So this morning I've started working on the big poplar bowl.  At this point I'm not even sure if Id be able to manage cutting a mortise into this bowl.  Unfortunately I may have to go with the tenon....  Although I do not have a set of cole jaws that would fit this particular sized bowl I am at a point where I'm on a loss on figuring out what should be done.  Only because if I take it off the wood worm screw and put the face plate back on it is far too big for it to fit inside the motor housing I'm going to try it with the origional face plate that came with the lathe but I don't think it will work.  If it does I'll be able to get a mortise cut on the bottom but as of right now I may or may not be able to....  Any suggestions?

I would be very comfortable using a mortise on that size bowl. You can keep tail stock support pretty much until you're done taking out the center.

In this case seemed that the mortise worked out quite well.  I was unsure of it I had to re mount the face plate that came with the lathe.  How ever I was able to get a decent mortise cut into the bottom of the bowl.  I did cut it a hair larger than the chuck jaws would be fully closed just to give it some tightening strength when mounted on the chuck.  Either way its different working with this now I've just gotta figure out how deep I can take the hollowing with out blowing through the bottom of the bowl with the mortise.  I've already sanded only to about 400 grit including the bottom just not quite sure how I will sand the mortise just as of yet but I will probably have to pick up a 2 inch sanding disc for that.  But I did to as @lew had suggested with the mortise when cutting it.

You should be able to use your cole jaws to reverse chuck the bowl and finish off the bottom. 
Here’s a video showing how to make a bottom thickness gauge

 

I made one and is really helpful 

 

Andrew it is hard to tell from the picture but is your mortise flailed out as it goes in? My jaws flair out so I flair the mortise to match. I took a picture of one of mine. I hope it shows up good. I always get a great hold this way.

Yea I don't have to flare out the edge just as much since I have a a nova chuck.  Either way for the time being I'll be doing it the old fashioned way I've been doing it is eye balling it  I'll also be taking it off and depth checking as I go with the project.  I don't think I should have a blow through I'm leaving it a bit thicker on purpose since it is poplar wood.   Just a bit on the nerve racking side LOL.

So for what its worth the bowl is pretty much finished got it hollowed out and sanded up to 600 grit now I just need to sand the bottom up to 600 grit and put my initials on the bottom and date it stain it and it will be done...  How ever aside from the challenges this 10 inch bowl was a nice little end of weekend project to work on.  Probably will be given to my parents as an anniversary gift.

Lot of good info on this post

Yep and I think I'm going to be making one of those gauges as soon as I get a new lathe which will be nice....  Just didn't want to make one for the HF lathe because it would be a one time shot so once I get the new one it will be high time to make myself one.

“Although I do not have a set of colejaws that would fit this particular sized bowl”

 

would your cole chuck rubber stoppers fit on the inside of the bowl rim and then open the chuck to expand out gripping the bowl?

That turned out real nice Andrew!

Quite possibly but I'm not sure how well the bowl would hold on I'll have to give that a try later on today after it warms up.

1 hour ago, AndrewB said:

Quite possibly but I'm not sure how well the bowl would hold on I'll have to give that a try later on today after it warms up.

If it does work, there are a couple of things you can do to help hold the bowl for safety.

 

First, bring the tailstock up against the bottom of the bowl. If you don't want the point to pierce the bowl bottom, you can pad it with a small piece of wood, plastic, etc. You might be able to make something similar to this to cover the tailstock live center point-

 

Secondly, you can secure the bowl with nylon strapping tape-

 

Edited December 28, 20205 yr by lew

I was actually considering that how ever, I did try fitting the bowl to the inside but even on the widest of the settings on the jaws fully extended the bowl was still too big for them.  Either way not too huge of a a deal I'll just use the disc sander and sand it up to 600 my inch inch disc attatchment gets here tomorrow so I'll be able to do something about the mortise then.  Not a huge draw back.

That's too bad about the size of the cole jaws. There is always the jam chuck option, if you have some scrap wood and some padding.

 

Even though this picture shows a bowl with a tenon, it works as well with bowl mortises.

 

https://turnawoodbowl.com/jam-chuck-wooden-bowl-turning-magical-partner/

 

 

 

 

I've considered that but its okay I got the bottom sanded down and stained and finished up.  So this first one is good to go.  At some point I'll be investing in a larger set of cole jaws as well once I get a new lathe...  Hopefully that will be this month.

A few points. The Nova has dovetail jaws in expansion mode so the mortise has to match the dovetail . For appearance I like to do mine with a small area flat and then go to the rounding of the bowl as taught by Clewes. the one below is on a platter but gives you the idea. The mortise need be no larger than 1/8 at most but that flat must be of a large enough size to keep from breaking the mortise.

 

Now as to bottom treatment. Place a rubber pad over the chuck jaws and bring up the tailstock with a small piece of wood to prevent marring. to clean up outside the mortise . Then take off lathe to sand inside mortise.

    Now for alternative is use worm screw (or if you are not sure of that method use the faceplate as you do now) to start and make the mortise and sand it and then you do not have to reverse turn at all, also from Clewes method.

Edited December 28, 20205 yr by Gerald

I'll have to give that a go as well...  At some point.  I have plans for ordering a set 10 inch cole jaws if any are in stock by this weekend.  Specifically for the larger bowls.  I wasn't sure I was going to do any of the larger bowls than I had done but now that I'm getting into it its time to make the investment.    Should have done it a long time ago.  At least I'll have it when I get ready to finish off the plum wood bowl.

Another solution is to use a faceplate that is mortised in and then make a decorative insert to fit in the mortise. It’s a whole lot more stable using the faceplate and the end result is pretty decent. You can make the insert in various ways. An easy way would be to turn a cylinder that is the same size as your faceplate that is say 12” long. The. You can use the band saw to slice off a disc as you need it. You can embellish the disc by turning ridges or designs in it, do the pyrography like Gerald, or engrave it in various ways. 
Paul

I use a vacuum Chuck to finish the mortise in my bowls.