[luv2ride]

Does anyone know what the max recommended weight and size are for the 3/4 TTS collet? I do not have a PDB so can hand tighten as needed. I ask because after using the 1100 as a vertical lathe, it would be nice to mount the 5C collet chuck on swap out work pieces easier. I thought about making an adapter for the collet chuck and then started thinking that a 5" 10 lb chuck spinning at 5000 rpm held by the 3/4 collet may be pushing it.

Thoughts?

[tmarks11]

I thought about making an adapter for the collet chuck and then started thinking that a 5" 10 lb chuck spinning at 5000 rpm held by the 3/4 collet may be pushing it.

No way I would do that. If you really want to spin a chuck in the spindle, than I would get one that was R-8 mounted and remove the 3/4" collet.

[luv2ride]

I can't find an r8 that I can mount to the 5C. There are 4" chucks out there but no 5" that I am finding.

I am turning .375 rod and need a way to get it out fairly quickly or I would mount a bunch in the er collets. This is for a prototype and hopefully short production run. The tolerance isn't tight but I am looking for good surface finish with AL and brass, possibly SS and titanium too. I am actually mounting them in the 3/8" end mill holder right now and it's working decently but by no means the most rigid setup.

[SCzEngrgGroup]

Does anyone know what the max recommended weight and size are for the 3/4 TTS collet? I do not have a PDB so can hand tighten as needed. I ask because after using the 1100 as a vertical lathe, it would be nice to mount the 5C collet chuck on swap out work pieces easier. I thought about making an adapter for the collet chuck and then started thinking that a 5" 10 lb chuck spinning at 5000 rpm held by the 3/4 collet may be pushing it.

Thoughts?

The word that comes first to mind is "crazy". That would be unbelievably dangerous, for many reasons. If it ever did let go, and you happened to be standing in its path, you would not survive. Even with an R-8 shank, using something that heavy would be death-defying.

I don't see how a 5C collet would be any faster, or better in any way, than ER collets.

Regards,
Ray L.

[tmarks11]

I am turning .375 rod and need a way to get it out fairly quickly or I would mount a bunch in the er collet.

sounds like you need a manual lathe. Even a small one would do a decent job, not risk damage to your expensive Tormach spindle. Somethings are meant to be done on a lathe.

[Hirudin]

How about a 3/8" R8 collet? Skip all the accessories.

[luv2ride]

I have had a pain of a time with ER collets getting them loose on occasion. The more I think about it the better they sound though. I hope to be trying it out today.

tmarks- I need to make some compound curves and manual is not an option right now. Another machine, as much as I want one, is not an option right now. I will have access to both an ST10 and ST20 in the next year though not a lot for my personal use. I'm sure I can talk them into letting me make some parts though.

[SCzEngrgGroup]

If you're ER collets are coming loose, you're not tightening them enough. If you crank down on them properly, with two wrenches, there is no way they will ever come loose.

Regards,
Ray L.

[tmarks11]

Itmarks- I need to make some compound curves and manual is not an option right now.

Ahh, now I understand! I thought you just wanted to turn down the part to clean up the surface.

How about a 3/8" R8 collet? Skip all the accessories.

Bingo! We are so used to stacking parts using TTS, we forget where we came from. That should work great.

How much sickout of the part will you have from the collet that you need to machine?

[luv2ride]

No the other way around. I seem to get them so tight that loosening them with any frequency will develop carpel tunnel!

I figured this would be the direction of the thread but like to hear what others have done. Similar to the R8 3 jaw chucks, a 5C bolted directly to an R8 can't be much different. We put them on our lathes and run them at 3000 rpm without issues. I didn't figure using a 5C in the TTS would be effective, but like I said, it's good to hear from those who may have tried different things.

[luv2ride]

So this is an example of a few test pieces. They total 2 - 2.5" and with the small diameter I am doing them in 2 ops to minimize stickout. I turn the bullet profile with minimal stickout and then pull the rest out to make the taper on the other side. I am trying to fine tune things now so I can finish up some prototypes and gifts, possibly market a few.

[SCzEngrgGroup]

There's no way you should be having holding problems with those little parts! Is it possible there is something out of spec in either the collet chucks or collets that is preventing them from tightening fully? Perhaps the nut is bottoming on the threaded end of the chuck? With small parts like that, you should be able to break the tool, bend/break the part, or stall the spindle, before the collet lets the part slip.

Also looks like your tool is not at all sharp, or your feeds/speeds are way off - the parts should have a near mirror finish. Even at 2.5", I would expect to do the entire part in one pass, working from the bottom up, then part it off. If you really want to do two passes, use two chucks, so you can be mounting one while the other is machining, then just swap them, so the machine is never idle while you're fiddling with the chucks.

Regards,
Ray L.

[SCzEngrgGroup]

Similar to the R8 3 jaw chucks, a 5C bolted directly to an R8 can't be much different. We put them on our lathes and run them at 3000 rpm without issues. I didn't figure using a 5C in the TTS would be effective, but like I said, it's good to hear from those who may have tried different things.

