Turning a good tenon

hazmat · Post by **hazmat** » Wed Jun 27, 2007 1:11 pm

This is probably something I should have figured out by now.. but I really haven't. I have a hell of a time turning out tenons. I get them right(mostly) but it's a near painful process and on occassion I'll go too far and end up cutting the OD too small, having to start over. At least I can fix that with a bit of delrin so it's not a waste, just a hassle. Lately I've been setting my caliper at a nudge(that there's a technical term, fellas) larger than the final diameter and using strips of sandpaper to work it down until it fits the mortise as it should. I've been assuming this is typical.. is it? I don't mind using delrin but I really like playing with my lathe. Anybody go about this process differently? Thanks!!

pierredekat · Post by **pierredekat** » Wed Jun 27, 2007 1:24 pm

Sounds about right.

For me, I leave my blank at least 1/2 inch longer than needed. I drill an inch or so of my draft hole -- just enough to poke a live center inside, basically. Then I turn the tenon.

By doing the tenon first, if I screw it up, I can cut it off and use that extra 1/2 inch of stock and turn a new tenon. So that gives me at least two shots at getting it right.

And, yeah, I've been leaving my tenons a few thousandths oversize, and that's after sanding. Also, I wax the tenon real good with carnauba wax before inserting it into the mortise.

If I don't do that, the tenon will feel tight because it's sticky, but once it loses that stickiness, it will wind up being too lose later on. Does that make sense? The wax ensures maximum longterm snugness, IOW.

hazmat · Post by **hazmat** » Wed Jun 27, 2007 2:00 pm

I use beeswax instead of carnuba. Never thought about leavning an extra length of potential tenon on there "just in case". Good idea, though. Instead of wasting 3 inches of rod, you're only wasting 1/2 an inch. I may have to use that method in future. Thanks!!

pierredekat · Post by **pierredekat** » Wed Jun 27, 2007 4:34 pm

Yeah, I've been meaning to get me some beeswax. I just use the carnauba because I have chunks of it laying around everywhere.

ArtGuy · Post by **ArtGuy** » Thu Jun 28, 2007 10:01 am

Although bees wax certainly does work. I think carnauba is less visible on the tenon. I have used it to stops squeeks. I seems to be more durable too.

custom300 · Post by **custom300** » Thu Jun 28, 2007 10:32 pm

So is cutting the Tenon always an iterate process....cut it to approximate size, then test the fit, then sand, then test etc.

I've been using the "Kurt Delron" method up to this point. But I was going to begin trying actually cutting the tenon on my next pipe.

RadDavis · Post by **RadDavis** » Fri Jun 29, 2007 12:01 am

I cut until the end of the tenon will just fit into the mortise and then sand with 220 grit until it will go most of the way in. Then I sand with 320 until it will go all the way in, but a just little tight. Then I sand with 600 grit until I get a nice smooth fit and a smooth tenon (after buffing).

You get a feel for it after a while, and the sanding part doesn't take more than about 3-4 minutes.

Rad

hazmat · Post by **hazmat** » Fri Jun 29, 2007 7:43 am

Rad.. thanks for that. I do basically the same thing but was beginning at 150 grit on the sanding and moving up, trying to get a nice, smooth tenon. This is where I've had the majority of "oh sh*t" moments, using the 150. I'd get too close and the following grits took me past the fitting point while I worked on that shine. I figured that bit out a little and have been taking my time more, but seeing your procedure spelled out helps a ton. Are you using strips of sandpaper to work out the tenons or emory boards in various grits?

Matt

RadDavis · Post by **RadDavis** » Fri Jun 29, 2007 9:49 am

Ouch! 150 grit *would* be a little too agressive on a tenon!

I just use strips of paper.

Rad

hazmat · Post by **hazmat** » Fri Jun 29, 2007 9:57 am

Yeah.. I have several stems with too small tenons laying about my lathe table as proof! God bless delrin. They'll eventually get used for something or another.

Strips is what I've been using. I did notice on the stem I'm working on now, against the shoulder where the tenon meets the .. face, I guess... that with the strips I had left a very minute ring that didn't get sanded down well. Obviously I didn't pay close enough attention, but since I was attaching a ring to the stem it was of little consequence though it served as an object lesson for the next stem I make. I was able to chamfer the hole on the ring material to make the fit flush and it's invisible now. Thanks!

