danger of bending if you "brace" against the shoulder than if you hang the weight off the tip of the shaft.

If you can't find blind plates your machinist can cut circles out of 3/8 or 1/2" plate stock. He may also be able find or make the nuts for you.

Re: Do faceplate threads need to be fully seated?

Lyle Jamieson

David, I have a different take on this. Many times I have opposing views to many other folks. I do not like any weakness that might cause vibration or limit my creativity or design or scale because of the holding method. You see I did not use the word Chuck because that is not a good way to transfer the power and stability of the lathe to the wood. That's another issue.

Home built faceplates are not a good idea unless you have both the face and the nut machined. It is all about vibration. The threads do not hold a faceplate on. It is only when the shoulder seats that the power is transferred efficiently. I made my own faceplates when I first started turning thirty years ago. I used them for years until I realized I was turning with one hand tied behind by back with the vibration issues getting in my way. The threads and un-machined nuts caused wobble. There is space between the male and female threads and this gap is not going to be a very good way to hold anything.

I also disagree with a washer or the ring and chuck method. Every place or time you have a joint there is a weakness. Spindle to washer, washer to faceplate, faceplate to wood, each transition is a possible weak link that can lead to limitations due to vibration. Especially plastic or nylon washers are a bad idea. Do I want a soft mushy washer transferring the power to my work piece??

All these methods work, even chucks, for small scale turning. But most fail when you try to turn bigger items, or natural edges, or multi-axis, or pieces with voids, or hollow forms, or when I want to rough out a piece aggressively. I don't like to settle and be forced to diddle with small cuts because of vibration issues. The tool control we have now is easy and efficient at taking large quantities of wood in every pass. I prefer not to let vibration get in my way. And I choose not to turn with vibration, its not fun and it is not safe.

Re: Do faceplate threads need to be fully seated?

Tom Gall

IMHO- It is absolutely necessary to seat against the shoulder on the back of the spindle. I have many home-made vacuum chucks, purchased (old!!) faceplates, mini-faceplates made from flange-nuts that wouldn't bottom out on my spindle. My solution was to buy spacers (20+ yrs. ago) to fill the void. They are machined steel and very accurate. I have some to fit both 1" and 1-1/4" spindles in quite a few thicknesses. However, these days the 1/4" thick spacers seem to fill most of my needs.

These can be purchased at machine supply shops -or at- Grizzly.com ~ Use-Enco.com ~ MSCDirect.com (in order of $$$). Sorry, I don't know how to include links . Use any or all of the following words to do a "search" ……. "machine tool ~ arbor ~ spacers ~ milling machine". Prices have increased a bit since my first purchases but still can be had for about $4 and up.

Re: Do faceplate threads need to be fully seated?

john lucas

I have lots of those nuts and washer faceplates that don't seat all the way back. I don't have a problem with them. I've used them on 4 different lathes now. I would not use them for large work of course because the washer I use is only about 3/16 thick. I haven't seen any damage to the nose of my spindle or the threads. They can come loose easier if you use reverse or your lathe has electronic braking which is another good reason not to use them on larger pieces.

Do they run true. Nope. Doesn't matter. I went through a spell about 12 years ago or so where i thought faceplates had to be dead on. I trued up my faceplates using files and even some hand metal cutters in special handles. When you mount a piece of wood on there the wood still may or may not run true. I even went to the effort of cutting rebates the size of the faceplate thinking that would help. sometimes it did and sometimes it didn't. When you put a 12" piece of wood on there if the screws pull it off center just a few thousands at the back it will run out of true at the end by quite a ways. I use wasteblocks for much of the work that I put on my faceplates and the first thing you do after installing the faceplate is true up the wasteblock. As far as vibration, I don't notice any with an out of true nut and washer. You might with a larger cast iron faceplate but I sure can't detect it with my nut and washer faceplates.

I counter sink the holes on the wood side of my faceplates to try and make the wood sit flatter. When you put screws in green wood it often pulls fibers out and will make the wood not sit flat. Counter sinking the holes on the face side eliminates this problem, but the wood can still compress differently which is what pulls it off center most often.

Re: Do faceplate threads need to be fully seated?

Dave Paine

A number of nuances in the replies. The original question was about thread depth.

The minimum number of threads fully engaged is not so simple. It depends on the strength of the material the pitch of the thread and the diameter of the thread.

I did an internet search and no surprise, found a number of "answers" e.g.,

a) Minimum of 3 threads fully engaged

b) Minimum of 4 threads fully engaged

c) Minimum of 5 threads fully engaged

d) Minimum engagement depth = the diameter of the of the spindle

I think the more threads fully engaged the better, or the greater holding force.

Fewer threads mean less holding force and the potential for stripping the threads if a really bad catch.

I have a NOVA DVR XP. It looks like I have a maximum of 6 threads fully engaged.

My spindle has a shoulder which is aligned with the inner bearing race.

I normally engage the shoulder for registration of chucks.

I could engage the front of the spindle since this is machined to be 90 deg to the spindle axis.

As others said, registration is important. This is the face which causes pressure against the threads. The threads provide the strength of holding.

If the two faces e.g., nut and shoulder or flange and front of the spindle, are not parallel, then you will get runout and vibration.

A nut is normally mass produced and not designed to have a face which will run true. These need to be machined in order to run true.

Re: Do faceplate threads need to be fully seated?

John Jordan

Lyle gets an A+ for his post, take his advice.

John

Re: Do faceplate threads need to be fully seated?

Lyle Jamieson

Thanks John, I likely got that information from you years ago.