The most stressful time for a heavy tool like that is when the spindle is spinning up - that's when the shank sees the highest load, and is most likely to let go if it's going to. On a lath, the chuck is usually much more securely mounted to the spindle, either using a VERY large thread, or multiple large bolts. With TTS, it is ENTIRELY up to the friction between the collet and tool shank - a MUCH weaker connection. Add to that the fact that the shank is a hollow tube, often quite thin, and you have a really marginal, and weak, mount for such a heavy tool. I've seen TTS 3-jaw chucks, and the whole idea scares the he11 out of me....

Regards,
Ray L.

[luv2ride]

There's no way you should be having holding problems with those little parts! Is it possible there is something out of spec in either the collet chucks or collets that is preventing them from tightening fully? Perhaps the nut is bottoming on the threaded end of the chuck? With small parts like that, you should be able to break the tool, bend/break the part, or stall the spindle, before the collet lets the part slip.

Not having problems holding these, just looking for a way to hold them well and remove them quickly to insert next part. I have broken a few parts off. I went out and messed around with the ER collet a little bit and I think it will work the best.

Also looks like your tool is not at all sharp, or your feeds/speeds are way off - the parts should have a near mirror finish. Even at 2.5", I would expect to do the entire part in one pass, working from the bottom up, then part it off. If you really want to do two passes, use two chucks, so you can be mounting one while the other is machining, then just swap them, so the machine is never idle while you're fiddling with the chucks.

Regards,
Ray L.

You are correct x 2. I used what I had for a tool which was an old 322 insert and didn't adjust F&S at all. Just testing the setup and now will adjust other parameters.I was getting so much vibration and chatter that the first finish suffered horribly. The right pic was a different tool and I will tweak that.

[luv2ride]

The most stressful time for a heavy tool like that is when the spindle is spinning up - that's when the shank sees the highest load, and is most likely to let go if it's going to. On a lath, the chuck is usually much more securely mounted to the spindle, either using a VERY large thread, or multiple large bolts. With TTS, it is ENTIRELY up to the friction between the collet and tool shank - a MUCH weaker connection. Add to that the fact that the shank is a hollow tube, often quite thin, and you have a really marginal, and weak, mount for such a heavy tool. I've seen TTS 3-jaw chucks, and the whole idea scares the he11 out of me....

Regards,
Ray L.

That's why I quit the idea of the TTS very quickly. An R8 mount and flange, with 3 SHCS's would be fine I think still, just like the chucks they sell. I'm quickly finding it is not worth the time or money to make one though.

[SCzEngrgGroup]

That's why I quit the idea of the TTS very quickly. An R8 mount and flange, with 3 SHCS's would be fine I think still, just like the chucks they sell. I'm quickly finding it is not worth the time or money to make one though.

I got an R8-shank 3-jaw from Shars. They seem to be out of stock most of the time, so you have to keep checking and order when it's in stock. However, I ended up mounting it on a plate, and bolt it to the table, then do most of my "turning" work by milling. That would not work as well for your parts, though, due to their shape.

Regards,
Ray L.

[Zetopan]

I can't find an r8 that I can mount to the 5C. There are 4" chucks out there but no 5" that I am finding.

Here is a 5" 3 jaw chuck with an R8 spindle. Although I must admit that I am unsure why you would want a chuck that large in the Tormach.
https://www.kmstools.com/magnum-5-3-...chuck-r8-10796

[luv2ride]

I didn't want the 3 jaw chuck, I wanted the back plate with r8 to mount my 5C collet in. The 5C is 5" diameter.

[Hirudin]

Sorry I can't help you find a 5" plate...

Your real goal is to hold a 3/8" rod, right? What do you think of the idea of simply using a 3/8" R8 collet to hold the rod in your spindle? Being without the PDB you'd have to loosen the draw bar, are you rejecting the idea because of that inconvenience? Maybe I'm just ignorant of 5C collets, but it seems like loosening a 5C collet would be comparable to loosening an R8 collet.

[luv2ride]

Sorry I can't help you find a 5" plate...

Your real goal is to hold a 3/8" rod, right? What do you think of the idea of simply using a 3/8" R8 collet to hold the rod in your spindle? Being without the PDB you'd have to loosen the draw bar, are you rejecting the idea because of that inconvenience? Maybe I'm just ignorant of 5C collets, but it seems like loosening a 5C collet would be comparable to loosening an R8 collet.

Exactly right about the R8, inconvenience of opening the door, loosening, rapping on the collet and then tightening back up. The 5C chuck is listed below from Tormach and has a square key and scroll to tighten, no messing with anything but a t wrench. It is a collet which will hold better than the set screw holder I used originally (out of convenience and to test). After trying the ER collet, I think that is the way I will go. With the ER I can also get over 5" length of stock in there for 2 parts where I may only get 2 or 3 with the R8, enough for one part causing more waste in stock.

30294 - 5C Collet Adapter for 8" Table30294 - 5C Collet Adapter for 8" Table