Matt

LexKY_Pipe · Post by **LexKY_Pipe** » Fri Jun 29, 2007 10:26 am

Rad

Do you use delrin tenons or do you cut most of your tenons?

RadDavis · Post by **RadDavis** » Fri Jun 29, 2007 1:33 pm

Hi Craig,

I cut all of my tenons.

Rad

LexKY_Pipe · Post by **LexKY_Pipe** » Fri Jun 29, 2007 3:04 pm

Thanks Rad. I use a similar process to yours, but I like your steps better. Gonna try that on the next batch of tenons.

Have a great weekend.

sethile · Post by **sethile** » Fri Jun 29, 2007 10:30 pm

I've been using mostly Delrin lately, and tonight I just sanded into the delrin trying to get a nice half saddle AGAIN. This time it didn't show up until I heated the stem to bend it when a noticed little pin size bubble where the very end of tenon is

Oh well, this pipe already had some other "issues" making it yet another keeper (second stummel cut with the BP bits--still learning the new process, but it sure is great!).

I've got a lot of mistakes to smoke around here

Glad I'm not trying to make a living at this yet!

So, I'm likely going back to mostly cutting tenons. In the past I've had a major problem with my live center being too thick and interfering with the cutting tool at the very tip of the tenon. I'll need to get narrower, and longer live center. Any suggestions? I've also had a tough time getting the rod too hot and deforming it. This may be from slipping in the live center, or trying to cut too much material at once, or maybe a dull cutting tool. Mostly I've just not cut tenons enough to have it down yet!

RadDavis · Post by **RadDavis** » Sat Jun 30, 2007 1:17 am

Live center?

How are you cutting your tenons, Scott?

Rad

sethile · Post by **sethile** » Sat Jun 30, 2007 11:58 pm

RadDavis wrote:Live center?

How are you cutting your tenons, Scott?

Rad

I've tried several things. Essentially I chuck up the rod stock in a mini metal lathe and rough it in for my over all stem diameter. I was then cutting the tenon, at first without using any support for it. About 2/3rds of the time that worked out fine. The other third I ended up breaking off the tenon before I'd finished turning it down. I thought maybe I was just trying to take off too much at once, and/or the cutter was dull. After experimenting some, I don't think that's the problem.

The problem may be using carbide tipped cutters. They don't seem to cut ebonite all that cleanly.

Anyway, I thought I might do better using a live center to support the end of the tenon, so I was facing off the rod with a forstner bit, and then using a live center to support it. The live center I have is too big to allow the cutting tool to get the end of the tenon cut down to the 5/16" diameter I needed (or thereabouts). It also seemed to slip sometimes, and then the tenon would be too hot and start to deform instead of cut.

So, Rad, I gather you're not using a center to support the end? What are you using for cutting tool? Maybe that's my entire problem?

RadDavis · Post by **RadDavis** » Sun Jul 01, 2007 12:30 am

So, Rad, I gather you're not using a center to support the end? What are you using for cutting tool? Maybe that's my entire problem?

No, high speed steel, and yes! I tried carbide bits in my lathe at first and then took them to a machinist to see if he could sharpen them, since they did such a crappy job. A grinding wheel won't touch them.

He asked what I was cutting, and when I told him hard rubber, he said that high speed steel would be much better, since it will get much sharper than carbide. You do need to re-sharpen it from time to time on a grinding wheel though.

Give it a try, you'll be amazed at the difference in the cut, and there's no need for any support.

Rad

sethile · Post by **sethile** » Sun Jul 01, 2007 12:41 am

GREAT, Thanks a bunch, Rad!

Man this forum is fantastic!

Frank · Post by **Frank** » Sun Jul 01, 2007 5:08 am

Well I'll be buggered! HSS. Never occurred to me that it hones sharper than carbide.

I'll have to rummage through my lathe stuff, I'm sure I have a blank HSS cutter. Just hope that I can remember the correct angles to grind it for cutting.

Post by **KurtHuhn** » Sun Jul 01, 2007 9:27 am

Those carbide cutters are really only good for hollowing forms, since they can be made so small and put on the end of a curved tool shank. For anything other than metal, I just don't think they work well. My experience is that a good high speed steel bit/chisel/whatever is going to be perfect for softer stuff like wood, vulcanite, and acrylic. I figure, if I can shave off arm hair with a freshly sharpened tool, it's going to make a good finish on my workpiece - and you can't do that with those little replaceable carbide cutters.